Conformal metal dichalcogenides

Abstract

This paper describes transition metal disulfide films and methods for depositing transition metal disulfide films on substrates. It also describes methods for converting transition metal oxide films into transition metal disulfide films. A substrate is exposed to a metal precursor and an oxidant to form a transition metal oxide film; the transition metal oxide film is then exposed to a chalcogenide precursor to form a transition metal disulfide film.

Description

Technical Field

[0001] The embodiments of the present invention are generally related to methods for forming transition metal dichalcogenides (TMDCs). In particular, the embodiments of the present invention relate to forming TMDC films for memory and logic applications. Prior Technology

[0002] The semiconductor processing industry continues to strive for higher production volumes while increasing the uniformity of layers deposited on larger surface areas. These same factors, combined with new material combinations, also provide greater integration of circuitry per unit area of ​​the substrate. As circuit integration increases, the demand for greater uniformity and processing control over layer thickness grows. Therefore, various technologies have been developed to deposit layers on substrates cost-effectively while maintaining control over layer characteristics.

[0003] Chemical vapor deposition (CVD) is one of the most common deposition processes used to deposit layers on substrates. CVD is a flux-dependent deposition technique that requires precise control of substrate temperature and the precursor introduced into the processing chamber to produce a desired layer of uniform thickness. As substrate size increases, these requirements become increasingly critical, creating greater demands for complexity in chamber design and airflow techniques to maintain proper uniformity.

[0004] A variant of CVD exhibiting superior stepped coverage is cyclic deposition, or atomic layer deposition (ALD). Cyclic deposition is based on atomic layer epitaxy (ALE) and utilizes chemisorption techniques to sequentially deliver precursor molecules onto a substrate surface. This cycle exposes the substrate surface to a first precursor, a purge gas, a second precursor, and another purge gas. The first and second precursors react to form a product compound as a film on the substrate surface. This cycle is repeated to form this layer to the desired thickness.

[0005] The increasing complexity of advanced microelectronic devices places stringent demands on currently used deposition techniques. Unfortunately, only a limited number of viable chemical precursors possess the necessary properties for robust thermal stability, high reactivity, and vapor pressure suitable for film growth.

[0006] Transition metal dichalcogenides (TMDCs) are known as excellent candidates to mitigate metal migration issues associated with the miniaturization of film interconnects. Furthermore, TMDCs offer better conductivity and carrier mobility compared to current processes in 3D NAND devices. However, recent TMDC methods require high-temperature processing, which may be incompatible with the device's thermal budget.

[0007] Therefore, there is a need for conformal TMDCs that can be grown through low-temperature heat treatment and are suitable for integration into devices in temperature-sensitive structures. Summary of the Invention

[0008] One or more embodiments of the present invention relate to a method for forming a transition metal disulfide film. This method includes depositing a transition metal oxide film on a substrate surface; and converting the transition metal oxide film into a transition metal disulfide film.

[0009] Additional embodiments of the invention relate to a method for forming a transition metal disulfide film on a substrate surface comprising at least one feature. This method includes sequentially exposing the substrate surface to a metal precursor and an oxidant to directly deposit a transition metal oxide film. The metal precursor comprises bis(t-butylimino)bis(dimethylamino)tungsten or bis(t-butylimino)bis(dimethylamino)molybdenum. The transition metal oxide film is substantially conformally conformal over the at least one feature. The transition metal oxide film is exposed to a chalcogenide precursor to convert the transition metal oxide film into a transition metal disulfide film. The chalcogenide precursor comprises H₂S, and the transition metal disulfide film has a thickness in the range of 20 Å to 30 Å. The substrate surface is maintained at a temperature in the range of about 350 °C to about 450 °C. Simple Explanation of the Diagram

[0010] By referring to the embodiments, some of which are illustrated in the accompanying drawings, a more specific description of the invention briefly summarized above can be obtained, so that the foregoing features of the invention can be understood in detail in this manner. However, it will be noted that the accompanying drawings illustrate only typical embodiments of the invention and are therefore not to be regarded as limiting the scope of the invention, as the invention allows for other equivalent embodiments.

[0011] Figure 1 illustrates a cross-sectional view of a substrate according to one or more embodiments of the present invention;

[0012] Figure 2 illustrates a cross-sectional view of a substrate according to one or more embodiments of the present invention; and

[0013] Figure 3 illustrates a process flow diagram of a method according to one or more embodiments of the present invention. Implementation

[0014] Before describing several exemplary embodiments of the present invention, it will be understood that the invention is not limited to the details of the architecture or processing steps described in the following description. The invention can be other embodiments and can be implemented or performed in various ways.

[0015] As used in this specification and the accompanying claims, the term "substrate" refers to a surface or portion thereof on which processing is performed. Unless the context clearly indicates otherwise, those skilled in the art will understand that "substrate" may also refer to only a portion of a substrate. Furthermore, "deposition on a substrate" may mean both a bare substrate and a substrate having one or more films or features deposited or formed thereon.

[0016] When used here, the term "substantially oxygen-free" means that the transition metal disulfide film contains less than or equal to about 5% on an atomic basis, including less than or equal to about 4%, less than or equal to about 3%, less than or equal to about 2%, less than or equal to about 1%, and less than or equal to about 0.5% oxygen.

[0017] "Substrate" may include materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. The substrate is not limited to semiconductor wafers. The substrate may be exposed to pretreatment processes such as polishing, etching, reduction, oxidation, hydroxylation, annealing, UV curing, electron beam curing, and / or baking of the substrate surface. In addition to film treatments directly on the surface of the substrate itself, any film treatment steps disclosed in this invention may also be performed over an underlying layer formed on the substrate, as described in more detail below, and the term "substrate surface" is intended to include this underlying layer as indicated by the context. Thus, for example, where a film / layer or a portion of a film / layer has been deposited onto the substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0018] When used herein, "substrate surface" refers to any substrate surface on which layers may be formed. This substrate surface may have one or more features formed thereon, one or more layers formed thereon, and combinations thereof. Prior to the disclosed method, this substrate (or substrate surface) may be pretreated, for example by polishing, etching, reduction, oxidation, halogenation, hydroxylation, annealing, baking, or similar treatments.

[0019] This substrate can be any substrate capable of having materials deposited thereon, such as silicon substrates, III-V compound substrates, silicon-germanium (SiGe) substrates, epitaxial substrates, silicon-on-insulator (SOI) substrates, display substrates such as liquid crystal displays (LCDs), plasma displays, electroluminescent (EL) lamp displays, solar arrays, solar panels, light-emitting diode (LED) substrates, semiconductor wafers, or the like. In some embodiments, one or more additional layers may be disposed on this substrate such that a transition metal disulfide layer may be at least partially formed thereon. For example, in some embodiments, a layer comprising a metal, nitride, oxide, or the like, or a combination of the foregoing, may be disposed on this substrate and such that a transition metal disulfide layer may be formed on or over this layer.

[0020] According to one or more embodiments, the term "above" for a film or a layer of a film includes the film or layer directly on a surface, such as a substrate surface, and has one or more underlying layers between the film or layer and the surface, such as the substrate surface. Therefore, in one or more embodiments, the phrase "above a substrate surface" is intended to include one or more underlying layers. In other embodiments, the phrase "directly above" refers to a layer or film in contact with a surface, such as a substrate surface, without an intermediate layer. Therefore, the phrase "directly above a substrate surface" refers to a layer in direct contact with a substrate surface without any intermediate layers.

[0021] According to one or more embodiments, the disclosed method utilizes atomic layer deposition (ALD) processing. In such embodiments, the substrate surface is sequentially exposed to a precursor (or reactive gas). As used in this specification, "sequentially" means that the period of precursor exposure does not intentionally overlap with exposure to the co-reactant in a manner intended to create a gas-phase reaction. It is understood that although some overlap may occur, this overlap is unintentional.

[0022] When used in this specification and the accompanying claims, the terms "precursor," "reactant," "reacting gas," and the like are used interchangeably to refer to any gaseous species that can react with the substrate surface.

[0023] As used herein, "atomic layer deposition" or "cyclic deposition" refers to the sequential exposure of two or more reactive compounds to deposit a material layer on a substrate surface. When used in this specification and the accompanying claims, the terms "reactive compound," "reactive gas," "reactive species," "precursor," "processing gas," and the like may be used interchangeably to refer to a substance having a species capable of reacting with the substrate surface or with materials on the substrate surface during surface reactions (e.g., chemisorption, oxidation, reduction). The substrate or portions thereof are sequentially exposed to two or more reactive compounds introduced into a reaction region of a processing chamber. In time-domain ALD processing, exposure to each reactive compound is separated by a time delay to allow each compound to adhere to and / or react on the substrate surface. In spatial ALD processing, different portions of the substrate surface, or materials on the substrate surface, are simultaneously exposed to two or more reactive compounds such that any given point on the substrate is substantially exposed to only one reactive compound at any given time. When used in this specification and the accompanying claims, as will be understood by one of ordinary skill in the art, the term "substantially" as used herein means the possibility that a small portion of the substrate may be simultaneously exposed to multiple reactive gases due to diffusion, and that such simultaneous exposure is not intentional.

[0024] In a time-domain ALD process, a first reactant gas (i.e., a first precursor or compound A) is pulsed into the reaction region, followed by a first time delay. Next, a second precursor or compound B is pulsed into this reaction region, followed by a second delay. During each time delay, a purge gas, such as argon, is introduced into the processing chamber to purge the reaction region or remove any residual reactant compounds or byproducts. Alternatively, the purge gas may flow continuously throughout the deposition process, such that only the purge gas flows during the time delay between pulses of the reactant compounds. The reactant compounds are pulsed alternately until the desired film or film thickness is formed on the substrate surface.

[0025] In some embodiments, the pulsed compound A, purge gas, compound B, and ALD treatment of the purge gas constitute a cycle. A cycle may be initiated by compound A or compound B and continue in individual sequences until a film of desired thickness is achieved. In some embodiments, two reactants, A and B, may be alternately pulsed and purged.

[0026] In some embodiments, three or more reactants, A, B, and C, may be alternately pulsed and purged. In some embodiments, each reactant is utilized during each deposition cycle (e.g., ABC). In some embodiments, a series of alternating exposures to compounds A and B (e.g., ABABC) may be performed prior to exposure to compound C.

[0027] In the spatial ALD process, a first reactant gas and a second reactant gas are delivered simultaneously to the reaction zone, but separated by an inert gas curtain and / or a vacuum curtain. The substrate moves relative to the gas delivery device, such that any given point on the substrate is exposed to both the first and second reactant gases.

[0028] Embodiments of the present invention provide a method for forming a transition metal disulfide film for use as a channel material, pad, or barrier layer in the miniaturization and scaling up of integrated circuits. In one or more embodiments, the transition metal disulfide film serves as a barrier or pad in 3D NAND applications. For example, a transition metal disulfide film as a barrier / pad can facilitate the nucleation of subsequently deposited metals, adhesively bond metals to the underlying dielectric material, and prevent metal elements from diffusing into the underlying dielectric material.

[0029] In one or more embodiments, transition metal disulfide films serve as channel materials in 3D NAND applications. In one or more embodiments, as an example, transition metal disulfide films exhibit superior carrier mobility compared to polycrystalline silicon. The carrier mobility of transition metal disulfide films can improve the performance of 3D NAND devices.

[0030] Embodiments of the present invention provide a low thermal budget method to achieve high-quality 2D transition metal dichalcogenide films for use in temperature-sensitive device architectures.

[0031] Referring to Figure 1, a substrate 100 comprising a base material 110 is shown having at least one feature 120 formed of a material 130. In some embodiments, the base material 110 and the material 130 are the same. In some embodiments, the base material 110 is a metal or other conductive material. In some embodiments, the material 130 is a dielectric. The figure shows a substrate having three features for illustration; however, those skilled in the art will understand that it may have more or fewer than three features. In one or more embodiments, the substrate 100 includes at least one feature 120.

[0032] The shape of feature 120 can be any suitable shape, including but not limited to trenches and cylindrical through-holes. When used in this context, the term "feature" means any intentional surface irregularity. Suitable examples of features include, but are not limited to, trenches having two sidewalls and a bottom, and peaks having a top and two sidewalls. Features can have any suitable aspect ratio (height / depth to width ratio). In some embodiments, the aspect ratio is greater than or equal to about 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, or 40:1. In one or more embodiments, at least one feature 120 is a trench. In one or more embodiments, at least one feature 120 is a dielectric material and a conductive material. In one or more embodiments, a transition metal oxide film (not shown) is selectively formed on the dielectric material.

[0033] Referring to Figure 2, each of at least one feature 120 has a transition metal disulfide film 140 deposited thereon. In one or more embodiments, the substrate 100 includes a metal filler 150 deposited on the transition metal disulfide film 140 in each of the at least one feature 120. In one or more embodiments, the metal filler 150 comprises a highly conductive metal. In some embodiments, the metal filler 150 comprises one or more of copper (Cu), cobalt (Co), tungsten (W), molybdenum (Mo), or ruthenium (Ru).

[0034] Embodiments of the present invention relate to a method for forming a transition metal disulfide film. In one or more embodiments, the method of depositing this film includes forming a transition metal oxide film on a substrate surface and subsequently converting the transition metal oxide film into a transition metal disulfide film.

[0035] In some embodiments, the transition metal oxide film is formed directly without forming a transition metal film intermediate. The inventors have unexpectedly discovered that forming a specific metal (e.g., tungsten) on the dielectric layer is more difficult than forming a metal oxide (e.g., longer processing time, increased temperature). Furthermore, the subsequent formation of the oxidized metal layer requires even more processing time and reduces throughput. Therefore, some embodiments of the invention advantageously provide a method for forming a transition metal oxide film without forming a metal film intermediate.

[0036] In some embodiments, the substrate surface does not contain a barrier layer. Not limited by theory, it is believed that the formation of a metal layer without a barrier layer would lead to potential diffusion of metal into the underlying material. The inventors have unexpectedly discovered that diffusion from the metal oxide material is significantly low. In some embodiments, the diffusion of metal atoms from the metal oxide material is low enough that the benefits of the barrier layer are negligible. Therefore, eliminating the barrier layer from the processing flow is expected to reduce processing time, increase yield, and reduce the resistance of the metal fill, which would be larger in volume.

[0037] In one or more embodiments, a hot Ar / H₂S or H₂ / H₂S gas is used to sulfidate the transition metal oxide film. In one or more embodiments, a plasma formed from Ar / H₂S or H₂ / H₂S gas is used to sulfidate the transition metal oxide film. In one or more embodiments, by one or more of the sulfidation treatments described herein, a transition metal oxide film having tungsten (W) is converted into WS₂.

[0038] In one or more embodiments, the conversion of transition metal oxide films into transition metal disulfide films is performed at plasma power ranging from 25 watts (W) to 500 watts (W).

[0039] In one or more embodiments, after forming a transition metal oxide film having a thickness in the range of 10 Å to 50 Å, or in the range of 15 Å to 35 Å, 15 Å to 25 Å, or 20 Å to 30 Å, the transition metal oxide film is converted into a transition metal disulfide film. In some embodiments, after forming one monolayer, one to five monolayers, or one to ten monolayers of transition metal oxide, the transition metal oxide film is converted into a transition metal disulfide film.

[0040] In one or more embodiments, the method further includes repeatedly forming a transition metal oxide film and converting the transition metal oxide film to form a transition metal disulfide film having a final thickness of up to 200 Å. In one or more embodiments, the transition metal disulfide film has a final thickness of up to 150 Å, up to 100 Å, or up to 50 Å. In some embodiments, the transition metal disulfide film has a final thickness in the range of 20 Å to 30 Å.

[0041] In one or more embodiments, the conversion of a transition metal oxide film into a transition metal disulfide film is performed at a temperature ranging from about 350 °C to about 500 °C. In some embodiments, the conversion of a transition metal oxide film into a transition metal disulfide film is performed at a pressure ranging from 1 Torr to 20 Torr, 1 Torr to 10 Torr, 5 Torr to 20 Torr, or 5 Torr to 10 Torr.

[0042] In one or more embodiments, the conversion of a transition metal oxide film into a transition metal disulfide film is performed for a period ranging from 30 minutes to 60 minutes. In one or more embodiments, the conversion of the transition metal oxide film into a transition metal disulfide film comprises exposing the transition metal oxide film to a chalcogenide precursor comprising one or more of sulfur (S), selenium (Se), or tellurium (Te). In some embodiments, the chalcogenide precursor comprises H₂S.

[0043] Referring to Figure 3, one or more embodiments of the present invention relate to a method 200 for forming a transition metal disulfide film. The method illustrated in Figure 3 is representative of atomic layer deposition (ALD) processing, wherein the substrate or substrate surface is sequentially exposed to the reactive gases in a manner that prevents or minimizes the gas-phase reaction of the reactive gases. In this way, this method avoids chemical vapor deposition (CVD) processing, in which the reactive gases are mixed in a processing chamber to allow for the gas-phase reaction of the reactive gases.

[0044] In one or more embodiments of the invention, method 200 includes optionally pre-treating the substrate in operation 205. A transition metal disulfide film is formed in deposition cycle 210. Deposition cycle 210 can be understood as having two stages 220 and 230. The first stage 220, including operations 222, 224, 226, and 228, forms a transition metal oxide film on the substrate surface. The second stage 230, including operations 232 and 234, converts the transition metal oxide film into a transition metal disulfide film.

[0045] In some embodiments, the second stage 230 is performed after a transition metal oxide film of a predetermined thickness has been deposited in the first stage 220. In some embodiments, the second stage 230 is performed after a single operation of the first stage 220. In some embodiments, the second stage 230 is performed after multiple cycles of the first stage 220.

[0046] The first stage 220 includes sequential exposure of the substrate to a transition metal precursor in operation 212, optional cleansing of the substrate surface in operation 214, exposure of the substrate to an oxidant in operation 216, and optional cleansing of the substrate surface in operation 218.

[0047] The second stage 230 includes sequential exposure of the substrate in operation 232 to chalcogenide precursors and optional cleansing of the substrate surface in operation 234.

[0048] In some embodiments, method 200 optionally includes a pretreatment operation 205. The pretreatment can be any suitable pretreatment known to those skilled in the art. Suitable pretreatments include, but are not limited to, preheating, cleaning, soaking, removal of native oxides, or deposition of an adhesive / barrier layer (e.g., titanium nitride (TiN)). In one or more embodiments, an adhesive layer such as titanium nitride is deposited in operation 205. In some embodiments, as described above, the substrate surface does not contain a barrier layer. In one or more embodiments, optional pretreatment operation 205 includes flowing plasma gas comprising one or more of the following: Ar / O2, Ar / H2, or Ar / H2S followed by Ar / H2.

[0049] Regarding the first stage 220 of deposition cycle 210, in one or more embodiments, during operation 222, the substrate (or substrate surface) is exposed to a metal precursor to form reactive metal species on the substrate surface. The transition metal precursor may be any suitable transition metal-containing compound that can react with the substrate surface (i.e., adsorb or chemisorb onto the substrate surface) to leave transition metal-containing species on the substrate surface.

[0050] In one or more embodiments, the metal precursor comprises one or more of tungsten, molybdenum, tantalum, titanium, or ruthenium. In some embodiments, the metal precursor does not contain oxygen or halogen atoms. In some embodiments, the metal precursor comprises or is substantially composed of one or more of bis(t-butylimino)bis(dimethylamino)tungsten or bis(t-butylimino)bis(dimethylamino)molybdenum.

[0051] In operation 224, the processing chamber or substrate surface is optionally cleaned to remove unreacted metal precursors, reaction products, and byproducts. When used in this manner, the term "processing chamber" also includes the portion of the processing chamber adjacent to the substrate surface but does not encompass the entire internal volume of the processing chamber. For example, in a spatially separated section of the processing chamber, the portion of the processing chamber adjacent to the substrate surface is cleaned of transition metal oxide precursors by any suitable technique, including but not limited to moving the substrate through an air curtain to a portion or section of the processing chamber that does not contain or is substantially free of metal precursors.

[0052] In one or more embodiments, the purification chamber includes the application of a vacuum. In some embodiments, the purification chamber includes the flow of a purification gas across a substrate. In some embodiments, this portion of the purification chamber refers to a micro-volume or small-volume processing station within the purification chamber. The term "proximate" in relation to the substrate surface means that the physical space near the surface of the substrate provides sufficient space for surface reactions to occur (e.g., precursor adsorption). In one or more embodiments, the purification gas is selected from one or more of nitrogen (N₂), helium (He), and argon (Ar).

[0053] In operation 226, the substrate (or substrate surface) is exposed to an oxidant to form a transition metal oxide film on the substrate. The oxidant (also referred to as an oxide reactant) can be any suitable compound used to oxidize an adsorbed metal precursor to form the transition metal oxide film. In some embodiments, the oxidant comprises one or more of H₂O, O₂, or O₃. In some embodiments, the oxidant does not contain plasma. In some embodiments, the transition metal oxide film is stoichiometric. When used in this respect, a "stoichiometric" film has a metal:oxygen ratio within 95% of a generally acceptable stoichiometric ratio (e.g., WO₃).

[0054] In operation 228, after exposure to the chalcogenide reactants, the processing chamber is optionally cleaned. The cleaning of the processing chamber in operation 228 may be the same as or different from the cleaning in operation 224. Cleaning the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc., removes the oxidant (oxide reactants), reaction products, and byproducts from areas adjacent to the substrate surface. In one or more embodiments, in operation 228, the processing chamber is optionally cleaned after exposure to the oxidant.

[0055] In decision 229, the thickness of the transition metal oxide film or the number of cycles of the precursor and oxidant are considered. If the transition metal oxide film has reached a predetermined thickness or a predetermined number of processing cycles have been performed, method 200 moves to the second stage 230. If the thickness of the transition metal oxide film or the number of processing cycles has not reached a predetermined threshold, method 200 returns to operation 222 to repeat the first stage 220. As identified above, in some embodiments, the transition metal oxide film may be formed to a predetermined thickness in the first stage 220 before being converted to transition metal disulfide in the second stage 230. In some embodiments, a predetermined number of monolayers (as few as 1) of the transition metal oxide film may be formed before being converted to transition metal disulfide in the second stage 230.

[0056] In the second stage 230, the transition metal oxide film formed in the first stage 220 is converted into a transition metal disulfide film. In some embodiments, the conversion of the transition metal oxide film includes operation 232 exposing the transition metal oxide film to a chalcogenide precursor. The chalcogenide precursor comprises one or more of S, Se, or Te. In some embodiments, the chalcogenide precursor comprises H₂S. In some embodiments, the chalcogenide precursor further comprises H₂. In some embodiments, the chalcogenide precursor does not contain plasma.

[0057] In operation 234, the processing chamber or substrate surface may be cleaned. The inventors have found that cleaning the processing chamber in operation 234 is particularly appropriate if returning to the first stage 220 to deposit an additional transition metal oxide film. Without being limited by theory, it is believed that the cleanup in operation 234 provides a "clean" substrate surface, which enhances the adsorption of metal precursors in operation 222. In other respects, the description of the cleanup performed in operation 224 or operation 228 (in both operation and composition) also applies to operation 234.

[0058] In one or more embodiments, the deposited film is substantially oxygen-free. As used herein, "substantially oxygen-free" means that the transition metal disulfide film contains less than or about 5% oxygen on an atomic basis, including less than or equal to about 4%, less than or equal to about 3%, less than or equal to about 2%, less than or equal to about 1%, or less than or equal to about 0.5%. Therefore, without being theoretically limited, it is contemplated that the transition metal disulfide film is formed without generating oxygen as a byproduct, thus minimizing the possibility of etching / corrosion of the underlying metal layer.

[0059] In step 240, the thickness of the transition metal disulfide film or the number of cycles in deposition cycle 210 is determined. If the transition metal disulfide film has reached a predetermined thickness or the predetermined number of cycles has been performed, method 200 proceeds to an optional post-processing operation 250. If the thickness of the transition metal disulfide film or the number of cycles has not yet reached a predetermined threshold, method 200 returns to operation 210 to form an additional transition metal disulfide film.

[0060] Optional post-treatment operation 250 may be, for example, a treatment to modify membrane properties (e.g., annealing) or a further membrane deposition treatment (e.g., additional ALD or CVD treatment) to grow additional membranes.

[0061] Method 200 can be performed at any suitable temperature, depending on factors such as the metal precursor, oxidant, chalcogenide reactant, or the thermal budget of the device. In one or more embodiments, high-temperature processing is not desirable for temperature-sensitive substrates such as logic devices. The method of claim 1, wherein the substrate surface is maintained at a temperature in the range of about 350 °C to about 450 °C or about 300 °C to about 500 °C.

[0062] In some embodiments, exposure to a transition metal precursor or a metal precursor (operation 212) occurs at a different temperature than exposure to an oxidant (operation 226) or a chalcogenide precursor (operation 232). In some embodiments, the substrate is maintained at a first temperature in the range of 300 °C to 400 °C for exposure to the metal precursor and / or oxidant, and at a second temperature in the range of 400 °C to 450 °C for exposure to the chalcogenide precursor. In some embodiments, both the metal precursor and the chalcogenide precursor are delivered at the same substrate temperature.

[0063] One or more embodiments of the present invention relate to a method for depositing a transition metal disulfide film in a high aspect ratio feature. The high aspect ratio feature is a trench, via, or pillar having a height:width ratio greater than or equal to about 10, 20, or 50, or greater. In some embodiments, the transition metal film is conformally deposited on the high aspect ratio feature. When used in this manner, the conformal film has a thickness near the top of the feature that is in the range of about 90-110% of the thickness at the bottom of the feature.

[0064] According to one or more embodiments, the substrate is processed before and / or after the formation of the layer. This processing can be performed in the same chamber or in one or more separate processing chambers. In some embodiments, the substrate is moved from a first chamber to a separate second chamber for further processing. The substrate can be moved directly from the first chamber to the separate processing chamber, or it can be moved from the first chamber to one or more transfer chambers and then to the separate processing chambers. Thus, the processing apparatus may include multiple chambers connected by transfer stations. Such an apparatus may be referred to as a "clustering tool" or "clustering system," and the like.

[0065] Generally, a clustering tool is a modular system comprising multiple chambers that performs various functions, including substrate centering and orientation, degassing, annealing, deposition, and / or etching. According to one or more embodiments, the clustering tool includes at least a first chamber and a central transfer chamber. The central transfer chamber houses a robot that allows the substrate to move between and within the processing chamber and the loading gate chamber. The transfer chamber is typically maintained under vacuum and provides an intermediate stage for moving the substrate from one chamber to another and / or to the loading gate positioned at the front end of the clustering tool. Two well-known clustering tools that can be used in this invention are Centura® and Endura®, both available from Applied Materials, Santa Clara, California. However, the exact arrangement and combination of the chambers can be varied to perform the specific steps described herein. Other processing chambers that can be used include, but are not limited to, circulating layer deposition (CLD), atomic layer deposition (ALD), chemical phase deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, chemical cleaning, thermal processing such as RTP, plasma nitriding, degassing, orientation, hydroxylation, and other substrate treatments. By performing the processing in a chamber on a cluster tool, surface contamination of the substrate by atmospheric impurities can be avoided, as well as oxidation before the deposition of subsequent films.

[0066] According to one or more embodiments, the substrate is continuously under vacuum or in a "loading gate" state and not exposed to ambient air as it moves from one chamber to the next. The transfer chamber is therefore under vacuum and is "pumped back" under vacuum pressure. An inert gas may be present in the processing chamber or the transfer chamber. In some embodiments, the inert gas is used as a purge gas to remove some or all of the reactants (e.g., reactants). According to one or more embodiments, the purge gas is injected at the outlet of the deposition chamber to prevent reactants (e.g., reactants) from moving from the deposition chamber to the transfer chamber and / or additional processing chambers. Thus, the flow of the inert gas forms a curtain at the outlet of the chamber.

[0067] Substrates can be processed in a single substrate deposition chamber, wherein a single substrate is loaded, processed, and unloaded before another substrate is processed. Substrates can also be processed continuously, similar to a conveyor belt system, wherein multiple substrates are individually loaded into a first portion of the chamber, move through the chamber, and are unloaded from a second portion of the chamber. The shapes of the chambers and the associated conveyor belt system can form straight or curved paths. Furthermore, the processing chamber can be a rotating rack, in which multiple substrates move about a central axis and are exposed to deposition, etching, annealing, cleaning, and other processes through the rotating rack path.

[0068] During processing, the substrate may be heated or cooled. This heating or cooling can be accomplished by any suitable means, including but not limited to changing the temperature of the substrate support and flowing heating or cooling gas to the substrate surface. In some embodiments, the substrate support includes a heater / cooler that can be controlled to conductively change the substrate temperature. In one or more embodiments, the gas used (reactive gas or inert gas) is heated or cooled to locally change the substrate temperature. In some embodiments, the heater / cooler is positioned within a chamber adjacent to the substrate surface to convectively change the substrate temperature.

[0069] The substrate can be stationary or rotated during processing. A rotating substrate can be rotated continuously or intermittently (about its axis). For example, the substrate can be rotated throughout the entire process, or it can be rotated slightly between exposures to different reactive or purge gases. Rotating the substrate (continuously or intermittently) during processing can help produce more uniform deposition or etching by minimizing the effects of local variability, such as in gas flow geometry.

[0070] Spatial relative terms such as “below,” “under,” “lower,” “above,” “above,” and similar expressions are used here to simplify descriptions of the relationship between one element or feature and another, as illustrated in the figures. It will be understood that spatial relative terms are intended to cover different orientations of the device in use or operation, in addition to those depicted in the figures. For example, if the device in the figures is inverted, an element described as “below” or “under” another element or feature will be oriented “above” that element or feature. Therefore, the exemplary term “below” can encompass both the orientations above and below. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial relative descriptors used herein will be interpreted accordingly.

[0071] In the context of describing the materials and methods discussed herein (particularly in the context of the accompanying claims), the use of the terms "a" and "an," "the," and similar indicative terms is intended to construct and cover both the singular and plural, unless otherwise specified herein or clearly contradicted by the context. Numerical ranges mentioned herein are intended only as shorthand for each separate numerical value falling within the range, unless otherwise specified herein, and each separate numerical value is incorporated herein as if it were individually mentioned herein. All methods described herein may be performed in any suitable order, unless otherwise specified herein or clearly contradicted by the context. The use of any and all example or exemplary language (e.g., "such as") provided herein is intended only to better illustrate the materials and methods and does not impose limitations on the scope, unless otherwise stated. No language in this specification should be construed as indicating that any non-stated element is necessary for the disclosed materials and methods.

[0072] Throughout this specification, references to "one embodiment," "some embodiments," "one or more embodiments," or "an embodiment" indicate that a particular feature, structure, material, or characteristic described with respect to that embodiment is included in at least one embodiment of the invention. Therefore, the appearance of phrases such as "in one or more embodiments," "in some embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification does not necessarily refer to the same embodiment of the invention. Furthermore, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0073] Although the invention has been described herein with reference to specific embodiments, those skilled in the art will understand that these embodiments are merely illustrative of the principles and applications of the invention. Various modifications and variations of the methods and apparatus of the invention can be made without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art. Therefore, the invention may include modifications and variations falling within the scope of the appended claims and their equivalents.

[0074] 100:Substrate 110: Substrate material 120: Features 130: Materials 140: Transition metal disulfide film 150: Metal Filler 200: Method 205: Operation 210: Deposition Processing Cycle 220: Phase One 222: Operation 224: Operation 226: Operation 228: Operation 229:Judgment 230: Second Phase 232: Operation 234: Operation 240:Judgment 250: Post-processing operations

[0075] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A method for forming a transition metal disulfide film, the method comprising the steps of: depositing a transition metal oxide film on a substrate surface by sequentially exposing a substrate surface to a metal precursor, a purge gas, an oxidant and the purge gas, the oxidant comprising one or more of H2O, O2, or O3; and converting the transition metal oxide film into the transition metal disulfide film, wherein the transition metal disulfide film is a channel material in a 3D NAND device, and the method is a thermal method performed without plasma.

2. The method as described in claim 1, wherein the surface of the substrate does not contain a barrier layer.

3. The method as described in claim 1, wherein the substrate surface is maintained at a temperature in the range of about 350 °C to about 450 °C.

4. The method as described in claim 1, wherein the surface of the substrate comprises a dielectric material.

5. The method as described in claim 1, wherein the substrate surface includes at least one feature having an aspect ratio greater than or equal to about 10:

1.

6. The method as described in claim 1, wherein the step of depositing the transition metal oxide film comprises the following steps: directly forming the transition metal oxide film without forming a transition metal film intermediate.

7. The method as described in claim 1, wherein the metal precursor does not contain oxygen or halogen atoms.

8. The method as claimed in claim 1, wherein the metal precursor comprises bis(t-butylimino)bis(dimethylamino)tungsten or bis(t-butylimino)bis(dimethylamino)molybdenum.

9. The method as described in claim 1, wherein the step of converting the transition metal oxide film is performed at a pressure ranging from 5 Torr to 20 Torr.

10. The method of claim 1, wherein the step of converting the transition metal oxide film into the transition metal disulfide film comprises the following steps: exposing the transition metal oxide film to a chalcogenide precursor, the chalcogenide precursor comprising one or more of sulfur (S), selenium (Se) or tellurium (Te).

11. The method as described in claim 10, wherein the chalcogenide precursor comprises H2S.

12. The method as described in claim 1, wherein a transition metal oxide film of 20 Å to 30 Å is formed before the transition metal oxide film is converted.

13. The method as described in claim 1, wherein only a single layer of the transition metal oxide film is formed before the transition metal oxide film is converted.

14. The method as described in claim 13, wherein the method is repeated to form the transition metal dichalcogenide film to a thickness in the range of 20 Å to 30 Å.

15. The method as described in claim 1, wherein the transition metal disulfide film is substantially oxygen-free.

16. The method of claim 1, wherein the substrate surface includes at least one feature and the transition metal dichalcogenide film is substantially conformally formed over the at least one feature.

17. The method of claim 1, wherein the steps of depositing the transition metal oxide film on the substrate surface and converting the transition metal oxide film into the transition metal disulfide film are performed in a single processing chamber.

18. A method for forming a transition metal disulfide film on the surface of a substrate comprising at least one feature, the method comprising the steps of: sequentially exposing the substrate surface to a metal precursor, a purge gas, an oxidant, and the purge gas to directly deposit a transition metal oxide film, the metal precursor comprising bis(t-butylimino)bis(dimethylamino)tungsten or bis(t-butylimino)bis(dimethylamino)molybdenum, the transition metal oxide film being substantially conformally constitutive over the at least one feature; exposing the transition metal oxide film to a chalcogenide precursor to convert the transition metal oxide film into the transition metal disulfide film, the chalcogenide precursor comprising H2S, wherein the conversion step of the transition metal oxide film is performed at a pressure of 1 Torr, the transition metal disulfide film being a channel material in a 3D NAND device and having a 20 A thickness in the range of Å to 30 Å, the substrate surface is maintained at a temperature in the range of about 350 °C to about 450 °C, and the method is a thermal method performed without plasma.

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