Conformal Metal Dichalcogenides

Abstract

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

Description

[Technical field]

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

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

[0003] Chemical vapor deposition (CVD) is one of the most common deposition processes employed to deposit layers on substrates. CVD is a flux-dependent deposition technique that requires precise control of the substrate temperature and the precursors introduced to the processing chamber to produce a desired layer of uniform thickness. These requirements become more critical as substrate sizes increase, creating the need for more complex chamber designs and gas flow techniques to maintain sufficient uniformity.

[0004] A variant of CVD that exhibits excellent step coverage is cyclic deposition or atomic layer deposition (ALD). Cyclic deposition is based on atomic layer epitaxy (ALE) and employs chemisorption techniques to deliver precursor molecules onto a substrate surface in successive cycles. The cycles expose 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 cycles are repeated to form a layer of a desired thickness.

[0005] The increasing complexity of advanced microelectronic devices places stringent demands on currently used deposition techniques. Unfortunately, there are a limited number of viable chemical precursors available that have the requisite 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 promising candidates to mitigate the metal migration issues associated with film interconnect downscaling. Moreover, TMDCs have better electrical conductivity and carrier mobility compared to current processes in 3D NAND devices. Recent TMDC methods require high temperature processes that may not be compatible with the thermal budget of the devices.

[0007] There is therefore a need for conformal TMDCs that can be grown by low-temperature thermal processes 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 of forming a transition metal dichalcogenide film, the method including depositing a transition metal oxide film on a substrate surface and converting the transition metal oxide film to 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 comprising at least one feature. The method includes sequentially exposing the substrate surface to a metal precursor and an oxidizing agent to directly deposit a transition metal oxide film. The metal precursor includes bis(t-butylimino)bis(dimethylamino)tungsten or bis(t-butylimino)bis(dimethylamino)molybdenum. The transition metal oxide film is substantially conformal across the at least one feature. The transition metal oxide film is exposed to a chalcogenide precursor to convert the transition metal oxide film to a transition metal dichalcogenide film. The chalcogenide precursor is H 2 The transition metal dichalcogenide film includes S and 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.

[0010] So that the above-recited features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above may be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that since the present disclosure may admit of other equally effective embodiments, the accompanying drawings only illustrate typical embodiments of the present disclosure and therefore should not be considered as limiting its scope. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a substrate according to one or more embodiments of the present disclosure. [Diagram 2] 1 is a cross-sectional view of a substrate according to one or more embodiments of the present disclosure. [Diagram 3] FIG. 1 is a process flow diagram of a method according to one or more embodiments of the present disclosure. [Figure 4] 1 is a cross-sectional view of a substrate according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Before describing certain example embodiments of the present disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description as the disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0013] The term "substrate" as used herein and in the appended claims refers to a surface or portion of a surface on which a process acts. Those skilled in the art will appreciate that a reference to a substrate may also refer to only a portion of the substrate, unless the context clearly indicates otherwise. Furthermore, a reference to deposition on a substrate can refer to both a bare substrate and a substrate having one or more films or features deposited or formed thereon.

[0014] As used herein, the term "substantially free of oxygen" means that there is less than or equal to about 5% oxygen in the transition metal dichalcogenide film, 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%.

[0015] 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, as well as any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, but are not limited to, semiconductor wafers. Substrates may be exposed to pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure, and / or bake the substrate surface. In addition to directly processing films on the surface of the substrate itself, in this disclosure, any of the disclosed film processing steps may also be performed on an underlayer formed on the substrate as disclosed in more detail below, and the term "substrate surface" is intended to include such underlayers as the context indicates. Thus, for example, when a film / layer or partial film / layer is deposited on the substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0016] "Substrate surface" as used herein refers to any substrate surface upon which a layer may be formed. A substrate surface may have one or more features formed therein, one or more layers formed thereon, and combinations thereof. The substrate (or substrate surface) may be pretreated prior to the disclosed methods, for example, by polishing, etching, reducing, oxidizing, halogenating, hydroxylating, annealing, baking, and the like.

[0017] The substrate may be any substrate capable of having materials deposited thereon, such as a silicon substrate, a III-V compound substrate, a silicon germanium (SiGe) substrate, an epi substrate, a silicon-on-insulator (SOI) substrate, a display substrate such as a liquid crystal display (LCD), a plasma display, an electroluminescent (EL) lamp display, a solar array, a solar panel, a light emitting diode (LED) substrate, a semiconductor wafer, etc. In some embodiments, one or more additional layers may be disposed on the substrate, and thus the 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, etc., or a combination thereof may be disposed on the substrate, and may have a transition metal dichalcogenide layer formed on such one or more layers.

[0018] According to one or more embodiments, the term "on" with respect to a film or layer of a film includes that the film or layer is directly on a surface, e.g., a substrate surface, as well as that there are one or more underlayers between the film or layer and the surface, e.g., the substrate surface. Thus, in one or more embodiments, the phrase "on the substrate surface" is intended to include one or more underlayers. In other embodiments, the phrase "directly on" refers to a layer or film that contacts a surface, e.g., the substrate surface, without an intervening layer. Thus, the phrase "a layer directly on the substrate surface" refers to a layer that directly contacts the substrate surface, without an intervening layer.

[0019] According to one or more embodiments, the disclosed method utilizes an atomic layer deposition (ALD) process. In such embodiments, the substrate surface is exposed to precursors (or reactive gases) sequentially. Throughout this specification, "sequentially" as used herein means that the duration of precursor exposure does not intentionally overlap with exposure to co-reagents in a manner intended to produce a gas-phase reaction. Some overlap may occur, but it is understood that this overlap is unintentional.

[0020] As used herein and in the appended claims, the terms "precursor," "reactant," "reactive gas," and the like are used interchangeably to refer to any gas species capable of reacting with the substrate surface.

[0021] 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 herein and in the appended claims, the terms "reactive compound," "reactive gas," "reactive species," "precursor," "process gas," and the like are used interchangeably to mean a substance having a species capable of reacting with a substrate surface or a material on the substrate surface in a surface reaction (e.g., chemisorption, oxidation, reduction). A substrate or a portion of a substrate is sequentially exposed to two or more reactive compounds that are introduced into a reaction zone of a processing chamber. In a time-domain ALD process, exposure to each reactive compound is separated by a time delay to allow each compound to deposit and / or react on the substrate surface. In a spatial ALD process, different portions of the substrate surface, or different portions of materials on the substrate surface, are exposed to two or more reactive compounds simultaneously, such that any given point on the substrate is substantially exposed to only one reactive compound at a time. As used herein and in the appended claims, the term "substantially" as used in this regard means that it is possible that small portions of a substrate may be exposed to multiple reactive gases simultaneously due to diffusion, and that such simultaneous exposure is unintended, as will be understood by those of skill in the art.

[0022] In one embodiment of a time-domain ALD process, a first reactive gas (i.e., a first precursor or compound A) is pulsed into the reaction zone, followed by a first time delay. Then, a second precursor or compound B is pulsed into the reaction zone, followed by a second delay. During each time delay, a purge gas, such as argon, is introduced into the process chamber to purge the reaction zone or otherwise remove residual reactive compounds or by-products from the reaction zone. Alternatively, the purge gas can flow continuously throughout the deposition process, such that only the purge gas flows during the time delay between pulses of reactive compounds. The reactive compounds are alternatively pulsed until a desired film or film thickness is formed on the substrate surface.

[0023] In some embodiments, an ALD process that pulses compound A, purge gas, compound B, and purge gas is cyclic. The cycle can start with either compound A or compound B, and continue in each order of the cycle until a film with a desired thickness is achieved. In some embodiments, there can be two reactants, A and B, that are alternately pulsed and purged.

[0024] 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 is utilized during each deposition cycle (e.g., ABC). In some embodiments, a series of alternating exposures to compound A and compound B may be performed before exposure to compound C (e.g., ABABC).

[0025] In spatial ALD processes, a first and a second reactive gas are simultaneously supplied to a reaction zone but separated by an inert gas and / or vacuum curtain. The substrate is moved relative to the gas supply so that any given point on the substrate is exposed to both the first and the second reactive gases.

[0026] The embodiments of the present disclosure provide a method for forming a transition metal dichalcogenide film for use as a channel material, liner or barrier layer in 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 a subsequently deposited metal, adhesively bond the metal to the underlying dielectric material, and block diffusion of the metal element into the underlying dielectric material.

[0027] In one or more embodiments, the transition metal dichalcogenide film serves 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.

[0028] Embodiments of the present disclosure provide a low thermal budget approach to achieving high quality 2D transition metal dichalcogenide films for temperature sensitive device architectures.

[0029] Referring to FIG. 1, a substrate 100 is shown that includes a base material 110 having at least one feature 120 formed from a material 130. The surfaces of the base material 110 and the material 130 form the 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 figure shows a substrate with three features for purposes of explanation, but one of ordinary skill 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.

[0030] The shape of the features 120 can be any suitable shape, including, but not limited to, trenches and cylindrical vias. The term "feature" as used in this context means any intentional surface irregularity. Suitable examples of features include, but are not limited to, trenches having two sidewalls and a bottom, peaks having a top and two sidewalls, and vias having a bottom and a cylindrical or elliptical cylindrical sidewall. The features can 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, 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.

[0031] 2, each of the at least one features 120 has a transition metal dichalcogenide film 140 deposited thereon. In one or more embodiments, the substrate 100 includes a metal filling 150 deposited on the transition metal dichalcogenide film 140 in each of the at least one features 120. In one or more embodiments, the metal filling 150 comprises a high conductivity metal. In some embodiments, the metal filling 150 includes one or more of copper (Cu), cobalt (Co), tungsten (W), molybdenum (Mo), or ruthenium (Ru).

[0032] Embodiments of the present disclosure are directed to a method of forming a transition metal dichalcogenide film. In one or more embodiments, a method of depositing a film includes forming a transition metal oxide film on a substrate surface and then converting the transition metal oxide film to a transition metal dichalcogenide film.

[0033] In some embodiments, the transition metal oxide film is directly formed without forming a transition metal film intermediate. The inventors have surprisingly discovered that forming some metals (e.g., tungsten) on a dielectric layer is more difficult (e.g., longer processing time, higher temperature) than forming a metal oxide. Furthermore, forming a metal layer that is subsequently oxidized requires more processing time and reduces processing throughput. Thus, some embodiments of the present disclosure advantageously provide a method of forming a transition metal oxide film without forming a metal film intermediate.

[0034] In some embodiments, the substrate surface does not include a barrier layer. Without being bound by theory, it is believed that the formation of a metal layer without a barrier leads to possible diffusion of the metal into the underlying material(s). The inventors have surprisingly discovered that diffusion from metal oxide materials is significantly lower. In some embodiments, the diffusion of metal atoms from metal oxide materials is sufficiently low that the benefit of the barrier layer is negligible. Thus, the elimination of the barrier layer from the process flow is expected to reduce processing time, increase throughput, and reduce the resistance of the metal fill, since the volume of the metal fill will be larger.

[0035] In one or more embodiments, the transition metal oxide film is formed by annealing in high temperature Ar / H 2 S or H 2 / H 2 In one or more embodiments, the transition metal oxide film is sulfurized using Ar / H 2 S or H 2 / H 2 In one or more embodiments, the tungsten (W)-bearing transition metal oxide film is sulfurized using a plasma formed from S gas. In one or more embodiments, the tungsten (W)-bearing transition metal oxide film is converted to tungsten disulfide (WS) by one or more of the sulfurization processes described herein. 2 In some embodiments, the molybdenum (Mo)-bearing transition metal oxide film is converted to molybdenum disulfide (MoS 2In some embodiments, the tantalum (Ta)-containing transition metal oxide film is converted to tantalum disulfide (TaS 2 In some embodiments, the titanium (Ti)-containing transition metal oxide film is converted to titanium sulfide (TiS 2 )

[0036] In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film occurs at a plasma power in the range of 25 watts (W) to 500 watts (W).

[0037] In one or more embodiments, the transition metal oxide film is converted to a transition metal dichalcogenide film after forming a transition metal oxide film having a thickness in the range of 5 Å to 50 Å, or in the range of 10 Å to 20 Å, or in the range of 10 Å to 35 Å, or in the range of 10 Å to 25 Å, or in the range of 15 Å to 30 Å. In some embodiments, the transition metal oxide film is converted to a transition metal dichalcogenide film after forming 1 monolayer, 1 to 5 monolayers, or 1 to 10 monolayers of the transition metal oxide.

[0038] In one or more embodiments, the method further includes repeating the steps of forming the transition metal oxide film and converting the transition metal oxide film to form a transition metal dichalcogenide film with a final thickness of up to 200 Å. In one or more embodiments, the transition metal dichalcogenide 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 dichalcogenide film has a final thickness in the range of 20 Å to 30 Å. In some embodiments, the transition metal dichalcogenide film has a final thickness in the range of 5 Å to 50 Å, or in the range of 8 Å to 25 Å, or in the range of 10 Å to 20 Å. 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.

[0039] In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film occurs at a temperature in the range of about 350° C. to about 500° C. In some embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film occurs at a pressure in the range of 1 to 20 Torr, in the range of 1 Torr to 20 Torr, in the range of 5 Torr to 20 Torr, or in the range of 5 Torr to 10 Torr.

[0040] In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film is performed for a time ranging from 30 minutes to 60 minutes. In one or more embodiments, converting the transition metal oxide film to a transition metal dichalcogenide film includes exposing the transition metal oxide film to a chalcogenide precursor including one or more of sulfur (S), selenium (Se), or tellurium (Te). In some embodiments, the chalcogenide precursor is H 2 Contains S.

[0041] With reference to Figure 3, one or more embodiments of the present disclosure are directed to a method 200 of forming a transition metal dichalcogenide film. The method illustrated in Figure 3 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 reaction of the reactive gases. In so doing, the method avoids chemical vapor deposition (CVD) processes in which reactive gases are mixed in a processing chamber to enable gas phase reaction of the reactive gases.

[0042] In one or more embodiments of the present disclosure, the method 200 optionally includes pretreating the substrate at step 205. A transition metal dichalcogenide film is formed in a deposition process cycle 210. The deposition process cycle 210 can be understood in two phases 220, 230. A first phase 220, including steps 222, 224, 226, and 228, forms a transition metal oxide film on the substrate surface. A second phase 230, including steps 232, 234, converts the transition metal oxide film to a transition metal dichalcogenide film.

[0043] In some embodiments, the second phase 230 is performed after the first phase 220 has deposited a predetermined thickness of the transition metal oxide film. In some embodiments, the second phase 230 is performed after a single step of the first phase 220. In some embodiments, the second phase 230 is performed after multiple cycles of the first phase 220.

[0044] The first phase 220 includes sequential exposure of the substrate to a transition metal precursor in step 222, optional purging of the substrate surface in step 224, exposure of the substrate to an oxidizing agent in step 226, and optional purging of the substrate surface in step 228.

[0045] The second phase 230 involves the continued exposure of the substrate to a chalcogenide precursor in step 232 and an optional purging of the substrate surface in step 234 .

[0046] In some embodiments, the method 200 includes an optional pretreatment step 205. The pretreatment can be any suitable pretreatment known to one of skill in the art. Suitable pretreatments include, but are not limited to, preheating, cleaning, soaking, native oxide removal, or deposition of an adhesion / barrier layer (e.g., titanium nitride (TiN)). In one or more embodiments, an adhesion layer such as titanium nitride is deposited in step 205. In some embodiments, the substrate surface does not include a barrier layer, as described above. In one or more embodiments, the optional pretreatment step 205 includes a pretreatment step using a fluorine-based fluoride (HF) ion exchanger such as Ar / O2 , Ar / H 2 , or Ar / H 2 S followed by Ar / H 2 , comprising flowing a plasma gas including one or more of:

[0047] With respect to the first phase 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 in step 222. The transition metal precursor can be any suitable transition metal-containing compound capable of reacting with (i.e., adsorbing or chemisorbing onto) the substrate surface to leave a transition metal-containing species on the substrate surface.

[0048] 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 comprise oxygen or halogen atoms. In some embodiments, the metal precursor comprises or consists essentially of one or more of bis(t-butylimino)bis(dimethylamino)tungsten or bis(t-butylimino)bis(dimethylamino)molybdenum.

[0049] In step 224, the process chamber or substrate surface is optionally purged to remove unreacted metal precursor, reaction products and by-products. The term "process chamber" as used in this manner includes the portion of the process chamber adjacent to the substrate surface without encompassing the complete internal volume of the process chamber. For example, in a spatially separated sector of the process chamber, the portion of the process chamber adjacent to the substrate surface is purged of transition metal oxide precursor by any suitable technique, including but not limited to, moving the substrate through a gas curtain to a portion or sector of the process chamber that does not contain or is substantially free of metal precursor.

[0050] In one or more embodiments, purging the processing chamber includes applying a vacuum. In some embodiments, purging the processing chamber includes flowing a purge gas across the substrate. In some embodiments, the portion of the processing chamber refers to a micro-volume or small-volume process station within the processing chamber. The term "adjacent" referring to the substrate surface means the physical space next to the surface of the substrate that can provide sufficient space for surface reactions (e.g., precursor adsorption) to occur. In one or more embodiments, the purge gas is nitrogen (N 2 ), helium (He), and argon (Ar).

[0051] In step 226, the substrate (or substrate surface) is exposed to an oxidizing agent to form a transition metal oxide film on the substrate. The oxidizing agent (also called an oxide reactant) can be any suitable compound for oxidizing the absorbed metal precursor to form the transition metal oxide film. In some embodiments, the oxidizing agent is H 2 O, O 2 Or O 3 In some embodiments, the oxidizing agent does not include a plasma. In some embodiments, the transition metal oxide film is stoichiometric. As used in this context, a "stoichiometric" film has a metal:oxygen ratio within 95% of the commonly accepted stoichiometric ratio (e.g., WO 3 ).

[0052] In step 228, the processing chamber is optionally purged after exposure to the chalcogenide reactant. Purging the processing chamber in step 228 can be the same process as purging in step 224 or a different process. Purging the processing chamber, portions of the processing chamber, areas adjacent to the substrate surface, etc. removes oxidizing agents (oxide reactants), reaction products, and by-products from the areas adjacent to the substrate surface. In one or more embodiments, in step 228, the processing chamber is optionally purged after exposure to the oxidizing agent.

[0053] At decision 229, the thickness of the transition metal oxide film or the number of precursor and oxidant cycles is considered. If the transition metal oxide film reaches a predetermined thickness or a predetermined number of process cycles, the method 200 moves to a second phase 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 step 222 to repeat the first phase 220. As identified above, in some embodiments, the transition metal oxide film may be formed to a predetermined thickness in the first phase 220 before being converted to a transition metal dichalcogenide in the second phase 230. In some embodiments, a predetermined number of monolayers (as little as one) of the transition metal oxide film may be formed before being converted to a transition metal dichalcogenide in the second phase 230.

[0054] In a second phase 230, the transition metal oxide film formed in the first phase 220 is converted to 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 in step 232. The chalcogenide precursor includes one or more of S, Se, or Te. In some embodiments, the chalcogenide precursor includes H 2 In some embodiments, the chalcogenide precursor comprises H 2 In some embodiments, the chalcogenide precursor is plasma-free.

[0055] In step 234, the process chamber or substrate surface may be purged. The inventors have discovered that purging the process chamber in step 234 is particularly important when returning to the first phase 220 to deposit an additional transition metal oxide film. Without being bound by theory, it is believed that the purging in step 234 provides a "clean" substrate surface that improves the adsorption of the metal precursor in step 222. In some cases, the descriptions of the purging performed in step 224 or step 228, both in steps and compositions, also apply to step 234.

[0056] 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 in the transition metal dichalcogenide film, 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%, on an atomic basis. Thus, without intending to be bound by theory, it is believed that the transition metal dichalcogenide film is formed without producing oxygen as a by-product, thus minimizing the possibility of etching / corroding the underlying metal layer.

[0057] At decision 240, the thickness of the transition metal dichalcogenide film or the number of cycles of the deposition process cycle 210 is determined. If the transition metal dichalcogenide film has reached a predetermined thickness or a predetermined number of process cycles have been performed, the method 200 moves to an optional post-treatment step 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 step 210 to form additional transition metal dichalcogenide films.

[0058] The optional post-treatment step 250 can be, for example, a process to modify the film properties (eg, annealing) or a further film deposition process to grow an additional film (eg, an additional ALD or CVD process).

[0059] The method 200 may be performed at any suitable temperature, depending, for example, on the metal precursor, oxidant, chalcogenide reactant, or thermal history 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.

[0060] In some embodiments, exposure to the transition metal precursor or metal precursor (step 212) occurs at a different temperature than exposure to the oxidizer (step 226) or exposure to the chalcogenide precursor (step 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 oxidizer, 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 provided at the same substrate temperature.

[0061] One or more embodiments of the present disclosure are directed to methods of depositing transition metal dichalcogenide films in high aspect ratio features. The high aspect ratio features are trenches, vias, or pillars having height:width ratios greater than or equal to about 10, 20, or 50. In some embodiments, the transition metal-containing film is conformally deposited on the high aspect ratio feature. The conformal film used in this manner has a thickness near the top of the feature that is within about 90-110% of the thickness at the bottom of the feature.

[0062] 4 illustrates another embodiment of the present disclosure in which transition metal dichalcogenide (TMDC) liners 240 are formed on the sidewalls of features 120 formed from dielectric material 130. Metal fills 150 are formed in the feature openings between the TMDC liners 240 formed on the sidewalls of features 120.

[0063] In some embodiments, the TMDC liner 240 is selectively formed on the sidewalls of the feature. Stated differently, in some embodiments, the TMDC liner 240 is selectively formed on the dielectric material 130 over the base material 110. In some embodiments, the TMDC liner 240 is formed on the top surface of the dielectric material 130 and then removed by any suitable technique known to those of skill in the art (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 then subsequently removed from the base material 110 and the top of the dielectric material 130 by a directional etching process, leaving the TMDC liner 240 on the sidewalls of the feature.

[0064] In some embodiments, the TMDC liner reduces the resistance of metal gates in 3D NAND devices by replacing traditional liner and / or barrier materials. In some embodiments, the TMDC liner 240 acts as a barrier layer and a liner material. The barrier layer used in this manner prevents diffusion or migration of elements (such as copper, fluorine, etc.) 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.

[0065] Some embodiments of the present disclosure provide less surface scattering of electrons between the metal filling 120 and the TMDC liner 240 than between a similar metal filling (same material formed by the same process) formed on a titanium nitride (TiN) liner.

[0066] In some embodiments, the TMDC liner is made of tungsten disulfide (WS 2 In some embodiments, the TMDC liner 240 comprises essentially tungsten disulfide (WS 2 As used in this manner, the term "consists essentially of" means that TMDC liner 240 is greater than or equal to 95%, 98%, 99%, or 99.5% of the sum of tungsten atoms and sulfur atoms.

[0067] In some embodiments, the TMDC liner 240 has a resistivity less than or equal to 12 μΩcm for a thickness less than 35 Å.

[0068] According to one or more embodiments, the substrate undergoes processing prior to and / or after forming the layer. The processing can be performed in the same chamber or in one or more separate processing chambers. In some embodiments, the substrate is transferred from the first chamber to a separate second chamber for further processing. The substrate can be transferred directly from the first chamber to the separate processing chamber, or the substrate can be transferred from the first chamber to one or more transfer chambers and then to the separate processing chamber. Thus, the processing apparatus can include multiple chambers in communication with a transfer station. This type of apparatus can be referred to as a "cluster tool" or a "clustered system", etc.

[0069] Generally, a cluster tool is a modular system with multiple chambers that perform various functions, including substrate center-finding and orientation, degassing, annealing, deposition, and / or etching. According to one or more embodiments, the cluster tool includes at least a first chamber and a central transfer chamber. The central transfer chamber may house a robot that can shuttle substrates between processing chambers and load lock chambers. The transfer chamber is generally maintained in vacuum conditions and provides an intermediate stage for shuttling substrates from one chamber to another and / or to a load lock chamber located at the front end of the cluster tool. Two well-known cluster tools that may be adapted for the present disclosure are the Centura® and Endura®, both available from Applied Materials, Inc. of Santa Clara, Calif. However, the exact arrangement and combination of chambers may be varied for the purpose of performing the specific steps of the processes described herein. Other processing chambers that may be used include, but are not limited to, cyclic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, chemical cleaning, thermal treatments such as RTP, plasma nitridation, degassing, alignment, hydroxylation, and other substrate processes. By performing processes in chambers on a cluster tool, surface contamination of the substrate by atmospheric impurities can be avoided without oxidation prior to depositing a subsequent film.

[0070] According to one or more embodiments, the substrate is continuously under vacuum or "load-lock" conditions and is not exposed to ambient air when being transferred from one chamber to the next. The transfer chamber is therefore under vacuum and is "pumped down" under vacuum pressure. An inert gas may be present in the processing chamber or the transfer chamber. In some embodiments, an inert gas is used as a purge gas to remove some or all of the reactants (e.g., a reactant). According to one or more embodiments, a purge gas is injected at the outlet of the deposition chamber to prevent the transfer of reactants (e.g., a reactant) 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.

[0071] Substrates may be processed in single-substrate deposition chambers, where a single substrate is loaded, processed, and unloaded before another substrate is processed. Substrates may also be processed continuously, as with a conveyor 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 geometry of the chamber and associated conveyor system may form a linear or curved path. Additionally, the processing chamber may be a carousel, where multiple substrates are moved about a central axis and exposed to processes such as deposition, etching, annealing, cleaning, etc. throughout the carousel path.

[0072] During processing, the substrate may be heated or cooled. Such heating or cooling may be accomplished by any suitable means, including, but not limited to, altering the temperature of the substrate support and flowing a heated or cooled gas over the substrate surface. In some embodiments, the substrate support includes a heater / cooler that may be controlled to conductively alter the substrate temperature. In one or more embodiments, the gas employed (either reactive or inert gas) is heated or cooled to locally alter the substrate temperature. In some embodiments, the heater / cooler is positioned in the chamber adjacent to the substrate surface to convectively alter the substrate temperature.

[0073] The substrate may also be stationary or rotated during processing. A rotating substrate may be rotated (about the substrate axis) continuously or in discrete steps. For example, the substrate may be rotated throughout the entire process, or the substrate may be rotated only 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, for example, by minimizing the effects of local variability in gas flow geometry.

[0074] Spatially relative terms such as "beneath," "below," "lower," "above," "upper," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to another element or feature(s). It will be understood that the spatially relative terms are intended to encompass different orientations of the device during use or processing in addition to the orientation shown in the figures. For example, if a device in the figures were turned over, elements described as being "below" or "below" other elements or features would be oriented "above" those other elements or features. Thus, the exemplary term "below" may encompass both an upward and downward orientation. A device may be oriented differently (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.

[0075] In the context of describing the materials and methods described herein (particularly in the context of the claims below), the use of the terms "a" and "an" and "the" and similar referents should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein may be performed in any suitable order, unless otherwise indicated herein or otherwise clearly contradicted by the context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended merely to better describe the materials and methods, and does not impose limitations on the scope unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.

[0076] 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 with respect to that embodiment is included in at least one embodiment of the present disclosure. Thus, the appearance of phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment of the present disclosure. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0077] Although the disclosure of this specification has been described with reference to specific embodiments, those skilled in the art will understand that the described embodiments merely illustrate the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed method and apparatus without departing from the spirit and scope of the present disclosure. Thus, the present disclosure can include modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. 1. A method for reducing resistance of a metal gate in a 3D NAND device, the method comprising: forming a transition metal dichalcogenide (TMDC) liner on a dielectric material; depositing a metal fill on the TMDC liner; A method comprising:

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

3. 10. The method of claim 1, wherein surface scattering of electrons between the metal fill and the TMDC liner is less than surface scattering of electrons between a similar metal fill formed on a titanium nitride (TiN) liner.

4. The method of claim 1 , wherein the TMDC liner has a thickness in the range of 10 Å to 20 Å.

5. The method of claim 1 , wherein the TMDC liner acts as a fluorine diffusion barrier.

6. The TMDC liner is made of tungsten disulfide (WS ２ 2. The method of claim 1 , comprising:

7. 10. The method of claim 1, wherein forming the TMDC liner comprises exposing the dielectric material to a chalcogenide precursor comprising 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 a sidewall of a feature formed on a substrate, and the TMDC liner is substantially conformal across the feature.

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. 10. The method of claim 1, wherein the TMDC liner has a resistivity less than or equal to 12 μΩ cm for a thickness less than 35 Å.

12. a substrate having a feature including a base material and at least one sidewall, the bottom including a channel material and 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; a metal fill formed in the feature opening; 3. A 3D NAND device comprising:

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

14. The device of claim 12, wherein the TMDC liner has a thickness in the range of 10 Å to 20 Å.

15. The device of claim 12 , wherein the TMDC liner acts as a fluorine diffusion barrier.

16. The TMDC liner is made of tungsten disulfide (WS ２ 13. The device of claim 12, comprising:

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

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

19. 1. A method for forming a transition metal dichalcogenide film on a substrate surface having at least one feature, the method comprising: sequentially exposing the substrate surface to a metal precursor and an oxidant 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, and the transition metal oxide film is substantially conformal across the at least one feature; exposing the transition metal oxide film to a chalcogenide precursor to convert the transition metal oxide film to a transition metal dichalcogenide film, the chalcogenide precursor being H ２ exposing the transition metal oxide film to a SiO 2 film, the transition metal dichalcogenide film having a thickness in the range of 20 Å to 30 Å; Including, The method wherein the substrate surface is maintained at a temperature within a range of about 350°C to about 450°C.

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