This application claims priority to U.S. provisional application No. 60/824,617, filed on Sep. 6, 2006, which is herein incorporated by reference in its entirety.
1. Field of the Invention
The invention relates to a chip package, and, more specifically, to a chip package with a specific pad between a bonding wire and an aluminum pad exposed by an opening in a passivation layer or between a bonding wire and an aluminum cap, leading the intermetallic compound (IMC) to be avoided.
2. Brief Description of the Related Art
Wirebonding is the process of providing electrical connection between a semiconductor chip and an external circuit using very fine bonding wires. The wire used in wirebonding is usually made either of gold (Au).
Referring to FIG. 1, in the prior art of a BGA (ball grid array) package, one end of a gold wire 110 is ball bonded to an aluminum cap 114 over a copper pad 120 exposed by an opening 118 a in a passivation layer 118 of a semiconductor chip 112 , and the other end of the gold wire 110 is wedge bonded to a BGA substrate 116 . The copper pad 120 of the semiconductor chip 112 can be electrically connected to a solder ball 122 under the BGA substrate 116 via the gold wire 110 and a metal trace of the BGA substrate 116 .
However, the intermetallic compound (IMC) could be formed the gold wire 110 and the aluminum cap 114 in the following high-temperature packaging process, such as in the lead-free ball planting process. The intermetallic compound has a brittle structure, leading a poor reliability for the BGA package. Besides, the gold wire 110 in a high-power application could be heated at a high temperature, which also could lead the undesired intermetallic compound (IMC) formed the gold wire 110 and the aluminum cap 114 .
It is the objective of the invention to provide a chip package for eliminating inter-metallic-compound (IMC) formation during a packaging process.
It is the objective of the invention to provide a chip package for improving the product reliability under the lead-free industrial requirement.
It is the objective of the invention to provide a chip package with a good electrical performance.
In order to reach the above objectives, the present invention provides a chip package comprising: a ball-grid-array (BGA) substrate, a glue material, such as epoxy based material or polyimide (PI), on a top surface of the BGA substrate, a semiconductor chip on the glue material, wherein the semiconductor chip comprises a passivation layer over a circuit structure, an opening in the passivation layer exposing a pad of the circuit structure, and a bonding pad over the pad exposed by the opening, a wire bonded to the bonding pad and to the BGA substrate, a polymer material, such as epoxy based material, benzocyclobutane (BCB) or polyimide, on the top surface of the BGA substrate, covering the semiconductor chip and the wire, and a lead-free solder ball on a bottom surface of the BGA substrate.
In order to reach the above objectives, the present invention provides a chip package comprising: a BGA substrate, a glue material, such as epoxy based material or polyimide (PI), on a top surface of the BGA substrate, a semiconductor chip on the glue material, wherein the semiconductor chip comprises a passivation layer over a circuit structure, an opening in the passivation layer exposing a pad of the circuit structure, and a bonding pad connected to the pad through the opening, a wire bonded to the bonding pad and to the BGA substrate, a polymer material, such as epoxy based material, benzocyclobutane (BCB) or polyimide, on the top surface of the BGA substrate, covering the semiconductor chip and the wire, and a lead-free solder ball on a bottom surface of the BGA substrate.
In order to reach the above objectives, the present invention provides a chip package comprising: a lead frame, a glue material, such as epoxy based material or polyimide (PI), on a die pad of the lead frame, a semiconductor chip on the glue material, wherein the semiconductor chip comprises a passivation layer over a circuit structure, an opening in the passivation layer exposing a pad of the circuit structure, and a bonding pad over the pad exposed by the opening, a wire bonded to the bonding pad and to a lead of the lead frame, a polymer material, such as epoxy based material, benzocyclobutane (BCB) or polyimide, enclosing the die pad, an inner partition of the lead, the semiconductor chip and the wire.
In order to reach the above objectives, the present invention provides a chip package comprising: a lead frame, a glue material, such as epoxy based material or polyimide (PI), on a die pad of the lead frame, a semiconductor chip on the glue material, wherein the semiconductor chip comprises a passivation layer over a circuit structure, an opening in the passivation layer exposing a pad of the circuit structure, and a bonding pad connected to the pad through the opening, a wire bonded to the bonding pad and to a lead of the lead frame, a polymer material, such as epoxy based material, benzocyclobutane (BCB) or polyimide, enclosing the die pad, an inner partition of the lead, the semiconductor chip and the wire.
In order to reach the above objectives, a method for fabricating a chip package comprises the following steps: providing a semiconductor chip with a bonding pad connected to a pad through an opening in a passivation layer, adhering the semiconductor chip to a top surface of a BGA substrate, bonding a wire to the bonding pad and to the BGA substrate, forming a polymer material on the top surface of the BGA substrate, covering the semiconductor chip and the wire, depositing a lead-free solder on a bottom surface of the BGA substrate, reflowing the lead-free solder at a temperature of between 200 and 300° C., and preferably between 230 and 260° C., to form a lead-free solder ball joined with the bottom surface of the BGA substrate, and cutting the polymer material and the BGA substrate.
To enable the objectives, technical contents, characteristics and accomplishments of the present invention, the embodiments of the present invention are to be described in detail in cooperation with the attached drawings below.
FIG. 1 is a cross-sectional view schematically showing a BGA package according to the prior art.
FIGS. 2A and 2B are cross-sectional views schematically showing various structures according to the present invention.
FIG. 3 is a cross-sectional view showing a semiconductor chip with a bonding pad according to the present invention.
FIGS. 4A through 4G are cross-sectional views showing a process of forming a bonding pad over a pad exposed by an opening in a passivation layer.
FIGS. 5A and 5B are cross-sectional views showing a semiconductor chip with a bonding pad on a metal cap according to the present invention.
FIGS. 6A through 6G are cross-sectional views showing a process of forming a bonding pad over a metal cap.
FIGS. 7A through 7F are cross-sectional views showing various semiconductor chips with a metal trace over a passivation layer.
FIGS. 8A through 8D are cross-sectional views showing various semiconductor chips with a metal trace over a polymer layer.
FIGS. 9A through 9E are sectional views showing a process according to one embodiment of the present invention.
FIGS. 10A through 10L are sectional views showing various chip packages according to the present invention.
FIGS. 11A through 11D are sectional views showing a process according to another one embodiment of the present invention.
FIGS. 12A through 12L are sectional views showing various chip packages according to the present invention.
Referring to FIG. 2A, a semiconductor substrate or semiconductor blank wafer 2 may be a silicon substrate or silicon wafer, a GaAs substrate or GaAs wafer, or a SiGe substrate or SiGe wafer. Multiple semiconductor devices 4 are formed in or over the semiconductor substrate 2 . The semiconductor device 4 may be a memory device, a logic device, a passive device, such as resistor, capacitor, inductor or filter, or an active device, such as p-channel MOS device, n-channel MOS device, CMOS (Complementary Metal Oxide Semiconductor), BJT (Bipolar Junction Transistor) or BiCMOS (Bipolar CMOS) device.
A circuit structure 6 , fine line metal trace structure, is formed over the semiconductor substrate 2 and connect to the semiconductor device 4 . The circuit structure 6 comprises multiple patterned metal layers 8 having a thickness t1 of less than 3 micrometers (such as between 0.2 and 2 μm) and multiple metal plugs 10 . For example, the patterned metal layers 8 and the metal plugs 10 are principally made of copper, wherein the patterned metal layer 8 is a copper layer having a thickness of less than 3 μm (such as between 0.2 and 2 μm). Alternatively, the patterned metal layer 8 is principally made of aluminum or aluminum-alloy, and the metal plug 10 is principally made of tungsten, wherein the patterned metal layer 8 is an aluminum-containing layer having a thickness of less than 3 μm (such as between 0.2 and 2 μm).
One of the patterned metal layers 8 may be formed by a damascene process including sputtering an adhesion/barrier layer, such as tantalum or tantalum nitride, on an insulating layer, composed of Low-K oxide and oxynitride, and in an opening in the insulating layer, then sputtering a first copper layer on the adhesion/barrier layer, then electroplating a second copper layer on the first copper layer, then removing the first and second copper layers and the adhesion/barrier layer outside the opening in the insulating layer using a chemical mechanical polishing (CMP) process. Alternatively, one of the patterned metal layer 8 may be formed by a process including sputtering an aluminum-alloy layer, containing more than 90 wt % aluminum and less than 10 wt % copper, on an insulating layer, such as oxide, then patterning the aluminum-alloy layer using photolithography and etching processes.
Multiple dielectric layers 12 having a thickness t2 of less than 3 micrometers, such as between 0.3 and 2.5 μm, are located over the semiconductor substrate 2 and interposed respectively between the neighboring patterned metal layers 8 , and the neighboring patterned metal layers 8 are interconnected through the metal plugs 10 inside the dielectric layer 12 . The dielectric layer 12 is commonly formed by a chemical vapor deposition (CVD) process. The material of the dielectric layer 12 may include silicon oxide, silicon oxynitride, TEOS (Tetraethoxysilane), a compound containing silicon, carbon, oxygen and hydrogen (such as Si w C x O y H z ), silicon nitride (such as Si 3 N 4 ), FSG (Fluorinated Silicate Glass), Black Diamond, SiLK, a porous silicon oxide, a porous compound containing nitrogen, oxygen and silicon, SOG (Spin-On Glass), BPSG (borophosphosilicate glass), a polyarylene ether, PBO (Polybenzoxazole), or a material having a low dielectric constant (K) of between 1.5 and 3, for example.
A passivation layer 14 is formed over the circuit structure 6 and over the dielectric layers 12 . The passivation layer 14 can protect the semiconductor devices 4 and the circuit structure 6 from being damaged by moisture and foreign ion contamination. In other words, mobile ions (such as sodium ion), transition metals (such as gold, silver and copper) and impurities can be prevented from penetrating through the passivation layer 14 to the semiconductor devices 4 , such as transistors, polysilicon resistor elements and polysilicon-polysilicon capacitor elements, and to the circuit structure 6 .
The passivation layer 14 is commonly made of silicon oxide (such as SiO 2 ), silicon oxynitride, silicon nitride (such as Si 3 N 4 ), or PSG (phosphosilicate glass). The passivation layer 14 commonly has a thickness t3 of more than 0.3 μm, such as between 0.3 and 1.5 μm. In a preferred case, the silicon nitride layer in the passivation layer 14 has a thickness of more than 0.3 μm. Ten methods for depositing the passivation layer 14 are described as below.
In a first method, the passivation layer 14 is formed by depositing a silicon oxide layer with a thickness of between 0.2 and 1.2 μm using a CVD method and then depositing a silicon nitride layer with a thickness of 0.2 and 1.2 μm on the silicon oxide layer using a CVD method.
In a second method, the passivation layer 14 is formed by depositing a silicon oxide layer with a thickness of between 0.2 and 1.2 μm using a CVD method, next depositing a silicon oxynitride layer with a thickness of between 0.05 and 0.15 μm on the silicon oxide layer using a Plasma Enhanced CVD (PECVD) method, and then depositing a silicon nitride layer with a thickness of between 0.2 and 1.2 μm on the silicon oxynitride layer using a CVD method.
In a third method, the passivation layer 14 is formed by depositing a silicon oxynitride layer with a thickness of between 0.05 and 0.15 μm using a CVD method, next depositing a silicon oxide layer with a thickness of between 0.2 and 1.2 μm on the silicon oxynitride layer using a CVD method, and then depositing a silicon nitride layer with a thickness of between 0.2 and 1.2 μm on the silicon oxide layer using a CVD method.
In a fourth method, the passivation layer 14 is formed by depositing a first silicon oxide layer with a thickness of between 0.2 and 0.5 μm using a CVD method, next depositing a second silicon oxide layer with a thickness of between 0.5 and 1 μm on the first silicon oxide layer using a spin-coating method, next depositing a third silicon oxide layer with a thickness of between 0.2 and 0.5 μm on the second silicon oxide layer using a CVD method, and then depositing a silicon nitride layer with a thickness of 0.2 and 1.2 μm on the third silicon oxide using a CVD method.
In a fifth method, the passivation layer 14 is formed by depositing a silicon oxide layer with a thickness of between 0.5 and 2 μm using a High Density Plasma CVD (HDP-CVD) method and then depositing a silicon nitride layer with a thickness of 0.2 and 1.2 μm on the silicon oxide layer using a CVD method.
In a sixth method, the passivation layer 14 is formed by depositing an Undoped Silicate Glass (USG) layer with a thickness of between 0.2 and 3 μm, next depositing an insulating layer of TEOS, PSG or BPSG (borophosphosilicate glass) with a thickness of between 0.5 and 3 μm on the USG layer, and then depositing a silicon nitride layer with a thickness of 0.2 and 1.2 μm on the insulating layer using a CVD method.
In a seventh method, the passivation layer 14 is formed by optionally depositing a first silicon oxynitride layer with a thickness of between 0.05 and 0.15 μm using a CVD method, next depositing a silicon oxide layer with a thickness of between 0.2 and 1.2 μm on the first silicon oxynitride layer using a CVD method, next optionally depositing a second silicon oxynitride layer with a thickness of between 0.05 and 0.15 μm on the silicon oxide layer using a CVD method, next depositing a silicon nitride layer with a thickness of between 0.2 and 1.2 μm on the second silicon oxynitride layer or on the silicon oxide using a CVD method, next optionally depositing a third silicon oxynitride layer with a thickness of between 0.05 and 0.15 μm on the silicon nitride layer using a CVD method, and then depositing a silicon oxide layer with a thickness of between 0.2 and 1.2 μm on the third silicon oxynitride layer or on the silicon nitride layer using a CVD method.
In a eighth method, the passivation layer 14 is formed by depositing a first silicon oxide layer with a thickness of between 0.2 and 1.2 μm using a CVD method, next depositing a second silicon oxide layer with a thickness of between 0.5 and him on the first silicon oxide layer using a spin-coating method, next depositing a third silicon oxide layer with a thickness of between 0.2 and 1.2 μm on the second silicon oxide layer using a CVD method, next depositing a silicon nitride layer with a thickness of between 0.2 and 1.2 μm on the third silicon oxide layer using a CVD method, and then depositing a fourth silicon oxide layer with a thickness of between 0.2 and 1.2 μm on the silicon nitride layer using a CVD method.
In a ninth method, the passivation layer 14 is formed by depositing a first silicon oxide layer with a thickness of between 0.5 and 2 μm using a HDP-CVD method, next depositing a silicon nitride layer with a thickness of between 0.2 and 1.2 μm on the first silicon oxide layer using a CVD method, and then depositing a second silicon oxide layer with a thickness of between 0.5 and 2 μm on the silicon nitride using a HDP-CVD method.
In a tenth method, the passivation layer 14 is formed by depositing a first silicon nitride layer with a thickness of between 0.2 and 1.2 μm using a CVD method, next depositing a silicon oxide layer with a thickness of between 0.2 and 1.2 μm on the first silicon nitride layer using a CVD method, and then depositing a second silicon nitride layer with a thickness of between 0.2 and 1.2 μm on the silicon oxide layer using a CVD method.
An opening 14 a in the passivation layer 14 exposes a pad 16 of the circuit structure 6 used to input or output signals or to be connected to a power source or a ground reference. The pad 16 may have a thickness t4 of between 0.4 and 3 μm or between 0.2 and 2 μm. For example, the pad 16 may be composed of a sputtered aluminum layer or a sputtered aluminum-copper-alloy layer with a thickness of between 0.2 and 2 μm. Alternatively, the pad 16 may include an electroplated copper layer with a thickness of between 0.2 and 2 μm, and a barrier layer, such as tantalum or tantalum nitride, on a bottom surface and side walls of the electroplated copper layer.
Therefore, the pad 16 can be an aluminum pad, principally made of sputtered aluminum with a thickness of between 0.2 and 2 μm. Alternatively, the pad 16 can be a copper pad, principally made of electroplated copper with a thickness of between 0.2 and 2 μm.
The opening 14 a may have a transverse dimension d, from a top view, of between 0.5 and 20 μm or between 20 and 200 μm. The shape of the opening 14 a from a top view may be a circle, and the diameter of the circle-shaped opening 14 a may be between 0.5 and 20 μm or between 20 and 200 μm. Alternatively, the shape of the opening 14 a from a top view may be a square, and the width of the square-shaped opening 14 a may be between 0.5 and 20 μm or between 20 and 200 μm. Alternatively, the shape of the opening 14 a from a top view may be a polygon, such as hexagon or octagon, and the polygon-shaped opening 14 a may have a width of between 0.5 and 20 μm or between 20 and 200 μm. Alternatively, the shape of the opening 14 a from a top view may be a rectangle, and the rectangle-shaped opening 14 a may have a shorter width of between 0.5 and 20 μm or between 20 and 200 μm. Further, there may be some of the semiconductor devices 4 under the pad 16 exposed by the opening 14 a . Alternatively, there may be no active devices under the pad 16 exposed by the opening 14 a.
Referring to FIG. 2B, a metal cap 18 having a thickness of between 0.4 and 3 μm can be optionally formed on the pad 16 exposed by the opening 14 a in the passivation layer 14 to prevent the pad 16 from being oxidized or contaminated. For example, the metal cap 18 may comprise a barrier layer having a thickness of between 0.01 and 0.7 μm on the pad 16 , such as copper pad, exposed by the opening 14 a , and an aluminum-containing layer having a thickness of between 0.4 and 2 μm on the barrier layer, wherein the barrier layer may be made of titanium, a titanium-tungsten alloy, titanium nitride, tantalum, tantalum nitride, chromium or alloy of refractory metal, and the aluminum-containing layer may be an aluminum layer, an aluminum-copper alloy layer or an Al—Si—Cu alloy layer. Alternatively, the metal cap 18 may be an aluminum-containing layer having a thickness of between 0.4 and 2 μm directly on the pad 16 , such as copper pad, exposed by the opening 14 a , without the above-mentioned barrier layer between the aluminum-containing layer and the pad 16 , wherein the aluminum-containing layer may be an aluminum layer, an aluminum-copper alloy layer or an Al—Si—Cu alloy layer.
For example, the metal cap 18 may include a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm on the pad 16 , principally made of electroplated copper, exposed by the opening 14 a , and an aluminum-containing layer, such as aluminum layer or aluminum-alloy layer, having a thickness of between 0.4 and 2 μm on the tantalum-containing layer. Alternatively, the metal cap 18 may include a titanium-containing layer, such as titanium layer or titanium-tungsten-alloy layer, having a thickness of between 0.01 and 0.7 μm on the pad 16 , principally made of electroplated copper, exposed by the opening 14 a , and an aluminum-containing layer, such as aluminum layer or aluminum-alloy layer, having a thickness of between 0.4 and 2 μm on the tantalum-containing layer.
The semiconductor substrate 2 , the circuit structure 6 , the dielectric layer 12 , the passivation layer 14 and the pad 16 are described in the above paragraphs. Below, the scheme 20 between the semiconductor substrate 2 and the passivation layer 14 may be any one of the structures shown in FIGS. 2A and 2B between the semiconductor substrate 2 and the passivation layer 14 ; the scheme 20 represents the combination of the semiconductor devices 4 , the circuit structure 6 (including the metal layers 8 and the metal plugs 10 ) and the dielectric layers 12 in FIG. 2A and FIG. 2B.
Referring to FIG. 3, in the present invention, a bonding pad 22 having a thickness of between 1 and 20 μm, and preferably of between 3 and 5 μm, can be formed on the pad 16 , such as aluminum pad or copper pad, exposed by the opening 14 a in the passivation layer 14 . The bonding pad 22 may be used to be bonded with a wire, such as gold wire. A method of forming the bonding pad 22 on the pad 16 exposed by the opening 14 a can be referred to FIGS. 4A-4G After a semiconductor wafer is formed with the bonding pad 22 , the semiconductor wafer can be separated into multiple individual semiconductor chips 23 , integrated circuit chips, by a laser cutting process or by a mechanical cutting process.
Referring to FIG. 4A, an adhesion/barrier layer 24 having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, can be sputtered on the passivation layer 14 and on the pad 16 , such as aluminum pad or copper pad, exposed by the opening 14 a . The material of the adhesion/barrier layer 24 may include titanium, a titanium-tungsten alloy, titanium nitride, chromium, tantalum, tantalum nitride, an alloy of refractory metal, or a composite of the abovementioned materials. Alternatively, the adhesion/barrier layer 24 can be formed by an evaporation process.
For example, the adhesion/barrier layer 24 may be formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of aluminum, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of aluminum, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of aluminum, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of aluminum, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of aluminum, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of aluminum, exposed by the opening 14 a.
For example, the adhesion/barrier layer 24 may be formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of copper, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of copper, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of copper, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of copper, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of copper, exposed by the opening 14 a . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the pad 16 , principally made of copper, exposed by the opening 14 a.
Referring to FIG. 4B, a seed layer 26 having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, can be sputtered on the adhesion/barrier layer 24 . Alternatively, the seed layer 26 can be formed by a vapor deposition method, an electroless plating method or a PVD (Physical Vapor Deposition) method. The seed layer 26 is beneficial to electroplating a metal layer thereon. Thus, the material of the seed layer 26 varies with the material of the electroplated metal layer formed on the seed layer 26 . When a gold layer is to be electroplated on the seed layer 26 , gold is a preferable material to the seed layer 26 . When a copper layer is to be electroplated on the seed layer 26 , copper is a preferable material to the seed layer 26 . When a palladium layer is to be electroplated on the seed layer 26 , palladium is a preferable material to the seed layer 26 .
For example, when the adhesion/barrier layer 24 is formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-tungsten-alloy layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum layer.
For example, when the adhesion/barrier layer 24 is formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-tungsten-alloy layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum layer.
For example, when the adhesion/barrier layer 24 is formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-tungsten-alloy layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum layer.
Referring to FIG. 4C, a photoresist layer 28 , such as positive-type photoresist layer, having a thickness of between 1 and 25 μm, and preferably of between 3 and 10 μm, is spin-on coated on the seed layer 26 . Referring to FIG. 4D, the photoresist layer 28 is patterned with the processes of exposure, development, etc., to form an opening 28 a in the photoresist layer 28 exposing the seed layer 26 over the pad 16 . A 1× stepper or 1× contact aligner can be used to expose the photoresist layer 28 during the process of exposure.
For example, the photoresist layer 28 can be formed by spin-on coating a positive-type photosensitive polymer layer having a thickness of between 1 and 25 μm, and preferably of between 3 and 10 μm, on the seed layer 26 , then exposing the photosensitive polymer layer using a 1× stepper or 1× contact aligner with at least two of G-line having a wavelength ranging from 434 to 438 nm, H-line having a wavelength ranging from 403 to 407 nm, and I-line having a wavelength ranging from 363 to 367 nm, illuminating the photosensitive polymer layer, that is, G-line and H-line, G-line and I-line, H-line and I-line, or G-line, H-line and I-line illuminate the photosensitive polymer layer, then developing the exposed polymer layer, and then removing the residual polymeric material or other contaminants form the seed layer 26 with an O 2 plasma or a plasma containing fluorine of below 200 PPM and oxygen, such that the photoresist layer 28 can be patterned with an opening 28 a in the photoresist layer 28 exposing the seed layer 26 over the pad 16 .
Referring to FIG. 4E, a metal layer 30 having a thickness of between 1 and 20 μm, and preferably of between 3 and 5 μm, can be electroplated and/or electroless plated over the seed layer 26 exposed by the opening 28 a . The material of the metal layer 30 may include gold, copper, nickel or palladium.
For example, the metal layer 30 may be formed by electroplating a gold layer with a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the seed layer 26 , made of gold, exposed by the opening 28 a . Alternatively, the metal layer 30 may be formed by electroplating a palladium layer with a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the seed layer 26 , made of palladium, exposed by the opening 28 a . Alternatively, the metal layer 30 may be formed by electroplating a copper layer with a thickness of between 1 and 10 μm on the seed layer 26 , made of copper, exposed by the opening 28 a , then electroplating a nickel layer with a thickness of between 1 and 5 μm on the copper layer in the opening 28 a , and then electroplating a gold layer with a thickness of between 1 and 5 μm on the nickel layer in the opening 28 a , wherein the thickness of the copper layer, the nickel layer and the gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the metal layer 30 may be formed by electroplating a copper layer with a thickness of between 1 and 13 μm on the seed layer 26 , made of copper, exposed by the opening 28 a , then electroplating a nickel layer with a thickness of between 1 and 5 μm on the copper layer in the opening 28 a , and then electroless plating a gold layer with a thickness of between 0.05 and 2 μm on the nickel layer in the opening 28 a , wherein the thickness of the copper layer, the nickel layer and the gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the metal layer 30 may be formed by electroplating a copper layer with a thickness of between 1 and 10 μm on the seed layer 26 , made of copper, exposed by the opening 28 a , then electroplating a nickel layer with a thickness of between 1 and 5 μm on the copper layer in the opening 28 a , and then electroplating a palladium layer with a thickness of between 1 and 5 μm on the nickel layer in the opening 28 a , wherein the thickness of the copper layer, the nickel layer and the palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the metal layer 30 may be formed by electroplating a copper layer with a thickness of between 1 and 13 μm on the seed layer 26 , made of copper, exposed by the opening 28 a , then electroplating a nickel layer with a thickness of between 1 and 5 μm on the copper layer in the opening 28 a , and then electroless plating a palladium layer with a thickness of between 0.05 and 2 μm on the nickel layer in the opening 28 a , wherein the thickness of the copper layer, the nickel layer and the palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
Referring to FIG. 4F, after the metal layer 30 is formed, most of the photoresist layer 28 can be removed using an organic solution with amide. However, some residuals from the photoresist layer 28 could remain on the metal layer 30 and on the seed layer 26 . Thereafter, the residuals can be removed from the metal layer 30 and from the seed layer 26 with a plasma, such as O 2 plasma or plasma containing fluorine of below 200 PPM and oxygen.
Referring to FIG. 4G, the seed layer 26 and the adhesion/barrier layer 24 not under the metal layer 30 are subsequently removed with a dry etching method or a wet etching method. As to the wet etching method, when the seed layer 26 is a gold layer, it can be etched with an iodine-containing solution, such as solution containing potassium iodide; when the seed layer 26 is a copper layer, it can be etched with a solution containing NH 4 OH; when the adhesion/barrier layer 24 is a titanium-tungsten-alloy layer, it can be etched with a solution containing hydrogen peroxide; when the adhesion/barrier layer 24 is a titanium layer, it can be etched with a solution containing hydrogen fluoride; when the adhesion/barrier layer 24 is a chromium layer, it can be etched with a solution containing potassium ferricyanide. As to the dry etching method, when the seed layer 26 is a gold layer, it can be removed with an ion milling process or with an Ar sputtering etching process; when the adhesion/barrier layer 24 is a titanium layer or a titanium-tungsten-alloy layer, it can be etched with a chlorine-containing plasma etching process or with an RIE process. Generally, the dry etching method to etch the seed layer 26 and the adhesion/barrier layer 24 not under the metal layer 30 may include a chemical plasma etching process, a sputtering etching process, such as argon sputter process, or a chemical vapor etching process.
Thereby, in the present invention, the bonding pad 22 can be formed on the pad 16 exposed by the opening 14 a . The bonding pad 22 can be formed of the adhesion/barrier layer 24 , the seed layer 26 on the adhesion/barrier layer 24 and the electroplated metal layer 30 on the seed layer 26 . The material of bonding pad 22 may comprise titanium, titanium-tungsten alloy, titanium nitride, chromium, tantalum nitride, tantalum, gold, copper, palladium or nickel. Based on the above teaching, the bonding pad 22 may include the following fashions.
For example, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
For example, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
For example, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of copper, typically called a copper pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
For example, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
For example, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
For example, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the pad 16 , principally made of aluminum, typically called an aluminum pad, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
After a semiconductor wafer is formed with the bonding pad 22 , the semiconductor wafer can be diced into a plurality of individual semiconductor chips 23 , IC (integrated circuit) chips, as shown in FIG. 3.
Referring to FIGS. 5A and 5B, in the present invention, a bonding pad 22 having a thickness of between 1 and 20 μm, and preferably of between 3 and 5 μm, can be formed on the metal cap 18 . The metal cap 18 may comprise a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm on the pad 16 , such as copper pad, exposed by the opening 14 a , and an aluminum-containing layer, such as aluminum layer, aluminum-copper-alloy layer or Al—Si—Cu alloy layer, having a thickness of between 0.4 and 2 μm on the tantalum-containing layer. The bonding pad 22 may be used to be bonded with a wire, such as gold wire. The bonding pad 22 may be formed on the entire upper surface of the metal cap 18 and on the upper surface of the passivation layer 14 near the metal cap 18 , as shown in FIG. 5A. Alternatively, the bonding pad 22 may be formed on a portion of a top surface of the metal cap 18 , as shown in FIG. 5B. A method of forming the bonding pad 22 on the metal cap 18 can be referred to FIGS. 6A-6G. FIGS. 6A-6G illustrate a process for forming the bonding pad 22 shown in FIG. 5A on the metal cap 18 . Alternatively, the illustrations of FIGS. 6A-6G can be applied to a process for forming the bonding pad 22 shown in FIG. 5B on the metal cap 18 . After a semiconductor wafer is formed with the bonding pad 22 , the semiconductor wafer can be separated into multiple individual semiconductor chips 31 , integrated circuit chips, by a laser cutting process or by a mechanical cutting process.
Referring to FIG. 6A, an adhesion/barrier layer 24 having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, can be sputtered on the passivation layer 14 and on the metal cap 18 , wherein the metal cap 18 may comprise a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm on the pad 16 , such as copper pad, exposed by the opening 14 a , and an aluminum-containing layer, such as aluminum layer, aluminum-copper-alloy layer or Al—Si—Cu alloy layer, having a thickness of between 0.4 and 2 μm on the tantalum-containing layer. The material of the adhesion/barrier layer 24 may include titanium, a titanium-tungsten alloy, titanium nitride, chromium, tantalum, tantalum nitride, an alloy of refractory metal, or a composite of the abovementioned materials. Alternatively, the adhesion/barrier layer 24 can be formed by an evaporation process.
For example, the adhesion/barrier layer 24 may be formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the aluminum-containing layer of the metal cap 18 . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the aluminum-containing layer of the metal cap 18 . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the aluminum-containing layer of the metal cap 18 . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the aluminum-containing layer of the metal cap 18 . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the aluminum-containing layer of the metal cap 18 . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the aluminum-containing layer of the metal cap 18 . Alternatively, the adhesion/barrier layer 24 may be formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the passivation layer 14 and on the aluminum-containing layer of the metal cap 18 .
Referring to FIG. 6B, a seed layer 26 having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, can be sputtered on the adhesion/barrier layer 24 . Alternatively, the seed layer 26 can be formed by a vapor deposition method, an electroless plating method or a PVD (Physical Vapor Deposition) method. The seed layer 26 is beneficial to electroplating a metal layer thereon. Thus, the material of the seed layer 26 varies with the material of the electroplated metal layer formed on the seed layer 26 . When a gold layer is to be electroplated on the seed layer 26 , gold is a preferable material to the seed layer 26 . When a copper layer is to be electroplated on the seed layer 26 , copper is a preferable material to the seed layer 26 . When a palladium layer is to be electroplated on the seed layer 26 , palladium is a preferable material to the seed layer 26 .
For example, when the adhesion/barrier layer 24 is formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-tungsten-alloy layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a gold layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum layer.
For example, when the adhesion/barrier layer 24 is formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-tungsten-alloy layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a copper layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum layer.
For example, when the adhesion/barrier layer 24 is formed by sputtering a titanium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-tungsten-alloy layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-tungsten-alloy layer. When the adhesion/barrier layer 24 is formed by sputtering a titanium-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a chromium layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum-nitride layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-nitride layer. When the adhesion/barrier layer 24 is formed by sputtering a tantalum layer with a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, the seed layer 26 can be formed by sputtering a palladium layer with a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum layer.
Referring to FIG. 6C, a photoresist layer 28 , such as positive-type photoresist layer, having a thickness of between 1 and 25 μm, and preferably of between 3 and 10 μm, is spin-on coated on the seed layer 26 . Referring to FIG. 6D, the photoresist layer 28 is patterned with the processes of exposure, development, etc., to form an opening 28 a in the photoresist layer 28 exposing the seed layer 26 over the pad 16 . A 1× stepper or 1× contact aligner can be used to expose the photoresist layer 28 during the process of exposure.
For example, the photoresist layer 28 can be formed by spin-on coating a positive-type photosensitive polymer layer having a thickness of between 1 and 25 μm, and preferably of between 3 and 10 μm, on the seed layer 26 , then exposing the photosensitive polymer layer using a 1× stepper or 1× contact aligner with at least two of G-line having a wavelength ranging from 434 to 438 nm, H-line having a wavelength ranging from 403 to 407 nm, and I-line having a wavelength ranging from 363 to 367 nm, illuminating the photosensitive polymer layer, that is, G-line and H-line, G-line and I-line, H-line and I-line, or G-line, H-line and I-line illuminate the photosensitive polymer layer, then developing the exposed polymer layer, and then removing the residual polymeric material or other contaminants form the seed layer 26 with an O 2 plasma or a plasma containing fluorine of below 200 PPM and oxygen, such that the photoresist layer 28 can be patterned with an opening 28 a in the photoresist layer 28 exposing the seed layer 26 over the pad 16 .
Referring to FIG. 6E, a metal layer 30 having a thickness of between 1 and 20 μm, and preferably of between 3 and 5 μm, can be electroplated and/or electroless plated over the seed layer 26 exposed by the opening 28 a . The material of the metal layer 30 may include gold, copper, nickel or palladium. The specification of the metal layer 30 shown in FIG. 6E can be referred to as the metal layer 30 illustrated in FIG. 4E. The process of forming the metal layer 30 shown in FIG. 6E can be referred to as the process of forming the metal layer 30 illustrated in FIG. 4E.
Referring to FIG. 6F, after the metal layer 30 is formed, most of the photoresist layer 28 can be removed using an organic solution with amide. However, some residuals from the photoresist layer 28 could remain on the metal layer 30 and on the seed layer 26 . Thereafter, the residuals can be removed from the metal layer 30 and from the seed layer 26 with a plasma, such as O 2 plasma or plasma containing fluorine of below 200 PPM and oxygen.
Referring to FIG. 6G, the seed layer 26 and the adhesion/barrier layer 24 not under the metal layer 30 are subsequently removed with a dry etching method or a wet etching method. The process of removing the seed layer 26 and the adhesion/barrier layer 24 not under the metal layer 30 , as shown in FIG. 6G, can be referred to as the process of removing the seed layer 26 and the adhesion/barrier layer 24 not under the metal layer 30 , as illustrated in FIG. 4G.
Thereby, in the present invention, the bonding pad 22 can be formed on the aluminum-containing layer of the metal cap 18 . The bonding pad 22 can be formed of the adhesion/barrier layer 24 , the seed layer 26 on the adhesion/barrier layer 24 and the electroplated metal layer 30 on the seed layer 26 . The material of bonding pad 22 may comprise titanium, titanium-tungsten alloy, titanium nitride, chromium, tantalum nitride, tantalum, gold, copper, palladium or nickel. Based on the above teaching, the bonding pad 22 may include the following fashions.
For example, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a titanium-containing layer, such as titanium layer, titanium-tungsten-alloy layer or titanium-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the titanium-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
For example, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a chromium layer having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the chromium layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm.
For example, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of gold, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, and an electroplated gold layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of palladium, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, and an electroplated palladium layer having a thickness of between 1 and 20 μm, such as between 3 and 5 μm or between 1 and 4 μm, on the sputtered seed layer. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated gold layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated gold layer having a thickness of between 0.05 and 2 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroless plated gold layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 10 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroplated palladium layer having a thickness of between 1 and 5 μm on the electroplated nickel layer, wherein the thickness of the electroplated copper layer, the electroplated nickel layer and the electroplated palladium layer is between 1 and 20 μm, and preferably of between 3 and 5 μm. Alternatively, the bonding pad 22 may be formed of a tantalum-containing layer, such as tantalum layer or tantalum-nitride layer, having a thickness of between 0.01 and 0.7 μm, and preferably of between 0.03 and 0.7 μm, on the aluminum-containing layer of the metal cap 18 on the pad 16 , principally made of copper, exposed by the opening 14 a , a sputtered seed layer, made of copper, having a thickness of between 0.03 and 1 μm, and preferably of between 0.03 and 0.7 μm, on the tantalum-containing layer, an electroplated copper layer having a thickness of between 1 and 13 μm on the sputtered seed layer, an electroplated nickel layer having a thickness of between 1 and 5 μm on the electroplated copper layer, and an electroless plated palladium layer having a thickness of between 0.05 and 2 μm on the electroplated