Ammonia-free deposition of silicon nitride

Abstract

Methods and apparatuses for depositing silicon nitride using an ammonia-free plasma-enhanced atomic layer deposition process involving a halogen-containing silicon precursor at low temperatures are provided.

Description

LAMRP985WO- 11644- 1 WOAMMONIA-FREE DEPOSITION OF SILICON NITRIDE CROSS-REFERENCE(S)

[0001] A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in their entireties and for all purposes.BACKGROUND

[0002] Semiconductor fabrication processes involve various processes which may include deposition of silicon nitride. Silicon nitride can be deposited using a variety of techniques, some of which involve using thermal processes and some of which involve plasma-based processes.

[0003] The background description provided herein is for the purposes of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] One aspect involves a method for processing substrates, the method including: providing a substrate to a process chamber; generating a plasma by igniting a hydrogencontaining gas and an ammonia- free nitrogen-containing gas, whereby the hydrogencontaining gas is introduced at a flow rate of greater than about 1 slm; and exposing the substrate to a halogen-containing silicon precursor to form silicon nitride on a surface of the substrate.

[0005] In various embodiments, the plasma is an inductively coupled plasma.

[0006] In various embodiments, the substrate is heated to a temperature of less than about 450°C.

[0007] In various embodiments, the ammonia- free nitrogen-containing gas is flowed at a flow rate of less than about 5 slm.

[0008] In various embodiments, the halogen-containing silicon precursor includes a chlorine atom.

[0009] In various embodiments, the halogen-containing silicon precursor includes dichlorosilane.

[0010] In various embodiments, the plasma is generated remotely.LAMRP985WO- 11644- 1 WO

[0011] In various embodiments, the plasma is generated upstream of the process chamber.

[0012] In various embodiments, all or substantially all of the radicals of hydrogen in an environment adjacent to the substrate are radicals of hydrogen in the ground state.

[0013] In various embodiments, the silicon nitride is formed by reacting hydrogen radicals with the halogen-containing silicon precursor.

[0014] In various embodiments, the hydrogen-containing gas includes hydrogen gas (H2).

[0015] In various embodiments, generating the plasma and introducing the halogencontaining silicon precursor are performed in temporally separated pulses.

[0016] In various embodiments, the process chamber is set to a chamber pressure of about 3 Torr to about 10 Torr.

[0017] Another aspect involves an apparatus for processing substrates, the apparatus including: one or more process chambers, each process chamber including a chuck; one or more gas inlets into the process chambers and associated flow-control hardware; a remote plasma generator; and

[0018] a controller having at least one processor and a memory, whereby the at least one processor and the memory are communicatively connected with one another, the at least one processor is at least operatively connected with the flow-control hardware, and the memory stores computer-executable instructions for controlling the at least one processor to at least control the flow-control hardware to: cause introduction of a hydrogen-containing gas to the remote plasma generator at a flow rate of at least about 1 slm; cause generation of a plasma by igniting the hydrogen-containing gas and an ammonia-free nitrogen-containing gas; and cause introduction of a halogen-containing silicon precursor to the one or more process chambers to form silicon nitride.

[0019] These and other aspects are described further below with reference to the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a process flow diagram depicting operations that may be performed in accordance with certain disclosed embodiments.

[0021] Figure 2 illustrates a schematic diagram of an example plasma processing apparatus with a remote plasma source according to some implementations.

[0022] Figure 3 illustrates a schematic diagram of an example plasma processing apparatus with a remote plasma source according to some other implementations.

[0023] Figure 4 is a graph showing density of various silicon nitride films.LAMRP985WO- 11644- 1 WODETAILED DESCRIPTION

[0024] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0025] In the present disclosure, the terms “semiconductor wafer,” “wafer,” “substrate,” “wafer substrate,” and “partially fabricated integrated circuit” are used interchangeably. One of ordinary skill in the art would understand that the term “partially fabricated integrated circuit” can refer to a silicon wafer during any of many stages of integrated circuit fabrication. A wafer or substrate used in the semiconductor device industry typically has a diameter of 200 mm, or 300 mm, or 450 mm. The following detailed description assumes the present disclosure is implemented on a wafer. However, the present disclosure is not so limited. The work piece may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other work pieces that may take advantage of the present disclosure include various articles such as printed circuit boards and the like.

[0026] Semiconductor processing may involve deposition of one or more layers of film onto a substrate. Examples of deposition techniques may include but are not limited to PVD, CVD, PECVD, ALD, and PEALD. CVD processes may deposit a film on a substrate surface by flowing one or more gas reactants into a reaction chamber which form film precursors and byproducts. The precursors are transported to the substrate surface where they are adsorbed by the substrate and deposited on the substrate by gas phase chemical reactions. ALD is a deposition technique that involves multiple film deposition cycles. ALD deposits thin layers of material using sequential self-limiting reactions. Typically, an ALD cycle includes operations to deliver and adsorb at least one precursor to the substrate surface, and then react the adsorbed precursor with one or more reactants to form the partial layer of film. Purge steps are ordinarily carried out between delivery of the precursor and delivery of the one or more reactants. Multiple ALD cycles are carried out to build up a film to a desired thickness.

[0027] PEALD and PECVD uses plasma to promote reaction between adsorbed precursor and reactant radicals. When plasma is ignited, ions and / or radicals of reactant gases may be generated to react with adsorbed precursors on the substrate. In PECVD, reactant gases mayLAMRP985WO- 11644- 1 WObe continuously delivered to the substrate while the substrate is exposed to plasma. In PEALD, reactant gases are activated and the substrate is exposed to plasma during a conversion / reaction phase of an ALD cycle.

[0028] Silicon-containing films may be deposited by a vapor deposition technique such as CVD, PECVD, ALD, or PEALD. Silicon-containing films have various physical, chemical, electrical, and mechanical properties and are often used in semiconductor fabrication processes. For example, silicon nitride, silicon oxide, or silicon oxynitride films may be used as diffusion barriers, gate insulators, sidewall spacers, etch stop layers, dielectric films, and encapsulation layers. For example, conformal silicon nitride layers may be used in fabrication of memory structures. Conformal silicon nitride layers may be utilized in 3D memory structures such as vertical NAND flash memory structures that may employ high aspect ratios. Silicon nitride layers may be deposited with high conformality, low wet etch rate (WER) and / or low dry etch rate (DER), and high density, among other material properties.

[0029] Silicon-containing films such as silicon oxides, silicon nitrides, silicon carbides, silicon oxynitrides, silicon carbonitrides, silicon oxycarbides, and / or silicon oxycarbonitrides with desired properties may be obtained with the assistance of plasma and high operating temperatures in a suitable semiconductor processing apparatus. Plasma-assisted processes may speed up deposition rates and enable improved film properties (e.g., density). High temperatures may also accelerate deposition rates by shortening reaction completion times. Furthermore, certain chemical reactions may not take place unless the operating temperature is sufficiently high. Though some precursors may decompose at exceedingly high temperatures, other precursors may be selected for their ability to avoid decomposition and perform certain chemical reactions at such high temperatures.

[0030] It will be understood that the vapor deposition techniques of the present disclosure are not limited to silicon-containing films, but may be used to deposit other types of films such as nitrides, oxides, and oxynitrides.

[0031] Silicon nitride can be deposited using particular silicon-containing precursors. “Silicon nitride” is referred to herein as including any and all stoichiometric possibilities for SixNy, including integer values of x and y and non-integer values of x and y, such as x=3 and y-4. For example, “silicon nitride” includes compounds having the formula SiNn, where 1 < n < 2, where n can be an integer or non-integer values. “Silicon nitride” can include sub-stoichiometric compounds such as SiN1.8. “Silicon nitride” also includes Si3N4 and silicon nitride with trace and / or interstitial hydrogen (SiNH) and silicon nitride with trace amounts ofLAMRP985WO- 11644- 1 WOand / or interstitial oxygen (SiON). “Silicon nitride” also includes both natural and synthetic variations and also includes any and all lattice, crystalline, and molecular structures, including trigonal alpha-silicon nitride, hexagonal beta-silicon nitride, and cubic gamma-silicon nitride. “Silicon nitride” also includes amorphous silicon nitride and can include silicon nitride having trace amounts of impurities.

[0032] In the past, dichlorosilane was used but it could only be used at higher temperatures, such as greater than about 500°C or greater than about 650°C or greater than about 800°C. As lower temperature processes were developed, selection of the silicon-containing precursor for depositing silicon nitride shifted to using a different precursor, such as silicon iodide, particularly for applications at or about 200°C to about 450°C. However, as technology develops, the lower temperature regime may not be as critical for certain applications, so there is a shift to using other silicon-containing precursors that are cheaper than silicon iodide.

[0033] Provided herein are methods and apparatuses for depositing silicon nitride at low temperatures in an ammonia- free process using a silicon-containing precursor that is capable of being reactive with ammonia. One class of silicon-containing precursors that is capable of being reactive with ammonia that may be used for certain disclosed embodiments include halogen-containing silicon precursors. One class of silicon-containing precursors that is capable of being reactive with ammonia that may be used for certain disclosed embodiments include chlorine-containing silicon precursors. One example of a chlorine-containing silicon precursor that may be used in certain disclosed embodiments is dichlorosilane.

[0034] While this disclosure is not limited by any particular theory, it is believed that as more hydrogen is incorporated into the film, the hydrogen atoms disrupt the bonding of the film, resulting in a lower quality film which can be measured by its density. However, as hydrogen flow rate during deposition increases, at a certain point, the film quality surprisingly improved. Further, there were surprising results that such deposition process can also be performed ammonia- free. Advantages of having an ammonia- free process include but are not limited to reducing and / or eliminating cleaning physisorbed ammonia from components on the processing chamber, which can be difficult to do, and / or eliminating having to purge between exposures to the silicon-containing precursor and the ammonia.

[0035] Certain disclosed embodiments involve generating a plasma species using a hydrogen-containing gas, such as but not limited to hydrogen gas (H2) without ammonia, and introducing a halogen-containing silicon precursor, also without ammonia, to form silicon nitride. The generation of the plasma species is performed using process conditions that mimicLAMRP985WO- 11644- 1 WOthe species that may be generated when ammonia is ignited, but without using ammonia. For example, the hydrogen gas is flowed at a much higher flow rate, such as greater than about 1000 seem. Certain disclosed embodiments involve using plasma species that have radicals, including hydrogen radicals.

[0036] Figure 1 shows an example process flow diagram of operations that may be performed in accordance with certain disclosed embodiments. Operations 104 and 106 may be performed in any order. In operation 102, a substrate is provided to a process chamber. The substrate 100 can be any wafer, semiconductor wafer, partially fabricated integrated circuit, printed circuit board, display screen, or other appropriate work piece. The substrate may be a silicon wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semi-conducting material deposited thereon. In various embodiments, the substrate is patterned.

[0037] In operation 104, a plasma is generated in a plasma-generating region, such as in a remote plasma generator, using an ammonia-free nitrogen-containing gas and hydrogencontaining gas introduced at a high flow rate, such as greater than about 1 slm, or greater than about 4 slm, or between about 4 slm and about 5 slm.

[0038] The ammonia-free nitrogen-containing gas may be nitrogen gas (N2). The ammonia-free nitrogen-containing gas is flowed at a flow rate dependent on the flow rate of the hydrogencontaining gas and the application. In some embodiments, the ammonia-free nitrogencontaining gas is flowed at a flow rate of less than about 5 slm for a single-station processing chamber, or at least about 15 slm to about 20 slm for a quad- station chamber.

[0039] In various embodiments, the ratio of flow rate of hydrogen-containing gas to ammonia-free nitrogen-containing gas may be about 1:5 to about 1:20 or greater.

[0040] The plasma may generate radical species, which may be delivered to a processing region over the substrate. In some embodiments, the plasma is filtered through an ion filter or showerhead such that the species that flow to the processing region from the plasma-generating region are substantially low energy state radicals.

[0041] In addition to silicon-containing precursors, the environment adjacent the work piece (e.g., the substrate) can include one or more radical species, preferably in a substantially low energy state. An example of such species includes hydrogen radicals (i.e., hydrogen atom radicals). In some embodiments, all, or substantially all, or a substantial fraction of the hydrogen atom radicals can be in the ground state, e.g., at least about 90% or 95% of the hydrogen atom radicals adjacent the work piece are in the ground state. In certainLAMRP985WO- 11644- 1 WOembodiments, source gas is provided in a carrier gas such as helium. As an example, hydrogen gas may be provided in a helium carrier at a concentration of about 1-10% hydrogen. Pressure, fraction of carrier gas such as helium, and other process conditions are chosen so that the hydrogen atoms encounter the substrate as radicals in a low energy state without recombining.

[0042] As explained elsewhere, hydrogen gas may be supplied into a remote plasma source to generate hydrogen atom radicals. The remote plasma source may be positioned upstream from the substrate surface and the environment adjacent to the substrate surface. Once generated, the hydrogen atom radicals may be in an excited energy state. For example, hydrogen in an excited energy state can have an energy of at least 10.2 eV (first excited state). Excited hydrogen atom radicals may cause unselective decomposition of a silicon-containing precursor. For example, hydrogen atom radicals in an excited state can easily break Si-H, Si-Si, Si-N, Si-O, and Si-C bonds, which can alter the composition or physical or electrical characteristics of the silicon nitride film. In some implementations, when the excited hydrogen atom radicals lose their energy, or relax, the excited hydrogen atom radical may become a substantially low energy state hydrogen atom radical or a ground state hydrogen atom radical. Hydrogen atom radicals in a substantially low energy state or ground state can be capable of selectively breaking Si-H and Si-Si bonds while generally preserving Si-O, Si-N, and Si-C bonds. In some implementations, process conditions may be provided so that excited hydrogen atom radicals lose energy or relax to form substantially low energy state or ground state hydrogen atom radicals. For example, the remote plasma source or associated components may be designed so that a residence time of hydrogen atom radicals diffusing from the remote plasma source to the substrate is greater than the energetic relaxation time of an excited hydrogen atom radical. The energetic relaxation time for an excited hydrogen atom radical can be about equal to or less than about 1x1 O’3seconds.

[0043] A state in which a substantial fraction of hydrogen atom radicals are in the ground state can be achieved by various techniques. Some apparatuses, such as described below, are designed to achieve this state. Apparatus features and process control features can be tested and tuned to produce a mild state in which a substantial fraction of the hydrogen atom radicals are in the ground state. For example, an apparatus may be operated and tested for charged particles downstream of the plasma source; i.e., near the substrate. The process and apparatus may be tuned until substantially no charged species exist near the substrate. Additionally, apparatus and process features may be tuned to a configuration where they begin to produce a silicon nitride film from a standard silicon-containing precursor. The relatively mild conditionsLAMRP985WO- 11644- 1 WOthat support such film deposition are chosen.

[0044] In some embodiments, the process conditions employ radical species in a substantially low energy state sufficient to break Si-H bonds and / or Si-Si bonds while substantially preserving Si-O, Si-N, and Si-C bonds. Such process conditions may not have substantial amounts of ions, electrons, or radical species in high energy states such as states above the ground state. In some embodiments, the concentration of ions in the region adjacent the film is no greater than about 107 / cm3. The presence of substantial amounts of ions or high energy radicals may tend to break Si-O, Si-N, and Si-C bonds, which can produce films with undesirable electrical properties (e.g., high dielectric constants and / or low breakdown voltages) and poor conformality. It is believed that an excessively reactive environment produces reactive precursor fragments that have high sticking coefficients (representing a propensity to chemically or physically stick to work piece sidewalls), resulting in poor conformality.

[0045] The silicon-containing precursors are typically delivered with other species, notably carrier gas, in the environment adjacent to the substrate. In some implementations, the silicon-containing precursors are present with the radical species and other species, including other reactive species and / or carrier gases. In some embodiments, the silicon-containing precursors may be introduced as a mixture. Upstream from the deposition reaction surface, the silicon-containing precursors can be mixed with an inert carrier gas. Example inert carrier gases include, but are not limited to, argon (Ar) and helium (He). In addition, the silicon-containing precursors can be introduced in a mixture having major and minor species, with the minor species containing some element or structural feature (e.g., a ring structure, a cage structure, an unsaturated bond, etc.) that is present in the silicon nitride film at a relatively low concentration. It will be understood, however, that the minor species may not significantly contribute to the composition or structural feature of the silicon nitride film. The multiple precursors may be present in equimolar or relatively similar proportions as appropriate to form the primary backbone or matrix in the resulting silicon nitride film. In other embodiments, the relative amounts of the different precursors are substantially skewed from equimolarity.

[0046] In some embodiments, one or more silicon-containing precursors provide essentially all of the mass of the deposited silicon nitride film, with small amounts of hydrogen or other element from a remote plasma providing less than about 5% atomic or less than about 2% atomic of the film mass. In some embodiments, only the radical species and the one or more silicon-containing precursors contribute to the composition of the deposited silicon nitride film.

[0047] While certain examples described herein involve generating the plasma using aLAMRP985WO- 11644- 1 WOremote plasma, in some embodiments, it will be understood that an in-situ plasma may be used. In some embodiments, purging is performed between operations 104 and 106. In some embodiments, purging is not performed between operations 104 and 106. In some embodiments, the duration upon which operations 104 and 106 are being performed may overlap; for example, in some embodiments, operations 104 and 106 may be performed simultaneously without a time break between them.

[0048] Returning to Figure 1, in operation 106, a halogen-containing silicon precursor is introduced to the process chamber. The halogen-containing silicon precursor may include chlorine. The halogen-containing silicon precursor may be dichlorosilane. The halogencontaining silicon precursor reacts with the radicals to form silicon nitride on the substrate.

[0049] The temperature in the environment adjacent to the substrate can be any suitable temperature facilitating the deposition reaction, but sometimes limited by the application of the device containing the silicon nitride film. In some embodiments, the temperature in the environment adjacent to the substrate can be largely controlled by the temperature of a pedestal on which a substrate is supported during deposition of the silicon nitride film. In some embodiments, the operating temperature can be between about 50°C and about 600°C. For example, the operating temperature can be between about 250°C and about 400°C or about 250°C to about 550°C, or about 450°C to about 550°C in many integrated circuit applications. In some embodiments, increasing the temperature can lead to increased cross-linking on the substrate surface.

[0050] The pressure in the environment adjacent to the substrate can be any suitable pressure to produce reactive radicals in a reaction chamber. In some embodiments, the pressure can be about 35 Torr or lower. For example, the pressure can be between about 10 Torr and about 20 Torr, such as in embodiments implementing a microwave generated plasma. In other examples, the pressure can be less than about 5 Torr, or between about 0.2 Torr and about 5 Torr, such as in embodiments implementing a radio-frequency (RF) generated plasma.

[0051] The environment adjacent to the substrate provides for deposition of the silicon nitride film on the substrate by remote plasma CVD. A source gas is supplied to a remote plasma source, and power is provided to the remote plasma source that may cause the source gas to dissociate and generate ions and radicals in an excited energy state. After excitation, the radicals in the excited energy state relax to substantially low energy state radicals or ground state radicals, such as ground state hydrogen radicals. Bonds in the silicon-containing precursor may be selectively broken by the hydrogen radicals in a relaxed energy state. The plasma mayLAMRP985WO- 11644- 1 WObe generated using a radio frequency plasma having a power of about 1 kW to about 10 kW or about 1 kW to about 6kW for a quad-station chamber.

[0052] Certain disclosed embodiments form silicon nitride films at a growth rate of greater than about 0.7 A / cycle. Certain disclosed embodiments form silicon nitride films having a density of greater than about 2.8 g / cm3. Certain disclosed embodiments form silicon nitride films having a wet etch rate in 100:1 diluted HF of at least about 3.2 A / min.Chemical Structure of Precursors

[0053] As discussed, the precursors employed in forming silicon nitride films using certain disclosed embodiments can include halogen-containing silicon-containing precursors, with at least some of the silicon-containing precursors having at least one Si-H and / or at least one Si-Si bond. In certain embodiments, the silicon-containing precursor has at most one hydrogen atom on every silicon atom. Thus, for example, a precursor having one silicon atom has at most one hydrogen atom bonded to the silicon atom; a precursor having two silicon atoms has one hydrogen atom bonded to one silicon atom and optionally another hydrogen atom bonded to the second silicon atom; a precursor having three silicon atoms has at least one hydrogen atom bonded to one silicon atom and optionally one or two more hydrogen atoms bonded to one or two of the remaining silicon atoms, and so on. However, in some implementations, the silicon-containing precursor has two or more hydrogen atoms bonded on a silicon atom or on every silicon atom. In addition, the silicon-containing precursors may include at least one Si-O bond, at least one Si-N bond, and / or at least one Si-C bond. While any number of appropriate precursors can be used in forming silicon nitride films, at least some of the precursors will include silicon-containing precursors with at least one Si-H bond or Si- Si bond, and optionally at least one Si-0 bond, Si-N bond, and / or Si-C bond. In various implementations, the silicon-containing precursor(s) contain no O-C or N-C bonds; e.g., the precursor(s) contain no alkoxy (-O-R), where R is an organic group such as a hydrocarbon group, or amine (-NR1R2) groups, wherein Ri and R2 are independently hydrogen or organic groups. It is believed that such groups may impart high sticking coefficients to the precursors or fragments on which they reside.

[0054] A halogen-containing silicon precursor may be a halosilane, which includes at least one halogen group and may or may not include hydrogens and / or carbon groups. Examples of halosilanes are iodosilanes, bromosilanes, chlorosilanes and fluorosilanes. Although halosilanes, particularly fluorosilanes, may form reactive halide species that can etch silicon materials when a plasma is struck, a halosilane may not be introduced to the chamber when aLAMRP985WO- 11644- 1 WOplasma is struck in some embodiments, so formation of a reactive halide species from a halosilane may be mitigated. Specific chlorosilanes are tetrachlorosilane, trichlorosilane, dichlorosilane, monochlorosilane, chloroallylsilane, chloromethylsilane, dichloromethylsilane, chlorodimethylsilane, chloroethylsilane, t-butylchlorosilane, di-t-butylchlorosilane, chloroisopropylsilane, chloro-sec-butylsilane, t-butyldimethylchlorosilane, thexyldimethylchlorosilane, and the like.APPARATUS

[0055] One aspect of the disclosure is an apparatus configured to accomplish the methods described herein. A suitable apparatus includes hardware for accomplishing the process operations and a system controller having instructions for controlling process operations in accordance with the present disclosure. In some embodiments, the apparatus for performing the aforementioned process operations can include a remote plasma source. A remote plasma source provides mild reaction conditions in comparison to a direct plasma. An example of a suitable remote plasma apparatus is described in U.S. Patent Application No. 14 / 062,648, filed October 24, 2013, which is incorporated herein by reference in its entirety and for all purposes.

[0056] Figure 2 presents a schematic diagram of a remote plasma apparatus according to certain embodiments. The device 200 includes a reaction chamber 210 with a showerhead 220. Inside the reaction chamber 210, a substrate 230 rests on a stage or pedestal 235. In some embodiments, the pedestal 235 can be fitted with a heating / cooling element. A controller 240 may be connected to the components of the device 200 to control the operation of the device 200. For example, the controller 240 may contain instructions for controlling process conditions for the operations of the device 200, such as the temperature process conditions and / or the pressure process conditions. In some embodiments, the controller 240 may contain instructions for controlling the flow rates of precursor gas, ammonia-free nitrogen-containing gas, hydrogen-containing and carrier gas. The controller 240 may contain instructions for changing the flow rate of one or more gases over time. In addition or in the alternative, the controller 240 may contain instructions for changing the flow rate of the precursor gas over time. A more detailed description of the controller 240 is provided below.

[0057] During operation, gases or gas mixtures are introduced into the reaction chamber 210 via one or more gas inlets coupled to the reaction chamber 210. In some embodiments, two or more gas inlets are coupled to the reaction chamber 210. A first gas inlet 255 can be coupled to the reaction chamber 210 and connected to a vessel 250, and a second gas inlet 265 can be coupled to the reaction chamber 210 and connected to a remote plasma source 260. InLAMRP985WO- 11644- 1 WOembodiments including remote plasma configurations, the delivery lines for the precursors and the radical species generated in the remote plasma source are separated. Hence, the precursors and the radical species do not substantially interact before reaching the substrate 230. It will be understood that in some implementations the gas lines may be reversed so that the vessel 250 may provide precursor gas flow through the second gas inlet 265 and the remote plasma source 260 may provide ions and radicals through the first gas inlet 255.

[0058] One or more radical species may be generated in the remote plasma source 260 and configured to enter the reaction chamber 210 via the second gas inlet 265. Any type of plasma source may be used in remote plasma source 260 to create the radical species. This includes, but is not limited to, capacitively coupled plasmas, inductively coupled plasmas, microwave plasmas, DC plasmas, and laser-created plasmas. An example of a capacitively coupled plasma can be a radio frequency (RF) plasma. A high-frequency plasma can be configured to operate at 13.56 MHz or higher. An example of such a remote plasma source 260 can be the GAMMA®, manufactured by Lam Research Corporation of Fremont, California. Another example of such a RF remote plasma source 260 can be the Astron®, manufactured by MKS Instruments of Wilmington, Massachusetts, which can be operated at 440 kHz and can be provided as a subunit bolted onto a larger apparatus for processing one or more substrates in parallel. In some embodiments, a microwave plasma can be used as the remote plasma source 260, such as the Astex®, also manufactured by MKS Instruments. A microwave plasma can be configured to operate at a frequency of 2.45 GHz. Gas provided to the remote plasma source may include hydrogen, nitrogen, oxygen, and other gases as mentioned elsewhere herein. In certain embodiments, hydrogen is provided in a carrier gas such helium. As an example, hydrogen gas may be provided in a helium carrier at a concentration of about 1-10% hydrogen.

[0059] The precursors can be provided in vessel 250 and can be supplied to the showerhead 220 via the first gas inlet 255. The showerhead 220 distributes the precursors into the reaction chamber 210 toward the substrate 230. The substrate 230 can be located beneath the showerhead 220. It will be appreciated that the showerhead 220 can have any suitable shape, and may have any number and arrangement of ports for distributing gases to the substrate 230. The precursors can be supplied to the showerhead 220 and ultimately to the substrate 230 at a controlled flow rate.

[0060] The one or more radical species formed in the remote plasma source 260 can be carried in the gas phase toward the substrate 230. The one or more radical species can flow through a second gas inlet 265 into the reaction chamber 210. It will be understood that theLAMRP985WO- 11644- 1 WOsecond gas inlet 265 need not be transverse to the surface of the substrate 230 as illustrated in Figure 2. In certain embodiments, the second gas inlet 265 can be directly above the substrate 230 or in other locations. The distance between the remote plasma source 260 and the reaction chamber 210 can be configured to provide mild reactive conditions such that the ionized species generated in the remote plasma source 260 are substantially neutralized, but at least some radical species in substantially low energy states remain in the environment adjacent to the substrate 230. Such low energy state radical species are not recombined to form stable compounds. The distance between the remote plasma source 260 and the reaction chamber 210 can be a function of the aggressiveness of the plasma (e.g., determined in part by the source RF power level), the density of gas in the plasma (e.g., if there’s a high concentration of hydrogen atoms, a significant fraction of them may recombine to form H2 before reaching the reaction chamber 210), and other factors. In some embodiments, the distance between the remote plasma source 260 and the reaction chamber 210 can be between about 1 cm and 30 cm, such as about 5 cm or about 15 cm.

[0061] In some embodiments, a co-reactant, which is not the primary silicon-containing precursor or a hydrogen radical, is introduced during the deposition reaction. In some implementations, the apparatus is configured to introduce the co-reactant through the second gas inlet 265, in which case the co-reactant is at least partially converted to plasma. In some implementations, the apparatus is configured to introduce the co-reactant through the showerhead 220 via the first gas inlet 255. Examples of the co-reactant include oxygen, nitrogen, ammonia, carbon dioxide, carbon monoxide, and the like. The flow rate of the coreactant can vary over time to produce a composition gradient in a graded film.

[0062] Figure 3 illustrates a schematic diagram of an example plasma processing apparatus with a remote plasma source according to some other implementations. The plasma processing apparatus 300 includes the remote plasma source 302 separated from a reaction chamber 304. The remote plasma source 302 is fluidly coupled with the reaction chamber 304 via a multiport gas distributor 306, which may also be referred to as a showerhead. Radical species are generated in the remote plasma source 302 and supplied to the reaction chamber 304. One or more silicon-containing precursors are supplied to the reaction chamber 304 downstream from the remote plasma source 302 and from the multiport gas distributor 306. The one or more silicon-containing precursors react with the radical species in a chemical vapor deposition zone 308 of the reaction chamber 304 to deposit a silicon nitride film on a surface of a substrate 312. The chemical vapor deposition zone 308 includes an environment adjacent to the surface of theLAMRP985WO- 11644- 1 WOsubstrate 312.

[0063] The substrate 312 is supported on a substrate support or pedestal 314. The pedestal 314 may move within the reaction chamber 304 to position the substrate 312 within the chemical vapor deposition zone 308. In the embodiment shown in Figure 3, pedestal 314 is shown having elevated the substrate 310 within the chemical vapor deposition zone 308. The pedestal 314 may also adjust the temperature of the substrate 312 in some embodiments, which can provide some selective control over thermally activated surface reactions on the substrate 312.

[0064] Figure 3 shows a coil 318 arranged around the remote plasma source 302, where the remote plasma source 302 includes an outer wall (e.g., quartz dome). The coil 318 is electrically coupled to a plasma generator controller 322, which may be used to form and sustain plasma within a plasma region 324 via inductively coupled plasma generation. In some implementations, the plasma generator controller 322 may include a power supply for supplying power to the coil 318, where the power can be in a range between about 1 and 6 kilowatts (kW) during plasma generation. In some implementations, electrodes or antenna for parallel plate or capacitively coupled plasma generation may be used to generate a continuous supply of radicals via plasma excitation rather than inductively coupled plasma generation. Regardless of the mechanism used to ignite and sustain the plasma in the plasma region 324, radical species may continuously be generated using plasma excitation during film deposition. In some implementations, hydrogen radicals are generated under approximately steady-state conditions during steady-state film deposition, though transients may occur at the beginning and end of film deposition.

[0065] A supply of hydrogen radicals may be continuously generated within the plasma region 324 while hydrogen gas or other source gas is being supplied to the remote plasma source 302. Excited hydrogen radicals may be generated in the remote plasma source 302. If not re-excited or re-supplied with energy, or re-combined with other radicals, the excited hydrogen radicals lose their energy, or relax. Thus, excited hydrogen radicals may relax to form hydrogen radicals in a substantially low energy state or ground state.

[0066] The hydrogen gas or other source gas may be diluted with one or more additional gases. These one or more additional gases may be supplied to the remote plasma source 302. In some implementations, the hydrogen gas or other source gas is mixed with one or more additional gases to form a gas mixture, where the one or more additional gases can include a carrier gas. Non-limiting examples of additional gases can include helium (He), neon (Ne),LAMRP985WO- 11644- 1 WOargon (Ar), krypton (Kr), xenon (Xe), and nitrogen (N2). The one or more additional gases may support or stabilize steady-state plasma conditions within the remote plasma source 302 or aid in transient plasma ignition or extinction processes. In some implementations, diluting hydrogen gas or other source gas with helium, for example, may permit higher total pressures without concomitant plasma breakdown. Put another way, a dilute gas mixture of hydrogen gas and helium may permit higher total gas pressure without increasing plasma power to the remote plasma source 302. As shown in Figure 3, a source gas supply 326 is fluidly coupled with the remote plasma source 302 for supplying the hydrogen gas or source gas. In addition, an additional gas supply 328 is fluidly coupled with the remote plasma source 302 for supplying the one or more additional gases. The one or more additional gases may also include a coreactant gas as described above. While the embodiment in Figure 3 depicts the gas mixture of the source gas and the one or more additional gases being introduced through separate gas outlets, it will be understood that the gas mixture may be introduced directly into the remote plasma source 302. That is, a pre-mixed dilute gas mixture may be supplied to the remote plasma source 302 through a single gas outlet.

[0067] Gases, such as excited hydrogen and helium radicals and relaxed gases / radicals, flow out of the remote plasma source 302 and into the reaction chamber 304 via multiport gas distributor 306. Gases within the multiport gas distributor 306 and within the reaction chamber 304 are generally not subject to continued plasma excitation therein. In some implementations, the multiport gas distributor 306 includes an ion filter and / or a photon filter. Filtering ions and / or photons may reduce substrate damage, undesirable re-excitation of molecules, and / or selective breakdown or decomposition of silicon-containing precursors within the reaction chamber 304. Multiport gas distributor 306 may have a plurality of gas ports 334 to diffuse the flow of gases into the reaction chamber 304. In some implementations, the plurality of gas ports 334 may be mutually spaced apart. In some implementations, the plurality of gas ports 334 may be arranged as an array of regularly spaced apart channels or through-holes extending through a plate separating the remote plasma source 302 and the reaction chamber 304. The plurality of gas ports 334 may smoothly disperse and diffuse exiting radicals from the remote plasma source 302 into the reaction chamber 304.

[0068] Typical remote plasma sources are far removed from reaction vessels. Consequently, radical extinction and recombination, e.g., via wall collision events, may reduce active species substantially. In contrast, in some implementations, dimensions for the plurality of gas ports 334 may be configured in view of the mean free path or gas flow residence time under typicalLAMRP985WO- 11644- 1 WOprocessing conditions to aid the free passage of radicals into the reaction chamber 304. In some implementations, openings for the plurality of gas ports 334 may occupy between about 5% and about 20% of an exposed surface area of the multiport gas distributor 306. In some implementations, the plurality of gas ports 334 may each have an axial length to diameter ratio of between about 3:1 and 10:1 or between about 6:1 and about 8:1. Such aspect ratios may reduce wall-collision frequency for radical species passing through the plurality of gas ports 334 while providing sufficient time for a majority of excited state radical species to relax to ground state radical species. In some implementations, dimensions of the plurality of gas ports 334 may be configured so that the residence time of gases passing through the multiport gas distributor 306 is greater than the typical energetic relaxation time of an excited state radical species. Excited state radical species for hydrogen source gas may be denoted by »H* in Figure 3 and ground state radical species for hydrogen source gas may be denoted by *H in Figure 3.

[0069] In some implementations, excited state radical species exiting the plurality of gas ports 334 may flow into a relaxation zone 338 contained within an interior of the reaction chamber 304. The relaxation zone 338 is positioned upstream of the chemical vapor deposition zone 308 but downstream of the multiport gas distributor 306. Substantially all or at least 90% of the excited state radical species exiting the multiport gas distributor 306 will transition into relaxed state radical species in the relaxation zone 338. Put another way, almost all of the excited state radical species (e.g., excited hydrogen radicals) entering the relaxation zone 338 become de-excited or transition into a relaxed state radical species (e.g., ground state hydrogen radicals) before exiting the relaxation zone 338. In some implementations, process conditions or a geometry of the relaxation zone 338 may be configured so that the residence time of radical species flowing through the relaxation zone 338, e.g., a time determined by mean free path and mean molecular velocity, results in relaxed state radical species flowing out of the relaxation zone 338.

[0070] With the delivery of radical species to the relaxation zone 338 from the multiport gas distributor 306, one or more silicon-containing precursors and / or one or more co-reactants may be introduced into the chemical vapor deposition zone 308. The one or more silicon-containing precursors may be introduced via a gas distributor or gas outlet 342, where the gas outlet 342 may be fluidly coupled with a precursor supply source 340. The relaxation zone 338 may be contained within a space between the multiport gas distributor 306 and the gas outlet 342. The gas outlet 342 may include mutually spaced apart openings so that the flow of the one or more silicon-containing precursors may be introduced in a direction parallel with gas mixtureLAMRP985WO- 11644- 1 WOflowing from the relaxation zone 338. The gas outlet 342 may be located downstream from the multiport gas distributor 306 and the relaxation zone 338. The gas outlet 342 may be located upstream from the chemical vapor deposition zone 308 and the substrate 312. The chemical vapor deposition zone 308 is located within the interior of the reaction chamber 304 and between the gas outlet 342 and the substrate 312.

[0071] Substantially all of the flow of the one or more silicon-containing precursors may be prevented from mixing with excited state radical species adjacent to the multiport gas distributor 306. Relaxed or ground state radical species mix in a region adjacent to the substrate 312 with the one or more silicon-containing precursors. The chemical vapor deposition zone 308 includes the region adjacent to the substrate 312 where the relaxed or ground state radical species mix with the one or more silicon-containing precursors. The relaxed or ground state radical species mix with the one or more silicon-containing precursors in the gas phase during CVD formation of a silicon nitride film.

[0072] In some implementations, a co-reactant may be introduced from the gas outlet 342 and flowed along with the one or more silicon-containing precursors. The co-reactant may include a carbon-containing precursor as described below. The co-reactant may be introduced downstream from the remote plasma source 302. The co-reactant may be supplied from the precursor supply source 340 or other source (not shown) fluidly coupled to the gas outlet 342. The co-reactant may be a carbon-containing precursor as described below. In some implementations, a co-reactant may be introduced from the multiport gas distributor 306 and flowed along with the radical species generated in the remote plasma source 302 and into the reaction chamber 304. This may include radicals and / or ions of a co-reactant gas provided in the remote plasma source 302. The co-reactant may be supplied from the additional gas supply 328.

[0073] The gas outlet 342 may be separated from the multiport gas distributor 306 by a sufficient distance to prevent back diffusion or back streaming of the one or more silicon-containing precursors. In some implementations, the gas outlet 342 may be separated from the plurality of gas ports 334 by a distance between about 0.5 inches and about 5 inches, or between about 1.5 inches and about 3.5 inches, or between about 1.5 inches and about 3 inches.

[0074] Process gases may be removed from the reaction chamber 304 via an outlet 348 configured that is fluidly coupled to a pump (not shown). Thus, excess silicon-containing precursors, co-reactants, radical species, and diluent and displacement or purge gases may be removed from the reaction chamber 304. In some implementations, a system controller 350 isLAMRP985WO- 11644- 1 WOin operative communication with the plasma processing apparatus 300. In some implementations, the system controller 350 includes a processor system 352 (e.g., microprocessor) configured to execute instructions held in a data system 354 (e.g., memory). In some implementations, the system controller 350 may be in communication with the plasma generator controller 322 to control plasma parameters and / or conditions. In some implementations, the system controller 350 may be in communication with the pedestal 314 to control pedestal elevation and temperature. In some implementations, the system controller 350 may control other processing conditions, such as RF power settings, frequency settings, duty cycles, pulse times, pressure within the reaction chamber 304, pressure within the remote plasma source 302, gas flow rates from the source gas supply 326 and the additional gas supply 328, gas flow rates from the precursor supply source 340 and other sources, temperature of the pedestal 314, and temperature of the reaction chamber 304, among others.

[0075] Aspects of the controller 350 of Figure 3 described below also apply to the controller 240 of Figure 2. The controller 350 may contain instructions for controlling process conditions for the operation of the plasma processing apparatus 300. The controller 350 will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. Instructions for implementing appropriate control operations are executed on the processor. These instructions may be stored on the memory devices associated with the controller 350 or they may be provided over a network.

[0076] In certain embodiments, the controller 350 controls all or most activities of the plasma processing apparatus 300 described herein. For example, the controller 350 may control all or most activities of the plasma processing apparatus 300 associated with depositing a silicon nitride film and, optionally, other operations in a fabrication flow that includes the silicon nitride film. The controller 350 may execute system control software including sets of instructions for controlling the timing, gas composition, gas flow rates, chamber pressure, chamber temperature, RF power levels, substrate position, and / or other parameters. Other computer programs, scripts, or routines stored on memory devices associated with the controller 350 may be employed in some embodiments. To provide relatively mild reactive conditions at the environment adjacent to the substrate 312, parameters such as the RF power levels, gas flow rates to the plasma region 324, gas flow rates to the chemical vapor deposition zone 308, and timing of the plasma ignition can be adjusted and maintained by controller 350. Additionally, adjusting the substrate position may further reduce the presence of high-energyLAMRP985WO- 11644- 1 WOradical species at the environment adjacent to the substrate 312. In a multi-station reactor, the controller 350 may comprise different or identical instructions for different apparatus stations, thus allowing the apparatus stations to operate either independently or synchronously.

[0077] In some embodiments, the controller 350 may include instructions for performing operations such as flowing one or more silicon-containing precursors through the gas outlet 342 into the reaction chamber 304, providing a source gas into the remote plasma source 302, generating one or more radical species of the source gas in the remote plasma source 302, introducing the one or more radical species in a substantially low energy state from the remote plasma source 302 into the reaction chamber 304 to react with the one or more silicon-containing precursors to deposit a silicon nitride film on the substrate 312. The one or more radical species in the reaction chamber 304 in an environment adjacent to the substrate 312 may be hydrogen radicals in a ground state. In some implementations, the controller 350 may include instructions for flowing a co-reactant with the one or more silicon-containing precursors into the reaction chamber 304. The co-reactant may be a hydrocarbon molecule and each of the one or more silicon-containing precursors may have at least two hydrogen atoms bonded to a silicon atom.

[0078] In some embodiments, the apparatus 300 may include a user interface associated with controller 350. The user interface may include a display screen, graphical software displays of the apparatus 300 and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0079] The computer program code for controlling the above operations can be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. Compiled object code or script is executed by the processor to perform the tasks identified in the program.

[0080] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller. The signals for controlling the process are output on the analog and digital output connections of the processing system.

[0081] In general, the methods described herein can be performed on systems including semiconductor processing equipment such as a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. In general, the electronics are referred to as the controller 350, which may controlLAMRP985WO- 11644- 1 WOvarious components or subparts of the system or systems. The controller 350, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, RF generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0082] Broadly speaking, the controller 350 may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller 350 in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials (e.g., silicon nitride), surfaces, circuits, and / or dies of a wafer.

[0083] The controller 350, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller 350 may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller 350 receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood thatLAMRP985WO- 11644- 1 WOthe parameters may be specific to the type of process to be performed and the type of tool that the controller 350 is configured to interface with or control. Thus as described above, the controller 350 may be distributed, such as by comprising one or more discrete controllers 350 that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0084] In addition to the silicon nitride deposition described herein, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0085] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0086] The apparatus / process described hereinabove may be used in conjunction with lithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, photovoltaic panels and the like. Typically, though not necessarily, such tools / processes will be used or conducted together in a common fabrication facility. Lithographic patterning of a film typically includes some or all of the following operations, each operation enabled with a number of possible tools: (1) application of photoresist on a workpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curing of photoresist using a hot plate or furnace or UV curing tool; (3) exposing the photoresist to visible or UV or x-ray light with a tool such as a wafer stepper; (4) developing the resist so as to selectively remove resist and thereby pattern it using a tool such as a wet bench; (5) transferringLAMRP985WO- 11644- 1 WOthe resist pattern into an underlying film or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.EXPERIMENTAL EXPERIMENT 1

[0087] Substrates were subject to deposition processes using the following ALD process: dichlorosilane dose, followed by conversion using plasma generated using hydrogen gas and nitrogen gas. The first set of substrates involved using hydrogen gas flows of 10 seem, 100 seem, 500 seem, 1000 seem, and 3000 seem with a plasma ON time of 2 seconds. The second set of substrates involved using hydrogen gas flows of 10 seem, 100 seem, 500 seem, 1000 seem, and 3000 seem with a plasma ON time of 5 seconds. The density of silicon nitride films was measured. Figure 4 shows the results which shows a trend whereby there is a surprising result that at about 100 seem, even though the previous trend as flow rate of hydrogen gas increased resulted in a less dense film, the trend reversed and a more dense film was observed, suggesting a higher quality film is formed at these higher flow rates.CONCLUSION

[0088] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

LAMRP985WO- 11644- 1 WOCLAIMSWhat is claimed is:

1. A method for processing substrates, the method comprising:providing a substrate to a process chamber;generating a plasma by igniting a hydrogen-containing gas and an ammonia-free nitrogen-containing gas, wherein the hydrogen-containing gas is introduced at a flow rate of greater than about 1 slm; andexposing the substrate to a halogen-containing silicon precursor to form silicon nitride on a surface of the substrate.

2. The method of claim 1, wherein the plasma is an inductively coupled plasma.

3. The method of claim 1, wherein the substrate is heated to a temperature of less than about 450°C.

4. The method of claim 1, wherein the ammonia- free nitrogen-containing gas is flowed at a flow rate of less than about 5 slm.

5. The method of claim 1, wherein the halogen-containing silicon precursor comprises a chlorine atom.

6. The method of claim 1, wherein the halogen-containing silicon precursor comprises dichlorosilane.

7. The method of claim 1, wherein the plasma is generated remotely.

8. The method of claim 1, wherein the plasma is generated upstream of the process chamber.

9. The method of claim 1, wherein all or substantially all of the radicals of hydrogen in an environment adjacent to the substrate are radicals of hydrogen in the ground state.

10. The method of claim 1, wherein the silicon nitride is formed by reacting hydrogen radicals with the halogen-containing silicon precursor.

11. The method of claim 1, wherein the hydrogen-containing gas comprises hydrogen gas (H2).LAMRP985WO- 11644- 1 WO12. The method of claim 1, wherein generating the plasma and introducing the halogencontaining silicon precursor are performed in temporally separated pulses.

13. The method of claim 1, wherein the process chamber is set to a chamber pressure of about 3 Torr to about 10 Torr.

14. An apparatus for processing substrates, the apparatus comprising:one or more process chambers, each process chamber comprising a chuck; one or more gas inlets into the process chambers and associated flow-control hardware;a remote plasma generator; anda controller having at least one processor and a memory, whereinthe at least one processor and the memory are communicatively connected with one another,the at least one processor is at least operatively connected with the flow-control hardware, andthe memory stores computer-executable instructions for controlling the at least one processor to at least control the flow-control hardware to:cause introduction of a hydrogen-containing gas to the remote plasma generator at a flow rate of at least about 1 slm;cause generation of a plasma by igniting the hydrogen-containing gas and an ammonia- free nitrogen-containing gas; andcause introduction of a halogen-containing silicon precursor to the one or more process chambers to form silicon nitride.

Images