Title:
Apparatus for plating treatment
Kind Code:
A1


Abstract:
A plating processing device is so arranged that at least a part of a portion touching plating liquid is made of a material whose change rate of surface roughness in response to a removing agent is lower than resin when the material and the resin are measured in the same conditions. For example, a storage tank (1), a plating processing tank (2), a buffer tank (3), and a pipe (9) are made of hard glass and quartz glass. With this, it is possible to prevent a plating material from being deposited as foreign body on wall surfaces of the plating processing tank, etc.



Inventors:
Kawakami, Katsuji (Fukuyama-shi, Hiroshima, JP)
Sawai, Keiichi (Fukuyama-shi, Hiroshima, JP)
Oda, Hajime (Okayama-shi, Okayama, JP)
Application Number:
10/484628
Publication Date:
10/21/2004
Filing Date:
01/23/2004
Assignee:
KAWAKAMI KATSUJI
SAWAI KEIICHI
ODA HAJIME
Primary Class:
Other Classes:
257/E21.508, 257/E21.175
International Classes:
C25D17/00; C25D17/02; C25D21/02; C25D21/12; H01L21/288; H01L21/60; H01L23/50; (IPC1-7): C25B15/08
View Patent Images:



Primary Examiner:
SMITH, NICHOLAS A
Attorney, Agent or Firm:
NIXON & VANDERHYE, PC (901 NORTH GLEBE ROAD, 11TH FLOOR, ARLINGTON, VA, 22203, US)
Claims:
1. A plating processing device which plates a plating target object by supplying plating liquid containing a plating material and causing said plating target object to touch said plating liquid, and, if the plating material is deposited on an undesired position, removes the plating material from the undesired position using a removing agent, wherein: at least a part of a portion touching said plating liquid is made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when said material and the resin are measured in same conditions.

2. The plating processing device as set forth in claim 1, comprising: a plating processing tank for causing said plating target object to touch said plating liquid, wall surfaces of said plating processing tank being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when said material and the resin are measured in same conditions.

3. The plating processing device as set forth in claim 1, comprising: a plating processing tank for causing said plating target object to touch said plating liquid; and a plating processing tank pipe for conveying said plating liquid to said plating processing tank, wall surfaces of said plating processing tank pipe being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when said material and the resin are measured in same conditions.

4. The plating processing device as set forth in claim 1, comprising: a plating processing tank for causing said plating target object to touch said plating liquid; and a storage tank for storing said plating liquid which is to be supplied to said plating processing tank, wall surfaces of said storage tank being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when said material and the resin are measured in same conditions.

5. The plating processing device as set forth in claim 4, further comprising: a heating tank for containing said storage tank so as to heat said plating liquid in said storage tank using heat conduction.

6. The plating processing device as set forth in claim 1, further comprising: a plating processing tank for causing said plating target object to touch said plating liquid; a plating processing tank pipe for conveying said plating liquid to said plating processing tank; and an ultrasonic flowmeter provided at a portion of said plating processing tank pipe, wall surfaces of said portion of said plating processing tank pipe being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when said material and the resin are measured in same conditions.

7. The plating processing device as set forth in claim 1, wherein: said material whose change rate of surface roughness in response to the removing agent is lower than resin when said material and the resin are measured in same conditions is glass.

8. The plating processing device as set forth in claim 7, wherein: said glass is hard glass.

9. The plating processing device as set forth in claim 7, wherein: said glass is quartz glass.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a plating processing device used in, for example, a device for manufacturing semiconductor integrated circuits, etc.

BACKGROUND ART

[0002] Electronic devices such as portable digital assistants have become smaller in size and lighter in weight. In response to this, compactness, lightness in weight, and high packaging density have been required for semiconductor integrated circuits mounted on these electronic devices.

[0003] A commonly used method to achieve the compactness and high packaging density of semiconductor integrated circuits, etc. (hereinafter referred to as semiconductor devices) is to use a so-called bump electrode. With this method, plating technique is applied to form a bump electrode of gold (Au) on a predetermined position on a surface of the semiconductor device, and the bump electrode is used to directly package the semiconductor device on a packaging substrate.

[0004] FIG. 3 shows an outline of a conventional plating processing device.

[0005] FIG. 3 shows a storage tank 51, a plating processing tank 52, a buffer tank 53, a circulating pump 54, a float-type flowmeter 55, filters 56, a heat exchanging unit 57, and pipes 58. The storage tank 51, the plating processing tank 52, the buffer tank 53, the heat exchanging unit 57, and the pipes 58 are made of resin material.

[0006] Plating liquid pressurized at the circulating pump 54 flows into the storage tank 51. The flow rate of the plating liquid flowed into the storage tank 51 is adjusted at the storage tank 51, and the plating liquid flows into the plating processing tank 52 at a predetermined flow rate (by the weight of the liquid itself). Then, the plating liquid flows out of an outlet of the plating processing tank 52, and flows into the buffer tank 53. The flow rate of the plating liquid is raised again at the circulating pump 54, and the plating liquid flows into the storage tank 51.

[0007] During the circulation of the plating liquid, air bubbles may be generated in the plating liquid due to cavitation in the circulating pump. If the air bubbles adhere to a surface of a substrate, the air bubbles inhibit the growth of plating, and in the worst case, cause abnormal plating (abnormal thickness and defective shape of plating). In order to remove the air bubbles, the plating processing device is arranged so that the plating liquid pressurized at the circulating pump flows into the storage tank so as to release into the air the air bubbles in the liquid, and then the plating liquid flows into the plating processing tank 52 by the weight of the plating liquid itself without being pressurized, for example.

[0008] In the plating processing, the control of the flow volume of plating liquid and the control of the temperature of the plating liquid are also important for controlling the speed of metal deposition and the uniformity of the speed of metal deposition over the substrate, namely for controlling the plating thickness.

[0009] The flow volume of plating liquid is controlled by the float-type flowmeter 55 provided at the pipe from the storage tank 51 to the plating processing tank 52. The temperature of the plating liquid is controlled by the heat exchanging unit 57 (warm water is circulated inside bundled resin tubes so as to indirectly adjust the temperature) immersed in the buffer tank 53.

[0010] Due to the nature of the plating liquid, the plating processing may deposit plating metal on the plating liquid circulating pipes, the circulating pump, or the plating tank itself, for example, other than the predetermined position on the substrate. A part of the metal deposited on the position other than the predetermined position exfoliates from the deposited position and floats as foreign body in the plating liquid. The foreign body moves inside the plating processing device in accordance with the flow of the plating liquid. If the foreign body adheres to the surface of the substrate, the foreign body causes abnormal plating (abnormal thickness and defective shape of plating) in the worst case. To remove the foreign body, the filter 56 is provided after the circulating pump, for example. Further, the filter 56 is also provided directly before the plating processing tank 52, as shown in FIG. 3.

[0011] The foreign body floating in the plating liquid is removed by the filter, but the deposited matter adhering to the inner walls of the plating processing tank, etc. cannot be removed by the filter. Such deposited matter can cause defects such as the clogging of the pipes and the increase of the foreign body. Thus, the pipes and the plating processing tank, etc. are regularly washed using a halogenated chemical (such as aqua regia and iodine).

[0012] As described earlier, due to the nature of the plating liquid, metal is deposited on a portion where the plating liquid touches, such as the inner walls of the plating processing tank and pipes, in addition to the desired position. Since most of the metal deposited on the undesired portion adheres to the inner wall surfaces as in the plating processing tank, the inner walls are regularly washed using a halogenated chemical so as to remove the deposited metal.

[0013] A conventional problem is that it is difficult to easily and effectively prevent the plating material from being deposited as the foreign body in the plating processing.

DISCLOSURE OF INVENTION

[0014] In view of the foregoing problems, an object of the present invention is to provide a plating processing device capable of easily and effectively preventing a plating material from being deposited as foreign body in the plating processing.

[0015] In order to achieve the foregoing object, a plating processing device of the present invention which plates a plating target object by supplying plating liquid containing a plating material and causing the plating target object to touch the plating liquid, and which, if the plating material is deposited on an undesired position, removes the plating material from the undesired position using a removing agent is so arranged that at least a part of a portion touching the plating liquid is made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in same conditions.

[0016] With this arrangement, at least a part of a portion touching the plating liquid is made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in the same conditions.

[0017] Thus, when the removing agent is applied to the plating material that is deposited on the undesired position during the plating processing, the surface of the portion touching the plating liquid is not easily roughened if the portion is made of the above material instead of resin. As the surface is not easily roughened, accelerating the deposition of the plating material due to the irregularities caused by the roughness is prevented.

[0018] Therefore, it is possible to easily and effectively prevent the plating material from being deposited as foreign body in the plating processing.

[0019] Alternatively, the plating processing device of the present invention is arranged so as to include a plating processing tank for causing the plating target object to touch the plating liquid, wall surfaces of the plating processing tank being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in same conditions.

[0020] With this arrangement, wall surfaces of the plating processing tank are made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in the same conditions. Therefore, in addition to the effect of the foregoing arrangement, it is possible to more easily and effectively prevent the plating material from being deposited as foreign body in the plating processing.

[0021] Alternatively, the plating processing device of the present invention is arranged so as to include a plating processing tank for causing the plating target object to touch the plating liquid; and a plating processing tank pipe for conveying the plating liquid to the plating processing tank, wall surfaces of the plating processing tank pipe being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in same conditions.

[0022] With this arrangement, wall surfaces of the plating processing tank pipe are made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in the same conditions. Therefore, in addition to the effect of the foregoing arrangement, it is possible to more easily and effectively prevent the plating material from being deposited as foreign body in the plating processing.

[0023] Alternatively, the plating processing device of the present invention is arranged so as to include a plating processing tank for causing the plating target object to touch the plating liquid; and a storage tank for storing the plating liquid which is to be supplied to the plating processing tank, wall surfaces of the storage tank being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in same conditions.

[0024] With this arrangement, wall surfaces of the storage tank are made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in the same conditions. Therefore, in addition to the effect of the foregoing arrangement, it is possible to more easily and effectively prevent the plating material from being deposited as foreign body in the plating processing.

[0025] Alternatively, the plating processing device of the present invention is arranged so as to include a heating tank for containing the storage tank so as to heat the plating liquid in the storage tank using heat conduction.

[0026] With this arrangement, the plating liquid in the storage tank is heated using heat conduction. Accordingly, a member directly touching the plating liquid needs not be used as the heat exchanging unit for adjusting the temperature. Therefore, in addition to the effect of the foregoing arrangement, it is possible to easily and effectively prevent the plating material from being deposited as foreign body in the plating processing.

[0027] Alternatively, the plating processing device of the present invention is arranged so as to include a plating processing tank for causing the plating target object to touch the plating liquid; a plating processing tank pipe for conveying the plating liquid to the plating processing tank; and an ultrasonic flowmeter provided at a portion of the plating processing tank pipe, wall surfaces of the portion of the plating processing tank pipe, where the ultrasonic flowmeter is provided, being made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in same conditions.

[0028] With this arrangement, wall surfaces of the portion of the plating processing tank pipe where the ultrasonic flowmeter is provided are made of a material whose change rate of surface roughness in response to the removing agent is lower than resin when the material and the resin are measured in the same conditions. The ultrasonic flowmeter is provided at a position that does not touch the plating liquid. From there, the ultrasonic flowmeter can project an ultrasonic signal onto the plating liquid that flows inside the plating processing tank pipe, so as to measure the flow volume of the plating liquid in response to a signal reflected from the plating liquid. Therefore, in addition to the effect of the foregoing arrangement, it is possible to easily and effectively prevent the plating material from being deposited as foreign body in the plating processing.

[0029] For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is an explanatory diagram showing an embodiment of a plating processing device of the present invention.

[0031] FIG. 2 is an explanatory diagram showing change rates of surface roughness of materials in response to a halogenated chemical (iodine).

[0032] FIG. 3 is an explanatory diagram showing an arrangement of a conventional plating processing device.

BEST MODE FOR CARRYING OUT THE INVENTION

[0033] The following will explain an embodiment of the present invention with reference to FIGS. 1 and 2.

[0034] A conventional plating processing device is arranged so that components including a plating processing tank and pipes are made of resin material.

[0035] It was revealed that the surface roughness of the resin increases after repeatedly washed using a halogenated chemical (removing agent). FIG. 2 shows the results.

[0036] PVDF resin (Polyvinylidene fluoride) and PFA resin (Tetrafluoroethylene PerFluoroAlkylvinylether copolymer) are used for plating processing tank and a storage tank. After the PVDF resin and the PFA resin are immersed in iodine solution for a week at room temperature, the surface roughness (Ra: average roughness along the center line) of the resins increases by 70% to 158% with respect to the initial values.

[0037] In accordance with the changes in the surface roughness (increase of the surface roughness), the degree of activation of the irregularities that are formed on the surface changes. These irregularities supposedly serve as the cores to accelerate the deposition of metal which is the plating material.

[0038] In contrast, the surface roughness of hard glass and quartz glass (hereinafter referred to as glass) changes quite little, namely by 0% to 10%, after the glass is immersed in the same iodine solution, as shown in FIG. 2. As it is not possible to completely prevent metal from being deposited on a portion other than a predetermined position on a substrate (plating target position on a plating target object), regular washing using the halogenated chemical is indispensable. Therefore, the inner wall surfaces (surfaces touching the plating liquid) of the plating processing device need to be made of a material that is not roughened after repeatedly washed using the halogenated chemical.

[0039] The substrate to be plated should be plated in a uniform thickness. To achieve this, the control of the flow volume of plating liquid and the control of the temperature of the plating liquid are also important as described earlier.

[0040] The flow volume of plating liquid is conventionally measured by a float-type flowmeter. This type of flowmeter obtains a numeral value of the flow volume by floating a float in the plating liquid in such a manner that the float responds to the flow volume. Thus, the float itself obstructs the liquid flow. Further, incorporating the flowmeter complicates the arrangement of the pipes. This increases a liquid contact area (area that touches liquid) of the pipes with respect to the plating liquid. Accordingly, metal is easily deposited on portions such as the inside of the flowmeter and the bending portions of the pipes, as well as on the float itself. Consequently, the deposited matter accumulated in accordance with operating time can prevent the stable and correct measurement of the flow volume.

[0041] As a method to measure the flow volume of a chemical, there is a method to use ultrasonic waves which can measure the flow volume without touching the liquid. This method is to project an ultrasonic signal onto fluid in the pipes so as to read a signal transmitted from the fluid, thereby correctly measuring the flow rate and flow volume. This method cannot be used in the plating processing device whose pipes are made of resin, however, because the transmission signals cannot be transmitted and received correctly, as the inner wall surfaces of the resin pipes are roughened and metal is deposited on the roughened inner wall surfaces.

[0042] The temperature of the plating liquid is controlled by the heat exchanging unit in the buffer tank. The heat exchanging unit is prepared by bundling resin tubes. Since resin has poor heat conductivity, a large liquid contact area is required for desirable heat exchange. In combination with this structure of the heat exchanger, metal as the plating material is easily deposited on the heat exchanging unit made of resin.

[0043] The temperature of the plating liquid is preferably controlled directly before the plating processing tank. In the conventional plating processing device, however, metal is easily deposited on the heat exchanging unit because the heat exchanging unit is made of resin. For this reason, the plating liquid whose temperature is controlled at the buffer tank is pressurized at the circulating pump so as to pass through the filter before flowing into the storage tank. This increases the length of the pipes to such an extent as to cause the temperature drop of the plating liquid, thereby hindering the correct temperature control. This also increases the deposition of metal in accordance with the increase of the liquid contact area.

[0044] Further, in the conventional plating processing device, the filter 56 is also provided directly before the plating processing tank 52 as shown in FIG. 3. The filter 56 is provided to remove metal foreign body deposited on portions such as the storage tank 51, the flowmeter 55, and the inside of the pipes between the storage tank 51 and the plating processing tank 52. A predetermined pressure needs to be applied to the chemical in order to remove the foreign body using the filter. However, a pressurizing pump cannot be provided between the storage tank 51 and the plating processing tank 52, so as not to cause the cavitation. Thus, the chemical needs to be pressurized by being dropped (by its own weight). In order to obtain a predetermined pressure, it is necessary to place the storage tank 51 at a preferable height, and replace the filter in response to the clogging of the filter (decrease of the flow volume). This can increase the time and cost for maintenance.

[0045] (A) Minimizing the liquid contact area where the plating processing device touches the plating liquid and (B) arranging the plating processing device to be made of a material whose roughness does not change on the inner wall surfaces after regularly washed using a cleansing agent such as a halogenated chemical were revealed to be effective in preventing the deposition of metal (plating material) such as gold on a portion other than the predetermined position on the substrate (plating target position on the plating target object). With this, it is possible to remarkably reduce the foreign body generated in the plating processing device, reduce the number of filters conventionally required for removing the foreign body, and reduce the maintenance time and cost required for exchanging the filters.

[0046] As described earlier, the pipes, the plating processing tank, etc. need to be regularly washed using a halogenated chemical (such as aqua regia and iodine). Note that, the steps of forming a bump electrode of gold (Au) on a semiconductor integrated circuit will be outlined later.

[0047] As described earlier, FIG. 2 shows the change rates of the surface roughness of resin materials and glass materials used in the plating processing device, in the case where the halogenated chemical is used for washing. The resin materials do not significantly differ from the glass materials in terms of the surface roughness inside the pipes before washing (initial value). After immersed in a chemical (iodine) for a week, the surface roughness of the resin materials significantly changes such that the change rates are 70% to 158% with respect to the initial values. On the other hand, the changes rates of the glass materials are significantly small, namely 0% to 10%. It is preferable that the change rate of the surface roughness is as small as possible.

[0048] If the change rate of the surface roughness is high, namely if the inner walls have more irregularities, metal is easily deposited on the inner walls of the tanks and pipes, using the irregularities as the cores. Therefore, it is necessary to replace the tanks and pipes after carrying out one or several operations of the washing using the chemical.

[0049] The present embodiment is so arranged that the components of the plating processing device are made of glass which is a material that is not or almost is not roughened on the inner wall surfaces after repeatedly washed using a halogenated chemical. This prevents metal from being deposited on the inner wall surfaces.

[0050] As glass has higher heat conductivity than resin, the temperature of the plating liquid is controlled by immersing in a heating tank the storage tank made of glass. This eliminates the need for the heat exchanging unit, thereby remarkably reducing the liquid contact area with respect to the plating liquid. Further, it is possible to control the temperature of the plating liquid at a position closer to the plating processing tank, thereby stabilizing the processing temperature.

[0051] The deposition of metal is prevented inside the storage tank, the plating processing tank, and the pipe connecting the tanks, by making all of them with glass material. With this, the filter is not required between the storage tank and the plating processing tank, thereby eliminating the cost and time for maintenance such as the regular exchanging of the filter, etc. Further, the required difference in elevation between the storage tank and the plating processing tank is only such a difference as to cause the plating liquid to flow, thereby reducing the size of the plating processing device.

[0052] Further, by making the pipe with glass, the deposition of metal is prevented on the inner wall surfaces of the pipe. With this, it is possible to use an ultrasonic flowmeter that can measure the flow volume without touching the liquid, thereby simplifying the arrangement of the pipes.

[0053] In accordance with an embodiment of the present invention, the following will explain in detail a plating processing device used in the manufacturing process of semiconductor integrated circuits, with reference to the drawings.

[0054] Note that, the chemicals, etc. used in the following explanation are basically the same with the chemicals generally used for manufacturing semiconductor integrated circuits, and are used in the same conditions. Thus, their detailed description is omitted here expect for special cases.

[0055] First, the following will explain a method for manufacturing a semiconductor integrated circuit using the plating processing device of the present embodiment, namely, steps of forming a bump electrode on a semiconductor substrate using gold (Au) plating.

[0056] The semiconductor substrate, which is used as a substrate to be plated (plating target substrate) in the present embodiment, is arranged to mount a plurality of semiconductor integrated circuits, and is manufactured in the steps as described below.

[0057] An insulating film such as SiO2 is layered to have a predetermined thickness on an entire surface of a semiconductor substrate which mounts a semiconductor integrated circuit. The semiconductor substrate is a silicon wafer having a diameter of eight inches (approximately 200 mm), for example. Then, photolithography and insulating film etching are used to remove a predetermined portion of the insulating film.

[0058] Next, a metal thin film such as Al—Si is layered to have a thickness of approximately 1 μm on the entire surface of the wafer. Then, photolithography and metal thin film etching are used to form a pad electrode which is an output and input terminal. Here, the pad electrode has a size of approximately 60 μm×110 μm. Further, also formed here is wiring for mutually connecting elements such as transistors that are mounted on the surface of the wafer.

[0059] Next, an insulating film such as a SiN film, as a surface protection film, is layered to have a thickness of approximately 0.6 μm on the entire surface of the wafer. Then, a known method such as photolithography and insulating film etching are used to remove a predetermined portion of the surface protection film, so as to reveal the pad electrode. The opening portion of the surface protection film has a size of approximately 30 μm×80 μm, for example.

[0060] After this, as barrier metal, TiW is layered to have a thickness of approximately 0.2 μm and Au is layered to have a thickness of 2 μm. Then, photo resist is used to form a mask for plating. Using the mask, a known plating technique is used to deposit gold (Au) having a thickness of approximately 18 μm on a portion above the pad electrode so as to form a bump electrode. The size of the bump electrode is approximately 30 μm×80 μm, for example, as described above. The following will explain this in detail.

[0061] Namely, a metal thin film is layered to have a predetermined thickness on the entire surface of the wafer. The metal thin film prevents the reaction between (A) Au with which the bump electrode is to be formed and (B) Al or Al alloy with which the pad electrode is formed, and functions as so-called current film for electrolytic plating. The metal thin film is also called base metal. Note that, the base metal may be a single layer of metal thin film, but is usually a layered film in which a plurality of metals are layered, for preventing the reaction between Au and Al or Al alloy, or other reasons. The base metal is prepared by sequentially layering TiW to have a thickness of approximately 0.2 μm and Au to have a thickness of 0.2 μm.

[0062] Next, photo resist is applied to the entire surface of the wafer. Then, photolithography is used to remove a predetermined portion of the photo resist on the wafer, namely a portion of the photo resist that is on the opening portion of the surface protection film.

[0063] With these steps, the semiconductor substrate 4 is formed. The semiconductor substrate 4 is a substrate to be plated in the next, plating step. Note that, the photo resist remaining on the wafer functions as a mask in the plating step, so as to deposit plating metal on the opening portion of the photo resist.

[0064] Further, the following will explain the plating step of forming a bump electrode on the semiconductor substrate 4 using Au plating. The plating processing device of the present embodiment carries out the plating step.

[0065] First, a cathode electrode of the plating processing device is connected to a predetermined position on the base metal that is layered on the wafer of the semiconductor substrate. Then, the semiconductor substrate and an anode electrode (not shown) are immersed in plating liquid that fills a plating bath 2, in such a manner that the semiconductor substrate and the anode electrode substantially face each other in parallel. The power source applies a predetermined voltage across the semiconductor substrate and the anode electrode, so as to deposit plating metal on a predetermined portion of the semiconductor substrate, namely, on the opening portion of the photo resist, by an electrolytic plating method.

[0066] The voltage applied across the semiconductor substrate and the anode electrode should be appropriately set based on the size of the semiconductor substrate, the speed of plating the semiconductor substrate, and the like.

[0067] After the bump electrode is formed on the semiconductor substrate in the plating step, the photo resist is removed, and then a needless portion of the base metal is removed using the bump electrode as a mask. Then, predetermined steps are carried out to complete the semiconductor integrated circuit.

[0068] Next, a plating processing device of the present embodiment will be explained in detail.

[0069] FIG. 1 is a diagram schematically showing an arrangement of the plating processing device in accordance with the present embodiment.

[0070] FIG. 1 shows a storage tank 1, a plating processing tank 2, a buffer tank 3, a circulating pump 4, a filter 6, pipes (resin pipes) 8, pipes (glass pipes) 9, a heating tank 10, and an ultrasonic flowmeter (liquid noncontact type) 11.

[0071] The storage tank 1 has dimensions of approximately 400 mm (length)×100 mm (width)×300 mm (height). The plating processing tank 2 has dimensions of approximately 300 mm×100 mm×300 mm. The buffer tank 3 has dimensions of approximately 700 mm×500 mm×200 mm. Further, the heating tank 10 should have the height and the area of the base enough to contain the storage tank.

[0072] The plating processing device of the present embodiment shown in FIG. 1 is so arranged that the storage tank 1, the plating processing tank 2, and the buffer tank 3 are made of glass, namely hard glass or quartz glass, and the pipe 9 from the filter 6 to the storage tank 1, and the pipe (plating processing tank pipe) 9 from the storage tank 1 to the plating processing tank 2 are also made of glass.

[0073] Since portions from the filter 6 to the plating processing tank 2 are made of glass, an amount of metal deposited on the inner wall surfaces of the tanks and pipes is fairly small in these portions.

[0074] The pipes from the plating processing tank 2 to the filter 6 are made of resin. Because of this, metal is easily deposited on the inner walls of these pipes, but the filter 6 can prevent the deposited metal foreign body from flowing into the storage tank 1.

[0075] The buffer tank 3 may be made of resin, but this increases the liquid contact area with respect to the plating liquid. This accordingly increases the amount of the deposited metal, thereby accelerating the clogging of the filter 6. Therefore, it is preferable that the buffer tank 3 is also made of glass.

[0076] As the pipe 9 from the storage tank 1 to the plating processing tank 2 is made of glass, only a fairly small amount of metal is deposited on the inner wall surfaces of the pipe 9, so that an ultrasonic flowmeter can be used. Unlike the pipe to which the conventional float-type flowmeter is provided, the pipe from the storage tank 1 to the plating processing tank 2 is fairly simple. In combination with the effect of the use of glass, almost no metal is deposited in the pipe from the storage tank 1 to the plating processing tank 2, thereby eliminating the need for the filter that is provided directly before the plating processing tank in the conventional plating processing device. With this, the number of filters used in the plating processing device of the present embodiment is as about one-fifth as the number of filters in the conventional device. This reduces cost and time required for maintaining the plating processing device and reduces the size of the plating processing device.

[0077] Further, in the conventional plating processing device, deposited matter on the inner walls increases as the surface roughness on the inner wall surfaces of the pipes increases, because the pipes are made of resin material. This prevents a noncontact flowmeter such as an ultrasonic flowmeter from obtaining a stable numerical value. In the present embodiment, the deposition inside the pipes is reduced because the pipes are made of glass material, so that the noncontact flowmeter (ultrasonic waves) can stably measure the numerical value. Further, the noncontact flowmeter (ultrasonic waves) can eliminate obstructions within the pipes such as a float, thereby stabilizing the flow volume.

[0078] The heat conductivity of resin material such as polypropylene is 4.2 to 4.5×10−4 (cal/cm·sec·° C.), whereas the heat conductivity of glass material such as hard glass is 26.0 to 30.0×10−4 (cal/cm·sec·° C.). Namely, the heat conductivity of glass is one place larger than that of resin.

[0079] For this reason, the size of the heat exchanging unit for controlling the temperature of the plating liquid can be remarkably reduced if the heat exchanging unit is made of glass instead of resin. In combination with the effect of the heat exchanging unit having a small size, the glass heat exchanging unit can reduce the deposition of metal. With this, the temperature of the plating liquid, which can be controlled only at the buffer tank in the conventional plating processing device, can be controlled at the storage tank. This enables the correct control of the temperature of the plating liquid at a position closer to the plating processing tank.

[0080] The heat exchanging unit may be a common heat exchanging unit having a honeycomb shape in which thin tubes are bundled, and may be immersed in the plating liquid of the storage tank 1. In the present embodiment, by taking advantage of the good heat conductivity of glass of which the storage tank 1 is made, the temperature may be desirably controlled by directly inserting the storage tank 1 in the heating tank 10 that is additionally provided, as shown in FIG. 1, for example. In this case, no heat exchanging unit is immersed in the plating liquid, thereby further reducing the deposition of metal. The heating tank 10 may be filled with warm water, for example, with which the plating liquid in the storage tank 1 is warmed using heat conduction.

[0081] The foregoing explained an example where the pipe from the plating processing tank 2 to the buffer tank 3, and the pipe from the buffer tank 3 to the filter 6 via the circulating pump 4 are made of resin. These pipes may be made of glass without causing no particular problem in terms of preventing the metal deposition. But special consideration is required to use glass material for the pipe around the pump, because the glass may break due to the vibration of the pump, etc.

[0082] By changing the material of the other pipes and tanks to glass material, approximately 90% of the total liquid contact area with respect to the plating liquid can be made of glass material. With this, it is possible to prevent the deposition of metal on a portion other than a predetermined position on the surface of the semiconductor device (plating target position on the plating target object).

[0083] FIG. 1 shows an example where an outlet of the plating liquid from the storage tank 1 is provided at the bottom surface of the storage tank 1, but the outlet may be provided at a side surface of the storage tank 1. In this case, the same heating tank 10 can be also used to adjust the temperature.

[0084] Further, FIG. 1 shows an example where an inlet of the plating liquid into the plating processing tank 2 is provided at a side surface of the plating processing tank 2, but the inlet may be provided at the bottom surface of the plating processing tank 2 so as to control the thickness of the plating thickness. Of course, a plurality of inlets may be provided to the plating processing tank 2.

[0085] With this arrangement, it is possible to prevent metal from being deposited on the inside of the plating processing device. This prevents metal that is exfoliated from the inside of the device from attaching to semiconductor substrates, thereby reducing defects in semiconductor substrates. This can also reduce the number of filters used for removing the foreign body, thereby reducing the cost and time for maintenance.

[0086] Further, the temperature of the plating liquid can be controlled at a position closer to the plating processing tank, thereby correctly controlling the temperature on a substrate to be plated.

[0087] Here, a halogenated chemical is used as a cleansing liquid (removing agent). This is only an example in the case of gold (Au) plating. Alternatively, concentrated nitric acid and concentrated sulfuric acid may be used in Cu plating, and concentrated hydrochloric acid and dilute nitric acid may be used in Ni plating.

[0088] The foregoing explained the present invention in detail using the plating processing device for semiconductor integrated circuits as an example. However, the present invention can be applied to a plating processing device for manufacturing semiconductor devices other than semiconductor integrated circuits. For example, the present invention can be applied to a plating processing device used in the manufacturing process of compound semiconductors, and a plating processing device used in the manufacturing process of liquid crystal panels.

[0089] Note that, a device for manufacturing semiconductor integrated circuits of the present invention which includes a storage tank of a plating liquid, a plating processing tank to which the plating liquid flows from the storage tank, a buffer tank to which the plating liquid flows from the plating processing tank, a flowmeter which measures a flow volume of the plating liquid, a heat exchanging unit which controls the temperature of the plating liquid, a filter which removes foreign body from the plating liquid, a pump which circulates the plating liquid, and pipes which connects the tanks may be so arranged that portions touching the plating liquid are made of a material whose change rate of surface roughness in response to washing using a halogenated chemical is not more than 10% with respect to an initial value of the surface roughness.

[0090] Alternatively, the device of the present invention may be so arranged that hard glass or quartz glass is the material whose change rate of the surface roughness in response to the washing using the halognated chemical is not more than 10% with respect to the initial value.

[0091] Alternatively, the device of the present invention may be so arranged that the flowmeter of the plating liquid measures a liquid volume of the plating liquid using ultrasonic waves without touching the plating liquid.

[0092] Alternatively, the device of the present invention may be so arranged that a part of the pipes which connects the tanks is made of hard glass or quartz glass.

[0093] Alternatively, the device of the present invention may be so arranged that the temperature of the plating liquid is controlled at the storage tank.

[0094] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Industrial Applicability

[0095] The present invention relates to a plating processing device used in a device for manufacturing semiconductor integrated circuits, etc. In particular, the present invention can be used in manufacturing semiconductor integrated circuits to be mounted in electronic devices such as portable digital assistants, for which compactness, lightness in weight, and high density packaging are required.