Molybdenum Halide in Memory Applications

Abstract

A process for filling features using a method is provided. The process includes deposition, etching, and cleaning operations using a molybdenum chloride (MoCl x ) compound. The MoCl x compound can be controlled to selectively deposit on metal nitride features as compared to a dielectric, form plugs and crystals on the dielectric material, and perform net etching of the material within the feature. Also provided is an in-situ cleaning process using the MoCl x compound to remove oxidation from the surface of the underlying layer prior to deposition. Subsequent depositions using the MoCl x precursor can deposit an initial layer and / or fill the feature.

Description

Technical Field

[0001] Incorporation by reference: As part of this application, a PCT application form is filed simultaneously with this specification. Each application specified in this simultaneously filed PCT application form and for which this application claims benefit or priority is hereby incorporated by reference in its entirety for all purposes into this specification.

Background Art

[0002] The deposition of materials containing tungsten-containing materials is an essential part of many semiconductor fabrication processes. These materials can be used as horizontal interconnects, vias between adjacent metal layers, contacts between metal layers and devices, and lines in memory devices. In one example of deposition, a tungsten (W) layer can be deposited on a titanium nitride (TiN) barrier layer by a CVD process using tungsten hexafluoride (WF 6 6) to form a TiN / W bilayer. However, as devices are scaled down and more complex patterning schemes are utilized in the industry, the deposition of tungsten thin films has become an issue. The continuous reduction in feature size and film thickness has brought various issues to the TiN / W film stack. These include high resistivity for thinner films and degradation of TiN barrier properties. Deposition in complex high aspect ratio structures such as 3D NAND structures is particularly difficult.

[0003] The description of the background provided herein is for the purpose of generally presenting the content of the present disclosure. Within the scope described in this background art section, research by the inventors named at the present time, as well as aspects of the description that cannot be separately regarded as prior art at the time of filing, are not admitted as prior art against the present disclosure, whether explicitly or implicitly.

Summary of the Invention

[0004] One aspect of the present disclosure relates to a method comprising: (a) providing a substrate comprising a feature having an opening and sidewalls, wherein a metal nitride layer lines the sidewalls of the feature; (b) using a molybdenum-containing halide compound to at least partially etch the metal nitride layer along the sidewalls of the feature, leaving a first portion of the metal nitride layer on the feature; and (c) selectively depositing molybdenum on the first portion of the metal nitride layer in the feature by reacting the molybdenum-containing halide compound with a first reactant after at least partially etching the metal nitride layer.

[0005] In some embodiments, (b) includes removing metal nitride from a portion of the sidewall to expose a portion of the sidewall of the feature.

[0006] In some embodiments, the feature has a feature bottom, and the method further includes (d) after (c), using a molybdenum-containing halide compound to at least partially etch the first portion of the metal nitride layer and the molybdenum, leaving a second portion of the metal nitride layer and the remaining molybdenum on the feature bottom.

[0007] In some embodiments, the method further includes (e) filling the feature with molybdenum.

[0008] In some embodiments, the molybdenum-containing halide compound is a molybdenum chloride compound.

[0009] In some embodiments, the molybdenum-containing halide compound is molybdenum pentachloride.

[0010] In some such embodiments, (e) includes reacting a second molybdenum-containing halide compound with a second reactant.

[0011] In some such embodiments, (e) includes reacting a molybdenum-containing oxyhalide precursor with a second reactant.

[0012] In some embodiments, the metal nitride layer conformally lines the features.

[0013] In some embodiments, (b) further includes reacting a molybdenum-containing halide compound with a first reactant to deposit molybdenum on the feature during etching.

[0014] In some embodiments, the reactant is a hydrogen-containing reactant.

[0015] In some embodiments, the first reactant is hydrogen (H 2 ).

[0016] In some embodiments, (b) is performed at a first substrate temperature and (c) is performed at a second substrate temperature, and the second temperature is higher than the first temperature.

[0017] One aspect of the present disclosure relates to a method including: (a) providing a substrate comprising a feature having an opening, a closed end, and a dielectric sidewall; (b) forming a molybdenum plug on the closed end of the feature by reacting a molybdenum-containing halide precursor with a reactant; and (c) selectively depositing molybdenum on the molybdenum plug by reacting the molybdenum-containing halide precursor with the reactant.

[0018] In some embodiments, the sidewall is inclined and intersects at the closed end of the feature.

[0019] In some embodiments, (d) further includes filling the feature with molybdenum after (c).

[0020] In some embodiments, (d) includes reacting a second molybdenum-containing halide compound with a second reactant.

[0021] In some embodiments, (d) involves reacting a molybdenum-containing oxyhalide compound with a second reactant.

[0022] In some embodiments, the molybdenum-containing halide compound is a molybdenum chloride compound.

[0023] In some embodiments, the molybdenum-containing halide compound is molybdenum pentachloride.

[0024] In some embodiments, the first reactant is a hydrogen-containing reactant.

[0025] In some embodiments, the first reactant is hydrogen (H 2 ).

[0026] In some embodiments, the substrate temperature is less than 450 °C in (b).

[0027] One aspect of the present disclosure relates to a method comprising: providing a substrate comprising a feature having a metal nitride plug; and selectively depositing molybdenum on the metal nitride plug in the feature by reacting a molybdenum-containing halide compound with a reactant.

[0028] In some embodiments, further comprising cleaning the feature using the molybdenum-containing halide compound between (a) and (b).

[0029] In some embodiments, (c) further comprises filling the feature with molybdenum after (b).

[0030] In some embodiments, the molybdenum-containing halide compound is a molybdenum chloride compound.

[0031] In some embodiments, the molybdenum-containing halide compound is molybdenum pentachloride.

[0032] In some embodiments, the first reactant is a hydrogen-containing reactant.

[0033] In some embodiments, the first reactant is hydrogen (H 2 ).

[0034] In some embodiments, filling the feature with molybdenum includes reacting a second molybdenum-containing halide precursor with a second reactant.

[0035] In some embodiments, filling the feature with molybdenum includes reacting a molybdenum-containing oxyhalide precursor with a reactant. BRIEF DESCRIPTION OF THE DRAWINGS

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[0045] In the following description, numerous specific details are set forth in order 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 have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. The disclosed embodiments are described in conjunction with specific embodiments, but it will be understood that the disclosed embodiments are not intended to be limiting.

[0046] This specification provides a method of filling features with molybdenum (referred to herein as Mo) that can be used for logic and memory applications. Molybdenum provides several advantages compared to other metals such as cobalt (Co), ruthenium (Ru), and tungsten (W): (i) deposition of barrierless and linerless molybdenum films is more feasible on oxides and nitrides compared to Co, Ru, and W, (ii) the resistivity scaling of molybdenum is superior to that of W, (iii) mixing of molybdenum with underlying Co is not expected compared to mixing of Ru with Co below 450 °C, and (iv) incorporation of molybdenum into current W schemes is relatively easy compared to Co and Ru.

[0047] Figures 1A and 1B are schematic examples of material stacks including molybdenum according to various embodiments. Figures 1A and 1B show the order of materials in an example of a particular stack and can be used in any suitable architecture and application, as further described below with respect to Figures 2A - 2J. Figure 1A shows a first material stack 111 featuring a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 may include a silicon or other semiconductor wafer, e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer having one or more layers of materials such as a dielectric, conductive, or semiconductive material deposited thereon. In some embodiments, the substrate 102 may be or include silicon germanium (SiGe). The method may also be applied to form a metallization stack structure on other substrates such as glass, plastic, etc.

[0048] Stack 111 has a dielectric layer 104 on substrate 102. The dielectric layer 104 may be deposited directly on the semiconductor surface (e.g., Si or SiGe surface) of substrate 102, or any number of intervening layers may be present. For example, substrate 102 can include any number of layers deposited in various arrangements on the semiconductor surface.

[0049] Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, and specific examples include doped or undoped layers of SiO 2 and Al 2 O 3 . Stack 111 has a layer 106 disposed between molybdenum layer 108 and dielectric layer 104. Layer 106 may be, for example, a diffusion barrier and / or an adhesion layer. A diffusion barrier is a layer that prevents the diffusion of species between layers. An adhesion layer is a layer that promotes the adhesion of a layer to a lower layer. Examples of diffusion barrier layers and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten (W), tungsten nitride (WN), and tungsten carbon nitride (WCN). Molybdenum layer 108 is a conductor of the structure. In some embodiments, molybdenum layer 108 can include a plurality of bulk layers deposited under different conditions. Molybdenum layer 108 may or may not include a molybdenum nucleation layer. In the illustrated example of FIG. 1A, molybdenum layer 108 is deposited directly on layer 106. In other embodiments (not shown), molybdenum layer 108 may be deposited on a separate layer such as a growth initiation layer that includes another material such as tungsten (W) or a W-containing growth initiation layer. The growth initiation layer can be used to facilitate the nucleation and growth of molybdenum layer 108.

[0050] FIG. 1B shows another example of stack 121. In this example, stack 121 includes substrate 102, dielectric layer 104, and molybdenum layer 108 is deposited directly on dielectric layer 104 without an intervening diffusion barrier or adhesion layer. Molybdenum layer 108 is as described with respect to FIG. 1A. By using molybdenum as the conductor, a thin film with a low resistivity can be obtained. Examples of thin films with low resistivity include films having a resistivity of less than 40 μΩ-cm at a thickness of 60 angstroms and less than 15 μΩ-cm at a thickness of 200 angstroms.

[0051] In some embodiments, a stack (not shown) can include a substrate, a conductive layer, and a molybdenum layer deposited on the conductive layer. As used herein, the conductive layer is a layer having a conductivity of at least 10 4 Ω -1 -cm -1 at room temperature. Examples include molybdenum on a metal layer (e.g., W). In these embodiments, there is no dielectric layer between the molybdenum layer and the conductive layer. Similarly, the stack can include molybdenum deposited directly on a metal compound layer. Examples include molybdenum on a metal nitride layer (e.g., TiN, WN, or MoN). In some further embodiments of the stack (not shown), the stack can include a substrate and a molybdenum layer deposited directly on the substrate, including on a semiconducting surface, a dielectric surface, or a conductive surface. FIGS. 1A and 1B show examples of the order of materials in a particular stack and can be used in any suitable architecture and application, as further described below with respect to FIGS. 2A - 2J.

[0052] The methods described herein are performed on a substrate that can be housed in a chamber. The substrate can be a silicon or other semiconductor wafer, including a wafer having one or more layers of materials such as a dielectric, conductive, or semiconducting material deposited thereon. The methods are not limited to semiconductor substrates and can be performed to fill any feature with molybdenum.

[0053] The substrate can have features such as vias or contact holes, which may be characterized by one or more narrow and / or concave corner openings, constrictions within the features, and high aspect ratios. The features can be formed in one or more of the stacks described above or in one or more of the layers within the stack. For example, the features may be formed at least partially in a dielectric layer. In some embodiments, the features can 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. An example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate.

[0054] FIG. 2A illustrates a schematic example of a DRAM architecture including a molybdenum (Mo) embedded word line (bWL) 208 in a silicon substrate 202. The molybdenum bWL is formed in a trench etched in the silicon substrate 202. The trench is lined with a conformal barrier layer 206 and an insulating layer 204. The conformal barrier layer 206 is disposed between the insulating layer 204 and the silicon substrate 202. In this example, 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 206 is a TiN or tungsten-containing layer. In embodiments where TiN is used as the conformal barrier layer, a conformal tungsten-containing growth initiation layer (not shown) may be present between the conformal barrier layer 206 and the molybdenum bWL 208. Alternatively, the molybdenum bWL 208 may be deposited directly on TiN or other diffusion barriers. In some embodiments, one or both of the layers 204 and 206 are absent.

[0055] The bWL structure shown in FIG. 2A is an example of an architecture including a molybdenum fill layer. During fabrication of the bWL, molybdenum is deposited into a feature that may be defined by an etched recess in the silicon substrate 202 that is conformally lined with layers 206 and 204 when layers 206 and 204 are present.

[0056] Figures 2B through 2H are additional schematic examples of various structures on which molybdenum can be deposited according to the disclosed embodiments. Figure 2B shows an example of a cross-section of a vertical feature 201 filled with Mo. The feature can include a feature hole 205 in a silicon substrate 202. The feature hole 205 may have an underlying layer 203 lining the sidewalls or interior of the feature hole 205 and may form an inner surface. The feature hole 205 or other features may have dimensions near the opening, such as 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 an unfilled feature, or may simply be referred to as a feature. The vertical feature 201 and any features can be partially characterized by an axis 218 extending along the length of the feature, with vertically oriented features having a vertical axis and horizontally oriented features having a horizontal axis. The underlying layer 213 can be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, combinations thereof, or any other applicable material. Non-limiting examples of underlying layers can include dielectric layers and conductive layers. Examples of dielectric materials include oxides such as silicon oxide (SiO 2 ) and aluminum oxide (Al 2 O 3 ), nitrides such as silicon nitride (SiN), carbides such as nitrogen-doped silicon carbide (NDC) and oxygen-doped silicon carbide (ODC), and low-k dielectrics such as carbon-doped SiO 2 . In certain embodiments, the underlying layer can be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the underlying layer is tungsten-free. In some embodiments, the underlying layer is molybdenum-free.

[0057] In some embodiments, the feature is a word line feature in a 3D NAND structure. For example, the substrate can include a word line structure having any number (e.g., 50 - 150) of word lines with vertical channels having a depth of at least 200 Å. Examples of word line features will be further described below. Another example of a feature is a trench in the substrate or layer. The feature can be of any depth. In various embodiments, the feature may have an underlying layer such as a barrier layer or an adhesion layer. Non - limiting examples of underlying layers include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, as well as metal layers.

[0058] FIG. 2C shows an example of a vertical feature 201 having a concave - corner profile. The concave - corner profile is a profile that narrows from the bottom, closed end, or interior of the feature to the feature opening. According to various embodiments, the profile can gradually narrow and / or can include an overhang at the feature opening. FIG. 2C shows an example of the latter, where the underlying layer 213 lines the sidewall or inner surface of the feature hole 105. Similar to FIG. 2B, the underlying layer 213 can be a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non - limiting examples of underlying layers can include dielectric layers and conductive layers. The underlying layer 213 forms an overhang 215 such that it is thicker near the opening of the vertical feature 201 than inside the vertical feature 201.

[0059] In some embodiments, features having one or more constrictions within the feature can be filled. FIG. 2D shows an example of a diagram of various filled features having constrictions. Each of examples (a), (b), and (c) of FIG. 2D includes a constriction 209 at an intermediate point within the feature. The width of the constriction 209 can be, for example, about 15 nm to 20 nm. The constriction can cause pinch-off when depositing molybdenum on the feature using conventional techniques, blocking further deposition of the deposited metal beyond the constriction before that portion of the feature is filled, resulting in voids in the feature. Example (b) further includes an overhang 215 (such as a liner / barrier overhang) at the feature opening. Such an overhang can also be a potential pinch-off point. Example (c) includes a constriction 212 that is further away from the field region than the overhang 215 of example (b).

[0060] Horizontal features, such as 3-D memory structures, can also be filled. FIG. 2E shows an example of a horizontal feature 250 that includes a constriction 251. For example, the horizontal feature 250 may be a word line in a 3-D NAND (also referred to as vertical NAND or VNAND) structure. In some embodiments, the constriction may be due to the presence of pillars in a 3D NAND or other structure. FIG. 2F shows a cross-sectional side view of a 3-D NAND structure 210 (formed on a silicon substrate 202) having a plurality of stacked horizontal word line features 220 with openings 222 on opposing sidewalls 240 of a central vertical structure 230 and 3-D NAND stacks (left 225 and right 226). Note that FIG. 2F shows two “stacks” of the represented 3-D NAND structure 210, which together form a “trench-like” central vertical structure 230. However, in certain embodiments, three or more “stacks” may be arranged in sequence and can extend spatially parallel to each other, and the gap between each adjacent pair of “stacks” forms a central vertical structure 230 as explicitly shown in FIG. 2F. In this embodiment, the horizontal word line feature 220 is a 3-D memory word line feature that is fluidly accessible from the central vertical structure 230 through the opening 222. Although not explicitly shown in the figure, the horizontal word line features 220 present in both 3-D NAND stacks 225 and 226 (i.e., the left 3-D NAND stack 225 and the right 3-D NAND stack 226) shown in FIG. 2F are also accessible from the other sides (left and right ends respectively) of the stack through similar vertical structures (left and right ends, not shown) formed by additional 3-D NAND stacks. Each 3-D NAND stack 225, 226 includes a stack of word line features that are fluidly accessible from both sides of the 3-D NAND stack through the central vertical structure 230. In the particular example schematically shown in FIG. 2F, each 3-D NAND stack includes six pairs of stacked word lines. However, the 3-D NAND memory layout may include any number of pairs of vertically stacked word lines.

[0061] Word line features in a 3-D NAND stack can be formed by depositing an alternating stack of silicon oxide layers and silicon nitride layers and then selectively removing the nitride layers to leave a stack of oxide layers having gaps therebetween. These gaps are the word line features. Any number of word lines can be vertically stacked in such a 3-D NAND structure as long as techniques for forming the word lines are available and techniques for successfully achieving (substantially) void-free filling of the vertical features are available. Thus, for example, a VNAND stack can include 2 to 512 horizontal word line features, 2 to 256 horizontal word line features, 8 to 128 horizontal word line features, or 16 to 64 horizontal word line features, etc. (the recited ranges are understood to include the recited endpoints).

[0062] FIG. 2G shows a cross-sectional view taken from above the same 3-D NAND structure 210 as shown in the side view of FIG. 2F, the cross-section being taken through the horizontal section 260 as indicated by the horizontal dashed line in FIG. 2F. The cross-section of FIG. 2G shows several columns of pillars 255 as shown in FIG. 1F extending vertically from the base of the substrate 202 to the top of the 3-D NAND structure 210. In some embodiments, the pillars 255 are formed from a polysilicon material and are structurally and functionally important to the 3-D NAND structure 210. In some embodiments, such polysilicon pillars can function as gate electrodes for the stacked memory cells formed within the pillars. The top view of FIG. 2G shows that the pillars 255 form a constriction within the opening 222 up to the word line feature 220. The fluid access to the word line feature 220 from the central vertical structure 230 through the opening 222 (as indicated by the arrow in FIG. 2G) is inhibited by the pillars 255. In some embodiments, the size of the horizontal gap between adjacent polysilicon pillars is from about 1 to 20 nm. This reduction in fluid access makes it difficult to uniformly fill the word line feature 120 with material. The structure of the word line feature 220 and the challenges of uniformly filling the word line feature 220 with a molybdenum material due to the presence of the pillars 255 are further shown in FIGS. 2H, 2I, and 2J.

[0063] FIG. 2H represents a vertical cut-away view of a 3-D NAND structure similar to that shown in FIG. 2F, but here focused on a single pair of word line features 220, and further schematically shows a fill process in which voids 275 are formed in the filled word line features 220. FIG. 1I also schematically shows void 175, but in this figure it is shown through a horizontal cut-away plane through pillar 155, similar to the horizontal cut-away plane represented in FIG. 2G. FIG. 2J shows the accumulation of molybdenum material around the constriction forming pillar 255, which causes pinch-off of the opening 222 and prevents additional molybdenum material from depositing in the region of void 275. As is apparent from FIGS. 2H and 2I, void-free molybdenum filling depends on a sufficient amount of deposition precursor passing through the central vertical structure 230, through the opening 222, through the constricted pillar 255, and to the outermost end of the word line feature 220 before molybdenum accumulates and deposits around pillar 255 to cause pinch-off of the opening 222 and prevent further migration of the precursor into the word line feature 220. Similarly, FIG. 2J represents a single word line feature 220 viewed in cross-section from above, and shows how the generally conformal deposition of molybdenum material begins to pinch-off the interior of the word line feature 220 due to the fact that a significant width of the pillar 255 acts to partially block and / or narrow and / or constrict what would otherwise be an opening path through the word line feature 220. (Note that the example of FIG. 2J can be understood as a 2D rendering of the 3-D features of the pillar constriction structure shown in FIG. 2I, and thus shows the constriction as viewed in a plan view rather than a cross-sectional view.)

[0064] To enable filling of the innermost and bottommost regions, the three-dimensional structure may require longer and / or more concentrated exposure to the precursor. The three-dimensional structure can be particularly difficult when using molybdenum halide and / or molybdenum oxyhalide precursors due to their etching tendencies, and longer and more concentrated exposure allows for more etching as part of the structure.

[0065] Figures 2K and 2L show an example of an asymmetric trench structure DRAM bWL. Some of the filling processes for DRAM bWL trenches can distort the trenches such that the final trench width and resistance Rs become significantly non-uniform. Figure 2K shows an unfilled feature 261 and a filled feature 265 that exhibits line curvature after filling. In this example, the feature is a narrow asymmetric trench structure DRAM bWL. As shown, a plurality of features 283 are illustrated on a substrate. These features 283 are spaced apart, and in some embodiments, adjacent features have a pitch of from about 20 nm to about 60 nm, or from about 20 nm to 40 nm. The pitch is defined as the distance between the central axis of one feature and the central axis of an adjacent feature. The unfilled feature 261 may generally be V-shaped with sloped sidewalls such that the width of the feature narrows from the top of the feature to the bottom of the feature, as shown by feature 283. The feature flares from a feature bottom 273b to a feature top 273a. Line curvature may be observed within the filled feature 265 after some filling operations. Without being bound by a particular theory, it is believed that the cohesive forces between the opposing surfaces of the trench draw the sides of the trench together, as illustrated by arrow 267. This phenomenon is shown in Figure 2L and can be characterized as "zipping up" the feature. As the feature 283 is filled, more force is exerted from the central axis 299 of the feature 283, resulting in line curvature. For example, molybdenum may be deposited on the sidewalls of the feature 283. Thus, molybdenum 284a and 284b deposited on the sidewalls of the feature 283 interact very closely when the molybdenum-molybdenum bond radius r is small, thereby creating an interatomic cohesive force between the smooth growth surfaces of the molybdenum that draws the sidewalls together, resulting in line curvature. A method of filling the feature to reduce line curvature is described below.

[0066] A method for filling features with molybdenum is provided below. The methods described herein include deposition, etching, and cleaning operations, which can be used to fill substrate features as described above. As described above, molybdenum offers several advantages compared to other metals such as cobalt (Co), ruthenium (Ru), and tungsten (W): (i) deposition of barrierless and linerless molybdenum films is more feasible on oxides and nitrides compared to Co, Ru, and W, (ii) the resistivity scaling of molybdenum is superior to that of W, (iii) mixing of molybdenum with Co in the underlying layer is not expected compared to mixing of Ru with Co below 450 °C, and (iv) incorporation of molybdenum into current W schemes is relatively easy compared to Co and Ru.

[0067] Examples of feature filling for horizontally and vertically oriented features are described below. Note that in at least most cases, the examples are applicable to both horizontally and vertically oriented features. Horizontally oriented features generally refer to features oriented such that the feature axis is parallel to the plane of the substrate surface. Vertically oriented features generally refer to features oriented such that the feature axis is perpendicular to the plane of the substrate surface.

[0068] The deposition of molybdenum described herein involves reacting a Mo-containing precursor, also referred to as a molybdenum precursor. In some embodiments, the molybdenum precursor is a molybdenum chloride precursor or MoCl x also referred to as a precursor, is a molybdenum chloride (MoCl x ) compound. The molybdenum chloride precursor is given by the formula MoCl x where x is 2, 3, 4, 5, or 6, and molybdenum dichloride (MoCl 2 ), molybdenum trichloride (MoCl 3 ), molybdenum tetrachloride (MoCl 4 ), molybdenum pentachloride (MoCl 5 ), and molybdenum hexachloride (MoCl 6) including. In some embodiments, MoCl 5 or MoCl 6 is used. In this description, mainly MoCl x precursor is referred to, but in other embodiments, other molybdenum halide precursors may be used. The molybdenum halide precursor is given by the formula MoX z , where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and z is 2, 3, 4, 5, or 6. Examples of MoX z precursors include molybdenum fluoride (MoF 6 ). In some embodiments, a non-fluorine-containing MoX z precursor is used to prevent fluorine etching or incorporation. In some embodiments, a non-bromine-containing and / or non-iodine-containing MoX z precursor is used to prevent etching or bromine or iodine incorporation.

[0069] In some embodiments, the feature can be filled using an oxyhalomolybdenum precursor. The oxyhalomolybdenum precursor is given by the formula MoO y X z , where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and y and z are numbers greater than 0 such that MoO y X z forms a stable compound. Examples of oxyhalomolybdenum include molybdenum dichloride dioxide (MoO 2 Cl 2 ), molybdenum oxychloride (MoOCl 4 ), molybdenum oxyfluoride (MoOF 4 ), molybdenum dibromide dioxide (MoO 2 Br 2 ), as well as molybdenum iodide MoO 2 I, and Mo 4 O 11I. As used herein, the term molybdenum oxyhalide precursor can be understood to refer to the aforementioned molybdenum oxyhalide precursor, or a molybdenum-containing oxyhalide precursor containing molybdenum, oxygen, halide, and one or more other elements. In some embodiments, the molybdenum oxyhalide or molybdenum-containing oxyhalide can contain multiple different halogens (e.g., F and Cl and / or I and / or Br, etc.). The features can be filled with molybdenum using MoCl x precursor, MoO y X z precursor, or a combination thereof.

[0070] To deposit molybdenum on the features, the molybdenum precursor can be reacted with a co-reactant. Examples of co-reactants include hydrogen (H 2 ), silane (SiH 4 ), diborane (B 2 H 6 ), germane (GeH 4 ), ammonia (NH 3 ), and hydrazine (N 2 H 4 ).

[0071] In some embodiments, the deposition of molybdenum can use a plasma-based process. A gas can be supplied to a remote or in-situ plasma generator to generate plasma species. Examples of gases that can be used to generate plasma are hydrogen-containing gases such as H 2 , nitrogen-containing gases such as N 2 , and other gases such as Ar and NH 3 . The plasma species can be inert or can react with the molybdenum precursor to form a film.

[0072] The feature can be filled with molybdenum by atomic layer deposition (ALD) or chemical vapor deposition (CVD). Thermal ALD or plasma-enhanced ALD (PEALD) may be used. Similarly, thermal CVD or plasma-enhanced CVD (PECVD) can be used.

[0073] ALD is a surface-mediated deposition technique in which precursor and reactant doses are sequentially introduced into the deposition chamber. One or more cycles of sequential dosing of molybdenum precursor and reactant can be used to deposit Mo. For example, in the deposition of an initial molybdenum layer, MoCl 5 can be used as a precursor and H 2 can be used as a reducing agent. Doses of MoCl 5 and H 2 are sequentially introduced into the deposition chamber while flowing a purge gas such as argon in between. In the case of ALD, the temperature of the substrate and the pressure of the chamber can be controlled. For example, the substrate can be heated to 300 °C to 800 °C, for example, 650 °C to 750 °C. In some embodiments, the chamber can be pressurized to 10 Torr to 90 Torr, for example, 30 Torr to 50 Torr. In some embodiments, the reaction rate can be controlled using temperature and / or pressure. In some embodiments, selectivity can be controlled using temperature and / or pressure. This will be further explained below.

[0074] In some embodiments, molybdenum filling may involve CVD. In a CVD process, the molybdenum precursor and reactant are together in the gas phase within the deposition chamber. Generally speaking, the CVD process fills the feature faster than the ALD process. In one example, the precursor may be molybdenum chloride such as MoCl 5 and is flowed into the chamber along with a reactant such as H 2 . In this example, the wafer is simultaneously exposed to the precursor and reactant, and they react to fill the feature with Mo.

[0075] In some further embodiments, a pulse CVD process can be used to fill the features. In the pulse CVD process, reactants are continuously flowed into the chamber while pulses of precursors flow into the chamber. For example, H 2 gas is flowed into the chamber and H 5 gas can flow continuously into the chamber while MoCl 2 flows intermittently into the chamber. The temperature of the substrate and the pressure in the chamber can be controlled during the CVD operation.

[0076] Using the methods described herein, molybdenum can be selectively deposited onto the features. In selective deposition, the molybdenum fill can be more readily deposited on the first material as compared to the second material. For example, the deposition and growth of molybdenum can be more facile on a metallic material as compared to the deposition and growth of molybdenum on a dielectric material. For example, the feature can have sidewall surfaces of SiO 2 and a TiN plug at the bottom portion of the feature. In selective deposition, molybdenum is deposited onto the feature and grows on the TiN plug but does not grow (or grows to a lesser extent) on the SiO 2 sidewall surfaces. In this example, by growing molybdenum from the bottom of the feature on the TiN plug rather than on the sidewall surfaces, the feature avoids the effects of line bending described above with respect to FIG. 2L.

[0077] Process conditions such as precursor gas, reducing agent, process temperature, process pressure, and exposure time can affect the selectivity of the deposited molybdenum film. Different precursor gases can have different process windows in which the molybdenum film can be selectively deposited. For example, MoCl 5 has a higher selectivity than MoO 2 Cl 2 , i.e., under the same temperature and pressure conditions, the precursor gas of MoCl 5 deposits molybdenum only on the conductive surface and not on the dielectric surface, whereas MoO 2 Cl 2The precursor gas can deposit molybdenum on both the conductive surface and the dielectric surface. Generally speaking, MoCl 5 gas has a wide process window in which the precursor gas retains its selectivity, i.e., a wide temperature and pressure range. For example, MoCl 5 can be selectively deposited on the metal material compared to the dielectric material when the process temperature is 250 °C to 800 °C, for example, 300 °C to 500 °C. Generally speaking, when the process temperature is high and the process pressure is high, the selectivity of the deposition gas decreases. For example, at higher temperatures, precursor gases such as MoCl 5 may lose their selectivity and deposit molybdenum films on both the metal surface and the dielectric surface within the feature.

[0078] MoCl 5 can be reacted with different reactants to deposit a molybdenum film. Examples of the deposition of molybdenum films within features using MoCl 5 precursors and different process controls are described below. In the first example, the MoCl 5 precursor reacts with a hydrogen (H 2 ) reactant using the deposition method described above. In the description of this specification, the metal precursor reacts with hydrogen (H 2 ), which is also called a co-reactant (hydrogen reactant or H 2 ) reactant. However, instead of hydrogen, other reactants including other hydrogen-containing reactants such as SiH 4 , B 2 H 6 , NH 3 etc. can be used as appropriate. Reactants such as B 2 H 6 and / or SiH 4 are stronger reducing agents, but they can also result in higher resistivity. Therefore, in some embodiments, H 2It is advantageous to use. The process temperature for the selective deposition of the molybdenum film may be 250 °C to 800 °C, for example, 300 °C to 500 °C. At these temperatures, the molybdenum film is selectively deposited on the surface of a conductive metal or metal compound such as a TiN surface in the feature as compared to the dielectric surface. The molybdenum film grows from the location where the conductive surface in the feature is located. If the conductive surface is a TiN plug at the bottom of the feature, the molybdenum film can be deposited and grown from the bottom of the feature. In a second example, the molybdenum film can be deposited at a higher temperature, i.e., a temperature exceeding 800 °C, using a MoCl 5 precursor and an H 2 reagent. This process window may deposit a molybdenum film on both the dielectric surface and the conductive surface within the feature. The deposition of the molybdenum film on the dielectric surface can be used to form a barrierless molybdenum layer in the feature, which will be described in more detail below.

[0079] In yet another example, a MoCl 5 precursor is reacted with an ammonia (NH 3 ) reagent, and a molybdenum film is deposited on the feature using the deposition process described above. In this embodiment, the deposition of the molybdenum film may have a process temperature of 200 °C to 700 °C. The reaction of MoCl 5 with NH 3 may be less selective than reacting with H 2 at a similar temperature. In this embodiment, the molybdenum film can be deposited on both the dielectric surface and the conductive surface in the feature. The composition and crystallinity of the deposited film can be controlled using a temperature process. At a lower process temperature, generally less than 400 °C, an amorphous molybdenum nitride film is deposited. At a higher process temperature, generally exceeding 500 °C, a crystalline molybdenum nitride film can be deposited. Between these ranges, a partially crystalline film having amorphous and crystalline regions can be deposited.

[0080] In a method for filling features with a molybdenum film, an etching operation can be used. By the etching operation, materials such as metal and nitride are removed from the features. For example, the etching process can partially or completely remove the liner layer from the features. In another example, the etching process can be used to reduce the thickness of the liner layer. The etching operation may involve immersing the features in a molybdenum precursor gas in some embodiments. In some embodiments, the etching operation involves immersing the features with a MoCl 5 precursor such as MoCl x . In some embodiments, the immersion may be performed continuously using the precursor gas. In some embodiments, the immersion is pulsed and the MoCl x precursor can be circulated with a purge gas such as argon (Ar). In still some other embodiments, the features may be exposed to an alternative dosage of the MoCl x precursor and a reactant such as H 2 .

[0081] The MoCl x precursor can be used for both the deposition operation and the etching operation. For example, in a specific process window, the MoCl 5 precursor can grow a molybdenum film and simultaneously etch and remove a metal or metal compound film in the features. The process is considered a net etching operation when the rate of the material being removed is greater than the material deposited by the precursor. The rate at which the precursor deposits and etches the material can be controlled by various process conditions including the type of reactant used and the process temperature. Generally speaking, the lower the temperature, the higher the ratio of the etching removal of the material to the deposition of the material. At a higher temperature, the same precursor and reactant can be used as a net deposition operation, that is, the amount of material deposited is more than the material removed. For example, when the process temperature is less than 400 °C, the MoCl 5 precursor and H 2The reactant can be used for the etching operation. When the process temperature exceeds 550 °C, MoCl 5 and H 2 The same precursor of the reactant can be used in the deposition operation.

[0082] In some embodiments, at high temperatures, e.g., above 550 °C, MoCl x precursor may continue to etch the material at a faster rate than depositing the material. For example, it is possible to etch features by immersion without a reactant using MoCl 5 . In this example, the temperature can reach up to 700 °C and will continue to etch away the material from the feature. In the operation where the feature is immersed in MoCl 5 without a reactant, as the temperature increases, the rate at which the material is etched from the feature can increase.

[0083] The feature may have surface oxides or contaminants. For example, the surface of the underlying TiN, WN, or W layer can be oxidized. If left untreated, the resistivity of the oxidized surface may increase. A cleaning operation is used to remove such oxides and contaminants. In some embodiments, the cleaning operation may involve a feature immersed in a molybdenum precursor gas, typically molybdenum halide. Similar to the etching operation described above, the precursor gas may be a MoCl x precursor. In some embodiments, the immersion may be continuous. In some embodiments, the immersion is pulsed and a purge gas such as MoCl x and argon (Ar) can be circulated. The precursor may be a non-oxygen Cl-containing molybdenum compound capable of removing oxidation from the surface of the feature. Examples of MoCl x compounds are given above. When the oxidized surface is stable on the surface material, such as heat or plasma H 2When conventional cleaning by [method] does not function, a Cl-containing precursor can be used. The Cl-containing precursor is less likely to overetch the liner layer of the feature or attack the surface of the feature than an F-containing compound.

[0084] In some embodiments, filling the feature can involve depositing a nucleation layer. The nucleation layer is a thin layer that supports bulk deposition. The nucleation layer can be conformal to the feature. In many embodiments, the nucleation layer is deposited by an ALD process. In some embodiments, a molybdenum nucleation layer uses one or more of a boron-containing reducing agent (e.g., B 2 H 6 ) or a silicon-containing reducing agent (e.g., SiH 4 ) as a co-reactant for deposition. For example, one or more S / molybdenum cycles or Mo / S cycles can be used to deposit the molybdenum nucleation layer. In another example, one or more B / molybdenum cycles or Mo / B cycles can be used to deposit the molybdenum nucleation layer, and a bulk molybdenum layer can be deposited thereon. B refers to a pulse of diborane or other boron-containing reducing agent, S refers to a pulse of silane or other silicon-containing reducing agent, and thus S / molybdenum refers to a pulse of silane followed by a pulse of a Mo-containing precursor. Both B / molybdenum cycles and S / molybdenum cycles (or Mo / B and / or Mo / S) can be used to deposit a molybdenum nucleation layer, e.g., x(B / Mo)+y(S / Mo), where x and y are integers. Examples of boron-containing reactants include diborane (B 2 H 6 ), alkylboranes, alkylborons, aminoboranes (CH 3 ) 2 NB(CH 2 ) 2 , carboranes such as C 2 B n H n+2 , and other boranes. Examples of boranes include B n H n+4 , B n H n+6 , Bn H n+8 , B n H m are mentioned, n is an integer from 1 to 10, and m is an integer different from m. Examples of silicon-containing reducing agents include silane (SiH 4 ), and other silanes such as disilane (Si 2 H 6 ).

[0085] In some embodiments, the deposition of the molybdenum nucleation layer may involve the use of a non-oxygen-containing precursor, such as molybdenum hexafluoride (MoF 6 ) or molybdenum pentachloride (MoCl 5 ). Oxygen in the oxygen-containing precursor may react with the silicon- or boron-containing reducing agent to form an impure high-resistance film of MoSi x O y or MoB x O y . In some embodiments, the oxygen-containing precursor may be used for depositing the nucleation layer while minimizing oxygen uptake. Oxygen uptake can be minimized by a high reducing agent flow rate (e.g., the volume flow rate of the reducing agent relative to the oxygen-containing molybdenum precursor exceeds 100:1).

[0086] In some embodiments, H 2 can be used as the reducing gas for depositing the molybdenum nucleation layer instead of the boron-containing or silicon-containing reducing gas. An exemplary thickness for depositing the molybdenum nucleation layer ranges from 5 Å to 30 Å. The film at the lower limit of this range may not be continuous, but its thickness may be sufficient as long as it can help initiate continuous bulk molybdenum growth.

[0087] In some embodiments, the reducing agent pulse during the deposition of the nucleation layer or the bulk molybdenum layer may be performed at a lower substrate temperature than the molybdenum precursor pulse. For example, or B 2 H 6 or SiH 4(Or other boron- or silicon-containing reducing agents) pulses are carried out at temperatures below 300 °C, and molybdenum pulses can be carried out at temperatures above 300 °C.

[0088] In some embodiments, the reducing agent is NH 3 , or another nitrogen-containing reducing agent such as hydrazine (N 2 H 4 ). Chemisorption of NH 3 on the dielectric is more favorable than chemisorption of H 2 . In some embodiments, the reducing agent and the precursor are selected such that the reducing agent reacts without dissociating. NH 3 reacts with metal oxyhalides and metal halides without dissociating. This is in contrast to ALD from metal oxyhalides using H 2 as a reducing agent, for example, where H 2 dissociates on the surface to form adsorbed atomic hydrogen, resulting in a very low concentration of reactive species and a low surface coverage during initial nucleation of the metal on the dielectric surface. By using NH 3 and a metal oxyhalide or metal halide precursor, nucleation delay is reduced or eliminated at deposition temperatures that are several hundred degrees lower than those used by H 2 reduction of the same metal precursor.

[0089] In some embodiments, the reducing agent may be a boron-containing or silicon-containing reducing agent such as B 2 H 6 or SiH 4 . These reducing agents can be used with metal halide precursors, metal oxyhalides, but B 2 H 6 and SiH 4 may react with water formed as a byproduct during the ALD process to form solid B 2 O 3 and SiO 2 . These are insulating and may remain in the film, potentially increasing the resistivity. By using NH 3 , B 2 O 3 on certain surfaces containing2 H 6 and SiH 4 The adhesion is improved compared to the ALD process. The resulting nucleation layer is generally not a pure elemental film but a metal nitride or metal oxynitride film. In some embodiments, especially when the deposition is carried out at low temperature, there may be residual chlorine or fluorine from the deposition. In some embodiments, the residual chlorine or fluorine may be present in trace amounts. In some embodiments, the nucleation layer is an amorphous layer. Impurities in the film (e.g., oxygen, NH 3 , chlorine, or other halogens) promote the growth of the amorphous microstructure. In some embodiments, the deposited nucleation layer is an amorphous molybdenum oxynitride layer or an amorphous molybdenum nitride layer. The amorphous properties template the growth of large particles in the subsequently deposited conductor. The surface energy of the nitride or oxynitride with respect to the oxide surface is much more favorable than the surface energy of the metal on the oxide surface, facilitating the formation of a continuous and smooth film on the dielectric. This enables the formation of a thin continuous layer. An exemplary thickness of the nucleation layer ranges from 5 to 30 Å during deposition. Depending on the temperature, this can be, for example, about 5 to 50 ALD cycles.

[0090] As described below, during subsequent processing, the nucleation layer can be converted into a pure (or not very impure) elemental metal film with a decreasing thickness. The surface on which the nucleation layer is deposited depends on the specific application. In some embodiments, the nucleation layer is deposited directly on the surface of a dielectric (e.g., silicon oxide, aluminum oxide, silicon nitride, etc.). In some embodiments, the nucleation layer is deposited directly on titanium nitride or other surfaces.

[0091] In some embodiments, ALD formation of the molybdenum layer can be initiated by a reducing agent layer. An example of such a process is shown in the flowchart of FIG. 3. In operation 302, 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. Further examples of reducing agents are shown below. In some embodiments, the reducing agent layer may include silicon or a silicon-containing material, phosphorus or a phosphorus-containing material, germanium or a germanium-containing material, boron or a boron-containing material capable of reducing the molybdenum precursor, and combinations thereof. According to various embodiments, hydrogen may or may not flow in the background. (Although hydrogen can reduce tungsten precursors, it does not function as a reducing agent in a gas mixture containing a sufficient amount of a stronger reducing agent such as silane or diborane.) 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 boron-containing gas can have a significant impact on the decomposition and adhesion coefficient of other reducing agents. Note that sequential exposure of the substrate to two reducing agents, for example, silane and diborane, can be performed. However, by flowing a gas mixture, it is possible to facilitate the addition of a very small amount of minority gas, for example, a ratio of silane to diborane of at least 100:1. In some embodiments, a carrier gas can be flowed. In some embodiments, a carrier gas such as nitrogen (N 2 )), argon (Ar), helium (He), or other inert gas may be flowed during operation 302.

[0092] In some embodiments, the reducing agent layer may include elemental silicon (Si), elemental boron (B), elemental germanium (Ge), or a mixture thereof. For example, the reducing agent layer can include elemental Si and B. This may involve the decomposition of compounds in the reducing agent gas, unlike adsorbed silane or diborane molecules. The amount of B can be adjusted to achieve a high deposition rate of the reducing agent layer with a low resistivity. In some embodiments, the reducing agent layer may have, for example, 5% - 80% B, or 5% - 50% B, 5% - 30%, or 5% - 20% B, with the remainder consisting essentially of Si and optionally H. Hydrogen atoms, e.g., SiH x , BH y , GeH z , or a mixture thereof are present, and x, y, and z can independently be between 0 and a number less than the stoichiometric equivalent of the corresponding reducing agent compound. In some embodiments, the composition can vary through the thickness of the reducing agent layer. For example, the reducing agent layer may have 20% B at the bottom of the reducing agent layer and 0% B at the top of the layer. The total thickness of the reducing agent layer may be 10 Å - 50 Å, and in some embodiments, 15 Å - 40 Å, or 20 Å - 30 Å. The reducing agent layer conformally coats the features.

[0093] The substrate temperature during operation 302 can be maintained at a temperature T1 at which the film becomes conformal. If the temperature is too high, the film may not conform to the topography of the underlying structure. In some embodiments, step coverage of 90% or more than 95% is achieved. In the case of silane, diborane, and silane / diborane mixtures, the conformality is excellent at 300 °C but may deteriorate at temperatures of 400 °C or higher. Thus, in some embodiments, the temperature during operation 302 is at most 350 °C, or at most 325 °C, at most 315 °C, or even at most 300 °C. In some embodiments, a temperature below 300 °C is used. For example, the temperature may be on the order of 200 °C.

[0094] Operation 302 can be carried out over any suitable duration. In some examples, exemplary durations include from about 0.25 seconds to about 30 seconds, from about 0.25 seconds to about 20 seconds, from about 0.25 seconds to about 5 seconds, or from about 0.5 seconds to about 3 seconds.

[0095] In operation 304, the chamber is optionally purged to remove excess reducing agent that did not adsorb to the surface of the substrate. The purge is performed by flowing an inert gas at a constant pressure, whereby the pressure of the chamber can be reduced and the chamber can be repressurized before starting another gas exposure. Exemplary inert gases include nitrogen (N 2 ), argon (Ar), helium (He), and mixtures thereof. The purge can be carried out over a duration of from about 0.25 seconds to about 30 seconds, from about 0.25 seconds to about 20 seconds, from about 0.25 seconds to about 5 seconds, or from about 0.5 seconds to about 3 seconds.

[0096] In operation 306, the substrate is exposed to a molybdenum precursor at a substrate temperature T2. The use of an oxygen-containing precursor may result in impurity incorporation and higher resistivity. However, if oxygen is incorporated, a very thin and in some cases discontinuous reducing agent layer can be used to obtain an acceptable resistivity. In some embodiments, during operation 306, nitrogen (N 2 ), argon (Ar), helium (He), or other inert gas such as a carrier gas can be flowed. An example of the temperature is from 500 °C to 700 °C.

[0097] Operation 306 can be carried out over any suitable duration. In some embodiments, this may involve immersion of the molybdenum precursor, and in some embodiments, it may involve a series of molybdenum precursor pulses. According to various embodiments, operation 306 may or may not be carried out in the presence of H 2 . If H 2 is used, in some embodiments, H 2 and the Mo-containing precursor can be applied in an ALD-type mode. For example: Pulses of H 2 ​ Argon purge H in the background 2 Pulses of Mo-containing precursors, with or without Argon purge Repeatedly

[0098] 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 a conversion rate of 100% or nearly so. The resulting feature is here lined with a conformal film of Mo. The feature may be 10 Å to 50 Å, and in some embodiments, 15 Å to 40 Å, or 20 Å to 30 Å. Generally, the feature is approximately the same thickness as the reducing agent layer. In some embodiments, the feature can be up to 5% thicker than the reducing agent layer due to volume expansion during conversion. The chamber can be purged in operation 308. Most of the feature can be filled by deposition of a bulk molybdenum layer. The bulk molybdenum layer can be deposited directly on the nucleation layer, on the reducing agent layer, or on the surface of the underlying layer as described above.

[0099] Bulk deposition can be performed by an ALD or CVD process. In a CVD process, the reducing agent and the molybdenum precursor are flowed in parallel into the deposition chamber to deposit a bulk filling layer on the feature. An inert carrier gas can be used to feed one or more of the reactant streams, which may or may not be premixed. This operation generally involves flowing the reactants continuously until the desired amount is deposited. In certain embodiments, the CVD operation can be performed in multiple stages, with multiple periods of continuous and simultaneous flow of the reactants separated by periods during which the flow of one or more of the reactants is diverted.

[0100] In some embodiments, a pulsed CVD process can be used in which H 2 or other co-reactants flow continuously while the molybdenum precursor is pulsed.

[0101] In the case of conformal deposition and deposition onto complex structures such as 3D NAND structures, ALD deposition of the bulk layer can be used. The ALD deposition of the bulk layer involves exposure to alternating pulses of a molybdenum-containing precursor and a reducing agent separated by an inert purge gas, using the molybdenum precursors described above. The same or different molybdenum precursors used in the deposition of the nucleation layer or the reducing agent layer may be used for the bulk deposition. In contrast to the nucleation layer deposition where a strong reducing agent such as diborane or silane can be used, hydrogen is often the reducing agent in the bulk deposition.

[0102] In some embodiments, the nucleation layer can be converted to an elemental molybdenum layer. This can also be characterized as removing impurities, i.e., any non-metallic components. The nucleation layer may have more impurities than the subsequently deposited elemental molybdenum layer, but they are removed sufficiently such that the resistivity of the stack is the same or similar to that of a stack without the nucleation layer. As described above, in some embodiments, a molybdenum oxynitride layer or a molybdenum nitride layer can be used as the nucleation layer. Also, in some embodiments, a molybdenum oxide layer can be used as the nucleation layer.

[0103] According to various embodiments, one or more of the following can be used to facilitate the conversion of the nucleation layer to an elemental molybdenum film: 1) deposition of a bulk molybdenum layer at a temperature higher (e.g., 550 °C) than at which the nucleation layer is deposited, 2) implementation of low-temperature ALD H 2 / molybdenum precursor cycles, and 3) in-situ deposition of the bulk molybdenum layer such that the nucleation layer is not exposed to air or oxidized prior to the bulk deposition of molybdenum. In particular, molybdenum oxynitride is relatively easy to convert to the elemental metal. The resulting converted nucleation layer and pure metal layer can each be characterized as having less than 1% atomic impurities.

[0104] As described above with reference to FIG. 1B, molybdenum can be deposited on the feature without a barrier layer, i.e., molybdenum is deposited on the dielectric surface in the feature. In some embodiments, a reducing agent layer as described above with reference to FIG. 3 can be used. In these embodiments, the reducing agent can be deposited on the feature. As described in operation 308, subsequent deposition using a molybdenum precursor can convert the reducing agent layer to Mo. In some embodiments, molybdenum can be directly deposited on the dielectric layer by a CVD or ALD process using a molybdenum chloride or molybdenum oxyhalide precursor and the reactant described above.

[0105] In a first example, molybdenum can be deposited on a feature having a dielectric surface such as SiO 2 using a seed crystal. This process uses a molybdenum chloride precursor such as MoCl 5 and a reactant such as H 2 In some embodiments, NH 3 can be used as the reactant. As described above, MoCl 5 is highly selective and may resist direct growth on the dielectric surface compared to the conductive surface. However, when the precursor and reactant are given a sufficiently long exposure time to the SiO 2 surface, molybdenum seed crystals are formed on the SiO 2 The exposure time of the molybdenum precursor and reactant to form seed crystals on the dielectric material is longer than the typical exposure time when depositing molybdenum on the nucleation layer or plug due to the selectivity of the precursor. Once the seed crystals are formed on the dielectric layer, molybdenum can be selectively deposited on the seed crystals formed using the same precursor and reactant.

[0106] The formation of seed crystals can involve one or more of the following. In some embodiments, exposing the molybdenum chloride precursor and a reactant such as H 2 to the SiO 2 surface for a long time forms molybdenum seed crystals on the SiO 2 For example, the molybdenum seed crystals are MoCl as the precursor.5 is used, and H is used as a reactant 2 can be formed on the dielectric material after 200 - 600 ALD cycles using. In another embodiment, a relatively large amount of reactant deposition compared to the precursor can be used to generate molybdenum species crystals on the dielectric surface. During the formation of molybdenum species crystals, the concentration of the precursor is reduced, and thus the ratio of the reactant to the deposited precursor may increase. MoCl 5 precursor and H 2 In an example using a reactant, for MoCl 5 to H 2 when the ratio is relatively high, the deposition delay on the dielectric material is shortened and the generation of seed crystals is accelerated. In the case of seed crystal formation, the concentration of the precursor gas can be reduced to up to one-tenth, for example, one-fifth of the normal precursor concentration during normal deposition operation. For example, in a typical ALD process, the precursor concentration may be 1 - 2% of the gas, that is, 98% of the gas is the carrier gas and 2% is the precursor. In seed crystal formation, the precursor concentration can be reduced to up to one-tenth to be about 0.1% of the gas. In some embodiments, the process temperature can be increased to improve seed crystal formation. For example, the process temperature during seed crystal formation may exceed 500°C. In some embodiments, the temperature during seed crystal formation may exceed 500°C and may be reduced to less than 500°C to selectively grow molybdenum on the seed crystals formed on the dielectric material.

[0107] In some embodiments, molybdenum oxyhalides such as MoO 2 Cl 2 can be used as precursors to form molybdenum species crystals on the dielectric surface. In these embodiments, the seed crystals can be formed on the dielectric material faster than the seed crystals formed using molybdenum chloride precursors. However, the deposited molybdenum film may be oxidized.

[0108] In some embodiments, molybdenum can be selectively deposited onto a conductive metal plug formed in a feature. In these embodiments, the feature can have a plug made of a conductive metal, such as TiN, at the bottom of the feature onto which molybdenum is selectively deposited. The feature may also have sidewall surfaces made of a dielectric material. Using the above-described selective deposition techniques (i.e., controlling process parameters such as temperature, pressure, and reactants), molybdenum can be deposited using a molybdenum halide or oxyhalide precursor such that molybdenum is selective to the conductive metal plug. Molybdenum grows on the conductive metal plug rather than on the dielectric sidewalls.

[0109] In embodiments where the feature does not have a conductive metal plug, a molybdenum plug can be formed at the bottom of the feature by depositing a molybdenum chloride precursor and a hydrogen reactant using the methods described above. The molybdenum plug can be formed when deposition is carried out using (i) a relatively high ratio of molybdenum chloride precursor to the reactant, (ii) a relatively high process pressure compared to selective deposition, or (iii) a combination thereof. In some embodiments, when deposition is carried out on the feature using a high ratio of molybdenum chloride precursor, a net etching effect occurs on the upper part of the feature and a net deposition effect occurs at the bottom of the feature, enabling the formation of a molybdenum plug on the bottom of the feature. The bottom of the feature is the innermost surface of the feature connected by the sidewalls. In some embodiments, the molybdenum plug can be formed at a lower temperature, for example, less than 450 °C. The molybdenum plug can be formed using a CVD or pulsed CVD process. In an example of a pulsed CVD process, the H 2 reactant may flow continuously into the feature, and MoCl 2 reactant may be pulsed into the feature. 5The precursor may be pulsed at a concentration of 0.1% to 2% for a duration of 0.5 to 2.5 seconds. When a molybdenum plug is formed at the bottom of the feature, it is possible to change the process parameters and selectively deposit molybdenum on the molybdenum plug within the feature.

[0110] FIG. 4 is a process flow diagram showing a method of filling a feature with a molybdenum (Mo) film. Method 400 begins, in operation 401, with providing a substrate that includes a feature on which molybdenum is to be deposited. The substrate may be provided to a semiconductor processing tool. The feature can be a trench, a via, or any of the features described above with reference to FIGS. 2A - 2L. In some embodiments, the feature is formed in a dielectric material. Molybdenum can be deposited in the feature and electrically contacted to an underlying layer. Examples of underlying layers include metals, metal silicides, and semiconductors. Examples of metals include Co, Ru, copper (Cu), W, Mo, nickel (Ni), iridium (Ir), rhodium (Rh), tantalum (Ta), and Ti. Examples of metal silicides include TiSi x , nickel silicide (NiSi x ), molybdenum silicide (MoSi x ), cobalt silicide (CoSi x ), platinum silicide (PtSi x ), ruthenium silicide (RuSi x ), and nickel platinum silicide (NiPt y Si x ). Examples of semiconductors include silicon (Si), silicon germanium (SiGe), and gallium arsenide (GaAs) with or without semiconductor dopants such as carbon (C), arsenic (As), boron (B), phosphorus (P), tin (Sn), and antimony (Sb).

[0111] Features generally have sidewall surfaces and may also have a bottom surface. In some embodiments, the sidewall surfaces may be of the same material as the bottom surface. For example, in some embodiments, the sidewall surfaces and the bottom surface are TiN. In some embodiments, the sidewall surfaces may be of a material different from that of the bottom surface. For example, the bottom surface may be a metal silicide, and the sidewall surfaces may be silicon oxide such as SiO 2 etc. In some embodiments, the feature may have sloped sidewall surfaces. In some such embodiments, the sidewall surfaces intersect at the bottom of the feature.

[0112] Prior to molybdenum deposition, a liner layer can line the unfilled feature and form the sidewall surfaces and / or the bottom surface. In some embodiments, the liner layer lines the entire feature and forms the sidewall surfaces and the bottom surface. In some other embodiments, the liner layer lines only a portion of the feature. For example, a TiN layer can line the sidewalls and the bottom surface is not lined. Examples of materials for the liner layer include metal nitrides (e.g., TiN or tantalum nitride (TaN) barrier layers) and metals (e.g., Ti adhesion layers).

[0113] In some embodiments, the feature surface is oxidized. Oxidation may be caused by exposing the surface of the feature to air or other oxidizing conditions. For example, the surface of a metal silicide (MSi x , where M is a metal) can be oxidized to metal silicide oxide (MSi x O y ) when exposed to air. Other examples of oxidized surfaces include metal nitride oxides (MN x O y ), silicon oxide (SiO x ), and silicon germanium oxide (SiGeO x ). (In the description of this specification, subscripts x and y are used in the formulas to indicate non-zero numbers.)

[0114] In some embodiments, oxidation conditions occur during the processing or transfer operations of the substrate. In some embodiments, intentional oxidation is performed as further described below with reference to FIG. 5.

[0115] After providing a substrate including features on which molybdenum is to be deposited, an optional cleaning operation 402 can be performed. Optional cleaning can be used to remove oxides on the surface of the features. In some embodiments, an in-situ cleaning process as described above can be used. In in-situ cleaning, molybdenum halides such as MoCl 5 can be used. In some embodiments, a hydrogen plasma treatment, a hot hydrogen treatment, or a reduction treatment can be used to reduce the metal oxide on the metal substrate at the bottom of the feature. In some embodiments, atomic layer cleaning using a Cl-based plasma, hydrogen fluoride (HF) vapor cleaning, ammonium fluoride (NH 4 F) cleaning, or a treatment using other reducing agents can be used to reduce the oxide from the surface of the feature.

[0116] When the substrate is provided, in operation 403, an initial molybdenum layer is deposited on the features. The initial molybdenum layer is deposited by ALD. The initial molybdenum layer is deposited by sequentially introducing a molybdenum precursor and a reducing agent into the deposition chamber. One or more cycles of sequential dosing of the molybdenum precursor and the reducing agent can be used to deposit the initial molybdenum layer. In some embodiments, the initial molybdenum layer can be deposited conformally on the features. The conformal molybdenum layer can be, in some embodiments, 1 to 5 nm. In some embodiments, the conformal molybdenum layer has a thickness of 2 nm or less. In some embodiments, molybdenum can be deposited non-conformally, for example, by depositing a molybdenum plug at the bottom of the feature, such that it is selectively deposited on the bottom of the feature compared to the sidewalls.

[0117] In the deposition of the initial molybdenum layer, the molybdenum precursor is a molybdenum halide precursor. MoClx Precursors are used in some embodiments. As described above, other MoX z Precursors may be used in other embodiments. Examples of reducing agents used are those described above. The non-oxygen-containing molybdenum precursor prevents oxidation of the surface of the feature. This also prevents oxygen from being incorporated into the initial molybdenum layer. Oxidation increases the contact resistance. Since there is no oxidation and no oxygen incorporation, it is ensured that the contact resistance remains low.

[0118] During the ALD process, the temperature of the substrate and the pressure of the chamber can be controlled. In some embodiments, the substrate can be heated at 300 °C to 500 °C, for example, 350 °C to 450 °C. In some embodiments, the chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr.

[0119] In some embodiments, the selectivity can be controlled using process parameters such as temperature. For example, molybdenum can be selectively deposited on a metal silicide surface or a metal nitride surface relative to the surface of the dielectric material by using a lower temperature than in the case of conformal deposition. For example, in some embodiments, a temperature of less than 400 °C is used.

[0120] After the initial molybdenum layer is deposited, in operation 405, the feature is filled with molybdenum using an oxyhalogenated molybdenum precursor. As shown above, MoO y X z Examples of precursors include MoO 2 Cl 2 MoOCl 4 MoOF 4 MoO 2 Br 2 MoO 2 I, and Mo 4 O 11 I. The feature can be filled using ALD, plasma-enhanced ALD, chemical vapor deposition (CVD), or plasma-enhanced CVD. In the case of ALD or CVD, H 2can be a reducing agent. Molybdenum is used to form an initial molybdenum layer, such as MoCl x The molybdenum oxyhalide precursor is deposited more rapidly by using it instead of the precursor. For example, MoO y X z The precursor can deposit molybdenum at a deposition rate at least twice that of the MoCl x precursor in the case of a non-plasma process. A plasma-enhanced process can be used to fill features at lower temperatures and / or increase the deposition rate.

[0121] FIG. 5 is a process flow diagram showing an in-situ cleaning method for cleaning an oxidized feature. Method 500 begins at operation 501 by providing a substrate including a feature having one or more oxidized surfaces. The substrate may be provided to a semiconductor processing tool.

[0122] Similar to the feature referred to in operation 401 of FIG. 4, the feature has sidewall surfaces and may have a bottom surface. In some embodiments, the feature can be formed in a dielectric layer as a trench or via for connecting to a lower layer. Other examples of features are described above in FIGS. 2A-2L. Examples of materials for forming a bottom surface and sidewall surfaces including a liner layer are given above with reference to operation 401 of FIG. 4. In the description of this specification of FIG. 5, the feature has a bottom surface and sidewall surfaces. It should be understood that the method can be used for any feature provided on a substrate having an oxidized surface.

[0123] The provided feature has at least one oxidized surface. In some embodiments, both the bottom surface and the sidewall surface are oxidized. In some other embodiments, only some surfaces (e.g., only the bottom surface) are oxidized. The oxidized surface can be caused by exposing the surface to oxidation conditions. Examples of oxidation conditions include exposing the surface to air and treating the surface with an oxygen-based heat or plasma treatment. In some embodiments, oxidation conditions occur during the processing or transfer operation of the substrate. In some embodiments, intentional oxidation is performed. An example of the oxidized surface is given above with reference to FIG. 4.

[0124] After providing the substrate, optional intentional oxidation of the surface can be performed. Intentional oxidation can occur by exposing the surface to air or treating the surface with an oxygen-based heat treatment or an oxygen plasma treatment. Intentional oxidation of the surface can be used to increase the oxidation of a liner layer, e.g., a TiN barrier layer. This increases the amount of the liner layer removed during in-situ cleaning. Thinning the liner layer in this way reduces the resistance in the feature.

[0125] After providing a substrate including a feature on which molybdenum is deposited, an optional cleaning operation 502 can be performed. Optional cleaning can be used to remove oxides on the surface of the feature. In some embodiments, a hydrogen plasma treatment, a hot hydrogen treatment, or a reduction treatment is used to reduce the metal oxide on the metal substrate at the bottom of the feature. In some embodiments, atomic layer cleaning using a Cl-based plasma, hydrogen fluoride (HF) vapor cleaning, ammonium fluoride (NH 4 F) cleaning, or a treatment using other reducing agents can be used to reduce the oxides on the feature surface.

[0126] Next, in operation 503, the feature undergoes immersion. The feature is immersed in molybdenum chloride (MoCl to remove oxidation from the surface of the feature. x) It is immersed in the precursor. In some embodiments, the immersion may be performed continuously. In some embodiments, the immersion is pulsed, and a purge gas such as MoCl x and argon (Ar) can be circulated. The precursor is a non-oxygen Cl-containing molybdenum compound that can remove oxidation from the surface of the feature. Examples of MoCl x compounds are given above. When the oxidized surface is stable on the surface material, such as when conventional cleaning with heat or plasma H 2 does not function, a Cl-containing precursor can be used.

[0127] In one example, the feature can have a TiN barrier layer as its liner layer. The liner layer is oxidized to form a TiN x O y surface layer. Since TiN x O y is stable, the H 2 process may not be able to efficiently remove TiN x O y from the TiN layer. When the feature is immersed in a MoCl 5 such as MoCl x precursor, oxides are effectively removed from the TiN liner layer. In the case of a relatively thin liner, an F-based precursor such as tungsten fluoride (WF 6 ) may cause over-etching of the liner. The F-based precursor may attack the surface of the underlying layer, such as the bottom surface of the feature. The in-situ cleaning process of FIG. 5 prevents over-etching of the TiN liner and attack on the surface of the underlying layer. In one example of the TiN barrier layer, the F-based precursor may attack the surface of the underlying layer and / or the metal silicide of the underlying layer.

[0128] In the case of in-situ cleaning, the temperature of the substrate, the pressure in the chamber of the semiconductor processing tool, and the exposure time of the precursor to the feature can be controlled. In some embodiments, the substrate can be heated at 300°C to 500°C, for example, 350°C to 450°C. In some embodiments, the chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr. The total exposure time of the precursor to the feature may be at least 10 seconds, for example, at least 60 seconds. As shown above, the immersion may be continuous or pulsed.

[0129] After the feature is immersed and the oxidation is removed from the surface of the feature, in operation 505, molybdenum is deposited on the feature using MoCl x The molybdenum deposition uses the same precursor MoCl as that used to immerse the feature in operation 503 x The deposited molybdenum is the initial molybdenum layer. In some embodiments, operation 505 may involve filling the feature using MoCl 5 In some other embodiments, the feature can be filled using a molybdenum oxyhalide precursor MoCl y X z Examples of molybdenum oxyhalide precursors are given above. The feature can be filled using ALD or CVD, including the thermal and plasma enhanced ALD and CVD processes described above.

[0130] Feature filling may be non-selective or selective according to various embodiments. In some embodiments, the feature filling is selective to partially fill the feature, and then more conformal filling can be performed to complete the feature filling. Non-selective deposition may be described herein as conformal deposition in that the deposited layer conforms to the contour of the underlying feature. Such a deposited layer may have some thickness non-uniformity.

[0131] In the filling process of operation 505, the temperature of the substrate, the pressure of the chamber, and the exposure time of the reactant can be controlled. Using these process parameters, it is possible to control the selectivity during the bulk filling of Mo. As in the operation of 503, the substrate can be heated at 300°C to 500°C, for example, 350°C to 450°C. The chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr. The exposure time of the reactant may be at least 5 seconds, for example, at least 15 seconds.

[0132] Figure 6 is a process flow diagram showing a method of filling a feature having a protective nitride layer with a molybdenum film. The protective nitride layer can be used to protect the material of the lower layer under the bottom and the bottom surface of the feature. Method 600 begins with providing a substrate having a metal nitride layer in operation 601. The substrate may be provided to a semiconductor processing tool.

[0133] Similar to the feature referred to in operation 401 of Figure 4, the feature generally has a bottom with a bottom surface and a side with a side wall surface. The feature can be formed in a dielectric layer and connected to the underlying layer. Examples of materials forming the bottom and the side wall are given above with reference to operation 401 of Figure 4.

[0134] In the provided feature, the bottom surface is a metal nitride layer. Examples of metal nitrides are TiN and TiSiN. In some embodiments, the metal nitride layer can conformally line the feature such that the side wall surface and the bottom surface are the metal nitride layer. In some embodiments, the side wall surface may be a material different from that of the bottom surface. For example, the bottom surface may be a metal nitride layer and the side wall surface may be a dielectric material.

[0135] In some embodiments, the bottom surface and the sidewall surfaces are oxidized. Oxidation may be caused by exposing the surface of the feature to air or other oxidation conditions. In some embodiments, oxidation conditions occur during the processing or transfer operations of the substrate. In some embodiments, as described above with respect to FIG. 5, intentional oxidation is performed.

[0136] After providing a substrate having a metal nitride layer, at operation 602, optional cleaning and / or optional etching can be performed. Cleaning can be used to remove oxides from the field, sidewall surfaces, and bottom surface of the feature, while optional etching can be used to remove a portion of the metal nitride layer on the sidewalls or field of the substrate. An example of a cleaning process is given above at operation 502 of FIG. 5.

[0137] When performed, operation 602 can involve immersing the feature in a molybdenum precursor to remove oxidation and / or removing or reducing the metal nitride layer from the feature. In some embodiments, the immersion may be performed continuously. In some embodiments, pulse immersion is used and the precursor gas can be circulated while flowing a purge gas. In some embodiments, the precursor gas can be circulated alternately with the purge gas. The precursor gas may be a molybdenum-containing halide compound. In some embodiments, the precursor gas is MoCl x , for example, MoCl 5 . Examples of other MoCl x precursors are given above.

[0138] In the cleaning / etching operation of 602, the temperature of the substrate, the pressure of the chamber in the semiconductor processing tool, and the exposure time of the precursor to the feature can be controlled. In some embodiments, the substrate can be heated at 300°C to 500°C, for example, 350°C to 450°C. In some embodiments, the chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr. The total exposure time of the precursor to the feature may be at least 10 seconds, for example, at least 60 seconds. As shown above, the immersion may be continuous or pulsed.

[0139] In operation 603, an initial molybdenum layer is deposited on the feature. The initial molybdenum layer can be deposited by ALD. The initial molybdenum layer is formed by depositing one or more sequential doses of molybdenum precursor and reducing agent into the deposition chamber. The molybdenum precursor is a non-oxygen-containing molybdenum precursor. The non-oxygen-containing precursor helps to prevent oxidation of the surface of the feature and ensures that the contact resistance remains low. The non-oxygen-containing molybdenum precursor may be a molybdenum-containing halide compound. An example of the non-oxygen-containing precursor is the MoCl x precursor described above. In some embodiments, the precursor can be the same in operations 602 and 603. Examples of reducing agents are given above in operation 403 of FIG. 4. The initial molybdenum layer can be selectively deposited on the feature over the metal nitride layer. Molybdenum is deposited such that the molybdenum layer forms the bottom surface of the feature. The conformal molybdenum layer may be 1 to 5 nm in some embodiments. In some embodiments, the conformal molybdenum layer has a thickness of 2 nm or less.

[0140] In the deposition operation of 603, the temperature of the substrate, the pressure of the chamber in the semiconductor processing tool, and the exposure time of the precursor to the feature can be controlled. In some embodiments, the substrate can be heated at 350°C to 700°C, for example, 375°C to 475°C. In some embodiments, the chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr. The total exposure time of the precursor to the feature may be at least 10 seconds, for example, at least 60 seconds. As shown above, the immersion can be continuous or pulsed. In some embodiments, the temperature of the substrate during operation 603 is higher than the temperature of the substrate during operation 602, for example, at least 50°C, at least 100°C, at least 200°C. In some embodiments, the temperature of the substrate remains the same between operation 602 and operation 603. After the molybdenum layer is deposited, the molybdenum layer and the underlying metal nitride layer are removed from at least a portion of the sidewall of the feature. Operation 605 may involve performing an etching operation similar to that described above with respect to operation 602. The etching is performed such that the metal nitride layer and the molybdenum layer on the bottom surface remain in the feature. The metal nitride layer and the molybdenum layer on the bottom surface of the feature can be used to protect the active bond on the bottom of the feature. In the etching, it is possible to use the same precursor or a different precursor as described in the etching operation described above in operation 602. The etching in operation 605 can be "more aggressive" than the cleaning and / or etching performed in operation 602. The more aggressive etching in operation 605 can be performed at a higher temperature, a higher pressure, a longer exposure time of the precursor, or a combination thereof than in operation 602.

[0141] After the metal nitride layer and the molybdenum layer are removed from the sidewalls of the feature in operation 605, in operation 607, the feature is filled with molybdenum. The feature can be filled by using ALD or CVD, including thermal and plasma enhanced ALD and CVD processes. Molybdenum halide or oxyhalomolybdenum can be used as a precursor for the filling operation. In some embodiments, multiple precursors can be used to fill the feature. In one such embodiment, a molybdenum halide precursor can be used to deposit molybdenum onto the feature, and then an oxyhalomolybdenum precursor can be used for bulk molybdenum filling. For example, the feature can be first filled using MoCl 5 as a precursor, and then filled using MoO 2 Cl 2 . Examples of molybdenum halide precursors and oxyhalomolybdenum precursors have been described above. Feature filling can be non-selective or selective according to various embodiments. In some embodiments, feature filling can be selective to partially fill the feature, and then more conformal filling can be performed to complete the feature filling.

[0142] The filling process can use the same parameters as described above in FIG. 5. Similar to the operation of 503, the substrate can be heated at 300°C to 500°C, for example, 350°C to 450°C. The chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr. The exposure time of the reactant can be at least 5 seconds, for example, at least 15 seconds. In some embodiments, process parameters such as temperature can be used to control selectivity.

[0143] FIG. 7 is a process flow diagram showing a method of filling a feature having a nitride feature with a molybdenum (Mo) film. The nitride feature may be a nitride plug or a nitride layer at the bottom of the feature. Method 700 begins at operation 701 with providing a substrate having a metal nitride feature. The substrate may be provided to a semiconductor processing tool.

[0144] The feature generally has two sidewall surfaces that intersect at the bottom of the feature. The two sidewall surfaces are generally inclined such that the feature is in a "V shape". The feature may be formed in a dielectric layer as a trench or via and is connected to the underlying layer. Examples of materials forming the bottom and sidewalls are given above with reference to operation 401 of FIG. 4.

[0145] In some embodiments, the nitride feature may be a nitride plug. In some embodiments, the nitride plug is a metal nitride plug. The nitride plug is at the bottom of the feature. In some embodiments, the metal nitride feature may be a metal nitride layer. In some embodiments, the metal nitride layer can conformally line the feature such that the sidewall surfaces are the metal nitride layer. In some embodiments, the metal nitride layer may line a portion of the sidewall such that the bottom portion of the sidewall surface is the metal nitride layer and the upper portion of the sidewall surface is a dielectric material. Examples of metal nitrides are TiN and TiSiN.

[0146] In some embodiments, the sidewall surfaces are oxidized. Oxidation may be caused by exposing the surface of the feature to air or other oxidizing conditions. In some embodiments, oxidizing conditions occur during the processing or transfer operations of the substrate. In some embodiments, intentional oxidation is performed as described above with reference to FIG. 5.

[0147] After providing a substrate having a metal nitride feature, in operation 702, optional cleaning and / or optional etching can be performed. Cleaning can be used to remove oxides from the field and feature surfaces, while optional etching can be used to remove a portion of the metal nitride layer on the sidewalls or field of the substrate. An example of the cleaning process is given above in operation 502 of FIG. 5. After optional etching, the metal nitride surface is at the bottom portion of the feature.

[0148] When performed, operation 702 can involve immersing the feature in a molybdenum precursor to remove oxidation and / or removing or reducing the metal nitride layer from the feature. In some embodiments, etching can result in more material being etched in the upper portion compared to the bottom of the feature. In a first example, the metal nitride layer can conformally line the feature. By etching, the metal nitride layer in the upper portion of the feature can be removed, leaving the metal nitride layer in the bottom portion of the feature. In this example, the upper portion of the sidewall surface can be a dielectric material or the upper portion of the sidewall surface can be a metal nitride layer. As described above in operation 602, the precursor gas can be continuously immersed, pulsed, or circulated with another gas such as a purge gas. In some embodiments, the precursor gas can be a molybdenum-containing halide precursor. For example, the precursor gas can be MoCl x It may be. MoCl x Examples of precursors are given above. In some embodiments, the etching can be net etching as described above. In this example, net etching is molybdenum chloride in H 2It can react with reactants such as etc. Molybdenum is deposited at the bottom of the feature, and at the same time, molybdenum chloride can etch and remove a part of the metal nitride liner at the top of the feature. In the cleaning / etching operation of 602, the temperature of the substrate, the pressure of the chamber in the semiconductor processing tool, and the exposure time of the precursor to the feature can be controlled. These process controls are the same as the process controls described in operation 602.

[0149] As described above in operation 602, in the case of ALD, the temperature of the substrate and the pressure of the chamber can be controlled. Using these process parameters, the selectivity can be controlled so that the initial molybdenum layer is first deposited on the metal nitride surface on the bottom portion of the feature. In some embodiments, the substrate can be heated at 300 °C to 500 °C, for example, 350 °C to 450 °C. In some embodiments, the chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr.

[0150] In operation 703, the initial molybdenum layer is selectively deposited on the metal nitride feature at the bottom portion of the feature. In embodiments where the feature has a metal nitride layer, molybdenum is deposited on the metal nitride layer at the bottom portion of the side wall surface at the bottom portion of the feature. In embodiments where the feature has a metal nitride plug, molybdenum is deposited on the metal nitride plug at the bottom of the feature. The initial molybdenum layer can grow upward from the metal nitride surface at the bottom of the feature. Molybdenum can be deposited by ALD, plasma-enhanced ALD, CVD, or plasma-enhanced CVD using a molybdenum halide precursor and a reactant. The molybdenum halide precursor may be a molybdenum chloride compound such as MoCl 5 etc., and the reactant may be H 2 etc. Examples of additional precursors and reactants are listed above.

[0151] As described above in operation 603, in the case of ALD, the temperature of the substrate and the pressure of the chamber can be controlled. Using these process parameters, the selectivity can be controlled such that the initial molybdenum layer is first deposited on the metal nitride surface on the bottom portion of the feature. In some embodiments, the substrate can be heated at 350 °C to 700 °C, for example, 375 °C to 475 °C. In some embodiments, the chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr. In some embodiments, the temperature of the substrate during operation 703 is higher than the temperature of the substrate during operation 702, for example, at least 50 °C, at least 100 °C. In some embodiments, the temperature of the substrate remains the same between operation 602 and operation 603.

[0152] After the initial molybdenum layer is deposited, in operation 705, the feature is filled with molybdenum. The molybdenum fill is deposited on the initial molybdenum layer deposited in operation 703. The filling can be performed using the same molybdenum halide precursor used in the previous operation, or can be filled using a molybdenum oxyhalide precursor. The precursor can be deposited using a reactant such as H 2 and the like. The feature can be filled using ALD, plasma enhanced ALD, CVD, or plasma enhanced CVD.

[0153] Figures 8A-8D show schematic examples of the process of FIG. 7. FIG. 8A shows a feature 801 formed in a dielectric material 803. The feature 801 has a metal nitride layer 805 conformally deposited on the feature 801. In some embodiments, the metal nitride layer 805 is a TiN layer. The metal nitride layer forms two sidewall surfaces 807. The feature 801 is a V-shaped trench and has sidewall surfaces 807 that converge at the bottom portion 813 of the feature.

[0154] FIG. 8B shows the feature 801 after undergoing the cleaning and etching operations as described above in operation 702 of FIG. 7. The feature effectively removes the oxide MoCl xIt is immersed using a precursor. The immersion also removes the upper portion of the metal nitride layer 805, such that the metal nitride layer 805 remains at the bottom portion 813 of the feature 801. After the cleaning operation, each of the side wall surfaces 807 has the metal nitride layer 805 on the bottom portion side wall surface and has the dielectric material 803 on the upper portion of each of the side wall surfaces.

[0155] FIG. 8C illustrates the feature 801 after the initial molybdenum film 809 has been deposited on the feature 801 as described above in operation 703 of FIG. 7. The initial molybdenum film 809 is selectively deposited such that the initial molybdenum layer is deposited on the surface of the metal nitride layer 805 at the bottom portion 813 of the feature 801. The initial molybdenum film 809 is deposited minimally or not at all on the dielectric material 803, forming the side wall surface 807 on the upper portion of the feature 801. Thus, the molybdenum film 809 is deposited and fills from the bottom portion 813 of the feature 801.

[0156] FIG. 8D shows the feature 801 after the feature has been filled with molybdenum 815 as described in operation 705 of FIG. 7. The molybdenum fill is deposited on the initial molybdenum layer shown in FIG. 8C and grows from the bottom portion 813 of the feature until the feature is filled with Mo. The feature can be filled using ALD, plasma enhanced ALD, CVD, or plasma enhanced CVD. In some embodiments, the fill uses a molybdenum oxyhalide precursor such as MoO 2 Cl 2 and so on. In some embodiments, the fill uses a molybdenum halide precursor such as MoCl 5 and so on.

[0157] FIGS. 9A-9D show a schematic example of the process of FIG. 7. FIG. 9A shows a feature 901 formed in a dielectric material 903. The feature 901 has side wall surfaces 907 and a bottom surface 908. The feature 901 has a metal nitride layer 905 deposited conformally to the feature 901. In some embodiments, the metal nitride layer 905 is a TiN layer. The metal nitride layer forms the two side wall surfaces 907 and the bottom surface 908.

[0158] Figure 9B shows feature 901 after undergoing the cleaning and etching operations as described above in operation 702 of FIG. 7. The feature is immersed using an MoCl x precursor that effectively removes the oxide. The immersion also removes the upper portion of the metal nitride layer 905 such that the metal nitride layer 905 remains at the bottom portion 913 of the feature 901. After the cleaning operation, each of the sidewall surfaces 907 has a metal nitride layer 905 on the bottom portion sidewall surface and a dielectric material 903 on the upper portion of each of the sidewall surfaces. The metal nitride layer 905 remains the bottom surface 908 of the feature 901.

[0159] Figure 9C illustrates feature 901 after the initial molybdenum film 909 has been deposited on feature 901 as described above in operation 703 of FIG. 7. The initial molybdenum film 909 is selectively deposited such that the initial molybdenum layer is deposited on the surface of the metal nitride layer 905, i.e., on the sidewall surfaces 907 and the bottom surface 908 at the bottom portion 913 of the feature 901. The initial molybdenum film 909 is deposited minimally or not at all on the dielectric material 903 and forms the sidewall surfaces 907 on the upper portion of the feature 901. Thus, the molybdenum film 909 is deposited and fills from the bottom portion 913 of the feature 901.

[0160] Figure 9D shows feature 901 after the feature has been filled with molybdenum 915 as described in operation 705 of FIG. 7. The molybdenum fill is deposited on the initial molybdenum layer shown in FIG. 9C and grows from the bottom portion 913 of the feature until the feature is filled with Mo. The feature can be filled using ALD, plasma-enhanced ALD, CVD, or plasma-enhanced CVD. In some embodiments, the fill uses a molybdenum oxyhalide precursor such as MoO 2 Cl 2 . In some embodiments, the fill uses a molybdenum halide precursor such as MoCl 5 .

[0161] Figures 10A - 10C show a second schematic example of the process of FIG. 7. FIG. 10A shows a feature 1001 formed in a dielectric material 1003. The feature 1001 is a V - shaped trench and has sidewall surfaces 1007 that converge at the bottom portion 1013 of the feature. The sidewall surfaces 1007 are the dielectric material 1003. The feature 1001 has a metal nitride plug 1011 at the bottom portion 1013 of the feature 1001. In some embodiments, the metal nitride plug 1011 is a TiN plug.

[0162] FIG. 10B illustrates the feature 1001 after an initial molybdenum layer 1009 has been deposited on the feature 1001 as described above in operation 703 of FIG. 7. The initial molybdenum layer 1009 is selectively deposited on the metal nitride plug 1011 at the bottom portion 1013 of the feature 1001. Similar to the schematic of FIG. 8C, the initial molybdenum layer 1009 is hardly or not at all deposited on the sidewall surfaces 1007 of the dielectric material 1003.

[0163] FIG. 10C shows the feature 1001 after the feature has been filled with molybdenum 1015 as described in operation 705 of FIG. 7. The molybdenum fill is deposited on the initial molybdenum layer. The feature 1001 is filled from the bottom portion 1013 of the feature and grows upward. The feature can be filled using ALD, plasma - enhanced ALD, CVD, or plasma - enhanced CVD. In some embodiments, the fill uses a molybdenum oxyhalide precursor such as MoO 2 Cl 2 and in some embodiments, the fill uses a molybdenum halide precursor such as MoCl 5 etc.

[0164] FIG. 11 is a process flow diagram showing a method of filling a feature having no metal surface with a molybdenum film. The method 1100 begins in operation 1101 with providing a substrate having no metal surface. The substrate may be provided to a semiconductor processing tool.

[0165] The feature generally has an opening with two sidewall surfaces that intersect at the bottom of the feature. The feature bottom may be referred to as a closed end. The two sidewall surfaces generally slope such that the feature is V-shaped. The feature may be formed in a dielectric layer as a trench or via and is connected to a lower layer. Examples of dielectric materials forming the bottom and sidewalls are given above.

[0166] In operation 1103, a molybdenum plug is formed in the bottom portion of the feature. As described above, the molybdenum plug can be formed by depositing a molybdenum-containing halide precursor and a reactant. The molybdenum-containing halide precursor may be a molybdenum chloride precursor such as MoCl 5 etc. Using the method described above, H 2 can be used as a reactant. The molybdenum plug can be formed at the bottom of the feature when deposition is performed using (i) a high ratio of molybdenum chloride precursor to the H 2 reactant, (ii) a relatively high process pressure during deposition, or (iii) a combination thereof. In some embodiments, the substrate temperature for plug formation may be less than 450 °C.

[0167] In operation 1105, an initial molybdenum layer is selectively deposited on the molybdenum plug in the bottom portion of the feature. The process parameters are controlled such that the initial molybdenum layer is deposited on the molybdenum plug at the bottom of the feature. The initial molybdenum layer can be deposited by ALD, plasma-enhanced ALD, CVD, or plasma-enhanced CVD using a molybdenum-containing halide precursor and a reactant. The molybdenum-containing halide precursor may be a molybdenum chloride precursor such as MoCl 5 etc. The reactant may be, for example, H 2 Examples of additional precursors and reactants are listed above.

[0168] As described above in operation 603, in the case of ALD, the temperature of the substrate and the pressure of the chamber can be controlled. Using these process parameters, the selectivity can be controlled such that the initial molybdenum layer is first deposited on the metal nitride surface on the bottom portion of the feature. In some embodiments, the substrate can be heated at 300 °C to 500 °C, for example, 350 °C to 450 °C. In some embodiments, the chamber can be pressurized to at least 10 Torr, for example, at least 30 Torr, or at least 50 Torr.

[0169] After the initial molybdenum layer is deposited on the molybdenum plug, in operation 1107, the feature is filled with molybdenum. The molybdenum fill is deposited on the initial molybdenum layer deposited in the previous operation. The filling can be performed using the same molybdenum halide precursor used in the previous operation, or can be filled using a molybdenum oxyhalide precursor during the operation. The precursor can be deposited using a reactant such as H 2 and the like. The feature can be filled using ALD, plasma enhanced ALD, chemical vapor deposition (CVD), or plasma enhanced CVD.

[0170] In some embodiments, the feature is filled using a molybdenum plug without a metal nitride layer. FIGS. 12A to 12C show schematic examples of such a process. FIG. 12A shows a feature 1201 formed in a dielectric material 1203. The feature 1201 has a metal layer 1205 conformally deposited on the feature 1201. The feature 1201 also has a metal plug 1211. The metal can be, for example, Mo. The metal layer forms two side wall surfaces 1207. The feature 1201 is a V-shaped trench and has side wall surfaces 1207 that converge at the bottom portion 1213 of the feature.

[0171] FIG. 12B shows the feature 1201 after undergoing an etching operation. The feature is etched using a molybdenum-containing precursor. Examples include MoCl 5 and MoOCl 4Examples include. By etching, the upper portion of the metal layer 1205 is removed so that the metal layer 1205 remains at the bottom portion 1213 of the feature 1201. After etching, each of the sidewall surfaces 1207 has a dielectric material 1203 on the upper portion of each of the sidewall surfaces. The metal plug 1211 remains within the feature. In some embodiments, the metal layer 1205 may be on the lower portion of the sidewall surface 1207.

[0172] FIG. 12C shows the feature 1201 after the feature is filled with Mo 1215. The initial Mo film is selectively deposited on the metal plug 1211. The Mo fill is deposited on the metal plug 1211 shown in FIG. 12B and grows from the bottom portion 1213 of the feature until the feature is filled with Mo. The feature can be filled using ALD, plasma-enhanced ALD, CVD, or plasma-enhanced CVD. In some embodiments, the fill uses a molybdenum oxyhalide precursor such as 2 Cl 2 . In some embodiments, the fill uses a molybdenum halide precursor such as MoCl 5 .

[0173] In some embodiments, one or more of the following techniques can be used to reduce resistivity. The first technique is to use a high flow rate to flow a gas into the chamber. The high flow rate may be from about 5 slm to about 60 slm, for example, from about 10 slm to 50 slm. In one example, a high flow rate can be used to flow H 2 gas into the chamber. In another example, a high flow rate can be used to flow a purge gas such as Ar into the chamber.

[0174] The second technique is to use a plurality of H 2 pulses as reactants. In film deposition, after the precursor flows into the chamber, H 2 can be used as a reactant. In some embodiments, H 2Multiple pulses of gas can be used to react with the precursor. For example, the precursor gas is flowed into the chamber, followed by H 2 Two or more pulses of reactant are used. In some embodiments, H 2 can be pulsed sequentially. In some embodiments, this sequence is H 2 gas flowed into the chamber following a purge operation, followed by H 2 a second flow of H gas can be flowed into the chamber. In some embodiments, H 2 the gas flow, purge operation sequence can be continued two or more times.

[0175] A third technique is to use a charge volume. The charge volume can be used to increase the mass flow rate of gas into the chamber. In some embodiments, multiple charge volumes may be used. By using multiple charge volumes, the mass flow rate of the gas can increase as the gas enters the chamber. In some embodiments, multiple charge volumes can be used to maintain a higher mass flow rate into the chamber. In some embodiments, the charge volume can be used to flow a reactant such as H 2 into the chamber. In some embodiments, the charge volume can be used to flow a purge gas. By flowing a purge gas into the chamber using the charge volume, the chamber can be purged more quickly.

[0176]

[0177] Exemplary sequences that can be used to reduce resistivity are shown in FIG. 13. In the illustrated sequences, a molybdenum-containing precursor is first flowed into the chamber. Examples of molybdenum-containing precursors are given above. Following the flow of the molybdenum-containing precursor, a purge operation is performed. Following the purge, the pressure in the chamber is pumped down to a lower pressure. After the chamber pressure has been pumped down, hydrogen is flowed into the chamber. After the hydrogen, a purge operation is performed and then the chamber pressure is pumped down. As described above, the chamber pressure is reduced by pumping down the chamber pressure. The mini-cycle of flowing hydrogen and the subsequent purge operation and pumping down of the chamber pressure can be repeated multiple times. In some embodiments, the mini-cycle may be circulated two or more times. In the sequence shown in FIG. 13, the mini-cycle of flowing hydrogen and the subsequent purge operation and pumping down of the chamber pressure are circulated three times.

[0178] In some embodiments, multiple charge amounts can be used for each purge operation. This is described in International Publication No. WO 2020 / 214732, which is incorporated herein by reference.

[0179] In some embodiments, one or more of the following techniques can be used to reduce grain boundaries. In the first technique, an inhibitor can be used on the sidewalls of the feature. During the deposition of molybdenum onto the feature, an inhibitor can be used on the sidewalls to slow or stop the growth of molybdenum on the sidewalls. The second technique is to etch or remove Mo nuclei on the sidewalls of the feature. For example, during an etching operation as described above, MoCl 5 can be used to etch Mo nuclei on the sidewalls of the feature. In another example, molybdenum oxytetrachloride (MoOCl 4Using , it is possible to etch the Mo nuclei on the sidewalls. An exemplary process can include the deposition of molybdenum onto the feature. In the initial deposition of molybdenum, Mo nuclei can be deposited on the sidewalls of the feature. After the deposition, an etching operation may follow. In an exemplary etching operation, MoCl 5 can be used for etching. The etching can remove a portion of the Mo deposited on the feature that includes any Mo nuclei deposited on the sidewalls. After the etching, deposition may be performed. The deposition may include depositing Mo. The deposition may be a bottom-up fill that deposits Mo on top of the molybdenum in the feature that was not etched away in the previous operation

[0180] In a 3D NAND structure, the processing of lateral features such as word lines can be used to improve the fill within the structure. The processing can include nucleation inhibition, etching, or combinations thereof. Nucleation inhibition inhibits subsequent Mo nucleation on the processed surface. This can involve one or more of the deposition of an inhibitor film, the reaction of a process species for forming a compound film (e.g., Mo 2 N) with the Mo film, and the adsorption of inhibitor species. During subsequent deposition operations, there is a delay in nucleation in the inhibited portions of the underlying film compared to the portions that are not inhibited or are not as inhibited. As shown in FIG. 14A, the inhibitor non-conformally processes the feature. The amount of inhibitor 1403 increases towards the outside of the feature and decreases towards the inside of the feature. A greater amount of unprocessed Mo film 1405 is inside the feature. In the example shown, the Mo film 1405 can be deposited in the inner portion of the feature. In subsequent depositions, the deposited Mo can be deposited on the Mo within the feature while the inhibitor reduces or delays the growth of Mo. Examples of inhibitors include ammonia (NH 3 ), oxygen (O 2 ), nitrogen (N 2 ), H 2 , methane (CH 4 ), hydrazine (N 2 H4 ), nitrogen trifluoride (NF 3 ), SiH 4 , B 2 H 6 , and their derivatives

[0181] By etching, the deposited film on the processed surface is removed. This may involve reacting the etchant species with the molybdenum film to form gaseous by-products and then removing them. Other methods of etching, including atomic layer etching, may be implemented. The etching operation may be a plasma operation or a non-plasma operation. In the case of a non-plasma operation, the etching operation may be purely thermal or activated by some other energy such as UV.

[0182] Nitrogen acts as an inhibitor species, and halogen (e.g., fluorine and chlorine) species act as etchants. To perform a pure inhibition treatment, one example involves treating the feature with a nitrogen-containing chemical substance that does not contain halogen. To perform a pure etching treatment, the treatment involves exposing the Mo film to a halogen-containing chemical substance that does not contain nitrogen. Other inhibitor chemicals (e.g., oxygen-containing chemicals) may be used in some embodiments. Exposing the film to both a nitrogen-containing chemical substance and a halogen-containing chemical substance (e.g., nitrogen trifluoride (NF 3 )) or ammonia / fluorine (NH 3 / F 2 )) allows for both inhibition and etching.

[0183] FIG. 14B shows a feature after a deposition, etching, deposition sequence. Using a conformal ALD process, Mo can be deposited onto the feature. As shown, Mo is conformally deposited around each of the features uniformly from the outside (slit side) to the inside (non-slit side). Following the deposition, an etching operation may be performed. The etching can be performed non-conformally to remove more of the Mo film on the outer portion of the word line. In the outer portion of the word line, the oxide of the feature may be exposed. The inner portion of the word line may be etched less so that Mo remains on the inner feature. After the illustrated etching operation, a second deposition operation can be performed. The deposition can be selective with respect to the Mo film remaining on the film. Thus, the film deposited in the subsequent deposition can be selectively deposited on the inner portion of the word line. When Mo begins to grow, the deposition can become conformal. As shown, after the subsequent deposition, the Mo film may be thicker on the inner portion of the feature compared to the outer portion of the feature.

Claims

1. (a) providing a substrate comprising a feature having an opening and sidewalls, wherein a metal nitride layer lines the sidewalls of the feature; and (b) at least partially etching the metal nitride layer along the sidewalls of the feature using a molybdenum-containing halide compound, leaving a first portion of the metal nitride layer on the feature; and (c) selectively depositing molybdenum on the first portion of the metal nitride layer in the feature by reacting the molybdenum-containing halide compound with a first reactant after at least partially etching the metal nitride layer; A method comprising the above steps.

2. The method according to claim 1, wherein (b) comprises removing metal nitride from a portion of the sidewalls, exposing the portion of the sidewalls of the feature.

3. The method according to claim 1, wherein the feature has a feature bottom, and after (d) and (c), further comprising at least partially etching the first portion of the metal nitride layer and the molybdenum using the molybdenum-containing halide compound, leaving a second portion of the metal nitride layer and the remaining molybdenum on the feature bottom.

4. The method according to claim 1 or 3, further comprising (e) filling the feature with molybdenum.

5. The method according to claim 1, wherein the molybdenum-containing halide compound is a molybdenum chloride compound.

6. The method according to claim 1, wherein the molybdenum-containing halide compound is molybdenum pentachloride.

7. The method according to claim 4, wherein (e) comprises reacting a second molybdenum-containing halide compound with a second reactant.

8. The method according to claim 4, wherein (e) comprises reacting a molybdenum-containing oxyhalide precursor with a second reactant.

9. The method according to claim 1, wherein the metal nitride layer conformally lines the feature.

10. The method according to claim 1, wherein The method of (b) further includes reacting the molybdenum-containing halide compound with the first reactant to deposit molybdenum on the feature during the etching.

11. The method according to claim 1, wherein the first reactant is a hydrogen-containing reactant.

12. The method according to claim 1, The first reactant is hydrogen (H 2 ).

13. The method according to claim 1, wherein (b) is carried out at a first substrate temperature, wherein (c) is carried out at a second substrate temperature, and the second substrate temperature is higher than the first substrate temperature. Method.

14. (a) providing a substrate having a feature with an opening, a closed end, and sidewalls; (b) forming a molybdenum plug on the closed end of the feature by reacting a molybdenum-containing halide compound with a first reactant; and (c) selectively depositing molybdenum on the molybdenum plug by reacting the molybdenum-containing halide compound with the first reactant. Method.

15. The method according to claim 14, wherein the sidewalls are inclined and intersect at the closed end of the feature.

16. The method according to claim 14, further including filling the feature with molybdenum after (d) and (c).

17. The method according to claim 16, wherein (d) includes reacting a second molybdenum-containing halide compound with a second reactant.

18. The method according to claim 16, wherein (d) includes reacting a molybdenum-containing oxyhalide compound with a second reactant.

19. The method according to claim 14, wherein the molybdenum-containing halide compound is a molybdenum chloride compound.

20. The method according to claim 14, wherein the molybdenum-containing halide compound is molybdenum pentachloride.

21. The method according to claim 14, wherein the first reactant is a hydrogen-containing reactant.

22. The method according to claim 14, The first reactant is hydrogen (H 2 ). Method.

23. The method according to claim 14, wherein (b) is carried out at a substrate temperature of less than 450 °C.

24. (a) providing a substrate having a feature with a metal nitride plug; (b) selectively depositing molybdenum on the metal nitride plug in the feature by reacting a molybdenum-containing halide compound with a first reactant A method comprising the above. **Claim 25** The method according to claim 24, further comprising cleaning the feature using the molybdenum-containing halide compound between (a) and (b). **Claim 26** The method according to claim 24, further comprising filling the feature with molybdenum after (c) and (b). **Claim 27** The method according to claim 24 or 25, wherein the molybdenum-containing halide compound is a molybdenum chloride compound. **Claim 28** The method according to claim 24 or 25, wherein the molybdenum-containing halide compound is molybdenum pentachloride. **Claim 29** The method according to claim 24, wherein the first reactant is a hydrogen-containing reactant. **Claim 30** The method according to claim 26, wherein filling the feature with molybdenum includes reacting a second molybdenum-containing halide precursor with a second reactant. **Claim 31** The method according to claim 26, wherein filling the feature with molybdenum includes reacting a molybdenum-containing oxyhalide precursor with a second reactant.

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