Cyclic low-temperature film growth process

Abstract

The nitridation method includes cyclically performing in situ, in a processing chamber at a temperature below about 400°C, the following steps: treating a non-reactive surface of a substrate in the processing chamber by exposing the non-reactive surface to an energy flux to convert the non-reactive surface to a reactive surface; and nitriding the reactive surface using a nitrogen-based gas to convert the reactive surface into a nitride layer comprising the non-reactive surface.

Description

[Technical Field]

[0001] Cross-references to related patents and applications This application claims priority to and the benefit of the filing date of U.S. Nonprovisional Patent Application No. 17 / 026,168, filed September 19, 2020, which is incorporated herein by reference in its entirety.

[0002] The present invention relates generally to low temperature film growth processes, and in particular embodiments to methods and apparatus for low temperature cyclic film growth processes. [Background technology]

[0003] Device formation within a microelectronic workpiece can involve a series of manufacturing techniques involving the formation, patterning, and removal of many layers of material on a substrate. Film formation processes are essential during device formation and can be deposited and / or grown on the substrate surface. For example, film growth processes typically utilize material within the substrate (e.g., at an exposed surface) as a component of the film and / or as a seed region for crystal growth.

[0004] Nitride-based materials can be used as barrier layers, passivation layers, dielectric layers, mask layers, and substrates in the fabrication of microelectronic devices. Some examples of nitrides useful in microelectronic devices are silicon nitride, silicon oxynitride, aluminum nitride, and gallium nitride. Nitridation processes, such as thermal nitridation and plasma nitridation, are typically used to form nitride films that contain materials from the substrate as components.

[0005] Thermal and plasma-assisted film growth processes, such as nitridation, can have several drawbacks. For example, thermal nitridation processes can exceed the thermal budget of many microelectronic workpieces (e.g., where devices are already formed). Furthermore, plasma-assisted processes, such as plasma nitridation, can cause undesirable damage to the surface of the substrate. Therefore, film growth processes that occur at low temperatures that minimize substrate damage may be desirable. Summary of the Invention [Means for solving the problem]

[0006] According to one embodiment of the present invention, a nitridation method includes cyclically performing the following steps in situ in a processing chamber at a temperature below about 400°C: treating a non-reactive surface of a substrate in the processing chamber by exposing the non-reactive surface to an energy flux to convert the non-reactive surface to a reactive surface, and nitriding the reactive surface using a nitrogen-based gas to convert the reactive surface into a nitride layer comprising the subsequent non-reactive surface.

[0007] According to another embodiment of the present invention, a nitridation method includes periodically performing the following steps in situ in a plasma processing chamber at a temperature less than about 400°C: removing hydrogen from non-reactive regions of a silicon substrate by bombarding the silicon substrate with ions and photons from a plasma generated in the plasma processing chamber, thereby converting the non-reactive regions into reactive regions; and nitriding the reactive regions using hydrogenated nitrogen gas to convert the reactive regions into nitride regions that subsequently include the non-reactive regions.

[0008] According to yet another embodiment of the present invention, a method for growing a film includes cyclically performing the following steps in situ in a processing chamber at a temperature below about 400°C: treating a hydrogenated surface of a substrate in the processing chamber to convert the hydrogenated surface into a reactive surface by removing hydrogen from the hydrogenated surface using an energy flux incident on the hydrogenated surface, the substrate comprising a first material; and exposing the reactive surface to a hydrogen-based gas comprising a second material to convert the reactive surface into a film comprising a subsequent hydrogenated surface and a compound comprising the first material and the second material.

[0009] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions which should be read in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0010] [Figure 1A-B] FIG. 1A illustrates an exemplary cyclical in situ nitridation process in accordance with one embodiment of the present invention in a processing chamber at a temperature below about 400° C. FIG. 1A illustrates an initial state of a substrate including a non-reactive surface, and FIG. 1B illustrates a first processing step. [Figure 1C-D] 1A-1D illustrate an exemplary nitridation process performed cyclically in situ in a processing chamber at a temperature below about 400° C., according to one embodiment of the present invention. FIG. 1C illustrates a first nitridation step to form a nitride film, and FIG. 1D illustrates a subsequent non-reactive surface formed on the nitride film. [Figure 1E-F] 1A-1F illustrate an exemplary nitridation process according to one embodiment of the present invention, performed cyclically in situ in a processing chamber at a temperature below about 400° C. FIG. 1E illustrates the second processing step, and FIG. 1F illustrates the second nitridation step. [Figure 1G-H] FIG. 1G illustrates an exemplary cyclical nitridation process performed in situ in a processing chamber at a temperature below about 400° C., according to one embodiment of the present invention. FIG. 1G illustrates another subsequent non-reactive surface formed on the nitride film, and FIG. 1H illustrates a third processing step. [Figure 2]1 illustrates another exemplary nitridation process used to form silicon oxynitride at temperatures below about 400° C., according to one embodiment of the present invention. [Figure 3] 1 illustrates an exemplary carbonization process used to form silicon carbide at temperatures below about 400° C., according to one embodiment of the present invention. [Figure 4] 1 illustrates an exemplary film growth process performed at a temperature below about 400° C., according to one embodiment of the present invention. [Figure 5] 1 illustrates an exemplary film growth apparatus according to one embodiment of the present invention. [Figure 6] 1 illustrates an exemplary plasma processing apparatus according to one embodiment of the present invention. [Figure 7] 1 illustrates an exemplary method of nitridation according to one embodiment of the present invention. [Figure 8] 1 illustrates an exemplary method of film growth according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Corresponding numerals and symbols in different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly show relevant aspects of the embodiments and are not necessarily drawn to scale. The ends of features drawn in the figures do not necessarily indicate the ends of the ranges of the features.

[0012] Making and using various embodiments is described in detail below. However, it should be understood that the various embodiments described herein are applicable in a wide variety of specific contexts. The specific embodiments described are merely illustrative of specific ways to make and use the various embodiments and should not be construed as limiting in scope.

[0013] Nitridation (also called "nitriding") is a method of forming nitrides on the exposed surfaces of a substrate. Nitrids are formed by reacting nitrogen with the substrate material. Thermal nitridation (also called "gas nitridation") is usually performed at high temperatures (e.g., at least 600°C, typically above 900°C). The nitridation efficiency of the thermal nitridation process decreases at lower temperatures, often ceasing completely below 400°C. The nitrogen source is typically ammonia (NH3), which is supplied to the substrate by placing it in an NH3 atmosphere.

[0014] Thermal nitridation processes have various drawbacks. The high temperatures required are typically prohibitively high relative to the thermal budget of microelectronic substrates, resulting in unacceptably high substrate temperatures. For example, elevated substrate temperatures can cause uncontrolled dopant rediffusion, resulting in undesirable dopant redistribution. Other side effects on the substrate material, such as device degradation and material modification, are also possible. As a result, thermal nitridation processes are often incompatible with device fabrication processes (e.g., for advanced nodes).

[0015] Plasma nitridation is also used as a method for forming nitride on exposed surfaces of substrates. Due to its potentially lower temperatures, plasma nitridation is considered an alternative to thermal nitridation, but it is still typically performed at approximately 400°C. Although lower than 600°C, a plasma nitridation temperature of 400°C can more accurately be considered moderate relative to the thermal budget of a microelectronic substrate (e.g., not low from a device perspective). Furthermore, plasma nitridation has the additional potential drawback of inducing damage to the substrate and non-conformal nitridation.

[0016] In addition to or instead of thermal and plasma nitridation, other techniques can be used. For example, highly reactive chemicals can be used. However, this can increase costs and complexity. Techniques such as atomic layer deposition (ALD) can also be used. However, ALD is slow (e.g., 1-2 nm / min), expensive, and sensitive, requiring very pure materials, precise operating conditions, and involved surface pretreatment preparation. Furthermore, ALD, like thermal ALD and plasma-enhanced ALD, can also require high substrate temperatures.

[0017] Conventional nitridation processes disadvantageously require high temperatures (e.g., exceeding the thermal budget of the substrate) and different equipment (e.g., increasing complexity, reducing throughput, and increasing the potential for exposure to contaminants). Furthermore, conventional mechanisms for lowering nitridation temperatures are costly, cumbersome, and result in other undesirable effects, such as substrate damage. These drawbacks of conventional nitridation processes also apply to various other conventional film growth processes. Therefore, a film growth process that can be performed at low temperatures, minimizes substrate damage, and can be performed without additional specialized equipment would be desirable.

[0018] The inventors have confirmed that nitridation of silicon (Si) does not occur in an ammonia (NH3) atmosphere below 400°C. However, the reaction barrier for nitridation at low temperatures (e.g., below 400°C) may be due to passivation of the Si surface by hydrogen (H) atoms dissociated from NH3 chemisorbed on the Si surface. The inventors have discovered that dangling bonds formed by the removal of H promote nitridation at low temperatures. As a result, a completely different approach can be explored to achieve nitridation at room temperature or any low temperature below 400°C.

[0019] Furthermore, reaction barriers for other film growth processes can also be overcome or reduced by removing stopping species from the surface. For example, this concept can be extended not only to the nitridation of Si, but also to the nitridation of any semiconductor or metal surface. In addition, it is potentially useful for other film growth processes, such as nitride growth, area-selective deposition (ASD), carbide formation, and oxide formation.

[0020] In various embodiments, the film growth process includes cyclically performing a treatment step and a surface exposure step in situ in a processing chamber at a temperature below about 400° C. The treatment step includes generating an energy flux incident on a non-reactive surface of a substrate in the processing chamber to convert the non-reactive surface into a reactive surface. For example, the non-reactive surface may be a hydrogenated (i.e., hydrogen-terminated) surface, and the energy flux can remove some or all of the hydrogen to produce a reactive surface (e.g., having dangling bonds).

[0021] The surface exposure step involves exposing the reactive surface to a precursor gas (e.g., a hydrogen-based gas) containing a reactive material. The reactive material of the precursor gas reacts with the surface and subsurface of the substrate, including the bulk material, to form a film containing a compound formed from the reactive material and the bulk material. The film formed by the reaction also contains a subsequent non-reactive surface. That is, the surface of the film exposed to the precursor gas becomes less reactive over time, resulting in additional non-reactive surfaces available for processing in subsequent processing steps of the next cycle (e.g., the process is self-limiting).

[0022] In various embodiments, the film growth process is a nitridation process. The temperature may be significantly lower than 400°C (e.g., less than about 250°C or room temperature). The energy flux may be provided using energetic particles, thermal flashing, or other suitable means. In some embodiments, the processing chamber is a plasma processing chamber, and the energy flux is provided using a plasma generated within the plasma processing chamber. The substrate may be any suitable substrate, and in some embodiments, comprises Si. In one embodiment, the precursor gas is NH3 gas.

[0023] The film growth processes described herein can advantageously enable film growth (e.g., thermal nitridation of Si or other surfaces) at low temperatures below about 400°C, such as below about 250°C or about room temperature. Room temperature / low temperature nitridation or nitride growth can be highly beneficial for process integration and new capital equipment development. For example, the film growth process can add value to current equipment through an extended process window.

[0024] The film growth processes of embodiments may be beneficial for both logic and memory devices and processes. The film growth processes (e.g., nitridation and / or nitride growth processes) may advantageously avoid the need for high temperatures (e.g., thermal processes) or moderate temperatures (e.g., plasma processes), which may be beneficial for device performance and process integration.

[0025] Additionally, the layer-by-layer self-limiting film growth process can advantageously be achievable at low temperatures below room temperature / about 400°C. A further advantage would be to enable area-selective film growth (e.g., ASD) on different regions of a Si surface. This mechanism can advantageously be extended from Si surfaces to other suitable surfaces, such as other semiconductor, metal, and dielectric surfaces.

[0026] The embodiments provided below describe various methods and apparatus for film growth processes, particularly low-temperature cyclic film growth processes. The following description describes these embodiments. FIGS. 1A-1H are used to describe an exemplary nitridation process. Another example of a nitridation process is described using FIG. 2. FIGS. 3 and 4 are used to describe an exemplary carbonization process and an exemplary film growth process, respectively. Two exemplary apparatuses are described using FIGS. 5 and 6, while an exemplary nitridation method is described using FIG. 7 and an exemplary film growth method is described using FIG. 8.

[0027] Figures 1A, 1B, 1C, 1D, 1E, 1F, 1G, and 1H illustrate an exemplary nitridation process performed cyclically in situ in a processing chamber at a temperature below about 400°C in accordance with one embodiment of the present invention. Figure 1A illustrates an initial state of a substrate including a non-reactive surface, Figure 1B illustrates a first processing step, Figure 1C illustrates a first nitridation step to form a nitride film, Figure 1D illustrates a subsequent non-reactive surface formed on the nitride film, Figure 1E illustrates a second processing step, Figure 1F illustrates a second nitridation step, Figure 1G illustrates another subsequent non-reactive surface formed on the nitride film, and Figure 1H illustrates a third processing step.

[0028] 1A, the nitridation process 100 includes an initial state of a substrate 110 including a bulk region 118 and a non-reactive surface 111. The non-reactive surface 111 may be a passivated surface that has been passivated by a terminating bond. For example, the non-reactive surface 111 may be a hydrogenated surface as shown. Alternatively, the non-reactive surface 111 may be terminated with another species (i.e., a species different from the material of the substrate 110 that reacts with nitrogen to form a nitride).

[0029] In various embodiments, substrate 110 is a semiconductor substrate, and in one embodiment, is a silicon substrate. In another embodiment, the semiconductor substrate may be germanium (Ge) or a compound semiconductor including gallium (Ga), arsenic (As), nitrogen (N), etc. Alternatively, substrate 110 may be a metal substrate or a dielectric substrate. For example, substrate 110 may be aluminum, carbon (e.g., graphene), or silicon oxide (SiO2). Furthermore, substrate 110 may include many different layers of materials and may be the top layer of a multi-layer substrate. For example, substrate 110 may be SiO2 formed on another material.

[0030] The substrate 110 is placed in a processing chamber 102. The processing chamber 102 may be any suitable processing chamber 102. However, the processing chamber 102 need only be a low-temperature processing chamber (e.g., it need not be capable of heating the substrate above about 400° C.). In various embodiments, the processing chamber 102 is a multipurpose processing chamber, and in one embodiment, is a plasma processing chamber.

[0031] 1B, the nitridation process 100 further includes a first processing step performed in situ within the processing chamber 102, in which an energy flux 120 is provided to the non-reactive surface 111 of the substrate 110. The energy flux 120 converts the non-reactive surface 111 to a reactive surface 112. For example, if the non-reactive surface 111 is a hydrogenated surface (as shown), the energy flux 120 imparts sufficient energy to the non-reactive surface 111 to remove hydrogen, leaving behind a reactive surface 112. As shown, the reactive surface 112 can be reactive as a result of dangling bonds formed at the surface (e.g., reaction with the reactive surface 112 can be energetically favorable).

[0032] In some cases, the energy flux 120 or treatment duration can be such that only regions of the non-reactive surface become reactive. For example, non-reactive regions (e.g., qualitatively indicated by non-reactive regions 131) can be converted to reactive regions (e.g., reactive regions 132), while other portions of the non-reactive surface 111 remain non-reactive (e.g., terminated with hydrogen). That is, the treatment does not remove all hydrogen during each cycle.

[0033] The energy flux 120 can expose bulk material 140 of the substrate 110 at the reactive surface 112. For example, the bulk region 118 of the substrate 110 can include the bulk material 140. In this example, the bulk material 140 is Si, although other bulk materials are possible. For purposes of this disclosure, the term bulk refers to the material that makes up the majority of the substrate 110 (which may be the top layer of a multi-layer substrate).

[0034] The energy flux 120 can be delivered to the substrate using any suitable method that does not raise the substrate temperature above 400° C. or damage structures underlying the substrate 110. For example, the energy flux 120 can be delivered to the substrate 110 using energetic particles (e.g., ions, electrons, radicals, photons). In various embodiments, the energy flux 120 is a beam of energetic particles, and in some embodiments, a mixture of energetic particles generated by a plasma. For example, the energy flux 120 can be delivered to the substrate 110 using electron beam irradiation, ion beam irradiation (e.g., Ar + , He + These may include irradiation with ultraviolet (UV) light (i.e., wavelengths less than 400 nm), inert radical beam irradiation, inert gas plasma (e.g., He plasma, Ar plasma, etc.), or thermal flashing of a non-reactive surface above 400°C followed by a quick return to low temperature.

[0035] In one embodiment, the energy flux 120 is generated by a helium (He) plasma. An inert gas plasma, such as a He plasma, can serve as an energy flux source that is a combination of energetic particle beams (ions, electrons, radicals, and photons). The He plasma generates ions (He) that have enough energy to break the bonds of terminating species without damaging the surface of the substrate 110. + ) and photons. For example, in the specific example of S-H bonds (as shown), the energy flux 120 can provide at least about 4.06 eV to the S-H bonds of the non-reactive surface 111. That is, the average energy of the ions and photons can be at least about 4.06 eV. However, in some cases, lower energies may be sufficient to remove H from the surface (e.g., to provide the necessary energy for agglomeration). For example, the average energy of the ions and photons can be lower than 4.06 eV (e.g., as low as 1.114 eV or less).

[0036] The energetic particles produced by He plasma can include, for example, energetic ions, radicals, electrons, and photons. In the specific example of He plasma, the emitted photons (e.g., UV photons) can have favorable energies (e.g., about 24 eV). In particular, He can offer the dual advantages of being lightweight so that impacts cause minimal or no damage to the substrate surface (e.g., Si / SiN surface), and high-energy photons (about 24 eV), ions, and radicals that can advantageously and efficiently remove termination species (e.g., H) from the surface.

[0037] It should be noted that the energy required to efficiently cleave surface bonds can vary depending on how the energy is absorbed by the non-reactive surface 111. For example, energy from the incident particle can be spread among several localized surface atoms, which can increase the required particle energy. Furthermore, the desorption cross section of the terminating species can be energy dependent, and maximizing the cross section can advantageously improve efficiency. While not critical in most cases due to the self-limiting nature of the process, uniformity of the energy flux 120 to the substrate can be desirable.

[0038] In another embodiment, the energy flux 120 can be partially or completely generated using techniques such as thermal flashing (e.g., millisecond flashing) or focused particle beams (e.g., ion beam sources, electron beam sources such as electron guns, photon sources such as UV lamps, radical sources such as radical generators, etc.). For example, thermal flashing and / or focused particle beams can advantageously direct energy to localized regions of the non-reactive surface 111 (e.g., non-reactive regions 131), enabling area-selective film growth (e.g., ASD). The specific choice of energy source can depend on various factors, such as ease of implementation, energy budget, uniformity, efficiency, and device process compatibility.

[0039] 1C, the nitridation process 100 further includes a nitridation step that includes supplying a precursor gas 122 into the processing chamber 102. The precursor gas 122 includes a reactive material 141 (e.g., N) that reacts with bulk material 140 (e.g., Si) from the substrate 110. For example, the precursor gas 122 can be introduced into the processing chamber 102 after a processing step, or can be present throughout the nitridation process 100. The precursor gas 122 is a hydrogen-based gas in various embodiments, and in some embodiments, is a hydrogenated nitrogen gas (N m H n , also known as nitrogen hydrides).

[0040] For example, the precursor gas 122 may be hydrazine (N2H4) or cycloazane (N m H m ) and other Azan (N m H m+2 ), and ammonium (NH + The precursor gas 122 may include nitrogen-based ions such as argon (Ar). In one embodiment, the precursor gas 122 is ammonia (NH3) as shown. The precursor gas 122 may be supplied with other gases, such as an inert gas (e.g., a carrier gas). In one embodiment, the precursor gas 122 is NH3 and is supplied with argon (Ar) in a 1:4 ratio (NH3:Ar).

[0041] However, other functional groups and elements besides N and H may also be included. Furthermore, the precursor gas 122 may be nitrogen-free. In some embodiments, the precursor gas 122 is a hydrocarbon gas, while in other embodiments, the precursor gas 122 is another hydrogen-based gas. The inclusion of hydrogen in the precursor gas may be influenced by the type of substrate. For example, hydrogen may be included in the precursor gas if the non-reactive surface 111 is terminated with hydrogen with each cycle, but may be another element or functional group in other cases.

[0042] NH3 (and other nitrogen hydride precursors, for example) can be produced by nitridation without heating the substrate. x (x=1, 2) and H(+H). Furthermore, in the presence of a reactive surface 112 (e.g., with dangling bonds from surface Si atoms), nitridation will advantageously be thermodynamically favorable at any substrate temperature (i.e., there is little reaction barrier to nitridation when dangling bonds are available). Note that in FIG. 1C and other similar figures, the nitrided surface sites are depicted as N for clarity, but may also be, for example, NH x It should be noted that other nitrogen-containing species such as (x=1, 2) are also possible. Similar concepts apply to reactive species other than N.

[0043] The treatment steps can be performed in a vacuum (e.g., medium or high vacuum). Additionally, the treatment steps can be performed in a non-hydrogen environment (e.g., without the presence of ambient hydrogen-based gases such as NH), after which the precursor gas 122 can be introduced simultaneously with (or after a delay in) stopping the treatment process (e.g., the H removal process). For example, the source power of the energy source providing the energy flux 120 can be removed (i.e., stopped), and the nitridation step can be initiated by introducing the precursor gas 122 into the process chamber 102.

[0044] Alternatively, the treatment step and the nitridation step may be performed simultaneously. That is, an energy flux 120 (e.g., an inert plasma such as a He plasma) may be supplied into the process chamber 102 simultaneously with a precursor gas 122 (e.g., NH). In this scenario, H atoms may be continuously accumulated and removed from the exposed surface of the substrate 110, such that even as H passivates regions of the surface, thermodynamically (i.e., energetically) favorable sites are always created. Such a scenario may be an example of a situation that results in the formation of non-reactive regions 131 and reactive regions 132, rather than the entire surface or a significant portion of the surface being non-reactive or reactive at any given time.

[0045] 1D, the nitridation step of nitridation process 100 continues as reactive material 141 of precursor gas 122 continues to form bonds with bulk material 140 of substrate 110 to form nitride layer 142 including nitride compound 144. As shown, nitride compound 144 includes bonds (Si—N) between reactive material 141 and bulk material 140. In one embodiment, nitride compound 144 is Si3N4.

[0046] However, the precursor gas 122 also converts the reactive surface 112 into a subsequent non-reactive surface 111, making the nitridation step self-limiting. That is, the nitridation reaction at the surface of the substrate 110 may slow down or stop as reactive sites (e.g., dangling bonds) become occupied by terminating species (e.g., H). For example, dangling bonds in Si may promote nitridation, but nitridation may not proceed if the dangling bonds are unavailable, such as when they are passivated by H atoms as shown.

[0047] As a result, the treatment and nitridation steps may be repeated cyclically to advantageously form nitride layers in a layer-by-layer (or substantially layer-by-layer) process. Such layer-by-layer control can enable high uniformity and / or precise thickness control.

[0048] The in situ cyclic process can advantageously be performed at much higher speeds compared to traditional layer-by-layer processes (such as ALD, which involve steps on the order of minutes). For example, both the treatment step and the nitridation step can occur in a matter of seconds. In one embodiment, the treatment step occurs in less than about 5 seconds. In one embodiment, the nitridation step occurs in less than about 5 seconds. The timescales of the treatment and nitridation steps can depend on the energy flux, cycle efficiency, gas flow rate, pump speed, and / or temperature (e.g., higher temperatures are faster). The respective durations of the treatment and nitridation steps can be similar or different, depending on the specific details of a given implementation of the nitridation process.

[0049] Furthermore, due to the in situ performance of the nitridation process, nitrides can also be advantageously formed after other manufacturing processes without removing the substrate from the processing chamber. For example, the processing chamber may be a multi-purpose processing chamber that is used as a plasma processing chamber before and / or after being used as a nitridation processing chamber for the nitridation process.

[0050] 1E, 1F, 1G, and 1H, the treatment and nitridation steps are repeated in a cyclical manner to show the continued formation of a nitride layer 142 of increasing thickness on the substrate 110. A second treatment step is performed to convert the subsequent non-reactive surface 111, formed as a result of the self-limiting nature of the previous nitridation step, into a reactive surface 112 (FIG. 1E), which is then converted back into a non-reactive surface 111 (FIG. 1G) during a second nitridation step (FIG. 1F) after the nitride layer 142 has increased in thickness. Energy flux 120 is again applied in a third treatment step (FIG. 1H), and so on.

[0051] Each of the above steps is performed at a temperature below about 400°C. For example, the temperature can be below about 250°C, and can be room temperature. Room temperature can generally be defined as a low temperature (e.g., about 20°C to about 40°C, such as 25°C, 22°C, etc.) and can refer to the ambient temperature within the processing chamber. However, "room temperature" can also refer to a situation where no additional chamber or substrate heating is applied during the process (e.g., energy flux may result in localized surface heating). Additionally, the above steps can also be performed at temperatures below room temperature (e.g., 0°C or below).

[0052] Importantly, the entire substrate does not heat up above about 400°C, and in many cases much lower. For example, Si-NH x Additional chamber or substrate heating can be avoided unless desired for the formation of a bonded film. For example, in some embodiments, the chamber temperature can be maintained at about 250° C. to form a ternary compound containing Si, N, and H (silicon nitride hydride). That is, temperatures (less than about 400° C., and even less than about 250° C.) can be useful for controlling the hydrogen content of the nitride layer.

[0053] In the case of thermal flashing, the temperature of the substrate surface can be raised locally on the order of milliseconds to provide the necessary energy to non-reactive surfaces, while avoiding damage to other areas of the substrate.

[0054] Figure 2 illustrates another example of a nitridation process used to form silicon oxynitride at temperatures below about 400°C in accordance with one embodiment of the present invention. The nitridation process of Figure 2 may be a specific implementation of other film growth processes (e.g., nitridation processes) described herein, such as, by way of example, the nitridation processes of Figures 1A-1H or the film growth process of Figure 4. Similarly labeled elements may be as described above.

[0055] 2, nitridation process 200 includes substrate 210, which includes bulk region 218 and nitride layer 242. Note that here and below, conventions are adopted for brevity and clarity, where elements following the pattern [x10] may be related implementations of plasma processing chambers in various embodiments. For example, substrate 210 may be similar to substrate 110 unless otherwise specified. Similar conventions are adopted for other elements, as will become apparent from the use of similar terms in combination with the aforementioned three-digit numbering system.

[0056] 1A-1H。 Nitridation process 200, for simplicity and clarity, is shown only with a representative self-limiting stage of the nitridation step, the remaining steps are similar to those of Figures 1A-1H, but there are differences, some of which are explained below. In nitridation process 200, substrate 210 is an oxide (e.g., bulk or an oxide layer on a multi-layer substrate). Bulk region 218 of substrate 210 includes SiO2 as shown, resulting in a bulk material 240 that includes both Si and O.

[0057] The precursor gas 222 is provided during a nitridation step following or during a processing step that provides an energy flux to the non-reactive surface 211 of the substrate 210. The precursor gas 222 is a nitrogen hydride gas containing a reactive material 241 (N as shown), but can be other gases as described above. In one embodiment, the precursor gas 222 is NH.

[0058] The resulting nitride layer 242 includes an oxynitride compound 244 formed from the reaction of reactive material 241 (N) with bulk material 240 (Si and oxygen, O). In one specific example, oxynitride compound 244 is silicon oxynitride (e.g., SiNO, or with some degree of amorphousness with local variations between SiO and SiN), although the nitridation process 200 can be generalized to the formation of other oxynitrides.

[0059] Figure 3 illustrates an exemplary carbonization process used to form silicon carbide at temperatures below about 400°C according to one embodiment of the present invention. The carbonization process of Figure 3 may be a specific implementation of other film growth processes described herein, such as the film growth process of Figure 4. Similarly labeled elements may be as described above.

[0060] Referring to Figure 3, carbonization process 300 includes a substrate 310 including a bulk region 318 and a carbide layer 342. As with Figure 2, carbonization process 300 is shown only with a representative self-limiting stage of the carbonization step (similar to a nitridation step) for brevity and clarity. The remaining steps are similar to those of Figures 1A-1H, but there are differences, some of which are described below.

[0061] In carbonization process 300, substrate 310 is a semiconductor, and in some embodiments is Si (e.g., a Si layer on a bulk or multi-layer substrate). Bulk region 318 of substrate 310 includes bulk Si material 340 as shown. Precursor gas 322 is provided during a carbonization step following or during a processing step that provides an energy flux to non-reactive surface 311 of substrate 310.

[0062] In contrast to the precursors previously described, precursor gas 322 is a hydrocarbon gas containing reactive material 341 (carbon, C, as shown), although other C-containing gases may be used. In various embodiments, precursor gas 322 is an alkane. Alternatively, or in addition, precursor gas 322 includes other hydrocarbon gases, such as alkenes, alkynes, and / or cyclic and substituted variations. In one embodiment, precursor gas 322 includes methane (CH). In one embodiment, precursor gas 322 includes ethylene (CH).

[0063] The resulting carbide layer 342 includes a carbide compound 344 formed from the reaction of reactive material 341 (C) with bulk material 340 (Si). In one specific example, carbide compound 344 is silicon carbide (SiC), although the carbonization process 300 can be generalized to the formation of other carbides.

[0064] Figure 4 illustrates an example of a film growth process performed at a temperature less than about 400°C in accordance with one embodiment of the present invention. The film growth process of Figure 4 may be a general implementation of other film growth processes (e.g., nitridation processes or carbonization processes) described herein, such as the nitridation processes of Figures 1A-1H and 2 or the carbonization process of Figure 3. Similarly labeled elements may be as described above.

[0065] Referring to Figure 4, film growth process 400 includes a substrate 410 including a bulk region 418 and a film 442. As with Figure 2, film growth process 400 is shown only with a representative self-limiting stage of the film growth step (which is a generalization of the nitridation step) for brevity and clarity. The remaining steps are similar to those of Figures 1A-1H, but there are differences, some of which are explained below.

[0066] Film 442 is formed during a film growth step in which precursor gas 422 is supplied, following or during a processing step that supplies an energy flux to the non-reactive surface 411 of substrate 410. Film 442 is the result of a reaction between reactive material 441 of precursor gas 422 and bulk material 440 of substrate 410.

[0067] In this generalized scenario, reactive material 441 is represented as some species Z (specific examples of which were N and C), while bulk material 440 is represented as some species X (specific examples include Si and Si, O). Film 442 then includes compound 444 containing X and Z (e.g., XZ bond). For example, X can be C (e.g., if substrate 410 is graphene), aluminum (Al), and others not specifically listed. Similarly, Z can be O, a reactive functional group, and others.

[0068] Figure 5 shows an example of a film growth apparatus according to one embodiment of the present invention. The film growth apparatus of Figure 5 can be used to perform any of the film growth processes described herein, such as the film growth processes of Figures 1A-1H and 2-4. The film growth apparatus of Figure 5 can also be used to perform film growth methods such as those described below in Figures 7 and 8. Similarly labeled elements can be as described above.

[0069] 5, a film growth apparatus 500 includes a substrate holder 504 that supports a substrate 510 within a process chamber 502. For example, the process chamber 502 may be a multi-purpose process chamber. Various gases, such as a precursor gas 522 (shown here as NH), may be supplied to the process chamber 502 via one or more gas inlets 506. Pressure (e.g., medium vacuum, high vacuum, etc.) may be controlled within the process chamber 502 using a pump 508 that exhausts the precursor gas 522 and other gases from the process chamber 502 through one or more gas outlets 507.

[0070] The energy source 514 provides an energy flux 520 to the surface 512 of the substrate 510. As previously mentioned, the energy flux 520 can be provided after or during the precursor gas 522. The energy source 514 can be any suitable energy source or combination of energy sources, such as a plasma source, an ion beam source, an electron beam source, a photon source (e.g., a UV light source), a radical beam source, a thermal flashing source, or the like.

[0071] If temperature control (i.e., below about 400° C.) is desired, an optional temperature controller 516 can be included to control the temperature of the substrate holder 504 and / or the substrate 510. The optional temperature controller 516 can also include an energy source, such as a thermal flash source, in some implementations.

[0072] Figure 6 shows an example of a plasma processing apparatus according to an embodiment of the present invention. The plasma processing apparatus of Figure 6 can be used to perform any of the film growth processes described herein, such as the film growth processes of Figures 1A-1H and 2-4. Additionally, the plasma processing apparatus of Figure 6 may be used to perform film growth methods such as those described below in Figures 7 and 8. Similarly labeled elements may be as described above.

[0073] 6, a plasma processing apparatus 600 includes a substrate holder 604 that supports a substrate 610 in a plasma processing chamber 602. The plasma processing apparatus of FIG. 6 may be a specific implementation of the film growth apparatus of FIG. 5, in which the energy source is a plasma source 614 and the energy flux to a surface 612 of the substrate 610 is provided by a plasma 620 generated in the plasma processing chamber 602. For example, the plasma 620 may be an inert plasma (e.g., a He plasma) generated using an inert gas 624 (e.g., He) supplied through one or more gas inlets 606.

[0074] The precursor gas 622 may be supplied through a gas inlet 606 (e.g., the same gas inlet as the inert gas 624 or a dedicated gas inlet). A pump 608 exhausts the precursor gas 622, the inert gas 624, and any other gases from the plasma processing chamber 602 through one or more gas outlets 607. As previously mentioned, an optional temperature controller 616 can be included if temperature control of the substrate is desired.

[0075] FIG. 7 illustrates an exemplary method of nitridation according to one embodiment of the present invention. The method of FIG. 7 can be combined with other methods and processes and can be performed using any of the film growth apparatuses described herein, such as, for example, the film growth apparatus of FIG. 5 or the plasma processing apparatus of FIG. 6. Furthermore, the method of FIG. 7 can apply some or all of the steps of any of the process embodiments described herein, such as, for example, the nitridation process of FIGS. 1A-1H or the film growth process of FIG. 4. While shown in a logical order, the arrangement and numbering of the steps in FIG. 7 are not intended to be limiting. The steps of the method of FIG. 7 can be performed in any suitable order or concurrently with one another, as will be apparent to one of ordinary skill in the art.

[0076] 7, method step 701 of nitridation method 700 involves treating a non-reactive surface of a substrate by exposing the non-reactive surface to an energy flux, thereby converting the non-reactive surface to a reactive surface. Step 702 of nitridation method 700 involves nitriding the reactive surface using a nitrogen-based gas, thereby converting the reactive surface into a nitride layer comprising the non-reactive surface. Steps 701 and 702 are performed in a processing chamber (i.e., in situ without removing the substrate from the processing chamber) at a temperature below about 400° C.

[0077] Step 703 is to cyclically perform steps 701 and 702. Specifically, step 702 can be self-limiting due to subsequent non-reactive surfaces that can be removed by a subsequent processing step (step 701). The nitridation method 700 can continue until a desired uniformity and / or thickness of the nitride film is achieved. In some cases, metrology (e.g., in situ) can be used to dynamically measure the state of the nitride layer so that processing conditions can be adjusted or the cycle can be terminated at the appropriate time. For example, in situ ellipsometry can be used. Additionally, insight can be gained from the ratio of species (e.g., N / H signal ratio) in the energy flux (e.g., plasma generation).

[0078] FIG. 8 illustrates an exemplary method of film growth according to one embodiment of the present invention. The method of FIG. 8 can be combined with other methods and processes and can be performed using any of the film growth apparatuses described herein, such as, for example, the film growth apparatus of FIG. 5 or the plasma processing apparatus of FIG. 6. Additionally, the method of FIG. 8 can apply some or all of the steps of any of the process embodiments described herein, such as, for example, the nitridation process of FIGS. 1A-1H or the film growth process of FIG. 4. While shown in a logical order, the arrangement and numbering of the steps in FIG. 8 are not intended to be limiting. The steps of the method of FIG. 8 can be performed in any suitable order or concurrently with one another, as will be apparent to one of ordinary skill in the art.

[0079] Referring to Figure 8, step 801 of film growth method 800 involves treating a hydrogenated surface of a substrate to convert it into a reactive surface by removing hydrogen from the hydrogenated surface using an energy flux incident on the hydrogenated surface. The substrate includes a first material. In step 802, the reactive surface is exposed to a hydrogen-based gas containing a second material to convert the reactive surface into a film. The film then includes the hydrogenated surface and a compound including the first and second materials. Steps 801 and 802 are performed in a processing chamber at a temperature below about 400°C. Step 803 is to periodically perform steps 801 and 802.

[0080] Illustrative embodiments of the present invention are summarized here. Other embodiments can be seen throughout the specification and claims filed herewith. [Example]

[0081] Example 1. A method of nitridation comprising cyclically performing the following steps in situ in a processing chamber at a temperature below about 400°C: treating a non-reactive surface of a substrate in said processing chamber by exposing the non-reactive surface to an energy flux to convert said non-reactive surface to a reactive surface; and nitriding said reactive surface using a nitrogen-based gas to convert said reactive surface into a nitride layer comprising the subsequent non-reactive surface.

[0082] Example 2. The method of Example 1, further comprising: each treatment of the non-reactive surface occurring for less than about 5 seconds; and each nitriding of the reactive surface occurring for less than about 5 seconds.

[0083] Example 3. The method of example 1 or 2, wherein the nitrogen-based gas comprises ammonia (NH3).

[0084] Example 4. The method of any one of Examples 1-3, wherein treating the non-reactive surface comprises providing the energy flux using a plasma generated within the treatment chamber.

[0085] Example 5. The method of any one of Examples 1-4, wherein treating the non-reactive surface comprises providing an energy flux using an ion beam source, an electron beam source, a photon source, a radical source, or a thermal flashing source.

[0086] Example 6. The method of any one of Examples 1-5, wherein treating the non-reactive surface comprises simultaneously applying source power to generate an energy flux and preventing diffusion of the nitrogen-based gas into the processing chamber; and nitriding the reactive surface comprises simultaneously removing the source power and supplying the nitrogen-based gas into the processing chamber.

[0087] Example 7. A method of nitridation comprising periodically performing the following steps in situ in a plasma processing chamber at a temperature less than about 400°C: removing hydrogen from non-reactive regions of a silicon substrate by bombarding the silicon substrate with ions and photons from a plasma generated in the plasma processing chamber, thereby converting the non-reactive regions into reactive regions; and nitriding the reactive regions using hydrogenated nitrogen gas to convert the reactive regions into nitride regions that subsequently include the non-reactive regions.

[0088] Example 8. The method of Example 7, wherein the ions and photons comprise an average energy greater than about 4.06 eV.

[0089] Example 9. The method of example 7 or 8, wherein the removal of hydrogen from the non-reactive regions and the nitridation of the reactive regions occur simultaneously.

[0090] Example 10. The method of any one of Examples 7-9, wherein the nitrogen hydride gas comprises ammonia (NH3).

[0091] Example 11. The method of any one of Examples 7-10, wherein the plasma generated in the plasma processing chamber is a helium plasma.

[0092] Example 12. The method of any one of Examples 7-11, wherein the temperature is less than about 30°C.

[0093] Example 13. A method of growing a film comprising cyclically performing the following steps in situ in a processing chamber at a temperature below about 400°C: treating a hydrogenated surface of a substrate in the processing chamber to convert the hydrogenated surface into a reactive surface by removing hydrogen from the hydrogenated surface using an energy flux incident on the hydrogenated surface, the substrate comprising a first material; and exposing the reactive surface to a hydrogen-based gas comprising a second material to convert the reactive surface into a film comprising a subsequent hydrogenated surface and a compound comprising the first material and the second material.

[0094] Example 14. The method of Example 13, further comprising heating the substrate to a temperature of about 250° C. before cyclically repeating the steps, and maintaining the temperature while cyclically repeating the steps.

[0095] Example 15. The method of Example 13 or 14, further comprising treating the substrate in the processing chamber with a plasma process before periodically repeating the steps, wherein the substrate is not removed from the processing chamber between the plasma process and periodically performing the steps.

[0096] Example 16. The method of Example 15, wherein treating the hydrogenated surface of the substrate comprises thermally flashing the hydrogenated surface to locally increase the temperature of the hydrogenated surface.

[0097] Example 17. The method of any one of Examples 13-16, wherein treating the hydrogenated surface comprises treating the hydrogenated surface with a plasma generated in the treatment chamber.

[0098] Example 18. The method of any one of Examples 13-17, wherein the first material is nitrogen, the second material is silicon, and the compound is silicon nitride.

[0099] Example 19. The method of any one of Examples 13-17, wherein the first material is nitrogen, the second material is silicon oxide, and the compound is silicon oxynitride.

[0100] Example 20. The method of any one of Examples 13-17, wherein the first material is carbon, the second material is silicon, and the compound is silicon carbide.

[0101] While the present invention has been described with reference to exemplary embodiments, this specification is not intended to be construed in a limiting sense. Various modifications and combinations of those exemplary embodiments, as well as other embodiments of the present invention, will become apparent to those skilled in the art upon reference to this specification. It is therefore intended that the appended claims cover any and all such modifications or embodiments.

Claims

1. In a processing chamber at a temperature below 400° C., the following steps: treating a non-reactive surface of a substrate in the processing chamber by exposing the non-reactive surface to an energy flux to convert the non-reactive surface to a reactive surface; and nitriding the reactive surface using a nitrogen-based gas without generating a plasma to convert the reactive surface into a nitride layer that subsequently comprises a non-reactive surface; periodically in situ, Each treatment of the non-reactive surface occurs for less than 5 seconds; and each nitriding of the reactive surface occurs for less than 5 seconds; treating the non-reactive surface comprises providing an energy flux using an ion beam source, an electron beam source, a photon source, a radical source, or a thermal flashing source; Methods for nitriding.

2. The nitrogen-based gas is ammonia (NH ３ 10. The method of claim 1, comprising:

3. The method of claim 1 , wherein treating the non-reactive surface comprises providing the energy flux using a plasma generated within the processing chamber.

4. treating the non-reactive surface applying a source power to generate the energy flux; simultaneously preventing diffusion of the nitrogen-based gas into the processing chamber; nitriding the reactive surface, removing the source power; simultaneously supplying the nitrogen-based gas into the processing chamber. The method of claim 1.

5. In a plasma treatment chamber at a temperature below 400° C., the following steps: removing hydrogen from non-reactive regions of the silicon substrate by bombarding the silicon substrate with ions and photons from a plasma generated in the plasma processing chamber, thereby converting the non-reactive regions into reactive regions; and nitriding the reactive regions using hydrogenated nitrogen gas without generating a plasma with the hydrogenated nitrogen gas to convert the reactive regions into nitride regions including subsequent non-reactive regions; periodically in situ, A method for nitridation that simultaneously removes the hydrogen from the non-reactive regions and nitrides the reactive regions.

6. 6. The method of claim 5, wherein the ions and photons comprise an average energy greater than 4.06 eV.

7. The nitrogen hydride gas is ammonia (NH ３ 6. The method of claim 5, comprising:

8. The method of claim 5 , wherein the plasma generated in the plasma processing chamber is a helium plasma.

9. 6. The method of claim 5, wherein the temperature is less than 30°C.

10. In a processing chamber at a temperature below 400° C., the following steps: treating the hydrogenated surface of a substrate in the processing chamber to convert the hydrogenated surface into a reactive surface by removing hydrogen from the hydrogenated surface using an energy flux incident on the hydrogenated surface, the substrate comprising a first material; exposing the reactive surface to a hydrogen-based gas containing a second material without generating a plasma to convert the reactive surface into a film comprising a subsequently hydrogenated surface and a compound containing the first material and a second material; periodically in situ, further comprising heating the substrate to a temperature of 250° C. before cyclically repeating the steps, and maintaining the temperature while cyclically repeating the steps; A method for film growth, wherein treating the hydrogenated surface of the substrate comprises thermally flashing the hydrogenated surface to locally increase the temperature of the hydrogenated surface.

11. 11. The method of claim 10, further comprising treating the substrate in the processing chamber with a plasma process before periodically repeating the steps, wherein the substrate is not removed from the processing chamber between the plasma process and periodically performing the steps.

12. The method of claim 10 , wherein treating the hydrogenated surface comprises treating the hydrogenated surface with a plasma generated in the processing chamber.

13. The method of claim 10, wherein the first material is silicon, the second material is nitrogen, and the compound is silicon nitride.

14. 11. The method of claim 10, wherein the first material is silicon oxide, the second material is nitrogen, and the compound is silicon oxynitride.

15. The method of claim 10, wherein the first material is silicon, the second material is carbon, and the compound is silicon carbide.

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