Molybedenum fill

Abstract

Embodiments of a method for filling a feature with molybdenum (Mo) include depositing a first layer of Mo in the feature, which includes an opening and an interior, and processing the first layer non-conformally, such that the region near the opening is preferentially processed compared to the interior region. In some embodiments, a second Mo layer is deposited on the processed first layer. Embodiments of a method for filling a feature with Mo include controlling the Mo precursor flux to switch between conformal and non-conformal filling.

Description

[Technical Field]

[0001] This invention relates to molybdenum filling. [Previous Technology]

[0002] Material deposition (including tungsten-containing materials) is an essential part of many semiconductor manufacturing processes. These materials can be used for horizontal interconnects, through-holes between adjacent metal layers, and contacts between metal layers and devices. In an example of deposition, a tungsten layer can be deposited on a titanium nitride (TiN) barrier layer using a chemical vapor deposition (CVD) process with WF6 to form a TiN / W bilayer. However, with device miniaturization and the adoption of more complex patterning schemes in the industry, the deposition of thin tungsten films has become a challenge. The continuous reduction in feature size and film thickness presents many challenges to TiN / W film stacks. These include the higher resistivity of thinner films and the degradation of TiN barrier properties. Deposition in complex high aspect ratio structures (such as 3D NAND structures) is particularly challenging.

[0003] The background provided herein is for the purpose of outlining the context of the invention. The inventors’ work (within the scope described in the preceding paragraphs) and descriptions that may not have been otherwise considered prior art at the time of application are not expressly or impliedly acknowledged as prior art to this invention. [Summary of the Invention]

[0004] One aspect of the present invention relates to a method comprising providing a substrate including one or more features, each of the one or more features having at least one opening and an interior region through which fluid can flow; depositing a first layer of molybdenum on the one or more features; and nonconformally processing the first layer such that the processing is preferentially performed on a portion of the first layer near the at least one opening of the one or more features, relative to a portion of the first layer located further away in the interior region of the features.

[0005] In some embodiments, nonconformally processing the first layer includes nonconformally suppressing the first layer. In some embodiments, nonconformally processing the first layer includes nonconformally etching the first layer.

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

[0007] In some embodiments, the processing of the first layer is performed after the deposition of the first molybdenum layer.

[0008] In some embodiments, treating the first layer includes exposing it to an inhibitory chemical. In some embodiments, the inhibitory chemical is a nitrogen-containing chemical. In some of these embodiments, treating the first layer includes, after exposing it to the nitrogen-containing chemical, exposing it to one or more of hydrogen and a molybdenum precursor.

[0009] In some embodiments, processing the first layer includes exposing it to an etching chemical. In some of these embodiments, the etching chemical is a halogen-containing chemical. In some of these embodiments, processing the first layer includes rinsing a chamber housing the substrate after exposing it to the halogen-containing chemical.

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

[0011] In any of the above methods, the deposition of the first molybdenum layer includes an atomic layer deposition process, which uses H2 as a reducing agent for molybdenum oxyhalide or molybdenum halide precursors.

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

[0013] According to various embodiments, the substrate includes a 3-D structure with sidewalls, wherein the one or more openings of the one or more features are openings in the sidewalls. According to various embodiments, the one or more features have a closed end.

[0014] Another aspect of the present invention relates to a method comprising: using a molybdenum (Mo) precursor, depositing a conformal molybdenum (Mo) layer at a first molybdenum (Mo) precursor flow rate, a molybdenum (Mo) precursor partial pressure, and a molybdenum (Mo) precursor injection time; and increasing at least one of the molybdenum (Mo) precursor flow rate, the molybdenum (Mo) precursor partial pressure, and the molybdenum (Mo) precursor injection time to increase the molybdenum (Mo) precursor flux at the opening of the feature portion, thereby depositing a second molybdenum (Mo) layer on the conformal molybdenum (Mo) layer. In some of these embodiments, the molybdenum (Mo) precursor is molybdenum oxychloride.

[0015] Another aspect of the present invention 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 coupling to a hydrogen (H2) gas source, a molybdenum precursor gas source, an inert rinsing gas source, and a process gas source; and a controller for controlling operations in the apparatus, including machine-readable instructions for: (a) alternately introducing H2 and molybdenum precursor pulses into the process chamber through the one or more process gas inlets to deposit a first molybdenum layer on the substrate; (b) after (a), introducing a process gas to process the first molybdenum layer; and (c) after (b), alternately introducing H2 and molybdenum precursor pulses into the process chamber through the one or more process gas inlets to deposit a second molybdenum layer on the substrate.

[0016] Yet another aspect of the present invention 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 coupling to a hydrogen (H2) gas source, a molybdenum precursor gas source, an inert rinsing gas source and a process gas source; and a controller for controlling operations in the apparatus, including machine-readable instructions for: (a) introducing H2 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), changing one or more of the molybdenum (Mo) precursor flow rate or injection time to deposit a second molybdenum layer on the substrate.

[0017] These and other states are further described below with reference to the diagrams.

Implementation Method

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

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

[0033] This document provides a method for filling feature portions with molybdenum (Mo), which can be used in logic and memory applications. Figures 1A and 1B are schematic examples of material stacks (including Mo) according to various embodiments. Figures 1A and 1B illustrate the material sequence in a particular stack and can be used with any suitable architecture and application, as further described below with respect to Figures 2A-2J. In the example of Figure 1A, substrate 102 has a Mo layer 108 deposited thereon. Substrate 102 may be a silicon or other semiconductor wafer, such as a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, which includes a wafer having one or more layers of material (e.g., dielectric, conductive, or semiconducting material) deposited thereon. These methods can also be applied to form metallized stack structures on other substrates (e.g., glass, plastic, and the like).

[0034] In FIG. 1A, dielectric layer 104 is on substrate 102. Dielectric layer 104 may be deposited directly on the semiconductor (e.g., Si) surface of substrate 102, or may be any number of intermediate layers. Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, specifically including doped and undoped layers of SiO2 and Al2O3. Also, in FIG. 1A, diffusion barrier layer 106 is disposed between Mo layer 108 and dielectric layer 104. Examples of diffusion barrier layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten nitride (WN), and tungsten carbonitride (WCN). A further example of a diffusion barrier layer is a multi-component molybdenum-containing film, as further described below. Mo layer 108 is the main conductor of this structure. In some embodiments, Mo layer 108 may include multiple host layers deposited under different conditions. Mo layer 108 may or may not include a Mo nucleation layer. In addition, in some embodiments, the Mo layer 108 may be deposited on a growth initiation layer comprising another material, such as tungsten (W) or a W-containing growth initiation layer.

[0035] Figure 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 intermediate diffusion barrier layer. The Mo layer 108 is as described with respect to Figure 1A. By using Mo, which has a lower electron mean free path than W, as the dominant material, a thin film with lower resistivity can be obtained.

[0036] Although Figures 1A and 1B illustrate examples of metallization stacks, the methods and resulting stacks are not limited thereto. For example, in some embodiments, Mo may be deposited directly on Si or other semiconductor substrates with or without a starter layer. Figures 1A and 1B illustrate examples of material ordering in a particular stack and can be used with any suitable architecture 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 housed in a chamber). The substrate may be a silicon or other semiconductor wafer, such as a 200 mm, 300 mm, or 450 mm wafer, comprising a wafer having one or more layers of material (e.g., dielectric, conductive, or semiconductive material) deposited thereon. These methods are not limited to semiconductor substrates and can be performed on any feature filled with molybdenum.

[0038] The substrate may have features such as through-holes or contact holes, which may be characterized by one or more of narrow and / or recessed openings, narrowing within the feature, and high aspect ratios. The features may be formed in one or more of the aforementioned layers. For example, the features may be at least partially formed 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 higher. One example of a feature is a hole or through-hole in a layer on a semiconductor substrate or substrate.

[0039] Figure 2A illustrates a schematic example of a dynamic random access memory (DRAM) architecture, which includes Mo buried word lines (bWLs) 208 in a silicon substrate 202. The Mo bWLs are formed in trenches etched into the silicon substrate 202. A conformal barrier layer 206 and an insulating layer 204 disposed between the conformal barrier layer 206 and the silicon substrate 202 form the lining of the trenches. In the example of Figure 2, the insulating layer 204 may be a gate oxide layer formed of a high-k dielectric material (e.g., silicon oxide or silicon nitride). In some embodiments disclosed herein, the conformal barrier layer is TiN or a tungsten-containing layer, such as WN or WCN. In some embodiments, the TiN is used as the barrier layer, and a conformal tungsten-containing growth initiation layer may be present between the conformal barrier layer 206 and the Mo bWL 208. Alternatively, MobWL 208 can be deposited directly on TiN or other diffusion barrier layers. In some embodiments, neither or both of layers 204 and 206 are present.

[0040] The bWL structure shown in Figure 2A is an example of an architecture containing a Mo filler layer. During the fabrication of the bWL, Mo is deposited into the feature defined by the etched recess in the silicon substrate 202, and the etched recess is conformally lined with layers 206 and 204 (if present).

[0041] Figures 2B-2H are additional schematic examples of various structures in which Mo can be deposited according to the disclosed embodiments. Figure 2B shows an example cross-sectional view of a vertical feature 201 to be filled with Mo. This feature may include a feature hole 205 in the substrate 202. The hole 205 or other feature may have a size close to the opening, such as an opening diameter or linewidth between about 10 nm and 500 nm (e.g., between about 25 nm and about 300 nm). The feature hole 205 may be referred to as an unfilled feature or simply a feature. Feature 201 and any feature may be characterized in part by an axis 218 extending through the length of the feature, with vertically oriented features having a vertical axis and horizontally oriented features having a horizontal axis.

[0042] In some embodiments, the feature is a character line feature in a 3D NAND structure. For example, the substrate may include a character line structure having any number of character lines (e.g., 50 to 150) with a vertical channel at least 200 Å deep. Another example is a trench in a substrate or layer. The feature may have any depth. In many embodiments, the feature may have an underlayer, such as a barrier layer or an adhesive layer. Non-limiting examples of the underlayer include dielectric and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxide, metal nitride, metal carbide, and metal layers.

[0043] FIG2C shows an example of a feature 201 with a recessed profile. The recessed profile is a profile that narrows from the bottom, closed end, or interior of the feature toward the opening of the feature. According to various embodiments, the profile may gradually narrow and / or include a protrusion at the opening of the feature. FIG2C shows an example of the latter, in which a bottom layer 213 forms a substrate against the sidewall or inner surface of the feature hole 105. The bottom layer 213 may be, for example, a diffusion barrier layer, an adhesive layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of the bottom layer may include dielectric and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers. In certain embodiments, the bottom layer may be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the bottom layer is tungsten-free. In some embodiments, the bottom layer is molybdenum-free. The bottom layer 213 forms a protrusion 215, making the bottom layer 213 thicker near the opening of the feature portion 201 than inside the feature portion 201.

[0044] In some embodiments, a feature having one or more recesses may be filled within the feature. FIG2D shows a view example of a plurality of filled features having recesses. Each example (a), (b), and (c) in FIG2D includes a recess 209 at the midpoint within the feature. The recess 209 may, for example, be between about 15 nm and 20 nm wide. The recess can cause pinch-off during the deposition of tungsten or molybdenum in the feature using conventional techniques, and the deposited metal can prevent further deposition beyond the recess before a portion of the feature is filled, resulting in porosity in the feature. Example (b) further includes a substrate / barrier protrusion 215 at the feature opening. These protrusions may also be potential pinch-off points. Example (c) includes a recess 212 further away from the field region than the protrusion 215 in Example (b).

[0045] Horizontal features, for example, in a 3D memory structure, can also be filled. FIG2E shows an example of a horizontal feature 250 including a recess 251. For example, the horizontal feature 250 may be a word line in a 3D NAND (also known as a vertical NAND or VNAND) structure. In some embodiments, the recess may be due to the presence of pillars in the 3D NAND or other structures. FIG2F presents a cross-sectional side view of a 3-D NAND structure 210 (formed on a silicon substrate 202) having VNAND stacks (left 225 and right 226), a central vertical structure 230, and a plurality of stacked horizontal features 220 having openings 222 on the opposite sidewalls 240 of the central vertical structure 230. Note that Figure 2F shows two "stacks" of the illustrated 3-D NAND structure 210, which together form a "groove-like" central vertical structure 230. However, in some embodiments, there may be more than two "stacks" arranged sequentially and spatially parallel to each other, with the gap between each adjacent "stack" pair forming the central vertical structure 230, as clearly shown in Figure 2F. In this embodiment, the horizontal feature 220 is a 3-D memory character line feature that can flow into the central vertical structure 230 through the opening 222. Although not explicitly shown in the figure, the horizontal feature 220 present in both the 3-D NAND stacks 225 and 226 shown in Figure 2F (i.e., the left 3-D NAND stack 225 and the right 3-D NAND stack 226) can also enter from the other side of the stack (the leftmost and rightmost sides, respectively) through similar vertical structures formed by additional 3-D NAND stacks (at the leftmost and rightmost sides, but not shown). In other words, each 3-D NAND stack 225, 226 contains a stack of word line features, which can flow in from both sides of the 3-D NAND stack through the central vertical structure 230. In the specific example schematically shown in FIG2F, each 3-D NAND stack contains 6 pairs of stacked word lines, but in other embodiments, the 3-D NAND memory layout may contain any number of vertically stacked word line pairs.

[0046] The word line features in a 3-D NAND stack are typically formed by depositing alternating layers of silicon oxide and silicon nitride, followed by selectively removing the nitride layers and leaving a stack of oxide layers with gaps between them. These gaps are the word line features. Any number of word lines can be vertically stacked in such 3-D NAND structures, provided that there are available techniques for forming word lines and techniques for successfully achieving (substantially) non-porous filling of vertical features. Thus, for example, a VNAND stack may include horizontal word line features between 2 and 256, or between 8 and 128, or between 16 and 64, etc. (the listed ranges should be understood to include the endpoints).

[0047] FIG2G presents a cross-sectional top view of the same 3-D NAND structure 210 shown in the side view of FIG2F, the cross-section being obtained through a horizontal section 260, as shown by the horizontal dashed line in FIG2F. The cross-section of FIG2G shows several rows of pillars 255, which are shown in FIG2F as vertical traces from the substrate of the semiconductor substrate 202 to the top of the 3-D NAND stack 210. In some embodiments, these pillars 255 are formed of polysilicon and are structurally and functionally important to the 3-D NAND structure 210. In some embodiments, these polysilicon pillars may serve as gate electrodes for stacked memory cells (formed within the pillars). The top view of FIG2G shows that the pillars 255 form a recess in the opening 222 leading to the word line feature 220—that is, the fluid accessibility of the word line feature 220 (entering from the central vertical structure 230 through the opening 222, as shown by the arrow in FIG2G) is suppressed by the pillars 255. In some embodiments, the horizontal gap size between adjacent polycrystalline silicon pillars is between approximately 1 and 20 nm. Reduced fluid permeability increases the difficulty of uniformly filling the character line feature 120 with material. The structure of the character line feature 220 and the challenge of uniformly filling it with molybdenum material due to the presence of pillars 255 are further illustrated in Figures 2H, 2I, and 2J.

[0048] Figure 2H shows a vertical cross-section through a 3-D NAND structure similar to that shown in Figure 2F, but here focusing on a pair of character line features 220, and additionally schematically illustrating the filling process that results in the formation of pores in the filled character line features 220. Figure 2I also schematically illustrates the pores 275, but this figure shows them through a horizontal cross-section through the pillar 255, similar to the horizontal cross-section shown in Figure 2G. Figure 2J shows the accumulation of molybdenum material around the pillar 255 forming the shrinkage, which causes the opening 222 to be clamped, preventing the deposition of additional molybdenum material in the region of the pores 275. As can be clearly seen from Figures 2H and 2I, the non-porous molybdenum filling depends on a sufficient amount of deposited precursor migrating downwards through the vertical structure 230, through the opening 222, across the narrowed column 255, and into the farthest extent of the character line feature 220 before the molybdenum deposit around the column 255 creates the opening 222, clamping and preventing the precursor from migrating into the character line feature 220. Similarly, Figure 2J shows a single character line feature 220 as seen from the top cross-section and illustrates how the generally conformal deposition of molybdenum material partially blocks and / or narrows and / or shrinks the open path that would otherwise pass through the character line feature 220 due to the significant width of the column 255, thus clamping the interior of the character line feature 220. (It should be noted that the example in Figure 2J can be understood as a 2D rendering of the 3D feature of the column reduction shown in Figure 2I, thus showing the reduction as seen in a plan view rather than a cross-sectional view.)

[0049] Three-dimensional structures may require longer and / or more concentrated exposure to the precursor to allow the innermost and bottommost regions to be filled. Three-dimensional structures can be particularly challenging when using molybdenum halide and / or molybdenum oxyhalide precursors because they are easy to etch, and longer and more concentrated exposure results in more etching as part of the structure.

[0050] Examples of feature filling for horizontally oriented and vertically oriented features are described below. It should be noted that, in at least most examples, these examples apply to both horizontally oriented and vertically oriented features. Furthermore, it should be noted that, in the following description, the term "lateral" may be used to refer to a direction approximately orthogonal to the feature axis, and the term "vertical" refers to a direction approximately along the feature axis.

[0051] The distribution of material within a feature can be characterized by its stepped coverage. For descriptive purposes, "stepped coverage" is defined as the ratio of two thicknesses, i.e., the thickness of the material within the feature divided by the thickness of the material near the opening. For the purposes of this document, the term "inside the feature" refers to the middle portion of the feature located near the midpoint of the feature along the feature axis, for example, an area approximately 25% to 75% of the feature depth measured from the feature opening, or approximately 40% to 60% in some embodiments, or the end of the feature located approximately 75% to 95% of the feature axis measured from the opening. The terms "near the opening of the feature" or "near the opening of the feature" refer to the top of the feature, which is located within 25% (in some embodiments, within 10%) of the opening edge or other element representing the opening edge. The conformal film will have approximately 100% stepped coverage. A step coverage of over 100% can be achieved, for example, by filling the feature with more material in the middle or near the bottom of the feature than at the opening of the feature.

[0052] Figure 3 is a process diagram illustrating the operation of a molybdenum-filled structure according to various embodiments. First, in operation 302, a molybdenum (Mo) film is deposited in the structure. This operation may be referred to as deposition 1. In many embodiments, operation 302 is a generally conformal deposition, which forms a substrate on the exposed surface of the structure. For example, in a 3D NAND structure (e.g., shown in Figure 2F), the Mo film forms a substrate on the character line feature 220. According to various embodiments, the Mo film is deposited using an ALD process to achieve good conformality. Further description of the Mo ALD process is provided below. In some embodiments, after operation 302, the feature is not closed by Mo, but is left fully open to allow further reactive gases to enter the feature in subsequent deposition.

[0053] Next, in operation 304, the deposited film undergoes non-conformal processing. Non-conformal processing, as used herein, refers to processing performed preferentially at or near one or more openings of the feature portion, rather than inside the feature portion. For 3D NAND structures, this processing can be conformal in the vertical direction, such that the processing degree of the bottom character line feature portion is approximately the same as that of the top character line feature portion, while non-conformal processing means that the interior of the character line feature portion is not processed or is processed to a significantly smaller degree than the feature portion opening.

[0054] Nucleation inhibition inhibits subsequent molybdenum nucleation on the treated surface. This may involve one or more of the following: inhibiting film deposition, the reaction of the treated material with the Mo film to form a compound film (such as Mo2N), and the adsorption of the inhibiting material. During subsequent deposition operations, 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 on the treated surface. This may include reacting an etchant material with the molybdenum film to form gaseous byproducts, 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 non-plasma, it may be purely thermal or activated by some other energy source (e.g., UV).

[0055] Nitrogen acts as an inhibitor, while halogens (e.g., fluorine and chlorine) act as etchants. To perform a pure inhibition process, operation 304 may include exposing the Mo film to a nitrogen-containing chemical that does not contain halogens. To perform a pure etching process, operation 304 may include exposing the Mo film to a halogen-containing chemical that does not contain nitrogen. Other inhibitory chemicals (e.g., oxygen-containing chemicals) may be used in some embodiments. Exposing the film to both nitrogen-containing and halogen-containing chemicals (e.g., nitrogen trifluoride (NF3) or ammonia / fluorine (NH3 / F2)) can simultaneously inhibit and etch.

[0056] According to various embodiments, operation 302 can be performed in the same processing chamber or different processing chambers. If performed in the same chamber, it can be performed in a single-station or multi-station chamber. In some embodiments, in a multi-station chamber, operation 302 can be performed in a first station and operation 304 can be performed in a second station. As discussed further below, operation 304 can be a continuous flow or pulsed process. In the latter example, different gases can be pulsed sequentially to modulate the process.

[0057] Following operation 304, a second deposition is performed in operation 306. This second deposition can be performed via an ALD or CVD process. The ALD process is further described below with reference to FIG8 and typically involves alternating pulses of reactants for surface-mediated reactions. In the CVD method, reactants are typically introduced and present in the gas phase within the reaction chamber. CVD can involve gas-phase reactions. To deposit into a 3D NAND structure, an ALD process can be used to achieve good step coverage throughout the structure. The gas can more easily reach the interior of the feature due to this process. After the etching process, the film deposited near the feature entrance is removed, thereby providing more space for the gas to reach the interior of the feature and preventing trapping. In some embodiments, sufficient Mo film may be removed to expose all or part of the underlying surface, thereby increasing the nucleation delay in these areas. After the suppression process, the nucleation delay is increased, thereby achieving a fill process from the inside out. In some embodiments, operation 306 (which may be referred to as the deposition 2 process) completes the filling of the structure. In other embodiments, an additional processing / deposition operation may be performed. To adjust for lateral nonconformity in the character line, the pressure and processing gas flow rate can be controlled. Higher chamber pressure and lower processing gas flow rate (and / or concentration) promote processing at the opening of the character line feature, which is more extensive than processing inside the character line feature. Therefore, in some embodiments, the chamber pressure ranges from 3 Torr to 40 Torr.

[0058] To achieve lateral non-conformal but top-to-bottom uniformity, a loading container can be used to deliver the gas. These are described below with respect to FIG. 7 and may be particularly useful for deep structures (e.g., 7-10 micrometers deep). In some embodiments, deposition and non-conformal processing can be performed simultaneously. For example, operations 302 and 304 in FIG. 3 can be performed simultaneously. According to various embodiments, subsequent deposition (e.g., deposition 2) can be performed, or operations 302 and 304 may be sufficient to fill the feature. As mentioned above, molybdenum halide and molybdenum oxyhalide can be used as etchant gases. In some embodiments, these can be used as deposition and etchant gases. By appropriately controlling the concentration of the deposition reactants within the feature, the amount of deposition and etching in the feature can be controlled at various stages. In a particular example, molybdenum oxychloride (MoOxCly, where x and y are numbers greater than 0 that form a stable compound) can be used as the Mo deposition and etchant gas, which has net deposition inside the feature and lower deposition or net etching at the feature opening. As further described below with respect to Figure 6D, the overall growth rate is sensitive to the precursor flux or concentration at the surface. In some embodiments, a higher MoOxCly flux can result in more etching. Furthermore, at high MoOxCly fluxes, the precursor concentration inside the feature is lower than near the opening or on the field region, thereby allowing bottom-up growth. Precursor injection time, precursor flow rate, chamber pressure, and precursor partial pressure can be used to modulate the precursor flux.

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

[0060] Figure 4 illustrates an example of performing a process for a molybdenum-filled 3D NAND structure. Figure 4 shows a cross-sectional view of a single word line of the 3D NAND structure. (As shown in the example of Figure 2J, the word line feature in Figure 4 shows a cylindrical contraction that can be seen in a plan view rather than a cross-sectional view, to illustrate the contraction.) At 470, the word line feature is shown after deposition 1. A bottom layer 406 is shown; this can be, for example, a barrier layer. A conformal Mo film 405 forms a substrate on the feature surface. In some embodiments, the conformal Mo film 405 is deposited directly on a dielectric surface, such as an alumina or silicon oxide surface. The Mo layer 405 can be a nucleation layer, a nucleation and host layer, or a host layer. Next, at 471, the feature is exposed to suppressing chemicals to suppress a site 465. In this example, the site 465 through the cylindrical contraction 451 is suppressed, while the internal surface at 452 is not suppressed. Suppression can include, for example, exposure to NH3 gas, or exposure to distal or direct (in-situ) plasma generated by gases (e.g., N2, H2, forming gases, NH3, O2, CH4, etc.). Next, a process is performed to selectively deposit molybdenum according to the suppression profile: the substrate Mo 408 is preferentially deposited on the unsuppressed areas of the Mo layer 405, thereby filling areas difficult to fill behind the shrinkage at 472. In this example, substrate deposition continues, filling the remaining areas of the feature with substrate Mo 408 at 473.

[0061] In some embodiments, the sequences shown in 471 and 472 can be performed in the operations discussed above by using a Mo precursor (which can act as an inhibitor at the feature opening during deposition).

[0062] Figure 5 illustrates another example of performing a process for a molybdenum-filled 3D NAND structure. In the example of Figure 5, a bottom layer 506 is shown; this can be, for example, a barrier layer. A conformal Mo film 505 forms a substrate on the feature surface. In some embodiments, the conformal Mo film 505 is deposited directly on a dielectric surface, such as an alumina or silicon oxide surface. The Mo layer 505 can be a nucleation layer, a nucleation and host layer, or a host layer. Following this, a non-conformal etching process (with high selectivity to protect the bottom layer 506, if present) is performed at 571. For example, a non-conformal etching process with high Mo:TiN selectivity can be performed on a TiN bottom layer. The result of the non-conformal etching is that the conformal Mo layer 505 remains intact within the feature interior 552, while it is thinned or completely removed at the feature opening 522. Next, at 572, a host Mo 508 is deposited on the remaining portion of the Mo layer 405, filling areas that are difficult to fill behind the shrinkage. In this example, the body deposition continues, filling the remaining portion of the feature with the body Mo 508 at 573. In some embodiments, the deposition-etch-deposition operation may be repeated to fill the feature. According to various embodiments, each subsequent deposition operation may or may not include the deposition of a nucleation layer. In some embodiments, the process may also include a suppression effect.

[0063] In some embodiments, the sequence shown in 571 and 572 can be performed in the operation discussed above by using a Mo precursor (which can act as an etchant at the feature opening during deposition).

[0064] In some embodiments, in the examples of FIG4 and FIG5, deposition 1 and deposition 2 are respectively used to deposit the main Mo layer, deposition 1 is used to deposit the conformal layer, and deposition 2 is used to fill the feature portion.

[0065] In some embodiments, the conformal Mo layer may be characterized as having low resistivity, and in some embodiments as having low stress and / or low fluorine. Because the character line features are not filled (other than the nucleation layer, if deposited), a relatively fast deposition technique can be used. In some embodiments, this includes alternating pulses of a molybdenum-containing precursor and hydrogen (H2) or other reducing agents to deposit a first tungsten layer in the ALD process. Rinsing operations may be spaced out by the pulses. Relatively short pulse times can be used for deposition to increase yield.

[0066] A second set of conditions may be used to deposit a second host layer. Like the first host layer, the second host layer may be a low resistivity layer, and in some embodiments may be a low-stress and / or low-fluorine layer. In some embodiments, operation 306 includes an increased pulse time and an increased rinse time relative to operation 302. In a particular embodiment, the pulse time containing the Mo precursor may be increased. Increasing the pulse and / or rinse time may promote the diffusion of reactants into the word lines. In some embodiments, the temperature may also be varied from operation 302 to operation 306; for example, a higher temperature may be used to accelerate the reaction time. In some embodiments, a lower temperature may be used to allow reactants to diffuse into the word line features before the reaction. In some embodiments, the second set of conditions may include a variation in flow rate. For example, the flow rate of the molybdenum-containing precursor and / or reducing agent may be increased.

[0067] A third host Mo layer can be deposited under different conditions. This layer can be characterized as a capping layer, which is removed in subsequent steps and can be deposited on sidewalls, such as sidewall 240 in the 3D NAND structure of Figure 2F. This layer can be characterized as having low roughness. Higher resistivity and / or fluorine concentration are permissible when removing molybdenum. The third set of conditions may include any of the following: faster timing (if ALD is used with a shorter pulse time than operation 405), use of CVD instead of ALD, and introduction of nitrogen (N2) during or between the inflow of one or more reactant gases.

[0068] Figure 6A is a process diagram illustrating the operation of processing a Mo film according to various embodiments. First, in operation 602, the surface is exposed to a halogen- and / or nitrogen-containing chemical substance. In operation 602, nitrogen is the inhibitory chemical substance; other inhibitory chemicals may be used in addition to nitrogen or suitably replaced by them. Fluorine- and chlorine-containing chemicals are used for etching. Operation 602 can be a continuous flow or pulsed operation, and can be a plasma or thermal non-plasma operation. Other activation energies may also be applied.

[0069] Exemplary nitrogen-containing gases used for suppression 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 flow into the chamber through a non-plasma thermal process, or it may be used to generate plasma in a remote or in-situ plasma generator. In some embodiments, a smaller amount of reactive gas (e.g., N2) may require plasma activation for effective suppression.

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

[0071] Next, in operation 604, a non-halogen gas can be used for rinsing. An inert gas, such as Ar or He, can be used. N2 can also be used. This rinsing is a non-plasma process that removes chlorine or fluorine substances from the surface. In some embodiments (e.g., in operation 602, the substrate is not exposed to chlorine or fluorine substances), operation 604 can be omitted.

[0072] Next, in operation 606, the surface may be exposed to a surface topography treatment gas. It has been found that suppression treatment results in a "rough" surface, which adversely affects the quality of the film deposited in deposition 2. The surface topography treatment gas may be a molybdenum precursor, a reducing agent (such as 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 in a multi-cycle pulse sequence. In alternative embodiments, operation 602 may be performed as multiple pulse cycles, while one or both of operations 604 and 606 are performed only when multiple cycles are completed. The order of operations 604 and 606 may be reversed in some embodiments. In some embodiments, molybdenum feature filling may be performed by controlling the precursor flux to control the step coverage of the resulting filling. Figure 6B shows a schematic example of a structure including a narrower and denser feature 610 and a wider and less dense feature 620, and how the step coverage of the Mo film 635 can be modified by appropriately controlling the Mo precursor flux. (Since flux is the flow rate per unit area, the flux can be increased or decreased by increasing or decreasing the flow rate into the chamber). At relatively low precursor flux, the step coverage is low, and more Mo is deposited near the top of the feature and on the field region 630 compared to the interior of the feature at 640.

[0074] As the precursor flux increases, the deposition becomes conformal, with approximately the same amount of Mo deposited conformally throughout the feature. The increased step coverage observed with increasing precursor flux is likely due to a shift from mass transfer-restricted growth to surface reaction-restricted growth.

[0075] At even higher precursor fluxes, growth becomes superconducting in the narrower and denser feature portions 610. As can be seen in the wider and less dense feature portions 620, bottom-up growth is observed, which produces a Mo film 635 at the bottom of the feature portion 620, but there is no significant deposition on the sidewalls of these feature portions.

[0076] In some embodiments, the precursor flux can be varied during Mo feature filling. For example, in the first stage of Mo filling, conformal growth conditions can be used, and growth in the field region can be suppressed. In subsequent stages, the precursor flux is increased, and superconformal and bottom-up growth is employed. Multi-step processes can be advantageously used to fill features of varying sizes. FIG6C is a process diagram illustrating the operation of a molybdenum-filled structure according to various embodiments. In the process of FIG6C, a conformal layer of Mo is deposited in the feature (652). CVD or ALD can be used. Then, in operation 654, the precursor flux is increased to transition to bottom-up filling. To increase the precursor flux, one or more of the following can be increased: Mo precursor partial pressure, Mo precursor flow rate, and Mo precursor injection time. Filling can be completed in operation 656. In some embodiments, operation 656 is a continuation of the conditions in operation 654. In other embodiments, the precursor flux can be reduced once the feature is filled to a certain point.

[0077] The Mo growth rate is sensitive to the precursor flux and concentration at the surface. In some embodiments, bottom-up growth is observed under high precursor flux conditions, where the precursor concentration deeper inside the feature is lower than that in the field region and near the top of the feature. This is because the higher precursor flux is more inclined towards etching than deposition, resulting in a lower growth rate. Chlorine-containing Mo precursors, for example, can lead to deposition and etching reactions: MoOxCly + H2 → Mo(s) + HCl + H2O (Mo bulk deposition, through low chloride) Mo + Cl2 → MoCly (Mo etching) Mo + MoCly → MozCly (Mo etching) If an underlayer, such as a W underlayer, is present, it can be etched under certain conditions: W + Cl2 → WCly (W etching) W + WCly → WzCly (W etching)

[0078] The reactions given above are examples of reactions that may occur under high Mo precursor conditions. Figure 6D is a graph showing the change in deposited molybdenum thickness with the flow rate of the molybdenum precursor. Figure 6D shows how net Mo deposition decreases under high precursor flux conditions using MoOCl4. (The data in Figure 6D are from CVD deposition of Mo; however, the same trend was observed using ALD. The difference between lower and higher ambient temperatures is 10 °C.) Three deposition states are shown: poor step coverage, conformal growth, and bottom-up growth. As can be seen from Figure 6D, net deposition decreases under high precursor flow rates. This may result in bottom-up filling, where the precursor concentration is higher at the top of the feature (resulting in a lower deposition rate) and lower inside the feature (resulting in a higher deposition rate). As mentioned above, in the case of laterally oriented features as shown in Figures 4 and 5, bottom-up filling (i.e., non-conformal filling) is filling from the inside out, and the feature is filled from the inside out.

[0079] These methods can be implemented using multiple loading containers. Figure 7 schematically illustrates an exemplary apparatus in which three gas sources (process gas 1, process gas 2, and flushing gas) are connected to loading containers. In some embodiments, one or more gas sources may be connected to multiple loading containers. The apparatus includes a gas manifold system that provides line loading to a plurality of gas distribution lines. The manifold provides process gas and flushing gas to the deposition chamber through valved loading containers. A plurality of valves are opened or closed to provide line loading, i.e., to pressurize the distribution lines.

[0080] Using a loading container, the processing gas can be delivered to the bottom of a high aspect ratio structure, for example, to the bottom word line of a 3D NAND structure. The pressurized gas flow passes through a spray head and reaches the wafer or other workpiece to be processed.

[0081] Examples of processing sequences include: Example 1: One or more (NF3 + Ar / rinse / H2 + Ar) cycles, where + indicates simultaneous gas inflow into the chamber and " / " indicates time intervals. Example 2: One or more (NH3 + Ar / H2 + Ar) cycles. Example 3: One or more (NH3 + Ar / Mo precursor + H2 + Ar) cycles. Example 4: One or more (NH3 + Ar / Mo precursor + Ar) cycles for Mo deposition.

[0082] To deposit molybdenum using the above method, molybdenum-containing precursors can be used, including molybdenum hexafluoride (MoF6), molybdenum pentachloride (MoCl5), molybdenum dichlorodioxide (MoO2Cl2), molybdenum tetrachlorodioxide (MoOCl4), and molybdenum hexacarbonyl (Mo(CO)6). The Mo-containing precursor can be a halide precursor, including MoF6 and MoCl5, as well as mixed halide precursors having two or more halogens capable of forming stable molecules. One example of a mixed halide precursor is MoClxBry, where x and y are any numbers greater than 0 capable of forming stable molecules. Organometallic precursors include Mo(X)m(L)n precursors, wherein 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, wherein m is selected from 1-4 and n is selected from 1-3, as disclosed in U.S. Provisional Patent Application No. 62 / 816,648. Organometallic precursors, such as molybdenum silylcyclopentadienyl and molybdenum silylallyl complexes, can also be used. Mo film deposition.

[0083] Figure 8 illustrates an example of an ALD method for forming a Mo film. The method according to Figure 8 can be used, for example, in one or both of operations 302 and 306 of Figure 3 and any operation of Figure 6C. First, in operation 805, the Mo precursor is pulsed. After the pulsed Mo precursor, an optional rinse 815 may be performed. Any unadsorbed precursor in the chamber may be rinsed using argon or any inert gas. The substrate is exposed to a co-reactant 825, which may be a reducing agent to reduce the Mo precursor, or other co-reactants 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). For plasma-based processes, distal or in-situ plasma generated from H2 may be used. An optional rinse may be performed at 835, followed by repeating operations 805-835 until the film is fully grown. This can be a conformal film lining the feature, such as a conformal Mo film 405 or 505, or a body layer filling all or some of the feature, such as a body Mo 408 or 508.

[0084] In some embodiments, operation 302 in the figure includes the deposition of a Mo nucleation layer, either as a conformal layer or as part of a conformal layer on which the host Mo is deposited.

[0085] In some embodiments, one or more of a boron-containing reducing agent (e.g., B₂H₆) or a silicon-containing reducing agent (e.g., SiH₄) are used as co-reactants to deposit the Mo nucleation layer. For example, one or more S / Mo cycles (where S / Mo refers to a silane pulse followed by a Mo-containing precursor pulse) may be used to deposit the Mo nucleation layer on which the host Mo layer is deposited. In another example, one or more B / Mo cycles (where B / Mo refers to a diborane pulse followed by a Mo-containing precursor pulse) may be used to deposit the Mo nucleation layer on which the host Mo layer is deposited. Both B / Mo and S / Mo cycles can be used to deposit the Mo nucleation layer, for example, x(B / Mo) + y(S / Mo), where x and y are integers. Examples of B and S-containing reducing agents are given below. In some embodiments, the Mo-containing precursor may be an oxygen-free precursor, such as MoF₆ or MoCl₅, for depositing the Mo nucleation layer. Oxygen in the oxygen-containing precursor can react with silicon- or boron-containing reducing agents to form MoSixOy or MoBxOy, which are impure, high-resistivity films. The oxygen-containing precursor can be used with minimal oxygen doping. In some embodiments, H2 can be used as the reducing gas to replace the boron- or silicon-containing reducing gas. Exemplary thicknesses for the deposition of the Mo nucleation layer range from 5 Å to 30 Å. Films at the lower end of this range may be discontinuous; however, this thickness may be sufficient as long as it helps to initiate continuous bulk Mo growth. In some embodiments, the reducing agent pulse can be performed at a lower substrate temperature than the Mo precursor pulse. For example, B2H6 or SiH4 (or other boron- or silicon-containing reducing agents) pulses can be performed at temperatures below 300 °C, while Mo pulses can be performed at temperatures above 300 °C.

[0086] Conformal deposition can also be performed directly on surfaces such as dielectrics and TiN surfaces using the process shown in FIG9. It can also be used on W-containing initial surfaces or Mo nucleation layers. 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 silane include SiH4 and Si2H6, while examples of borane include diborane (B2H6), and BnHn+4, BnHn+6, BnHn+8, BnHm, where n is an integer from 1 to 10, and m is an integer other than n. Other boron-containing compounds, such as alkylboranes, alkylboranes, amineboranes (CH3)2NB(CH2)2, and carboranes such as C2BnHn+2, may also be used. In some embodiments, the reducing agent layer may include silicon or silicon-containing materials, phosphorus or phosphorus-containing materials, germanium or germanium-containing materials, boron or boron-containing materials, and combinations thereof, capable of reducing tungsten precursors. Further exemplary reducing agent gases that can be used to form such layers include PH3, SiH2Cl2, and GeH4. According to numerous embodiments, hydrogen may or may not flow into the background. (Although hydrogen reduces tungsten precursors, it will not act as a reducing agent in a gas mixture containing sufficient amounts of stronger reducing agents (e.g., silane and diborane).)

[0087] In some embodiments, the reducing agent gas is a mixture containing a small amount of boron-containing gas (e.g., diborane) and another reducing agent. Adding a small amount of boron-containing gas can significantly affect the decomposition and adhesion coefficient of the other reducing agent. It should be noted that the substrate can be sequentially exposed to two reducing agents, such as silane and diborane. However, the inflow of the gas mixture can facilitate the addition of very small amounts of a few gases, such as silane and diborane in a ratio of at least 100:1. In some embodiments, a carrier gas can be inflowed. In some embodiments, a carrier gas, such as nitrogen (N2), argon (Ar), helium (He), or other inert gas, can be inflowed 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 can be adjusted to achieve a high deposition rate of the reducing agent layer while maintaining low resistivity. In some embodiments, the reducing agent layer may have, for example, between 5% and 80% B, or between 5% and 50% B, between 5% and 30% B, or between 5% and 20% B, with the balance consisting primarily of Si, and in some examples, of H. Hydrogen atoms are present, such as SiHx, BHy, GeHz, or mixtures thereof, wherein x, y, and z may independently be between 0 and numbers less than the stoichiometric equivalent of the corresponding reducing agent compound.

[0089] In some embodiments, the composition can be varied by the thickness of the reducing agent layer. For example, the reducing agent layer may be 20% B at the bottom and 0% B at the 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 forms a substrate for the feature.

[0090] The substrate temperature during operation 902 can be maintained at temperature T1 to maintain film conformability. If the temperature is too high, the film may not conform to the morphology of the underlying structure. In some embodiments, a step coverage greater than 90% or 95% is achieved. For silane, diborane, and silane / diborane mixtures, conformability is excellent at 300 °C and may deteriorate at 400 °C or higher. Therefore, in some embodiments, the temperature during operation 902 is up to 350 °C, or even up to 325 °C, 315 °C, or 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 can be performed for any suitable duration. In some examples, exemplary durations include between about 0.25 seconds and up to 30 seconds, between about 0.25 seconds and about 20 seconds, between about 0.25 seconds and up to 5 seconds, or between about 0.5 seconds and about 3 seconds.

[0092] In operation 904, the chamber may optionally be flushed to remove excess reducing agent that has not been adsorbed onto the substrate surface. Flushing may be performed by flowing in an inert gas at a fixed pressure, thus reducing the pressure in the chamber and repressurizing it before initiating another gas exposure. Exemplary inert gases include nitrogen (N2), argon (Ar), helium (He), and mixtures thereof. Flushing may be performed for a duration 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.

[0093] In operation 906, the substrate is exposed to a Mo-containing precursor at a substrate temperature T2. Examples of molybdenum-containing compounds are given above and include chlorides and oxychlorides. The use of an oxygen-containing precursor results in impurity doping and higher resistivity. However, if oxygen is incorporated, a very thin and potentially discontinuous reducing agent layer can be used to achieve an acceptable resistivity. In some embodiments, a carrier gas, such as nitrogen (N2), argon (Ar), helium (He), or other inert gas, may be introduced during operation 906. Examples of temperatures are 500 °C to 700 °C.

[0094] Operation 906 can be performed for any suitable duration. In some embodiments, it may include immersion of a molybdenum-containing precursor, and in some embodiments, it includes a sequence of molybdenum-containing precursor pulses. According to various embodiments, operation 906 may or may not be performed in the presence of H2. If H2 is used, in some embodiments, it and the Mo-containing precursor may be applied in an ALD-type manner. For example: repeated pulsed argon rinsing of the Mo-containing precursor with or without H2 in the background of H2 pulsed argon rinsing.

[0095] The substrate temperature T2 is sufficiently high to allow the Mo-containing precursor to react with the reducing agent layer to form elemental Mo. The entire reducing agent layer is converted into Mo. In some embodiments, the temperature is at least 450°C, and may be at least 550°C, to obtain a conversion rate equal to or close to 100%. The resulting feature is now lined with a conformal film of Mo. It 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. Generally, its thickness will be approximately the same as that of the reducing agent layer. In some embodiments, it may be up to 5% thicker than the reducing agent layer due to volume expansion during conversion.

[0096] Although the following description focuses on molybdenum feature filling, the present invention can also be implemented for feature filling with other materials. For example, the processing sequence described in FIG6 can be implemented using a feature filling process with tungsten, cobalt, or ruthenium-containing materials. Apparatus

[0097] Any suitable chamber may be used to implement the disclosed embodiments. Exemplary deposition apparatuses include a number of systems such as ALTUS® and ALTUS® Max (available from Lamb Research, Vermont, California), or any other commercially available processing systems.

[0098] In some embodiments, the first deposition may be performed at a first station, which is one of two, five, or even more deposition stations located within a single deposition chamber. Thus, for example, at the first station, individual gas supply systems (which create a localized atmosphere at the substrate surface) may be used to alternately pulse hydrogen (H2) and molybdenum dioxide dichloride (MoO2Cl2) onto the surface of the semiconductor substrate. Another station may be used for processing, while a third and / or fourth station is used for subsequent ALD body filling.

[0099] Figure 10 is a schematic diagram of a process system suitable for performing a deposition process according to an embodiment. System 1000 includes a transfer module 1003. The transfer module 1003 provides a clean and pressurized environment to minimize the risk of contamination when the substrate to be processed is moved between multiple reactor modules. Mounted on the transfer module 1003 is a multi-station reactor 1109, which is 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, which can perform operations sequentially according to the disclosed embodiments. For example, the multi-station reactor 1009 may be configured such that station 1011 uses a chlorine-containing molybdenum precursor and a boron- or silicon-containing reducing agent to perform molybdenum nucleation layer deposition, station 1013 uses H2 as a reducing agent to perform conformal ALD molybdenum body deposition, station 1015 performs processing operations, and station 1017 performs body ALD filling.

[0100] The station may include a heating base or substrate support, one or more gas inlets, or spray heads, or distribution plates. An example of a deposition station is shown in Figure 7, as described above.

[0101] Referring back to Figure 10, also mounted on the transfer module 1003 are one or more single-station or multi-station modules 1007 capable of performing plasma or chemical (non-plasma) pre-cleaning, other deposition operations, or etching operations. This module can also be used for various processes, such as preparing substrates for deposition processes. The system 1000 also includes one or more wafer source modules 1001, which serve as storage locations for wafers before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 1019 can first move the wafer from the source module 1001 to the loading chamber 1021. The wafer transfer device (generally a robotic arm unit) in the transfer module 1003 moves the wafer from the loading chamber 1021 to modules mounted on the transfer module 903 and moves it between these modules.

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

[0103] The controller 1029 controls all activities of the deposition equipment. The system controller 1029 executes system control software, including sets of instructions for controlling timing, gas mixing, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power level, substrate chuck or pedestal position, and other parameters for specific processes. Other computer programs stored on memory devices associated with the controller 1029 may be used in some embodiments.

[0104] Typically, a user interface associated with the controller 1029 will be stored. The user interface may include a display screen, a graphical software display of the device and / or process conditions, and a user input device, such as a pointing device, a keyboard, a touch screen, a microphone, etc.

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

[0106] The computer code controlling the germanium-containing reducing agent pulse, hydrogen flow rate, tungsten-containing precursor pulse, and other processes in the manufacturing program can be written in any known computer-readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. The compiled object code or document is executed by the processor to perform the tasks identified in the program. As indicated, the code can be hard-coded.

[0107] The controller parameters relate to process conditions, such as process gas composition and flow rate, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters are provided to the user in the form of a formula and can be input via a user interface.

[0108] Signals for monitoring the process can be provided via the analog and / or digital input connections of the system controller 1029. Signals for controlling the process can be output via the analog and digital output connections of the deposition equipment 1000.

[0109] The system software can be designed or configured in many different ways. For example, numerous chamber component subroutines or control targets can be written to control the operation of the chamber components that must perform the deposition process according to the disclosed embodiments. Examples of programs or program fragments used 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, which may be part of the examples described above. Such systems may include semiconductor processing equipment comprising a processing tool or multiple tools, a chamber or multiple chambers, a processing platform or multiple platforms, and / or specific processing components (wafer pedestals, airflow systems, etc.). Such systems may be combined with electronic equipment to control the operation of semiconductor wafers or substrates before, during, and after processing. Such electronic equipment may refer to a “controller” that controls various components or subcomponents of the system or multiple systems. The controller 1029, depending on processing requirements and / or system type, may be programmable to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (such as heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, and wafer transfer (entry and exit to tools and other transfer tools connected or coupled to a specific system, and / or loading chambers).

[0111] Broadly speaking, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software for receiving instructions, issuing instructions, controlling operations, initiating cleaning operations, initiating endpoint measurements, and the like. Integrated circuits may include: a chip in the form of firmware storing program instructions, a digital signal processor (DSP), a chip defined as an application-specific integrated circuit (ASIC), and / or one or more microprocessors, or a microcontroller that executes program instructions (e.g., software). Program instructions may be instructions transmitted to the controller in the form of various individual settings (or program files) that define operating parameters for implementing (on a semiconductor wafer, or for a semiconductor wafer, or for a system) a specific process. In some embodiments, operating parameters may be part of a formulation defined by a process engineer to achieve one or more processing steps during the manufacturing process of one or more of the following: layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer grains.

[0112] Controller 1029 may in some embodiments be part of, or coupled to, a computer that is integrated with the system, coupled to the system, connected to the system by means of other networks, or a combination thereof. For example, the controller 1029 may be in all, or part of a “cloud” or factory host computer system that allows remote access to wafer processing. The computer enables remote access to the system to monitor the current progress of a manufacturing operation, check the history of past manufacturing operations, check trends or performance measures from plural manufacturing operations to change the parameters of the current processing, set the processing steps after the current processing, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system via a network that may include a local area network or an Internet network. The remote computer may contain a user interface capable of parameter and / or setting input or programming, which may then be transmitted from the remote computer to the system. In some examples, the controller receives a data form instruction that specifies parameters for each processing step that is about to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be executed, and the type of tool to which the controller is engaged or controlled. Accordingly, as described above, the controller may be decentralized, such as by means of a controller containing one or more separate controllers connected together in a network manner and operating towards a common purpose (e.g., processes and control described herein). Distributed controllers for this purpose An example is one or more integrated circuits on the chamber communicating with one or more integrated circuits located at a remote end (e.g., at the level of the platform, or as part of a remote computer), which are combined to control the process on the chamber.

[0113] Exemplary systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, rotary cleaning chambers or modules, metal-coated chambers or modules, cleaning chambers or modules, beveled edge etching chambers or modules, physical gas phase deposition (PVD) chambers or modules, chemical gas phase deposition (C VD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, development (track) chambers or modules, and any other semiconductor processing system that may be associated with, or used, in the manufacture and / or processing of semiconductor wafers.

[0114] As described above, depending on the process steps or plural steps to be performed with recourse to the tool, the controller may communicate with one or more of the following in a semiconductor manufacturing plant: other tool circuits or modules, other tool elements, cluster tools, other tool interfaces, adjacent tools, adjacent tools, tools distributed throughout the plant, a master computer, another controller, or tools used in the material transport to and from the tool carrying port / container used in the material transport.

[0115] The controller 1029 may include various programs. The substrate positioning program may include program code for controlling chamber components used to load the substrate onto a pedestal or chuck, and controlling the spacing between the substrate and other components of the chamber (e.g., gas inlets and / or targets). The process gas control program may include code for controlling gas composition, flow rate, pulse duration, and optionally for allowing gas to flow into the chamber prior to deposition to stabilize the pressure within the chamber. The pressure control program may include code for controlling the pressure within the chamber by adjusting, for example, a throttle valve in the chamber's exhaust system. The heater control program may include code for controlling the current flowing to a heating unit used to heat the substrate. Alternatively, the heater control program may control the delivery of a heat-conducting gas (e.g., helium) to the wafer chuck.

[0116] Examples of chamber sensors that can be monitored during deposition include mass flow controllers, pressure sensors (e.g., pressure gauges), and thermocouples located on the base or suction cup. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain the desired process conditions.

[0117] The embodiments described above are implemented in single or multi-chamber semiconductor processing tools. The apparatus and processes described herein can be used in conjunction with, for example, photolithography tools or processes used in the manufacture or production of semiconductor devices, displays, LEDs, solar panels and the like. Typically, although not essential, such tools / processes will be used together or implemented in general manufacturing facilities. Photolithography patterning of films typically involves some or all of the following steps (performed using various possible tools): (1) applying photoresist onto the workpiece (i.e., substrate) using a spin coater or spray coater; (2) curing the photoresist using a hot plate, furnace, or UV curing tool; (3) exposing the photoresist to visible light, UV light, or X-ray light using a tool such as a wafer stepper; (4) developing the photoresist using a tool such as a wet bench to selectively remove the resist and thus pattern it; (5) transferring the resist pattern to the underlying film or workpiece using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist remover. Conclusion

[0118] While the foregoing embodiments have described some details for the purpose of clarity, 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 alternative methods for implementing the processes, systems, and devices of this embodiment. Accordingly, this embodiment should be considered illustrative rather than restrictive, and the embodiments are not limited to the details given herein. [Simplified Explanation of the Diagram]

[0018] Figures 1A and 1B are schematic examples of material stacks including molybdenum (Mo) according to various embodiments.

[0019] Figures 2A-2J are schematic examples of various structures in which molybdenum can be deposited according to the disclosed embodiments.

[0020] Figure 3 is a flowchart illustrating the operation of a molybdenum-filled structure according to various embodiments.

[0021] Figure 4 shows an example of performing a process to fill a 3D NAND structure with molybdenum.

[0022] Figure 5 shows another example of performing a process to fill a 3D NAND structure with molybdenum.

[0023] Figure 6A is a process diagram showing the operation of processing molybdenum film according to various embodiments.

[0024] Figure 6B shows a schematic example of a structure including narrower and denser features and wider and less dense features, and how the step coverage of the molybdenum film can be changed by controlling the flux of the molybdenum precursor.

[0025] Figure 6C is a process diagram illustrating the operation of a molybdenum-filled structure according to various embodiments.

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

[0027] Figure 7 is an example of an apparatus that can be used to implement the methods described herein.

[0028] Figure 8 is a process diagram showing the operation in the ALD method for forming a molybdenum film.

[0029] Figure 9 is a process diagram showing the operation of forming a molybdenum film using a reducing agent layer.

[0030] Figure 10 shows an example of a device that can be used to implement the methods described herein.

Claims

1. A method for molybdenum filling, the method comprising the following steps: providing a substrate, the substrate including a memory structure, the memory structure including multiple character line features and pillars, wherein each of the character line features has a first opening and a second opening, the first opening and the second opening being located at opposite ends of the character line features; forming a conformal molybdenum-containing layer in the character line features; non-conformally etching the conformal molybdenum-containing layer such that the etching at portions of the conformal molybdenum-containing layer near the first opening and the second opening is greater than the etching at portions of the conformal molybdenum-containing layer farther from the first opening and the second opening.

2. The molybdenum filling method as described in claim 1 further includes depositing at least one subsequent layer of molybdenum, wherein the conformal molybdenum-containing layer is deposited at a lower temperature compared to the subsequent layer of molybdenum.

3. The molybdenum-filled method as described in claim 1, wherein the step of non-conformal etching of the conformal molybdenum-containing layer includes exposing the conformal molybdenum-containing layer to a halogen-containing compound.

4. The molybdenum-filling method as described in claim 1, wherein the step of non-conformal etching of the conformal molybdenum-containing layer includes exposing the conformal molybdenum-containing layer to nitrogen trifluoride.

5. The molybdenum-filling method as described in claim 1, wherein the step of non-conformal etching of the conformal molybdenum-containing layer is a non-plasma thermal process.

6. The molybdenum-filling method as described in claim 1, wherein the step of forming the conformal molybdenum-containing layer includes an atomic layer deposition process in which H2 is used as a reducing agent for molybdenum oxyhalide or molybdenum halide precursors.

7. The molybdenum filling method as described in claim 2, wherein the step of depositing the molybdenum of the subsequent layer includes an atomic layer deposition process, which uses H2 as a reducing agent for molybdenum oxyhalide or molybdenum halide precursors.

8. The molybdenum filling method as described in claim 1, wherein the step of forming the conformal molybdenum-containing layer and the step of non-conformal etching the conformal molybdenum-containing layer are performed simultaneously.

9. The molybdenum-filling method as described in claim 1, wherein the conformal molybdenum-containing layer is deposited directly on a dielectric surface composed of alumina.

10. The molybdenum-filling method as claimed in claim 1, wherein the step of non-conformal etching of the conformal molybdenum-containing layer includes exposing the substrate to a halogen- or nitrogen-containing gas, exposing the substrate to a rinsing gas, and exposing the substrate to a surface treatment gas.

11. The molybdenum-filling method as described in claim 1, wherein the step of non-conformal etching of the conformal molybdenum-containing layer includes exposing the conformal molybdenum-containing layer to a pulsed or continuous flow of a molybdenum precursor.

12. The molybdenum-filling method as claimed in claim 1, wherein the substrate includes a 3-D structure having a plurality of sidewalls, wherein the character line features are horizontal features, the first opening and the second opening of one or more of the character line features are openings in the sidewalls, and wherein the step of non-conformally etching the conformal molybdenum-containing layer includes exposing one or more of the character line features to a process gas, wherein the process gas system is supplied from a loading container.

13. The molybdenum-filled method as described in claim 12, wherein non-conformal etching of the molybdenum-containing layer in each of the complex character line features results in lateral non-conformality of the etching and uniformity of the character line features from top to bottom.

14. A method for molybdenum filling, the method comprising the steps of: using a Mo precursor, depositing a conformal molybdenum (Mo) layer in a feature on a substrate at a Mo precursor flow rate, a Mo precursor partial pressure, and a Mo precursor implantation time; and increasing at least one of the Mo precursor flow rate, the Mo precursor partial pressure, and the Mo precursor implantation time to increase the Mo precursor flux at an opening in the feature, thereby depositing a second layer of Mo on the conformal molybdenum (Mo) layer.

15. The molybdenum filling method as described in claim 14, wherein the substrate includes a 3-D structure having a plurality of sidewalls, wherein the feature is a horizontal feature and the opening of the feature is an opening in the sidewall.

16. The method of molybdenum filling as described in claim 14, wherein the Mo precursor is delivered from a loading container.

17. The molybdenum filling method as described in claim 14, wherein the Mo precursor is molybdenum oxychloride.

18. The molybdenum-filling method as described in claim 14, wherein the Mo precursor is molybdenum chloride.

19. The molybdenum-filled method as described in claim 14, wherein the Mo precursor is MoF6.

20. A method of molybdenum filling, the method comprising the steps of: providing a substrate including one or more features, each of the one or more features having at least one opening and an internal region through which fluid can enter; depositing a first layer of molybdenum in the one or more features; and nonconformally processing the first layer such that the processing is preferentially performed on a portion of the first layer near the at least one opening of the feature relative to a portion of the first layer located further away in the internal region of the one or more features, wherein the processing includes exposing the first layer to molybdenum oxyhalide or molybdenum halide without causing the molybdenum oxyhalide or molybdenum halide to react with a reducing agent.

21. The molybdenum filling method as described in claim 20, wherein the process includes exposing the first layer to molybdenum oxychloride.

22. The molybdenum filling method as described in claim 20, wherein the process includes exposing the first layer to molybdenum halide.

23. A method of molybdenum filling, the method comprising the steps of: providing a substrate including one or more features, each of the one or more features having at least one opening and an internal region through which fluid can flow; depositing a first layer of molybdenum in each of the one or more features using a molybdenum precursor; and nonconformally processing the first layer such that the processing is preferentially performed on a portion of the first layer near the at least one opening of the feature relative to a portion of the first layer located further away from the internal region of the one or more features, and wherein the step of nonconformally processing the first layer includes nonconformally etching the first layer, wherein the step of nonconformally processing the first layer is performed during the deposition of molybdenum in the first layer, and wherein a portion of the molybdenum precursor reacts with a reducing agent to deposit molybdenum, and a remainder of the molybdenum precursor reacts with the deposited molybdenum to etch the molybdenum, whereby the molybdenum precursor acts as an etchant during the processing to etch the deposited molybdenum.

24. A molybdenum-filling apparatus, the apparatus comprising: A process chamber having one or more stations each configured to hold a substrate; One or more process gas inlets are used to couple to a hydrogen (H2) gas source, a molybdenum precursor gas source, an inert purging gas source, and a processing gas source. And a controller for controlling the operation of the device, the controller including machine-readable instructions for: (a) introducing H2 and a molybdenum precursor into the process chamber through one or more process gas inlets to deposit a first molybdenum layer on the substrate; (b) after (a), changing one or more of the flow rate or injection time of the molybdenum precursor to deposit a second molybdenum layer on the substrate.

25. The molybdenum-filled apparatus as described in claim 24, wherein the molybdenum precursor is molybdenum halide or molybdenum oxyhalide.

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