Low-Temperature Deposition Process

Abstract

The present invention provides a process for the deposition of titanium silicon nitride (TiSiN) films on substrates, such as substrate surfaces on microelectronic devices. The process includes individually introducing compounds A, B, and C into a reaction zone under pulsed deposition conditions to provide a pulse sequence, the reaction zone being at about 250° C. to about 450° C., each compound being optionally followed by a purging step with an inert gas, A being selected from bis-t-amylethylenesilylene, SiI2H2, and SiI, B being TiCl4, and C being a nitrogen-containing reducing gas, and repeating the pulse sequence until a desired thickness of film is deposited. The process can be carried out at a relatively low temperature for the silicon precursor.

Description

[Technical Field]

[0001] The present invention relates generally to methodologies for forming certain thin films on microelectronic device substrates. In particular, the present invention relates to methodologies for the deposition of TiSiN films. [Background technology]

[0002] In the fabrication of integrated circuits, titanium nitride has attracted considerable interest given its relatively low resistivity and compatibility with CMOS (complementary metal oxide semiconductor) processes. Therefore, titanium nitride is often used as a liner barrier and can be deposited on silicon substrates. Such titanium nitride layers can be used as barrier layers to inhibit metal diffusion into regions beneath the barrier layer. A conductive metal layer, such as a copper- or tungsten-containing layer, is typically deposited on the titanium nitride layer. The titanium layer can be formed by chemical vapor deposition (CVD), atomic layer deposition (ALD), and / or physical vapor deposition (PVD). For example, a titanium nitride layer can be formed by reacting titanium tetrachloride with a reducing agent such as ammonia in a CVD process, or by reacting titanium tetrachloride with ammonia in a CVD process. A conductive material can then be deposited on the microelectronic device substrate. See, for example, U.S. Pat. No. 7,838,441. However, deposition of materials such as titanium nitride and titanium silicon nitride on microelectronic device substrates has been plagued by difficulties in the initiation of deposition, and the construction of film thickness based on the number of deposition sequences is relatively poor in the so-called initial nonlinear growth regime (see, for example, "Growth Mechanism and Continuity of Atomic Layer Deposited TiN films on Thermal SiO2," A. Satta, et al., Journal of Applied Physics, Volume 92, Number 12, pp. 7641-7646 (2002)).

[0003] For some microelectronic device substrates, films must be deposited at lower temperatures, e.g., 250°C to 450°C. At these low temperatures, it is particularly difficult to incorporate silicon into titanium silicon nitride films due to the reduced reactivity of silicon precursors at these lower temperatures. Therefore, there is a need for improved methodologies for the deposition of titanium-containing films, particularly titanium silicon nitride, where deposition is performed at lower temperatures to accommodate specific microelectronic device substrates. Summary of the Invention

[0004] In summary, the present invention provides a process for the deposition of titanium silicon nitride (TiSiN) films onto substrates, such as substrate surfaces on microelectronic devices. Surprisingly, the process can be carried out at relatively low temperatures for the silicon precursors described herein. In one process embodiment, a specific silicon precursor is introduced into the reaction zone, followed by titanium chloride or titanium iodide, followed by a nitrogen-containing reducing gas. An optional purge step after the introduction of each precursor with an inert gas may be utilized. At these relatively low temperatures, the process can achieve TiSiN films with approximately 30% Si, using a silicon precursor such as bis-t-amylethylenesilylene (TAS). The silicon doping level in the resulting TiSiN film can be adjusted (i.e., "tuned") to be higher or lower by utilizing more or fewer titanium nitride subcycles in the process (i.e., titanium chloride or titanium iodide, followed by a nitrogen-containing reducing gas), thereby reducing the overall relative percentage of silicon present in the film. [Brief explanation of the drawings]

[0005] [Figure 1] 1 is a graph of silicon nitride thickness in Angstroms versus the number of silicon nitride deposition subcycles, where a subcycle is defined by the introduction of TAS and an inert gas. The thickness is measured by X-ray fluorescence spectroscopy (XRF). [Figure 2] 1 is a graph of titanium nitride thickness in Angstroms versus titanium nitride subcycle number, where a subcycle is defined by the introduction of TiCl 4 , an inert gas, and a nitrogen-containing reducing gas (NH 3 ). [Figure 3] 1 is a graph of Si % as a function of TiSiN film thickness in Angstroms using TAS, TiCl 4 and NH 3 (combining the SiN and TiN thicknesses of FIGS. 1 and 2). [Figure 4] 1 is a graph of sheet resistance as a function of TiSiN film thickness in Angstroms using TAS, TiCl 4 , and NH 3 (combining the SiN and TiN thicknesses of FIGS. 1 and 2 ). [Figure 5] This figure shows a comparison of the crystallinity between pure TiN and TiSiN with similar thicknesses. X-ray diffraction (XRD) is used for this measurement. Pure TiN is polycrystalline with characteristic peaks, while TiSiN is amorphous with no noticeable peaks. TiN is deposited using TiCl4 and NH3. TiSiN is deposited using TAS, TiCl4, and NH3. [Figure 6] 1 is a graph of silicon nitride thickness in Angstroms versus the number of silicon nitride subcycles, where a subcycle is defined by the introduction of SiI2H2 and an inert gas. [Figure 7] 1 is a graph of titanium nitride thickness in Angstroms versus titanium nitride subcycle number, where a subcycle is defined by the introduction of TiCl 4 , an inert gas, and a nitrogen-containing reducing gas (NH 3 ). [Figure 8] 8 is a graph of Si % as a function of TiSiN film thickness in Angstroms using SiI 2 H 2 , TiCl 4 and NH 3 (combining the SiN and TiN thicknesses of FIGS. 6 and 7). [Figure 9] 8 is a graph of sheet resistance as a function of TiSiN film thickness in Angstroms using SiI 2 H 2 , TiCl 4 , and NH 3 (combining the SiN and TiN thicknesses of FIGS. 6 and 7). DETAILED DESCRIPTION OF THE INVENTION

[0006] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense including "and / or" unless the content clearly dictates otherwise.

[0007] The term "about" generally refers to a range of numbers that are considered equivalent to the recited value (e.g., having the same function or result). In many instances, the term "about" may include numbers that are rounded to the nearest significant figure.

[0008] Numerical ranges expressed using endpoints include all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0009] In a first aspect, the present invention provides a process for depositing a titanium silicon nitride (TiSiN) film on a microelectronic device substrate in a reaction zone, the process comprising: providing a pulse sequence by individually introducing compounds A, B, and C into a reaction zone under pulse deposition conditions, the reaction zone being at about 250°C to about 450°C, each compound optionally followed by a purge step with an inert gas, A being selected from bis-t-amylethylenesilylene, SiI2H2, and SiI4, B being selected from TiCl4 and TiI4, and C being a nitrogen-containing reducing gas; and repeating the pulse sequence until a desired thickness of film is deposited; The present invention provides a process including:

[0010] In one embodiment, the titanium silicon nitride film has a thickness of at least about 10 Å. In other embodiments, the titanium silicon nitride film has a thickness of at least about 20 Å, at least about 30 Å, at least about 40 Å, at least about 50 Å, at least about 60 Å, at least about 70 Å, at least about 80 Å, at least about 90 Å, or at least about 100 Å.

[0011] As a result of the process of the present invention, the relative level of amorphous character in the film increases, ie, the relative crystallinity decreases.

[0012] In the process of the present invention, the sequence from B to C (or "BC"), i.e., titanium chloride or titanium iodide followed by a nitrogen-containing gas, is referred to herein as a TiN (titanium nitride) subcycle. As noted above, if a lower overall silicon percentage is desired in the resulting TiSiN film, this TiN subcycle can be repeated a predetermined amount in the deposition process of the present invention to increase the amount of titanium nitride in the film, thus resulting in an overall concomitant decrease in silicon in the film as the titanium nitride is deposited. Thus, in one embodiment, the pulse sequence is A followed by B followed by C, with optional purge steps between the introduction of A, B, and C, followed by at least one titanium nitride subsequence of BC, which subsequence(s) can be introduced between each ABC pulse sequence, or any combination of sequences can be repeated one after the other, i.e., BC followed by BC, etc., until the overall ratio of ABC pulse sequences to CB subcycles is adjusted in a predetermined (empirical) manner, thus increasing the formation of titanium nitride layers and decreasing the corresponding overall silicon percentage in the titanium silicon nitride (TiSiN) film.

[0013] Thus, in one embodiment, the pulse deposition conditions include a multiple pulse sequence including a pulse of A followed by a pulse of B followed by a pulse of C, each pulse optionally followed by an inert gas purge. In another embodiment, the invention provides the above process further including the introduction of B and C to provide titanium nitride subcycles, each of which is optionally followed by an inert gas purge. In this manner, titanium silicon nitride films can be formed that are about 5 to about 50 weight percent silicon, based on the desired percentage of silicon and the predetermined number of titanium nitride subcycles for the A-B-C pulse sequence utilized in the vapor deposition. In certain embodiments, the percentage of silicon in the resulting film is from about 5 to about 10, from about 10 to about 15, from about 15 to about 20, from about 20 to about 25, from about 25 to about 30, from about 30 to about 35, from about 35 to about 40, from about 40 to about 45, from about 45 to about 50, from about 10 to about 40, or from about 15 to about 35 weight percent.

[0014] In certain embodiments, A is bis-t-amylethylenesilylene, B is TiCl, and C is ammonia. In other embodiments, A is SiIH. In other embodiments, A is SiI.

[0015] In certain embodiments, the pulse time for the compounds indicated above (i.e., the duration of precursor (A, B, and C) exposure to the substrate) ranges from about 0.1 to 60 seconds. If a purge step is utilized, the duration of the purge step is about 1 to 60 seconds, 1 to 4 seconds, or 1 to 2 seconds, depending on the particular tool and precursor compound identity utilized and the substrate on which deposition occurs. In other embodiments, the pulse time for introducing each compound into the reaction zone ranges from about 0.1 to 60 seconds or 20 to 40 seconds, again depending on the tool utilized. In other embodiments, the pulse time for each compound ranges from about 5 to about 10 seconds.

[0016] In one embodiment, the deposition conditions include a temperature of about 250°C to about 450°C. In particular embodiments, the deposition conditions include a pressure of about 0.5 to about 1000 Torr, or 1 to 30 Torr. In another embodiment, the deposition conditions include a temperature of about 350°C to about 450°C. The selection of a particular temperature and pressure will depend on the particular tool utilized for deposition, the identities of Compounds A, B, and C, and the substrate on which deposition occurs. In any event, the process of the present invention enables the formation of titanium silicon nitride films at surprisingly low temperatures.

[0017] Processes that can be used to form high purity thin metal, e.g., titanium-containing films include any suitable thermal evaporation technique, such as digital or pulsed CVD or ALD. Such evaporation processes can be used to form titanium silicon nitride films on at least one substrate surface of a microelectronic device, forming films having thicknesses of about 10 angstroms to about 2000 angstroms.

[0018] In the process of the present invention, the compounds described above can be reacted with the desired microelectronic device substrate in any pulsed regime, for example, in a single wafer CVD or ALD chamber, or in a furnace containing multiple wafers.

[0019] Alternatively, the process of the present invention can be carried out as an ALD or ALD-like process. As used herein, the term "ALD or ALD-like" refers to a process in which (i) each reactant is introduced sequentially into a reactor, such as a single-wafer ALD reactor, a semi-batch ALD reactor, or a batch furnace ALD reactor, or (ii) each reactant is exposed to the substrate or microelectronic device surface by moving or rotating the substrate to different sections of the reactor, with each section separated by an inert gas curtain, i.e., a spatial ALD reactor or a roll-to-roll ALD reactor.

[0020] As used herein, the term "nitrogen-containing reducing gas" includes a gas selected from hydrazine (N2H4), methylhydrazine, t-butylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and NH3.

[0021] The deposition methods disclosed herein may include one or more purge gases. Purge gases used to purge unconsumed reactants and / or reaction by-products are inert gases that do not react with the precursors. Exemplary purge gases include, but are not limited to, argon, nitrogen, helium, neon, and mixtures thereof. In certain embodiments, a purge gas, such as Ar, is supplied to the reactor at a flow rate ranging from about 10 to about 2000 sccm for about 0.1 to 1000 seconds to purge unreacted materials and any by-products that may remain within the reactor. Similarly, such inert gases may be used as carrier gases for the various precursors described above. Concentrations and flow rates may vary depending on the particular tool utilized.

[0022] Energy is applied to the precursor compound and the reducing gas, or a combination thereof, to induce the reaction and form a metal nitride-containing film on the microelectronic device substrate. Such energy can be provided by thermal or pulsed thermal methods.

[0023] As used herein, the term "microelectronic device" corresponds to a semiconductor substrate, including 3D NAND structures, flat panel displays, and microelectromechanical systems (MEMS), fabricated for use in microelectronic, integrated circuit, or computer chip applications. It should be understood that the term "microelectronic device" is not meant to be limiting in any way and includes any substrate that contains negative channel metal oxide semiconductor (nMOS) and / or positive channel metal oxide semiconductor (pMOS) transistors and that ultimately becomes a microelectronic device or microelectronic assembly. Such microelectronic devices contain at least one substrate that may be selected from, for example, silicon, SiO2, Si3N4, aluminum oxide, zirconium oxide, hafnium oxide, and other high-K oxides, OSG, FSG, silicon carbide, hydrogenated silicon carbide, silicon nitride, hydrogenated silicon nitride, silicon carbonitride, hydrogenated silicon carbonitride, boron nitride, antireflective coatings, photoresists, germanium, germanium-containing, boron-containing, Ga / As, flexible substrates, porous inorganic materials, metals such as copper and aluminum, and diffusion barrier layers such as, but not limited to, TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, or WN. The films are compatible with various subsequent processing steps, such as, for example, chemical mechanical planarization (CMP) and anisotropic etching processes. [Example]

[0024] Example 1 - Preparation of TiSiN films at 350°C Titanium silicon nitride films were deposited by ALD using titanium tetrachloride (TiCl), TAS*, and ammonia as precursor compounds. Each deposition cycle was performed according to the following sequence: 1. 0.2 second TAS pulse 2. 10-second pulse of argon 3. 0.2 second pulse of TiCl4 4. 10-second pulse of argon 5.1 second pulse of NH3 *TAS (bis-t-amylethylenesilylene) is an organosilylene.

[0025] As can be seen from the data shown in Figures 1 and 2, there is a nucleation delay for both TAS and TiCl4 when the individual silicon nitride and titanium nitride subcycles are less than 20, followed by approximately linear growth for both subcycles. As shown in Figures 3 and 4, a 1:1 test ratio results in a uniform Si doping level of approximately 30% for TiSiN films with thicknesses greater than 20 Å, which also become conductive. By adding more TiN subcycles, the Si doping level can be easily reduced to the desired target. As shown in Figure 5, a 42 Å titanium nitride film measured polycrystalline, while a 39 Å titanium silicon nitride film measured amorphous.

[0026] Example 2 - Preparation of TiSiN films at 350°C Titanium silicon nitride films were deposited by ALD using titanium tetrachloride (TiCl), SiI2H2, and ammonia as precursor compounds. Each deposition cycle was performed according to the following sequence: 1. 0.2 second pulse of SiI2H2 2. 10-second pulse of argon 3. 0.2 second pulse of TiCl4 4. 10-second pulse of argon 5.1 second pulse of NH3

[0027] As can be seen from the data shown in Figures 6 and 7, there was no nucleation delay for both SiI2H2 and TiCl4 for the individual silicon nitride and titanium nitride subcycles with linear growth. As shown in Figures 8 and 9, a 1:1 test ratio results in a uniform Si doping level of approximately 50% for the insulating TiSiN film. By adding more TiN subcycles, the Si doping level can be easily reduced to the desired target percentage.

[0028] Aspects In a first aspect, the present invention provides a process for depositing a titanium silicon nitride film on a microelectronic device substrate in a reaction zone, comprising: providing a pulse sequence by individually introducing compounds A, B, and C into a reaction zone under pulse deposition conditions, the reaction zone being at about 250°C to about 450°C, each compound optionally followed by a purge step with an inert gas, A being selected from bis-t-amylethylenesilylene, SiI2H2, and SiI4, B being selected from TiCl4 and TiI4, and C being a nitrogen-containing reducing gas; and repeating the pulse sequence until a desired thickness of film is deposited; The present invention provides a process including:

[0029] In a second aspect, the present invention provides the process of the first aspect, wherein the titanium silicon nitride film has a thickness of at least about 10 Å.

[0030] In a third aspect, the present invention provides the process of the first aspect, wherein the titanium silicon nitride film has a thickness of at least about 20 Å.

[0031] In a fourth aspect, the present invention provides the process of the first aspect, wherein the titanium silicon nitride film has a thickness of at least about 30 Å.

[0032] In a fifth aspect, the present invention provides the process of the first aspect, wherein the pulsed deposition conditions comprise a multiple pulse sequence, the pulse sequence comprising a pulse of A followed by a pulse of B followed by a pulse of C, each pulse optionally followed by a purging step with an inert gas.

[0033] In a sixth aspect, the invention provides the process of any one of the first to fifth aspects, wherein A is bis-t-amylethylenesilylene.

[0034] In a seventh aspect, the present invention provides the process of any one of the first to fifth aspects, wherein A is SiI2H2.

[0035] In an eighth aspect, the invention provides the process of any one of the first to seventh aspects, wherein B is titanium tetrachloride.

[0036] In a ninth aspect, the invention provides the process of any one of the first to eighth aspects, wherein the nitrogen-containing reducing gas is selected from ammonia; hydrazine; 1,1-dimethylhydrazine; and 1,2-dimethylhydrazine.

[0037] In a tenth aspect, the present invention provides the process of any one of the first to ninth aspects, wherein the nitrogen-containing reducing gas is ammonia.

[0038] In an eleventh aspect, the present invention provides the process of any one of the first to fourth aspects, wherein the pulsed deposition conditions further comprise the introduction of B and C to provide titanium nitride subcycles, each of B and C optionally followed by purging with an inert gas.

[0039] In a twelfth aspect, the present invention provides a method for preparing a plasma deposition process comprising the steps of: forming a plasma having a thickness of 100 Å; forming a plasma having a thickness of 100 Å; and forming a plasma having a thickness of 100 Å.

[0040] In a thirteenth aspect, the present invention provides the process of the fifth aspect, further comprising the introduction of B and C to provide a titanium nitride subcycle, each of B and C optionally followed by purging with an inert gas.

[0041] In a fourteenth aspect, the present invention provides the process of the twelfth aspect, wherein B is introduced followed by C.

[0042] In a fifteenth aspect, the invention provides the process of any one of the eleventh to thirteenth aspects, wherein the number of titanium nitride sub-cycles utilized in the process relative to the number of pulse sequences is predetermined to provide a titanium silicon nitride film having a desired weight percentage of silicon.

[0043] In a sixteenth aspect, the invention provides the process of any one of the eleventh to fourteenth aspects, wherein the percentage of silicon in the film is from about 5 to about 50 weight percent.

[0044] In a seventeenth aspect, the invention provides the process of any one of the eleventh to fourteenth aspects, wherein the percentage of silicon in the film is from about 15 to about 35 weight percent.

[0045] Having thus described several exemplary embodiments of the present disclosure, those skilled in the art will readily appreciate that still other embodiments may be made and used within the scope of the appended claims. Many advantages of the present disclosure, which are encompassed by this document, have been set forth in the foregoing description. It will be understood, however, that this disclosure is in many respects merely illustrative. The scope of the present disclosure is, of course, to be defined in the language in which the appended claims are expressed.

Claims

1. 1. A process for depositing a titanium silicon nitride film on a microelectronic device substrate in a reaction zone, comprising: and providing a pulse sequence by individually introducing compounds A, B, and C into the reaction zone under pulse deposition conditions, wherein the reaction zone is at about 250° C. to about 450° C., and each compound is optionally followed by a purging step with an inert gas; A is bis-t-amylethylenesilylene, SiI; ２ H ２ , and SiI ４ and B is selected from TiCl ４ and C is a nitrogen-containing reducing gas; repeating the pulse sequence until a desired thickness of the titanium silicon nitride film is deposited; said compounds A, B, and C are introduced in the order A, B, and C, with only optional purging steps between them, followed by at least one sequence of said B and C to provide a titanium nitride subcycle, each of said B and C optionally followed by a purging step; A process wherein the percentage of silicon in said titanium silicon nitride film is from about 30 to about 50 weight percent.

2. 2. The process of claim 1, wherein the pulsed deposition conditions comprise a plurality of pulse sequences, the pulse sequences comprising a pulse of A followed by a pulse of B followed by a pulse of C, each pulse optionally followed by a purge step with an inert gas.

3. A process for depositing a titanium silicon nitride film on a microelectronic device substrate in a reaction zone, comprising: introducing compounds A, B, and C individually into the reaction zone under pulsed deposition conditions to provide a pulse sequence, wherein the reaction zone is at about 250° C. to about 450° C., each compound is optionally followed by a purging step with an inert gas, and wherein A is bis-t-amylethylenesilylene, B is TiCl 4 , and C is a nitrogen-containing reducing gas; repeating the pulse sequence until a desired thickness of the titanium silicon nitride film is deposited; A process wherein said compounds A, B, and C are introduced in the order A, B, and C, with only optional purging steps between them, followed by at least one sequence of said B and C to provide a titanium nitride subcycle, each of said B and C optionally followed by a purging step.

4. A is SiI ２ H ２ 2. The process of claim 1, wherein

5. 4. The process of claim 1 or 3, wherein the nitrogen-containing reducing gas is ammonia.

6. The process of claim 3, wherein the percentage of silicon in the titanium silicon nitride film is from about 30 to about 50 weight percent.

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