DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0024] One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0025] Turning now to the drawings, and referring initially to FIG. 1, a block diagram depicting an exemplary processor-based system, generally designated by reference numeral 10 , is illustrated. The system 10 may be any of a variety of types such as a computer, pager, cellular phone, personal organizer, control circuit, etc. In a typical processor-based device, a processor 12 , such as a microprocessor, controls the processing of system functions and requests in the system 10 . Further, the processor 12 may comprise a plurality of processors which share system control.

[0026] The system 10 typically includes a power supply 14 . For instance, if the system 10 is a portable system, the power supply 14 may advantageously include permanent batteries, replaceable batteries, and/or rechargeable batteries. The power supply 14 may also include an AC adapter, so the system 10 may be plugged into a wall outlet, for instance. The power supply 14 may also include a DC adapter such that the system 10 may be plugged into a vehicle cigarette lighter, for instance.

[0027] Various other devices may be coupled to the processor 12 depending on the functions that the system 10 performs. For instance, a user interface 16 may be coupled to the processor 12 . The user interface 16 may include buttons, switches, a keyboard, a light pen, a joystick, a mouse, and/or a voice recognition system, for instance. A display 18 may also be coupled to the processor 12 . The display 18 may include an LCD display, a CRT, LEDs, and/or an audio display, for example. Furthermore, an RF sub-system/baseband processor 20 may also be couple to the processor 12 . The RF sub-system/baseband processor 20 may include an antenna that is coupled to an RF receiver and to an RF transmitter (not shown). A communications port 22 may also be coupled to the processor 12 . The communications port 22 may be adapted to be coupled to one or more peripheral devices 24 such as a modem, a printer, a computer, or to a network, such as a local area network, remote area network, intranet, or the Internet, for instance.

[0028] The processor 12 controls the functioning of the system 10 by implementing software programs. Generally, a memory sub-system, as described below in regard to FIG. 2 , is coupled to the processor 12 to store and facilitate execution of various programs. For instance, the processor 12 may be coupled to the volatile memory 26 which may include Dynamic Random Access Memory (DRAM) and/or Static Random Access Memory (SRAM). The processor 12 may also be coupled to the non-volatile memory 28 . The non-volatile memory 28 may include a read-only memory (ROM), such as an EPROM, and/or flash memory to be used in conjunction with the volatile memory or a high capacity memory such as a tape or disk drive memory. The size of the ROM is typically selected to be just large enough to store any necessary operating system, application programs, and fixed data. The volatile memory 26 on the other hand, is typically quite large so that it can store dynamically loaded applications and data.

[0029] A portion of the memory sub-system, such as the volatile memory 26 , is depicted in FIG. 2 . Generally, a memory controller 30 is generally provided to facilitate access to the storage devices. While the present embodiment illustrates the memory controller 30 as existing in the memory sub-system, the memory controller 30 may be in the processor 12 or may exist in a completely separate chip, as can be appreciated by those skilled in the art. The memory controller 30 may receive requests to access the memory devices via one or more processors, such as the processor 12 , via peripheral devices, such as the peripheral device 24 , and/or via other systems. As previously discussed, the memory controller 30 is generally tasked with facilitating the execution of the requests to the memory devices and coordinating the exchange of information, including configuration information, to and from the memory devices.

[0030] The memory sub-system may include a plurality of slots or ranks 32 A- 32 H which are configured to operably couple a memory module, such as a dual-inline memory module (DIMM), to the memory controller 30 via one or more memory buses. Each DIMM generally includes a plurality of memory devices such as DRAM devices capable of storing data. The memory buses may include a memory data bus 34 to facilitate the exchange of data between each memory device and the memory controller 30 . The volatile memory 26 also includes a command bus 36 on which address information such as command address (CA), row address select (RAS), column address select (CAS), write enable (WE), bank address (BA), and chip select (CS), for example, may be delivered for a corresponding request.

[0031] As one skilled in the art will recognize, various components of the system 10 and its associated memory sub-system, including the processor 12 , the non-volatile memory 28 , and the volatile memory 26 , incorporate numerous semiconductor devices. These semiconductor devices, typically dies fabricated by applying assorted deposition and etching processes to a silicon wafer substrate, rely upon the integrity and purity of the particular layers of which they are composed to function properly. In a given semiconductor device, one or more of the integral layers may be a titanium-containing thin film which functions to enhance conductivity, to prevent interdiffusion, to facilitate adhesion between layers of the semiconductor device, etc. Impurities within the titanium-containing thin film may prevent the thin film from performing these functions properly and may thereby impair the functioning of the semiconductor device.

[0032] Impurities within the thin film include the byproducts of the deposition reaction used to deposit the titanium-containing thin film, typically chlorine and chloride. In particular, the titanium deposition reaction commonly uses titanium tetrachloride, TiCl ₄ , as a precursor that generates chlorine and chloride byproducts that contaminate both the titanium-containing thin film and the reaction chamber itself. Contamination of the reaction chamber allows for the contamination of future reaction products. Using the exemplary technique described in detail below, a layer of titanium or titanium-containing film is deposited upon a wafer such that chlorine and chloride contamination of the film and of the reaction chamber is significantly reduced.

[0033] To perform the deposition of the titanium-containing thin film, a CVD or ALD reactor 40 is advantageously used, as illustrated in FIG. 3 . Hydrogen and a titanium source gas, typically a titanium halide such as titanium tetrachloride, titanium tetrabromide, or titanium tetraiodide, are introduced into the reaction chamber 42 through a shower head 44 . If desired, a carrier gas, such as argon or helium, may be added to the reactant gases. The gases may or may not be pre-mixed. The gases are generally introduced through the shower head 44 to achieve good dispersion of the gases, but the gases can be introduced by other means.

[0034] Desired reaction pressures are maintained by conventional pressure control components, including a pressure sensor 46 , a pressure switch 48 , an air operating vacuum valve 50 , and a pressure control valve 52 . The carrier gas and the byproduct gas given off during the reaction escapes from the reaction chamber 42 through an exhaust vent 54 . These gases pass through a particulate filter 56 , and gas removal may be facilitated by a roots blower 58 .

[0035] In the reactor chamber 42 , a substrate holder 60 is heated to a temperature of less than 700° C. In fact, temperatures may be in the range of 200 to 400° C., with pressures in the range of 0.1 to 6.0 Torr. Heating may be achieved through the use of halogen lamps 62 , so that the silicon wafer 64 is heated by convection. Plasma may also be introduced into the reactor chamber 42 to enhance certain deposition reactions, i.e. PECVD, such as those reactions for depositing Ti or TiSi _x .

[0036] As a result of this process, a chemical reaction occurs which results in the deposition of a titanium-containing film along the exposed surfaces of the wafer 64 . The thin films which are typically deposited by this process are generally less than 3000 Å thick and generally deposited during an exposure period greater than 200 seconds. In a deposition process where titanium tetrachloride is employed as the titanium precursor, the reaction can be characterized as TiCl ₄ +2(H ₂ )→Ti+4(HCl). As mentioned above, the titanium-based reaction may be modified to employ other halides as the titanium source gas, such as titanium tetrabromide or titanium tetraiodide, instead of titanium tetrachloride. The chemical reaction in those instances can be characterized as TiBr ₄ (or TiI ₄ )+2(H ₂ )→Ti+4(HBr) (or 4(HI)).

[0037] Optionally, a reducing agent can be introduced into the reaction chamber 42 along with the titanium precursor and hydrogen. When this reducing agent is ammonia, the titanium-containing film which is deposited onto the wafer 64 is composed principally of titanium nitride, and the reaction can be characterized by 6(TiCl ₄ )+8(NH ₃ )→6(TiN)+N ₂ +24(HCl) at temperatures between 400° C. and 700° C. When the reducing agent is a silane, the titanium containing film which is deposited onto the wafer 64 is composed principally of elemental titanium and titanium silicide, and the reaction can be characterized by 3(TiCl ₄ )+2(H ₂ )+2(SiH ₄ )→2(Ti)+TiSi ₂ +12(HCl). Various other titanium-based reactions using similar titanium precursors will be known to those skilled in the art for depositing other titanium containing thin films, such as those comprising titanium boride and titanium boronitride.

[0038] While these assorted titanium-based reaction are effective for depositing titanium-containing films, the byproducts of the deposition reactions, typically chlorides, such as HCl, and chlorine from incomplete reactions, contaminate the deposited thin film. The resulting contamination may compromise the effectiveness of the titanium-containing thin film as a barrier or conductor, or the chlorine or chloride may diffuse out to contaminate layers adjacent to the titanium-containing thin film. Either of these consequences of contamination may adversely affect the function of the semiconductor device. Additionally the chlorine and chloride byproducts continue to contaminate the reaction chamber 42 after the deposition reaction, thereby contaminating future deposition reactions and products.

[0039] To reduce or limit the effects of this chlorine-based contamination, it is therefore desirable to remove or adsorb the chlorine and chloride byproducts during the deposition process to prevent the contamination of the thin layer product. To this end, it is desirable to include within the reaction chamber 42 a component composed of a material that has a greater affinity for chlorine and/or chlorides than the titanium-containing thin film and those films comprising the remainder of the device. Such high affinity materials include, but are not limited to carbon, silicon, manganese, group I or group II elements, amines (such as pyridine), phosphines, and other Lewis bases. Such an adsorptive component may thereby remove chlorine and/or chloride from the reaction area and thereby reduce the amount of chlorine and chloride contamination. For instance, one possibility would be to construct or coat a component of the reaction chamber 42 , such as the shower head 44 or the substrate holder 60 , with such an adsorptive material. Another possibility would be to dispose a removable component or device composed of such a material within the reaction chamber 42 . In some instances, the high affinity material, such as manganese, carbon or silicon, may be heated to a temperature higher than that of the reaction chamber 42 in order to increase the oxidation reaction rate of these materials with halogen byproducts, thereby enhancing their adsorption rate.

[0040] Referring once again to FIG. 3 , such a removable component is depicted in the form of removable liners 66 secured to the walls 68 of the reaction chamber 42 . Fasteners 70 may be employed to secure the removable liners 66 and may be integral or separate from the walls 68 or the removable liner 66 and may constitute hooks, clips, screws, or any other type fastener capable of securing the removable liner 42 to the reaction chamber walls 68 . A close-up of the association of the removable liner 66 , the fastener 70 and the reaction chamber wall 68 is shown in FIG. 3 a , representing the region of FIG. 3 outlined by the dotted line.

[0041] The removable liners 66 are at least partly composed of a material that has a greater affinity for chlorine and/or chlorides than the titanium-containing thin film and those films comprising the remainder of the device. For example, the removable liner 66 may be composed, at least in part, of the carbon, silicon, manganese, group I or group II elements, or amine. These adsorptive materials, whether incorporated into a removable liner 66 or a component of the reactor 40 , act to pull the chlorine out of the gas phase, thereby reducing the amount of chlorine available to contaminate the titanium-containing thin layer. Where carbon, manganese or silicon is used as the removable liner 66 or component of the reactor 40 , these materials may be heated to a temperature greater than that of the reaction chamber in order to increase their adsorption rate of chlorine or other halogens.

[0042] For example, if an amine, such as pyridine, is chemically bonded to the surface of the removable liner 66 , the amine will adsorb chlorides, such as HCl, to form amine hydrochloride salts. The amine may be chemically attached to a substrate, such as a zeolite which will be the surface of the removable liner 66 or other component of the reactor 40 . Carbon also will bind free chlorine and may comprise the removable liner 66 or a portion of the liner. Manganese may be used to coat the removable liner 66 and will form stable halide with free chlorine. However, at the temperatures and pressures typical of titanium-containing thin film deposition reactions, manganese does not react with chlorine.

[0043] One consideration in designing an adsorptive component, including the removable liner 66 , is that the component may be desired to provide sufficient surface area to provide adsorption and removal of chlorine and chlorides for a useful time period. In the case of a removable component, such as the liner 66 , it may be desirable to be able to leave the removable liner 66 in place within the reaction chamber 42 for a minimum of a week and preferably for a month or longer. Numerous configurations of the removable liner 66 may be employed to increase the surface area of the removable liner 66 to provide the type of duration envisioned. For example, referring now to FIG. 4, a corrugated liner 72 is depicted which effectively increases surface area to lengthen the period that the removable liner 66 may be left in the reaction chamber 42 . The depth, pitch, number, and texture of the corrugations of the corrugated liner 72 may be modified to increase its effective surface area. Alternately, referring now to FIG. 5, a porous liner 74 with perforations is depicted. The circumference, depth and number of the pores of the porous liner 74 may be adjusted to provide increased effective surface area. Referring now to FIG. 6, a mesh liner 76 is depicted which also acts to increase the effective surface area presented within the reaction chamber 42 . The spacing, thickness, and depth of the mesh of the mesh liner 76 may be modified to increase the effective surface area of the removable liner 66 .

[0044] As will be recognized by those skilled in the art, various other modifications may be made to the removable liners 66 discussed above, i.e. corrugated, porous, and mesh, to increase their effective surface areas. Likewise other configurations of the removable liner 66 may be employed which also provide an enhanced surface area. The discussion of corrugated, porous, and mesh configurations of the removable liner 66 is merely demonstrative and is not intended as an exhaustive list of possible modifications for increasing surface area. Any removable component performing the chlorine and/or chloride adsorptive functions described above may be used in the present technique, regardless of whether the surface area of such a component is increased or in what manner the surface area of such a component is increased.

[0045] An alternative to employing a removable liner 66 or other removable component is depicted in FIG. 7 . In FIG. 7 , an adsorptive coating 78 is applied to the interior wall 68 of the reaction chamber 42 . Unlike the removable liner 66 , the adsorptive coating 78 is intended to remain within the chamber indefinitely. A close-up view of the adsorptive coating 78 and its configuration with the reaction chamber wall 68 can be seen in FIG. 7 a , representing the portion of FIG. 7 outlined by the dotted line. The adsorptive coating 78 may comprise the same materials discussed above and may be applied so that it possesses a roughened texture to increase the available surface area for adsorption of chlorine-based contaminants.

[0046] After a period of use, the removable liner 66 , the adsorptive coating 78 , or any other adsorptive components employed may be regenerated to restore their adsorptive capacity.

[0047] Such regeneration may include heating the removable liner 66 , the adsorptive coating 78 , or other component to a sufficiently high enough temperature to free chlorine-based contaminants, which may then be flushed out of the reaction chamber. Silicon based adsorptive materials, whether employed in a removable liner 66 , an adsorptive coating 78 , or another component, may be regenerated by etching off the titanium silicide or titanium nitride which will form on the silicon. By means of these regenerative processes, the removable liner 66 , the adsorptive coating 78 , or the other adsorptive components may be used to reduce chlorine-based contamination for an extended period.

[0048] Use of these chlorine adsorptive components discussed above reduces chlorine and chloride contamination of the reaction chamber 42 and of the titanium-containing film product by one to two orders of magnitude. Prior to this technique, chlorine-based contamination levels might be as high as 10% chlorine in the deposited titanium-containing films and are never less than 2% to 3% in the deposition temperature range of 200° C. to 350° C. Use of these adsorptive structures, however, reduces chlorine-based contamination to levels of 0.1% to 1% chlorine in a titanium-containing film deposited in the temperature range of 200° C. to 350° C. Further, use of these chlorine-adsorbing components should work for any ALD or CVD based deposition of metal halides where a low halide content is desired in the deposited film. In other words, the materials discussed above should attract other halides, such as fluorine as well as chlorine. Therefore, if reactant gases such as TaF ₅ or WF ₆ are used, for example, the removable liner 66 or the adsorptive coating 78 will attract fluorine or halide-based contaminants as well.

[0049] While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.