Silicon precursor compounds and method for forming silicon-containing films

Abstract

The present invention provides certain silicon precursor compounds that can be used to form silicon-containing films in the manufacture of semiconductor devices, and more specifically, compositions and methods for forming such silicon-containing films, such as films containing silicon dioxide or silicon nitride.

Description

[Technical Field]

[0001] Generally speaking, the present invention relates to a method and precursor for depositing silicon-containing films onto the surface of microelectronic devices. [Previous Technology]

[0002] In semiconductor manufacturing, thin (e.g., <1000 nanometers thick) passivation layers of chemically inert dielectric materials (such as silicon nitride (Si3N4), silicon oxynitride (SiOxNy), silicon carbide (SiC), silicon carbonitride (SiCN), silicon carbide (SiCO), and / or silicon dioxide (SiO2)) are widely used in microelectronic device structures as structural elements of multilayer devices, such as sidewall spacers, diffusion masks, oxide barriers, trench isolation coatings, intermetallic dielectric materials, passivation layers, insulators, and etch stop layers.

[0003] Chemical vapor deposition (CVD) is an attractive method for forming silicon-containing films. A particularly desirable approach is CVD processes involving low deposition temperatures (e.g., below approximately 450°C), but this requires the availability of suitable silicon precursor compounds for this purpose. In some cases, higher deposition temperatures can be considered when the thermal budget of the integrated circuit allows. In these cases, temperatures >450°C can be used to achieve the desired dielectric film. Therefore, precursors for forming silicon-containing films that can be used at such higher temperatures are needed. In particular, liquid silicon precursors with good thermal stability, high volatility, and reactivity with the substrate surface are required. [Summary of the Invention]

[0004] This invention generally relates to the formation of silicon-containing films in the manufacture of semiconductor devices, and more specifically to compositions and methods for forming such silicon-containing films. In one particular embodiment, it has been found that the precursor bis(trichlorosilyl)ethane can be used to form silicon dioxide and silicon nitride films with high purity and at high growth rates (i.e., about 1.5 Å / cycle at 600°C using ozone as the oxidizing gas and about 1.47 Å / cycle at 725°C using ammonia). Furthermore, as shown in the information provided herein, the wet etch rate (WER) of the films produced by this precursor is significantly improved compared to silicon dioxide films formed using bis(tert-butylamino)silane (BTBAS) with ozone and silicon nitride films formed using hexachlorodisilane (HCDS). It was discovered that bis(trichlorosilyl)ethane is thermally stable at temperatures above 600°C, thus making it suitable for use in the relatively high-temperature atomic layer deposition process required for high-purity silicon dioxide films.

Implementation Method

[0014] As used in this specification and the accompanying claims, unless otherwise expressly indicated herein, the singular forms “a,” “an,” and “the” include a plurality of indicators. As used in this specification and the accompanying claims, unless otherwise expressly indicated herein, the term “or” is generally used in the sense that it includes “and / or.”

[0015] The term "about" generally refers to a range of values ​​that are considered equivalent to the listed values ​​(e.g., having the same function or result). In many cases, the term "about" may include values ​​rounded to the nearest significant figure.

[0016] The range of values ​​represented by endpoints includes all values ​​contained in that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4 and 5).

[0017] In the first embodiment, the present invention provides a compound of formula (I): (I), wherein each R1 is independently selected from hydrogen or C1-C4 alkyl, and each R2 is independently selected from chlorine, bromine, iodine, hydrogen, or C1-C4 alkyl, wherein at least two R2 are selected from chlorine, bromine, or iodine. In one embodiment, each R1 is hydrogen. In another embodiment, each R2 is selected from chlorine, bromine, or iodine. In yet another embodiment, each R1 is hydrogen and each R2 is chlorine, i.e., a compound of the following formula, denoted herein by the initials "BTCSE".

[0018] Compounds of formula (I) can be used as precursors in films deposited by vapor deposition, particularly on the surfaces of microelectronic devices. In some embodiments, the film also contains nitrogen and / or oxygen and / or carbon. Therefore, in a second embodiment, the present invention provides a method for forming a silicon-containing film on a surface of a microelectronic device, the method comprising introducing at least one compound of formula (I) into the surface in a reaction chamber under vapor deposition conditions.

[0019] As used herein, the term "silicon-containing film" refers to films such as silicon dioxide, silicon nitride, silicon oxynitride, silicon carbide, silicon carbonitride, silicon oxycarbonitride, low-k silicon-containing thin films, high-k gate silicate films and low-temperature silicon epitaxial films.

[0020] In some embodiments, the vapor deposition conditions include reaction conditions referred to as chemical vapor deposition, pulsed chemical vapor deposition, and atomic layer deposition. Preferably, the vapor deposition conditions do not utilize plasma. In the case of pulsed chemical vapor deposition, a series of alternating pulses of precursor compounds and co-reactants can be used to accumulate film thickness to the desired endpoint with or without an intermediate (inert gas) purge step.

[0021] In some embodiments, the pulse time of the precursor compound (i.e., the duration of exposure of the precursor to the substrate) ranges from about 1 to 30 seconds. When a cleanup step is used, the duration is about 1 to 20 seconds or 1 to 30 seconds. In other embodiments, the pulse time of the co-reactant ranges from 5 to 60 seconds.

[0022] In one embodiment, the vapor deposition conditions include temperatures of about 100°C to about 1000°C, such as about 450°C to about 1000°C, about 400°C to about 600°C, or above 600°C to about 900°C; and pressures of about 0.5 to about 1000 Torr. In another embodiment, the vapor deposition conditions include temperatures of about 100°C to about 800°C, such as about 425°C to about 525°C, 500°C to about 750°C, or about 625°C to about 725°C.

[0023] The above compounds can be used to form high-purity silicon-containing thin films using any suitable vapor deposition technique (such as CVD, digital (pulsed) CVD, ALD, and pulsed plasma processes). Such vapor deposition processes can be used to form silicon-containing films on microelectronic devices having a thickness of about 20 angstroms to about 2000 angstroms, such as about 20 angstroms to about 1000 angstroms or about 100 angstroms to about 1000 angstroms. For example, such silicon-containing films have a thickness of about 100 angstroms to about 250 angstroms or about 200 angstroms to about 500 angstroms.

[0024] In the process of the present invention, the above compounds can be reacted with the desired microelectronic device substrate in any suitable manner, such as in a single-wafer CVD, ALD and / or PECVD or PEALD chamber or in a furnace containing multiple wafers.

[0025] Alternatively, the process of the present invention may be performed as an ALD or similar ALD process. As used herein, the term "ALD or similar ALD" refers to processes such as: (i) sequentially introducing reactants (including silicon precursor (I) compounds and oxidation and / or reduction co-reactant gases) into a reactor (such as a single-wafer ALD reactor, a semi-batch ALD reactor, or a batch furnace ALD reactor), or (ii) exposing reactants (including silicon precursor (I) compounds and oxidation and / or reduction co-reactant gases) to the surface of a substrate or microelectronic device by moving or rotating the substrate to different sections of the reactor, with each section separated by an inert gas curtain, i.e., a space ALD reactor or a roll-to-roll ALD reactor.

[0026] Generally, the desired film prepared using precursor compounds of formula (I) can be customized by selecting the compounds and combining them with reduction or oxidation co-reactants. See, for example, the following reaction diagram 1, which illustrates how precursors of formula (I) can be used in a vapor deposition process: Reaction Diagram 1

[0027] In one embodiment, the vapor deposition process may further include a step involving exposing the precursor to a co-reactant gas (such as H2, H2 plasma, H2 / O2 mixture, water, N2O, N2O plasma, NH3, NH3 plasma, N2, or N2 plasma). For example, oxidizing co-reactant gases such as O2, O3, N2O, water vapor, alcohol, or oxygen plasma may be used. In one embodiment, the precursor BTCSE is used in an ALD process using O3 as the oxidizing co-reactant gas. In some embodiments, the gas further includes an inert gas, such as argon, helium, nitrogen, or combinations thereof. In another embodiment, the gas further includes nitrogen, which can react with the precursor of formula (I) under plasma conditions to form an oxynitride silicon film. In one embodiment, the invention relates to a high-temperature thermal atomic layer deposition (ALD) process using ozone as the oxidizing co-reactant gas to deposit a low-wet etch-rate silicon dioxide film.

[0028] In another embodiment, the above vapor deposition process may further include a step involving exposing the film to a co-reactant gas comprising a gas selected from H2, hydrazine (N2H4), methylhydrazine, tributylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and NH3. For example, ammonia may be used in a plasma-free deposition process to form silicon nitride. In some embodiments, the gas further comprises an inert gas, such as argon, helium, nitrogen, or combinations thereof.

[0029] In a preferred embodiment, the present invention relates to a high-temperature (e.g., above 400°C or above 600°C) thermal atomic layer deposition (ALD) process using ammonia as a reducing co-reactant gas to deposit silicon nitride films with low wet etch rates. Plasma-assisted or enhanced ALD processes typically provide films, such as silicon nitride films, with lower conformability and lower film thickness uniformity. Thermal ALD is therefore preferred, assuming that the deposition precursor is stable at elevated temperatures. Compounds of formula (I) have been found to be capable of both low-temperature PECVD and / or PEALD formation of silicon-containing films and high-temperature non-plasma ALD. Such compounds exhibit high volatility and chemical reactivity but are stable in terms of thermal degradation at temperatures involving the volatilization or evaporation of precursors, thereby allowing the resulting precursor vapor to be consistently and repeatedly delivered to the deposition zone or reaction chamber. In this regard, it has been surprisingly found that BTCSE is stable at temperatures exceeding 600°C, and furthermore, BTCSE only exhibits thermal degradation at approximately 650°C. The chemical reactivity of the compound of formula (I) allows for film growth using PEALD technology at low temperatures, where conventional silicon precursor materials (such as TEOS) are inert and therefore exhibit almost no deposition behavior. Furthermore, as described above, Figure 3 illustrates that the wet etching performance of the exemplary compound of formula (I) of the present invention (i.e., BTCSE) is significantly improved compared to the performance of the known silicon precursor BTBAS (bis(tert-butylamino)silane). Therefore, in another embodiment, the present invention provides the method of the present invention as described above, wherein the silicon-containing film is silicon dioxide, and wherein the silicon dioxide film thus formed exhibits a wet etching rate that is at least about 50% higher than that of SiO2 deposited with BTBAS and ozone.

[0030] Furthermore, it has been found that the chemical reactivity of the compound of formula (I) allows for film growth using thermal ALD technology at high temperatures, where conventional silicon precursors are generally unsuitable. As described above, Figure 6 illustrates that, for the formation of silicon nitride, the wet etching performance of the exemplary compound of formula (I) of the present invention (i.e., BTCSE) is significantly improved compared to the performance of the known silicon precursor HCDS (hexachlorodisilane). Therefore, in another embodiment, the present invention provides the method of the present invention as described above, wherein the silicon-containing film is silicon nitride, and wherein the silicon nitride film thus formed exhibits a wet etching rate that is at least about 50% higher than that of silicon nitride deposited with HCDS and ammonia. For example, the silicon nitride film can have a wet etching rate of less than 3.50 Å / min, such as less than 2.00 Å / min, at a film thickness of less than about 400 Å, such as less than about 250 Å.

[0031] When using a precursor compound of formula (I), carbon and nitrogen can be incorporated into such membranes by utilizing co-reactants (such as carbon in the form of, for example, methane, ethane, ethylene, or acetylene), thereby further introducing carbon inclusions into the silicon-containing membrane and producing silicon carbide. Similarly, nitrogen can be introduced by utilizing a nitrogen-containing reducing gas.

[0032] The deposition method disclosed herein may involve one or more purge gases. The purge gas system used to purify and remove unconsumed reactants and / or reaction byproducts is an inert gas that does not react with the precursors. Exemplary purge gases include, but are not limited to, argon, nitrogen, helium, neon, hydrogen, and mixtures thereof. In some embodiments, a purge gas (such as Ar) is supplied to the reactor at a flow rate in the range of about 10 to about 2000 sccm for about 0.1 to 1000 seconds, thereby purifying unreacted material and any byproducts that may remain in the reactor.

[0033] The respective steps of supplying the silicon precursor compound, co-reactant gas (such as oxidizing or reducing gas) and / or other precursors, source gas and / or reagents and / or changing the stoichiometric composition of the resulting dielectric film can be performed by changing the order of supplying the silicon precursor compound, co-reactant gas (such as oxidizing or reducing gas) and / or other precursors, source gas and / or reagents and / or changing the stoichiometric composition of the resulting dielectric film.

[0034] Energy is applied to at least one of a silicon precursor (I) compound and a co-reactant oxidizing gas, a reducing gas, or a combination thereof to initiate a reaction and form a silicon-containing film on a microelectronic device substrate. This energy can be provided by, but is not limited to, heat, pulsed heat, plasma, pulsed plasma, spiral plasma, high-density plasma, inductively coupled plasma, X-rays, electron beams (e-beams), photons, remote plasma methods, and combinations thereof. In some embodiments, a secondary RF frequency source can be used to modify the plasma characteristics at the substrate surface. In embodiments where plasma deposition is involved, the plasma generation process can include a direct plasma generation process where plasma is directly generated in a reactor, or alternatively, a remote plasma generation process, wherein the plasma is generated "remotely" in the reaction zone and on the substrate and supplied to the reactor.

[0035] As used herein, the term "microelectronic device" refers to a semiconductor substrate manufactured for use in microelectronic, integrated circuit, or computer chip applications, including 3D NAND structures, flat panel displays, and microelectromechanical systems (MEMS). It should be understood that the term "microelectronic device" is not intended to limit or include in any way any substrate including negative channel metal-oxide-semiconductor (nMOS) and / or positive channel metal-oxide-semiconductor (pMOS) transistors that will ultimately become a microelectronic device or microelectronic component. Such microelectronic devices incorporate at least one substrate, which may be selected from, for example, silicon, SiO2, Si3N4, OSG, FSG, silicon carbide, hydrogenated silicon carbide, silicon nitride, hydrogenated silicon nitride, silicon carbonitride, hydrogenated silicon carbonitride, boron nitride, antireflective coating, photoresist, germanium, germanium-containing, boron-containing, Ga / As, flexible substrate, porous inorganic material, metal (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). These films are compatible with a variety of subsequent processing steps, such as, for example, chemical mechanical planarization (CMP) and anisotropic etching processes.

[0036] Compounds of formula (I) can be prepared by reacting a substituted vinyl silane with a silane in the presence of tetra(triphenylphosphine)palladium (0). For example, the synthesis of compounds of formula (I) is illustrated in the following reaction diagram 2, wherein each R1 is hydrogen and each R2 is chlorine: Reaction diagram 2

[0037] The present invention can be further illustrated by the following examples of its preferred embodiments. It should be understood that these examples are included for illustrative purposes only and are not intended to limit the scope of the invention, unless otherwise expressly stated. Example 1 – Synthesis of BTCSE

[0038] Trichlorovinylsilane (500.0 g, 3.1 mol), trichlorosilane (419.4 g, 3.1 mol), and tetra(triphenylphosphine)palladium(O) (1.8 g) were placed in a 1 L 3-necked round-bottom flask. The reaction mixture was heated at 192 °C. After reaching 192 °C, the reaction mixture was cooled to 80 °C. The product was purified by simple distillation at 20 Torr at 80 °C to give a final product (825 g, 89.7%) as a colorless liquid. The product was found to be more than 98% pure. Example 2 – Vapor deposition using BTCSE and ozone as a co-reactant gas

[0039] Silicon oxide films were deposited using bis(trichlorosilyl)ethane (placed in a bubbler at 40°C). Using ozone reactants from 450°C to 650°C as the wafer temperature and controlling the reactor pressure at 0.5 to 1.5 Torr, a dual-cluster ALD reactor was used to deposit silicon oxide films on silicon wafers. Following silicon oxide deposition was a 21-second silicon pulse, a 20-second Ar purge, a 30-second ozone pulse, and a 20-second Ar purge; this cycle was repeated 190 times to obtain a film thickness of 300 Å. The film was saturated at 650°C for approximately 1.57 cycles and free of carbon and chlorine impurities. A wet etching rate of 62 Å / min was achieved using a 0.2% HF dilute solution. Example 3 – Vapor deposition using BTCSE with ammonia as a co-reactant gas.

[0040] Silicon nitride films were deposited using bis(trichlorosilyl)ethane (placed in a bubbler at 40°C). A dual-cluster ALD reactor was used to deposit silicon nitride films on silicon wafers, employing an ammonia reactant from 600°C to 725°C as the wafer temperature and controlling the reactor pressure at 0.5 to 1.5 Torr. Following silicon nitride deposition was a 21-second silicon pulse, a 20-second Ar purge, a 25-second ammonia pulse, and a 20-second Ar purge; this cycle was repeated 190 times to obtain a film thickness of 400 Å. The film was saturated at 725°C for approximately 1.45 cycles, with less than 10% carbon and no chlorine impurities. Using a 0.1% HF dilute solution, a wet etching rate of 1.7 Å / min was obtained. Example 4 – Vapor deposition using BTCSE with ammonia as a co-reactant gas.

[0041] Using a method similar to that described in Example 3, silicon oxycarbonitrile (SiOCN) films were deposited using bis(trichlorosilyl)ethane. SiOCN films were deposited on silicon sample blocks using ammonia co-reactants at 450°C and 515°C as sample block temperatures, with the reactor pressure controlled at 2 Torr. A 16-second ammonia pulse followed the silicon deposition, and these cycles were repeated to obtain film thicknesses of 150 to 200 Å. The growth rate was found to be 0.3 Å / cycle at 450°C and 0.23 Å / cycle at 515°C, as shown in Figure 9. The resulting film compositions are shown in Figures 10A and 10B.

[0042] Deposition was also performed on high aspect ratio structures. High conformability was found using the thermal ALD process utilizing BTCSE, as shown in Figure 11. Specifically, an 81% conformal silicon-containing film was formed on the AR11 trench structure at 450°C and a 97% conformal silicon-containing film was formed on the AR11 trench structure at 515°C.

[0043] Furthermore, the wet etching rate of the film was obtained using a 0.1% HF dilute solution. As shown in Figures 12A and 12B, the film formed at 450°C achieved an etching rate of 133 Å / min, and the film formed at 515°C achieved an etching rate of 188 Å / min.

[0044] The present invention has been described in detail with particular reference to certain embodiments thereof, but it should be understood that variations and modifications may be made within the spirit and scope of the present invention. [Simplified Explanation of the Diagram]

[0005] Figure 1 is a graph of growth rate (Å / cycle) versus precursor pulse time (in seconds). This graph compares the known silicon precursor BTBAS (bis(tert-butylamino)silane) using ozone as the oxidizing gas with the exemplary compound of formula (I) of the present invention (i.e., BTCSE) using ozone as the oxidizing gas.

[0006] Figure 2 illustrates the growth rate / cycle of the ALD silicon dioxide deposition process while the substrate temperature varies from 600°C to 650°C. Circular dots represent saturation curves and diamond dots represent refractive indices. In this experiment, an O3 flow rate of 1000 sccm was used. The pulse deposition cycle sequence used was (i) precursor 21 seconds, (ii) decontamination 20 seconds, (iii) ozone 30 seconds, and (iv) decontamination 20 seconds.

[0007] Figure 3 is a comparison of wet etching rates using thermal oxide as a normalized baseline = 1 (200:1 dilute HF). This figure illustrates that the wet etching performance of the exemplary compound of formula (I) of the present invention (i.e., BTCSE) is greatly improved compared to the known silicon precursor BTBAS (bis(tert-butylamino)silane).

[0008] Figure 4 shows the atomic percentage curve of the SiO2 film formed using BTCSE and ozone. This data indicates that there is no measurable amount of carbon or chlorine in the SiO2 film.

[0009] Figure 5 is a TEM (transmission electron microscopy) image of an exemplary microelectronic device structure, which illustrates the excellent SiO2 film formation in a high aspect ratio structure with a step coverage of more than 96%.

[0010] Figure 6 illustrates the growth rate / cycle of the thermal ALD silicon nitride deposition process while the substrate temperature varies from 600°C to 725°C. Square dots represent saturation curves and circular dots represent refractive indices. In this experiment, a flow rate of 300 sccm of NH3 was used. The pulse deposition cycle sequence used was (i) precursor 21 seconds, (ii) purge 20 seconds, (iii) ammonia 25 seconds, and (iv) purge 20 seconds.

[0011] Figure 7 shows a comparison of wet etching rates (100:1 dilute HF). This figure illustrates that, at a considerable thickness, the wet etching performance of silicon nitride prepared using the compound of exemplary formula (I) of this invention (i.e., BTCSE) is significantly improved compared to silicon nitride formed using the known silicon precursor HCDS (hexachlorodisilane). Silicon nitride prepared by CVD, as a reference example, exhibits an etching rate of 3.3 Å / min under the same conditions.

[0012] Figures 8A and 8B are atomic percentage curves of silicon nitride films formed by thermal deposition (non-plasma) of BTCSE and ammonia at 650°C and 725°C, respectively. This data shows that the silicon nitride films contain no measurable amounts of chlorine and very low levels of carbon, with even less carbon found at higher temperatures. This confirms that BTCSE can be used in high-temperature (above 600°C) non-plasma deposition processes to produce high-purity silicon nitride, which exhibits remarkably high etch resistance even at extremely low thicknesses.

[0013] Figure 9 illustrates the growth rate / cycle of thermal (non-plasma) ALD silicon deposition process using BTSCE and ammonia as a co-reactant at substrate temperatures of 450°C and 515°C. Figures 10A and 10B are atomic percentage curves of the resulting silicon-containing films, and Figure 11 confirms the extremely high conformability of these films when deposited on high aspect ratio structures. Figures 12A and 12B are wet etching rate results (100:1 dilute HF) of these thermal ALD films, using thermal oxides for comparison. All of these figures demonstrate that, using the compound of exemplary formula (I) of the present invention, the thermal ALD deposition process using ammonia as a co-reactant can provide highly conformable films at the desired growth rate and with good wet etching performance.

Claims

1. A method for forming a silicon-containing film on the surface of a microelectronic device, the method comprising introducing at least one compound of formula (I) into the surface in a reaction chamber at a temperature above 400°C under thermal atomic layer deposition conditions: (I), wherein each R1 is independently selected from hydrogen or C1-C4 alkyl, and each R2 is independently selected from chlorine, bromine, iodine, hydrogen or C1-C4 alkyl, with the limitation that not less than two R2 are selected from chlorine, bromine or iodine, wherein the silicon-containing film is silicon nitride, silicon oxynitride or silicon oxycarbonitride, and wherein the thermal atomic layer deposition conditions are non-plasma conditions, and the silicon-containing film contains about 9% to about 13% carbon and a silicon-nitrogen ratio of 1:

1.

2. The method of claim 1, wherein the thermal atomic layer deposition conditions are at a temperature above 400°C to about 600°C.

3. The method of claim 2, wherein the thermal atomic layer deposition conditions are at a temperature of about 425°C to about 525°C.

4. The method of claim 1, wherein the silicon-containing film has a thickness of about 100 Å to about 250 Å.

5. The method of claim 1, wherein the silicon-containing film is silicon oxycarbonitride.

6. The method of claim 1, wherein the compound of formula (I) has the following formula: .

7. The method of claim 1, wherein the compound of formula (I) has a purity greater than 98%.

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