Molybdenum filling for 3D NAND and other applications

Abstract

To provide a method for providing a substrate having one or more features, each having at least one opening and an interior region fluidly accessible through the at least one opening.SOLUTION: A method for filling a feature with molybdenum (Mo) includes depositing a first Mo layer in a feature having an opening and an interior, and non-conformally processing a first layer such that an area near the opening is preferentially processed relative to an area in the interior. In some embodiments, a second Mo layer is deposited over the processed first layer. An embodiment of the method for filling a feature with Mo includes controlling the Mo precursor flux to transition between conformal and non-conformal filling.SELECTED DRAWING: Figure 3

Description

[Background technology]

[0001] [Incorporated by reference] PCT applications are being filed contemporaneously herewith as a part of this application. Each application to which this application claims the benefit or priority of a contemporaneously filed PCT application is hereby incorporated by reference in its entirety for all purposes.

[0002] The deposition of materials, including tungsten-containing materials, is an integral part of many semiconductor manufacturing processes. These materials may be used for horizontal interconnects, vias between adjacent metal layers, and contacts between metal layers and devices. In an example of deposition, a tungsten layer may be deposited on a titanium nitride (TiN) barrier layer to form a TiN / W bilayer by a CVD process using WF6. However, as devices shrink and more complex patterning methods are used in the industry, the deposition of tungsten thin films has become a challenge. The continued reduction in feature size and film thickness brings various challenges to TiN / W stacked films. These include high resistance of the films and degradation of TiN barrier properties. Deposition in complex high aspect ratio structures such as 3D NAND structures is particularly challenging.

[0003] The Background Art provided herein is provided to present the contents of the present disclosure generally, and the inventions of the presently named inventors are not admitted expressly or impliedly as prior art to the present disclosure to the extent that they are described in this Background Art section and in a descriptive manner that is not prior art at the time of filing. Summary of the Invention

[0004] One aspect of the disclosure relates to a method that includes providing a substrate having one or more features, each of the one or more features having at least one opening and an interior region fluidly accessible through the at least one opening; depositing a first layer of molybdenum in the one or more features; and non-conformally processing the first layer such that portions of the first layer near the at least one opening of the one or more features are preferentially processed relative to portions of the first layer deeper in the interior region of the feature.

[0005] In some embodiments, non-conformally processing the first layer comprises non-conformally inhibiting the first layer, hi some embodiments, non-conformally processing the first layer comprises non-conformally etching the first layer.

[0006] In some embodiments, treating the first layer is performed during deposition of the first layer of molybdenum. In some such embodiments, the method includes exposing the one or more features to a molybdenum precursor under conditions such that the flux or concentration of the precursor is near at least one opening of the one or more features. In some such embodiments, the molybdenum precursor is a molybdenum oxyhalide. In some such embodiments, the molybdenum oxyhalide has a lower growth rate near the one or more openings of the one or more features than interior regions due to an etching reaction. In some such embodiments, the molybdenum oxyhalide has a lower growth rate near the one or more openings of the one or more features than interior regions due to an inhibition treatment.

[0007] In some embodiments, the step of treating the first layer is performed after the first layer of molybdenum is deposited.

[0008] In some embodiments, treating the first layer comprises exposing the first layer to an inhibitor chemical. In some embodiments, the inhibitor chemical is a nitrogen-containing chemical. In some such embodiments, treating the first layer comprises exposing the first layer to either or both of hydrogen gas and a molybdenum precursor after exposing the first layer to the nitrogen-containing chemical.

[0009] In some embodiments, treating the first layer includes exposing the first layer to an etching chemical. In some such embodiments, the etching chemical is a halogen-containing chemical. In some such embodiments, treating the first layer includes purging a chamber housing the substrate after exposing the first layer to the halogen-containing chemical.

[0010] In some embodiments, treating the first layer comprises exposing the first layer to a nitrogen-containing compound. In some embodiments, treating the first layer comprises exposing the first layer to a halogen-containing compound. In some embodiments, treating the first layer comprises exposing the first layer to ammonia or nitrogen trifluoride. In some embodiments, treating the first layer is a non-plasma thermal process. In some embodiments, treating the first layer is a plasma process.

[0011] In any of the above methods, the step of depositing the first layer of molybdenum may include an atomic layer deposition process using H2 as a reducing agent for a molybdenum oxyhalide precursor or a molybdenum halide precursor.

[0012] In any of the above methods, the method may further include depositing a second layer of molybdenum after non-conformally treating the first layer. In some such embodiments, depositing the second layer includes an atomic layer deposition process using H2 as a reducing agent for a molybdenum oxyhalide precursor or a molybdenum halide precursor.

[0013] According to various embodiments, the substrate has a 3D structure having a sidewall, and the one or more openings in the one or more features are openings in the sidewall. According to various embodiments, the one or more features have a closed end.

[0014] Another aspect of the present disclosure relates to a method that includes depositing a molybdenum (Mo) conformal layer in a feature using a Mo precursor at a first Mo precursor flow rate, Mo precursor partial pressure, and Mo precursor dose time, and increasing at least one of the Mo precursor flow rate, Mo precursor partial pressure, and Mo precursor dose time to increase the Mo precursor flux at the feature opening, thereby depositing a second Mo layer on the Mo conformal layer.

[0015] Another aspect of the disclosure relates to an apparatus comprising a process chamber having one or more stations each configured to hold a substrate; one or more process gas inlets for connecting to a hydrogen (H) gas source, a molybdenum precursor gas source, an inert purge gas source, and a process gas source; and a controller for controlling operation in the apparatus, the controller comprising machine-readable instructions for: (a) flowing alternating pulses of H and the molybdenum precursor into the process chamber through the one or more process gas inlets to deposit a first molybdenum layer on the substrate; (b) after (a), injecting a process gas to treat the first molybdenum layer; and (c) after (b), flowing alternating pulses of H and the molybdenum precursor into the process chamber through the one or more process gas inlets to deposit the first molybdenum layer on the substrate.

[0016] Yet another aspect of the present disclosure relates to an apparatus comprising a process chamber having one or more stations each configured to hold a substrate, one or more process gas inlets for connecting to a hydrogen (H) gas source, a molybdenum precursor gas source, an inert purge gas source, and a process gas source, and a controller for controlling operation in the apparatus, the controller comprising machine-readable instructions for: (a) injecting H and a molybdenum precursor into the process chamber through the one or more process gas inlets to deposit a first molybdenum layer on the substrate, and (b) after (a), modifying either a flow rate or a dose time or both of the Mo precursor to deposit the first molybdenum layer on the substrate.

[0017] These and other aspects are further described below with reference to the figures. [Brief description of the drawings]

[0018] [Figure 1A] 1 illustrates an exemplary material stack including molybdenum (Mo) in accordance with various embodiments. [Figure 1B] 1 illustrates an exemplary material stack including molybdenum (Mo) in accordance with various embodiments.

[0019] [Figure 2A] 1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments. [Figure 2B] 1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments. [Figure 2C] 1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments. [Figure 2D] 1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments. [Figure 2E] 1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments. [Figure 2F] 1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments. [Figure 2G]1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments. [Figure 2H] 1A-1D are diagrams of various exemplary structures onto which molybdenum may be deposited according to disclosed embodiments.

[0020] [Diagram 3] 1 is a process diagram illustrating filling a structure with molybdenum according to various embodiments.

[0021] [Figure 4] An exemplary process performed to fill a 3D NAND structure with molybdenum.

[0022] [Diagram 5] Another exemplary process performed to fill a 3D NAND structure with molybdenum.

[0023] [Figure 6A] 1 is a process diagram illustrating operations in treating a molybdenum film in accordance with various embodiments.

[0024] [Figure 6B] FIG. 1 illustrates an example structure with narrow, dense and wide, sparse features and how controlling the molybdenum precursor flux can vary the step coverage of the molybdenum film.

[0025] [Figure 6C] 1 is a process diagram illustrating operations in molybdenum filling of a structure according to various embodiments.

[0026] [Figure 6D] 2 is a graph showing deposited molybdenum thickness as a function of molybdenum precursor flow rate.

[0027] [Figure 7] An exemplary apparatus that can be used to perform the methods described herein.

[0028] [Figure 8] FIG. 1 is a process diagram showing operations in an ALD method for forming a molybdenum film.

[0029] [Figure 9] FIG. 2 is a process diagram illustrating operations in a process for forming a molybdenum layer using a reducing agent layer.

[0030] [Figure 10] An exemplary apparatus that can be used to perform the methods described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In the following description, certain specific details are set forth in order to provide a thorough understanding of the present embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with specific embodiments, it will be understood that they are not intended to limit the disclosed embodiments.

[0032] In the following description, certain specific details are set forth in order to provide a thorough understanding of the present embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with specific embodiments, it will be understood that they are not intended to limit the disclosed embodiments.

[0033] Provided herein is a method for filling features with molybdenum (Mo) that may be used in logic and memory applications. FIGS. 1A and 1B are diagrams of an exemplary material stack including Mo, according to various embodiments. FIGS. 1A and 1B show the order of materials in a particular stack, which may be used in suitable structures and applications, as further described below with respect to FIGS. 2A-2J. In the example of FIG. 1A, a substrate 102 has a Mo layer 108 deposited thereon. The substrate 102 may be a silicon semiconductor wafer or other semiconductor wafer (e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer), including wafers having one or more material layers (such as deposited dielectric, conductive, or semiconductive materials). The method may also be used to form metal stack structures on other substrates, such as glass, plastic, and the like.

[0034] In FIG. 1A, above the substrate 102 is a dielectric layer 104. The dielectric layer 104 may be deposited directly on the semiconductor (e.g., Si) surface of the substrate 102, or there may be any number of intervening layers. Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, with specific examples including doped or undoped SiO2 and Al2O3 layers. Also in FIG. 1A, a diffusion barrier layer 106 is disposed between the Mo layer 108 and the dielectric layer 104. Examples of diffusion barrier layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten nitride (WN), and tungsten carbonitride (WCN). Further diffusion barrier examples are multi-component Mo-containing films as further described below. The Mo layer 108 is the main conductor of the structure. In some embodiments, the Mo layer 108 may include multiple bulk layers deposited at different conditions. The Mo layer 108 may or may not include a Mo nucleation layer. Additionally, in some embodiments, the Mo layer 108 may be deposited over a growth-initiation layer that includes another material, such as a tungsten (W) growth-initiation layer or a W-containing growth-initiation layer.

[0035] 1B shows another example of a material stack. In this example, the stack includes a substrate 102, a dielectric layer 104, and a Mo layer 108 deposited directly on the dielectric layer 104 without an intervening diffusion barrier layer. The Mo layer 108 is as described with respect to FIG. 1A. Using Mo as the main conductor, which has a shorter electron mean free path than W, results in a thin film with low resistance.

[0036] Although Figures 1A and 1B show examples of metal stacks, the methods and resulting stacks are not so limited. For example, in some embodiments, Mo may be deposited directly onto a Si or other semiconductor substrate, with or without an initiation layer. Figures 1A and 1B show examples of material ordering in certain stacks, which may be used in any suitable structure and application, as further described below with respect to Figures 2A-2J.

[0037] The methods described herein are performed on a substrate, which may be contained within the chamber. The substrate may be a silicon semiconductor wafer or other semiconductor wafer (e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer), including wafers having one or more layers of material, such as dielectric, conductive, or semiconductive materials, deposited thereon. The methods are not limited to semiconductor substrates and may be performed to fill any feature with molybdenum.

[0038] The substrate may have features, such as vias or contact holes, characterized by one or more of a narrow and / or concave opening, a constriction in the feature, and a high aspect ratio. The features may be formed in one or more of the above layers. For example, the features may be formed at least partially in a dielectric layer. In some embodiments, the features may have an aspect ratio of at least about 2:1, at least about 4:1, at least about 6:1, at least about 10:1, at least about 25:1, or more. One example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate.

[0039] FIG. 2A depicts a diagram of an exemplary DRAM structure having a Mo buried wordline (bWL) 208 in a silicon substrate 202. The Mo bWL is formed in a trench etched in the silicon substrate 202. Along the trench is a conformal barrier layer 206 and an insulating layer 204 disposed between the conformal barrier layer 206 and the silicon substrate 202. In the example of FIG. 2, the insulating layer 204 may be a gate oxide layer formed from a high-k dielectric material such as a silicon oxide or silicon nitride material. In some embodiments disclosed herein, the conformal barrier layer is a TiN layer or a tungsten-containing layer such as WN or WCN. In some embodiments, if TiN is used as the barrier, there may be a conformal tungsten-containing growth initiation layer between the conformal barrier layer 206 and the Mo bWL 208. Alternatively, the Mo bWL 208 may be deposited directly on the TiN or other diffusion barrier. In some embodiments, either or both of the layers 204 and 206 are not present.

[0040] The bWL shown in Figure 2A is an example of a structure that includes a Mo fill layer. During bWL fabrication, Mo is deposited into features that may be defined by etched recesses in silicon substrate 202 that conformally follow layers 206 and 204, if present.

[0041] 2B-2H are further illustrations of various exemplary structures on which Mo may be deposited according to disclosed embodiments. FIG. 2B shows an exemplary cross-sectional view of a vertical feature 201 to be filled with Mo. The feature may comprise a feature hole 205 in a substrate 202. The hole 205 or other feature may have a consistent dimension near the opening (e.g., an opening diameter or line width of about 10 nm to 500 nm, such as about 25 nm to about 300 nm). The feature hole 205 may be referred to as an unfilled feature, or simply a feature. The feature 201, and any feature, may be characterized in part by an axis 218 that extends through the length of the feature, with vertical features having a vertical axis and horizontal features having a horizontal axis.

[0042] In some embodiments, the features are wordline features in a 3D NAND structure. For example, the substrate may include a wordline structure having any number (e.g., 50-150) of wordlines with vertical channels at least 200 Å deep. Another example is a trench in the substrate or layer. The features may have any depth. In various embodiments, the features may have an underlayer, such as a barrier layer or an adhesion layer. Non-limiting examples of underlayers include dielectric layers and conductive layers (e.g., silicon oxide, silicon nitride, silicon carbide, metal oxide, metal nitride, metal carbide, and metal layers).

[0043] FIG. 2C illustrates an example of a feature 201 having a reentrant shape. A reentrant shape is a shape that tapers from the bottom, closed end, or interior of the feature toward the feature opening. According to various embodiments, the shape may taper at the feature opening and / or include a protrusion. FIG. 2C illustrates an example of the latter, where the underlayer 213 is along the sidewall or interior surface of the feature hole 105. The underlayer 213 may be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, combinations thereof, or other applicable materials. Non-limiting examples of underlayers may include dielectric layers and conductive layers (e.g., silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers). In certain embodiments, the underlayer may be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the underlayer does not include tungsten. In some embodiments, the underlayer does not include molybdenum. Underlayer 213 forms an overhang 215 such that it is thicker near the opening of feature 201 than inside feature 201 .

[0044] In some embodiments, features having one or more internal constrictions may be filled. FIG. 2D shows an exemplary diagram of various filled features having constrictions. Examples (a), (b), and (c) of FIG. 2D each have a constriction 209 at the midpoint of the feature. The constriction 209 may be, for example, about 15 nm to 20 nm wide. The constriction may cause pinch-off during deposition of tungsten or molybdenum into the feature using conventional techniques, preventing the deposited metal from further depositing beyond the constriction before a portion of the feature is filled, resulting in a void in the feature. Example (b) further has a liner / barrier overhang 215 at the feature opening. Such overhangs may also be potential pinch-off points. Example (c) has a constriction 212 further away from the field region than the overhang 215 of example (b).

[0045] Horizontal features such as 3D memory structures can also be filled. FIG. 2E shows an example of a horizontal feature 250 having a waist 251. For example, the horizontal feature 250 can be a wordline in a 3D NAND (also called vertical NAND or VNAND) structure. In some embodiments, the waist can be due to the presence of pillars in the 3D NAND structure or other structures. FIG. 2F depicts a cross-sectional side view of a 3D NAND structure 210 (formed on a silicon substrate 202) having a VNAND stack (left 225 and right 226), a central vertical structure 230, and multiple stacked horizontal features 220 with openings 222 on opposing sidewalls 240 of the central vertical structure 230. It should be noted that while FIG. 2F depicts two "stacks" of the depicted 3D NAND structure 210 that together form a "trench-like" central vertical structure 230, in certain embodiments there may be more than one "stack" arranged side-by-side and extending spatially parallel to one another, with the gap between each adjacent pair of "stacks" forming the central vertical structure 230 as explicitly depicted in FIG. 2F. In this embodiment, the horizontal features 120 are 3D memory wordline features that are fluidly accessible from the central vertical structure 230 through the openings 222. Although not explicitly depicted in the figure, the horizontal features 220 present in both the depicted 3D NAND stacks 225 and 226 (i.e., the left 3D NAND stack 225 and the right 3D NAND stack 226) in FIG. 2F are also accessible (at the left and right ends, not shown) through similar vertical structures formed by additional 3D NAND stacks from the other side of the stacks (at the left and right ends, respectively). That is, 3D NAND stacks 225 and 226 each include a stack of wordline features that are fluidly accessible from both sides of the 3D NAND stack through a central vertical structure 1230. In the particular example shown diagrammatically in FIG. 2F, each 3D NAND stack includes six pairs of stacked wordlines, although in other embodiments, a 3D NAND memory layout may include any number of pairs of vertically stacked wordlines.

[0046] Word line features in a 3D NAND stack are typically formed by depositing alternating layers of silicon oxide and silicon nitride layers, then selectively removing the nitride layers leaving a stack of oxide layers with gaps between them. These gaps are the word line features. Any number of word lines may be stacked vertically in such a 3D NAND structure, so long as there is a technology that allows for their formation and that lends itself to successfully achieving (substantially) void-free filling of the vertical features. Thus, for example, a VNAND stack may have 2-256 horizontal word line features, or 8-128 horizontal word line features, or 16-64 horizontal word line features, etc. (it is understood that the stated ranges include their endpoints).

[0047] FIG. 2G depicts a cross-sectional top view of the same 3D NAND structure depicted in the side view of FIG. 2F, with the cross section taken at horizontal portion 260, indicated by the horizontal dashed line in FIG. 2F. The cross section of FIG. 2G depicts a series of pillars 255 extending vertically from the base of semiconductor substrate 202 to the top of 3D NAND stack 210, depicted in FIG. 1F. In some embodiments, these pillars 255 are formed of polysilicon material and are structurally and functionally important to 3D NAND structure 210. In some embodiments, such polysilicon pillars may function as gate electrodes for stacked memory cells formed within the pillars. The top view of FIG. 2G depicts that pillars 255 form a constriction in opening 222 for wordline feature 220. That is, the possibility of fluid access of wordline feature 220 from central vertical structure 230 through opening 222 (indicated by arrow in FIG. 2G) is suppressed by pillars 255. In some embodiments, the horizontal gap size between adjacent polysilicon pillars is about 1-20 nm. This reduction in fluid accessibility increases the difficulty of uniformly filling the wordline features 120 with material. The structure of the wordline features 220 and the challenges of uniformly filling them with molybdenum material due to the presence of the pillars 255 are further explained in Figures 2H, 2I, and 2J.

[0048] FIG. 2H shows a vertical cut of a 3D NAND structure similar to that shown in FIG. 2F, but now focused on a pair of wordline features 220, and further illustrates a filling process that results in the formation of a void 275 in the filled wordline feature 120. FIG. 1I also shows a void 175 diagrammatically, but this time with a horizontally cut pillar 155, similar to the horizontal cross section shown in FIG. 2G. FIG. 2J shows the deposition of molybdenum material around the necked pillar 255. This deposition results in a pinch-off of the opening 222, and no further molybdenum material can be deposited in the area of ​​the void 275. 2H and 2I, it is clear that void-free molybdenum filling relies on the movement of a sufficient amount of deposition precursor through the vertical structure 230, through the opening 222, and over the waisted pillar 255 to reach the furthest wordline feature 220 before molybdenum deposits around the pillar 255 causing pinch-off of the opening 222 and preventing further precursor movement into the wordline feature 220. Similarly, FIG. 2J shows one wordline feature 220 in cross section from above, illustrating how deposition of a generally conformal molybdenum material begins to pinch off the interior of the wordline feature 220, with the wide pillar 255 partially blocking and / or narrowing and / or constricting what would otherwise be an open path to the wordline feature 220 (note that the example in FIG. 2J represents a waist seen in plan view rather than in cross section, as it can be understood as a 2D rendering of the 3D feature of the pillar waisted structure shown in FIG. 2I).

[0049] Three-dimensional structures may require longer and / or more focused exposure to the precursor to fill the innermost, lowest regions. Three-dimensional structures can be particularly challenging when using molybdenum halide and / or molybdenum oxyhalide precursors due to their etching characteristics, with longer and more focused exposure allowing more etching to occur as part of the structure.

[0050] Below, an example of feature filling of horizontal and vertical features is described. Note that, at least in most cases, this example is applicable to both horizontal and vertical features. Also, in the following description, the term "lateral" may be used to generally mean a direction perpendicular to the feature axis, and the term "vertical" may be used to generally mean a direction along the feature axis.

[0051] The material distribution within a feature may be characterized by its step coverage. For purposes of this description, "step coverage" is defined as the ratio of two thicknesses (i.e., the thickness of the material inside the feature divided by the thickness of the material near the opening). For purposes of this document, the term "inside the feature" refers to the central portion of the feature located near the midpoint of the feature along the feature axis (e.g., an area between about 25% and 75% of the distance, or, in certain embodiments, an area between about 40% and 60% of the distance along the depth of the feature measured from the opening of the feature, or the edge of the feature located between about 75% and 95% of the distance along the feature axis measured from the opening). The term "near the feature opening" or "near the opening of the feature" refers to the top of the feature located within 25%, or, in some embodiments, within 10% of the edge of the opening, or other element representing the edge of the opening. A conformal film would have a step coverage of about 100%. Greater than 100% step coverage can be achieved, for example, by filling a feature with more material near the center or bottom of the feature than at the feature opening.

[0052] FIG. 3 is a process diagram illustrating operations in filling a structure with molybdenum, according to various embodiments. First, in operation 302, a molybdenum (Mo) film is deposited in the structure. This operation may be referred to as Dep1. In many embodiments, operation 302 is generally a conformal deposition along exposed surfaces of the structure. For example, in a 3D NAND structure as shown in FIG. 2F, the Mo film is along the word line features 220. According to various embodiments, the Mo film is deposited using an ALD process to achieve good conformality. A further description of the ALD process for Mo is provided below. In some embodiments, after operation 302, the feature is not closed with Mo, but is open enough to allow additional reactant gases to enter the feature in subsequent depositions.

[0053] Next, in operation 304, the deposited film is processed non-conformally, where non-conformal processing refers to processing that occurs preferentially at or near the openings of the features rather than inside the features. In a 3D NAND structure, the processing can be vertically conformal, such that the bottom wordline features are processed to approximately the same extent as the top wordline features, but is non-conformal in that the interiors of the wordline features are not processed or are processed to a significantly lesser extent than the feature openings.

[0054] Nucleation inhibition inhibits subsequent molybdenum nucleation at the treated surface. Nucleation inhibition includes one or more of deposition of an inhibiting film, reaction of a treatment species with the Mo film to form a compound film (e.g., Mo2N), and adsorption of an inhibiting species. During a subsequent deposition operation, there is a nucleation delay on the inhibited portions of the underlying film relative to the uninhibited or less inhibited portions. Etching removes the deposited film at the treated surface. This involves reacting an etching species with the molybdenum film to form gaseous by-products, which are then removed. Other etching methods may be performed, including atomic layer etching. Operation 304 may be a plasma or non-plasma operation. If it is a non-plasma operation, it may be a fully thermal operation, or it may be activated by some other energy, such as UV.

[0055] Nitrogen acts as an inhibition species and halogen (e.g., fluorine and chlorine) species act as etchants. To perform a full inhibition process, operation 304 may include exposing the Mo film to a nitrogen-containing chemical that does not contain a halogen. To perform a full etching process, operation 304 may include exposing the Mo film to a halogen-containing chemical that does not contain nitrogen. In some embodiments, other inhibition chemistries (e.g., oxygen-containing chemicals) may be used. Exposing the film to both nitrogen-containing and halogen-containing chemicals (e.g., nitrogen trifluoride (NF3) or ammonia / fluorine (NH3 / F2)) allows for both inhibition and etching.

[0056] According to various embodiments, operation 302 may be performed in the same processing chamber or in different processing chambers. If performed in the same chamber, operation 302 may be performed in a single station chamber or a multi-station chamber. In a multi-station chamber, in some embodiments, operation 302 may be performed in a first station and operation 304 may be performed in a second station. As described further below, operation 304 may be a continuous flow process or a pulsed process. In the latter case, different gases may be pulsed in succession to adjust the process.

[0057] After operation 304, a second deposition is performed in operation 306. The second deposition may be performed with an ALD process or a CVD process. An ALD process is described further below in connection with FIG. 8 and generally includes alternating pulses of reactants for surface-mediated reactions. In CVD methods, reactants are generally flowed so that they are in the gas phase in the reaction chamber. CVD may include gas phase reactions. In deposition on 3D NAND structures, an ALD process may be used to enable excellent step coverage across the structure. Gases reach the interior of the feature more easily due to the effect of the process. After the etching process, the film deposited near the entrance of the feature is removed to allow more space for gases to reach the interior of the feature and prevent pinch-off. In some embodiments, enough Mo film may be removed so that the underlying surface is fully or partially exposed to increase the nucleation delay in these regions. After the inhibition process, the nucleation delay increases and allows the inside-out fill process. Operation 306 is referred to as a Dep2 process and may complete the filling of the structure in some embodiments. In other embodiments, one additional processing / deposition operation may be performed. The pressure and process gas flow rates may be adjusted to adjust the lateral non-conformity in the wordline. High chamber pressure and low process gas flow rates (and / or concentrations) facilitate processing at the openings of the wordline features versus processing inside the wordline features. Thus, in some embodiments, the chamber pressure may be decreased from operation 602 to operation 604. Example chamber pressures are between 3 Torr and 40 Torr.

[0058] To achieve lateral non-conformity while still having top-to-bottom uniformity, a fill reservoir may be used to deliver the gas. These are described below in connection with FIG. 7 and may be particularly useful for deep structures (e.g., 7-10 microns deep). In some embodiments, the deposition and non-conformal processing may be performed simultaneously. For example, operations 302 and 304 of FIG. 3 may be performed simultaneously. Depending on various embodiments, a subsequent deposition (e.g., Dep2) may be performed, or operations 302 and 304 may be sufficient to fill the feature. As noted above, molybdenum halides and molybdenum oxylides may be used as etch gases. In some embodiments, these may be used as deposition and etch gases. By appropriately controlling the concentration of the deposition reactants in the feature, the amount of deposition and etching can be controlled at various stages of the feature. In a particular example, molybdenum oxychloride (MoO x Cl y (x and y are numbers greater than 0 that form a stable compound) may be used as both a Mo deposition gas and an etch gas, with a net deposition rate toward the interior of the feature and a low deposition rate or net etch rate toward the feature opening. As will be further explained below in connection with FIG. 6D, the overall growth rate is influenced by the flux or concentration of the precursor at the surface. High MoO x Cl y A higher MoO flux can result in more etching in some embodiments. x Cl y In flux, the precursor concentration inside the feature is lower than near the opening or field regions, allowing bottom-up growth. Precursor dose time, precursor flow rate, chamber pressure, and precursor partial pressure can be used to adjust the precursor flux.

[0059] Inhibition treatment may be performed non-conformally during Mo deposition. For example, the Mo precursor may inhibit deposition if not completely reduced. In one example, at high MoO2Cl2 flux, the concentration of MoO2Cl2 is higher at the opening of the feature than inside the feature. If the H2 co-reactant flow is low enough that MoO2Cl2 cannot be reduced at the feature opening, MoO2Cl2 can act as an inhibitor.

[0060] FIG. 4 depicts an exemplary process performed to fill a 3D NAND structure with molybdenum. In FIG. 4, a cross-sectional view of a single wordline of the 3D NAND structure is shown (as in the example of FIG. 2J, the wordline feature in FIG. 4 shows the waist of the pillar seen in plan view rather than cross-sectional view to show the waist). At 470, the wordline feature is shown after Dep1 process. Underlayer 406 is shown, which may be, for example, a barrier layer. Mo conformal film 405 lines the feature surface. In some embodiments, Mo conformal film 405 is deposited directly on a dielectric surface, such as an aluminum oxide surface or a silicon oxide surface. Mo layer 405 may be a nucleation layer, a nucleation bulk layer, or a bulk layer. The feature is then exposed to an inhibition chemistry at 471 to inhibit portion 465. In this example, portion 465 to the waist of the pillar 451 is inhibited while the interior surface of 452 is not inhibited. Inhibition can include, for example, exposure to NH3 gas or to a remote or in-situ plasma generated from gases (N2, H2, forming gas, NH3, O2, CH4, etc.). A process is then performed to selectively deposit molybdenum according to the inhibition profile. Bulk Mo 408 is preferentially deposited at 472 on the uninhibited portions of Mo layer 405 to fill the hard to fill area behind the waist. In this example, bulk deposition continues at 473 to fill the remainder of the feature with bulk Mo 408.

[0061] In some embodiments, the sequence shown in 471 and 472 may be performed in one operation as described above using a Mo precursor that can act as a suppressor at the feature opening during deposition.

[0062] FIG. 5 depicts another exemplary process performed to fill a 3D NAND structure with molybdenum. In the example of FIG. 5, an underlayer 506 is shown, which may be, for example, a barrier layer. A Mo conformal film 505 lines the feature surface. In some embodiments, the Mo conformal film 505 is deposited directly on a dielectric surface, such as an aluminum oxide surface or a silicon oxide surface. The Mo layer 505 may be a nucleation layer, a nucleation bulk layer, or a bulk layer. This is followed at 571 by a nonconformal etch (with high selectivity to protect the underlayer 506, if present). For example, a nonconformal etch with high Mo:TiN selectivity may be performed due to a TiN underlayer. The nonconformal etch results in the Mo layer 505 being thinned or completely removed in the feature opening 522, while remaining intact in the interior 552 of the feature. Bulk Mo 508 is then deposited at 572 on the remaining portion of the Mo layer 405 to fill the difficult to fill area behind the waist. In this example, bulk deposition continues to fill the remainder of the feature with bulk Mo 508 at 573. In some embodiments, the dep-etch-dep operations may be repeated to fill the feature. Depending on various embodiments, each subsequent deposition operation may or may not include the deposition of a nucleation layer. In some embodiments, this process may include an inhibition effect.

[0063] In some embodiments, the sequence shown in 571 and 572 may be performed in one operation as described above using a Mo precursor that can act as an etchant in the feature opening during deposition.

[0064] In some embodiments, Dep1 and Dep2 are each used to deposit a bulk Mo layer, with Dep1 being used to deposit a conformal layer in the examples of Figures 4 and 5 and Dep2 being used to fill the features.

[0065] In some embodiments, the Mo conformal layer may be characterized as low resistivity, and in some embodiments, low stress and / or low fluorine. Because the wordline features are not filled (except for a nucleation layer, if one is deposited), a relatively fast deposition technique may be used. In some embodiments, this involves alternating pulses of a Mo-containing precursor and hydrogen (H2) or other reducing agent to deposit the first tungsten layer in an ALD process. A purge operation may separate the pulses. To increase throughput, a relatively short pulse time may be used for deposition.

[0066] A second bulk layer may be deposited using a second set of conditions. Similar to the first bulk layer, the second bulk layer may be a low resistivity layer, and in some embodiments, a low stress and / or low fluorine layer. In some embodiments, operation 306 includes a longer pulse time and a longer purge time than operation 302. In certain embodiments, the pulse time of the Mo-containing precursor may be longer. Increasing the pulse time and / or purge time may facilitate diffusion of the reactant into the wordline. In some embodiments, the temperature may be changed from operation 302 to operation 306 (e.g., a higher temperature may be used to speed up the reaction time). In some embodiments, a lower temperature may be used to allow the reactant to diffuse into the wordline features before reacting. In some embodiments, the second set of conditions may include a change in flow rate. For example, the flow rate of the Mo-containing precursor and / or the reducing agent may be increased.

[0067] A third bulk Mo layer may be deposited under different conditions. This layer may be characterized as a capping layer that may be removed in a next step and deposited on a sidewall, such as sidewall 240, in the 3D NAND structure of FIG. 2F. This layer may be characterized by low roughness. High resistivity and / or high fluorine concentration may be tolerated because molybdenum is removed. The third set of conditions may include either faster timing, use of CVD rather than ALD, and introduction of nitrogen (N2) during or between the flows of one or more reactant gases if ALD is used with a shorter pulse time than in operation 405.

[0068] FIG. 6A is a process diagram showing operations in the treatment of Mo films according to various embodiments. First, in operation 602, the surface is exposed to a halogen-containing chemical and / or a nitrogen-containing chemical. In operation 602, nitrogen is the inhibitor chemical, and other inhibitor chemicals may be used in addition to or instead of nitrogen, if desired. For etching, fluorine-containing and chlorine-containing chemicals are used. Operation 602 may be a continuous flow or pulsed operation, and may be a plasma operation, or a thermal operation, or a non-plasma operation. Other activation energies may be applied.

[0069] Examples of nitrogen-containing gases for inhibition include NF3, NH3, nitrogen (N2), and hydrazine (N2H4). Other nitrogen-containing gases may be used, but in many embodiments, oxygen-containing compounds (e.g., NO2) are avoided. The gas may be flowed into the chamber in a non-plasma thermal process, or may be used to generate a plasma with a remote plasma generator or an in-situ plasma generator. In some embodiments, less reactive gases (e.g., N2) may require activation of the plasma for effective inhibition.

[0070] Examples of halogen-containing gases for etching include NF3, F2, hydrogen fluoride (HF), chlorine (Cl2), chlorine trifluoride (ClF3), and other Cl- or F-containing gases. Molybdenum halide and molybdenum oxyhalide gases may also be used. These gases will etch the film if there is no reducing agent to react with.

[0071] Next, in operation 604, there may be a purge with a non-halogen gas. An inert gas such as Ar or He may be used. N2 may also be used. The purge is a non-plasma process that can remove chlorine or fluorine species from the surface. In some embodiments (e.g., embodiments in which the substrate is not exposed to chlorine or fluorine species in operation 602), operation 604 may be omitted.

[0072] The surface may then be exposed to a surface morphology treatment gas in operation 606. It has been found that the inhibitory treatment can result in a "rough" surface that can adversely affect the quality of the film deposited in Dep2. The surface morphology treatment gas may be a pulsed or continuous flow of a molybdenum precursor, a reducing agent (e.g., H2), or both.

[0073] In some embodiments, operations 602-606 are repeated one or more times. For example, each operation may be performed as one pulse of a multi-cycle sequence of pulses. In another embodiment, operation 602 may be performed as a multi-cycle pulse, and either or both of operations 604 and 606 may be performed only at the end of the multi-cycle. The order of operations 604 and 606 may be reversed in some embodiments. In some embodiments, molybdenum feature fill may be performed by controlling the precursor flux to control the step coverage of the resulting fill. FIG. 6B shows an example structure with narrow, dense features 610 and wide, sparse features 620, and a diagram of how the step coverage of the molybdenum film 635 can be changed by appropriately controlling the molybdenum precursor flux (flux is the flow rate per unit area, so the flux may be increased or decreased by increasing or decreasing the flow rate into the chamber). At relatively low precursor fluxes, step coverage is poor and more Mo is deposited near the top of the feature and in the field region 630 than in the interior 640 of the feature.

[0074] As the precursor flux is increased, the deposition becomes conformal with approximately the same amount of Mo conformally deposited across the feature. This increase in step coverage seen with increased precursor flux may be due to a transition from mass transport limited growth to surface reaction limited growth.

[0075] At higher precursor fluxes, superconformality occurs in the narrow, dense features 610. Bottom-up growth, as seen in the wide, sparse features 620, shows that the Mo film 635 is at the bottom of the features 620 but not appreciably deposited on the sides of those features.

[0076] In some embodiments, the precursor flux may be changed during Mo feature fill. For example, in the first stage of Mo fill, conformal growth conditions may be used with growth in the field regions inhibited. In the next stage, the precursor flux is increased with superconformal and bottom-up growth. Multi-stage processes may be advantageously used to fill features of different sizes. FIG. 6C is a process diagram illustrating operations in molybdenum fill of a structure according to various embodiments. In the process of FIG. 6C, a Mo conformal layer is deposited in the feature (652). CVD or ALD may be used. Next, in operation 654, the precursor flux is increased to transition to bottom-up fill. To increase the precursor flux, one or more of the Mo precursor partial pressure, Mo precursor flow rate, and Mo precursor dose time may be increased. The fill can be completed in operation 656. In some embodiments, operation 656 continues with the conditions of operation 654. In other embodiments, the precursor flux may be decreased once the feature is filled to a certain point.

[0077] The growth rate of Mo is influenced by the precursor flux and precursor concentration at the surface. In some embodiments, bottom-up growth is observed under high precursor flux conditions where the precursor concentration deep inside the feature is lower than the precursor concentration in the field region and near the top of the feature. This is because high precursor flux is favorable for the deposition reaction and can result in low growth rates. A chlorine-containing Mo precursor can result in the following deposition and etch reactions, for example: MoO x Cl y +H2→Mo(s)+HCl+H2O (Mo bulk deposition by subchlorides), Mo+Cl2→MoCl y (Mo etching), and Mo+MoCl y →Mo z Cl y (Mo etching). If an underlayer (e.g., a W underlayer) is present, it may be etched under the following specific conditions: W+Cl2→WCl y(W etching), and W+WCl y →W z Cl y (W etching).

[0078] The above reactions are examples of reactions that can occur under high Mo precursor conditions. FIG. 6D is a graph showing the thickness of deposited molybdenum as a function of the flow rate of the molybdenum precursor. FIG. 6D shows how the net deposition amount of Mo decreases under high precursor flux conditions using MoOCl4 (the data in FIG. 6D is from CVD deposition of Mo, but a similar trend is seen for ALD, with a difference of 10° C. between low and high ambient temperatures). Three deposition regimes are shown: poor step coverage, conformal growth, and bottom-up growth. As can be seen in FIG. 6D, at high precursor flow rates, the net deposition amount decreases. This can cause bottom-up filling with high precursor concentration at the top of the feature (resulting in low deposition rate) and low precursor concentration within the feature (resulting in high deposition rate). As mentioned above, in lateral features such as FIG. 4 and FIG. 5, bottom-up filling (i.e., non-conformal filling) is inside-out filling, where the feature is filled from the inside to the outside.

[0079] The method may be implemented using multiple fill vessels. An exemplary apparatus is shown in FIG. 7, in which three gas sources (process gas 1, process gas 2, and purge gas) are connected to the fill vessels. In some embodiments, one or more gas sources may be connected to multiple fill vessels. The apparatus includes a gas manifold system that provides line fill to various gas distribution lines. The manifold provides process gas and purge gas to the deposition chamber through valved fill vessels. Various valves open and close to provide line fill (i.e., pressurize the distribution lines).

[0080] The use of a fill reservoir allows delivery of process gas to the bottom of high aspect ratio structures (e.g., the bottom wordlines of a 3D NAND structure). Pressurized gas flows through the showerhead and onto the wafer or other workpiece to be processed.

[0081] An example of the processing sequence is: Example 1: One or more cycles of (NF3+Ar / purge / H2+Ar) (+ indicates that the gases are flowed simultaneously into the chamber, " / " indicates separation in time); Example 2: One or more cycles of (NH3+Ar / H2+Ar), Example 3: One or more cycles of (NH3+Ar / Mo precursor+H2+Ar), and Example 4: One or more cycles of (NH3+Ar / Mo precursor+Ar) Includes. Mo deposition

[0082] To deposit molybdenum with the above method, Mo-containing precursors may be used, including molybdenum hexafluoride (MoF6), molybdenum pentachloride (MoCl5), molybdenum dioxide dichloride (MoO2Cl2), molybdenum oxide tetrachloride (MoOCl4), and molybdenum hexacarbonyl (Mo(CO)6). The Mo-containing precursor may be a halide precursor including MoF6 and MoCl5, as well as a mixed halide precursor having two or more halogens capable of forming a stable molecule. An example of a mixed halide precursor is MoCl x Br y (x and y are any numbers greater than 0 that can form a stable molecule). The organometallic precursor is Mo(X) m (L) n (As disclosed in U.S. Provisional Patent Application No. 62 / 816,648, each X is a halogen independently selected from the group consisting of F, Cl, Br, and I, each L is an organic ligand comprising an element selected from the group consisting of N, O, and S, m is selected from 1 to 4, and n is selected from 1 to 3.) Organometallic precursors such as molybdenum silylcyclopentadienyl complexes and molybdenum silylallyl complexes may be used. Mo deposition

[0083] FIG. 8 illustrates an example of an ALD method for forming a Mo film. The method according to FIG. 8 may be used, for example, in either or both of operations 302 and 306 of FIG. 3 and in any of the operations of FIG. 6C. First, in operation 805, the Mo precursor is pulsed. After the Mo precursor is pulsed, a purge 815 may occur if necessary. Argon or any inert gas may be used to purge unadsorbed precursor from the chamber. The substrate is exposed to a co-reactant 825, which may be a reducing agent for reducing the Mo precursor, or other co-reactant, to react with the Mo precursor to form elemental Mo. The reactant may be a hydrogen-containing reactant. In some embodiments, the hydrogen-containing reactant may be thermal (non-plasma) hydrogen (H2). In plasma-based processes, a remote plasma or an in-situ plasma generated from H2 may be used. A purge may be performed if necessary in 835, followed by repeating operations 805-835 until the film is fully grown. This may be a conformal film along the feature, for example a Mo conformal film 405 or 505, or a bulk layer (such as bulk Mo 408 or 508) that fills all or part of the feature.

[0084] In some embodiments, illustrated operation 302 includes depositing a Mo nucleation layer as, or as part of, a conformal layer upon which bulk Mo is deposited.

[0085] In some embodiments, the Mo nucleation layer is deposited using either or both of a boron-containing reducing agent (e.g., B2H6) and a silicon-containing reducing agent (e.g., SiH4) as co-reactants. For example, one or more S / Mo cycles (S / Mo means a silane pulse followed by a Mo-containing precursor pulse) may be used to deposit a Mo nucleation layer from which a bulk Mo layer is deposited. In another example, one or more B / Mo cycles (B / Mo means a diborane pulse followed by a Mo-containing precursor pulse) may be used to deposit a Mo nucleation layer from which a bulk Mo layer is deposited. Both B / Mo and S / Mo cycles may be used to deposit a Mo nucleation layer (e.g., x(B / Mo)+y(S / Mo), where x and y are integers). Examples of B-containing and S-containing reducing agents are shown below. In the deposition of the Mo nucleation layer, in some embodiments, the Mo-containing precursor may be a non-oxygen-containing precursor (e.g., MoF6 or MoCl5). The oxygen in the oxygen-containing precursor reacts with the silicon-containing or boron-containing reducing agent to produce an impure, highly resistive film, MoSi x O y or MoB x O y may be formed. An oxygen-containing precursor may be used with minimal oxygen contamination. In some embodiments, H2 may be used as the reducing gas instead of a boron-containing or silicon-containing reducing gas. An example of a deposition thickness for the Mo nucleation layer is 5 Å to 30 Å. Although films at the lower end of this range are not continuous, this thickness may be sufficient as long as it helps initiate continuous bulk Mo growth. In some embodiments, the reducing agent pulse may be performed at a lower substrate temperature than the Mo precursor pulse. For example, a pulse of B2H6 or SiH4 (or other boron-containing or silicon-containing reducing agent) may be performed at a temperature below 300° C., and the Mo pulse may be performed at a temperature above 300° C.

[0086] Conformal deposition may be performed directly on surfaces such as dielectric surfaces and TiN surfaces by the process illustrated in FIG. 9. Conformal deposition may be used with a W-containing starting surface or a Mo nucleation layer. In operation 902, the substrate is exposed to a reducing agent gas to form a reducing agent layer. In some embodiments, the reducing agent gas may be silane, borane, or a mixture of silane and diborane. Examples of silanes include SiH4 and Si2H6, and examples of boranes include diborane (B2H6), as well as B2H6. n H n+4 , B n H n+6 , B n H n+8 , B n H m (n is an integer between 1 and 10, and m is an integer different from m). Other boron-containing compounds (e.g., alkylboranes, alkylboranes, aminoboranes (CH3)2NB(CH2)2, carboranes (CB n H n+2 (e.g., fluorine, fluorine-containing, fluorine-containing, etc.) may be used. In some embodiments, the reducing agent layer may include silicon or silicon-containing materials, phosphorous or phosphorous-containing materials, germanium or germanium-containing materials, boron or boron-containing materials, and combinations thereof, capable of reducing the tungsten precursor. Further examples of reducing agent gases that may be used to form such layers include PH3, SiH2Cl2, and GeH4. According to various embodiments, hydrogen may or may not be flowed in the background (hydrogen can reduce the tungsten precursor, but does not function as a reducing agent in gas mixtures with sufficient amounts of stronger reducing agents, such as silane and diborane).

[0087] In some embodiments, the reducing agent gas is a mixture containing a small amount of a boron-containing gas (such as diborane) and another reducing agent. The addition of a small amount of a boron-containing gas can significantly affect the decomposition and sticking coefficient of the other reducing agent. It is noted that a process of sequentially exposing the substrate to two reducing agents (e.g., silane and diborane) may be performed. However, flowing a mixture of gases can facilitate the addition of a small amount of a minority gas (e.g., a silane:diborane ratio of at least 100:1). In some embodiments, a carrier gas may be flowed. In some embodiments, a carrier gas (such as nitrogen (N2), argon (Ar), helium (He), or other inert gas) may be flowed during operation 902.

[0088] In some embodiments, the reducing agent layer may include elemental silicon (Si), elemental boron (B), elemental germanium (Ge), or mixtures thereof. For example, the reducing agent layer may include Si and B. The amount of B may be adjusted to achieve a high deposition rate but low resistance reducing agent layer. In some embodiments, the reducing agent layer may have 5%-80% B (e.g., 5%-50% B, 5%-30%, or 5%-20% B), with the remainder consisting primarily of Si and possibly H. Hydrogen atoms (e.g., SiH x , B.H. y , GeH z , or mixtures thereof) may be present (wherein x, y, and z may independently be between 0 and a number less than the stoichiometric equivalent of the corresponding reducing agent compound).

[0089] In some embodiments, the reducing agent layer may have different compositions through its thickness. For example, the reducing agent layer may have 20% B at its bottom and 0% B at its top. The total thickness of the reducing agent layer may be between 10 Å and 50 Å, and in some embodiments, between 15 Å and 40 Å, or between 20 Å and 30 Å. The reducing agent layer conformally conforms to the features.

[0090] The substrate temperature during operation 902 may be maintained at a temperature T1 at which the film becomes conformal. If the temperature is too high, the film will not conform to the shape of the underlying structure. In some embodiments, step coverage of greater than 90% or 95% is achieved. For silane, diborane, and silane / diborane mixtures, conformality is excellent at 300° C. and will degrade at temperatures of 400° C. or higher. Thus, in some embodiments, the temperature in operation 902 is at most 350° C., or at most 325° C., at most 315° C., or even at most 300° C. In some embodiments, temperatures below 300° C. are used. For example, the temperature may be as low as 200° C.

[0091] Operation 902 may be performed for any suitable duration, in some examples, example durations include between about 0.25 seconds and about 30 seconds, between about 0.25 seconds and about 20 seconds, between about 0.25 seconds and about 5 seconds, or between about 0.5 seconds and about 3 seconds.

[0092] In operation 904, the chamber is purged as needed to remove excess reducing agent that did not adsorb to the surface of the substrate. Purging may be performed by flowing an inert gas at a predetermined pressure to reduce the chamber pressure and repressurizing the chamber before beginning another gas exposure. Examples of inert gases include nitrogen (N2), argon (Ar), helium (He), and mixtures thereof. Purging may be performed for a period of about 0.25 seconds to about 30 seconds, about 0.25 seconds to about 20 seconds, about 0.25 seconds to about 5 seconds, or about 0.5 seconds to about 3 seconds.

[0093] In operation 906, the substrate is exposed to a Mo-containing precursor at a substrate temperature T2. Examples of Mo-containing compounds are described above and include chlorides and oxychlorides. Use of oxygen-containing precursors may result in impurity incorporation and high resistance. However, if oxygen is incorporated, a very thin non-continuous reducing agent layer may be used for acceptable resistance. In some embodiments, a carrier gas (such as nitrogen (N2), argon (Ar), helium (He), or other inert gas) may be flowed during operation 906. Example temperatures are 500°C to 700°C.

[0094] Operation 906 may be performed for any suitable duration. In some embodiments, operation 906 may include a soak of a Mo-containing precursor, and in some embodiments, may include a continuous pulse of a Mo-containing precursor. Depending on various embodiments, operation 906 may or may not be performed in the presence of H2. If H2 is used, in some embodiments, H2 and the Mo-containing precursor may be added in an ALD-type mode. For example, H2 pulse, argon purge, Mo-containing precursor pulse with or without H2 in the background, argon purge, are repeated.

[0095] The substrate temperature T2 is high enough for the Mo-containing precursor to react with the reducing agent layer to form elemental Mo. The entire reducing agent layer is converted to Mo. In some embodiments, the temperature is at least 450° C., and may be at least 550° C. to obtain 100% or near 100% conversion. The resulting features are now aligned with the Mo conformal film. The conformal film may be 10 Å to 50 Å, and in some embodiments, 15 Å to 40 Å, or 20 Å to 30 Å. In general, the conformal film will be about the same thickness as the reducing agent layer. In some embodiments, the conformal film may be up to 5% thicker than the reducing agent layer due to volume expansion during conversion.

[0096] Although the following description is specific to molybdenum filling, aspects of the disclosure may also be implemented in filling features with other materials, for example, the processing sequence described in Figure 6 may be implemented with a feature fill process using a tungsten-containing material, a cobalt-containing material, or a ruthenium-containing material. Device

[0097] Any suitable chamber may be used to practice the embodiments of the present disclosure. Examples of deposition apparatus include various systems, such as, for example, the ALTUS® and ALTUS® Max available from Lam Research Corporation, Fremont, Calif., or various other commercially available processing systems.

[0098] In some embodiments, the first deposition may be performed in a first station that is one of two, five, or more deposition stations located in a single deposition chamber. Thus, for example, hydrogen (H2) and tungsten chloride (MoO2Cl2) may be introduced in alternating pulses to the surface of the substrate in the first station using individual gas supply systems that form a local atmosphere at the surface of the semiconductor substrate. Another station may be used for processing, and a third and / or fourth station may be used for subsequent ALD bulk fill.

[0099] 10 is a diagram of a process system suitable for performing a deposition process according to embodiments. The system 1000 includes a transfer module 1003. The transfer module 1003 provides a clean pressurized environment to minimize the risk of contamination as the substrate being processed moves between the various reactor modules. The transfer module 1003 is fitted with a multi-station reactor 1109 capable of performing ALD, processing, and CVD according to various embodiments. The multi-station reactor 1009 may include multiple stations 1011, 1013, 1015, and 1017 that can sequentially perform operations according to the disclosed embodiments. For example, multi-station reactor 1009 may be configured such that station 1011 performs a molybdenum nucleation layer deposition using a chlorine-containing molybdenum precursor and a boron-containing or silicon-containing reducing agent, station 1013 performs an ALD molybdenum bulk deposition of a conformal layer using H2 as the reducing agent, station 1015 performs process operations, and station 1017 performs a bulk ALD fill.

[0100] The station may include a heated pedestal or substrate support, one or more gas inlets or a showerhead or distribution plate. An example of a deposition station is shown in Figure 7 above.

[0101] Returning to FIG. 10, the transfer module 1003 may be fitted with one or more single or multi-station modules 1007 capable of performing plasma or chemical (non-plasma) pre-clean, other deposition operations, or etching operations. The modules may be used for various processes, such as substrate preparation for a deposition process. The system 1000 also includes one or more wafer source modules 1001 where wafers are stored before or after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 1019 may initially retrieve the wafer from the source module 1001 to a load lock 1021. A wafer transfer device (typically a robot arm device) in the transfer module 1003 moves the wafer from the load lock 1021 to and between modules attached to the transfer module 1003.

[0102] In various embodiments, a system controller 1029 is used to control process conditions during deposition. The controller 1029 will typically include one or more memory devices, as well as one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, a stepper motor controller board, etc.

[0103] The controller 1029 may control all operations of the deposition apparatus. The system controller 1029 executes system control software that includes sets of instructions for controlling timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other parameters of a particular process. In some embodiments, other computer programs stored in a memory device associated with the controller 1029 may be used.

[0104] Typically, there will be a user interface associated with the controller 1029. The user interface may include a display screen, software screens for graphics of equipment and / or process conditions, and user input devices (pointing device, keyboard, touch screen, microphone, etc.).

[0105] The system control logic may be configured in any suitable manner. In general, logic may be designed or configured in hardware and / or software. Instructions for controlling the drive circuitry may be hard-coded or provided as software. The instructions may be provided by "programming." Such programming is understood to include any form of logic, including logic hard-coded in digital signal processors, application specific integrated circuits, and other devices that have specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that can be executed on a general purpose processor. The system control software may be coded in any suitable computer readable programming language.

[0106] The computer program code for controlling the germanium-containing reducing agent pulses, hydrogen flow, tungsten-containing precursor pulses, and other processes in the process sequence may be written in any suitable computer readable programming language (e.g., assembly language, C, C++, Pascal, Fortran, or other). The compiled object code or script is executed by the processor to perform the tasks identified in the program. The program code may also be hard coded as shown.

[0107] The controller parameters relate to process conditions such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters may be provided to a user in the form of a recipe or may be entered using a user interface.

[0108] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 1029. Signals for controlling the process are output at analog and digital output connections of the deposition apparatus 1000.

[0109] The system software may be designed or configured in many different ways. For example, various chamber component subroutines or control objects may be written to control the operation of the chamber components necessary to carry out a deposition process according to the disclosed embodiments. Examples of programs or program sections for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0110] In some embodiments, the controller 1029 is part of a system that may be part of the examples described above. Such systems may include processing tools, chambers, processing platforms, and / or semiconductor processing equipment with specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics to control pre-, during, and post-processing operations of the semiconductor wafer or substrate. These electronics may be referred to as a "controller" that may control various components or sub-components of the system. Depending on the processing requirements and / or type of system, the controller 1029 may be programmed to control any process disclosed herein, including supply of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, settings of radio frequency (RF) generators in some systems, settings of RF matching circuits, frequency settings, flow settings, fluid supply settings, position operation settings, wafer loading and unloading from the tool and other transport tools and / or load locks connected or coupled to the specific system.

[0111] In general, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits may include chips in firmware format that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various personalizations (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. In some embodiments, the operational parameters may be part of a recipe defined by a process engineer to accomplish one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or one or more processing steps during the manufacture of a wafer die.

[0112] In some embodiments, the controller 1029 may be part of or coupled to a computer that is integrated or coupled with the system, or otherwise networked or combined with the system. For example, the controller 1029 may be in the "cloud" that allows remote access of wafer processing, or may be all or part of a fab host computer system. The computer may allow remote access to the system to monitor the progress of a manufacturing operation, to study the history of past manufacturing operations, to study trends or performance metrics from multiple manufacturing operations, and to modify parameters of a current process, or to set up a processing step following a current process, or to start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network that may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings that are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool that the controller is configured to connect to or control. Thus, as discussed above, the controller may be distributed, for example, by including one or more separate controllers networked together and cooperating toward a common purpose, such as a process or control as described herein. An example of a controller distributed for such purposes would be one or more integrated circuits on the chamber that are located remotely (e.g., at the platform level or as part of a remote computer) and that cooperate to control a process in the chamber.

[0113] Without being limited thereto, example systems may include plasma etch chambers or modules, deposition chambers or modules, spin rinse chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, CVD chambers or modules, ALD chambers or modules, ALE chambers or modules, ion implantation chambers or modules, track chambers or modules, and other semiconductor processing systems that may be related to or used in the fabrication and / or manufacturing of semiconductor wafers.

[0114] As described above, depending on the processing steps being performed by the tool, the controller may be in communication with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools installed throughout the factory, a main computer, another controller, or tools used to transport materials to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0115] The controller 629 may include a variety of programs. A substrate positioning program may include program code for controlling chamber components used to load the substrate onto a pedestal or chuck and control the spacing between the substrate and other components of the chamber (such as gas inlets and / or targets). A process gas control program may include code for controlling gas composition, flow rates, pulse times, and, if necessary, code for flowing gases into the chamber prior to deposition to stabilize the pressure in the chamber. A pressure control program may include code for controlling the pressure in the chamber, for example, by adjusting a throttle valve in the exhaust system of the chamber. A heater control program may include code for controlling the current to a heating device used to heat the substrate. Alternatively, the heater control program may control the supply of a heat transfer gas (such as helium) to the wafer chuck.

[0116] Examples of chamber sensors that may be monitored during deposition include mass flow controllers, pressure sensors such as pressure gauges, and thermocouples mounted on the pedestal or chuck. Appropriately programmed feedback control algorithms may be used with data from these sensors to maintain desired process conditions.

[0117] The foregoing describes the implementation of the disclosed embodiments in single or multi-chamber semiconductor processing tools. The apparatus and processes described herein may be used in conjunction with lithographic patterning tools or processes for, for example, the fabrication or manufacture of semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, but not necessarily, such tools / processes will be used or performed together in a common fabrication facility. Lithographic patterning of films typically involves some or all of the following steps, with each step being provided by a number of possible tools: (1) applying a photoresist to a workpiece (i.e., substrate) using a spin-on or spray-on tool; (2) curing the photoresist using a hotplate, furnace, or UV curing tool; (3) exposing the photoresist to visible, UV, or X-ray light using a tool such as a wafer stepper; (4) patterning the resist by developing the resist and selectively removing the resist using a tool such as a wet bench; (5) transferring the resist pattern to the underlying film or workpiece using a dry etching tool or a plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper. Conclusion

[0118] Although the above embodiments have been described in some detail for clarity of understanding, it will be apparent that certain changes and modifications may be made within the scope of the appended claims. It should be noted that there are many other ways of implementing the process, system, and apparatus of the present embodiments. Thus, the present embodiments should be considered as illustrative rather than restrictive, and are not limited to the details described herein.

Claims

1. 1. A method comprising: providing a substrate having one or more features, each of the one or more features having at least one opening and an interior region that is fluidly accessible through the at least one opening; depositing a first layer of molybdenum in the one or more features; non-conformally treating the first layer, the treatment being preferentially applied to portions of the first layer near the at least one opening of the one or more features relative to portions of the first layer deeper than the interior region of the feature; A method comprising:

2. 2. The method of claim 1 , The method, wherein non-conformally treating the first layer comprises non-conformally constraining the first layer.

3. 2. The method of claim 1 , The method, wherein non-conformally processing the first layer comprises non-conformally etching the first layer.

4. 4. The method of claim 2 or 3, comprising: The method, wherein the step of treating the first layer is performed during deposition of the first layer of molybdenum.

5. 5. The method of claim 4, exposing the one or more features to a molybdenum precursor under conditions such that a flux or concentration of the precursor is toward the at least one opening in the one or more features.

6. 6. The method of claim 5, The method according to claim 1, wherein the molybdenum precursor is a molybdenum oxyhalide.

7. 7. The method of claim 6, The method, wherein the molybdenum oxyhalide has a lower growth rate near the one or more openings of the one or more features than in the interior region due to an etching reaction.

8. 7. The method of claim 6, The method, wherein the molybdenum oxyhalide has a lower growth rate near the one or more openings of the one or more features than in the interior region due to an inhibition process.

9. 4. The method of claim 2 or 3, comprising: The method, wherein the step of treating the first layer is performed after the first layer of molybdenum is deposited.

10. 10. The method of claim 9, The method, wherein treating the first layer comprises exposing the first layer to an inhibiting chemical.

11. 11. The method of claim 10, The method, wherein the inhibitor chemical is a nitrogen-containing chemical.

12. 12. The method of claim 11, The method, wherein treating the first layer comprises exposing the first layer to a nitrogen-containing chemical followed by exposing the first layer to either or both of hydrogen gas and a molybdenum precursor.

13. 10. The method of claim 9, The method, wherein treating the first layer comprises exposing the first layer to an etching chemistry.

14. 14. The method of claim 13, The method, wherein the etching chemistry is a halogen-containing chemistry.

15. 15. The method of claim 14, The method, wherein treating the first layer includes exposing the first layer to a halogen-containing chemical and then purging a chamber containing the substrate.

16. A method according to any one of claims 1 to 9, comprising: The method, wherein treating the first layer comprises exposing the first layer to a nitrogen-containing compound.

17. A method according to any one of claims 1 to 9, comprising: The method, wherein treating the first layer comprises exposing the first layer to a halogen-containing compound.

18. A method according to any one of claims 1 to 9, comprising: The method, wherein treating the first layer comprises exposing the first layer to ammonia or nitrogen trifluoride.

19. A method according to any one of claims 1 to 18, comprising the steps of: The method, wherein the step of treating the first layer is a non-plasma thermal process.

20. A method according to any one of claims 1 to 18, comprising the steps of: The method, wherein the step of treating the first layer is a plasma process.

21. A method according to any one of claims 1 to 20, comprising: The step of depositing the first layer of molybdenum may include using H as a reducing agent for a molybdenum oxyhalide precursor or a molybdenum halide precursor. 2 The method includes an atomic layer deposition process using

22. The method according to any one of claims 1 to 21, further comprising: depositing a second layer of molybdenum after non-conformally treating the first layer.

23. 23. The method of claim 22, The step of depositing the second layer may include using H as a reducing agent for a molybdenum oxyhalide precursor or a molybdenum halide precursor. 2 The method includes an atomic layer deposition process using

24. A method according to any one of claims 1 to 23, comprising the steps of: The method, wherein the substrate comprises a 3D structure having a sidewall, and the one or more openings of the one or more features are openings in the sidewall.

25. A method according to any one of claims 1 to 23, comprising the steps of: The one or more features have a closed end.

26. 1. A method comprising: (a) depositing a conformal layer of Mo in a feature using a molybdenum (Mo) precursor at a first Mo precursor flow rate, Mo precursor partial pressure, and Mo precursor dose time; (b) increasing at least one of a Mo precursor flow rate, a Mo precursor partial pressure, and a Mo precursor dose time to increase the flux of the Mo precursor at the opening of the feature, thereby depositing a second Mo layer over the Mo conformal layer; A method comprising:

27. 27. The method of claim 26, The Mo precursor is molybdenum oxychloride.

28. An apparatus comprising: a processing chamber having one or more stations each configured to hold a substrate; Hydrogen (H 2 2.) one or more process gas inlets for connecting to a gas source, a molybdenum precursor gas source, an inert purge gas source, and a process gas source; A controller for controlling operations in the device, (a) introducing H into the processing chamber through the one or more process gas inlets to deposit a first layer of molybdenum on a substrate; 2 alternating pulses of the molybdenum precursor and the molybdenum precursor; (b) after (a), injecting a treatment gas to treat the first layer of molybdenum; (c) after (b), introducing H into the processing chamber through the one or more process gas inlets to deposit a first layer of molybdenum on a substrate. 2 a controller having machine readable instructions for alternating between pulses of the ionizing agent and a molybdenum precursor pulse; An apparatus comprising:

29. An apparatus comprising: a processing chamber having one or more stations each configured to hold a substrate; Hydrogen (H 2 2.) one or more process gas inlets for connecting to a gas source, a molybdenum precursor gas source, an inert purge gas source, and a process gas source; A controller for controlling an operation of the device, (a) introducing H into the process chamber through the one or more process gas inlets to deposit a first layer of molybdenum on a substrate; 2 and injecting a molybdenum precursor; (b) after (a), a controller comprising machine-readable instructions for modifying either or both of a flow rate and a dose time of the Mo precursor to deposit a first layer of molybdenum on the substrate; An apparatus comprising:

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