Conformal metal dichalcogenides

Abstract

Transition metal dichalcogenide films and methods for depositing transition metal dichalcogenide films on a substrate are described. Methods for converting transition metal oxide films to transition metal dichalcogenide films are also described. Exposing the substrate to a metal precursor and an oxidizing agent to form a transition metal oxide film; the transition metal oxide film is exposed to a chalcogenide precursor to form a transition metal dichalcogenide film.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to methods of forming transition metal dichalcogenides (TMDCs). In particular, embodiments of the present disclosure are directed to methods of forming TMDC films for memory and logic applications. Background Art

[0002] The semiconductor processing industry is continually striving to achieve greater yields while improving the uniformity of layers deposited on substrates with larger surface areas. These same factors combined with new materials also provide for higher circuit integration per unit area of ​​the substrate. As circuit integration increases, the need for greater uniformity and process control related to layer thickness also increases. Therefore, various techniques have been developed to deposit layers on substrates in a more cost-effective manner while maintaining control over the layer properties.

[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 precursors introduced into the processing chamber in order to produce a uniform thickness of the desired layer. These requirements become more critical as substrate size increases, requiring more complex chamber design and gas flow techniques to maintain adequate uniformity.

[0004] One CVD variant that exhibits excellent step coverage is cyclic deposition or atomic layer deposition (ALD). Cyclic deposition is based on atomic layer epitaxy (ALE) and employs a chemical adsorption technique to deliver precursor molecules on a substrate surface in sequential cycles. The cycle exposes the substrate surface to a first precursor, a purge gas, a second precursor, and a purge gas. The first and second precursors react to form a product compound as a film on the substrate surface. The cycle is repeated to form the layer to a desired thickness.

[0005] The increasing complexity of advanced microelectronic components places stringent demands on currently used deposition techniques. Unfortunately, there are a limited number of viable chemical precursors available that have the necessary properties of robust thermal stability, high reactivity, and vapor pressure suitable for film growth to occur.

[0006] Transition metal dichalcogenides (TMDCs) are known to be ideal candidates for alleviating metal migration issues associated with scaling down of film interconnects. In addition, TMDCs have better conductivity and carrier mobility compared to current processes in 3D NAND devices. Recent TMDC approaches require high temperature processes that may be incompatible with device thermal budgets.

[0007] Therefore, there is a need for a conformal TMDC that can be grown by a low-temperature thermal process suitable for device integration in temperature-sensitive structures. Summary of the invention

[0008] One or more embodiments of the present disclosure are directed to a method for forming a transition metal dichalcogenide film, which includes depositing a transition metal oxide film on a substrate surface; and converting the transition metal oxide film into a transition metal dichalcogenide film.

[0009] Additional embodiments of the present disclosure are directed to a method of forming a transition metal dichalcogenide film on a substrate surface including at least one feature. The 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 includes bis(tert-butylimino)bis(dimethylamino)tungsten or bis(tert-butylimino)bis(dimethylamino)molybdenum. The transition metal oxide film is substantially 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 dichalcogenide film. The chalcogenide precursor includes H2S, and the transition metal dichalcogenide film has a transition metal oxide film having ... to The substrate surface is maintained at a temperature in the range of about 350°C to about 450°C.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order that the manner in which the above-described features of the present disclosure may be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be obtained by reference to the embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only typical embodiments of the present disclosure and are therefore not to be considered limiting of the scope of the present disclosure, as the disclosure may admit to other equally effective embodiments.

[0012] Figure 1 depicts a cross-sectional view of a substrate according to one or more embodiments of the present disclosure;

[0013] Figure 2 depicts a cross-sectional view of a substrate according to one or more embodiments of the present disclosure;

[0014] Figure 3A process flow diagram illustrating a method according to one or more embodiments of the present disclosure; and

[0015] Figure 4 A cross-sectional view of a substrate according to one or more embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0016] Before describing several exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of construction or process steps set forth in the following description. The present disclosure is capable of other embodiments and can be practiced or carried out in various ways.

[0017] As used in this specification and the appended claims, the term "substrate" refers to a surface, or a portion of a surface, on which a process acts. Those skilled in the art will also understand that references to a substrate may also refer to only a portion of a substrate unless the context clearly indicates otherwise. In addition, references to depositing on a substrate may mean a bare substrate and a substrate having one or more films or features deposited or formed thereon.

[0018] As used herein, the term "substantially free of oxygen" means that there is less than or equal to about 5% oxygen, 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, on an atomic basis, in the transition metal dichalcogenide film.

[0019] Depending on the application, a "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 material such as metals, metal nitrides, metal alloys, and other conductive materials. Substrates include, but are not limited to, semiconductor wafers. The substrate may be exposed to a pretreatment process to grind, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure, and / or bake the substrate surface. In addition to performing film processing directly on the surface of the substrate itself, in the present disclosure, any of the disclosed film processing steps may also be performed on an underlying layer formed on the substrate (as disclosed in more detail below), and the term "substrate surface" is intended to include such an underlying layer, as indicated by the context. Thus, for example, where a film / layer or portion of a film / layer has been deposited onto a substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0020] As used herein, "substrate surface" refers to any substrate surface on which a layer can be formed. The substrate surface can have one or more features formed therein, one or more layers formed thereon, and combinations thereof. The substrate (or substrate surface) can be pre-treated prior to the disclosed methods, for example, by grinding, etching, reducing, oxidizing, halogenating, hydroxylating, annealing, baking, or the like.

[0021] The substrate may be any substrate capable of having a material deposited thereon, such as a silicon substrate, a III-V compound substrate, a silicon germanium (SiGe) substrate, an epitaxial substrate, a silicon-on-insulator (SOI) substrate, a display substrate (such as a liquid crystal display (LCD), a plasma display, an electroluminescence (EL) lamp display), a solar array, a solar panel, a light emitting diode (LED) substrate, a semiconductor wafer, or the like. In some embodiments, one or more additional layers may be disposed on the substrate such that a transition metal dichalcogenide layer may be at least partially formed thereon. For example, in some embodiments, a layer including a metal, a nitride, an oxide, or the like, or a combination thereof, may be disposed on the substrate and a transition metal dichalcogenide layer may be formed on this layer or layers.

[0022] According to one or more embodiments, the term "on..." with respect to a film or film layer includes the film or layer being directly on a surface (e.g., a substrate surface) and the presence of one or more bottom layers between the film or layer and the surface (e.g., a substrate surface). Thus, in one or more embodiments, the phrase "on a substrate surface" is intended to include one or more bottom layers. In other embodiments, the phrase "directly on..." represents that the layer or film is in contact with a surface (e.g., a substrate surface) with no intervening layers. Thus, the phrase "a layer is directly on a substrate surface" represents that the layer is in direct contact with the substrate surface with no layers in between.

[0023] According to one or more embodiments, the disclosed methods utilize an atomic layer deposition (ALD) process. In these embodiments, the substrate surface is exposed to the precursors (or reactive gases) sequentially. As used herein throughout this specification, "sequentially" means that the duration of the precursor exposure does not intentionally overlap with the exposure of the auxiliary reagent in a manner intended to produce a gas phase reaction. It should be understood that although some overlap may occur, this overlap is unintentional.

[0024] As used in this specification and the appended claims, the terms "precursor," "reactant," "reactive gas," and similar terms are used interchangeably to represent any gaseous species that can react with a substrate surface.

[0025] As used herein, "atomic layer deposition" or "cyclic deposition" refers to the sequential exposure of two or more reactive compounds to deposit a layer of material on a substrate surface. As used in this specification and the appended claims, the terms "reactive compound," "reactive gas," "reactive species," "precursor," "process gas," and similar terms are used interchangeably to mean a substance having a species capable of reacting with a substrate surface or a material on a substrate surface in a surface reaction (e.g., chemical adsorption, oxidation, reduction). A substrate or portion of a substrate is sequentially exposed to two or more reactive compounds in a reaction zone introduced into a processing chamber. In a time-domain ALD process, the exposure to each reactive compound is separated by a time delay, allowing each compound to adhere and / or react on the substrate surface. In a spatial ALD process, 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 a time. As used in this specification and the appended claims, as will be understood by those skilled in the art, the term "substantially" used in this regard means that it is possible that a small portion of the substrate may be exposed to multiple reactive gases simultaneously due to diffusion, and that such simultaneous exposure is unintentional.

[0026] In one aspect of a time-domain ALD process, a first reactive gas (i.e., a first precursor or compound A) is pulsed into a reaction region followed by a first time delay. Next, a second precursor or compound B is pulsed into the 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 otherwise remove any residual reactive compounds or byproducts from the reaction region. 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 reactive compounds. The reactive compounds are pulsed alternately until a desired film or film thickness is formed on the substrate surface.

[0027] In some embodiments, the ALD process of pulsing compound A, purge gas, compound B, and purge gas is a cycle. The cycle can start with either compound A or compound B and continue in the corresponding order of the cycle until a film with a desired thickness is achieved. In some embodiments, the two reactants A and B can be pulsed and purged alternately.

[0028] In some embodiments, there may be three or more reactants A, B, and C that are alternately pulsed and purged. In some embodiments, each reactant (e.g., ABC) is utilized during each deposition cycle. 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.

[0029] In a spatial ALD process, a first reactive gas and a second reactive gas are delivered to a reaction region simultaneously, but separated by an inert gas curtain and / or a vacuum curtain. The substrate moves relative to the gas delivery device so that any given point on the substrate is exposed to both the first reactive gas and the second reactive gas.

[0030] Embodiments of the present disclosure provide methods for forming transition metal dichalcogenide films for use as channel materials, liners, or barrier layers in the miniaturization and scaling of integrated circuits. In one or more embodiments, the transition metal dichalcogenide film acts as a barrier or liner in 3D NAND applications. For example, the transition metal dichalcogenide film acting as a barrier / liner can enable nucleation of subsequently deposited metals, adhesively bond the metals to underlying dielectric materials, and prevent diffusion of metal elements into the underlying dielectric materials.

[0031] In one or more embodiments, the transition metal dichalcogenide film acts as a channel material in 3D NAND applications. In one or more embodiments, the transition metal dichalcogenide film has better carrier mobility than polysilicon, as an example. The carrier mobility of the transition metal dichalcogenide film can improve 3D NAND device performance.

[0032] Embodiments of the present disclosure provide a low thermal budget approach to achieve high quality 2D transition metal dichalcogenide films for temperature sensitive device architectures.

[0033] refer to Figure 1 , a substrate 100 is shown, which includes a base material 110 having at least one feature 120 formed of a material 130. The surfaces of the base material 110 and the material 130 form a substrate surface. 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 figures show a substrate with three features for illustrative purposes; however, those skilled in the art will understand that there may be more or less than three features. In one or more embodiments, the substrate 100 includes at least one feature 120.

[0034] The shape of the feature 120 may be any suitable shape, including but not limited to a groove and a cylindrical via. As used in this regard, the term "feature" means any intentional surface irregularity. Suitable examples of features include but are not limited to a groove having two sidewalls and a bottom, a peak having a top and two sidewalls, and a via having a bottom and a cylindrical or elliptical cylindrical sidewall. The feature may have any suitable aspect ratio (ratio of height / depth to width). 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, the at least one feature 120 is a groove. In one or more embodiments, the 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.

[0035] refer to Figure 2 , each of the at least one feature 120 has a transition metal dichalcogenide film 140 deposited thereon. In one or more embodiments, the substrate 100 includes a metal filler 150 deposited on the transition metal dichalcogenide film 140 in each of the at least one feature 120. In one or more embodiments, the metal filler 150 includes a highly conductive metal. In some embodiments, the metal filler 150 includes one or more of copper (Cu), cobalt (Co), tungsten (W), molybdenum (Mo), or ruthenium (Ru).

[0036] Embodiments of the present disclosure are directed to methods of forming transition metal dichalcogenide films. In one or more embodiments, the method of depositing the film includes forming a transition metal oxide film on a substrate surface and subsequently converting the transition metal oxide film into a transition metal dichalcogenide film.

[0037] In some embodiments, a transition metal oxide film is formed directly without forming an intermediate transition metal film layer. The inventors have surprisingly discovered that forming certain metals (e.g., tungsten) on a dielectric layer is more difficult (e.g., longer processing time, elevated temperature) than forming a metal oxide. Additionally, forming a metal layer that is subsequently oxidized requires more processing time and can reduce processing throughput. Therefore, some embodiments of the present disclosure advantageously provide methods for forming a transition metal oxide film without forming an intermediate metal film layer.

[0038] In some embodiments, the substrate surface does not contain a barrier layer. Without being limited by theory, it is believed that forming a metal layer without a barrier layer results in possible diffusion of metal into the underlying material(s). The inventors have surprisingly found that diffusion from metal oxide materials is significantly lower. In some embodiments, the diffusion of metal atoms from metal oxide materials is low enough that the benefit of the barrier layer is negligible. Therefore, eliminating the barrier layer from the process flow is expected to reduce processing time, increase processing throughput, and reduce the resistance of the metal fill because the volume of the fill will be larger.

[0039] In one or more embodiments, the transition metal oxide film is sulfurized using hot Ar / H2S or H2 / H2S gas. In one or more embodiments, the transition metal oxide film is sulfurized using a plasma formed from Ar / H2S or H2 / H2S gas. In one or more embodiments, a transition metal oxide film having tungsten (W) is converted into tungsten disulfide (WS2) by one or more of the sulfurization processes described herein. In some embodiments, a transition metal oxide film having molybdenum (Mo) is converted into molybdenum disulfide (MoS2). In some embodiments, a transition metal oxide film having tantalum (Ta) is converted into tantalum disulfide (TaS2). In some embodiments, a transition metal oxide film having titanium (Ti) is converted into titanium disulfide (TiS2).

[0040] In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film is performed at a plasma power in a range from 25 Watts (W) to 500 Watts (W).

[0041] In one or more embodiments, after forming the transition metal oxide film, the transition metal oxide film is converted into a transition metal dichalcogenide film, the transition metal oxide film having to in the range of to in the range of to in the range of to in the range of to In some embodiments, after forming 1 monolayer, 1 to 5 monolayers, or 1 to 10 monolayers of the transition metal oxide, the transition metal oxide film is converted into a transition metal dichalcogenide film.

[0042] In one or more embodiments, the method further comprises repeatedly forming the transition metal oxide film and converting the transition metal oxide film to form a In one or more embodiments, the transition metal dichalcogenide film has a final thickness of up to Gundam or up to In some embodiments, the transition metal dichalcogenide film has a final thickness of to In some embodiments, the transition metal dichalcogenide film has a final thickness in the range of to in the range of to in the range of to In some embodiments, the transition metal dichalcogenide film has a minimum thickness sufficient to form a continuous film. As used in this manner, a "continuous" film means that less than 5% of the area of ​​the underlying film or layer is exposed through the continuous film.

[0043] In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film is performed at a temperature in a range of about 350° C. to about 500° C. In some embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film is performed at a pressure in a range from 1 Torr to 20 Torr, in a range of 1 Torr to 10 Torr, in a range of 5 Torr to 20 Torr, or in a range of 5 Torr to 10 Torr.

[0044] In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film is performed for a period of time in a range of 30 minutes to 60 minutes. In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide 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.

[0045] refer to Figure 3 One or more embodiments of the present disclosure are directed to a method 200 of forming a transition metal dichalcogenide film. Figure 3 The method depicted in the Figure represents an atomic layer deposition (ALD) process in which a substrate or substrate surface is sequentially exposed to reactive gases in a manner that prevents or minimizes gas phase reactions of the reactive gases. As such, the method avoids chemical vapor deposition (CVD) processes in which the reactive gases mix in the processing chamber to allow gas phase reactions of the reactive gases.

[0046] In one or more embodiments of the present disclosure, method 200 includes optionally pre-treating the substrate at operation 205. A transition metal dichalcogenide film is formed in a deposition process cycle 210. The deposition process cycle 210 can be understood in two stages 220, 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, 234, converts the transition metal oxide film into a transition metal dichalcogenide film.

[0047] In some embodiments, the second stage 230 is performed after the first stage 220 has deposited a transition metal oxide film of a predetermined thickness. 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.

[0048] The first stage 220 includes sequentially exposing the substrate to a transition metal precursor at operation 212 , optionally purging the substrate surface at operation 214 , exposing the substrate to an oxidizing agent at operation 216 , and optionally purging the substrate surface at operation 218 .

[0049] The second stage 230 includes sequentially exposing the substrate to a chalcogenide precursor at operation 232 and optionally purging the substrate surface at operation 234 .

[0050] In some embodiments, method 200 optionally includes a pretreatment operation 205. The pretreatment can be any suitable pretreatment known to a skilled person. Suitable pretreatments include, but are not limited to, preheating, cleaning, soaking, native oxide removal, or deposition of an adhesion layer / barrier layer (e.g., titanium nitride (TiN)). In one or more embodiments, an adhesion layer, such as titanium nitride, is deposited at 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 a plasma gas comprising one or more of: Ar / O2, Ar / H2, or Ar / H2S followed by Ar / H2.

[0051] With respect to the first stage 220 of the deposition process cycle 210, in one or more embodiments, the substrate (or substrate surface) is exposed to a metal precursor to form reactive metal species on the substrate surface at operation 222. The transition metal precursor may be any suitable transition metal-containing compound that can react with the substrate surface (i.e., adsorb onto the substrate surface or chemisorb onto the substrate surface) to leave a transition metal-containing species on the substrate surface.

[0052] 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 include oxygen or halogen atoms. In some embodiments, the metal precursor comprises or consists essentially of one or more of bis(tert-butylimino)bis(dimethylamino)tungsten or bis(tert-butylimino)bis(dimethylamino)molybdenum.

[0053] At operation 224, the processing chamber or substrate surface is purged, as appropriate, to remove unreacted metal precursor, reaction products, and byproducts. As used in this manner, the term "processing chamber" also includes portions of the processing chamber adjacent to the substrate surface and does not encompass the entire interior volume of the processing chamber. For example, in sectors of a spatially separated processing chamber, the transition metal oxide precursor is purged from the portion of the processing chamber adjacent to the substrate surface by any suitable technique, including but not limited to moving the substrate through a gas curtain to a portion or sector of the processing chamber that is free of or substantially free of metal precursor.

[0054] In one or more embodiments, purging the process chamber includes applying a vacuum. In some embodiments, purging the process chamber includes flowing a purge gas over the substrate. In some embodiments, the portion of the process chamber represents a microvolume or a small volume process station within the process chamber. The term "adjacent" in reference to the substrate surface means a physical space close to the substrate surface that can provide sufficient space for surface reactions (e.g., precursor adsorption) to occur. In one or more embodiments, the purge gas is selected from one or more of nitrogen (N2), helium (He), and argon (Ar).

[0055] At 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 oxidation reactant) can be any suitable compound for oxidizing the adsorbed metal precursor to form a transition metal oxide film. In some embodiments, the oxidant includes one or more of H2O, O2, or O3. In some embodiments, the oxidant does not include a plasma. In some embodiments, the transition metal oxide film is stoichiometric. As used in this regard, a "stoichiometric" film has a metal:oxygen ratio within 95% of a generally accepted stoichiometric ratio (e.g., WO3).

[0056] At operation 228, the processing chamber is optionally purged after exposure to the chalcogenide reactant. Purging the processing chamber in operation 228 can be the same process as the purge in operation 224 or a different process. Purging the processing chamber, a portion of the processing chamber, an area adjacent to the substrate surface, etc. removes the oxidant (oxidation reactant), reaction products, and byproducts from the area adjacent to the substrate surface. In one or more embodiments, at operation 228, the processing chamber is optionally purged after exposure to the oxidant.

[0057] At decision 229, the thickness of the transition metal oxide film or the number of cycles of the precursor and the oxidant is considered. If the transition metal oxide film has reached a predetermined thickness or a predetermined number of process cycles have been performed, the method 200 moves to the second stage 230. If the thickness of the transition metal oxide film or the number of process cycles has not reached a predetermined threshold, the method 200 returns to operation 222 to repeat the first stage 220. As described 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 a transition metal dichalcogenide in the second stage 230. In some embodiments, a predetermined number (as few as 1) monolayers of the transition metal oxide film may be formed before being converted to a transition metal dichalcogenide in the second stage 230.

[0058] In the second stage 230, the transition metal oxide film formed in the first stage 220 is converted into a transition metal dichalcogenide film. In some embodiments, converting the transition metal oxide film includes exposing the transition metal oxide film to a chalcogenide precursor at operation 232. The chalcogenide precursor includes one or more of S, Se, or Te. In some embodiments, the chalcogenide precursor includes H2S. In some embodiments, the chalcogenide precursor further includes H2. In some embodiments, the chalcogenide precursor does not include a plasma.

[0059] At operation 234, the processing chamber or substrate surface may be purged. The inventors have discovered that purging the processing chamber at operation 234 is particularly relevant if returning to the first stage 220 to deposit additional transition metal oxide films. Without being limited by theory, it is believed that the purging at operation 234 provides a "clean" substrate surface that enhances adsorption of the metal precursor in operation 222. Additionally, the description of the purging performed at operation 224 or operation 228 also applies to operation 234 in terms of operations and components.

[0060] In one or more embodiments, the deposited film is substantially free of oxygen. As used herein, "substantially free" means that there is less than or equal to about 5% oxygen, 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% oxygen on an atomic basis in the transition metal dichalcogenide film. Thus, without intending to be limited by theory, it is believed that the transition metal dichalcogenide film formed does not generate oxygen as a byproduct, thereby minimizing the possibility of etching / corroding the underlying metal layer.

[0061] At decision 240, the thickness of the transition metal dichalcogenide film or the number of cycles of the deposition process cycle 210 is considered. If the transition metal dichalcogenide film has reached a predetermined thickness or a predetermined number of cycles have been performed, the method 200 moves to optional post-processing operation 250. If the thickness of the transition metal dichalcogenide film or the number of cycles has not reached a predetermined threshold, the method 200 returns to operation 210 to form additional transition metal dichalcogenide films.

[0062] The optional post-processing operation 250 may be, for example, a process to change film properties (eg, annealing) or another film deposition process to grow additional films (eg, additional ALD or CVD processes).

[0063] Method 200 may be performed at any appropriate temperature depending on, for example, the metal precursor, oxidant, chalcogenide reactant, or thermal budget of the device. In one or more embodiments, the use of high temperature processing may be undesirable 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 in the range of about 300° C. to about 500° C.

[0064] 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 the oxidant, and at a second temperature in the range of 400° C. to 450° C. for exposure to the chalcogenide precursor. In some embodiments, the metal and chalcogenide precursors are delivered at the same substrate temperature.

[0065] One or more embodiments of the present disclosure are directed to methods of depositing transition metal dichalcogenide films in high aspect ratio features. High aspect ratio features are trenches, vias, or pillars having a height:width ratio greater than or equal to about 10, 20, or 50 or more. In some embodiments, the transition metal-containing film is conformally deposited on the high aspect ratio feature. As used in this manner, the thickness of the conformal film near the top of the feature is in the range of about 90% to 110% of the thickness at the bottom of the feature.

[0066] Figure 4 Another embodiment of the present disclosure is shown in which a transition metal dichalcogenide (TMDC) liner 240 is formed on the sidewalls of features 120 formed from dielectric material 130. A metal fill 150 is formed in the feature openings between the TMDC liner 240 (formed on the sidewalls of features 120).

[0067] In some embodiments, the TMDC liner 240 is selectively formed on the sidewalls of the feature. In other words, in some embodiments, the TMDC liner 240 is selectively formed on the dielectric material 130 on top of the base material 110. In some embodiments, the TMDC liner 240 is formed on the top surface of the dielectric material 130 and is subsequently removed by any suitable technique known to the skilled artisan (e.g., etching, chemical mechanical planarization). In some embodiments, the TMDC liner 240 is conformally formed in the feature 120 on the base material 110 and the dielectric material 130, and is then subsequently removed from the top of the base material 110 and the dielectric material 130 by a directional etching process, thereby leaving the TMDC liner 240 on the sidewalls of the feature.

[0068] In some embodiments, the TMDC liner reduces the resistivity of the metal gate in the 3D NAND device by replacing the traditional liner and / or barrier material. In some embodiments, the TMDC liner 240 acts as a barrier layer and a liner material. As used in this manner, the barrier layer prevents elements (such as copper, fluorine, etc.) from diffusing or migrating from the metal fill 120 into the underlying dielectric material 130, and the liner material acts as a nucleation layer or nucleation promoter to improve the deposition of the metal fill 120.

[0069] Some embodiments of the present disclosure provide a 3D NAND in which the electron surface scattering between the metal fill 120 and the TMDC liner 240 is less than that between similar metal fills (same material formed by the same process) formed on a titanium nitride (TiN) liner.

[0070] In some embodiments, the TMDC liner includes tungsten disulfide (WS2). In some embodiments, the TMDC liner 240 consists essentially of tungsten disulfide (WS2). As used in this manner, the term "consisting essentially of" means that the sum of tungsten and sulfur atoms accounts for greater than or equal to 95%, 98%, 99%, or 99.5% of the TMDC liner 240.

[0071] In some embodiments, for less than With a thickness of , the TMDC liner 240 has a resistivity less than or equal to 12 μΩ-cm.

[0072] According to one or more embodiments, before and / or after forming the layer, the substrate undergoes processing. 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 the 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 chamber. Thus, the processing device can include multiple chambers in communication with a transfer station. Such a device can be referred to as a "cluster tool" or a "cluster system", and the like.

[0073] In general, a cluster tool is a modular system that includes multiple chambers that perform various functions, including substrate centering and orientation, degassing, annealing, deposition, and / or etching. According to one or more embodiments, a cluster tool includes at least a first chamber and a central transfer chamber. The central transfer chamber can accommodate a robot that can shuttle substrates between and among processing chambers and load lock chambers. The transfer chamber is typically maintained under vacuum conditions and provides an intermediate platform for shuttling substrates from one chamber to another and / or to a load lock chamber positioned at the front end of the cluster tool. Two well-known cluster tools that may be suitable for use in the present disclosure are: and All are available from Applied Materials, Inc., Santa Clara, California. However, the exact arrangement and combination of chambers may be varied for the purpose of performing specific steps of the processes as described herein. Other processing chambers that may be used include, but are not limited to, cyclical layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, chemical cleaning, thermal treatment (such as RTP), plasma nitridation, degassing, orientation, hydroxylation, and other substrate processes. By performing the processes in chambers on a cluster tool, surface contamination of the substrate caused by atmospheric impurities may be avoided without oxidation prior to deposition of subsequent films.

[0074] According to one or more embodiments, the substrate is continuously under vacuum or "load lock" conditions and is not exposed to ambient air when moving from one chamber to the next. The transfer chamber is thus under vacuum and is "evacuated" at 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, a 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.

[0075] Substrates may be processed in a single substrate deposition chamber, where a single substrate is loaded, processed, and unloaded before another substrate is processed. Substrates may also be processed in a continuous manner (similar to a conveyor belt system), where multiple substrates are individually loaded into a first portion of the chamber, moved through the chamber, and unloaded from a second portion of the chamber. The shape of the chamber and associated conveyor belt system may form a straight path or a curved path. Additionally, the processing chamber may be a turntable, where multiple substrates move about a central axis and are exposed to deposition, etching, annealing, cleaning, etc. processes throughout the turntable path.

[0076] During processing, the substrate may be heated or cooled. Such heating or cooling may be achieved by any suitable means, including but not limited to changing the temperature of the substrate support and flowing heated or cooled gas to the substrate surface. In some embodiments, the substrate support includes a heater / cooler that can be controlled to change the substrate temperature in a conductive manner. In one or more embodiments, the gas (reactive gas or inert gas) used is heated or cooled to locally change the substrate temperature. In some embodiments, the heater / cooler is positioned within the chamber, adjacent to the substrate surface, to change the substrate temperature in a convective manner.

[0077] The substrate may also be stationary or rotated during processing. A rotating substrate may be rotated continuously or in discrete steps (about the substrate axis). For example, the substrate may be rotated throughout the entire process, or the substrate may be rotated a small amount between exposures to different reactive or purge gases. Rotating the substrate during processing (continuously or in steps) may help produce a more uniform deposition or etch by minimizing the effects of local variability, such as gas flow geometry.

[0078] For ease of description, spatially relative terms such as "below," "below," "lower," "above," "upper," and similar terms may be used herein to describe the relationship of one element or feature to another (other) element or feature as depicted in the figures. It should be understood that these spatially relative terms are intended to encompass different orientations of the elements in use or operation in addition to the orientation depicted in the figures. For example, if the elements in the figures are flipped, elements described as "below" or "below" other elements or features will be oriented "above" the other elements or features. Thus, the exemplary term "below" may encompass orientations above as well as below. Elements may be otherwise oriented (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly.

[0079] In the context of describing the materials and methods discussed herein, (especially in the context of the following claims), the use of the terms "a" and "an" and "the" and similar representatives should be interpreted as covering the singular and the plural, unless otherwise specified herein or clearly contradicted by the context. Unless otherwise indicated herein, the enumeration of value ranges herein is intended only to be used as a shorthand method for representing each individual value within the range individually, and each individual value is incorporated into this specification as if it were individually enumerated herein. Unless otherwise indicated herein or clearly contradicted by the context, all methods described herein can be performed in any appropriate order. Unless otherwise stated, the use of any and all examples or illustrative language (e.g., "such as") provided herein is intended only to better illustrate the materials and methods, and is not intended to limit the scope. The language in the specification should not be interpreted as indicating that any undeclared element is essential to the practice of the disclosed materials and methods.

[0080] References throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment" mean that a particular feature, structure, material, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present disclosure. Thus, phrases such as "in one or more embodiments," "certain embodiments," "in an embodiment," or "in an embodiment" appearing in various places throughout this specification are not necessarily representative of the same embodiment of the present disclosure. Additionally, particular features, structures, materials, or characteristics may be combined in any appropriate manner in one or more embodiments.

[0081] Although the disclosure herein has been described with reference to specific embodiments, it will be understood by those skilled in the art that the described embodiments are merely illustrative of the principles and applications of the disclosure. It will be apparent to those skilled in the art that various modifications and variations may be made to the methods and apparatus of the disclosure without departing from the spirit and scope of the disclosure. Therefore, the disclosure may include modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A method for reducing the resistivity of a metal gate in a 3D NAND device, the method comprising: forming a transition metal dichalcogenide (TMDC) liner on the dielectric material; as well as A metal filler is deposited on the TMDC liner.

2. The method of claim 1, wherein the TMDC liner acts as a barrier layer and a liner.

3. The method of claim 1, wherein the electron surface scattering between the metal filler and the TMDC liner is less than the electron surface scattering between the same metal fillers formed on a titanium nitride (TiN) liner.

4. The method of claim 1, wherein the TMDC liner has to The thickness is in the range of 5. The method of claim 1, wherein the TMDC liner acts as a fluorine diffusion barrier.

6. The method of claim 1, wherein the TMDC liner comprises tungsten disulfide (WS2).

7. The method of claim 1, wherein the step of forming the TMDC liner comprises: The dielectric material is exposed to a chalcogenide precursor including one or more of sulfur (S), selenium (Se), or tellurium (Te).

8. The method of claim 7, wherein the transition metal dichalcogenide film is substantially free of oxygen.

9. The method of claim 1, wherein the dielectric material forms sidewalls of features formed on a substrate and the TMDC liner is substantially conformal over the features.

10. The method of claim 1, wherein the TMDC liner comprises one or more of molybdenum (Mo), tungsten (W), tantalum (Ta), or titanium (Ti).

11. The method of claim 1, wherein for less than The TMDC liner has a thickness of less than or equal to 12 μΩ-cm.

12. A 3D NAND device, comprising: a substrate having features including a base material and at least one sidewall, the base including a channel material, the at least one sidewall including a dielectric material; a transition metal dichalcogenide (TMDC) liner formed on the at least one sidewall, leaving a feature opening; as well as A metal filler is formed in the feature opening.

13. The element of claim 12, wherein the TMDC liner acts as a barrier layer and a liner.

14. The element of claim 12, wherein the TMDC liner has to The thickness is in the range of 15. The element of claim 12, wherein the TMDC liner acts as a fluorine diffusion barrier.

16. The element of claim 12, wherein the TMDC liner comprises tungsten disulfide (WS2).

17. The element of claim 12, wherein the transition metal dichalcogenide film is substantially free of oxygen.

18. The element of claim 12, wherein the TMDC liner comprises one or more of molybdenum (Mo), tungsten (W), tantalum (Ta), or titanium (Ti).

19. A method of forming a transition metal dichalcogenide film on a substrate surface comprising at least one feature, the method comprising: exposing the substrate surface to a metal precursor and an oxidant sequentially to directly deposit a transition metal oxide film, the metal precursor comprising bis(tert-butylimino)bis(dimethylamino)tungsten or bis(tert-butylimino)bis(dimethylamino)molybdenum, the transition metal oxide film being substantially 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 dichalcogenide film, wherein the chalcogenide precursor includes H2S, and the transition metal dichalcogenide film has to The thickness in the range of Wherein the substrate surface is maintained at a temperature in the range of about 350°C to about 450°C.

Images