Molybdenum halides in memory applications

Abstract

Processes for filling features with the methods are provided. The treatment includes deposition, etching, and cleaning operations using a molybdenum chloride (MoClx) compound. The MoClx compound may be controlled to selectively deposit on the metal nitride features, form plugs and crystals on the dielectric material, and perform a net etch of the material within the features as compared to the dielectric. In-situ cleaning treatments are also provided in which the oxides of the underlying surface are removed prior to deposition using a MoClx compound. Subsequent deposition using the MoClx precursor may deposit an initial layer and / or fill features.

Description

Incorporated by Reference

[0001] The PCT application form is filed concurrently with this specification as a part of this application. Each application identified in the concurrently filed PCT application form to which this application claims the benefit or priority is incorporated herein by reference in its entirety and for all purposes. Background Art

[0002] The deposition of materials, including tungsten-containing materials, is an integral part of many semiconductor manufacturing processes. These materials can be used for horizontal interconnects, vias between adjacent metal layers, contacts between metal layers and devices, and as wires in memory devices. In an example of deposition, a tungsten (W) layer can be deposited on a titanium nitride (TiN) barrier layer using tungsten hexafluoride (WF6) by CVD processing to form a TiN / W double layer. However, as device sizes shrink and more complex patterning schemes are used in the industry, the deposition of tungsten thin films becomes a challenge. The continued reduction in feature size and film thickness has brought various challenges to TiN / W film stacks. These include high resistivity of thinner films and the decline in TiN barrier properties. Deposition in complex high aspect ratio structures (such as 3D NAND structures) is particularly challenging.

[0003] The background description provided here is for the purpose of generally presenting the context of the present disclosure. The work of the presently designated inventors is neither explicitly nor implicitly admitted to be prior art against the present disclosure to the extent that it is described in this background section and to aspects of the specification that could not be determined as prior art at the time of filing the application. 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 a sidewall, wherein a metal nitride layer lines the sidewall of the feature; (b) at least partially etching the metal nitride layer along the sidewall of the feature using a molybdenum-containing halide compound to leave a first portion of the metal nitride layer in the feature; and (c) after at least partially etching the metal nitride layer, 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.

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

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

[0007] In some embodiments, it further comprises (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, wherein (e) comprises reacting a second molybdenum-containing halide compound with a second reactant.

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

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

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

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

[0015] In some embodiments, the first reactant is hydrogen (H2).

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

[0017] One aspect of the present disclosure relates to a method comprising: (a) providing a substrate comprising a feature, the feature including 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 sidewalls are sloped and meet at the closed end of the feature.

[0019] In some embodiments, (c) is followed by (d), filling the feature with molybdenum.

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

[0021] In some embodiments, wherein (d) comprises 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, wherein the first reactant is a hydrogen-containing reactant.

[0025] In some embodiments, the first reactant is hydrogen (H2).

[0026] In some embodiments, wherein (b) is performed at a substrate temperature below 450°C.

[0027] One aspect of the present disclosure relates to a method comprising: (a) providing a substrate including a feature having a metal nitride plug; and (b) 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, between (a) and (b) further comprises, cleaning the feature with the molybdenum-containing halide compound.

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

[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, wherein the first reactant is a hydrogen-containing reactant.

[0033] In some embodiments, the first reactant is hydrogen (H2).

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

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

[0036] Figure 1A and 1B is a schematic illustration of a material stack including molybdenum (Mo) according to various embodiments.

[0037] Figure 2A-2L are illustrative examples of various structures into which molybdenum may be deposited according to the disclosed embodiments.

[0038] Figure 3-7 is a flow chart illustrating certain operations in a method according to various embodiments.

[0039] Figures 8A-10C is a schematic diagram showing a cross-sectional depiction of a feature during a fill process according to various embodiments.

[0040] Fig.11 is a flow chart illustrating a method of filling a feature by forming a molybdenum plug according to various embodiments.

[0041] Figures 12A-12C is a schematic diagram showing a cross-sectional depiction of a feature filled with a molybdenum plug without a metal nitride layer according to various embodiments.

[0042] Fig.13 A sequence for reducing resistivity is shown according to various embodiments.

[0043] Fig.14A is an illustration of an inhibitor of a non-conformally processed feature according to various embodiments.

[0044] Fig. 14B is an illustration of a feature after a deposit, etch, deposit sequence according to various embodiments. DETAILED DESCRIPTION

[0045] In the following description, numerous specific details are set forth to provide a full understanding of the embodiments presented. The disclosed embodiments may be implemented without some or all of these specific details. In other examples, well-known processing operations are not described in detail to avoid unnecessarily obscuring the disclosed embodiments. Although the disclosed embodiments will be described in conjunction with specific embodiments, it should be understood that they are not intended to limit the disclosed embodiments.

[0046] Methods for filling features with molybdenum (referred to herein as Mo) are provided herein, which can be used in logic and memory applications. Mo has many advantages over other metals such as cobalt (Co), ruthenium (Ru), and tungsten (W): (i) barrier-free and liner-free Mo film deposition on oxides and nitrides is more feasible than Co, Ru, and W; (ii) Mo resistivity scales better than W; (iii) below 450°C, Mo intermixing with underlying Co is not expected to occur compared to Ru and Co intermixing, and (iv) Mo is relatively easy to integrate into current W schemes compared to Co and Ru.

[0047] Figure 1A and 1B are illustrative examples of material stacks including molybdenum according to various embodiments. Figure 1A and 1BThe material order in the example of a specific stack is depicted and can be used with any suitable architecture and application, as described below with respect to Figure 2A –2L further described. Figure 1A A first material stack 111 is shown, characterized by a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 can be a silicon or other semiconductor wafer, such as a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including a wafer having one or more layers of material deposited thereon, such as a dielectric, conductive, or semiconductor material. In some embodiments, the substrate 102 can be or include silicon germanium (SiGe). The method can also be applied to form metallization stack structures on other substrates such as glass, plastic, etc.

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

[0049] Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, with specific examples including doped or undoped SiO2 and Al2O3 layers. The stack 111 has a layer 106 disposed between the molybdenum layer 108 and the dielectric layer 104. The layer 106 may be, for example, a diffusion barrier layer and / or an adhesion layer. A diffusion barrier layer is a layer that prevents substances from diffusing between layers. An adhesion layer is a layer that promotes adhesion of a layer to the underlying layer. Examples of diffusion barriers and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten (W), tungsten nitride (WN), and tungsten carbonitride (WCN). The molybdenum layer 108 is the main conductor of the structure. In some embodiments, the molybdenum layer 108 may include multiple bulk layers deposited under different conditions. The molybdenum layer 108 may or may not include a molybdenum nucleation layer. In Figure 1A In the example shown, the molybdenum layer 108 is deposited directly on the layer 106. In other embodiments (not shown), the molybdenum layer 108 can be deposited on a separate layer, such as a growth initiation layer including another material, such as tungsten (W) or a growth initiation layer containing W. The growth initiation layer can be used to promote nucleation and growth of the molybdenum layer 108.

[0050] Figure 1B Another example of a stack 121 is shown. In this example, the stack 121 includes a substrate 102, a dielectric layer 104, wherein a molybdenum layer 108 is deposited directly on the dielectric layer 104 without an intervening diffusion barrier layer or adhesion layer. The molybdenum layer 108 is as shown in FIG. Figure 1ABy using molybdenum as the primary conductor, a low resistivity film can be obtained. Examples of low resistivity films include films with a resistivity of less than 40 μOhm-cm at a thickness of 60 angstroms and a resistivity of less than 15 μOhm-cm at a thickness of 200 angstroms.

[0051] In some embodiments, the stack (not shown) may include a substrate, a conductive layer, and a molybdenum layer deposited onto the conductive layer. As used herein, the conductive layer is a layer having a relative humidity of at least 10 4 Ω -1 -cm -1 The stack may include a layer of a conductive layer having a conductivity of 100%. 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 may include molybdenum deposited directly on a metal compound layer. Examples include molybdenum on a metal nitride layer (e.g., TiN, WN, or MoN). In still other embodiments of the stack (not shown), the stack may include a substrate and a molybdenum layer deposited directly on the substrate, including directly deposited on a semiconductor surface, a dielectric surface, or a conductive surface. Figure 1A and 1B Examples of material sequences in a particular stack are shown and may be used with any suitable architecture and application, as described below with reference to Figures 2A-2J Further described.

[0052] The methods described herein are performed on a substrate that can be contained in a chamber. The substrate can be a silicon or other semiconductor wafer, including a wafer having one or more layers of material (e.g., dielectric, conductive, or semiconductor material) deposited thereon. The method is not limited to semiconductor substrates and can be performed to fill any feature with molybdenum.

[0053] The substrate may have features such as vias or contact holes characterized by one or more narrow and / or recessed openings, constrictions within the features, and high aspect ratios. The features may be formed in one or more of the above stacks or layers within the stacks. For example, the features may be at least partially formed in a dielectric layer. In some embodiments, the features may have aspect ratios 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 a substrate.

[0054] Figure 2AA schematic example of a DRAM architecture including a molybdenum (Mo) buried word line (bWL) 208 in a silicon substrate 202 is depicted. The molybdenum bWL is formed in a trench etched in the silicon substrate 202. The trench is lined with a conformal barrier 206 and an insulating layer 204. The conformal barrier 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 of a high-k dielectric material (e.g., silicon oxide or silicon nitride material). In some embodiments disclosed herein, the conformal barrier 206 is a TiN or tungsten-containing layer. In embodiments where TiN is used as a conformal barrier, a conformal tungsten-containing growth initiation layer (not shown) may be present between the conformal barrier 206 and the molybdenum bWL 208. Alternatively, the molybdenum bWL may be deposited directly on the TiN or other diffusion barrier layer. In some embodiments, one or both of the layers 204 and 206 are not present.

[0055] Figure 2A The bWL structure shown in is one example of an architecture that includes a molybdenum fill layer. During fabrication of the bWL, molybdenum is deposited into features that may be defined by etched recesses in silicon substrate 202, which is conformally lined with layers 206 and 204 (if present).

[0056] Figure 2B-2H are additional illustrative examples of various structures into which molybdenum may be deposited according to the disclosed embodiments. Figure 2B An example of a cross-sectional drawing showing a vertical feature 201 to be filled with Mo. The feature may include a feature hole 205 in a silicon substrate 202. The feature hole 205 may have a lower layer 203 that lines the sidewalls or interior of the feature hole 205 and may form an interior surface. The feature hole 205 or other features may have a size close to the opening, such as an opening diameter or line width between about 10nm and 500nm (e.g., between about 25nm and about 300nm). The feature hole 205 may be referred to as an unfilled feature or simply a feature. The vertical feature 201 and any feature may be characterized in part by an axis 218 extending through the feature length, with vertically oriented features having a vertical axis and horizontally oriented features having a horizontal axis. The lower layer 213 may be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other suitable material. Non-limiting examples of lower layers may include dielectric layers and conductive layers. Examples of dielectric materials include oxides, such as silicon oxide (SiO2) and aluminum oxide (Al2O3); 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 SiO2. In specific implementations, the lower layer can be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the lower layer does not contain tungsten. In some embodiments, the lower layer does not contain molybdenum.

[0057] In some embodiments, the feature is a wordline feature in a 3D NAND structure. For example, the substrate may include a wordline structure having any number of wordlines (e.g., 50 to 150) having at least A word line feature may be a vertical channel with a depth of 1000 m. An example of a word line feature is further described below. Another example of a feature is a trench in a substrate or layer. The feature may 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, and metal layers.

[0058] Figure 2C An example of a vertical feature 201 having a concave profile is shown. A concave 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 may taper and / or include an overhang at the feature opening. Figure 2C An example of the latter is shown, where the lower layer 213 lines the sidewalls or interior surfaces of the feature hole 105. Figure 2B Similarly, lower layer 213 may be a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other suitable material. Non-limiting examples of lower layers may include dielectric layers and conductive layers. Lower layer 213 forms protrusion 215 so that lower layer 213 is thicker near the opening of vertical feature 201 than inside vertical feature 201.

[0059] In some embodiments, a feature may be filled with one or more constrictions within the feature. Figure 2D Examples of views of various filling features with constrictions are shown. Figure 2D Each of examples (a), (b), and (c) in includes a constriction 209 at a midpoint within the feature. The width of the constriction 209 may be, for example, between about 15 nm and 20 nm. During deposition of molybdenum in a feature using conventional techniques, the constriction may cause pinching because the deposited metal blocks further deposition through the constriction before that portion of the feature is filled, resulting in a void in the feature. Example (b) also includes a protrusion 215 (e.g., a pad / blocking protrusion) at the feature opening. Such a protrusion may also be a potential pinching point. Example (c) includes a constriction 212 that is further away from the field region than the protrusion 215 in example (b).

[0060] Horizontal features such as in 3D memory structures can also be filled. Figure 2EAn example of a horizontal feature 250 is shown that includes a constriction 251. For example, the horizontal feature 250 may be a word line in a 3D NAND (also referred to as a vertical NAND or VNAND) structure. In some embodiments, the constriction may be due to the presence of a pillar or other structure in the 3D NAND. Figure 2F A cross-sectional side view of a 3D NAND structure 210 (formed on a silicon substrate 202) is presented, having a 3D NAND stack (left 225 and right 226), a central vertical structure 230, and a plurality of stacked horizontal wordline features 220 with openings 222 on reverse sidewalls 240 of the central vertical structure 230. Note that Figure 2F Two "stacks" of the illustrated 3D NAND structure 210 are shown, which together form a "groove-like" central vertical structure 230. However, in certain embodiments, there may be more than two "stacks" arranged in sequence and extending parallel to each other in space, with the gap between each pair of adjacent "stacks" forming the central vertical structure 230, such as Figure 2F In this embodiment, the horizontal word line feature 220 is a 3D memory word line feature that can fluidly enter and exit from the central vertical structure 230 through the opening 222. Although not explicitly indicated in the figure, the presence of Figure 2F The horizontal word line features 220 in both of the 3D NAND stacks 225 and 226 shown in the figure (i.e., the left 3D NAND stack 225 and the right 3D NAND stack 226) can also enter and exit the stacks from the other side of these stacks (the leftmost and rightmost sides, respectively) through similar vertical structures formed by additional 3D NAND stacks (to the leftmost and rightmost sides, but not shown). Each 3D NAND stack 225, 226 includes a stack of word line features that can fluidly enter and exit from both sides of the 3D NAND stack through a central vertical structure 230. Figure 2F In the specific example schematically shown in FIG, each 3D NAND stack includes 6 pairs of stacked word lines. However, a 3D NAND memory layout may include any number of vertically stacked word line pairs.

[0061] The wordline features in a 3D NAND stack may be formed by depositing alternating stacks of silicon oxide and silicon nitride layers, then selectively removing the nitride layers, leaving a stack of oxide layers with gaps between them. These gaps are wordline features. Any number of wordlines may be stacked vertically in such a 3D NAND structure, provided there are techniques available to form them, and techniques available to successfully achieve (substantially) gap-free fill of the vertical features. Thus, for example, a VNAND stack may include between 2 and 512 horizontal wordline features, between 8 and 128 horizontal wordline features, or between 16 and 64 horizontal wordline features, and so forth (the listed ranges being understood to include the listed endpoints).

[0062] Figure 2G Presented Figure 2F FIG. 2 is a cross-sectional top view of the same 3D NAND structure 210 shown in side view in FIG. 2 , wherein the cross section is taken through the horizontal portion 260 as shown by Figure 2F Indicated by the horizontal dashed line in . Figure 2G 1F shows several rows of pillars 255, which are shown in FIG1F as extending vertically from the bottom of substrate 202 to the top of 3D NAND structure 210. In some embodiments, pillars 255 are formed of polysilicon material and are structurally and functionally significant to 3D NAND structure 210. In some embodiments, such polysilicon pillars can be used as gate electrodes for stacked memory cells formed within the pillars. Figure 2G The top view of FIG. 2 shows that the pillar 255 forms a constriction in the opening 222 leading to the word line feature 220. The word line feature 220 extends from the central vertical structure 230 through the opening 222 (eg, Figure 2G 2 (indicated by the arrows in FIG. 2 ) is inhibited by pillars 255. In some embodiments, the horizontal gap size between adjacent polysilicon pillars is between about 1 nm and 20 nm. This reduction in fluid accessibility increases the difficulty of uniformly filling word line features 120 with material. Figure 2H , 2I 2J further illustrate the structure of word line features 220 and the challenge of uniformly filling them with molybdenum material due to the presence of pillars 255.

[0063] Figure 2H Shows something like Figure 2F FIG. 1I also schematically illustrates a vertical section through a 3D NAND structure shown in FIG. 1A , but here focusing on a single pair of wordline features 220, and additionally schematically illustrating a fill process that results in a void 275 located within the filled wordline features 220. FIG. 1I also schematically illustrates void 175, but in this figure is illustrated by a horizontal section through pillar 155, similar to FIG. Figure 2G Horizontal section shown in . Figure 2JAn accumulation of molybdenum material around the post 255 forming the constriction is shown, which results in pinching of the opening 222 so that no additional molybdenum material can be deposited in the area of ​​the void 275. Figure 2H and 2I As is apparent, void-free molybdenum filling relies on a sufficient amount of the deposited precursor migrating downward through the central vertical structure 230, through the opening 222, over the shrinking pillar 255, and into the furthest extent of the wordline feature 220, prior to cumulative deposition of molybdenum around the pillar 255, causing pinching of the opening 222 and preventing further migration of the precursor into the wordline feature 220. Similarly, Figure 2J A single word line feature 220 is shown viewed in cross-section from above, and illustrates how the substantially conformal deposition of the molybdenum material begins to pinch off the interior of the word line feature 220 due to the fact that the large width of the pillar 255 acts to partially block, and / or narrow, and / or compress what would otherwise be an open path through the word line feature 220. (Note that Figure 2J The example in can be understood as Fig.2I A 2D representation of the 3D features of the column constriction structure shown, showing the constriction as seen in plan view rather than in cross-section.

[0064] Three-dimensional structures may require longer and / or more focused exposure to the precursor to allow the innermost and bottommost regions to be filled in. Three-dimensional structures can be particularly challenging when using molybdenum halide and / or molybdenum oxyhalide precursors because they are easy to etch, and longer and more focused exposures allow for more etching as part of the structure.

[0065] Figure 2K and 2L An example showing an asymmetric trench structure DRAM bWL. Some filling processes used for DRAM bWL trenches may deform the trench, resulting in significantly non-uniform final trench width and resistance Rs. Figure 2KAn unfilled feature 261 and a filled feature 265 that exhibits line bending after filling are shown. In this example, the feature is a narrow asymmetric trench structure DRAMbWL. As shown, a plurality of features 283 are depicted on a substrate. These features 283 are spaced apart, and in some embodiments, adjacent features have a pitch between about 20 nm to about 60 nm or between about 20 nm to about 40 nm. The pitch is defined as the distance between the center axis of a feature and the center axis of an adjacent feature. The unfilled feature 261 may be generally V-shaped, as shown in feature 283, with sloping sidewalls, wherein the width of the feature narrows from the top of the feature to the bottom of the feature. These features widen from the feature bottom 273b to the feature top 273a. After some filling operations, line bending may be observed within the filled feature 265. Without being bound by a particular theory, it is believed that the cohesive forces between the opposing surfaces of the trench pull the sides of the trench together, as shown by arrows 267. This phenomenon occurs in Figure 2L 283 is shown, and can be described as "zipping up" the feature. As feature 283 is filled, more force is applied from the central axis 299 of feature 283, causing line bending. For example, molybdenum can be deposited on the sidewalls of feature 283. The deposited molybdenum 284a and 284b on the sidewalls of feature 283 thus interact closely, where the molybdenum-molybdenum bond radius r is small, thereby generating cohesive interatomic forces between the smooth growth surfaces of the molybdenum and pulling the sidewalls together, causing line bending. Described below is a method of filling features to reduce line bending.

[0066] Methods for filling features with molybdenum are provided below. The methods described herein include deposition, etching, and cleaning operations that can be used to fill substrate features, such as those described above. As described above, molybdenum has many advantages over other metals (e.g., cobalt (Co), ruthenium (Ru), and tungsten (W)): (i) barrier-free and liner-free molybdenum film deposition on oxides and nitrides is more feasible than Co, Ru, and W, (ii) molybdenum resistivity scaling is better than W, (iii) below 450°C, molybdenum is not expected to mix with underlying Co compared to Ru and Co mixing, and (iv) molybdenum is relatively easy to integrate into current W solutions compared to Co and Ru.

[0067] Examples of feature filling for horizontally oriented and vertically oriented features are described below. It should be noted that, at least in most cases, these examples apply to both horizontally oriented 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 orthogonal to the plane of the substrate surface.

[0068] The molybdenum deposition described herein involves reacting a Mo-containing precursor (also referred to as a molybdenum precursor). In some embodiments, the molybdenum precursor is molybdenum chloride (MoCl x ) compound, also known as molybdenum chloride precursor or MoCl x Precursor. The molybdenum chloride precursor is composed of the formula MoCl x Given, where x is 2, 3, 4, 5 or 6, and includes molybdenum dichloride (MoCl2), molybdenum trichloride (MoCl3), molybdenum tetrachloride (MoCl4), molybdenum pentachloride (MoCl5), and molybdenum hexachloride (MoCl6). In some embodiments, MoCl5 or MoCl6 is used. Although the description mainly relates to MoCl x Precursors, but in other embodiments, other molybdenum halide precursors may be used. The molybdenum halide precursor is of the formula MoX z Wherein X is halogen (fluorine (F), chlorine (Cl), bromine (Br) or iodine (I)), and z is 2, 3, 4, 5 or 6. MoX z Examples of precursors include molybdenum fluoride (MoF6). In some embodiments, MoX6 without fluorine is used. z Precursors are used to prevent fluorine etching or incorporation. In some embodiments, bromine-free and / or iodine-free MoX z Precursors to prevent etching or incorporation of bromine or iodine.

[0069] In some embodiments, a molybdenum oxyhalide precursor may be used to fill the features. The molybdenum oxyhalide precursor is of the formula MoO y X z Given, 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 Examples of molybdenum oxyhalides include molybdenum dioxide dichloride (MoO2Cl2), molybdenum oxytetrachloride (MoOCl4), molybdenum oxytetrafluoride (MoOF4), molybdenum dioxide dibromide (MoO2Br2), and molybdenum iodide MoO2I and Mo4O 11 I. It should be understood that, as used herein, the term molybdenum oxyhalide precursor may refer to a molybdenum oxyhalide precursor as described above or a molybdenum-containing oxyhalide precursor comprising molybdenum, oxygen, a halide, and one or more other elements. In some embodiments, the molybdenum oxyhalide or molybdenum-containing oxyhalide may include a variety of different halogens (e.g., F and Cl and / or I and / or Br, etc.). MoCl may be used. x Precursor, MoO y X z precursors or a combination thereof to fill features with molybdenum.

[0070] To deposit molybdenum into a feature, the molybdenum precursor can be reacted with a co-reactant. Examples of co-reactants include hydrogen (H2), silane (SiH4), diborane (B2H6), germane (GeH4), ammonia (NH3), and hydrazine (N2H4).

[0071] In some embodiments, the deposition of molybdenum may use a plasma-based process. Gases may be fed into a remote or in-situ plasma generator to generate plasma species. Examples of gases that may be used to generate plasma may be hydrogen-containing gases, such as H2, nitrogen-containing gases, such as N2, and other gases, such as Ar and NH3. The plasma species may be inert or react with the molybdenum precursor to form a film.

[0072] Features may 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) may be used.

[0073] ALD is a surface-mediated deposition technique in which a certain dose of precursors and reactants are sequentially introduced into a deposition chamber. One or more cycles of sequential dosing of molybdenum precursors and reactants can be used to deposit Mo. For example, in the deposition of the initial molybdenum layer, MoCl5 can be used as a precursor and H2 can be used as a reducing agent. A certain dose of MoCl5 and H2 are sequentially introduced into the deposition chamber, and a purge gas (e.g., argon) flows between the deposition chambers. For ALD, the temperature of the substrate and the pressure of the chamber can be controlled. For example, the substrate can be heated to between 300°C and 800°C, such as between 650°C and 750°C. In some embodiments, the chamber can be pressurized between 10Torr and 90Torr, such as between 30Torr and 50Torr. In some embodiments, temperature and / or pressure can be used to control the reaction rate. In some embodiments, temperature and / or pressure can be used to control selectivity. This will be discussed further below.

[0074] In some embodiments, the molybdenum filling may involve CVD. In a CVD process, a molybdenum precursor and a reactant are in a gas phase together in a deposition chamber. Generally speaking, a CVD process fills features faster than an ALD process. In one example, the precursor may be molybdenum chloride, such as MoCl5, and flows into the chamber along with a reactant, such as H2. In this example, the wafer is exposed to the precursor and the reactant simultaneously, which react and fill the feature with Mo.

[0075] In yet other embodiments, a pulsed CVD process may be used to fill the features. A pulsed CVD process flows reactants into the chamber continuously while pulses of precursors flow into the chamber. For example, H2 gas may flow into the chamber and flow into the chamber continuously while MoCl5 flows into the chamber intermittently. The temperature of the substrate and the pressure in the chamber may be controlled during the CVD operation.

[0076] Molybdenum can be selectively deposited into features using the methods described herein. In selective deposition, a molybdenum filler can be deposited more easily on a first material than a second material, for example, molybdenum can be deposited and grown more easily on a metallic material than on a dielectric material. For example, a feature can have a sidewall surface of SiO2 and a TiN plug in the bottom of the feature. In selective deposition, molybdenum is deposited into the feature and can grow on the TiN plug, but not (or to a lesser extent) on the sidewall surface of the SiO2. In this example, the feature avoids the above-mentioned by growing the molybdenum from the bottom of the feature on the TiN plug instead of the sidewall surface. Figure 2L Line bending effect in .

[0077] Processing conditions such as precursor gas, reducing agent, processing temperature, processing pressure, and exposure time can affect the selectivity of the deposited molybdenum film. Different precursor gases can have different processing windows, in which molybdenum films can be selectively deposited. For example, MoCl5 has a higher selectivity than MoO2Cl2, that is, under the same temperature and pressure conditions, the precursor gas of MoCl5 can only deposit molybdenum on the conductive surface, but not on the dielectric surface, while the precursor gas of MoO2Cl2 can deposit molybdenum on both the conductive surface and the dielectric surface. In general, MoCl5 has a large processing window, that is, a large temperature and pressure range, in which the precursor gas maintains its selectivity. For example, MoCl5 can be selectively deposited on a metal material relative to a dielectric material, wherein the processing temperature is 250°C to 800°C, such as 300°C to 500°C. In general, higher processing temperatures and higher processing pressures reduce the selectivity of the deposition gas. For example, at higher temperatures, a precursor gas such as MoCl5 may lose its selectivity and deposit a molybdenum film on both the metal surface and the dielectric surface within the feature.

[0078] MoCl5 can react with different reactants to deposit molybdenum film. Described below is an example of depositing molybdenum film in a feature using MoCl5 precursor and different processing controls. In the first example, the MoCl5 precursor is reacted with hydrogen (H2) reactant using the above-mentioned deposition method. In the description herein, the metal precursor reacts with hydrogen (H2) (also referred to as hydrogen reactant or H2 reactant) as a co-reactant. However, instead of hydrogen, other reactants can be used, including other hydrogen-containing reactants, such as SiH4, B2H6, NH3, depending on the specific situation. Although reactants such as B2H6 and / or SiH4 are stronger reducing agents, they also result in higher resistivity. Therefore, in some embodiments, it is advantageous to use H2 described herein. The processing temperature for selectively depositing molybdenum film can be between 250°C and 800°C, such as 300°C to 500°C. At these temperatures, the molybdenum film is selectively deposited on the conductive metal or metal compound surface in the feature, such as the TiN surface, relative to the dielectric surface. The molybdenum film grows from the location where the conductive surface is located in the feature. If the conductive surface is a TiN plug located at the bottom of the feature, a molybdenum film can be deposited and grown from the bottom of the feature. In a second example, a MoCl5 precursor and H2 reactant can be used to deposit a molybdenum film, but at a higher temperature, i.e., above 800°C. This process window allows the deposition of a molybdenum film on both dielectric and conductive surfaces within the feature. The deposition of a molybdenum film on a dielectric surface can be used to create a barrier-free molybdenum layer in the feature, which will be discussed in more detail below.

[0079] In yet another example, a MoCl5 precursor is reacted with an ammonia (NH3) reactant to deposit a molybdenum film in a feature using the above-described deposition process. In this embodiment, the deposited molybdenum film may have a processing temperature between 200°C and 700°C. At similar temperatures, reacting MoCl5 with NH3 may have a lower selectivity than reacting with H2. In this embodiment, the molybdenum film may be deposited on both dielectric and conductive surfaces in the feature. Temperature treatment can be used to control the composition and crystallinity of the deposited film. At lower processing temperatures, typically below 400°C, an amorphous molybdenum nitride film is deposited. At higher processing temperatures, typically above 500°C, a crystalline molybdenum nitride film may be deposited. Between these ranges, a partially crystalline film having amorphous and crystalline regions may be deposited.

[0080] The etching operation may be used in a method of filling a feature using a molybdenum film. The etching operation removes metal and nitride materials from the feature. For example, the etching process may partially or completely remove a liner layer from the feature. In another example, the etching process may be used to reduce the thickness of the liner layer. In some embodiments, the etching operation may involve soaking the feature in a molybdenum precursor gas. In some embodiments, the etching operation involves using a MoCl5 such as a MoCl2 film to fill the feature. xPrecursor soaking characteristics. In some embodiments, the soaking can be performed continuously with the precursor gas. In some embodiments, the soaking can be pulsed so that MoCl x The precursor is cycled with a sweep gas such as argon (Ar). In yet other embodiments, the features may be exposed to alternative doses of MoCl x Precursors and reactants, such as H2.

[0081] MoCl x Precursors are used in both deposition and etching operations. For example, in a specific processing window, a MoCl5 precursor can simultaneously grow a molybdenum film and etch away a metal or metal compound film in a feature. If the rate of removing material is greater than the material deposited by the precursor, the process is considered a net etching operation. The speed of the precursor depositing material and etching material can be controlled by a variety of processing conditions, including the type of reactants used and the processing temperature. In general, the lower the temperature, the higher the ratio of the etched material relative to the deposited material. At higher temperatures, the same precursor and reactant can be used as a net deposition operation, that is, the amount of deposited material is greater than the amount of removed material. For example, when the processing temperature is less than 400°C, a MoCl5 precursor and H2 reactant can be used in an etching operation. When the processing temperature is greater than 550°C, the same MoCl5 precursor and H2 reactant can be used in a deposition operation.

[0082] In some embodiments, MoCl x Precursors at high temperatures, such as above 550°C, can continue to etch material at a faster rate than the deposited material. For example, MoCl5 can be used to etch features by soaking without reactants. In this example, the temperature can be as high as 700°C and will continue to etch material away from the feature. In an operation where the feature is soaked in MoCl5 without reactants, the elevated temperature may increase the rate at which material is etched away from the feature.

[0083] The features may have surface oxides or contaminants thereon. For example, the surface of the underlying TiN, WN, or W layer may be oxidized. Oxidized surfaces, if left, can result in higher resistivity. Cleaning operations are used to remove such oxides and contaminants. In some embodiments, the cleaning operation may have the features immersed in a molybdenum precursor gas (usually a molybdenum halide). Similar to the etching operation described above, the precursor gas may be MoCl x Precursor. In some embodiments, the soaking can be continuous. In some embodiments, the soaking can be pulsed so that MoCl x The precursor can be an oxygen-free, Cl-containing molybdenum compound capable of removing oxidation from the surface of the feature. xExamples of compounds are provided above. Cl-containing precursors can be used in situations where conventional cleaning using thermal or plasma H2 does not work, such as where oxidative surface stability is present on the surface material. Cl-containing precursors are less likely to over-etch the liner layer of a feature or to erode the surface of a feature than F-containing compounds.

[0084] In some embodiments, filling a feature may involve depositing a nucleation layer. A nucleation layer is a thin layer that supports the bulk deposition. It may be conformal to the feature. In many embodiments, the nucleation layer is deposited by an ALD process. In some embodiments, a molybdenum nucleation layer is deposited using one or more of a boron-containing reducing agent (e.g., B2H6) or a silicon-containing reducing agent (e.g., SiH4) as a co-reactant. For example, a molybdenum nucleation layer may be deposited using one or more S / molybdenum cycles or Mo / S cycles. In another example, a molybdenum nucleation layer may be deposited using one or more B / molybdenum cycles or Mo / B cycles, on which a bulk molybdenum layer is deposited. B refers to a pulse of diborane or other boron-containing reducing agent and S refers to a pulse of silane or other silicon-containing reducing agent, such that S / molybdenum refers to a pulse of a silane followed by a pulse of a Mo-containing precursor. Both B / molybdenum and S / molybdenum cycles (or Mo / B and / or Mo / S) may be used to deposit a molybdenum nucleation layer, such as x(B / Mo)+y(S / Mo), where x and y are integers. Examples of boron-containing reactants include diborane (B2H6), alkylboranes, alkylboranes, aminoboranes (CH3)2NB(CH2)2, carboranes such as C2B n H n+2 and other boranes. Examples of boranes include B n H n+4 , B n H n+6 , B n H n+8 , B n H m , wherein n is an integer from 1 to 10, and m is an integer different from m. Examples of silicon-containing reducing agents include silane (SiH4) and other silanes, such as disilane (Si2H6).

[0085] In some embodiments, deposition of the molybdenum nucleation layer may involve the use of an oxygen-free precursor, such as molybdenum hexafluoride (MoF6) or molybdenum pentachloride (MoCl5). The oxygen in the oxygen-containing precursor may react with a silicon-containing or boron-containing reducing agent to form MoSi x O y or MoB x O y , which are impure high resistivity films. In some embodiments, an oxygen-containing precursor can be used for nucleation layer deposition while minimizing oxygen incorporation. Oxygen incorporation can be minimized by a high reducing agent flow rate (e.g., a volume flow rate of reducing agent to oxygen-containing molybdenum precursor greater than 100:1).

[0086] In some embodiments, H2 may be used as a reducing gas for the deposition of the molybdenum nucleation layer instead of a boron-containing or silicon-containing reducing gas. An exemplary thickness for depositing the molybdenum nucleation layer is to Films at the lower end of this range may not be continuous; however, as long as they can help initiate continuous bulk molybdenum growth, the thickness is sufficient.

[0087] In some embodiments, the reducing agent pulse during deposition of the nucleation layer or bulk molybdenum layer can be performed at a lower substrate temperature than the molybdenum precursor pulse. For example, a B2H6 or SiH4 (or other boron-containing or silicon-containing reducing agent) pulse can be performed at a temperature below 300°C, where the molybdenum pulse is performed at a temperature above 300°C.

[0088] In some embodiments, the reducing agent is NH3 or other nitrogen-containing reducing agents, such as hydrazine (N2H4). The chemical adsorption of NH3 on the dielectric is more favorable than H2. In some embodiments, the reducing agent and precursor are selected so that they react without dissociation of the reducing agent. NH3 reacts with metal oxychlorides and metal chlorides without dissociation. This is in contrast to metal oxychloride ALD, for example, using H2 as a reducing agent, which dissociates on the surface to form adsorbed atomic hydrogen, which results in very low active species concentrations during the initial nucleation of the metal on the dielectric surface and low surface coverage. By using NH3 and metal oxychloride or metal chloride precursors, nucleation delays are reduced or eliminated at deposition temperatures that are up to hundreds of degrees lower than the deposition temperatures used for H2 reduction of the same metal precursors.

[0089] In some embodiments, the reducing agent may be a boron-containing or silicon-containing reducing agent, such as B2H6 or SiH4. These reducing agents can be used with metal chloride precursors, metal oxychlorides; however, B2H6 and SiH4 may react with water formed as a byproduct during the ALD process and form solid B2O3 and SiO2. They are insulating and may remain in the film, thereby increasing resistivity. The use of NH3 also improves adsorption on specific surfaces (including Al2O3) compared to ALD processes of B2H6 and SiH4. The resulting nucleation layer is typically not a pure elemental film but a metal nitride or metal oxynitride film. In some embodiments, there may be residual chlorine or fluorine from the deposition, especially if the deposition is performed at low temperatures. In some embodiments, there may be no more than trace amounts of residual chlorine or fluorine. In some embodiments, the nucleation layer is an amorphous layer. Impurities in the film (e.g., oxygen, NH3, chlorine, or other halogens) are conducive to the growth of amorphous microstructures. In some embodiments, the deposited nucleation layer is an amorphous molybdenum oxynitride layer or an amorphous molybdenum nitride layer. The amorphous nature provides a template for the growth of large grains in the subsequently deposited conductor. The surface energy of the nitride or oxynitride relative to the oxide surface is much more favorable than the surface energy of the metal on the oxide surface, thereby facilitating the formation of a continuous and smooth film on the dielectric. This allows the formation of a thin, continuous layer. When deposited, an exemplary thickness range for the nucleation layer is For example, this could be about 5-50 ALD cycles, depending on the temperature.

[0090] As described below, during subsequent processing, as the thickness decreases, the nucleation layer can be transformed into a pure (or impure) elemental metal film. The surface on which the nucleation layer is deposited depends on the specific application. In some embodiments, the nucleation layer is deposited directly on a dielectric (e.g., silicon oxide, aluminum oxide, silicon nitride, etc.) surface. In some embodiments, the nucleation layer is deposited directly on a titanium nitride or other surface.

[0091] In some embodiments, the ALD formation of the molybdenum layer may be induced by a reducing agent layer. Examples of such processes are Figure 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 provided below. In some embodiments, the reducing agent layer may include silicon or silicon-containing materials, phosphorus or phosphorus-containing materials, germanium or germanium-containing materials, boron or its boron-containing materials capable of reducing molybdenum precursors, and combinations thereof. According to various embodiments, hydrogen may or may not operate in this context. (Although hydrogen can reduce tungsten precursors, it does not act as a reducing agent in a gas mixture with a sufficient amount of a stronger reducing agent (e.g., silane and diborane).) In some embodiments, the reducing agent gas is a mixture comprising a small amount of a boron-containing gas (e.g., diborane) and another reducing agent. The addition of a small amount of a boron-containing gas can greatly affect the decomposition and adhesion coefficient of other reducing agents. It should be noted that the substrate may be exposed to two reducing agents, such as silane and diborane, in sequence. However, flowing the gas mixture may facilitate the addition of very small amounts of minority gases, such as a ratio of silane to diborane of at least 100:1. In some embodiments, a carrier gas may be flowed. In some embodiments, a carrier gas, such as nitrogen (N2), argon (Ar), helium (He), or other inert gas, may be flowed during operation 302.

[0092] In some embodiments, the reducing agent layer may include elemental silicon (Si), elemental boron (B), elemental germanium (Ge), or mixtures thereof. For example, the reducing agent layer may include elemental Si and B. This is different from adsorbed silane or diborane molecules and may involve decomposition of compounds in the reducing agent gas. The amount of B may be adjusted to achieve a high deposition rate of the reducing agent layer but with low resistivity. In some embodiments, the reducing agent layer may have, for example, between 5% and 80% B, or between 5% and 50% B, between 5% and 30%, or between 5% and 20% B, with the balance consisting essentially of Si and, in some cases, H. The presence of hydrogen atoms, such as SiH x , BH y ,GeH z or mixtures thereof, wherein 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 over the thickness of the reducing agent layer. For example, the reducing agent layer can 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 can be between and and in some embodiments, between and between and The reducing agent layer conformally lines the features.

[0093] The substrate temperature during operation 302 can be maintained at temperature T1 to make the film conformal. If the temperature is too high, the film may not conform to the morphology of the underlying structure. In some embodiments, a step coverage greater than 90% or 95% is achieved. For silane, diborane, and silane / diborane mixtures, conformality is excellent at 300°C, but may decrease at 400°C or higher. Therefore, in some embodiments, the temperature during operation 302 is at most 350°C, or even at most 325°C, at most 315°C, or at most 300°C. In some embodiments, a temperature below 300°C is used. For example, the temperature may be as low as 200°C.

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

[0095] In operation 304, the chamber is optionally purged to remove excess reducing agent that is not adsorbed to the substrate surface. The purge may be performed by flowing an inert gas at a fixed pressure, thereby reducing the pressure of the chamber and re-pressurizing the chamber before starting another gas exposure. Exemplary inert gases include nitrogen (N2), argon (Ar), helium (He), and mixtures thereof. The purge may be performed for a duration of about 0.25 seconds to about 30 seconds, about 0.25 seconds to about 20 seconds, about 0.25 seconds to about 5 seconds, or about 0.5 seconds to about 3 seconds.

[0096] In operation 306, the substrate is exposed to a molybdenum precursor at a substrate temperature T2. Using an oxygen-containing precursor can result in impurity incorporation and higher resistivity. However, if oxygen is incorporated, a very thin, possibly discontinuous, reducing agent layer can be used to obtain an acceptable resistivity. In some embodiments, a carrier gas, such as nitrogen (N2), argon (Ar), helium (He), or other inert gas, can be flowed during operation 306. An example of a temperature is 500° C. to 700° C.

[0097] Operation 306 may be performed for any suitable duration. In some embodiments, it may involve an immersion of a molybdenum precursor, and in some embodiments, may involve a sequence of molybdenum precursor pulses. According to various embodiments, operation 306 may be performed in the presence or absence of H2. If H2 is used, then in some embodiments, it and the Mo-containing precursor may be applied in an ALD-type mode. For example: H2 Pulse Argon purge Pulses of Mo-containing precursors with or without H2 in the background Argon purge repeat

[0098] The substrate temperature T2 is high enough so that the Mo-containing precursor reacts with the reducing agent layer to form elemental Mo. The entire reducing agent layer is converted to Mo. In some embodiments, the temperature is at least 450°C, and may be at least 550°C to obtain 100% or near 100% conversion. The resulting features are now lined with a conformal film of Mo. It may be between and and in some embodiments, between and between and In general, its thickness is about the same as the reductant layer. In some embodiments, it can be up to 5% thicker than the reductant layer due to volume expansion during conversion. The chamber can be purged in operation 308. A large portion of the feature can be filled by depositing a bulk molybdenum layer. The bulk molybdenum layer can be deposited on the nucleation layer, the reductant layer, or directly on the underlying surface, as described above.

[0099] The bulk deposition can be performed by ALD or CVD processing. In the CVD process, the reducing agent and the platinum precursor flow together into the deposition chamber to deposit the bulk fill layer in the feature. An inert carrier gas can be used to deliver one or more reactant streams, which may or may not be premixed. The operation generally involves allowing the reactants to flow continuously until the desired amount is deposited. In a particular embodiment, the CVD operation can be performed in multiple stages, wherein multiple time periods of continuous and simultaneous flow of reactants are separated by time periods of one or more diverted reactant streams.

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

[0101] For conformal deposition and deposition into complex structures such as 3D NAND structures, ALD deposition of bulk layers may be used. ALD deposition of bulk layers involves exposure to alternating pulses of a molybdenum-containing precursor and a reducing agent separated by an inert purge gas using the molybdenum precursor described above. The same or different molybdenum precursor used for nucleation layer or reducing agent layer deposition may be used for bulk deposition. In contrast to nucleation layer deposition, which may use strong reducing agents such as diborane or silane, hydrogen is typically the reducing agent used for 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., removing any non-metallic components. The nucleation layer may have more impurities than the subsequently deposited elemental molybdenum layer, but they are sufficiently removed so that the resistivity of the stack is the same or similar to that of the stack that does not include the nucleation layer. As described above, in some embodiments, a molybdenum oxynitride or molybdenum nitride layer can be used as a nucleation layer. Also, in some embodiments, a molybdenum oxide layer can be used as a nucleation layer.

[0103] According to various embodiments, one or more of the following may be employed to facilitate the conversion of the nucleation layer to an elemental molybdenum film: 1) depositing the bulk molybdenum layer at a higher temperature (e.g., 550° C.) than the nucleation layer deposition, 2) performing a lower temperature ALD H2 / molybdenum precursor cycle, and 3) depositing the bulk molybdenum layer in situ such that the nucleation layer is not exposed to air or otherwise oxidized prior to bulk deposition of molybdenum. Molybdenum oxynitride, in particular, is relatively easy to convert to elemental metal. The resulting converted nucleation layer and pure metal layer may each be characterized as having less than 1% atomic impurities.

[0104] As in Figure 1B As described in , molybdenum can be deposited into features without a barrier layer, i.e., molybdenum is deposited on the dielectric surface in the feature. In some embodiments, the above referenced Figure 3 In these embodiments, the reducing agent can be deposited into the feature. Subsequent deposition of a molybdenum precursor can convert the reducing agent layer to Mo as described in operation 308. In some embodiments, molybdenum can be deposited directly onto the dielectric layer by CVD or ALD processing using a molybdenum chloride or molybdenum oxyhalide precursor with reactants as described above.

[0105] In a first example, a seed crystal can be used to deposit molybdenum into a feature having a dielectric surface (e.g., SiO2). The process uses a molybdenum chloride precursor such as MoCl5 and a reactant such as H2. In some embodiments, NH3 can be used as a reactant. As described above, MoCl5 is highly selective and resists growth directly on a dielectric surface compared to a conductive surface. However, if the precursor and reactant have a sufficiently long exposure time to the SiO2 surface, a molybdenum seed crystal will be formed on the SiO2. Due to the precursor selectivity, the exposure time of the molybdenum precursor and reactant to form a seed crystal on the dielectric material is longer than the typical exposure time when depositing molybdenum on a nucleation layer or plug. Once the seed crystal is formed on the dielectric layer, molybdenum can be selectively deposited on the seed crystal formed using the same precursor and reactant.

[0106] Forming the seed may involve one or more of the following. In some embodiments, a molybdenum chloride precursor and a reactant (e.g., H2) are exposed to the SiO2 surface for a long time to allow molybdenum seeds to form on the SiO2. For example, after 200 to 600 ALD cycles using MoCl5 as a precursor and H2 as a reactant, molybdenum seeds may be formed on the dielectric material. In another embodiment, depositing a relatively high amount of reactant compared to the precursor may be used to produce molybdenum seeds on the dielectric surface. During the formation of the molybdenum seeds, the concentration of the precursor may be reduced, thereby increasing the ratio of the reactant to the deposited precursor. In the example of using a MoCl5 precursor and an H2 reactant, having a relatively high ratio of H2 to MoCl5 shortens the deposition delay on the dielectric material and allows the seeds to be produced faster. For seed formation, the concentration of the precursor gas may be reduced by up to 90%, such as 80%, of the normal precursor concentration during normal deposition operations. For example, in a typical ALD process, the precursor concentration may be 1-2% of the gas, i.e., the gas is 98% carrier gas and 2% precursor. In seed formation, the precursor concentration can be reduced by up to 90%, so that the precursor concentration is as low as 0.1% of the gas. In some embodiments, the processing temperature can be increased to improve seed formation. For example, during seed formation, the processing temperature can be above 500°C. In some embodiments, the temperature can be above 500°C during seed formation and can be reduced to below 500°C to selectively grow molybdenum on the seeds formed on the dielectric material.

[0107] In some embodiments, molybdenum oxyhalides such as MoO2Cl2 can be used as precursors to form molybdenum seeds on dielectric surfaces. In these embodiments, the seeds can be formed on the dielectric material faster than seeds formed using molybdenum chloride precursors. However, the deposited molybdenum film may be oxidized.

[0108] In some embodiments, platinum can be selectively deposited on 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 in the bottom of the feature, and platinum is selectively deposited on the plug. The feature can also have a sidewall surface made of a dielectric material. Using the above-mentioned selective etching techniques (i.e., controlling processing parameters such as temperature, pressure, and reactants), platinum can be deposited using a molybdenum halide or molybdenum oxyhalide precursor so that the platinum is selective for the conductive metal plug. The platinum grows on the conductive metal plug instead of the dielectric sidewall.

[0109] In an embodiment where the feature does not have a conductive metal plug, a platinum plug can be formed at the bottom of the feature by depositing a platinum chloride precursor and a hydrogen reactant using the above method. When deposited using (i) a relatively high ratio of a platinum chloride precursor to an H2 reactant, (ii) a relatively high processing pressure compared to selective deposition, or (iii) a combination thereof, a platinum plug can be formed. In some embodiments, a high ratio of a platinum chloride precursor is deposited into the feature to produce a net etching effect at the top of the feature and a net deposition effect at the bottom of the feature, thereby allowing a platinum plug to be formed at the bottom of the feature. The bottom of the feature is the innermost surface of the feature connected by the sidewall. In some embodiments, the platinum plug can be formed at a lower temperature, for example, below 450°C. CVD or pulsed CVD processing can be used to form the platinum plug. In an example of a pulsed CVD process, the H2 reactant can flow continuously into the feature, and the MoCl5 precursor can be pulsed at a concentration between 0.1% and 0.2% for a duration of 0.5 seconds to 2.5 seconds. Once the Mo plug is formed in the bottom of the feature, the processing parameters may be varied to selectively deposit Mo on the Mo plug within the feature.

[0110] Figure 4 4 is a process flow diagram illustrating a method of filling a feature with a molybdenum (Mo) film. The method 400 begins by providing a substrate including a feature in which molybdenum is to be deposited in operation 401. The substrate can be provided to a semiconductor processing tool. The feature can be a trench, a via, or a Figure 2A-2L In some embodiments, the features are formed in a dielectric material. Molybdenum can be deposited in the features to form electrical contact with underlying layers. 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] The features typically have sidewall surfaces and may have a bottom surface. In some embodiments, the sidewall surfaces may be 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 a different material than the bottom surface. For example, the bottom surface may be a metal silicide and the sidewall surfaces may be a silicon oxide, such as SiO2. In some embodiments, the features may not have inclined surfaces. In some such embodiments, the sidewall surfaces intersect at the bottom of the feature.

[0112] Prior to any platinum deposition, a liner layer may line the unfilled feature and form the sidewall surface and / or bottom surface. In some embodiments, the liner layer lines the entire feature and forms the sidewall surface and bottom surface. In some embodiments, the liner layer lines only a portion of the feature. For example, a TiN layer may line the sidewalls without paving the substrate surface. Examples of materials for the liner layer include metal nitrides (e.g., a TiN or tantalum nitride (TaN) barrier layer) and metals (e.g., a Ti adhesion layer).

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

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

[0115] After providing a substrate including features to be deposited with molybdenum, an optional cleaning operation 402 may be performed. Optional cleaning may be used to remove oxides on the surface of the features. In some embodiments, an in-situ cleaning process as described above may be used. In-situ cleaning may use molybdenum halides, such as MoCl5. In some embodiments, hydrogen plasma treatment, hot hydrogen treatment, or reduction treatment may be used to reduce the oxidized metal on the metal substrate at the bottom of the feature. In some embodiments, atomic layer cleaning based on Cl plasma, hydrogen fluoride (HF) vapor cleaning, ammonium fluoride (NH4F) cleaning, or treatment using other reducing agents may be used to reduce oxides on the surface of the features.

[0116] Once the substrate is provided, an initial molybdenum layer is deposited in the feature in operation 403. The initial molybdenum layer is deposited by an ALD method. The initial molybdenum layer is deposited by sequentially introducing a molybdenum precursor and a reducing agent into a deposition chamber. The initial molybdenum layer can be deposited using one or more cycles of continuous dosing of a molybdenum precursor and a reducing agent. In some embodiments, the initial molybdenum layer can be conformally deposited to the feature. In some embodiments, the conformal molybdenum layer can be between 1nm and 5nm. In some embodiments, its thickness does not exceed 2nm. In some embodiments, molybdenum can be non-conformally deposited so that it is selectively deposited on the bottom of the feature relative to the sidewall, for example, a molybdenum plug is deposited in the bottom of the feature.

[0117] For the deposition of the initial molybdenum layer, the molybdenum precursor is a molybdenum halide precursor. In some embodiments, MoCl is used. x As mentioned above, other MoX precursors may be used in other embodiments. z Precursors. Examples of reducing agents used are discussed above. An oxygen-free molybdenum precursor prevents oxidation of the feature surface. It also prevents oxygen incorporation into the initial molybdenum layer. Oxidation increases contact resistance. Lack of oxidation and oxygen incorporation ensures that 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 to between 300° C. and 500° C., such as between 350° C. and 450° C. In some embodiments, the chamber can be pressurized to at least 10 Torr, such as at least 30 Torr or at least 50 Torr.

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

[0120] After depositing the initial molybdenum layer, a molybdenum oxyhalide precursor is used to fill the features with molybdenum in operation 405. As described above, MoO y X z Examples of precursors include MoO2Cl2, MoOCl4, MoOF4, MoO2Br2, MoO2I, and Mo4O 11 I. ALD, plasma enhanced ALD, chemical vapor deposition (CVD), or plasma enhanced CVD may be used to fill the feature. For ALD or CVD, H2 may be used as a reducing agent. The molybdenum oxyhalide precursor is preferably MoCl2, which is used to form the initial molybdenum layer. x Precursors deposit molybdenum faster. For example, for non-plasma treatment, MoO y Xz Precursors can be MoCl x The precursor is used to deposit molybdenum at least twice as fast as the deposition rate of the precursor. Plasma enhanced processing can be used to fill features at lower temperatures and / or increase deposition rates.

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

[0122] Similar to Figure 4 In the feature referenced in operation 401 of , the feature has sidewall surfaces and may have a bottom surface. In some embodiments, the feature may be formed in the dielectric layer as a trench or a via to connect to an underlying layer. Other examples of features are shown above. Figure 2A-2L The above reference Figure 4 Operation 401 of the present invention provides an example of a material for forming a bottom surface and a sidewall surface (including a liner layer). Figure 5 In the discussion of , the feature has a bottom surface and sidewall surfaces. It should be understood that the method can be used to provide any feature on a substrate having an oxidized surface.

[0123] The provided features have at least one oxidized surface. In some embodiments, both the bottom surface and the sidewall surface are oxidized. In some embodiments, only some surfaces (e.g., only the bottom surface) are oxidized. The oxidized surface may be caused by exposing the surface to oxidizing conditions. Examples of oxidizing conditions include exposing the surface to air and treating the surface with oxygen-based thermal or plasma treatment. In some embodiments, the oxidizing conditions occur during substrate processing or transfer operations. In some embodiments, the oxidizing conditions occur during substrate processing or transfer operations. In some embodiments, intentional oxidation is performed. Reference above Figure 4 An example of an oxidized surface is given.

[0124] After providing the substrate, an optional intentional oxidation of the surface may be performed. Intentional oxidation may occur by treating the surface by exposing it to air or by an oxygen-based thermal or oxygen plasma treatment. Intentional oxidation of the surface may be used to increase oxidation of a liner layer, such as a TiN barrier layer. This increases the amount of liner layer removed during in-situ cleaning. Thinning the liner layer in this manner results in a reduction in resistance in the feature.

[0125] After providing a substrate including features in which molybdenum is deposited, an optional cleaning operation 502 may be performed. Optional cleaning may be used to remove oxides on the surface of the features. In some embodiments, hydrogen plasma treatment, thermal hydrogen treatment, or reduction treatment is used to reduce oxidized metal on the metal substrate at the bottom of the features. In some embodiments, atomic layer cleaning of Cl-based plasma, hydrogen fluoride (HF) vapor cleaning, ammonium fluoride (NH4F) cleaning, or treatment using other reducing agents may be used to reduce oxides on the surface of the features.

[0126] Next, in operation 503, the feature undergoes a soak. The feature is soaked in molybdenum chloride (MoCl x ) precursor to remove oxidation from the feature surface. In some embodiments, the soaking can be performed continuously. In some embodiments, the soaking can be pulsed, with the MoCl x and a purge gas such as argon (Ar). The precursor is a non-oxygen, Cl-containing molybdenum compound capable of removing surface oxidation of features. MoCl x Examples of are given above. Cl-containing precursors can be used in situations where conventional cleaning using thermal or plasma H2 cleaning does not work, such as where an oxidized surface is stable on the surface material.

[0127] In one example, a feature may have a TiN barrier layer as its liner. The liner layer may be oxidized to form a TiN x O y Surface layer. Because TiN x O y is stable, so the H2 treatment may not be effective in removing TiN from the TiN layer x O y . Soak the feature in MoCl x Precursors such as MoCl5 can effectively remove oxides on TiN liner layers. For relatively thin liners, F-based precursors such as tungsten fluoride (WF6) may cause over-etching of the liner. F-based precursors may attack the underlying surface, such as the bottom surface of the feature. Figure 5 The in-situ cleaning process prevents over-etching of the TiN liner and attack on the underlying surface. In the example of a TiN barrier layer, the F-based precursor can attack it and / or any underlying metal silicide.

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

[0129] After the feature has been soaked and the oxide has been removed from the surface of the feature, MoCl is used in operation 505. x Deposit molybdenum into features. Molybdenum deposition uses MoCl x , which is the same precursor used to soak the feature in operation 503. The deposited molybdenum is an initial molybdenum layer. In some embodiments, operation 505 may involve filling the feature with MoCl5. In some other embodiments, a molybdenum oxyhalide precursor, MoCl y X z to fill the feature. 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] According to various embodiments, feature filling can be non-selective or selective. In some embodiments, feature filling can be selective to partially fill a feature, followed by a more conformal fill to complete the feature fill. Non-selective deposition can be described herein as conformal deposition, where the deposited layer conforms to the contour of the underlying feature. Such a deposited layer may have a certain thickness non-uniformity.

[0131] For the filling process of operation 505, the temperature of the substrate, the pressure of the chamber, and the time of reactant exposure can be controlled. These process parameters can be used to control the selectivity during the bulk filling of Mo. As in the operation in 503, the substrate can be heated to between 300° C. and 500° C., such as between 350° C. and 450° C. The chamber can be pressurized to at least 10 Torr, such as at least 30 Torr or at least 50 Torr. The reactant exposure time can be at least 5 seconds, such as at least 15 seconds.

[0132] Figure 6 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 bottom of the feature and the underlying material below the bottom surface of the feature. The method 600 begins by providing a substrate having a metal nitride layer in operation 601. The substrate can be provided to a semiconductor processing tool.

[0133] Similar to Figure 4Operation 401 of the invention refers to a feature that generally has a bottom with a bottom surface and a side with a sidewall surface. The feature can be formed in a dielectric layer and connected to an underlying layer. Figure 4 Operation 401 in FIG. 4 gives an example of materials for forming the bottom and the sidewalls.

[0134] In the provided features, 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 sidewall surface and the bottom surface are the metal nitride layer. In some embodiments, the sidewall surface can be a different material than the material of the bottom surface. For example, the bottom surface can be a metal nitride layer and the sidewall surface can 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 oxidizing conditions. In some embodiments, the oxidizing conditions occur during substrate processing or transfer operations. In some embodiments, as described above Figure 5 Intentional oxidation was performed as described in.

[0136] After providing the substrate with the metal nitride layer, an optional clean and / or an optional etch may be performed in operation 602. Cleaning may be used to remove oxide from the field, sidewall surfaces, and bottom surface of the feature, while the optional etch may be used to remove portions of the metal nitride layer on the sidewalls or fields of the substrate. Figure 5 An example of a cleaning process is given in operation 502 of FIG.

[0137] If performed, operation 602 may involve soaking the feature in a molybdenum precursor to remove oxidation and / or remove or reduce a metal nitride layer from the feature. In some embodiments, the soaking may be performed continuously. In some embodiments, a pulsed soak may be used, circulating the precursor gas while the sweep gas flows. In some embodiments, the precursor gas may be circulated alternately with the sweep gas. The precursor gas may be a molybdenum-containing halide compound. In some embodiments, the precursor gas is MoCl x , such as MoCl5. MoCl x An example of is given above.

[0138] For the sweep / etch operation in 602, the temperature of the substrate, the pressure of the chamber in the semiconductor processing tool, and the time the precursor is exposed to the feature can be controlled. In some embodiments, the substrate can be heated to between 300° C. and 500° C., such as between 350° C. and 450° C. In some embodiments, the chamber can be pressurized to at least 10 Torr, such as at least 30 Torr or at least 50 Torr. The total time the precursor is exposed to the feature can be at least 10 seconds, such as at least 60 seconds. As described above, the immersion can be continuous or pulsed.

[0139] In operation 603, an initial molybdenum layer is deposited into the feature. The initial molybdenum layer can be deposited by ALD. The initial molybdenum layer is formed by depositing one or more consecutive doses of a molybdenum precursor and a reducing agent into a deposition chamber. The molybdenum precursor is an oxygen-free molybdenum precursor. The oxygen-free precursor can prevent oxidation of the feature surface and help ensure that the contact resistance remains low. The oxygen-free molybdenum precursor can be a molybdenum-containing halide compound. An example of an oxygen-free molybdenum precursor can be MoCl x Precursor, which is described above. In some embodiments, the precursors in operations 602 and 603 can be the same. Figure 4 An example of a reducing agent is given in operation 403 of . The initial molybdenum layer may be selectively deposited into the features on the metal nitride layer. The molybdenum is deposited so that the molybdenum layer becomes the bottom surface of the feature. In some embodiments, the conformal molybdenum layer may be between 1 nm and 5 nm. In some embodiments, its thickness does not exceed 2 nm.

[0140] For the deposition operation in 603, the temperature of the substrate, the pressure of the chamber in the semiconductor processing tool, and the time that the precursor is exposed to the feature can be controlled. In some embodiments, the substrate can be heated to between 350°C and 700°C, such as between 375°C and 475°C. In some embodiments, the chamber can be pressurized to at least 10Torr, such as at least 30Torr or at least 50Torr. The total time that the precursor is exposed to the feature can be at least 10 seconds, such as at least 60 seconds. As described above, the soaking can be continuous or pulsed. In some embodiments, the substrate temperature during operation 603 is higher than the substrate temperature in operation 602, such as 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 metal nitride layer below 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. Etching is performed so 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 connection on the bottom of the feature. The etching can use the same or different precursors 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 precursor exposure time, or a combination thereof than in operation 602.

[0141] After removing the metal nitride layer and the molybdenum layer from the sidewall of the feature in operation 605, the feature is filled with molybdenum in operation 607. The feature can be filled by using ALD or CVD (including thermal and plasma enhanced ALD and CVD processing). Molybdenum halides or molybdenum oxyhalides can be used as precursors 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 into the feature, and then a molybdenum oxyhalide precursor is used for the bulk molybdenum filling. For example, MoCl5 can be used as a precursor to fill the feature first, and then MoO2Cl2 is used to fill it. Examples of molybdenum halides and molybdenum oxyhalides precursors are as described above. According to various embodiments, feature filling can be non-selective or selective. In some embodiments, feature filling can be selective to partially fill the feature, followed by a more conformal filling to complete the feature filling.

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

[0143] Figure 7 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 can be a nitride plug or a nitride layer in the bottom of the feature. The method 700 begins by providing a substrate having a metal nitride feature in operation 701. The substrate can be provided to a semiconductor processing tool.

[0144] The feature typically has two sidewall surfaces that meet at the bottom of the feature. The two sidewall surfaces are typically sloped so that the feature is "V-shaped". It can be formed in a dielectric layer as a trench or via and connected to the underlying layer. Figure 4 Operation 401 in FIG. 4 gives an example of materials for forming the bottom and the sidewalls.

[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 may conformally line the feature so that the sidewall surface is the metal nitride layer. In some embodiments, the metal nitride layer may line a portion of the sidewall so that the bottom of the sidewall surface is the metal nitride layer and the top of the sidewall surface is the dielectric material. Examples of metal nitrides are TiN and TiSiN.

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

[0147] After providing the substrate with the metal nitride features, an optional clean and / or an optional etch may be performed in operation 702. Cleaning may be used to remove oxide from the field and feature surfaces, while the optional etch may be used to remove portions of the metal nitride layer on the sidewalls or fields of the substrate. Figure 5 An example of a cleaning process is given in operation 502 of . After the optional etch, a metal nitride surface is located at the bottom of the feature.

[0148] If performed, operation 702 may involve immersing the feature in a molybdenum precursor to remove oxidation and / or remove or reduce a metal nitride layer from the feature. In some embodiments, the etch may etch more material at the top of the feature relative to the bottom. In a first example, the metal nitride layer may conformally line the feature. The etch may remove the metal nitride layer at the top of the feature and leave the metal nitride layer at the bottom of the feature. In this example, the top of the sidewall surface may be a dielectric material while the top of the sidewall surface may be a metal nitride layer. As discussed above in operation 602, the precursor gas may be continuously immersed, may be pulsed, or alternate with another gas such as a sweep gas. In some embodiments, the precursor gas may be a molybdenum-containing halide precursor. For example, the precursor gas may be MoCl x .MoCl x Examples of are given above. In some embodiments, the etch may be a net etch as described above. In this example, the net etch may react platinum chloride with a reactant such as H2. Platinum may be deposited at the bottom of the feature while the platinum chloride etches away portions of the metal nitride liner at the top of the feature. For the cleaning / etching operation in 602, the temperature of the substrate, the pressure of the chamber in the semiconductor processing tool, and the time the precursor is exposed to the feature may be controlled. These process controls are similar to the process controls discussed in operation 602.

[0149] As discussed above in operation 602, for ALD, the temperature of the substrate and the pressure of the chamber may be controlled. These process parameters may be used to control selectivity so that an initial layer of molybdenum is initially deposited on the metal nitride surface at the bottom of the feature. In some embodiments, the substrate may be heated to between 300° C. and 500° C., such as between 350° C. and 450° C. In some embodiments, the chamber may be pressurized to at least 10 Torr, such as at least 30 Torr or at least 50 Torr.

[0150] In operation 703, an initial molybdenum layer is selectively deposited onto the metal nitride feature at the bottom of the feature. In embodiments where the feature has a metal nitride layer, the molybdenum is deposited on the metal nitride layer at the bottom of the sidewall surface in the bottom of the feature. In embodiments where the feature has a metal nitride plug, the molybdenum is deposited on the metal nitride plug in the bottom of the feature. The initial molybdenum layer may grow upward from the metal nitride surface at the bottom of the feature. Molybdenum may 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 MoCl5, and the reactant may be H2. Examples of additional precursors and reactants are listed above.

[0151] As discussed above in operation 603, for ALD, the temperature of the substrate and the pressure of the chamber can be controlled. These processing parameters can be used to control the selectivity so that the initial layer of molybdenum is initially deposited on the metal nitride surface on the bottom of the feature. In some embodiments, the substrate can be heated to between 350°C and 700°C, such as between 375°C and 475°C. In some embodiments, the chamber can be pressurized to at least 10 Torr, such as at least 30 Torr or at least 50 Torr. In some embodiments, the substrate temperature during operation 703 is greater than the substrate temperature in operation 702, such as 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 depositing the initial molybdenum layer, the features are filled with molybdenum in operation 705. The molybdenum fill is deposited on the initial molybdenum layer deposited in operation 703. The filling can be done using the same molybdenum halide precursor used in the previous operation, or it can be filled with a molybdenum oxyhalide precursor. The precursor can be deposited using a reactant such as H2. The features can be filled using ALD, plasma enhanced ALD, CVD, or plasma enhanced CVD.

[0153] Figures 8A-8D show Figure 7 illustrative example of the processing of . Fig. 8A Feature 801 is shown formed in dielectric material 803. Feature 801 has a metal nitride layer 805 conformally deposited into feature 801. In some embodiments, metal nitride layer 805 is a TiN layer. The metal nitride layer forms two sidewall surfaces 807. Feature 801 is a V-shaped trench and has sidewall surfaces 807 that meet at a bottom 813 of the feature.

[0154] Figure 8B Shown in the experience as above Figure 7 The feature 801 after the cleaning and etching operations described in operation 702. The feature has been subjected to the cleaning and etching operations using MoCl x The soaking of the precursor effectively removes the oxide. The soaking also removes the top of the metal nitride layer 805 so that the metal nitride layer 805 remains in the bottom 813 of the feature 801. After the cleaning operation, each sidewall surface 807 has the metal nitride layer 805 on the bottom sidewall surface and the dielectric material 803 on the top of each sidewall surface.

[0155] Figure 8C Depicted in Figure 7The feature 801 after depositing the initial molybdenum film 809 into the feature 801 as described in operation 703 of FIG. The initial molybdenum film 809 is selectively deposited such that the initial molybdenum film is deposited on the surface of the metal nitride layer 805 in the bottom 813 of the feature 801. The initial molybdenum film 809 is little or not deposited on the dielectric material 803 forming the sidewall surface 807 in the upper portion of the feature 801. Therefore, the molybdenum film 809 is deposited and fills from the bottom 813 of the feature 801.

[0156] Fig.8D Shows Figure 7 The feature 801 after filling the feature with molybdenum 815 as described in operation 705 of FIG. 8 is deposited on the Figure 8C The initial molybdenum layer 810 shown is grown upward from the bottom 813 of the feature until the feature is filled with Mo. ALD, plasma enhanced ALD, CVD, or plasma enhanced CVD may be used to fill the feature. In some embodiments, the filler uses a molybdenum oxyhalide precursor, such as MoO2Cl2. In some embodiments, the filler uses a molybdenum halide precursor, such as MoCl5.

[0157] Figures 9A-9D show Figure 7 illustrative example of the processing of . Fig. 9A Feature 901 is shown formed in dielectric material 903. Feature 901 has sidewall surfaces 907 and a bottom surface 908. Feature 901 has a metal nitride layer 905 conformally deposited into feature 901. In some embodiments, metal nitride layer 905 is a TiN layer. The metal nitride layer forms two sidewall surfaces 907 and a bottom surface 908.

[0158] Fig. 9B Shown in the experience as above Figure 7 Feature 901 after the cleaning and etching operations described in operation 702. The feature has been subjected to the cleaning and etching operations using MoCl x The precursor is soaked, which effectively removes the oxide. The soak also removes the top of the metal nitride layer 905, so that the metal nitride layer 905 remains in the bottom 913 of the feature 901. After the cleaning operation, each sidewall surface 907 has the metal nitride layer 905 on the bottom sidewall surface and the dielectric material 903 on the top of each sidewall surface. The metal nitride layer 905 is still the bottom surface 908 of the feature 901.

[0159] Fig. 9C Describes how Figure 7The feature 901 after the initial molybdenum film 909 is deposited into the feature 901 as described in operation 703 of FIG. The initial molybdenum film 909 is selectively deposited so that the initial molybdenum layer is deposited on the surface of the metal nitride layer 905, namely, the sidewall surface 907 and the bottom surface 908 in the bottom 913 of the feature 901. The initial molybdenum film 909 is rarely or not deposited on the dielectric material 903 formed on the sidewall surface 907 in the upper portion of the feature 901. Therefore, the molybdenum film 909 is deposited and fills from the bottom 913 of the feature 901.

[0160] Fig.9D Display as Figure 7 The feature 901 after filling the feature with molybdenum 915 as described in operation 705 of FIG. Fig. 9C The initial molybdenum layer shown is grown upward from the bottom 913 of the feature until the feature is filled with Mo. ALD, plasma enhanced ALD, CVD, or plasma enhanced CVD may be used to fill the feature. In some embodiments, the filler uses a molybdenum oxyhalide precursor, such as MoO2Cl2. In some embodiments, the filler uses a molybdenum halide precursor, such as MoCl5.

[0161] Figures 10A-10C show Figure 7 A second illustrative example of processing of . Fig. 10A Shown is a feature 1001 formed in a dielectric material 1003. Feature 1001 is a V-shaped trench and has sidewall surfaces 1007 that meet at a bottom 1013 of the feature. Sidewall surfaces 1007 are dielectric material 1003. Feature 1001 has a metal nitride plug 1011 located in the bottom 1013 of feature 1001. In some embodiments, metal nitride plug 1011 is a TiN plug.

[0162] Fig. 10B Depicted in Figure 7 Feature 1001 after depositing an initial molybdenum layer 1009 into feature 1001 as described in operation 703 of FIG. The initial molybdenum film 1009 is selectively deposited onto the metal nitride plug 1011 in the bottom 1013 of feature 1001. Figure 8C Similar to the schematic diagram in , the initial molybdenum layer 1009 has little or no deposition on the sidewall surface 1007 of the dielectric material 1003.

[0163] Fig. 10C Display as Figure 71001 after filling the feature with molybdenum 1015 as described in operation 705 of . A molybdenum filler is deposited on the initial molybdenum layer. Feature 1001 is filled from the bottom 1013 of the feature and grows upward. ALD, plasma enhanced ALD, CVD, or plasma enhanced CVD may be used to fill the feature. In some embodiments, the filler uses a molybdenum oxyhalide precursor, such as MoO2Cl2. In some embodiments, the filler uses a molybdenum halide precursor, such as MoCl5.

[0164] Fig.11 is a process flow diagram illustrating a method of filling a feature without a metal surface with a molybdenum film. The method 1100 begins by providing a substrate without a metal surface in operation 1101. The substrate may be provided to a semiconductor processing tool.

[0165] The feature typically 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 are typically sloped so that the feature is V-shaped. It may be formed in a dielectric layer as a trench or via and connected to an underlying 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 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 can be a molybdenum chloride precursor, such as MoCl5. H2 can be used as a reactant using the above method. When deposited using (i) a relatively high ratio of a molybdenum chloride precursor to a H2 reactant, (ii) a relatively high process pressure during deposition, or (iii) a combination thereof, a molybdenum plug can be formed in the bottom of the feature. In some embodiments, the substrate temperature used to form the plug can be less than 450°C.

[0167] In operation 1105, an initial molybdenum layer is selectively deposited onto the molybdenum plug at the bottom of the feature. Process parameters are controlled so that the initial molybdenum layer is deposited onto the molybdenum plug at the bottom of the feature. The initial molybdenum layer may be deposited by ALD, plasma enhanced ALD, CVD, or plasma enhanced CVD using a molybdenum-containing halide precursor and reactants. The molybdenum-containing halogenated precursor may be a molybdenum chloride precursor, such as MoCl5. The reactant may be H2. Examples of additional precursors and reactants are listed above.

[0168] As discussed above in operation 603, for ALD, the temperature of the substrate and the pressure of the chamber may be controlled. These process parameters may be used to control the selectivity so that an initial layer of molybdenum is initially deposited on the metal nitride surface at the bottom of the feature. In some embodiments, the substrate may be heated to between 300° C. and 500° C., such as between 350° C. and 450° C. In some embodiments, the chamber may be pressurized to at least 10 Torr, such as at least 30 Torr or at least 50 Torr.

[0169] After the initial molybdenum layer is deposited on the molybdenum plug, the feature is filled with molybdenum in operation 1107. The molybdenum fill is deposited on the initial molybdenum layer deposited in the previous operation. The filling can be done using the same molybdenum halide precursor used in the previous operation, or a molybdenum oxyhalide precursor can be used to fill in the operation. The precursor can be deposited using a reactant such as H2. 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. Figures 12A-12C A schematic example of such a process is shown. Fig. 12A A feature 1201 is shown formed in a dielectric material 1203. Feature 1201 has a metal layer 1205 conformally deposited into feature 1201. Feature 1201 also has a metal plug 1211. The metal may be, for example, Mo. The metal layer forms two sidewall surfaces 1207. Feature 1201 is a V-shaped trench and has sidewall surfaces 1207 that meet at a bottom 1213 of the feature.

[0171] Fig. 12B Feature 1201 is shown after undergoing an etching operation. The feature is etched using a molybdenum-containing precursor. Examples include MoCl5 and MoOCl4. The etching removes the top of the metal layer 1205 so that the metal layer 1205 remains in the bottom 1213 of the feature 1201. After etching, each sidewall surface 1207 has dielectric material 1203 on the top of each sidewall surface. Metal plug 1211 remains in the feature. In some embodiments, the metal layer 1205 can be located on the lower portion of the sidewall surface 1207.

[0172] Fig. 12C Feature 1201 is shown 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 Fig. 12B, and grows upward from the bottom 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 filler uses a molybdenum oxyhalide precursor, such as MoO2Cl2. In some embodiments, the filler uses a molybdenum halide precursor, such as MoCl5.

[0173] In some embodiments, one or more of the following techniques may be used to reduce the resistivity. The first technique is to use a high flow rate to flow the gas into the chamber. The high flow rate may be about 5 slm to about 60 slm, such as between about 10 slm and 50 slm. In one example, the high flow rate may be used to flow H2 gas into the chamber. In another example, the high flow rate may be used to flow a purge gas (e.g., Ar) into the chamber.

[0174] The second technique is to use multiple H2 pulses as a reactant. In the deposition of the film, after the precursor flows into the chamber, H2 can be used as a reactant. In some embodiments, multiple pulses of H2 gas can be used to react with the precursor. For example, a precursor gas flows into the chamber, followed by two or more H2 reactant pulses. In some embodiments, H2 can be pulsed sequentially. In some embodiments, the sequence can be to flow H2 gas into the chamber, followed by a purge operation, and then a second H2 gas flows into the chamber. In some embodiments, the H2 gas flow, purge operation sequence can be continuous two or more times.

[0175] A third technique is to use a charge volume. A charge volume can be used to increase the mass flow of gas entering the chamber. In some embodiments, multiple charge volumes can be used. By using multiple charge volumes, the mass flow of gas can be increased as it 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 reactants (e.g., H2) into the chamber. In some embodiments, the charge volume can be used to flow a purge gas. By using a charge volume to flow a purge gas into the chamber, the chamber can be purged faster.

[0177] exist Fig.13 Shown in is an exemplary sequence that can be used to reduce resistivity. In the sequence shown, a molybdenum-containing precursor first flows into the chamber. Examples of molybdenum-containing precursors are given above. The flow of the molybdenum-containing precursor is followed by a purge operation. After the purge operation, the pressure in the chamber is evacuated to a lower pressure. After the chamber pressure is evacuated, hydrogen flows into the chamber. The hydrogen is followed by a purge operation and then the chamber pressure is evacuated. As described above, evacuating the chamber pressure reduces the chamber pressure. The microcycle of flowing hydrogen followed by the purge operation and evacuation of the chamber pressure may be repeated multiple times. In some embodiments, the microcycle may be cycled two or more times. Fig.13 In the sequence shown, a mini-cycle of flowing hydrogen followed by a purge operation and chamber pressure evacuation is cycled three times.

[0178] In some embodiments, multiple air-filled volumes may be used for each sweeping operation. This is described in WO2020 / 214732, which is incorporated herein by reference.

[0179] In some embodiments, one or more of the following techniques may be used to reduce grain boundaries. In the first technique, an inhibitor may be used on the sidewalls of the feature. During the deposition of molybdenum into the feature, an inhibitor may be used on the sidewalls to slow down or stop the growth of molybdenum on the sidewalls. The second technique is to etch or remove any Mo nuclei on the sidewalls of the feature. For example, during etching as described above, MoCl5 may be used to etch the Mo nuclei on the sidewalls of the feature. In another example, molybdenum oxychloride (MoOCl4) may be used to etch the Mo nuclei on the sidewalls. An exemplary process may include depositing molybdenum into the feature. In the initial deposition of molybdenum, the molybdenum nuclei may be deposited on the sidewalls of the feature. An etching operation may be performed after deposition. An exemplary etching operation may be performed using MoCl5 for etching. Etching may etch a portion of the Mo deposited into the feature, including any Mo nuclei deposited on the sidewalls. Deposition may be performed after etching. Deposition may include depositing Mo. Deposition may be a bottom-up fill, depositing molybdenum onto the molybdenum in the feature that was not etched away in the previous operation.

[0180] In 3D NAND structures, treatment of lateral features (e.g., word lines) can be used to improve fill within the structure. Treatment can include nucleation inhibition, etching, or a combination thereof. Nucleation inhibition inhibits subsequent nucleation of molybdenum at the treated surface. It can involve one or more of the following: deposition of an inhibition film, reaction of a treatment substance with the Mo film to form a compound film (e.g., Mo2N), and adsorption of an inhibition substance. During subsequent deposition operations, there is a nucleation delay on the inhibited portion of the underlying film relative to the non-inhibited portion or the less inhibited portion. As Fig.14AAs shown, the inhibitor non-conformally treats the feature. The amount of inhibitor 1403 is higher toward the outside of the feature, and the amount of inhibitor 1403 decreases as one moves toward the inside of the feature. A higher amount of untreated Mo film 1405 is located on the inside of the feature. In the example shown, the Mo film 1405 may be deposited on the inside of the feature. In subsequent depositions, the deposited Mo may be deposited on the Mo within the feature while the inhibitor reduces or delays the growth of Mo. Examples of inhibitors include ammonia (NH3), oxygen (O2), nitrogen (N2), H2, methane (CH4), hydrazine (N2H4), nitrogen trifluoride (NF3), SiH4, B2H6, and derivatives thereof, with or without plasma.

[0181] Etching removes the deposited film at the treated surface. This may involve an etchant species reacting with the molybdenum film to form gaseous byproducts, which are subsequently removed. Other etching methods may be performed, including atomic layer etching. The etching operation may be a plasma or non-plasma operation. If a non-plasma operation, it may be purely thermal or activated by some other energy (e.g., UV).

[0182] Nitrogen is used as an inhibitory species and halogen (e.g., fluorine and chlorine) species are used as etchants. To perform a purely inhibitory process, one example includes treating the feature with a nitrogen-containing chemistry that does not contain halogens. To perform a purely etching process, the process includes exposing the Mo film to a halogen-containing chemistry that does not contain nitrogen. Other inhibitory chemistries (e.g., oxygen-containing chemistries) may be used in some embodiments. Exposing the film to nitrogen-containing and halogen-containing chemistries (e.g., nitrogen trifluoride (NF3) or ammonia / fluorine (NH3 / F2) can both inhibit and etch.

[0183] Fig. 14B , features after a sequence of deposition, etching, deposition are shown in FIG. Mo can be deposited into the features using a conformal ALD process. As shown, Mo is uniformly deposited conformally around each feature from the outside (slit side) to the inside (non-slit side). After deposition, an etching operation can be performed. The etching can be non-conformal etching, so that the etching removes more Mo film on the outside of the word line. On the outside of the word line, the oxide of the feature can be exposed. The inside of the word line can be etched less, so that Mo can remain on the internal features. A second deposition operation can be performed after the etching operation shown. The deposition can be selective for the Mo film that remains on the film. Therefore, the film deposited in the subsequent deposition can be selectively deposited to the inside of the word line. When Mo begins to grow, the deposition can become conformal. As shown, after the subsequent deposition, the Mo film on the inside of the feature can be thicker than the outside of the feature.

Claims

1. A method comprising: (a) providing a substrate comprising a feature having an opening and a sidewall, wherein a metal nitride layer lines the sidewall of the feature; (b) at least partially etching the metal nitride layer along the sidewalls of the feature using a molybdenum-containing halide compound to leave a first portion of the metal nitride layer in the feature; and (c) after at least partially etching the metal nitride layer, 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. 2 . The method of claim 1 , wherein (b) comprises removing metal nitride from a portion of the sidewall to expose the portion of the sidewall of the feature.

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

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

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

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

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

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

9. The method of claim 1 wherein the metal nitride layer conformally lines the feature.

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

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

12. The method of claim 1, wherein the first reactant is hydrogen (H2).

13. The method of claim 1, wherein: (b) being performed at a first substrate temperature; (c) being performed at a second substrate temperature; and The second substrate temperature is higher than the first substrate temperature.

14. A method comprising: (a) providing a substrate comprising features, the features comprising openings, closed ends, 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.

15. The method of claim 14 wherein the sidewalls are sloped and meet at the closed end of the feature.

16. The method of claim 14, further comprising, after (c), (d), filling the feature with molybdenum.

17. The method of claim 16, wherein (d) comprises reacting a second molybdenum-containing halide compound with the second reactant.

18. The method of claim 16, wherein (d) comprises reacting the molybdenum-containing oxyhalide compound with a second reactant.

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

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

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

22. The method of claim 14, wherein the first reactant is hydrogen (H2).

23. The method of claim 14, wherein (b) is performed at a substrate temperature below 450°C.

24. A method comprising: (a) providing a substrate including a feature having a metal nitride plug; and (b) selectively depositing molybdenum on the metal nitride plug in the feature by reacting a molybdenum-containing halide compound with a first reactant.

25. The method of claim 24, further comprising, between (a) and (b), cleaning the feature using the molybdenum-containing halide compound.

26. The method of claim 24, further comprising, after (b), (c), filling the feature with molybdenum.

27. The method of claim 24 or 25, wherein the molybdenum-containing halide compound is a molybdenum chloride compound.

28. The method of claim 24 or 25, wherein the molybdenum-containing halide compound is molybdenum pentachloride.

29. The method of claim 24, wherein the first reactant is a hydrogen-containing reactant.

30. The method of claim 26, wherein filling the feature with molybdenum comprises reacting a second molybdenum-containing halide precursor with a second reactant.

31. The method of claim 26, wherein filling the feature with molybdenum comprises reacting a molybdenum-containing oxyhalide precursor with a second reactant.

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