Silicon-based thin films prepared from n-alkyl substituted perhydridocyclotrisilazanes

Abstract

A low to moderate temperature vapor deposition process is provided for depositing silicon-based thin films, such as silicon nitride films, silicon carbon nitride films, silicon oxide films, and silicon films. The process includes heating a substrate to a predetermined temperature in a single cycle, providing a precursor containing a gas phase N-alkyl substituted perhydridocyclotrisilazane to a reaction zone containing the substrate to form a monolayer of the precursor by adsorption to the substrate surface, and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a co-reactant. The adsorbed precursor monolayer reacts with the soft plasma and is converted to a discrete atomic or molecular layer of the silicon-based thin film by dissociation and / or decomposition induced by or from the substrate surface. The cycle is then repeated to form the silicon-based thin film to a desired thickness.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 030,684, filed May 27, 2020, the disclosure of which is incorporated herein by reference. Background Technology

[0003] Focus on silicon-based thin films such as (SiN) x The research, development, and fabrication of silicon dioxide (SiO2) are at an unprecedented pace, driven not only by the need to extend their historical applicability in the ever-evolving integrated circuit (IC) and solar cell industries, but also by their potential uses in countless new applications. These include, for example, Si nanocrystals (Si-NC) as the host matrix and quantum dots (QDs) for photoluminescence applications; waveguides in nonlinear frequency combs for sensors and photonic devices for telecommunications; tunable light-emitting films for silicon-based light-emitting diodes (LEDs) in silicon-based monolithic optoelectronic integration; passivation / encapsulation nanostructures at gallium arsenide (GaAs) interfaces for compound semiconductor devices; and fundamental platforms for biomaterial integration in biochemical and medical applications.

[0004] The immense appeal of silicon-based thin films is driven by their highly attractive combination of physical, chemical, mechanical, electrical, and optoelectronic properties, making them one of the most widely used materials across a wide range of industries. Many of these industries share a common evolutionary drive toward using thermally and / or chemically sensitive substrates combined with heterogeneous device structures with smaller feature sizes. Consequently, research and development activities focus on the development and optimization of low-temperature deposition processes, such as direct and remote plasma-enhanced chemical vapor deposition (PE-CVD), laser-assisted CVD, mirror-enhanced plasma-enhanced chemical vapor deposition (MPECVD), porous hollow cathode radio frequency (RF) PECVD, and direct, remote, and glow discharge plasma-enhanced atomic layer deposition.

[0005] Despite this extensive research and development effort, significant challenges remain to be overcome to enable silicon-based thin films to be scaled up for heterogeneous device applications. On one hand, much of the PE-CVD and PE-ALD processes rely on the use of silanes (SiH4) and silane-type precursors. The inherent problems associated with using such chemicals are well-documented, including their ignition properties, increased thermal budget, and high hydrogen incorporation. Furthermore, PE-ALD processes using silane-type silicon sources suffer from substrate surface adsorption and nucleation issues, necessitating substrate surface pretreatment, which increases complexity and cost. Moreover, the resulting films often consist of varying concentrations of silicon, oxygen, and nitrogen, containing significant contaminants, and / or exhibiting Si-to-N and Si-to-O compositional gradients at the film's interfaces, volume, and surface regions.

[0006] For these reasons, it would be desirable to provide a thin film deposition technique that overcomes the aforementioned shortcomings of conventional deposition techniques by depositing high quality silicon-based thin films, such as (SiN x ) and silicon oxide (SiO2) and mixtures thereof, such as SiC x N y at low temperatures, while minimizing the number and complexity of substrate surface pretreatment steps, thereby maximizing process efficiency and productivity. SUMMARY

[0007] In one embodiment, the present invention is directed to a method for depositing a silicon nitride thin film onto a substrate in a reaction zone of a deposition chamber, said method comprising, in a single cycle: heating the substrate to a temperature of about 200°C to about 650°C; maintaining the substrate at about 200°C to about 650°C; providing a precursor comprising a gas phase of an N-alkyl substituted perhydridocyclotrisilazane to the reaction zone containing said substrate with a carrier gas and / or under vacuum; forming a monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a nitrogen-containing reactant; wherein the adsorbed N-alkyl substituted perhydridocyclotrisilazane monolayer reacts with the soft plasma and is converted to a discrete atomic or molecular layer of the silicon nitride thin film by dissociation and / or decomposition induced by or from the substrate surface; and removing the conversion byproducts from the reaction zone by a purge step using an inert gas and / or vacuum.

[0008] In a second embodiment, a method for depositing a silicon oxide thin film onto a substrate in a reaction zone of a deposition chamber, said method comprising, in a single cycle:

[0009] heating the substrate to a temperature of about 200°C to about 650°C;

[0010] maintaining the substrate at about 200°C to about 650°C;

[0011] providing a precursor comprising a gas phase of an N-alkyl substituted perhydridocyclotrisilazane to the reaction zone containing said substrate with a carrier gas and / or under vacuum; forming a monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of an oxygen-containing reactant; wherein the adsorbed N-alkyl substituted perhydridocyclotrisilazane monolayer reacts with the soft plasma and is converted to a discrete atomic or molecular layer of the silicon oxide thin film by dissociation and / or decomposition induced by or from the substrate surface; and removing the conversion byproducts from the reaction zone by a purge step using an inert gas and / or vacuum.

[0012] In a further embodiment, the present invention provides a method for depositing a silicon carbonitride film onto a substrate in a reaction zone of a deposition chamber, said method comprising, in a single cycle: heating the substrate to a temperature of about 2000C; maintaining the substrate at about 2000C; providing a precursor comprising a gas phase of an N-alkyl substituted perhydridocyclotrisilazane to the reaction zone containing said substrate with a carrier gas and / or under vacuum; forming a monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a nitrogen containing reactant; wherein the adsorbed monolayer of the N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted to a discrete atomic or molecular layer of the silicon carbonitride film by dissociation and / or decomposition induced by or from the substrate surface; and removing the conversion byproducts from the reaction zone by using an inert gas purge step and / or vacuum.

[0013] In another embodiment, the present invention provides a method for depositing a silicon film onto a substrate in a reaction zone of a deposition chamber, said method comprising, in a single cycle: heating the substrate to a temperature of about 2000C to about 6500C; maintaining the substrate at about 2000C to about 6500C; providing a precursor comprising a gas phase of an N-alkyl substituted perhydridocyclotrisilazane to the reaction zone containing said substrate with a carrier gas and / or under vacuum; forming a monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a hydrogen containing reactant; wherein the adsorbed monolayer of the N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted to a discrete atomic or molecular layer of the silicon film by dissociation and / or decomposition induced by or from the substrate surface; and removing the conversion byproducts from the reaction zone by using an inert gas purge step and / or vacuum.

[0014] BRIEF DESCRIPTION OF DRAWINGS

[0015] The principles of the application will be better understood in connection with the following detailed description of preferred embodiments, when considered in connection with the accompanying drawings. In the drawings, the presently preferred embodiments are illustrated. It is to be understood, however, that the application is not limited to the specific arrangements and instrumentalities shown. In the drawings:

[0016] Figure 1 is a plot of the experimental vapor pressure data of TICZ and the fit of the Antoine equation over the range of 0.14 to 760 Torr.

[0017] Figure 2 is an optimized SiN x Process window schematic.

[0018] Figure 3is an in-situ real-time ellipsometry plot of film thickness versus deposition time at 0.4, 1.0, 2.0, 3.0, and 5.0 seconds of TICZ exposure time for a substrate temperature of 200 °C.

[0019] Figure 4 is an in-situ real-time ellipsometry plot of film thickness versus deposition time for substrate temperatures of 150, 175, 200, 225, 300, and 350 °C.

[0020] Figure 5 is SiN x is an in-situ real-time ellipsometry plot of film thickness versus deposition time for the first minute of processing.

[0021] Figure 6 is SiN x XPS plot of Zn, Si, N, C, and O concentration versus penetration depth in the thin film.

[0022] Figure 7 is SiN x XPS plot of Zn, Si, N, C, and O concentration versus penetration depth in the thin film.

[0023] Figure 8 is SiN x High resolution XPS spectra of Si2p, N1s, C1s, and O1s binding energy versus penetration depth in the thin film.

[0024] Figure 9 is SiN x High resolution XPS spectra of Si2p, N1s, C1s, and O1s binding energy versus penetration depth in the thin film.

[0025] Figure 10 is SiC x N y XPS depth profile of Zn, Si, N, C, and O concentration in the film.

[0026] Figure 11 is SiC x N y XPS depth profile of Zn, Si, N, C, and O concentration in the film.

[0027] Figure 12 is SiC x N y High resolution XPS core level spectra of Si2p, N1s, C1s, and O1s binding energy versus penetration depth in the thin film.

[0028] Figure 13SiC deposited at 150 °C x N y High resolution XPS core level spectra of Si2p, Nls, Cls, and Ols binding energies versus depth in the thin film.

[0029] Figure 14 SiC with substrate temperature of 150 °C and TICZ pulse times of 0.1 s, 0.2 s, 0.4 s, and 0.8 s x N y In-situ real-time angle resolved ellipsometry plots of film thickness versus deposition time.

[0030] Figure 15 SiC with substrate temperature of 30, 60, 90, 120, 150, and 170 °C x N y In-situ real-time angle resolved ellipsometry plots of film thickness versus deposition time. DETAILED DESCRIPTION

[0031] Aspects of the present invention relate to low to moderate temperature vapor deposition processes for depositing Si-based thin films onto substrates in a deposition chamber reaction zone. The processes include, in a cycle, heating a substrate to a desired temperature and maintaining the substrate at that temperature, providing a N-alkyl substituted perhydridocyclotrisilazane precursor comprising a gas phase with a carrier gas and / or under vacuum to a reaction zone containing the substrate, forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, optionally removing unreacted perhydridocyclotrisilazane and byproducts thereof from the reaction zone by a purge step using an inert gas and / or vacuum, and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of another chemical species or co-reactant, wherein the adsorbed N-alkyl substituted perhydridocyclotrisilazane monolayer reacts with the soft plasma and is converted into a discrete atomic or molecular layer of the Si-based thin film by dissociation and / or decomposition induced by or from the substrate surface, removing byproducts of the conversion from the reaction zone by a purge step using an inert gas and / or vacuum. The individual cycle is then repeated as many times as necessary to form a silicon-based thin film having a desired or predetermined thickness. As detailed below, the appropriate substrate temperature and composition of the soft plasma are determined by the desired chemical composition of the silicon-based thin film, e.g., silicon nitride, silicon carbon nitride, silicon oxide, or silicon.

[0032] The term "thin film" is well known in the art and can include films having a thickness ranging from a few nanometers to a few microns. As noted above, such film thickness is controlled by the number of cycles performed.

[0033] In some embodiments, the conversion of the adsorbed monolayer to a discrete atomic or molecular layer can be assisted or achieved by energy transfer from an energy source such as a heated substrate. For example, surface-induced processes such as energy transfer from the substrate (thermal exposure), remote or direct plasma application, oxidation, and / or reduction can be used to initiate or promote the conversion of the adsorbed monolayer to the final deposited film.

[0034] The term "soft plasma" refers to a plasma-induced process in which minimal energy is applied to the target film or substrate, resulting in very little or no mechanical, chemical, physical, or electrical damage to the film and substrate. Similarly, soft plasma refers to a plasma-induced process that imparts energy to the target molecule that is below the threshold for the target molecule to break, fragment, or decompose. In contrast, soft plasma is designed to impart sufficient activation energy to the precursor to enable controlled decomposition in conjunction with additional thermal energy sources, preferably on the substrate surface.

[0035] The methods described herein use N-alkyl substituted perhydridocyclotrisilazanes as silicon source precursors. Unlike perhydridocyclotrisilazanes with methyl groups on the N atoms, this class of silazanes contains alkyl radicals with at least two carbon atoms on each N atom, providing a low to moderate temperature SiN x mechanism. In contrast, the simple methyl groups in methyl substituted perhydridocyclotrisilazanes require higher temperatures to form films and result in films with higher carbon concentrations. This can be due to the lack of a low energy elimination mechanism for these methyl groups.

[0036] The favorable chemical structure and bonding configuration of the N-alkyl substituted perhydridocyclotrisilazanes have been designed such that the alkyl groups can be cleanly removed at low to moderate temperatures to yield pure silicon-based thin films. In addition, the presence of H atoms on the Si atoms minimizes steric hindrance and allows the precursor molecules to more easily access reactive substrate surface sites, whether these sites are H-terminated (e.g., Si) or HO-terminated (e.g., SiO2). In other words, the adsorption of the precursor to the substrate surface and some partial decomposition resulting from the possible breaking of ligands occurs instantaneously upon contact with the substrate. This feature is significant because thin film nucleation and growth can occur instantaneously in the first cycle without a latency period, eliminating the need for substrate surface pretreatment that results in additional complexity and increased cost of ownership as reported in the prior art.

[0037] The film forming process as described in the present invention is plasma activated, rather than plasma enhanced or plasma assisted. In a plasma activated process, the precursor exposure step is conducted thermally without the involvement of plasma, while the co-reactant (e.g., NH3, N2, N2+H2, hydrazine, oxygen, ozone, water, or H2) is introduced in a direct or remote soft plasma. Thus, the precursor adsorption step is activated by thermal and chemical energy from the substrate rather than from plasma, which enables the precursor (or partial precursor species, since some ligands or attached radicals and groups of the precursor can be eliminated upon binding to the substrate) to physically or chemically adsorb in a conformal manner to various substrate surface topographies, including, for example, high aspect ratio via and trench structures. As a result, the subsequent remote or direct co-reactant plasma will lead to the formation of the desired film with the same thickness across the substrate surface, including in highly aggressive device geometries.

[0038] The process as described in the present invention is conducted at substrate temperatures that result in partial or complete decomposition of the pulsed precursor upon contact with the substrate during each exposure cycle, rather than being limited to simple physical or chemical adsorption reactions of the intact precursor. The co-reactant is subsequently introduced to complete the decomposition reaction and / or eliminate reaction byproducts to ensure a clean film. Thus, the described process requires lower thermal, chemical, or plasma energy to grow the target thin film, since the precursor is already partially decomposed upon reaching the substrate surface.

[0039] The decomposition of the precursor in the process as described in the present invention is caused by three processes working in concert: adsorption of the precursor to the substrate and partial elimination of some ligands, thermal energy from the substrate, and soft plasma activation.

[0040] Suitable substrates include, but are not limited to, substrates formed from a material selected from the group consisting of silicon, silicon oxide, copper, platinum, titanium, titanium nitride, tantalum, and tantalum nitride.

[0041] The process as described in the present invention is equally applicable to the reaction of N-alkyl substituted perhydrocyclotrisilazanes with a nitrogen source, such as, but not limited to, a direct or remote NH3, N2, N2+H2, hydrazine, or methylamine soft plasma, to form silicon nitride (SiN x ); with an oxygen source, such as, but not limited to, a direct or remote ozone, water, or O2 soft plasma, to form silicon oxide (SiO2); and with an active hydrogen source, such as a direct or remote H2 soft plasma, to form pure Si. The described process can also be applied to form SiC x N y compound thin films by decomposition of N-alkyl substituted perhydrocyclotrisilazanes through exposure to a direct or remote soft plasma of nitrogen or carbon containing chemicals or co-reactants. The ratio of C to N (C / N) in the thin film is adjusted by controlling the substrate temperature and the duration of the co-reactant pulse.

[0042] Specifically, controlling the substrate temperature in the reaction zone of the deposition chamber affects the chemical composition of the resulting silicon-containing thin film. Specifically, depending on the chemical structure and bonding configuration of the N-alkyl substituted perhydrocyclotrisilazane, the energy of the soft plasma reacting with the source precursor at higher but moderate substrate temperatures (about 200 °C to about 650 °C, preferably about 200 °C to about 350 °C) results in the formation of SiN thin films, while low substrate temperatures (room temperature to about 200 °C, preferably about 30 °C to about 200 °C) result in the formation of SiC thin films consisting of a matrix of simple Si-C and Si-N bonds. The SiC thin films are formed at low substrate temperatures (room temperature to about 200 °C, preferably about 30 °C to about 200 °C) and are composed of a matrix of simple Si-C and Si-N bonds. The SiN thin films are formed at higher but moderate substrate temperatures (about 200 °C to about 650 °C, preferably about 200 °C to about 350 °C) and are composed of a matrix of simple Si-N bonds. x N y thin films, do not contain C-N bonds. For the purposes of the present invention, the term "room temperature" can be understood to refer to a temperature from about 20 °C to about 27 °C. In both processes, direct or remote soft plasma exposure of a nitrogen-containing reactant (such as, but not limited to, NH3, N2, N2+H2, hydrazine, or methylamine) to a monolayer adsorbed on the substrate. Direct or remote soft plasma of carbon-containing chemicals such as acetylene can also be used to form silicon carbonitride thin films. The adsorbed N-alkyl substituted perhydrocyclotrisilazane monolayer reacts with the soft plasma and is converted into a discrete atomic or molecular layer of silicon carbonitride thin film through dissociation and / or decomposition caused by or induced by the substrate surface.

[0043] The process as described in the present invention is distinctly different from plasma-enhanced chemical vapor deposition (PE-CVD) in that the formation of the film on the surface is independent of the gas-phase interaction of the precursors and plasma. While a purge step, i.e., a mechanism to remove unadsorbed (unreacted) precursors and co-reactants as well as byproducts from the gas phase by a vacuum or inert gas stream, is not required, it is preferred in some embodiments to eliminate the possibility of unwanted gas-phase reactions. Such byproducts of the reaction of the parent precursors with the co-reactants and their subsequent decomposition include, for example, ligands and partial ligands from the parent molecules and partially decomposed precursors. Byproducts can also include partially decomposed co-reactant species and entities formed from the precursor ligands and co-reactant species.

[0044] In one embodiment, aspects of the present invention relate to the development and optimization of a plasma-activated process from a perhydrocyclotrisilazane, 1,3,5-tris(isopropyl)cyclotrisilazane (TICZ, C9H 27 N3Si3), which contains three C atoms in the form of propyl groups on each N. The latter is eliminated at moderate temperatures in the form of the gaseous byproduct propylene, as shown in Formula 1:

[0045]

[0046] Using this perhydrocyclotrisilazane, SiN xthin films (where 0 < x < 1.33). Thus a method of forming SiN x thin films at moderate temperatures (substrate temperatures of about 200°C to about 650°C, preferably about 200°C to about 350°C) using N-alkyl substituted perhydridocyclotrisilazane precursors and nitrogen containing soft plasma co-reactants is provided, and in preferred embodiments using TICZ and soft remote ammonia (NH3) plasma co-reactants. It is understood that the range of substrate temperatures includes all temperatures within the range, thus temperatures of about 200°C to about 650°C include temperatures such as about 225°C, about 250°C, about 275°C, about 300°C, about 325°C, about 300°C, about 325°C, about 350°C, about 375°C, about 400°C, about 425°C, about 450°C, about 475°C, about 500°C, about 525°C, about 550°C, about 575°C, about 600°C, about 625°C, about 650°C, and all temperatures therebetween.

[0047] The exemplary process described for depositing such silicon nitride thin films onto a substrate in a reaction zone of a deposition chamber includes, in a single cycle: heating the substrate to about 200°C to about 650°C, preferably about 200°C to about 350°C; maintaining the substrate at about 200°C to about 650°C, preferably about 200°C to about 350°C; providing a precursor comprising a gas phase of N-alkyl substituted perhydridocyclotrisilazane with a carrier gas and / or under vacuum to a reaction zone containing the substrate; forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a nitrogen containing reactant; wherein the adsorbed monolayer of N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted to a discrete atomic or molecular layer of silicon nitride thin film by dissociation and / or decomposition effected by or induced by the substrate surface; and removing by-products of the conversion from the reaction zone by a second purge step using an inert gas and / or vacuum. The single cycle is then repeated until a predetermined thickness of thin film is obtained. The nitrogen containing reactant includes NH3, N2, mixtures of N2and H2, methylamine and / or hydrazine; NH3is presently preferred.

[0048] In some embodiments, after forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, a second purge step using an inert gas and / or vacuum removes unreacted N-alkyl substituted perhydridocyclotrisilazane and by-products thereof from the reaction zone.

[0049] The resulting SiN x thin films (where 0 < x < 1.33) were analyzed for composition and optical properties, and wet etch rates were determined by standard IC industry etching solutions. These results are summarized and discussed below.

[0050] Thus, by the method of the present invention, high quality silicon nitride (SiN 27 ) films can be formed on substrates, such as silicon oxide (SiO2), from the source precursor 1,3,5-tris(isopropyl)cyclotrisilazane (TICZ, C9H x N3Si3) and a remote ammonia (NH3) soft plasma at optimized substrate temperature windows of about 200 °C to about 350 °C. Briefly, the process comprises four steps: a plasma-free TICZ pulse, an optional N2 purge, a NH3 plasma pulse, and a N2 purge. As described below, as-deposited SiN x films prepared by the process described herein were analyzed by ellipsometry and X-ray photoelectron spectroscopy (XPS). Wet etch rates (WER) were determined using a standard solution consisting of 0.5% hydrofluoric acid (HF) in deionized water. XPS analysis yielded a ~1 : 1 Si:N ratio across the entire substrate temperature range and verified the formation of SiN x growth exhibited non-self-limiting pulse behavior. For films grown at substrate temperatures above 200 °C, they also yielded an average refractive index of ~1.8 for SiNx.

[0051] The main findings of the development and optimization of SiN x film low temperature processes using the source precursor TICZ with NH3 plasma are as follows. TICZ was chosen because it contains three C atoms in the form of propyl groups on each N, which are easily eliminated at moderate temperatures in the form of the gaseous byproduct propylene. As described below, TICZ can also be obtained in high yield and high purity from readily available starting materials, thus proving its suitability for mass production. This study identified an optimized substrate temperature window of 200 to 350 °C for the formation of high quality Si 1.0 :N 1.0 films. Wet etching studies in a standard IC industry solution consisting of 0.5% HF in deionized H2O showed feasible etch rates, which are competitive compared to those reported in the literature. Ellipsometric analysis of the film nucleation and growth characteristics showed that film formation occurred instantaneously in the first deposition cycle, with no incubation period, in contrast to many previous reports in the literature for ALD and CVD SiN x , thus eliminating the need for substrate surface pretreatment, which leads to additional complexity and increased cost of ownership. These results suggest that SiN x using TICZ as a silicon source precursor is a viable option for incorporation into emerging heterogeneous device structure manufacturing process flows.

[0052] In another embodiment, the present invention is directed to forming SiC at low temperature (substrate temperature from room temperature to about 200 °C) using N-alkyl substituted perhydrotrisilazane precursors and nitrogen or carbon containing soft plasma co-reactants x N y (0.40 < x < 1.67 and 0.67 < y < 0.86) thin films, and in preferred embodiments, using TICZ and remote ammonia (NH3) soft plasma co-reactants. Such an exemplary process for depositing silicon carbonitride thin films onto a substrate in a reaction zone of a deposition chamber includes, in a single cycle: heating the substrate to a temperature from room temperature to about 200 °C; maintaining the substrate at a temperature from room temperature to about 200 °C; providing a precursor comprising a gas phase of N-alkyl substituted perhydrotrisilazane with a carrier gas and / or under vacuum to a reaction zone containing the substrate; forming a monolayer of N-alkyl substituted perhydrotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a nitrogen containing reactant; wherein the adsorbed N-alkyl substituted perhydrotrisilazane monolayer reacts with the soft plasma and is converted to a discrete atomic or molecular layer of silicon carbonitride thin film by dissociation and / or decomposition due to or induced by the substrate surface; and its byproducts of conversion are removed from the reaction zone by use of an inert gas purge step and / or vacuum. The single cycle is then repeated as many times as needed until a predetermined thickness of SiC x N y thin film is obtained. The nitrogen containing chemical species or co-reactant can be, for example, but not limited to, NH3, N2, a mixture of N2and H2, methylamine, and / or hydrazine; NH3is presently preferred. The carbon containing chemical species or co-reactant can be, for example, acetylene.

[0053] It is understood that the range of substrate temperatures includes all temperatures within the range, and thus, a temperature from room temperature to about 200 °C includes, for example, about 20 °C, about 25 °C, about 30 °C, about 45 °C, about 50 °C, about 60 °C, about 70 °C, about 80 °C, about 90 °C, about 100 °C, about 110 °C, about 120 °C, about 130 °C, about 140 °C, about 150 °C, about 160 °C, about 170 °C, about 180 °C, about 190 °C, and about 200 °C, and all temperatures therebetween.

[0054] In some embodiments, after forming a monolayer of N-alkyl substituted perhydrotrisilazane by adsorption to the substrate surface, a second purge step using an inert gas and / or vacuum removes unreacted N-alkyl substituted perhydrotrisilazane and its byproducts from the reaction zone.

[0055] Thus, by employing the methods described herein, high quality SiC xN y Thin films. Briefly, the process involves four steps: thermal adsorption of TICZ onto the substrate at low temperature (TICZ pulse without plasma), optional nitrogen (N2) purge, soft NH3 remote plasma step, and N2 purge. These steps are repeated until the desired film thickness is achieved. The ratio of C to N in the film can be adjusted by controlling the substrate temperature in the range of room temperature to about 200 °C, preferably about 30 °C to about 200 °C. The deposition process was analyzed in-situ using spectroscopic ellipsometry and the thin films were analyzed in-situ by X-ray photoelectron spectroscopy (XPS). The results of this study show that the combination of reduced substrate thermal budget and soft remote plasma provides a low energy environment for the growth of SiC x N y The controlled deposition of protective coatings on thermally fragile, chemically sensitive substrates, including plastics and polymers, is provided in an optimal low energy environment.

[0056] As described below, it has been discovered that the low temperature (near room temperature) growth of SiC x N y with 0.40 < x < 1.67 and 0.67 < y < 0.86 is generated in the substrate x N y Thin films with substrate temperatures ranging from 30 to 150 °C. XPS analysis indicates that the SiC x N y Thin films are composed primarily of a temperature independent matrix of simple cross-linked Si-C and Si-N bonds. In-situ real-time angle resolved ellipsometry indicates that all thin films grow in the plasma pulse state with instantaneous film nucleation and growth, with no incubation period similar to that reported in the ALD and P-CVD literature. This feature, which eliminates ex-situ or in-situ pre-deposition substrate surface treatments, improves process efficiency and reduces process steps and cost of ownership, makes the described SiC x N y Process is attractive from a manufacturing perspective. Thus, these findings indicate that the application of a soft remote plasma with reduced substrate thermal budget, where the TICZ and NH3 co-reactants react only at the substrate surface, constitutes a promising approach for the growth of SiC x N y protective coatings for potential applications requiring thermally fragile, chemically sensitive substrates, including plastics and polymers.

[0057] In a further embodiment, the present application is directed to a method for depositing a silicon oxide film onto a substrate in a reaction zone of a deposition chamber. The method comprises, in a single cycle: heating the substrate to a temperature of about 200 °C to about 650 °C, preferably about 200 °C to about 350 °C; maintaining the substrate at about 200 °C to about 650 °C, preferably about 200 °C to about 350 °C; providing a precursor comprising a gas phase of N-alkyl substituted perhydridocyclotrisilazane with a carrier gas and / or under vacuum to a reaction zone containing the substrate; forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of an oxygen containing reactant; wherein the adsorbed monolayer of N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted to a discrete atomic or molecular layer of a silicon oxide film by dissociation and / or decomposition induced by or from the substrate surface; and removing the conversion byproducts from the reaction zone by a second purge step using an inert gas and / or vacuum. The single cycle is then repeated as many times as necessary to achieve a predetermined thickness of the film. The oxygen containing reactant includes, but is not limited to, ozone, O2, and water. The preferred N-alkyl substituted perhydridocyclotrisilazane is TICZ.

[0058] It is understood that the range of substrate temperatures includes all temperatures within the range, thus a temperature of about 200 °C to about 650 °C includes temperatures such as about 225 °C, about 250 °C, about 275 °C, about 300 °C, about 325 °C, about 300 °C, about 325 °C, about 350 °C, about 375 °C, about 400 °C, about 425 °C, about 450 °C, about 475 °C, about 500 °C, about 525 °C, about 550 °C, about 575 °C, about 600 °C, about 625 °C, about 650 °C, and all temperatures therebetween.

[0059] In some embodiments, after forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, a second purge step using an inert gas and / or vacuum removes unreacted N-alkyl substituted perhydridocyclotrisilazane and its byproducts from the reaction zone.

[0060] In a further embodiment, the present application provides a method for depositing a silicon thin film onto a substrate in a reaction zone of a deposition chamber, said method comprising, in a single cycle: heating the substrate to a temperature of about 200°C to about 650°C, preferably about 200°C to about 350°C; maintaining the substrate at about 200°C to about 650°C, preferably about 200°C to about 350°C; providing a precursor comprising a gas phase of an N-alkyl substituted perhydridocyclotrisilazane to the reaction zone containing said substrate with a carrier gas and / or under vacuum; forming a monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a hydrogen containing reactant; wherein the adsorbed N-alkyl substituted perhydridocyclotrisilazane monolayer reacts with the soft plasma and is converted to a discrete atomic or molecular layer of the silicon thin film by dissociation and / or decomposition induced by or from the substrate surface; and removing the conversion by-products from the reaction zone by a second purge step using an inert gas and / or vacuum. The single cycle is then repeated as many times as necessary to achieve a predetermined thickness of the thin film. The hydrogen containing chemical species or co-reactant can be, for example, but not limited to, H2. The preferred N-alkyl substituted perhydridocyclotrisilazane is TICZ.

[0061] It is understood that the range of substrate temperatures includes all temperatures within the range, thus a temperature of about 200°C to about 650°C includes, for example, but not limited to, about 225°C, about 250°C, about 275°C, about 300°C, about 325°C, about 300°C, about 325°C, about 350°C, about 375°C, about 400°C, about 425°C, about 450°C, about 475°C, about 500°C, about 525°C, about 550°C, about 575°C, about 600°C, about 625°C, about 650°C, and all temperatures therebetween.

[0062] In some embodiments, after forming a monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, a second purge step using an inert gas and / or vacuum is used to remove unreacted N-alkyl substituted perhydridocyclotrisilazane and its by-products from the reaction zone.

[0063] The present application will now be described with reference to the following non-limiting examples.

[0064] Example 1: Formation of SiN thin films

[0065] Synthesis of precursors

[0066] Under an argon atmosphere, 909 grams of methyl-tert-butyl ether was charged into a 5 liter four necked flask equipped with a cooling bath, overhead stirrer, bottle thermometer, liquid under-pipette and dry ice condenser. The mixture was cooled to -40 °C and then 303.0 grams (3 moles) of dichlorosilane was slowly added to the bottle. Then 364.7 grams (6.0 moles) of isopropylamine was added through the pipette over a period of 2.5 hours at a temperature range of -30 to -20 °C. After the addition was complete, the reaction mixture was slowly warmed to 25 °C and stirred at this temperature for 8 to 14 hours. This step was followed by the addition of 177.4 grams (3 moles) of isopropylamine at a temperature range of 0 to 40 °C, followed by the addition of 227.3 grams of methyl-tert-butyl ether. The mixture was stirred for 6 to 16 hours and monitored by gas chromatography (GC). Then the reaction was filtered and the solvent was removed from the filtrate under reduced pressure at less than 50 °C. The filtration process was repeated and the clear filtrate was fractionated to obtain 64.5 grams (24.66) of TiCZ.

[0067] TICZ vapor pressure was determined from a combination of distillation temperature, pressure reading (<10 Torr) and pressure cell DSC measurement (>10 Torr). The latter was performed using a TA Instruments Pressure DSC 25P instrument with a Tzero Hermetic Pinhole (75 pm) cap, 2-5 mg sample size and a 15 °C / min ramp rate. Figure 1 Actual vapor pressure data from distillation and DSC measurements are provided, along with an Antoine equation fit [Log(P) = A - B / (C + T)] over the range of 0.14 to 760 Torr.

[0068] Process conditions for SiN thin film deposition

[0069] A Picosun R-200 research system equipped with a sample load lock to maintain cleanliness and vacuum integrity of the reaction chamber and a remote inductively coupled plasma (ICP) power source was employed in process development and optimization. All depositions were performed on substrates consisting of 1000 nm thick thermal grown silicon dioxide on n-doped Si wafers, purchased from Addison Engineering. The samples were loaded as-is and subjected to an in-situ NH3plasma clean at a plasma frequency of 13.56 MHz and a plasma power of 2000 W for 5 minutes prior to each deposition run.

[0070] The TICZ precursor was charged into a dedicated bubbler, which was connected to the Picosun precursor manifold system and heated to 50 °C. All delivery lines were also heated to 90 °C to prevent premature condensation of the precursor before entering the reaction chamber. N2gas was used as the carrier gas and set to 100 seem.

[0071] SiN from reactions of TICZ and NH3 plasma x Process development and optimization was performed in two stages. In the first "proof of concept" stage, a set of systematic screening experiments were performed to determine the optimal values of TICZ pulse, purge step, and NH3 plasma pulse duration, as well as N2 purge gas flow, NH3 remote plasma flow, and plasma power. In the second "process optimization" stage, the key experimental parameters were set as shown in Table 1, and the process was run at substrate temperatures ranging from 50 to 350 °C in 50 °C intervals. For substrate temperatures of 50, 150, 200, 250, 300, and 350 °C, the parent exposure and plasma pulse duration and purge time were identical, except that no parent purge time was applied in the 350 °C run. The NH3 remote plasma frequency, flow rate, and power were set at 13.56 MHz, 40 seem, and 2000 W, respectively. The samples were subsequently transferred to a load lock system and cooled to room temperature in a N2 atmosphere before being removed from the Picosun system. Figure 2

[0072] For XPS analysis, SiN x samples were covered with approximately 10-15 nm thick zinc oxide (ZnO x ) layers to prevent surface contamination during transport and handling. The ALD ZnO x process was run for 100 cycles using diethyl zinc (DEZ) as the zinc source and water as the oxygen source. The ZnO x was then grown in situ immediately after SiN x deposition at the same temperature, except in the case of the 50 °C sample, where the temperature was increased to 150 °C for ZnO x deposition. The process consisted of four steps: 0.1 s DEZ pulse, 5 s N2 purge, 0.1 s water vapor pulse, 5 s N2 purge.

[0073] Analysis techniques

[0074] In-situ, real-time, angle-resolved ellipsometry analysis was performed using a Woollami SE ellipsometer over a wavelength range of 400 to 1000 nm. The ellipsometer system was mounted directly on the P-CVD (pulsed CVD) reaction chamber, with the incident beam illuminating the substrate through a quartz glass window at an incident angle of 60.8°, and the reflected beam captured by a detector. The resulting data was analyzed using CompleteEASE software. The substrate was modeled as a hot SiO2 layer approximately 1000 nm thick on Si. The thickness of the SiO2 layer was measured in-situ prior to each P-CVD run.

[0075] ​XPS was performed at Eurofins EAG Materials Science, LLC on a PHI Quantum 2000 system. X-rays were generated from a monochromatic Al k α source at 1486.6 eV and directed at the sample at an a ± 23° take-off angle and 45° grazing angle. Ar + ion gun at 2 keV, 4 mm x 2 mm raster, and 3.8 nm / min sputter rate. No deconvolution was applied to the data as the Si, N, C, and O peaks were well separated from each other. All data processing (integration) was performed using CasaXPS software by Casa Software Ltd. Images were generated using MultiPak software by Ulvac-phi. Depth profiles were generated using Microcal Origin by Microcal Software, Inc. High resolution XPS peak assignments were made following the calibration procedure described in ISO 15472:2010 "Surface chemical analysis - X-ray photoelectron spectrometers - Energy scale calibration".

[0076] Wet etch studies were performed at room temperature using an IC industry standard solution consisting of 0.5% hydrofluoric acid (HF) in deionized water.

[0077] Precursor analysis

[0078] Another advantage of 1,3,5-tris(isopropyl)cyclotrisilazane (TICZ, C9H 27 N3Si3) is that, as mentioned above, it is produced in high yield and purity from readily available starting materials. This ensures its suitability for mass production. Relevant properties of TICZ are shown in Table I, and its vapor pressure versus temperature parameters are shown in Figure 1. It is noted that the precursor synthesis recipe described earlier can also produce other analogs, such as 1,3,5-tris(ethyl)cyclotrisilazane and 1,3,5-tris(tert-butyl)cyclotrisilazane, which have different volatility and deposition characteristics. Figure 1

[0079] Table I Chemical structure and properties of TICZ

[0080]

[0081] Ellipsometric analysis

[0082] Figure 3 ​In-situ real-time ellipsoidal plots of film thickness versus deposition duration were plotted for films grown at a substrate temperature of 200 °C with TICZ pulse times of 0.4 s, 1.0 s, 2.0 s, 3.0 s, and 5.0 s. As shown in the plots, the film thickness continuously increases with the precursor pulse time without saturation, regardless of the precursor pulse time. This behavior indicates that the TICZ adsorption step is not self-limiting and supports the growth of SiN... x Thin film growth was not determined by the ALD process. The film thickness showed the same dependence on pulse time across the entire substrate temperature range studied (from 50°C to 350°C), indicating that no film was formed via the ALD growth mode within any of the process windows studied.

[0083] Similarly, Figure 4 and Figure 5 In-situ real-time ellipsometric measurements of film thickness versus deposition time are displayed at substrate temperatures of 150, 175, 200, 225, 300, and 350 °C. As expected, Figure 4 The film thickness was shown to increase with increasing deposition time. However, a gradual decrease in the slope of each film thickness curve was also observed with increasing substrate temperature. This decrease indicates that the growth rate (GPC) per cycle decreases with increasing substrate temperature. This suggests that the decrease in GPC is attributed to a reduction in the precursor vapor partial pressure in the reaction zone near the substrate. This reduction is thought to be possible due to the geometry of the deposition chamber, which induces additional heating at the point where the precursor enters the reactor, causing some precursors to decompose before reaching the reaction zone as the substrate temperature increases. Alternatively, this reduction could be due to a higher frequency of recombination of precursor materials and associated ligands with increasing thermal budget, and their subsequent desorption from the substrate surface, thus limiting the reaction rates of TICZ and NH3.

[0084] also, Figure 5 The film formation was observed to occur instantaneously during the first deposition cycle, without any latency or delay in film nucleation and growth. This is consistent with the findings regarding SiN produced by ALD and CVD. x This contrasts with many previous reports in the literature. This feature is important because it eliminates the need for substrate surface pretreatment, thereby eliminating the need to introduce SiN into the fabrication process of heterogeneous device structures. x The increased complexity and cost of deposition. Furthermore, Table II presents the film thickness obtained by the elliptic polarization method, the growth rate per cycle (GPC), and the refractive index of the deposited SiNx film as a function of substrate temperature.

[0085] Table II shows the SiN determined by elliptic polarization method, XPS, and wet etching. x Selected characteristics

[0086]

[0087]

[0088] XPS analysis

[0089] XPS depth profile analysis also confirmed the selected film thicknesses. SiN x concentrations in the films were evaluated by XPS depth profile analysis as a function of penetration depth, Figure 6 and 7 representative high resolution XPS spectra of as-deposited SiN x films grown at substrate temperatures of 200 °C and 300 °C, respectively.

[0090] For films grown at substrate temperatures of 50 °C and 150 °C, the measured C concentrations were reduced by ~42 at% and ~15 at%, respectively. As shown in Figure 6 , this value dropped below the detection limit of the XPS above substrate temperatures of 200 °C. Thus, the XPS results indicate that 200 °C provides the minimum thermal budget required for efficient reaction of TICZ and NH3, resulting in complete dissociation of the precursors and removal of reaction byproducts from the deposition zone. Likewise, for films grown at substrate temperatures of 50 °C and 150 °C, O concentrations of ~11 at% and ~6 at% were recorded, respectively. As shown in Figure 6 , this value dropped to ~5 at% above substrate temperatures of 200 °C. The O dopant resulted from O diffusion during the in-situ P-CVD zinc oxide (ZnO x ) overlayer deposition step.

[0091] Table III provides representative SiN x atomic concentrations in a number of films grown at 200 °C, 250 °C, and 300 °C with a depth of ~25 nm. The data in Table III, as well as Figure 6 and Figure 7 , indicate that samples deposited above 200 °C consist of Si:N ratio of ~1 : 1.

[0092] High resolution XPS spectra of Si2p, N1s, C1s, and O1s binding energies as a function of penetration depth for SiN x films deposited at 200 °C and 300 °C are shown in Figure 8 and 9 , respectively. The data indicate that both sets of films consist of SiN phases with low concentrations of O and almost no C dopant. It should be noted that the N1s spectra contain a main peak attributed to N(-Si)3 due to Si-N bonding, and a minor peak attributed to O-N(-Si)2, which is associated with silicon oxynitride (Si x N y O z ).

[0093] Table III. Representative SiNx atomic concentrations (at%) in films grown at 200, 250, and 300 °C

[0094]

[0095] wet etching rate

[0096] Wet etching studies were conducted using an IC industry standard solution consisting of 0.5% hydrofluoric acid (HF) in deionized water. The results are summarized in Table II. Wet etching rates for films deposited at 300 °C were observed to be competitive with those reported in the prior art, including, for example, etching in a milder etch solution consisting of 1:300 HF:H₂O for LPCVD films grown at 770 °C and PE-ALD films deposited at 250 °C; and for PE-ALD films grown between 270 and 350 °C, treated in a more dilute wet etch solution consisting of 1:500 HF:H₂O.

[0097] Example 2: Formation of SiCxNythin films

[0098] Experimental sedimentation conditions

[0099] All experiments were conducted in the same Picosun R-200 research and development reactor described above. SiC x N y The thin film growth experiments were conducted in two phases. In the first screening phase, systematic scope-definition experiments were performed to establish optimized operating parameters, including process operating pressure, remote NH3 plasma power, precursor, NH3, and N2 flow rates, the length of the pre-deposition plasma treatment step, and the duration of the TICZ, N2 purging, and remote NH3 plasma pulse steps. Once this phase was completed and an appropriate set of experimental parameters was determined, the second process optimization phase was implemented to determine the SiC... x N y The composition, physical and chemical properties of the plasma are shown as a function of substrate temperature ranging from 30°C to 200°C. During this stage, the NH3 flow rate was kept constant at 40 sccm, while the remote plasma power and frequency were set to 2000 W and 13.56 MHz, respectively. Table IV summarizes the key operating parameters.

[0100] Table IV. Soft-remote-range plasma SiC x N y Key process parameters for deposition

[0101]

[0102]

[0103] SiC x N y After growth and operation, an in-situ deposit of zinc oxide (ZnO) approximately 10 to 15 nm thick is formed. x A coating is applied to prevent SiC from being damaged when exposed to air and during subsequent transportation and handling. x N y Pollution. For ZnO x The procedure employs a standard ALD process. The substrate temperature is maintained at the same level as that of SiC. x N y The values ​​are the same for the deposition steps, except for SiC at 50℃. x N y Regarding the membrane, for ZnO x The growth process involves increasing the temperature to 150℃. Ald ZnO x The process uses diethylzinc (DEZ) and water (H2O) as the Zn and O source reactions, respectively: involving a 0.1s DEZ pulse and a 0.1s H2O vapor pulse, separated by a 5s N2 purge.

[0104] At the end of each deposition run, the samples were transferred back to the load-locking system and kept under an N2 atmosphere until they cooled to room temperature before being removed from the Picosun system.

[0105] Analytical techniques

[0106] To study SiC x N y The composition and chemical bonding properties of the membrane were analyzed using the same analytical techniques as described above.

[0107] XPS Analysis

[0108] Table V shows the representative atomic concentration percentages of Si, C, N, and O in films deposited at 50, 150, and 200 °C. These values ​​were determined by quantitative XPS analysis, such as... Figure 10 and 11 The figures show SiC deposited at 50 and 150 °C, respectively. x N y sample.

[0109] Table V shows a large number of SiC substrates grown at different substrate temperatures. x N y Representative atomic concentration in thin films

[0110] (Using at% as the unit, rounded to the nearest integer)

[0111]

[0112]

[0113] The oxygen content in the film was about 10 at% at 50 °C and dropped to 3-5 at% at higher temperatures. The presence of this small concentration of O can be due to the subsequent in-situ ALD ZnO x H2O with SiC x N y reaction. It can also be due to plasma etching issues of the Al2O3 dielectric liner used in the ICP plasma source as is well known. The gradual decrease in C concentration and the steady increase in N content were also observed at higher substrate temperatures, as shown in Table V and Figure 10 and 11 as shown.

[0114] These trends are consistent with the observation that the combination of reduced substrate thermal budget and soft remote plasma provides the optimal low-energy environment for the alkyl groups to undergo a gradual and controlled dissociation reaction from the parent molecule; the increase in substrate temperature provides increased thermal activation energy for a higher degree of bond dissociation and redistribution of Si, C, and N bonds within the SiC x N y film.

[0115] Si 2p, N 1s, C 1s, and O 1s binding energies versus penetration depth in SiC x N y high-resolution XPS core-level spectra for samples deposited at 50 and 150 °C, respectively, as shown in Figure 12 and 13 Based on the XPS analysis, the positions of the Si, N, C, and O core-level peaks appear to be independent of the film composition and process thermal budget. More specifically, within the 30 to 150 °C substrate temperature window investigated, the C 1s peak position at ~283.3 eV is attributed to the C-Si bond, and the N 1s peak position at ~397.3 eV is attributed to the N-Si bond, independent of the substrate temperature used. Meanwhile, the Si 2p peak is composed of contributions from the Si-C bond at ~100.4 eV and the Si-N bond at ~101.7 eV, with a negligible contribution from the Si-O bond at 103 eV.

[0116] The high-resolution XPS analysis appears to indicate that for substrate temperatures < 150 °C, the SiC x N y films are primarily composed of simple cross-linked Si-C and Si-N bonds. At 200 °C, no C was observed in the film within the XPS detection limit, and the Si 2p and N 1s peaks correspond to a SiN phase.

[0117] This result is in stark contrast to the previously described films. In the latter, it was reported that the C 1 s peak in SiCxNyexperiences a shift from C-C to C-Si to C-N type bonding as the substrate temperature is increased, while the N 1 s peak exhibits a shift from N-C to predominantly N-Si bonding, with partial contribution from N-C type bonding. At the same time, it was reported that the Si 2p evolves from Si-N, Si-O, and Si-C type bonding to predominantly Si-Si bonding, along with Si-N and Si-C bonds. These results were attributed to the presence of various temperature-dependent complex bonding configurations in the a-SiCN thin films, as described by various researchers in many other reports. x N y The presence of various temperature-dependent complex bonding configurations in the thin films. Unlike the previously reported thin films, the SiC x N y films of the present invention exhibit simple Si-C and Si-N bonds, bonding configurations, or chemical structures that do not change with temperature, providing stable and consistent SiC x N y matrix.

[0118] The results described and demonstrated herein are different from the previous findings in the literature, for example, from atmospheric pressure plasma CVD (AP-PECVD) of (triethylsilane HSiEt3, TES) and N2as Si, C, and N sources. In the latter, it was reported that the C 1 s peak indicates evolution from C-C to C-Si to C-N type bonding, while the N 1 s peak exhibits a shift from N-C to predominantly N-Si bonding, with partial contribution from N-C type bonding. At the same time, it was reported that the Si 2p evolves from Si-N, Si-O, and Si-C type bonding to predominantly Si-Si bonding, along with Si-N and Si-C bonds. These results were attributed to the presence of various temperature-dependent complex bonding configurations in the a-SiCN thin films, as described by various researchers in many other reports.

[0119] Therefore, the XPS analysis supports the judgment that the application of soft remote plasma in pulsed mode is consistent with a reduced substrate thermal budget, where the N-alkyl substituted perhydrocyclotrisilazane precursor and NH3co-reactant only react on the substrate surface, indeed produces: (i) SiC x N y matrix; (ii) a gradual and controlled decrease in C content as the substrate temperature is increased.

[0120] Ellipsometric analysis

[0121] adsorption and reaction pathways of the TICZ source precursor and NH3remote plasma and the resulting SiC x N yIn-situ real-time ellipsometric studies of the thin film nucleation and growth curves were performed to determine the nature and characteristics of the pulsed deposition process. To this end, Figure 14 The SiC x N y film thickness as a function of deposition time for TICZ pulse times of 0.1, 0.2, 0.4 and 0.8 s. In all runs, the substrate temperature was kept at 150 °C. The data show that the film thickness exhibits a steady upward trend with increasing TICZ pulse duration and does not reach a plateau as expected in an ALD process. It should be noted that this trend is observed throughout the entire substrate temperature window investigated, which indicates that the pulsed deposition of SiC x N y indeed occurs in a P-CVD rather than an ALD regime. One advantage of the plasma pulse mode is that partial decomposition of the parent TICZ precursor can occur upon adsorption to the substrate surface and prior to reaction with NH3, a feature that facilitates thin film deposition in a lower thermal budget window.

[0122] Similarly, Figure 15 In-situ, real-time, angle-resolved ellipsometric measurements of the film thickness as a function of deposition time at substrate temperatures of 30, 60, 90, 120, 150 and 170 °C were provided. The plot shows that the thin film nucleation and growth occurs instantaneously, as indicated by the immediate increase in film thickness within the first deposition cycle. This feature is important as it indicates that there is no incubation period prior to the onset of SiC x N y film formation as reported in the literature for other ALD and P-CVD works. From a manufacturing point of view, the absence of such an incubation period makes the plasma-pulsed SiC x N y more attractive by eliminating ex-situ or in-situ pre-deposition substrate surface treatments, thereby reducing the number of process steps required to grow SiC x N y films.

[0123] Furthermore, Figure 15 The plot shows that the slope of the film thickness curve decreases gradually, thus the SiC x N yThe growth rate gradually decreases with increasing substrate temperature. The decrease in GPC at higher substrate temperature can be caused by: (i) a decrease in the partial vapor pressure of the TICZ close to the substrate due to the geometry of the reactor, which leads to an increasing decomposition of the precursors before they enter the chamber and reach the substrate, and / or (ii) a higher desorption rate of the precursors and related moieties from the substrate surface before the NH3co-reactant step due to the increase in the thermal budget. Finally, ex-situ ellipsometry measurements on the thin films deposited at 50, 150 and 200 °C gave a refractive index of ~1.49, ~1.51 and ~1.80, respectively.

[0124] Wet etching rate

[0125] The wet etching rate (WER) was investigated for the thin films grown at 50, 150 and 200 °C and values of 2310, 732 and 99 nm / min were obtained, respectively.

[0126] Those skilled in the art will appreciate that modifications can be made to the above described embodiments without departing from the overall scope of the inventive concept thereof. Accordingly, it is intended to be covered by the appended claims when they are interpreted in their fullest and broadest manner.

Claims

1. A method for depositing a silicon nitride film onto a substrate in a reaction zone of a deposition chamber, said method comprising, in a single cycle: selecting a precursor comprising an N-alkyl substituted perhydridocyclotrisilazane containing at least two carbon atoms per nitrogen atom; heating the substrate to a temperature of 200°C to 650°C; maintaining the substrate at 200°C to 650°C; providing the precursor comprising a gas phase with a carrier gas and / or under vacuum to the reaction zone containing said substrate; wherein the precursor undergoes physisorption and partial decomposition, the partial decomposition comprising removal of at least one ligand from the precursor upon contact with the substrate, but does not result in complete dissociation of the precursor; forming a monolayer of the partially decomposed N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, the monolayer of the partially decomposed N-alkyl substituted perhydridocyclotrisilazane being adsorbed to the substrate surface by physisorption; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a nitrogen containing reactant, a single plasma activation process being performed in each deposition cycle; wherein the adsorbed monolayer of the partially decomposed N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted into a discrete atomic or molecular layer of the silicon nitride film by dissociation and / or decomposition induced by the substrate surface selected from the group consisting of energy transfer, remote plasma application, direct plasma application, oxidation and / or reduction; wherein growth of the discrete atomic or molecular layer of the silicon nitride film occurs during the single cycle without any incubation period; and removing the conversion by-products from the reaction zone by a purging step using an inert gas and / or vacuum.

2. The method of claim 1, further comprising, after forming the monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, removing unreacted N-alkyl substituted perhydridocyclotrisilazane and by-products thereof from the reaction zone by a second purging step using an inert gas and / or vacuum.

3. The method of claim 1, wherein, the temperature of said substrate is 200°C to 350°C.

4. The method of claim 1, wherein, said N-alkyl substituted perhydridocyclotrisilazane is 1,3,5-tris(isopropyl)cyclotrisilazane.

5. The method of claim 1, wherein, said nitrogen containing reactant comprises NH3, N2, a mixture of N2 and H2, methylamine and / or hydrazine.

6. The method of claim 1, wherein, said single cycle is repeated until a film of a predetermined thickness is obtained.

7. A method for depositing a silicon oxide film onto a substrate in a reaction zone of a deposition chamber, said method comprising, in a single cycle: heating the substrate to a temperature of 200°C to 650°C; maintaining the substrate at 200°C to 650°C; providing a precursor of an N-alkyl substituted perhydridocyclotrisilazane comprising a gas phase with a carrier gas and / or under vacuum to the reaction zone containing said substrate; forming a monolayer of the N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of an oxygen containing reactant; wherein the adsorbed monolayer of N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted to discrete atomic or molecular layers of silicon oxide film by dissociation and / or decomposition induced by a substrate surface induced method; and byproducts of the conversion are removed from the reaction zone using an inert gas purge step and / or vacuum.

8. The method of claim 7, wherein, further comprising, after forming the monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, a second purge step from the reaction zone using an inert gas and / or vacuum to remove unreacted N-alkyl substituted perhydridocyclotrisilazane and byproducts thereof.

9. The method of claim 7, wherein, the temperature of the substrate is from 200 °C to 350 °C.

10. The method of claim 7, wherein, the N-alkyl substituted perhydridocyclotrisilazane is 1,3,5-tri(isopropyl)cyclotrisilazane.

11. The method of claim 7, wherein, the nitrogen containing reactant comprises NH3, N2, a mixture of N2 and H2, methylamine and / or hydrazine.

12. The method of claim 7, wherein, the single cycle is repeated until a film of a predetermined thickness is obtained.

13. The method of claim 7, wherein, the substrate surface induced method is energy transfer, remote plasma application, direct plasma application, oxidation, and / or reduction.

14. A method for depositing a silicon carbonitride film onto a substrate in a reaction zone of a deposition chamber, the method comprising, in a single cycle: heating the substrate to a temperature of from room temperature to 200 °C; maintaining the substrate at a temperature of from room temperature to 200 °C; providing a precursor comprising a gas phase of N-alkyl substituted perhydridocyclotrisilazane to the reaction zone containing the substrate with a carrier gas and / or under vacuum; forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a nitrogen containing reactant; wherein the adsorbed monolayer of N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted to discrete atomic or molecular layers of silicon carbonitride film by dissociation and / or decomposition induced by a substrate surface induced method; and byproducts of the conversion are removed from the reaction zone using an inert gas purge step and / or vacuum.

15. The method of claim 14, wherein, further comprising, after forming the monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to the substrate surface, a second purge step from the reaction zone using an inert gas and / or vacuum to remove unreacted N-alkyl substituted perhydridocyclotrisilazane and byproducts thereof.

16. The method of claim 14, wherein, the N-alkyl substituted perhydridocyclotrisilazane is 1,3,5-tri(isopropyl)cyclotrisilazane.

17. The method of claim 14, wherein, the nitrogen containing reactant comprises NH3, N2, a mixture of N2 and H2, methylamine and / or hydrazine.

18. The method of claim 14, wherein, the single cycle is repeated until a film of a predetermined thickness is obtained.

19. The method of claim 14, wherein, the substrate surface induced method is energy transfer, remote plasma application, direct plasma application, oxidation, and / or reduction.

20. A method for depositing a silicon film onto a substrate in a reaction zone of a deposition chamber, the method comprising, in a single cycle: heating the substrate to a temperature of from 200 °C to 650 °C; maintaining the substrate at a temperature of from 200 °C to 650 °C; providing a precursor comprising a gas phase of N-alkyl substituted perhydridocyclotrisilazane to the reaction zone containing the substrate with a carrier gas and / or under vacuum; forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to a surface of a substrate; and exposing the adsorbed monolayer on the substrate in the reaction zone to a remote or direct soft plasma of a hydrogen containing reactant; wherein the adsorbed monolayer of N-alkyl substituted perhydridocyclotrisilazane reacts with the soft plasma and is converted to discrete atomic or molecular layers of a silicon thin film by dissociation and / or decomposition induced by the substrate surface; removing the converted byproducts from the reaction zone by inert gas purging steps and / or vacuum.

21. The method of claim 20, wherein, further comprising, after forming a monolayer of N-alkyl substituted perhydridocyclotrisilazane by adsorption to a surface of a substrate, a second purging step from the reaction zone using inert gas and / or vacuum to remove unreacted N-alkyl substituted perhydridocyclotrisilazane and byproducts thereof.

22. The method of claim 20, wherein, the temperature of the substrate is between 200 °C and 350 °C.

23. The method of claim 20, wherein, the N-alkyl substituted perhydridocyclotrisilazane is 1,3,5-tris(isopropyl)cyclotrisilazane.

24. The method of claim 20, wherein, the single cycle is repeated until a thin film of a predetermined thickness is obtained.

25. The method of claim 20, wherein, the substrate surface induced method is energy transfer, remote plasma application, direct plasma application, oxidation, and / or reduction.

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