Silicon carbide thin film and vapor deposition method thereof

Abstract

A vapor deposition process is provided for growing deposited hydrogen-free silicon carbide (SiC) and oxygen-containing SiC films (SiC:O). To prepare the SiC film, the method includes providing a silane precursor, such as TSCH (1,3,5-trisilacyclohexane), in a vapor phase with or without a diluent gas to a reaction zone containing a heated substrate, such that the precursor adsorbs and decomposes on the substrate surface without contact with any other reactive chemical species or co-reactants to form stoichiometric, hydrogen-free silicon carbide (SiC) having a 1:1 atomic ratio of silicon and carbon. For SiC:O films, an oxygen source is added to the reaction zone to dope the SiC film with oxygen. In the silane precursor, each carbon atom is bonded to two silicon atoms, and each silicon atom is also bonded to two or more hydrogen atoms.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 085,617, filed on September 30, 2020, the entire disclosure of which is incorporated herein by reference. Background of the Invention

[0004] Silicon carbide (SiC) thin films are gaining increasing research interest in a variety of applications. The appeal of SiC coatings is attributed to their highly desirable combination of physical, mechanical, electrical, and optoelectronic properties, making them a prime candidate for applications in the automotive, aerospace, computer chip, solar energy, lighting, and medical industries.

[0005] SiC coatings are used as hard protective coatings under challenging thermal, environmental and chemical conditions due to their high hardness (possibly exceeding 40 GPa), effective oxidation resistance, high temperature and thermal shock resistance, and chemical stability, as well as attractive mechanical, tribological and dielectric properties. Ultrathin SiC films have been widely used in integrated circuit (IC) technology, especially in microprocessor units (MPUs), system-on-a-chip (SoC), flash memory, and vertical stacking of electronic devices in so-called three-dimensional (3D) integrated systems. For example, SiC replaces silicon dioxide (SiO2) as a diffusion barrier layer in combination with low dielectric constant (κ) materials. Similarly, SiC is used as a capping layer and etch stop for copper interconnects.

[0006] In a similar manner, SiC thin films have been successfully incorporated into active optical devices and optoelectronic devices (including panel displays, lighting, and light-emitting devices) due to their wide bandgap (2.3 eV) and high electrical breakdown voltage. In this regard, SiC thin films are used as permeation barriers and encapsulation layers for light-emitting devices (LEDs) and organic LEDs (OLEDs), as well as in the manufacture of various planar optical systems and optical waveguides. In addition, SiC coatings have been suggested as passivation layers for flexible electroluminescent devices. The application of SiC has also expanded to the field of green energy, primarily in solar cells. For example, microcrystalline and amorphous SiC coatings are used as window layers for thin-film solar cells. As in the hard coating and computer chip industries, SiC thin films are used as passivation layers in silicon solar cells.

[0007] Despite extensive R&D efforts, significant challenges must be overcome to enable the expansion of SiC films into emerging industrial uses such as heterogeneous device applications. First, the majority of current SiC vapor deposition processes rely on the high-temperature reaction of silane-type or halide-type precursors (e.g., SiH4, Si2H6, and SiCl4) with C-containing precursors (e.g., CHCl3, C3H4, C2H2, and CCl4). The inherent challenges associated with the use of such chemistries are well documented and include their pyrophoric nature, a variety of environmental, health, and safety issues, the incorporation of high levels of hydrogen into the resulting SiC films, and the need for post-deposition annealing to achieve the desired SiC film specifications. The two parameters used to describe the quality of hydrogenated amorphous silicon carbide films are described in the empirical formula a-Si 1- x C 1+x :H, where x is related to the substitutional bonding of hydrogen atoms to silicon atoms, which prevents the stoichiometry of Si atoms to C atoms from being 1:1, and :H represents the doping (including possible interstitial) H atoms that do not change the stoichiometry of Si:C from 1:1. For high-quality silicon carbide, it is very desirable to have the lowest levels of both H-type defects.

[0008] Prior art efforts to address these challenges include plasma-assisted atomic layer deposition (PA-ALD) using TSCH (1,3,5-trisilacyclohexane) at 600°C, preferably between 100 and 200°C (U.S. Patent No. 8,440,571); the application of UV light treatment to selectively remove some precursor ligands and accessories to enable molecular layer deposition (U.S. Patent No. 8,753,985); and remote plasma processes to form plasma effluents that produce a flowable layer on the substrate (U.S. Patent Application Publication No. 2013 / 0217239). Unfortunately, all of these approaches fail to deposit a true stoichiometric SiC phase, instead producing films composed of arranged silicon-carbon-hydrogen networks with varying silicon-to-carbon ratios, varying hydrogen contents, and significant defect levels. Due to the significant impact of hydrogen on the physical, chemical, electrical, and optoelectronic properties of thin films, not only is its incorporation a practical concern, but the nature of Si-H bonds compared to C-H bonds also plays a significant role in tailoring the resulting film properties.

[0009] Another influencing factor is the Pauling relative electronegativity of the Si, C, and H elements (i.e., Si: 1.90; C: 2.55; H: 2.20). Si-C bonds have relatively high dipole moments, while Si-H bonds have relatively low dipole moments. Therefore, even if the atomic percentages of the film composition prepared using the known method are the same, the resulting film may have different atomic bonding arrangements, and the dielectric properties of the resulting film may also vary. In addition, the need for high-temperature annealing after deposition to remove H and reduce defect density increases complexity and cost, and limits the use of this known process for applications that do not require a thermally fragile substrate.

[0010] Other attempts to address these issues include the soft template approach (STA), which uses TSCH and a final material defined by self-assembly of a soluble directing agent (SDA) into a solvent; the SDA acts as a supramolecular template and the solvent functions as a SiC precursor. However, this process encounters a number of challenges that make it highly undesirable for semiconductor, optical, and optoelectronic applications. These challenges include: (i) the precursor pyrolysis is performed at very high temperatures (1000°C); (ii) the SDA medium requires a week to polymerize; (iii) the resulting SiC cannot be grown as a thin film, but rather exhibits a powder morphology of porous particles of stacked spherical particles; and (iv) the STA process is liquid-phase based on solvents, which is not conducive to integration into major manufacturing processes in the semiconductor, energy, optical, and optoelectronic industries.

[0011] For these reasons, it is desirable to provide a vapor deposition technique that overcomes the shortcomings of these and other known deposition techniques by forming high-quality, stoichiometric, minimally defective, and minimally added hydrogen-rich as-deposited SiC films while eliminating the problems associated with current silicon and carbon source precursors. It is further desirable that such a vapor deposition technique minimize the number and complexity of current processing conditions, thereby maximizing process safety, efficiency, and productivity. It is also desirable that such a vapor deposition technique control the SiC microstructure by varying processing parameters (e.g., substrate temperature and precursor flow rates) without requiring a subsequent annealing step to achieve crystallized SiC. Summary of the Invention

[0012] In one embodiment of the present invention, a method for preparing a deposited SiC film containing no more than 1 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber comprises:

[0013] providing a substrate in a reaction zone of a deposition chamber;

[0014] heating the substrate to a temperature of about 600° C. to about 1000° C.; and

[0015] providing a precursor comprising a silane in a gas phase free of a carrier gas to a reaction zone containing a substrate, wherein each carbon atom in the silane is bonded to two silicon atoms and each silicon atom is also bonded to two or more hydrogen atoms; and

[0016] wherein a SiC layer is formed on the surface of the substrate by adsorption and decomposition of the precursor;

[0017] Here, adsorption and decomposition occur on the substrate surface in the absence of any other reactive chemical species or co-reactants.

[0018] In another embodiment, the present invention provides a method of preparing a deposited SiC film containing no more than 0.2 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising:

[0019] providing a substrate in a reaction zone of a deposition chamber;

[0020] heating the substrate to a temperature of about 700° C. to about 1000° C.; and

[0021] providing a precursor comprising a silane in a gas phase free of a carrier gas to a reaction zone containing a substrate, wherein each carbon atom in the silane is bonded to two silicon atoms and each silicon atom is also bonded to two or more hydrogen atoms;

[0022] wherein a SiC layer is formed on the surface of the substrate by adsorption and decomposition of the precursor;

[0023] wherein the adsorption and decomposition occur on the substrate surface in the absence of any other reactive chemical species or co-reactants. In another embodiment, the present invention provides a method for preparing a deposited SiC:O film containing no more than 1 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising:

[0024] providing a substrate in a reaction zone of a deposition chamber;

[0025] heating the substrate to a temperature of about 600° C. to about 1000° C.;

[0026] providing a precursor comprising a silane in a gas phase free of a carrier gas to a reaction zone containing a substrate, wherein each carbon atom in the silane is bonded to two silicon atoms and each silicon atom is also bonded to two or more hydrogen atoms; and

[0027] concurrently providing a co-reactant reactive oxygen-containing gas to a reaction zone containing the substrate;

[0028] Wherein, a SiC:O layer is formed on the surface of the substrate through the adsorption and decomposition of the precursor.

[0029] In summary, the following embodiments are particularly preferably proposed within the scope of the present invention:

[0030] Embodiment 1: A method for preparing a deposited SiC film containing no more than 1 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising: providing a substrate in a reaction zone of a deposition chamber; heating the substrate to a temperature of about 600°C to about 1000°C; and providing a precursor comprising a silane hydrocarbon in a gas phase without a carrier gas to the reaction zone containing the substrate; wherein each carbon atom is bonded to two silicon atoms, and each silicon atom is also bonded to two or more hydrogen atoms; and wherein the SiC layer is formed on the surface of the substrate by adsorption and decomposition of the precursor; wherein the adsorption and decomposition occur on the surface of the substrate in the absence of any other reactive chemical species or co-reactants.

[0031] Embodiment 2: The method of the preceding embodiment, wherein the substrate comprises silicon, silicon oxide, silicon nitride, silicon carbide, gallium nitride, cobalt, ruthenium, copper, platinum, titanium, titanium nitride, tantalum, or tantalum nitride.

[0032] Embodiment 3: The method of any of the preceding embodiments, wherein the precursor comprises 1,3,5-trisilapentane; 1,3,5,7-tetrasilanonane; tricyclo[3.3.1.13,7]pentasilane; 1,3-disilacyclobutane; 1,3,5-trisilacyclohexane (TSCH); or 1,3,5,7-tetrasilacyclooctane.

[0033] Embodiment 4: The method of any one of the preceding embodiments, wherein the precursor comprises 1,3,5-trisilacyclohexane (TSCH) or 1,3,5,7-tetrasilacyclooctane.

[0034] Embodiment 5: The method of any preceding embodiment, wherein the SiC thin film has a Si:C atomic ratio of about 1:0.98 to 1:1.02.

[0035] Embodiment 6: The method according to any of the preceding embodiments, wherein the SiC film has a wavelength of 2080 cm-1 as measured by infrared spectroscopy. -1 The integrated area of ​​the Si-H bond peak at 730 cm-1 is consistent with that at 730 cm-1 measured by infrared spectroscopy. -1 The ratio of the integrated areas of the Si-C bond peaks at is less than about 1:50.

[0036] Embodiment 7: The method of any preceding embodiment, wherein the substrate is heated to a temperature of about 700°C to about 850°C.

[0037] Embodiment 8: A method for preparing a deposited SiC film containing no more than 0.2 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising: providing a substrate in the reaction zone of the deposition chamber; heating the substrate to a temperature of about 700°C to about 1000°C; and providing a precursor comprising a silane hydrocarbon in a carrier-free gas phase to the reaction zone containing the substrate, wherein each carbon atom is bonded to two silicon atoms and each silicon atom is also bonded to two or more hydrogen atoms; wherein a SiC layer is formed on the surface of the substrate by adsorption and decomposition of the precursor; wherein the adsorption and decomposition occur on the surface of the substrate in the absence of any other reactive chemical species or co-reactants.

[0038] Embodiment 9: The method of the preceding embodiment, wherein the substrate comprises silicon, silicon oxide, silicon nitride, silicon carbide, gallium nitride, cobalt, ruthenium, copper, platinum, titanium, titanium nitride, tantalum, or tantalum nitride.

[0039] Embodiment 10: The method of any of the preceding embodiments, wherein the precursor comprises 1,3,5-trisilapentane; 1,3,5,7-tetrasilanonane; tricyclo[3.3.1.13,7]pentasilane; 1,3-disilacyclobutane; 1,3,5-trisilacyclohexane (TSCH); or 1,3,5,7-tetrasilacyclooctane.

[0040] Embodiment 11: The method of any preceding embodiment, wherein the precursor comprises 1,3,5-trisilacyclohexane (TSCH) or 1,3,5,7-tetrasilacyclooctane.

[0041] Embodiment 12: The method of any preceding embodiment, wherein the SiC thin film has a Si:C atomic ratio of about 1:0.98 to 1:1.02.

[0042] Embodiment 13: The method of any of the preceding embodiments, wherein the SiC film has a wavelength of 2080 cm-1 as measured by infrared spectroscopy. -1 The integrated area of ​​the Si-H bond peak at 730 cm-1 is consistent with that at 730 cm-1 measured by infrared spectroscopy. -1 The ratio of the integrated areas of the Si-C bond peaks at is less than about 1:50.

[0043] Embodiment 14: The method of any preceding embodiment, wherein the substrate is heated to a temperature of about 700°C to about 850°C.

[0044] Embodiment 15: A method for preparing a deposited SiC:O film containing no more than 1 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising: providing a substrate in the reaction zone of the deposition chamber; heating the substrate to a temperature of about 600°C to about 1000°C; providing a precursor comprising a silicon hydrocarbon in a carrier-free gas phase to the reaction zone containing the substrate, wherein each carbon atom is bonded to two silicon atoms, and each silicon atom is also bonded to two or more hydrogen atoms; and simultaneously providing a co-reactant active oxygen-containing gas to the reaction zone containing the substrate; wherein the SiC:O layer is formed on the surface of the substrate by adsorption and decomposition of the precursor.

[0045] Embodiment 16: The method of the preceding embodiment, wherein the substrate comprises silicon, silicon oxide, silicon nitride, silicon carbide, gallium nitride, cobalt, ruthenium, copper, platinum, titanium, titanium nitride, tantalum, or tantalum nitride.

[0046] Embodiment 17: The method of any of the preceding embodiments, wherein the precursor comprises 1,3,5-trisilapentane; 1,3,5,7-tetrasilanonane; tricyclo[3.3.1.13,7]pentasilane; 1,3-disilacyclobutane; 1,3,5-trisilacyclohexane (TSCH); or 1,3,5,7-tetrasilacyclooctane.

[0047] Embodiment 18: The method of any preceding embodiment, wherein the precursor comprises 1,3,5-trisilacyclohexane (TSCH) or 1,3,5,7-tetrasilacyclooctane.

[0048] Embodiment 19: The method of any preceding embodiment, wherein the substrate is heated to a temperature of about 700°C to about 850°C.

[0049] Embodiment 20: The method of any of the preceding embodiments, wherein the oxygen-containing gas comprises oxygen, water, ozone, and / or nitrous oxide.

[0050] Brief Description of the Several Views of the Drawings

[0051] The following detailed description of the preferred embodiments of the present invention will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there are shown in the accompanying drawings embodiments that are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the accompanying drawings:

[0052] FIG1 is a representative XPS graph of Si and C concentration versus SiC penetration depth in SiC films deposited at 850° C., showing a Si:C atomic ratio ranging from 1:0.98 to 1:1.02 (nominally 1:1), according to one embodiment of the present invention;

[0053] FIG2 is a representative high-resolution XPS spectrum of Si2p binding energy in a SiC film deposited at 850° C., corresponding to a stoichiometric Si:C, according to an embodiment of the present invention;

[0054] 3 is a graph of FTIR absorption coefficient versus wave number for SiC deposited at 850° C. and annealed at 1000° C., in accordance with one embodiment of the present invention;

[0055] FIG4 is a graph showing the FWHM of SiC at the FTIR peak as a function of deposition temperature according to one embodiment of the present invention;

[0056] FIG5 depicts the FTIR normalized absorption coefficient of a deposited SiC film using TSCH as a Si precursor according to an embodiment of the present invention compared to a post-annealed SiC film deposited using a baseline (control) Si source precursor;

[0057] FIG6 depicts photoluminescence (PL) measurements of a deposited SiC film using TSCH as a Si precursor according to an embodiment of the present invention, compared to a SiC film deposited using a benchmark (control) Si source precursor;

[0058] FIG7 depicts the FWHM and peak position of the SiC FTIR peak of SiC materials according to one embodiment of the present invention and a TMDSB control as a function of substrate temperature;

[0059] 8 is a graph showing the growth rate of a SiC film as a function of deposition temperature at 0.2 Torr according to one embodiment of the present invention;

[0060] FIG9 plots the refractive index (n) and absorption coefficient (a) values ​​of a SiC film at a wavelength of 500 nm as a function of substrate temperature, as measured by ellipsometry, according to an embodiment of the present invention;

[0061] 10 is a graph of the absorption coefficient of SiC grown by TSCH at 650° C. compared to a control (TMDSB) SiC sample, in accordance with one embodiment of the present invention;

[0062] FIG11( a ) shows FTIR spectra of SiC samples deposited at three different deposition temperatures (650° C., 700° C., and 800° C.) in accordance with an embodiment of the present invention, with an extended wavenumber range from 500 to 3000 cm -1 ;and

[0063] Figure 11(b) is a graph of Figure 11(a) at approximately 2090 cm -1 A magnified view of the absorption peak, which corresponds to the Si-H stretching mode, to better understand the size of the Si-H peak.

[0064] Detailed description of the invention

[0065] The present invention relates to a vapor deposition method for producing crystalline and amorphous deposited silicon carbide (SiC) films and SiC films including oxygen (SiC:O films) having extremely low concentrations of structural and compositional defects, particularly defects associated with variations from the ideal stoichiometry of silicon carbide (Si:C=1:1) and substitutional and interstitial defects associated with the presence of hydrogen, and films produced by such processes. It is generally recognized in the art that silicon carbide films having a hydrogen content of 10 atomic % or less are considered to exhibit "low hydrogen incorporation," and films having a hydrogen content of 1 atomic % or less are considered to be "hydrogen-free" (see, for example, A. Kleinowaé et al., "FTIR Spectra of Silicon Carbide Thin Films Prepared Using PECVD for Solar Cell Applications," Proc., SPIE9563, Reliability of Photovoltaic Cells, Modules, Assemblies and Systems VIII, 95630U (September 2015); S. Gallis et al. “Photoluminescence of Erbium-doped Amorphous Silicon Carbide Thin Films at 1540 nm,” J. Mater. Res., 19(8), 2389-2893, 2004).

[0066] The methods described herein can be used to produce SiC films with low hydrogen incorporation and hydrogen-free SiC films, as defined above, as well as SiC:O films. Consistent with current terminology in the art, a film containing "low hydrogen content" means that the film contains 10 atomic % or less of hydrogen, "hydrogen-free" means that the film contains 1 atomic % or less of hydrogen, and a film containing "undetectable" hydrogen contains 0.2 atomic % or less of hydrogen. For the purposes of the present invention, a silicon carbide film with undetectable hydrogen can also be understood to mean that the film has a hydrogen content below the detection limit of spectroscopic methods and equipment, such as infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS), which is estimated to be equal to or less than 0.2 atomic %.

[0067] The term "thin film" is well known in the art and can include films with thicknesses ranging from a few nanometers to several micrometers. More specifically, the term "thin film" can be understood as a film having a thickness less than 500 nanometers, and preferably between 2 and 50 nm. In the art, the phrase "as-deposited" is understood to mean that the film is ready for use after deposition without further processing (such as plasma processing, irradiation, or thermal annealing).

[0068] To prepare SiC thin films, the method according to the present invention comprises providing a silane precursor as described below, preferably TSCH (1,3,5-trisilacyclohexane), in a gas phase (with or without a carrier gas or diluent gas) to a reaction zone containing a heated substrate, thereby causing the precursor to adsorb and decompose, thereby forming stoichiometric silicon carbide (SiC) on the substrate surface with a Si:C atomic ratio of 1:0.98 to 1:1.02 (nominally 1:1) without additional contact with any other reactive chemical species or co-reactants. To form a SiC:O film, an oxygen source is added to the reaction zone to adjust the doping. Alternatively, the deposited SiC film can be subsequently reacted with or treated with an oxygen source. The grain size and morphology of the SiC and SiC:O films can be adjusted by controlling process parameters (such as substrate temperature and precursor flow rate), and crystalline films can be achieved without a subsequent annealing step. However, annealing can also be performed if larger grains or epitaxial phases are desired.

[0069] The vapor deposition technology described herein overcomes the shortcomings of known deposition technologies and is capable of growing high-quality, stoichiometric deposited SiC films with 1% or less defects and / or hydrogen without the need for post-deposition annealing. It also eliminates the problems associated with current Si and C source precursors, minimizing the number and complexity of current process conditions, thereby maximizing process safety, efficiency, and productivity.

[0070] The resulting SiC thin films will be highly beneficial for key applications in the semiconductor, energy, optical, and optoelectronics industries. In particular, the presence of minimal defects and hydrogen in the deposited SiC films makes them well-suited for applications in optical and photoluminescent devices, where the inclusion of defects and hydrogen in deposited SiC often hinders optical and photoluminescent performance and requires high-temperature annealing to correct these defects. In contrast, the presence of minimal defects and hydrogen in the deposited SiC films described herein enables fine-tuning of dopant concentrations (e.g., oxygen and erbium) and optical properties, maximizing the optical and photoluminescent performance of the resulting devices and systems.

[0071] The method according to the present invention utilizes a class of source precursors containing silicon and carbon, carbosilanes, or silanes, wherein each carbon atom in the silane is bonded to two silicon atoms, and each silicon atom is also bonded to two or more hydrogen atoms. The ratio of silicon atoms to carbon atoms in the precursor is preferably in the range of about 1 to 1.5. Exemplary precursors include 1,3,5,7-tetrasilanonane; 1,3,5,7-tetrasilacyclooctane; tricyclo[3.3.1.13,7]pentasilane; and 1,3-disilacyclobutane (not readily available), and preferred commercial precursors include 1,3,5-trisilapentane and 1,3-trisilacyclohexane (TSCH); most preferred is the commercially available cyclic carbosilane 1,3,5-trisilacyclohexane (TSCH). Unlike silane-type or halide-type silicon precursors (e.g., SiH4, Si2H6, and SiCl4), this type of Si precursor contains both silicon atoms and carbon atoms, thereby providing a decomposition pathway for forming stoichiometric SiC without the need for carbon-containing co-reactants. The chemical structure and bonding configuration of silane-type precursors (e.g., TSCH) enable decomposition to produce stoichiometric SiC at lower temperatures than the temperatures required for the reaction of silane-type or halide-type precursors (e.g., SiH4, Si2H6, and SiCl4) with carbon-containing precursors (e.g., CHCl3, C3H4, C2H2, and CCl4), and without the need for a post-deposition annealing step.

[0072] Suitable substrates include silicon, which is preferred, and materials such as, but not limited to, silicon oxide, silicon nitride, silicon carbide, gallium nitride, cobalt, ruthenium, copper, platinum, titanium, titanium nitride, tantalum, tantalum nitride, and many substrates used for optics and photoluminescence.

[0073] An important aspect of the vapor deposition technique described herein is that the method is based on strictly controlled experimental conditions, including source precursor temperature, substrate temperature, precursor flow rate, precursor partial pressure in the reaction zone, and total reaction pressure, to ensure that the source precursor decomposition pathway occurs in a surface reaction-limited regime rather than a mass transport-limited regime. These parameters ensure strict control of the adsorption and decomposition mechanisms of the silane-based precursors to optimize the energy of ligand removal and hydrogen elimination while maintaining the integrity of the Si-C bond to obtain a 1:1 Si:C ratio in the resulting film.

[0074] In this surface reaction-limited regime, while not wishing to be bound by theory, the methods described herein ensure that two key processes occur: (i) an elimination reaction to form a Si-C double bond structure, "silicene," followed by (ii) dissociative adsorption of hydrogen from silicon atoms, which results in SiC films that can be described as having low hydrogen content (<10 atomic % hydrogen), no hydrogen (less than 1 atomic % hydrogen), or having undetectable hydrogen content (<0.2 atomic % hydrogen), depending on the deposition parameters, particularly substrate temperature. Furthermore, regardless of substrate deposition temperature, the resulting SiC films consist solely of simply cross-linked Si-C bonds, with variations of less than 0.2% from a 1:1 Si:C stoichiometry (which can be expressed as a range of 1:0.98 to 1:1.02). These films are in stark contrast to prior art films, in which the SiC matrix exhibits a shift from predominantly C-Si to C-C, C-Si, and C-H type bonds, while silicon evolves from Si-C bonds to Si-C, Si-Si, and Si-H bonds as a function of process conditions. This results in a variety of complex, temperature-dependent bonding configurations in the SiC films, including high defect density and significant hydrogen content.

[0075] "Low hydrogen content" may also be understood to refer to a material that has a low hydrogen content as measured by infrared spectroscopy at 2080 cm-1 using standard spectroscopy techniques. -1 The integrated area of ​​the Si-H bond peak at 730 cm -1 The ratio of the integrated area of ​​the Si-C bond peak at 1.75 eV to the integrated area of ​​the Si-H bond peak at 1.75 eV is less than 1:50. "Low hydrogen content" can be further understood to refer to materials with a ratio of Si-H bond density to Si-C bond density of less than 1:50 as measured by infrared spectroscopy. It should be noted that the ratio of these IR absorption peaks is only a correlation, indicating a very low content of Si-H bonds below the IR detection limit. Alternatively, spectroscopic ellipsometry can be used to observe that undoped SiC in the visible region has a peak density of less than 10 3 cm -1 Low levels of hydrogen incorporation (and other defects as described above) can be determined by the absorption coefficient of

[0076] In a preferred embodiment, films with a 1:1 Si:C stoichiometry and undetectable hydrogen (less than 0.2 atomic %) can be prepared at substrate deposition temperatures greater than about 700°C and less than about 1000°C. In other embodiments where higher levels of hydrogen can be tolerated but a 1:1 Si:C stoichiometry is still required, the process temperature is in the range of about 600°C to about 700°C, which is advantageous both in terms of reducing device exposure to thermal damage and energy efficiency. For example, at a deposition temperature of 650°C, the hydrogen content of the film can be detected, estimated to be at a level of 0.2-1.0 atomic %, while the stoichiometry of the film remains unchanged. It should be noted that the above ranges are intended to include all temperatures within these ranges, such as, but not limited to, 600°C, 625°C, 650°C, 675°C, 700°C, 725°C, 750°C, 775°C, 800°C, 825°C, 850°C, 875°C, 900°C, 925°C, 950°C, 975°C, and 1000°C. Preferably the substrate deposition temperature is from about 700°C to about 850°C, such as 700°C, 725°C, 750°C, 775°C, 800°C, 825°C and 850°C.

[0077] In one embodiment, aspects of the present invention relate to a method for producing a deposited crystalline SiC film that is free of hydrogen (no more than 1 atomic % hydrogen), the method comprising providing a silane-based precursor as described above, such as preferably TSCH, in a vapor phase (without a carrier gas) to a reaction zone of a deposition chamber containing a heated substrate as described above, the temperature of the heated substrate being from about 600° C. to about 1000° C. (preferably from about 700° C. to about 1000° C.) such that adsorption and decomposition of the TSCH or other precursor occurs on the substrate surface, such that a SiC layer is formed on the substrate in the absence of any other reactive chemical species or co-reactants. The decomposition process produces a deposited hydrogen-free crystalline SiC film without the need for a post-deposition annealing step. It is also within the scope of the present invention to provide the precursor in a vapor phase containing a dilute inert non-reactive gas, as this may provide practical advantages or conveniences, but a diluent gas is not required.

[0078] The source temperature of the TSCH or other precursor is maintained at about −25° C. to about 75° C., more preferably at about 0° C. to about 25° C., and the partial vapor pressure of the precursor in the deposition chamber is maintained at about 10% to about 100% of the total pressure in the reaction zone, more preferably at about 50% to about 90% of the total pressure in the reaction zone; if a diluent gas is present, the remainder of the partial pressure comes from the diluent gas. If no diluent gas is present, the vapor pressure of the precursor is the total pressure of the system, as the precursor vapor pressure alone maintains the total pressure (vacuum) in the system, thus eliminating the need for a diluent or carrier gas. The substrate deposition temperature is maintained at about 600° C. to about 1000° C., more preferably at about 700° C. to about 850° C. The total pressure in the reaction zone (deposition chamber), also known as the operating pressure, is maintained at about 0.1 Torr to about 760 Torr, more preferably at 0.2 Torr to 10 Torr. In addition, the diluent gas flow rate (if used) is maintained at about 10 to about 1000 sccm, more preferably at 50 to 250 sccm.

[0079] If a diluent gas is used, it is selected from the group of known inert gases such as helium, neon, argon and xenon.

[0080] These process parameters are used to form SiC films, ensuring that the Si:C stoichiometry measured by XPS is 1:1±0.05, preferably 1:1±0.02 (1:1.098 to 1:1.02), and the hydrogen measured by infrared spectroscopy is less than 1 atomic %. In addition, the SiC film measured by infrared spectroscopy has a carbon stoichiometry of 1:1±0.05, preferably 1:1±0.02 (1:1.098 to 1:1.02), and the hydrogen stoichiometry measured by infrared spectroscopy is less than 1 atomic %. -1 The integrated area of ​​the Si-H bond peak at 730 cm -1 The ratio of the integrated areas of the Si-C bond peaks at is less than about 1:50.

[0081] In another embodiment, aspects of the present invention relate to a method for producing a deposited crystalline SiC film having an undetectable concentration (no more than 0.2 atomic %) of H (interstitial and substitutional) and defects. The method comprises providing a TSCH or other silane-based precursor as described above in a vapor phase to a reaction zone of a deposition chamber containing a heated substrate as described above at a temperature of about 700°C to about 1000°C (preferably about 700°C to about 850°C) such that adsorption and decomposition of the TSCH or other precursor occurs on the substrate surface in the presence of a diluent inert non-reactive gas, thereby forming a SiC layer on the substrate without the intervention of any other reactive chemical species or co-reactants. The decomposition process produces a deposited crystalline SiC film having undetectable H (interstitial and substitutional) and defects as described above without the need for a post-deposition annealing step. Providing a vapor phase precursor containing a diluent inert non-reactive gas is also within the scope of the present invention as it can provide practical advantages or conveniences, but the diluent gas is not required.

[0082] The source temperature of the TSCH or other precursor is maintained at about -25 to about 75°C, more preferably at about 0 to about 25°C, and the partial vapor pressure of the precursor in the deposition chamber is maintained at about 10% to about 100% of the total pressure in the reaction zone, more preferably at about 50% to about 90% of the total pressure in the reaction zone; the remaining partial pressure comes from the diluent gas (if present). If there is no diluent gas, the vapor pressure of the precursor is the total pressure of the system, because the precursor vapor pressure alone maintains the total pressure (vacuum) in the system, and therefore no diluent or carrier gas is required. The substrate deposition temperature is maintained at about 700°C to about 1000°C, more preferably at about 700 to about 850°C. The total pressure in the reaction zone (deposition chamber), also known as the operating pressure, is maintained at about 0.1 Torr to about 760 Torr, more preferably 0.2 Torr to 10 Torr. In addition, the flow rate of the diluent gas (if used) is maintained at about 10 to about 1000 sccm, more preferably 50 to 250 sccm.

[0083] If a diluent gas is used, it is selected from the group of known inert gases such as helium, neon, argon and xenon.

[0084] These process parameters are used to form SiC films, ensuring that the stoichiometry of Si:C is 1:1±0.05, preferably 1:1±0.02 (1:1.098 to 1:1.02), and has less than 1 atomic % hydrogen. In addition, the SiC film measured by infrared spectroscopy has a carbon content of 0.0447 W / cm2 at 2080 nm. -1 The integrated area of ​​the Si-H bond peak at 730 cm -1 The ratio of the integrated areas of the Si-C bond peaks at is less than about 1:50.

[0085] In another embodiment, aspects of the present invention relate to a method for preparing a deposited SiC:O film containing no more than 1 atomic % hydrogen. The method comprises providing TSCH (or other precursor as defined above) in a gas phase (without a carrier gas or diluent gas) to a reaction zone of a deposition chamber containing a heated substrate, wherein the temperature of the substrate is from about 600°C to about 1000°C (preferably from about 700°C to about 850°C), as described above, and simultaneously introducing an oxygen-containing gas into the reaction zone of the deposition chamber so that adsorption and decomposition of TSCH occur on the surface of the substrate in the presence of the reactive oxygen-containing gas as a co-reactant, thereby forming a SiC:O layer on the surface of the substrate. It is also within the scope of the present invention to provide a precursor in a gas phase containing a diluent inert non-reactive gas, as this can provide practical advantages or convenience, but a diluent gas is not required. The decomposition process produces a deposited hydrogen-free SiC:O film, i.e., a film containing no more than 1 atomic % hydrogen.

[0086] The source temperature of TSCH or other precursors is maintained at about -25 to about 75°C, more preferably at about 0 to about 25°C, and the TSCH partial vapor pressure in the deposition chamber is maintained at about 10% to about 100% of the total pressure in the reaction zone, more preferably at about 50% to about 90% of the total pressure in the reaction zone. The flow rate of the oxygen-containing gas co-reactant is set so that the corresponding vapor partial pressure in the reaction zone reaches about 1% to about 25% of the vapor partial pressure of the carbosilane precursor, more preferably about 5% to about 10% of the carbosilane precursor. The substrate deposition temperature is maintained at about 600°C to about 1000°C, more preferably about 700 to about 850°C. The total pressure in the reaction zone (deposition chamber), also known as the working pressure, is maintained at about 0.1 Torr to about 760 Torr, more preferably 0.2 Torr to 10 Torr. In addition, the dilution gas flow rate (if used) is maintained at about 10 to about 1000 sccm, more preferably 50 to 250 sccm.

[0087] If a diluent gas is used, it is selected from known inert gases such as helium, neon, argon and xenon. The oxygen-containing gas co-reactant is selected from oxygen, water, ozone, nitrous oxide and other typical oxygen-containing reactants known in the art.

[0088] Alternatively, the deposited SiC films can be subsequently treated in situ (before removal from the deposition chamber) or ex situ (removing them from the deposition chamber and placing them in a furnace or annealing chamber) by contacting with an oxygen-containing source to form SiC:O films.

[0089] It is also within the scope of the present invention to replace some or all of the hydrogen atoms bonded to silicon atoms in the precursor with deuterium atoms. Since deuterium is less likely than hydrogen to cause hydrogen-related dislocations in amorphous silicon and silicon carbide, this can advantageously eliminate the dislocations associated with the 2000-2260 cm -1 Substitutional defects associated with infrared absorption of Si-H bonds within the range of 100 nm can even further reduce the overall concentration of interstitial defects (if any exist). In the case of trisilacyclohexane, all six hydrogen atoms are replaced by deuterium atoms. This compound can be easily prepared by reducing the hexaalkoxytrisilacyclohexane intermediate with deuterated lithium aluminum. As another example, the eight hydrogen atoms bonded to silicon in trisilapentane can be replaced with deuterium in a similar manner.

[0090] The invention will now be described with reference to the following non-limiting examples.These examples describe the deposition of stoichiometric SiC films containing very low levels of defects and hydrogen from TSCH (trisilacyclohexane) on Si substrates.

[0091] Example 1: Determining the optimized process window

[0092] Six stoichiometric SiC films were prepared by decomposing TSCH (1,3,5-trisilacyclohexane) on Si substrates using the process parameters summarized in Table I.

[0093] Table I. Process parameters for producing SiC using TSCH as a source precursor

[0094]

[0095] The obtained films were analyzed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) measurements.

[0096] As shown in Figures 1 and 2, XPS depth profiling was used to evaluate the Si and C concentrations in the SiC films versus penetration depth for deposited SiC films grown on substrates at 850°C. Similar data were obtained for Runs 2, 3, and 6, demonstrating the robustness of the deposition process. The data showed a consistent 1:1 Si:C atomic ratio throughout the film, with an accuracy of 1:0.98 to 1:1.02, indicating that the film was stoichiometric. Figure 8 shows high-resolution XPS spectra of the Si2p binding energy for SiC films deposited at 800°C; Runs 1 and 5 (of varying film thicknesses) yielded identical X-ray photoelectron spectroscopy (XPS) spectra. The Si2p binding energy position at 100.3 eV confirms that the chemical bond is Si-C (standard: 3C-SiC).

[0097] FTIR analysis showed the following: (i) As shown in Figure 3, at 800 cm -1 A single strong absorption peak was observed near the Si-C stretching mode in crystalline SiC. After annealing at 1000 °C for 1 h, the FWHM of the FTIR peak decreased from 62.0 to 49.8 cm -1 , indicating that the crystallinity increases due to annealing. (ii) As shown in Figure 4, the FWHM of the FTIR peak decreases with increasing deposition temperature, indicating that the deposited crystallinity increases with increasing deposition temperature.

[0098] Example 2: Study of process parameters and precursor chemistry

[0099] Ten stoichiometric SiC films of the present invention were prepared by decomposing TSCH (1,3,5-trisilacyclohexane) on Si substrates, and two comparative SiC films (Runs 7 and 14) were prepared by decomposing TMDSB (1,1,3,3-tetramethyl-1,3-disilacyclobutane) as a precursor on Si substrates. The process parameters are summarized in Table II below.

[0100] Table II Process parameters for producing SiC films of the present invention and comparative SiC films

[0101]

[0102]

[0103] *(1,1,3,3-Tetramethyl-1,3-disilacyclobutane)

[0104] Figure 5 shows a comparison of the crystallinity between a SiC film deposited using a reference precursor and then annealed, as a control, and a SiC film deposited using TSCH as a precursor. FTIR spectroscopy shows that the SiC film deposited using the TSCH precursor exhibits 100% the same crystallinity as the SiC film deposited from the reference Si source precursor after annealing at 1100°C. It is noteworthy that the reference precursor TMDSB does not deposit below 800°C, and the SiC deposited from the reference material contains a large amount of H (over 11 at%) and defects.

[0105] Photoluminescence (PL) measurements for SiC films deposited using a benchmark TMDSB control precursor and for SiC films using TSCH as a precursor are shown in Figure 6. As can be seen, the SiC film using TSCH as a precursor exhibits negligible PL intensity, indicating a significant reduction in defect density compared to the SiC film deposited using the benchmark (TMDSB) Si source precursor.

[0106] Figure 7 is a graph showing the peak position and FWHM of the SiC FTIR peak for the TMDSB control and the TSCH samples of the present invention as a function of substrate temperature. As substrate temperature increases, the FWHM decreases and the peak position red-shifts, indicating higher crystallinity at higher deposition temperatures.

[0107] In addition, the growth rate as a function of deposition temperature at 0.2 Torr is shown in Figure 8. The highest growth rate of 2.23 nm / s was observed at 850° C. As expected, the growth rate decreases with decreasing substrate temperature due to the reduction in thermal energy available for the precursor decomposition reaction.

[0108] Representative atomic force microscopy (AFM) micrographs of SiC samples were measured as a function of substrate temperature (not shown). The root mean square (rms) value of the surface roughness increased with increasing substrate temperature. This result is expected, as the crystallinity increases with increasing substrate temperature.

[0109] Scanning electron microscopy (SEM) results (not shown) for substrate temperatures of 800°C, 700°C, and 650°C show good correlation with the AFM data in terms of surface roughness root mean square, with the surface roughness increasing with increasing substrate temperature.

[0110] Figure 9 plots the refractive index (n) and absorption coefficient (a) values ​​of the SiC films at a wavelength of 500 nm, as measured by ellipsometry, as a function of deposition temperature; n values ​​are represented by circles, and a values ​​by triangles. For all deposition temperatures, the refractive index n varies between 2.9 and 2.7, which is consistent with the reference value of 3C-SiC (2.7), indicating the presence of a stoichiometric SiC phase.

[0111] Furthermore, a comparison of the absorption coefficient of SiC grown by TSCH at 650°C compared to a control TMDSB SiC sample is shown in Figure 10. The absorption of the TSCH SiC film drops sharply in the visible range, in stark contrast to the control SiC sample, which exhibits high absorption across the entire energy range. This clearly indicates that the defect density of the SiC grown at 650°C is significantly lower than that of the control SiC sample.

[0112] Finally, Figure 11(a) depicts the FTIR spectra of SiC samples of the present invention deposited at three different temperatures (650°C, 700°C, and 800°C) in the extended wavenumber range from 500 to 3000 cm -1 The FTIR spectrum shows the following: (i) 800 cm -1 A single high-intensity absorption peak near 2090 cm-1 for the sample grown at 650 °C corresponds to the Si-C stretching mode in crystalline SiC; and (ii) a peak at 2090 cm-1 for the sample grown at 650 °C. -1 The smallest absorption peak near 2090 cm corresponds to the Si-H stretching mode. For samples deposited at 700℃ and 800℃, the Si-H peak signal decreases below the background signal, indicating that the H in the SiC sample is below the detection limit of FTIR. Figure 11(b) is the peak at 2090 cm corresponding to the Si-H stretching mode. -1 Zoomed-in views of nearby absorption peaks to better understand the Si-H peak size.

[0113] It will be appreciated by those skilled in the art that changes may be made to the embodiments described above without departing from the broad inventive concept thereof.

Claims

1. A method for preparing a deposited SiC film containing no more than 1 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising: providing a substrate in a reaction zone of a deposition chamber; heating the substrate to a temperature of 700° C. to 850° C.; and Providing a precursor comprising a silane hydrocarbon in a gas phase without a carrier gas to a reaction zone containing a substrate at a temperature of 700° C. to 850° C., the precursor comprising 1,3,5,7-tetrasilanonane, tricyclo[3,3,1,13,7]pentasilane, 1,3-disilacyclobutane, 1,3,5-trisilacyclohexane (TSCH), or 1,3,5,7-tetrasilacyclooctane; wherein the partial pressure of the precursor in the deposition chamber is maintained at 10% to 100% of the total pressure of the reaction zone; and wherein a SiC layer is formed on the surface of the substrate by adsorption and decomposition of the precursor; Here, adsorption and decomposition occur on the substrate surface in the absence of any other reactive chemical species or co-reactants.

2. The method of claim 1, wherein the substrate comprises silicon, silicon oxide, silicon nitride, silicon carbide, gallium nitride, cobalt, ruthenium, copper, platinum, titanium, titanium nitride, tantalum, or tantalum nitride.

3. The method of claim 1, wherein the precursor comprises 1,3,5-trisilacyclohexane (TSCH) or 1,3,5,7-tetrasilacyclooctane. The method according to claim 1 , wherein the SiC thin film has a Si:C atomic ratio of 1:0.98 to 1:1.

02.

5. The method according to claim 1, wherein The SiC film measured by infrared spectroscopy has a wavelength of 2080 cm -1 The integrated area of ​​the Si-H bond peak at 730 cm -1 The ratio of the integrated areas of the Si-C bond peaks at is less than 1:

50.

6. A method for preparing a deposited SiC film containing no more than 0.2 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising: providing a substrate in a reaction zone of a deposition chamber; heating the substrate to a temperature of 700° C. to 850° C.; and Providing a precursor comprising a silane hydrocarbon in a gas phase without a carrier gas to a reaction zone containing a substrate at a temperature of 700° C. to 850° C., the precursor comprising 1,3,5,7-tetrasilanonane, tricyclo[3.3.1.13,7]pentasilane, 1,3-disilacyclobutane, 1,3,5-trisilacyclohexane (TSCH), and 1,3,5,7-tetrasilacyclooctane; wherein the partial pressure of the precursor in the deposition chamber is maintained at 10% to 100% of the total pressure of the reaction zone; wherein a SiC layer is formed on the surface of the substrate by adsorption and decomposition of the precursor; Here, adsorption and decomposition occur on the substrate surface in the absence of any other reactive chemical species or co-reactants.

7. The method of claim 6, wherein the substrate comprises silicon, silicon oxide, silicon nitride, silicon carbide, gallium nitride, cobalt, ruthenium, copper, platinum, titanium, titanium nitride, tantalum, or tantalum nitride.

8. The method of claim 6, wherein the precursor comprises 1,3,5-trisilacyclohexane (TSCH) or 1,3,5,7-tetrasilacyclooctane. 9 . The method according to claim 6 , wherein the SiC thin film has a Si:C atomic ratio of 1:0.98 to 1:1.

02.

10. The method according to claim 6, wherein: The SiC film measured by infrared spectroscopy has a wavelength of 2080 cm -1 The integrated area of ​​the Si-H bond peak at 730 cm -1 The ratio of the integrated areas of the Si-C bond peaks at is less than 1:

50.

11. A method for preparing a deposited SiC:O film containing no more than 1 atomic % hydrogen on a substrate in a reaction zone of a deposition chamber, the method comprising: providing a substrate in a reaction zone of a deposition chamber; heating the substrate to a temperature of 700° C. to 850° C.; Providing a precursor comprising a silane hydrocarbon in a gas phase without a carrier gas to a reaction zone containing a substrate at a temperature of 700° C. to 850° C., the precursor comprising 1,3,5,7-tetrasilanonane, tricyclo[3.3.1.13,7]pentasilane, 1,3-disilacyclobutane, 1,3,5-trisilacyclohexane (TSCH), and 1,3,5,7-tetrasilacyclooctane; wherein the partial pressure of the precursor in the deposition chamber is maintained at 10% to 100% of the total pressure of the reaction zone; and Simultaneously providing a co-reactant reactive oxygen-containing gas to a reaction zone containing the substrate; A SiC:O layer is formed on the surface of the substrate by adsorption and decomposition of the precursor.

12. The method of claim 11, wherein the substrate comprises silicon, silicon oxide, silicon nitride, silicon carbide, gallium nitride, cobalt, ruthenium, copper, platinum, titanium, titanium nitride, tantalum, or tantalum nitride.

13. The method of claim 11, wherein the precursor comprises 1,3,5-trisilacyclohexane (TSCH) or 1,3,5,7-tetrasilacyclooctane.

14. The method of claim 11, wherein the oxygen-containing gas comprises oxygen, water, ozone and / or nitrous oxide.

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