Selectively depositing a silicon nitride film

Abstract

A method of depositing a silicon nitride film is presented. The method comprises heating a substrate having a first surface region of a first composition and a second surface region of a second composition. The substrate is exposed to an inhibitor that selectively bonds to the first surface region of the first composition. The substrate is exposed to a silicon-containing precursor and to a nitrogen-containing precursor to thermally deposit the silicon nitride film on the second surface region. The inhibitor inhibits deposition of the silicon nitride film on the first surface region.

Description

SELECTIVELY DEPOSITING A SILICON NITRIDE FILMBACKGROUND

[0001] Silicon nitride (SisN4, abbreviated as SiN herein) is a commonly used material in integrated circuits. SiN is typically deposited using plasma-enhanced processes, such as plasma-enhanced chemical vapor deposition (PECVD) or plasma enhanced atomic layer deposition (PEALD).SUMMARY

[0002] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0003] Examples are disclosed that relate to depositing silicon nitride films using thermal processes. One example provides a method of depositing a silicon nitride film. The method comprises heating a substrate having a first surface region of a first composition and a second surface region of a second composition. The substrate is exposed to an inhibitor that selectively bonds to the first surface region of the first composition. The substrate is exposed to a silicon-containing precursor and to a nitrogen-containing precursor to thermally deposit the silicon nitride film on the second surface region. The inhibitor inhibits deposition of the silicon nitride film on the first surface region.

[0004] In some examples, exposing the substrate to the silicon-containing precursor and to the nitrogen-containing precursor comprises cyclically exposing the substrate to the silicon-containing precursor and the nitrogen-containing precursor to form the silicon nitride film by thermal atomic layer deposition.

[0005] Alternatively or additionally, in some examples, the silicon-containing precursor comprises one or more compositions having a general formula of SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br, m+n = 6 and 1 < m < 6).

[0006] Alternatively or additionally, in some examples, the first surface region is a dielectric material, and the inhibitor is an aminosilane.

[0007] Alternatively or additionally, in some examples, the first surface region is a metal material, and the inhibitor is an alkylsilane.

[0008] Alternatively or additionally, in some examples, the nitrogen-containing precursor comprises one or more of ammonia, molecular nitrogen, hydrazine, or an amine.

[0009] Alternatively or additionally, in some examples, the method further comprises, after thermally depositing the silicon nitride film, exposing the substrate to a plasma post treatment.

[0010] Alternatively or additionally, in some examples, the silicon nitride film is a first silicon nitride film layer, and the method further comprises, after thermally depositing the first silicon nitride film layer, thermally depositing one or more additional silicon nitride film layers without removing the inhibitor.

[0011] Another example provides a processing tool. The processing tool comprises a processing chamber, a substrate support configured to hold a substrate disposed within the processing chamber, a substrate heater, and flow control hardware configured to control a flow of each of one or more processing chemicals into the processing chamber. The processing tool further comprises a controller configured to control the processing tool to heat a substrate having a first surface region of a first composition and a second surface region of a second composition, expose the substrate to an inhibitor that selectively bonds to the first surface region of the first composition, and expose the substrate to a silicon-containing precursor and to a nitrogen-containing precursor in absence of a plasma.

[0012] In some examples, exposing the substrate to the silicon-containing precursor and to the nitrogen-containing precursor comprises cyclically exposing the substrate to the silicon-containing precursor and the nitrogen-containing precursor to form a silicon nitride film by thermal atomic layer deposition.

[0013] Alternatively or additionally, in some examples, the silicon-containing precursor comprises one or more substances having a general formula of SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6).

[0014] Alternatively or additionally, in some examples, the inhibitor is an aminosilane.

[0015] Alternatively or additionally, in some examples, the inhibitor is an alkylsilane.

[0016] Alternatively or additionally, in some examples, the nitrogen-containing precursor comprises one or more of ammonia, molecular nitrogen, hydrazine, or an amine.

[0017] Alternatively or additionally, in some examples, the controller is further configured to control the processing tool to, after thermally depositing a silicon nitride film, expose the substrate to a plasma post treatment.

[0018] Alternatively or additionally, in some examples, the controller is further configured to control the processing tool to, after thermally depositing a silicon nitride film, thermally deposit one or more additional layers of silicon nitride film without removing the inhibitor.

[0019] Another example provides a method of depositing a silicon nitride film. The method comprises heating a substrate having a first surface region of a first composition and a second surface region of a second composition. The substrate is exposed to an inhibitor that selectively bonds to the first surface region of the first composition. The substrate is exposed to a silicon-containing precursor and to a nitrogen-containing precursor to thermally deposit a first silicon nitride film layer on the second surface region. The inhibitor inhibits deposition of the first silicon nitride film layer on the first surface region. After thermally depositing the first silicon nitride film layer, the substrate is exposed to the silicon-containing precursor and to the nitrogen-containing precursor to thermally deposit one or more additional silicon nitride film layers on the second surface region without removing the inhibitor to form the silicon nitride film. The substrate is exposed to a plasma post treatment.

[0020] In some examples, exposing the substrate to the silicon-containing precursor and to the nitrogen-containing precursor comprises cyclically exposing the substrate to the silicon-containing precursor and the nitrogen-containing precursor to form the silicon nitride film by thermal atomic layer deposition.

[0021] Alternatively or additionally, in some examples, the first surface region is a dielectric material, and the inhibitor is an aminosilane.

[0022] Alternatively or additionally, in some examples, the first surface region is a metal material, and the inhibitor is an alkylsilane.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1A illustrates structures formed in an inhibited silicon nitride (SisN4, abbreviated as SiN herein) deposition process that utilizes a plasma to form SiN, wherein the plasma removes an inhibitor from a substrate.

[0024] FIG. IB illustrates structures formed in an uninhibited SiN deposition process that utilizes a plasma to form SiN.

[0025] FIG. 2 illustrates structures formed in an example inhibited SiN deposition process that utilizes thermal atomic layer deposition (ALD) to form SiN, such that an inhibitor is not removed from a substrate.

[0026] FIG. 3 A shows a flow diagram illustrating the approach of FIG. 2

[0027] FIG. 3B and FIG. 3C illustrate selective SiN deposition.

[0028] FIG. 4A and FIG. 4B respectively show graphs indicating ammonia (NH3) saturation dose time and silicon precursor saturation dose time for thermal SiN deposition.

[0029] FIG. 4C shows a graph indicating film thickness over thermal ALD cycles for deposition of a Si precursor.

[0030] FIG. 5A is a bar graph indicating SiN etching rates (in Angstroms per minute) for SiN films formed using a variety of deposition conditions.

[0031] FIG. 5B is a bar graph showing some of the data of FIG. 5 A at a finer scale alongside additional post treatment data.

[0032] FIG. 6A is a bar graph indicating SiN film densities for SiN films formed using a variety of deposition conditions.

[0033] FIG. 6B is a bar graph indicating SiN film roughness for SiN films formed using a variety of deposition conditions.

[0034] FIG. 7 is a graph indicating SiN thickness vs deposition cycle for different substrates.

[0035] FIG. 8 shows a flow diagram illustrating an example process for selectively depositing silicon nitride on a substrate.

[0036] FIG. 9 shows an example of a processing tool that can be used to selectively deposit silicon nitride on a substrate.

[0037] FIG. 10 schematically shows an example computing system.DETAILED DESCRIPTION

[0038] It is often desirable to perform selective deposition processes that utilize inhibitors to selectively inhibit deposition on a substrate based upon substrate surface composition. Such processes are referred to herein as inhibited deposition processes. In an inhibited deposition process, a substrate with different material regions on its surface (e.g., a metal and a dielectric) is exposed to a molecular species, referred to herein as an inhibitor, that binds to a target material (e.g., one of a metal or a dielectric), but not to another material (e.g., the other of the metal or dielectric). After exposure to the inhibitor, the substrate is exposed to deposition chemicals for deposition of a film. The inhibitor prevents deposition of the film where the inhibitor has bound to the substrate. This allows the film to be selectively deposited in some substrate regions but not others, without having to use photolithographic patterning methods.

[0039] As mentioned above, current silicon nitride (SisN4, abbreviated as SiN herein) deposition methods often utilize a plasma to facilitate deposition. Plasmas can provide activation energy for the chemical reactions involved in SiN deposition, and also can help to densify a deposited SiN film.

[0040] However, plasma typically damages or destroys inhibitors, which thus significantly reduces the efficiency of selectively preventing deposition on the subsequent cycle. It is possible to re-apply the inhibitor every cycle (e.g., an ABC cycle of inhibitor — > precursor — > plasma), but this method is undesirable because it adds processing steps, and the inhibitor may not react the same on the plasma-treated surface as compared to the surface before plasma treatment. As such, plasma enhanced deposition processes that utilize selective inhibitors are not optimal due to the additional steps and costs.

[0041] Thus, examples are disclosed that relate to the selective deposition of SiN films using thermal processes. The disclosed example processes are compatible with inhibitors that can selectively inhibit film deposition based upon surface composition (e.g., oxide, nitride, and / or metal). Further, the disclosed examples can produce SiN films with desirable physical properties, such as suitably high wet etch resistances.

[0042] Briefly, the disclosed example thermal SiN deposition processes use a silicon halide as a silicon-containing precursor, and nitrogen-containing molecules such as ammonia, hydrazine, or a suitable amine, as a nitrogen-containing precursor. Silicon halides can be inhibited from adsorbing to a substrate surface by inhibitors commonlyused for selective deposition. Using thermal SiN deposition, rather than a plasma enhanced deposition process, can maintain inhibitor integrity during a deposition process, thereby maintaining deposition. A plasma post treatment can be utilized after deposition to densify and reduce a wet etch rate of the SiN film where desired.

[0043] SiN film deposition according to the disclosed examples can be performed using atomic layer deposition (ALD). In such a process, a SiN film is deposited in a layer-by-layer process by first exposing a substrate to the inhibitor, and then cyclically exposing the substrate to the silicon-containing precursor and then the nitrogen-containing precursor in the presence of sufficient thermal energy to cause conversion of the silicon-containing precursor to silicon nitride. Example deposition temperatures can include substrate heater temperatures within a range of 100 - 500 °C. In some such examples, a substrate heater can be heated to 300 - 450 °C or 400-500 °C during deposition. Examples of suitable processing chamber pressures include pressures within a range of 100 mTorr - 10 Torr. In other examples, temperatures and pressures outside of this range can be used.

[0044] As mentioned above, the use of a plasma post treatment can be used to densify the SiN film after deposition. Example film properties that can be achieved after deposition and plasma densification include densities of greater than 2.5 g / cmA3 and wet etch rates of less than 10 Angstroms / minute in 100: 1 dUF (dilute hydrogen fluoride). The plasma post treatment may further be useful to remove the inhibitor after deposition. The selectivity of deposition processes according to the disclosed examples has been demonstrated on several different material sets and patterns, as described herein.

[0045] Various silicon halides may be used as silicon-containing precursors in a thermal SiN deposition process according to the present disclosure. Examples include silicon bromides having the general formula SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6). Tetrabromosilane (Si Bn) is a more specific example of a suitable silicon halide. In some examples, silicon iodides and / or silicon chlorides also can be used as silicon-containing precursors in a SiN deposition process according to the present disclosure. More specific examples of silicon iodides and silicon chlorides include tetraiodosilane (SiLi) and tetrachlorosilane (SiCh), respectively.

[0046] The ability to get a high-quality, selective SiN film with thermal processing at reasonable temperatures is unexpected. Many silicon-containingprecursors for SiN deposition are solids and difficult to deliver in a vapor-phase processing system, or have low reactivity at reasonable ALD temperatures (and are therefore not compatible with some device materials or with molecular inhibitors). However, silicon halide precursors having the general formula SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6) may yield a high-quality SiN film, particularly after a plasma post treatment, at temperatures that are within the ranges given above.

[0047] FIG. 1A illustrates structures formed in an inhibited SiN deposition process that utilizes a plasma to form SiN. At 100, a silicon substrate 102 having a first surface region 104 comprising a first composition and a second surface region 106 comprising a second composition is exposed to an inhibitor 108. As shown at 110, inhibitor molecules selectively adsorb to second surface region 106 (shown as inhibitor layer 112), but not to first surface region 104. As an example, where second surface region 106 is a dielectric and first surface region 104 is a metal, the inhibitor can be an aminosilane. As another example, where second surface region 106 is a metal and first surface region 104 is a dielectric, the inhibitor can be an alkylsilane. Other example inhibitors can include various aldehydes, chlorosilanes / halosilanes, carboxylate / carboxylic acids, amidometallates, metal halides, ketones, isocyanides / isocyanates, thiocyanates, amines, phosphonic acids, and others.

[0048] After exposing the substrate to the inhibitor, the substrate is next exposed to a silicon-containing precursor 114, as shown at 110. Example silicon- containing precursors include silicon halides having the general formula SiXmHn (where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6).

[0049] As illustrated at 116, silicon-containing precursor 114 adsorbs, shown as adsorbed silicon-containing precursor layer 118, to first surface region 104, which is uninhibited, but not to second surface region 106 with inhibitor layer 112 on the surface. Next, at 116, substrate 102 is exposed to a nitrogen-containing precursor 120 (e.g., ammonia) in the presence of a plasma 122. Plasma 122 facilitates the conversion of adsorbed silicon-containing precursor layer 118 to a SiN layer 124, but also removes the inhibitor from second surface region 106 of substrate 102, as shown at 126.

[0050] As a result, a subsequent exposure of the substrate to silicon-containing precursor 114, at 126, results in the silicon-containing precursor adsorbing both to the previously-deposited SiN layer 124, shown as adsorbed silicon-containing precursorlayer 128, and to first surface region 104 region, shown as adsorbed silicon-containing precursor layer 130, as shown at 132. Further, at 132, substrate 102 is again exposed to nitrogen-containing precursor 120 (e.g., ammonia) in the presence of plasma 122. At 134, after exposure to nitrogen-containing precursor 120, a SiN layer 136 is deposited over both second surface region 106 and first surface region 104. As such, the selectivity of the SiN deposition is lost due to the inhibitor molecules of inhibitor layer 112 being removed by plasma 122 at 132.

[0051] FIG. IB shows an uninhibited plasma-enhanced SiN process that does not utilize an inhibitor, thereby forming a conformal SiN film. At 138, a silicon substrate 140 having a first surface region 142 and a second surface region 144 is exposed to a silicon-containing precursor 146. As shown at 148, an adsorbed silicon- containing precursor layer 150 is formed over both first surface region 142 and second surface region 144. Next, at 148, the adsorbed silicon-containing precursor layer 150 is exposed to a nitrogen-containing precursor 152 (e.g., ammonia) in the presence of a plasma 154. Plasma 154 facilitates the conversion of adsorbed silicon-containing precursor layer 150 to a SiN layer 156, as shown at 158. Thus, the uninhibited SiN deposition process does not selectively deposit SiN, but instead deposits SiN on both the first surface region 104 and the second surface region 106.

[0052] FIG. 2 illustrates structures formed in an example inhibited thermal SiN deposition process according to the present disclosure. As with FIG. 1A, at 200, a silicon substrate 202 having a first surface region 204 comprising a first composition and a second surface region 206 comprising a second composition is exposed to an inhibitor 208. Inhibitor molecules selectively adsorb to second surface region 206 (shown as inhibitor layer 210), but not to first surface region 204, as shown at 212.

[0053] In some examples, as described above, the inhibitor 208 can bond to second surface region 206. As an example, where second surface region 206 is a dielectric and first surface region 204 is a metal, the inhibitor can be an aminosilane. As another example, where second surface region 206 is a metal and first surface region 204 is a dielectric, the inhibitor can be an alkylsilane. Other example inhibitors can include various aldehydes, chlorosilanes / halosilanes, carboxylate / carboxylic acids, amidometallates, metal halides, ketones, isocyanides / isocyanates, thiocyanates, amines, phosphonic acids, and others. In other examples, the inhibitor 208 can bond to first surface region 204.

[0054] After exposing substrate 202 to inhibitor 208, at 212, substrate 202 is next exposed to a silicon-containing precursor 214. Again, example silicon-containing precursors include silicon halides having the general formula SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6). As illustrated at 216, silicon-containing precursor 214 adsorbs (shown as an adsorbed silicon-containing precursor layer 218) to the uninhibited portion of substrate 202, first surface region 204, but not to the inhibited portion of substrate 202, second surface region 206.

[0055] Next, at 216, substrate 202 is exposed to a nitrogen-containing precursor 220 (e.g., ammonia) in the presence of thermal energy, indicated at 222 with squiggly lines, but in the absence of a plasma (e.g., in a thermal atomic layer deposition process). As shown at 224, thermal energy 222, facilitates the conversion of adsorbed silicon- containing precursor layer 218 to a SiN layer 226 but allows inhibitor layer 210 to substantially remain adsorbed to second substrate region 206.

[0056] As a result, a subsequent exposure of the substrate to silicon-containing precursor 214 at 224, results in silicon-containing precursor 214 adsorbing to the previously-deposited SiN layer 226 (shown as an adsorbed silicon-containing precursor layer 228) on first substrate region 204 of substrate 202, but not to second substrate region 206 of substrate 202, as shown at 230.

[0057] Further, at 230, substrate 202 is again exposed to nitrogen-containing precursor 220 (e.g., ammonia) in the presence of thermal energy, indicated at 232 with squiggly lines, but in the absence of a plasma. At 234, after the exposure to nitrogencontaining precursor 220 at 230, a SiN layer 236 is deposited over first surface region 204. As such, the selectivity of the SiN deposition is retained. Additional silicon- containing precursor adsorption cycles and nitrogen-containing precursor exposure cycles can be performed to selectively grow a silicon nitride film of a desired thickness on first surface region 204 while maintaining second surface region 206 free of SiN deposition.

[0058] After thermally depositing the silicon nitride film, the substrate may be exposed to a plasma post treatment. The plasma post treatment may comprise exposure to nitrogen (N2) in the presence of a plasma. In some examples, the plasma post treatment may comprise NH3 / N2 or N2 / He. In some examples, another inert gas may be used instead of helium. In examples where multiple deposition cycles are performed, the plasma post treatment may be performed at the end of the deposition cycles, orperiodically during deposition (e.g., after every 3-10 cycles). Where a plasma post treatment is done periodically during deposition, the inhibitor can again be deposited before depositing additional SiN film layers.

[0059] Various surfaces can be selectively inhibited to perform selective SiN deposition according to the present disclosure. Examples include tungsten, copper, cobalt, molybdenum, ruthenium, titanium nitride, tantalum nitride, silicon, silicon nitride, silicon oxide, silicon oxynitride, silicon oxycarbide, and aluminum oxide.

[0060] FIG. 3 A shows an example flow diagram 300 summarizing the approach described with regard to FIG. 2. First, at 302, a substrate having two or more regions of different composition optionally can be exposed to a pretreatment that aids in differentiating the regions. The pretreatment can comprise, for example, exposing the substrate to a hydrogen plasma, an oxygen plasma, nitrogen containing plasma, ammonia containing plasma, and / or helium containing plasma. Example mixtures of different gases in a pretreatment plasma can include He / EE, He / Ch, He / Eh / Ch, H2 / O2, etc. Such a gas mixture composition may be selected based on the specific surfaces in the substrate pattern.

[0061] The substrate is then, at 304, exposed to an inhibitor that selectively bonds to some, but not all, surfaces of the substrate. FIGS. 3B and 3C show an inhibitor selectively bonding to some, but not all surfaces of a substrate. In the example of FIG. 3B, an inhibitor 305 adsorbs to a planar polysilicon portion 306 of a substrate 308, but not to a SiN surface 310, such that a SiN layer 311 can be selectively deposited on SiN surface 310. In the example of FIG. 3C, an inhibitor 312 adsorbs to a surface of a polysilicon layer 313 within a recessed feature 314 of a substrate 315, but not to a SiN surface 316, such that SiN layer 317 can be deposited selectively on SiN surface 316. In other examples, an aminosilane inhibitor may adhere to polysilicon and prevent SiN deposition thereupon. Such inhibition can be performed on both planar surfaces and non-planar surfaces including sidewalls. Even following the removal of native oxide (e.g., with an HF -based etch) an aminosilane inhibitor can selectively bind to Si over SiN.

[0062] Next, at 318, SiN deposition is selectively performed using thermal ALD at temperatures between 300 °C and 450 °C or 400 °C and 500 °C. In other examples, temperatures outside of this range can be used. The SiN deposits on uninhibited substrate surfaces, but not on inhibited substrate surfaces.

[0063] Next, at 320, a plasma post treatment can be performed. The plasma post treatment can densify the SiN film, and also can remove any residual inhibitor. In this way, the polysilicon contact within the structure can be maintained free of SiN deposition, while the rest of the structure is covered with a SiN film.

[0064] FIG. 4A and FIG. 4B respectively show graphs indicating NH3 saturation dose time (graph 400) and Si precursor saturation dose time (graph 410) for thermal SiN deposition according to the disclosed examples. Two different ellipsometers were used to determine film thickness, shown in FIGS. 4A-B as circle data points and diamond data points. The solid vertical lines of graph 400 and graph 410 indicate the dose times at which the growth no longer increases above a threshold rate. This indicates where the film demonstrates self-limiting growth, thus characterizing the process as an ALD process. Purge time, temperature, cycle number, pressure, and Si precursor dose time were kept constant in FIG. 4A. In FIG. 4B, the same conditions were held constant, except that ammonia dose time was kept constant, rather than the Si precursor.

[0065] FIG 4C shows a graph 420 indicating film thickness over thermal ALD cycles for deposition of a Si precursor. Graph 420 was generated using the saturated conditions indicated in graphs 400 and 410. The dose and purge times are kept constant over a sequence of deposition cycles. In this example, an approximately linear increase in thickness is shown as a function of cycle number, consistent with traditional ALD processes that do not have a CVD component.

[0066] FIG. 5A illustrates a bar graph 500 indicating mean wet etching rate (in Angstroms per minute) for a variety of reaction conditions and temperatures. Samples were etched with an aqueous dHF concentration of 100: 1. At 502A and 502B, depositions were performed at 300 °C, and samples had either no pre / post treatment (502A), or had post treatment with NH3 / N2 plasma (502B). At 504A-D, depositions were performed at 400 °C, and samples had either no pre / post treatment (504A), pretreatment with NH3 / NH2 plasma only (504B), post treatment with NH3 / N2 plasma only (504C), or pre and post treatments (shown at 504D of FIG. 5B). Pre-treatments can be used, for example, to modify the selectivity of an inhibitor, as mentioned above. At 506A and 506B, depositions were performed at 450 °C, and samples had either post treatment with NH3 / N2 plasma only (506A), or pre-treatment and periodic post treatment with NH3 / N2 plasma (506B). At 508, a PECVD-deposited SiN film (e.g., notdeposited with thermal ALD) was used. At 510 samples underwent deposition at 400 °C and were exposed to ISh / He post treatment.

[0067] FIG. 5B is a bar graph 520 showing a finer etch rate scale for some of the data (504A-C and 508) depicted in FIG. 5 A. Further, at 512A-C samples underwent deposition at 400 °C and were exposed to ISh / He post treatment for various times, for example, short (512A), medium (512B), and long (512C). In these examples, a lower etch rate is desirable, e.g., comparable to the PECVD-deposited SiN film (as shown at 508), and thus a highly etch-resistant film.

[0068] As shown in FIG. 5A, etch resistance increases with deposition temperature. Further as shown at 506A and 506B, for samples deposited at 450 °C, adding post treatment with NH3 / N2 significantly decreases the etch rate. Upon deposition at 400 °C, post treatment with ISh / He (512A-C) significantly reduced etch rate as compared to post treatment with NH3 / N2 (504C and 504D). This post treatment enables the avoidance of patterning steps to achieve selective deposition. Further, the inhibitor, deposition, and post treatment phases can all be performed in vapor phase.

[0069] FIG. 6A is a bar graph 600 indicating film density in g / cc for a variety of deposition conditions. Film density was determined by X-Ray reflectivity. FIG. 6B is a bar graph 610 indicating film roughness in Angstroms for a variety of deposition conditions at 400 °C. Film roughness was also determined by X-Ray reflectivity. Deposition conditions include: SiN deposition only (612a, 612b); NH3 / N2 post treatment (614a, 614b); N2 / He post treatment (616a, 616b); NH3 / N2 post treatment plus an additional annealing time at 400 °C (618a, 618b); and NH3 / N2 periodic post treatment (e.g., not after every cycle) (620a, 620b). An increase in density and decrease in roughness is seen for N2 / He post treatment as compared to NH3 / N2 post treatment. Without wishing to be bound by theory, the favorable SiN film qualities demonstrated in FIGS. 5A-5B and 6A-6B for the N2 / He post treatment may arise from exposure to ultraviolet (UV) light emitted by helium atoms in a plasma.

[0070] FIG. 7 is a graph 700 indicating SiN thickness vs deposition cycles for different substrates. Substrates included SiN (solid black line), SiCh (dashed line), and poly-Si (dashed dotted line). As shown, film growth in the presence of the inhibitor was selective for SiN. Further, film deposited on SiN increased as a function of cycle number.

[0071] FIG. 8 shows a flow diagram illustrating an example method 800 for depositing a silicon nitride film. Method 800 can be performed by a processing toolcontrolled by a controller comprising one or more computing devices. Example processing tools are described in more detail below with regard to FIG. 9. Example computing devices are described herein and with regard to FIG. 10.

[0072] At 810, method 800 comprises heating a substrate having a first surface region of a first composition and a second surface region of a second composition.

[0073] At 820, method 800 comprises exposing the substrate to an inhibitor that selectively bonds to the first surface region of the first composition. In some examples, the first surface region is a dielectric material, and the inhibitor is an aminosilane. In some examples, the first surface region is a metal material, and the inhibitor is an alkylsilane.

[0074] At 830, method 900 comprises exposing the substrate to a silicon- containing precursor and to a nitrogen-containing precursor to thermally deposit the silicon nitride film on the second surface region, wherein the inhibitor inhibits deposition of the silicon nitride film on the first surface region. In some examples, exposing the substrate to the silicon-containing precursor and to the nitrogen-containing precursor comprises cyclically exposing the substrate to the silicon-containing precursor and the nitrogen-containing precursor to form the silicon nitride film by thermal atomic layer deposition. In some examples, the silicon-containing precursor comprises one or more substances having a general formula of SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6). In other examples, the silicon-containing precursor can be a chlorosilane or an iodosilane. In some examples, the nitrogen-containing precursor comprises one or more of ammonia, molecular nitrogen, hydrazine, or an amine. In some examples, the method further comprises, after thermally depositing the silicon nitride film, thermally depositing one or more additional layers of the silicon nitride film without removing the inhibitor. Optionally, at 840, method 800 comprises, after thermally depositing the silicon nitride film, exposing the substrate to a plasma post treatment.

[0075] FIG. 9 shows an example of a processing tool 900 that can be used to thermally deposit a SiN film on a substrate in an inhibited SiN film deposition process. Processing tool 900 also can be used to deposit a selective inhibitor, to perform a plasma post treatment, and / or to perform a pretreatment on a substrate prior to inhibitor deposition. Processing tool 900 is an example of a processing tool that can implementthe methods described herein with reference to the figures above. In other examples, one or more of the processes described herein can be performed using a different tool.

[0076] Processing tool 900 comprises a processing chamber 902 and a substrate support 904 within the processing chamber. Substrate support 904 is configured to support a substrate 906 disposed within processing chamber 902. Substrate support 904 can comprise a pedestal, such as an electrostatic chuck pedestal, or any other suitable substrate-supporting structure. Substrate support 904 can comprise a substrate heater 908.

[0077] The processing tool 900 further comprises a showerhead 910 to introduce processing chemicals into the processing chamber 902. In other examples, a processing tool can comprise a nozzle or other apparatus for introducing gas into processing chamber 902, as opposed to or in addition to a showerhead. The processing tool 900 further comprises flow control hardware 912. Flow control hardware 912 connects processing gas source(s) to the processing chamber to allow a flow of each of one or more processing gases to be controlled. In the depicted example, the flow control hardware 912 connects an inhibitor source 914, a silicon-containing precursor source 916, a nitrogen-containing precursor source 918, one or more inert gas source(s) 920, and one or more plasma treatment gas sources 922. The flow control hardware 912 can include any suitable components. Examples include mass flow controllers, valves, and conduits.

[0078] The inhibitor source 914 comprises any suitable inhibitor that can be introduced into a processing chamber in a gas phase (including liquid or solid materials that can be vaporized for introduction into the processing chamber) for selectively adsorbing to a substrate surface. Example inhibitors include silicon-containing inhibitors, such as alkylsilane inhibitors and aminosilane inhibitors. In examples, where the substrate comprises a metal, the inhibitor may be an alkysilane inhibitor. In examples where the substrate comprises a dielectric material, the inhibitor may be an aminosilane inhibitor. Examples of alkylsilane inhibitors include n-octadecylsilane, tridecylsilane, dodecylsilane, undecyl silane, decylsilane, decan-4-ylsilane, nonylsilane, nonan-4-ylsilane, octan-2-ylsilane, octylsilane, heptylsilane, heptan-4-ylsilane, (tridecafluoro- 1,1, 2, 2-tetra-hydrooctyl)silane, or 10-undecenylsilane. Examples of aminosilane inhibitors include bisdiethylaminosilane, diisopropylaminosilane, bis(t- butylamino) silane (BTBAS), di-sec-butylaminosilane, tris(dimethylamino)silane (3DMAS) dimethylamino trimethyl silane, dimethylamino dimethyl silane,dimethylamino triethyl silane, diethylamino trimethylsilane, n- butyldimethyl(dimethylamino)silane, n-propyldimethyl(dimethylamino)silane, or triisopropyldimethylaminosilane. In some examples, inhibitor source 914 comprises an inhibitor that is in a condensed phase at standard pressure and temperature. In such examples, inhibitor source 914 can comprise a flow-over-vapor delivery system, a vaporizer delivery system, charged volume delivery system, a mole delivery device, or other suitable delivery system to volatilize the condensed phase inhibitor. This enables the delivery of the inhibitor precursor in a vapor phase.

[0079] The silicon-containing precursor source 916 comprises a volatile or volatilizable SiN film precursor that can adsorb to a substrate surface and then be chemically converted into a film, such as by using atomic layer deposition. In some examples, the film precursor source 916 contains a dielectric film precursor that is in a condensed phase at standard pressure and temperature. In such examples, film precursor source 916 can comprise a flow-over vapor delivery system, a vaporizer delivery system, a charge volume delivery system, a mole delivery device, or other suitable delivery system to volatilize the condensed phase dielectric film precursor. For forming silicon nitride dielectric films, example dielectric film precursors can comprise one or more substances having a general formula of SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6). Tetrabromosilane is one example of such a material. Other example silicon- containing precursors include tetraiodosilane, tetrabromosilane, tetrachlorosilane, and other silicon halides.

[0080] Nitrogen-containing precursor source 918 can comprise one or more of ammonia, hydrazine, and amines. Inert gas source(s) 920 can comprise any suitable inert gas. Examples include helium, neon, argon, krypton, and xenon. In some applications, such as in processing steps that do not utilize a plasma, nitrogen gas can be used as an inert gas. In some examples, one or more additional inert gas sources can be included, each providing a different inert gas. Plasma treatment source 922 can comprise one or more of ammonia, nitrogen, helium, argon, etc.

[0081] The processing tool 900 further comprises an exhaust system 935. The exhaust system 935 is configured to exhaust gases from the processing chamber 902. The exhaust system 935 can comprise any suitable hardware, including one or more low vacuum pumps and one or more high vacuum pumps.

[0082] The processing tool 900 further comprises a radiofrequency power source 936 configured to generate a plasma. In the depicted example, the radiofrequency power source 936 is electrically connected to the substrate support 904. The showerhead 910 is electrically connected to ground as a counter electrode. In other examples, the radiofrequency power source 936 can be connected to showerhead 910 and the substrate support 904 can be electrically connected to ground.

[0083] The processing tool 900 further includes a matching network 938 for impedance matching of the radiofrequency (RF) power source 936. The radiofrequency power source 936 can be configured to provide RF energy of any suitable frequency and power. Example frequencies include 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 90 MHz. In some examples, the radiofrequency power source 936 is configured to operate at a plurality of different frequencies and / or powers. Examples of lower frequencies include frequencies of 3 MHz and below. The lower frequency radiofrequency energy component can comprise a power of up to 6500 W. In processing chambers with multiple processing stations, the lower frequency radiofrequency energy component can comprise a power of up to 6500 W per processing station. Examples of suitable high-frequency radiofrequency frequencies include frequencies within a range of 3 MHz to 300 MHz. The higher frequency radiofrequency energy component can comprise a power of up to 6500 W (per processing station). In other examples, a processing tool can provide for other radiofrequency powers and / or frequencies.

[0084] Controller 940 is operatively coupled to the substrate heater 908, flow control hardware 912, exhaust system 935, and radiofrequency power source 936. Controller 940 is configured to control various functions of the processing tool 900 to pretreat and / or selectively deposit a film on a substrate surface, such as a dielectric film. For example, controller 940 is configured to operate substrate heater 908 to heat a substrate to a desired temperature, the substrate having a first surface region of a first composition and a second surface region of a second composition. Controller 940 is also configured to operate flow control hardware 912 to control a flow of inhibitor from inhibitor source 914 into processing chamber 902, the inhibitor configured to selectively bond to the first surface region of the first composition. Controller 940 is further configured to operate flow control hardware 912 to control a flow of silicon- containing precursor from the silicon-containing precursor source, and to control a flow of nitrogen-containing precursor from the nitrogen-containing precursor source. In this way, the substrate is exposed to a silicon-containing precursor and to a nitrogen-containing precursor to thermally deposit the silicon nitride film on the second surface region, wherein the inhibitor inhibits deposition of the silicon nitride film on the first surface region.

[0085] Controller 940 can comprise any suitable computing system. FIG. 10 schematically shows a block diagram non-limiting example of a computing system 1000 that can enact one or more of the methods and processes described above. Computing system 1000 is shown in simplified form. Computing system 1000 may take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and / or network accessible server computers.

[0086] Computing system 1000 includes a logic machine 1002 and a storage machine 1004. Computing system 1000 may optionally include a display subsystem 1006, input subsystem 1008, communication subsystem 1010, and / or other components not shown in FIG. 10.

[0087] Logic machine 1002 includes one or more physical devices configured to execute instructions. For example, the logic machine may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform a task, implement a data type, transform the state of one or more components, achieve a technical effect, or otherwise arrive at a desired result.

[0088] The logic machine may include one or more processors configured to execute software instructions. Additionally or alternatively, the logic machine may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. Processors of the logic machine may be single-core or multi-core, and the instructions executed thereon may be configured for sequential, parallel, and / or distributed processing. Individual components of the logic machine optionally may be distributed among two or more separate devices, which may be remotely located and / or configured for coordinated processing. Aspects of the logic machine may be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

[0089] Storage machine 1004 includes one or more physical devices configured to hold instructions 1012 executable by the logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of storage machine 1004 may be transformed — e.g., to hold different data.

[0090] Storage machine 1004 may include removable and / or built-in devices. Storage machine 1004 may include optical memory (e.g., CD, DVD, HD-DVD, Blu- Ray Disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and / or magnetic memory (e.g., hard-disk drive, floppy-disk drive, tape drive, MRAM, etc.), among others. Storage machine 1004 may include volatile, nonvolatile, dynamic, static, read / write, read-only, random-access, sequential-access, location-addressable, file- addressable, and / or content-addressable devices.

[0091] It will be appreciated that storage machine 1004 includes one or more physical devices. However, aspects of the instructions described herein alternatively may be propagated by a communication medium (e.g., an electromagnetic signal, an optical signal, etc.) that is not held by a physical device for a finite duration.

[0092] Aspects of logic machine 1002 and storage machine 1004 may be integrated together into one or more hardware-logic components. Such hardware-logic components may include field-programmable gate arrays (FPGAs), program- and application-specific integrated circuits (PASIC / ASICs), program- and applicationspecific standard products (PSSP / ASSPs), system-on-a-chip (SOC), and complex programmable logic devices (CPLDs), for example.

[0093] When included, display subsystem 1006 may be used to present a visual representation of data held by storage machine 1004. This visual representation may take the form of a graphical user interface (GUI). As the herein described methods and processes change the data held by the storage machine, and thus transform the state of the storage machine, the state of display subsystem 1006 may likewise be transformed to visually represent changes in the underlying data. Display subsystem 1006 may include one or more display devices utilizing virtually any type of technology. Such display devices may be combined with logic machine 1002 and / or storage machine 1004 in a shared enclosure, or such display devices may be peripheral display devices.

[0094] When included, input subsystem 1008 may comprise or interface with one or more user-input devices such as a keyboard, mouse, or touch screen. In some examples, the input subsystem may comprise or interface with selected natural user input (NUI) componentry. Such componentry may be integrated or peripheral, and the transduction and / or processing of input actions may be handled on- or off-board. Example NUI componentry may include a microphone for speech and / or voice recognition, and an infrared, color, stereoscopic, and / or depth camera for machine vision and / or gesture recognition.

[0095] When included, communication subsystem 1010 may be configured to communicatively couple computing system 1000 with one or more other computing devices. Communication subsystem 1010 may include wired and / or wireless communication devices compatible with one or more different communication protocols. As non-limiting examples, the communication subsystem may be configured for communication via a wireless telephone network, or a wired or wireless local- or wide-area network. In some examples, the communication subsystem may allow computing system 1000 to send and / or receive messages to and / or from other devices via a network such as the Internet.

[0096] It will be understood that the configurations and / or approaches described herein are exemplary in nature, and that these specific examples or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and / or described may be performed in the sequence illustrated and / or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

[0097] The subject matter of the present disclosure includes all novel and non- obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and / or properties disclosed herein, as well as any and all equivalents thereof.

Claims

CLAIMS:

1. A method of depositing a silicon nitride film, the method comprising: heating a substrate having a first surface region of a first composition and a second surface region of a second composition; exposing the substrate to an inhibitor that selectively bonds to the first surface region of the first composition; and exposing the substrate to a silicon-containing precursor and to a nitrogencontaining precursor to thermally deposit the silicon nitride film on the second surface region, wherein the inhibitor inhibits deposition of the silicon nitride film on the first surface region.

2. The method of claim 1, wherein exposing the substrate to the silicon-containing precursor and to the nitrogen-containing precursor comprises cyclically exposing the substrate to the silicon-containing precursor and the nitrogen-containing precursor to form the silicon nitride film by thermal atomic layer deposition.

3. The method of claim 1, wherein the silicon-containing precursor comprises one or more compositions having a general formula of SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br, m+n = 6 and 1 < m < 6).

4. The method of claim 1, wherein the first surface region is a dielectric material, and wherein the inhibitor is an aminosilane.

5. The method of claim 1, wherein the first surface region is a metal material, and wherein the inhibitor is an alkylsilane.

6. The method of claim 1, wherein the nitrogen-containing precursor comprises one or more of ammonia, molecular nitrogen, hydrazine, or an amine.

7. The method of claim 1, further comprising: after thermally depositing the silicon nitride film, exposing the substrate to a plasma post treatment.

8. The method of claim 1, wherein the silicon nitride film is a first silicon nitride film layer, and further comprising: after thermally depositing the first silicon nitride film layer, thermally depositing one or more additional silicon nitride film layers without removing the inhibitor.

9. A processing tool, comprising: a processing chamber; a substrate support configured to hold a substrate disposed within the processing chamber; a substrate heater; flow control hardware configured to control a flow of each of one or more processing chemicals into the processing chamber; and a controller configured to control the processing tool to: heat a substrate having a first surface region of a first composition and a second surface region of a second composition; expose the substrate to an inhibitor that selectively bonds to the first surface region of the first composition; and expose the substrate to a silicon-containing precursor and to a nitrogencontaining precursor in absence of a plasma.

10. The processing tool of claim 9, wherein exposing the substrate to the silicon- containing precursor and to the nitrogen-containing precursor comprises cyclically exposing the substrate to the silicon-containing precursor and the nitrogen-containing precursor to form a silicon nitride film by thermal atomic layer deposition.

11. The processing tool of claim 9, wherein the silicon-containing precursor comprises one or more substances having a general formula of SiXmHn(where X is one of Cl, I, and Br, m+n = 4 and 1 < m < 4), and Si2XmHn(where X is one of Cl, I, and Br m+n = 6 and 1 < m < 6).

12. The processing tool of claim 9, wherein the inhibitor is an aminosilane.

13. The processing tool of claim 9, wherein the inhibitor is an alkylsilane.

14. The processing tool of claim 9, wherein the nitrogen-containing precursor comprises one or more of ammonia, molecular nitrogen, hydrazine, or an amine.

15. The processing tool of claim 9, wherein the controller is further configured to control the processing tool to: after thermally depositing a silicon nitride film, expose the substrate to a plasma post treatment.

16. The processing tool of claim 9, wherein the controller is further configured to control the processing tool to: after thermally depositing a silicon nitride film, thermally deposit one or more additional layers of silicon nitride film without removing the inhibitor.

17. A method of depositing a silicon nitride film, the method comprising: heating a substrate having a first surface region of a first composition and a second surface region of a second composition; exposing the substrate to an inhibitor that selectively bonds to the first surface region of the first composition; exposing the substrate to a silicon-containing precursor and to a nitrogencontaining precursor to thermally deposit a first silicon nitride film layer on the second surface region, wherein the inhibitor inhibits deposition of the first silicon nitride film layer on the first surface region; after thermally depositing the first silicon nitride film layer, exposing the substrate to the silicon-containing precursor and to the nitrogen-containing precursor to thermally deposit one or more additional silicon nitride film layers on the second surface region without removing the inhibitor to form the silicon nitride film; and exposing the substrate to a plasma post treatment.

18. The method of claim 17, wherein exposing the substrate to the silicon- containing precursor and to the nitrogen-containing precursor comprises cyclically exposing the substrate to the silicon-containing precursor and the nitrogen-containing precursor to form the silicon nitride film by thermal atomic layer deposition.

19. The method of claim 17, wherein the first surface region is a dielectric material, and wherein the inhibitor is an aminosilane.

20. The method of claim 17, wherein the first surface region is a metal material, and wherein the inhibitor is an alkylsilane.

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