In feature planarization for molybdenum fill

Abstract

Provided herein are methods and apparatus for in-feature planarization of molybdenum (Mo) deposition. The method involves oxidizing or nitriding a portion of the molybdenum-containing material to form molybdenum oxide or molybdenum nitride, and selectively etching the molybdenum oxide or molybdenum nitride. The method may be used to reduce variations within the feature or between the features. For example, line-to-line variation, in-line roughness, and line bending may be improved. The methods described herein may be used for logic and memory applications and may be used to deposit molybdenum in a semiconductor substrate with features such as vias, wordlines such as dynamic random-access memory (DRAM) buried wordline (bWL), and trenches. The method may be used to deposit molybdenum to fill features as liner layer and / or fill features.

Description

IN FEATURE PLANARIZATION FOR MOLYBDENUM FILLINCORPORATION BY REFERENCE

[0000] A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in its entirety and for all purposes.BACKGROUND

[0001] Deposition of conductive materials is an integral part of many semiconductor fabrication processes. These materials may be used for horizontal interconnects, vias between adjacent metal layers, contacts between metal layers and devices, and as lines in memory devices. In an example of deposition, a tungsten (W) layer may be deposited on a titanium nitride (TiN) barrier layer to form a TiN / W bilayer by chemical vapor deposition (CVD) process using tungsten hexafluoride (WFe). However, as devices shrink and more complex patterning schemes are utilized in the industry, the deposition of thin tungsten becomes a challenge. The continued decrease in feature size and film thickness brings various challenges to TiN / W film stacks. These include high resistivity for thinner films and deterioration of TiN barrier properties. Deposition in complex high aspect ratio structures such as 3D NAND structures and DRAM buried wordline (bWL) is particularly challenging.

[0002] For some applications, molybdenum (Mo) offers several benefits over other metals such as cobalt (Co), ruthenium (Ru), and tungsten (W): (i) barrierless and linerless deposition is more feasible on oxides and nitrides as compared to deposition of cobalt, ruthenium, and tungsten, (ii) Mo resistivity scaling is better than that of tungsten, (iii) Mo intermixing with underlying Co is not expected compared to Ru intermixing with Co at temperatures less than 450°C, and (iv) there is relatively easy Mo integration into current W schemes compared to copper and ruthenium.

[0003] The background description provided herein is for the purpose of generally presenting the context of disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] Provided herein are the methods and apparatus for in-feature planarization of molybdenum fill.

[0005] One general aspect of the disclosure includes a method for processing substrate where the method includes (a) providing a substrate having a plurality of features spaced apart where each feature has a feature opening and molybdenum-containing material deposited therein, each feature has a depth from the feature opening to a surface of the molybdenum-containing material therein, and the feature-to-feature depth is nonuniform, (b) oxidizing a portion of the molybdenum- containing material to form a molybdenum oxide, and (c) selectively etching the molybdenum oxide with respect to the molybdenum-containing material to thereby expose the underlying molybdenum-containing material, where the feature-to-feature depth non-uniformity after performing (a) - (c) is lower than that in (a).

[0006] Implementations may include one or more of the following features. In some embodiments, the molybdenum-containing material is deposited on a metal nitride plug, such as a titanium nitride plug, and the molybdenum-containing material is selectively deposited on the titanium nitride plug by exposing the titanium nitride plug to a molybdenum halide precursor and exposing the molybdenum halide precursor to reducing agent, thereby forming a molybdenum-containing material. In some embodiments, the molybdenum halide precursor is molybdenum pentachloride, and the reducing agent is hydrogen. In some embodiments, molybdenum-containing material is deposited in the feature by atomic layer deposition.

[0007] In some embodiments, the method includes exposing the featured substrate to an oxygencontaining plasma. In some embodiments, the oxy gen-containing plasma is generated from a process gas that may include oxygen (O2). In some embodiments, the process gas may further include one or more other gases, such as hydrogen (H2) gas and argon gas. In some embodiments, the process gas contains at least 20 % (vol.) of O2 or 20 - 30 % (vol.) of O2.

[0008] In some embodiments, an oxygen-containing plasma is ignited using a capacitively coupled plasma generator, inductively coupled plasma generator, or is generated in a remote chamber. In some embodiments, oxy gen-containing plasma is ignited using a power between 150 W and 1000 W.

[0009] In some embodiments, the method includes exposing the featured substrate to a thermal soaking process using at least one of ozone, oxygen gas, and water.

[0010] In some embodiments, the oxidation forms molybdenum oxide having a thickness between 5 nm and 25 nm in each feature.

[0011] In some embodiments, the oxidation is performed at temperatures between 225°C and 400°C.

[0012] In some embodiments, the oxidation is performed at pressures between 0.4 torr and 10 torr.

[0013] In some embodiments, the oxidation, i.e., operation (b), may be repeated between 1 and 40 times.

[0014] In some embodiments, the molybdenum oxide is selectively etched by exposing the molybdenum oxide to one or more of: molybdenum pentachloride (M0CI5), chlorine (Ch), boron trichloride (BCh), carbon tetrachloride (CCI4), hydrogen fluoride (HF), tungsten hexafluoride (WFe), and nitrogen trifluoride (NF3). In some embodiments, etch selectivity between the molybdenum oxide and the molybdenum-containing material is at least 100: 1, or at least 500:1.

[0015] In some embodiments, after selectively etching the molybdenum oxide, the method further may include depositing additional molybdenum-containing material over the underlying molybdenum-containing material to fill the plurality of features.

[0016] In some embodiments oxidizing the molybdenum-containing material and selectively etching the molybdenum oxide may be repeated one or more times.

[0017] In some embodiments, prior to oxidizing the molybdenum-containing material, native oxide on the molybdenum-containing material may be removed.

[0018] Another general aspect of the disclosure includes a method for processing a featured substrate where the method includes (a) providing a substrate having a plurality of features spaced apart where each feature has a feature opening, a feature depth, and molybdenum-containing material deposited therein, where the molybdenum-containing material is deposited to a nonuniform depth from the feature opening (b) oxidizing a portion of the molybdenum-containing material to form a molybdenum oxide, and (c) converting molybdenum oxides to molybdenum- containing material.

[0019] Implementations may include one or more of the following features. In some embodiments, converting molybdenum oxides to molybdenum-containing material may include soaking the featured substrate in hydrogen gas. The method may further include removing byproducts such as fluorine or chlorine.

[0020] Another general aspect of this disclosure includes a method for processing a featured substrate. The method may include (a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening, a feature depth, and molybdenum-containing material deposited therein, where the molybdenum-containing material is deposited to a nonuniform depth from the feature opening, (b) nitriding a portion of the molybdenum-containing material to form a molybdenum nitride, (c) selectively etching the molybdenum nitride, and (d) exposing an underlying molybdenum-containing material having a uniform depth from the feature opening.

[0021] Another general aspect includes a method for processing a featured substrate. The method may include (a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening and a feature bottom, where a layer of titanium nitride is deposited on the feature bottom, (b) oxidizing a portion of the titanium nitride to form a titanium oxynitride, (c) selectively etching the titanium oxynitride, and (d) depositing a molybdenum-containing material in each feature.

[0022] Implementations may include one or more of the following features. In some embodiments, oxidizing tin nitride involves exposing the titanium nitride to a hydrogen-containing plasma.

[0023] In some embodiments, selectively etching the titanium oxynitride includes exposing the titanium oxynitride to at least one of the boron trichloride (BCh), hydrogen fluoride (HF), tungsten hexafluoride (WFe), and nitrogen trifluoride (NF3).

[0024] Another general aspect includes a method of processing a featured substrate. The method includes (a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening and a feature bottom, where a titanium nitride is deposited on the feature bottom, and where the titanium nitride may include titanium oxynitride; (b) selectively etching the titanium oxynitride, and (c) depositing a molybdenum-containing material in each feature.

[0025] In some embodiments, selectively etching the titanium oxynitride involves exposing it to at least one of boron trichloride (BCh), hydrogen fluoride (HF), tungsten hexafluoride (WFe), and nitrogen trifluoride (NF3).

[0026] In some embodiments, the resistivity of the molybdenum-containing material is decreased.BRIEF DESCRIPTION OF DRAWINGS

[0027] Figures 1A and IB are schematic examples of material stacks that include molybdenum layers according to various embodiments.

[0028] Figures 2A - 2L are schematic examples of various structures into which molybdenum may be deposited in accordance with disclosed embodiments.

[0029] Figure 3 shows an example of a molybdenum (Mo) interconnect according to various embodiments.

[0030] Figure 4 shows examples of patterned features into which selective deposition of a Mo film may be performed according to various embodiments.

[0031] Figure 5 A provides an illustrative example of in-feature planarization according to various embodiments.

[0032] Figure 5B shows a process flow diagram illustrating operations in a method for in-feature planarization of molybdenum-containing material via oxidation.

[0033] Figure 6 shows a process flow diagram illustrating operations in a method for in-feature planarization of molybdenum-containing material via nitridation.

[0034] Figure 7 shows a process flow diagram illustrating operations for treating titanium nitride prior to depositing molybdenum-containing material.

[0035] Figures 8, 9A, and 9B show examples of plasma process apparatus and systems that may be used to practice the methods described herein in accordance with certain disclosed embodiments.

[0036] Figure 10 shows an example of the apparatus with a remote plasma source that may be used to perform the methods described herein in accordance with certain disclosed embodiments.

[0037] FIG. 11 depicts a cross-sectional side view of an example apparatus in accordance with disclosed embodiments.DETAILED DESCRIPTION

[0038] In the following descriptions, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practicedwithout some or all of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0039] Provided herein are methods for in-feature planarization of molybdenum (Mo) deposition. The methods involves oxidizing or nitriding a portion of molybdenum-containing material in spaced-apart features to form molybdenum oxide or molybdenum nitride, selectively etching the molybdenum oxide or nitride with respect to the remaining underlying molybdenum-containing material. When used, the methods may reduce line-to-line (LtL) variation, roughness, molybdenum faceting, and line bending of the molybdenum feature fill. Moreover, when used, the methods may increase the grain size of the molybdenum, thereby reducing the resistance. The methods described herein may be used for logic and memory applications and may be used to deposit molybdenum in a semiconductor substrate with features such as vias, wordlines such as dynamic random-access memory (DRAM) buried wordline (bWL), and trenches. The method may be used to deposit molybdenum to fill features as liner layer and / or fill features.

[0040] The methods described herein may be used with other gap fill techniques for example, before or after a selective, bottom-up molybdenum deposition process. The methods may be used as a pre-and / or post-treatment of the deposited molybdenum.

[0041] In some implementations, the methods may be used on a molybdenum deposited on metalcontaining surfaces of a feature, where the metal-containing surfaces may be a titanium nitride or molybdenum liner plug at the feature bottom. In some embodiments, the metal-containing surfaces contain metals such as cobalt (Co), ruthenium (Ru), copper (Cu), tungsten (W), molybdenum (Mo), nickel (Ni), iridium (Ir), rhodium (Rh), tantalum (Ta), and titanium (Ti). In some embodiments, the metal -containing surface is an elemental metal surface. There may be some oxide formed on the metal-containing surface due to exposure to moisture. In some embodiments, the metal-containing surface is a metal compound with examples including a titanium nitride (TiN), molybdenum nitride (MoNx), tungsten nitride (WN), tungsten carbon nitride (WCxNy), a titanium aluminum carbide (TiAlxCy), titanium silicide (TiSi2), or tantalum nitride (TaN) surface.

[0042] Figures 1A and IB are schematic examples of material stacks that include Mo layers according to various embodiments. Figures lAand IB illustrates the order of materials in examples of particular stacks and may be used with any appropriate architecture application, as described further below with respect to Figures 2 A - 2L. Figure 1 A shows a first material stack 111 featuring a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 may be a siliconor other semiconductor wafer, e.g., a 200-nm wafer, a 300-nm wafer, or a 450-nm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semiconductive materials deposited thereon. In some embodiments, the substrate 102 may be or include silicon (Si) or silicon germanium (SiGe). The method may also be applied to form metallization stack structures on other substrates, such as glass, plastic, and the like.

[0043] The stack 111 has a dielectric layer 104 on the substrate 102. The dielectric layer 104 may be deposited directly on a semiconductor surface (e.g., a Si or SiGe surface) of the substrate 102, or there may be any number of intervening layers. For example, the substrate 102 may include any number of layers deposited in various arrangements on a semiconductor substrate.

[0044] Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, with specific examples including doped or undoped layers of silicon nitride (SiN), silicon dioxide (SiOr), and aluminum oxide (AI2O3). The stack 111 has a layer 106 disposed between the molybdenum layer 108 and the dielectric layer 104. The layer 106 may be a diffusion barrier and / or adhesion layer, for example. A diffusion barrier is a layer that prevents the diffusion of species between layers. An adhesion layer is a layer that promotes adhesion of layer to an underlying layer. Examples of diffusion barrier and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten (W), tungsten nitride (WN), and tungsten carbon nitride (WCN). The molybdenum layer 108 is the main conductor of the structure. In some embodiments, the molybdenum layer 108 may or may not include a molybdenum nucleation layer. In some embodiments, molybdenum layer is an amorphous molybdenum-containing layer. In the depicted example of Figure 1 A, the molybdenum layer 108 is deposited directly on the layer 106. In other embodiments (not depicted), the molybdenum layer 108 may be deposited on a separate layer, such as a growth initiation layer that includes another material, such as a tungsten (W) or W-containing growth initiation layer. The growth initiation layer may be used to facilitate nucleation and growth of molybdenum layer 108.

[0045] Figure IB shows another example of a stack 121. In this example, the stack 121 includes the substrate 102, dielectric layer 104, with molybdenum layer 208 deposited directly on the dielectric layer 104, without an intervening diffusion barrier or adhesion layer. The molybdenum layer 108 is as described with respect to Figure 1A, by using molybdenum as the main conductor, low-resistivity thin films can be obtained. Examples of low-resistivity thin films include films with resistivity less than 40 u m-cm at 60 angstroms thickness and less than 15 uQm-cm at 200 angstroms thickness.

[0046] In some embodiments, a stack (not shown) may include a substrate, a conductive layer, and a molybdenum layer deposited onto the conductive layer. As used herein, a conductive layer is a layer having a conductivity of at least 104 1-cmIat room temperature. Examples include molybdenum on a metal layer (e.g., a W layer, or another Mo layer). 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 metal nitride layer (e.g., TiN, WN, or MoN). In still some other embodiments of stack (not shown), the stack may include a substrate and a molybdenum layer deposited directly on the substrate, including directly on a semiconductor surface, on a dielectric surface, or a conductive surface. Figures 1 A and IB illustrates examples of the order of materials in a particular stack and may be used with any appropriate architecture and applications, with examples described further below with respect to Figures 2A - 2L.

[0047] The methods described herein are performed on a substrate that may be housed in a chamber. The substrate may be a silicon or other semiconductor wafer, including wafers having one or more layers of materials, such as dielectric, conducting, or semiconducting material deposited thereon. The methods are not limited to semiconductor substrates and may be performed to fill any features with molybdenum.

[0048] Substrates may have features such as vias or contact holes, which may be characterized by one or more narrow and / or re-entrant openings, constrictions within the feature, and high aspect ratios. A feature may be formed in one or more of the above-described stacks or layers within a stack. For example, the features may be formed at least partially in a dielectric layer. In some embodiments, a feature may have an aspect ratio of at least about 2:1, at least about 4:1, at least about 6: 1, at least about 10:1, at least about 25:1, or higher. One example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate.

[0049] Figure 2A depicts a schematic example of a DRAM architecture, including a Mo buried wordline (bWL) 208 in a silicon substrate 202. The Mo bWL is formed in a trench etched in the silicon substrate 202. Lining the trench is a conformal barrier layer 206 and an insulating layer 204. The conformal barrier layer 206 is disposed between the insulating layer 204 and the silicon substrate 202. In this example, the insulating layer 204 may be a gate oxide layer formed from a high-k dielectric material such as silicon oxide or silicon nitride material. In some embodiments disclosed herein, the conformal barrier layer 206 is TiN or tungsten-containing layer, such as WN or WCN layer. In some embodiments, a conformal tungsten-containing growth initiation layer (not shown) may be present between the conformal barrier layer 206 and the molybdenum bWL 208.Alternatively, the molybdenum bWL 208 may be deposited directly on a TiN or other diffusion barrier. In some embodiments, one or both of layers 204 and 206 is not present.

[0050] The bWL structure shown in Figure 2A is one example of an architecture that includes a molybdenum fill layer. During fabrication of the WL, molybdenum is deposited into a feature that may be defined by an etched recess in the silicon substrate 204 that is conformally lined with layers 206 and / or 204, if present.

[0051] Figures 2B - 2H are additional schematic examples of various structures into which molybdenum may be deposited in accordance with disclosed embodiments. Figure 2B shows an example of a cross-sectional depiction of a vertical feature 201 to be filled with Mo. The feature can include a feature hole 205 in a silicon substrate 202. The feature hole 205 may have an underlayer 203 lining the sidewall or interior of the feature hole 205 and may form the interior surfaces. The feature hole 205 or other features may have a dimension near the opening, e.g., an opening diameter or line width of between about 10 nm to 500 nm, for example, between about 25 nm to about 300 nm. The feature hole 205 can 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 that extends through the length of the feature, with vertically oriented feature having vertical axes and horizontally oriented feature having horizontal axes. The underlayer 203 can be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of underlayers can include dielectric layers and conducting layers. Examples of dielectric materials include oxides, such as SiCF, AhOy nitrides, such as SiN; carbides, such as nitrogen-doped silicon carbide (NDC) and oxygen-doped silicon carbide (ODC); and low k dielectrics, such as carbon doped SiCh. In particular implementations, an underlayer can be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the underlayer is tungsten- free. In some embodiments, the underlayer is molybdenum-free.

[0052] In some embodiments, features are wordline features in a 3D NAND structure. For example, a substrate may include a wordline structure having an arbitrary number of wordlines (e.g., 50 to 450) with vertical channels at least 200 A deep. Examples of wordline features are described further below. Another example of a feature is a trench in a substrate or layer. Features may be of any depth. In various embodiments, the features may have an underlayer, such as a barrier layer or adhesion layer. Non-limiting examples of underlayers include dielectric layers and conducting layers, e.g., silicon oxides, silicon nitrides, silicon carbides, metal oxides, metal nitrides, metal carbides, and metal layers.

[0053] Figure 2C shows an example of a vertical feature 201 that has a re-entrant profile. A reentrant profile is a profile that narrows from the bottom, closed-end, or interior of the feature to the feature opening. According to various implementations, the profile may narrow gradually and / or include an overhang at the feature opening. Figure 2C shows an example of the latter, with an underlayer 213 lining the sidewall or interior surfaces of the feature hole 205. Similar to Figure 2B, underlayer 213 can be a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of underlayers can include dielectric layers and conducting layers. The underlayer 213 forms an overhang 215 such that the underlayer 13 is thicker near the opening of the vertical feature 201 than inside the vertical feature 201.

[0054] In some implementations, features have one or more constrictions within the feature may be filled. Figure 2D shows examples of views of various filled features having constrictions. Each of the examples (a), (b), and (c) in Figure 2D includes a constriction 209 at a midpoint within the feature. The constriction 209 can be, for example, between about 15 nm - 20 nm wide. Constrictions can cause pinch off during the deposition of molybdenum in the feature using conventional techniques, with deposited metal blocking further deposition past the constriction before that portion of the feature is filled, resulting in voids in the feature. Example (b) further includes an overhang 215 (such as, a liner / barrier overhand) at the feature opening. Such an overhang could also be a potential pinch-off point. Example (c) includes a constriction 212 further away from the field region than the overhang 215 in example (b).

[0055] Horizontal features, such as in 3D memory structures, can also be filled. Figure 2E shows an example of a horizontal feature 250 that includes a constriction 251. For example, horizontal feature 250 may be a wordline in a 3D NAND (also referred to as vertical NAND or VNAND) structure. In some implementations, the constrictions can be due to the presence of pillars in a 3D NAND or other structure. Figure 2F presents a cross-sectional side view of a 3D NAND structure 210 (formed on a silicon substrate 202) having 3D NAND stack (left 225 and right 226), central vertical structure 230, and the plurality of stacked horizontal wordline features 220 with opening 222 on opposite sidewalls 240 of central vertical structure 230. Note that Figure 2F displays two “stacks” of the exhibited 3D NAND structure 210, which together form the “trench-like” central vertical structure 230. However, in certain embodiments, there may be more than two such stacks arranged in sequence and running spatially parallel to one another, the gap between each adjacent pair of s stacks forming a central vertical structure 230, like that explicitly illustrated in Figure 2F. In this embodiment, the horizontal wordline features 220 are 2D memory wordline features that are fluidically accessible from the central vertical structure 230 through the openings 222.Although not explicitly indicated in the figure, the horizontal wordline feature 220 present in both the 3D NAND stacks 225 and 226 shown in Figure 2F (i.e., the left 3D NAND stack 225 and the right 3D NAND stack 226) are also accessible from the other sides of the stacks (far left and far right, respectively) through similar vertical structures formed by additional 3D NAND stacks (to the far left and far right, but now shown). Each 3D NAND stack 225, 226 contains a stack of wordline features that are fluidically accessible from both sides of the 3D NAND stack through a central vertical structure 230. In the particular example schematically illustrated in Figure 2F, each 3D NAND stack contains 6 pairs of stacked wordlines. However, 3D NAND memory layout may contain any number of vertically stacked pairs of wordlines.

[0056] The wordline features in a 3D NAND stack can be formed by depositing an alternating stack of silicon oxide and silicon nitride layers, and then selectively removing the nitride layers leaving a stack of oxides layers having gaps between them. These gaps are the wordline features. Any number of wordlines maybe vertically stacked in such a 3D NAND structure so long as there is a technique for forming them available, as well as a technique available to successfully accomplish (substantially) void-free fills of the vertical features. Thus, for example, a VNAND stack may include between 2 and 512 horizontal wordline features, between 2 and 256 horizontal wordline features, between 8 and 128 horizontal wordline features, or between 16 and 64 wordline features, and so forth (the listed ranges understood to include either recited endpoints).

[0057] Figure 2G presents a cross-sectional top-down view of the same 3D NAND structure 210 shown in the side view in Figure 2F with the cross-section taken through the horizontal section 260 as indicated by the dashed horizontal line in Figure 2F. The cross-section of Figure 2G illustrates several rows of pillars 255, which are shown in Figure 2F to run vertically from the base of the substrate 202 to the top of the 3D NAND structure 210. In some embodiments, the pillars 255 are formed from a polysilicon material and are structurally and functionally significant to the 3D NAND structure 210. In some embodiments, such polysilicon pillars may serve as gate electrodes for stacked memory cells formed within the pillars. The top- view of Figure 2G illustrates that the pillars 255 form constrictions in the opening 222 to wordline feature 220. Fluidic accessibility of wordline features 220 from the central vertical structure 230 via opening 222 (as indicated by the arrows in Figure 2G) is inhibited by pillars 255. In some embodiments, the size of the horizontal gap between adjacent polysilicon pillars is between about 1 and 20 nm. This reduction in fluidic accessibility increases the difficulty of uniformly filling wordline features 220 with the material. The structure of the wordline features 220 and the challenges of uniformly filling the with molybdenum material due to the presence of pillars 255 is further illustrated in Figures 2H, 21, and 2J.

[0058] Figure 2H exhibits a vertical cut through a 3D NAND structure similar to that shown in figure 2F, but here focused on a single pair of wordline features 220 and additionally schematically illustrating a fill process which resulted in the formation of a void 275 in the filled wordline feature 220. Figure 21. also schematically illustrates void 275, but in this figure illustrated via a horizontal cut through pillars 255, similar to the horizontal cut exhibited in Figure 2G. Figure 2J illustrates the accumulation of molybdenum material around the constriction-forming pillars 255, the accumulation resulting in the pinch-off of opening 222, so that no additional molybdenum material can be deposited in the region of voids 275. Apparent from Figures 2H and 21 is that void-free molybdenum fill relies on migration of sufficient quantities of deposition precursor down through central vertical structure 230, through openings 222, past the constricting pillars 255, and into the furthest reaches of the wordline feature 220, prior to the accumulated deposition of molybdenum around pillars 255 causing a pinch-off of the openings 222 and preventing further precursor migration into wordline features 220. Similarly, Figure 2J exhibits a single wordline feature 220 viewed cross-sectionally from above and illustrates how a generally conformal deposition of molybdenum material begins to pinch-off the interior of wordline feature 220 due to the fact that the significant width of pillars 255 acts to particularly block, and / or narrow, and / or constrict what would otherwise be an open path through wordline feature 220. (It should be noted that the example in Figure 2J can be understood as a 2D rendering of the 3D features of the structure of the pillar constrictions shown in Figure 31, thus illustrating constrictions that would be seen in plan view rather than in a cross-sectional view.)

[0059] Three-dimensional structures may need longer and / or more concentrated exposure to precursors to allow the innermost and bottommost areas to be filled. Three-dimensional structures can be particularly challenging when employing molybdenum halide and / or molybdenum oxyhalide precursors because of their proclivity to etch, with longer and more concentrated exposure allowing for more etch as parts of the structure.

[0060] Figures 2K and 2L show examples of asymmetric trench structure DRAM bWL. Some fill processes for DRAM bWL trenches can distort the trenches such that the final trench width and resistance Rs are significantly non-uniform. Figure 2K shows an unfilled feature 261 and filled feature 265 that exhibits the line bending after fill. In this example, the features are a narrow asymmetric trench structure DRAM bWL. As shown, multiple 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 and about 60 nm or between about 20 nm and 40 nm. The pitch is defined as the distance between the middle axis of one feature to the middle axis of an adjacent feature. The unfilled feature 261 may be generally V-shaped, as shown in feature 283, havingsloped sidewalls where the width of the feature narrows from the top of the feature to the bottom of the feature. The features widen from the feature bottom 273b to the feature top 273a. After some fill operations, line bending may be observed within the filled feature 265. In some situations, a cohesive force between opposing surfaces of a trench pulls the trench sides together, as depicted by arrows 267. The phenomenon is illustrated in Figure 2L and may be characterized as “zipping up” the feature. As feature 283 is filled, more force is exerted from the center axis 299 of feature 283, causing line bending. For example, molybdenum may be deposited on the sidewalls of the feature 283. Deposited molybdenum 284a and 284b on sidewalls of feature 283 thereby interact in close proximity, where molybdenum-molybdenum bond radius r is small, thereby causing cohesive interatomic forces between the smooth growing surfaces of molybdenum and pulling the sidewalls together, thereby causing line bending.

[0061] Figure 3 depicts yet another example of a feature 300 according to various embodiments. Figure 3 depicts an example of a feature 300 according to various embodiments. The feature 300 includes a bottom surface 302 and one or more sidewall surfaces 304. An etch stop layer (ESL) 306 is also shown. The bottom surface 302 may be a metal-containing surface. The structure 300 is filled with molybdenum to form a Mo interconnect 308 that provides an electrical connection to the underlying contact.

[0062] In some embodiments, the bottom surface 302 is a metal-containing surface. The metalcontaining surface may contain any appropriate metal, such as cobalt (Co), ruthenium (Ru), copper (Cu), tungsten (W), molybdenum (Mo), nickel (Ni), iridium (Ir), rhodium (Rh), tantalum (Ta), and titanium (Ti). In some embodiments, the metal-containing surface 302 is an elemental metal surface. There may be some oxide formed on the metal-containing surface due to exposure to moisture. In some embodiments, the metal-containing surface is a metal compound with examples including a titanium nitride (TiN), molybdenum nitride (MoNx), tungsten nitride (WN), tungsten carbon nitride (WCxNy), a titanium aluminum carbide (TiAlxCy), titanium silicide (TiSi ), or tantalum nitride (TaN) surface. These surfaces may exhibit selectivity with respect to dielectric oxides.

[0063] As used herein, oxide surfaces include alkoxides such as tetraethyl orthosilicate (TEOS), fluorosilicate glass (FSG), flowable oxides, spin-on-glasses, carbon doped oxides, etc. In some embodiments, the oxide surface is a silicon-based oxide with examples given above.

[0064] The one or more sidewall surfaces 304 are dielectric surfaces. Such surfaces include alkoxides such as poly(2-ethyl-2-oxazoline) (PEOX) and silicon-based oxides including tetraethyl orthosilicate (TEOS) oxide, flowable silicon-based oxides, carbon doped silicon-based oxides,SiO2 etc. These surfaces may be part of the main dielectric layer surrounding the feature. Selectivity refers to the preference in deposition on a metal surface, such as Co, W or Cu surface relative to a dielectric surface. It may be quantified as a ratio of deposition rates or as a ratio of deposition thicknesses after a certain number of deposition cycles.

[0065] In some embodiments, the sidewall surfaces may be nitrides (e.g., SixNy) rather than oxides. The nitrides may be silicon-based nitrides or silicon-based oxynitrides. Selectivity of Mo film deposition on elemental metal with respect to nitrides is similar to that with respect to oxides.

[0066] Selectivity of Mo film deposition on metal nitrides may also be obtained if the sidewall surfaces are oxides. For example, Mo may be selectively deposited on TaN or TiN with respect to a silicon oxide surface. In some embodiments, Mo is selectively deposited on TaN or TiN with respect to the silicon oxide surface by using M0CI5 precursor.

[0067] The Mo interconnect 308 may be part of any appropriate part of a partially fabricated semiconductor device, including a source / drain (S / D) connection, a middle of the line (MOL) structure or a back end of line (BEOL) structure.

[0068] Figure 4 shows example embodiments of patterned features in which selective deposition of a Mo film may be performed. A patterned feature may be a via or a trench or other appropriate feature formed as a result of a patterning operation in a dielectric layer. Feature 410 shows an example of a patterned feature having an open profile that expands gradually from the bottom of the feature to the feature opening 414.

[0069] Feature 420 shows an example of a patterned feature having a re-entrant profile that narrows from the bottom of the feature to the feature opening 414. A re-entrant profile may also include an overhang at the feature opening 414. Feature 430 shows a feature with a metal undercut profile. According to various implementations, the profile has the metal-containing surface below the sidewall base 418 of the feature 430. There may be voids between the bottom surface 402 and the sidewall base 418. In each of the above profiles, the bottom surface 402 may be a metalcontaining surface, for example a metal or metal nitride surface. There may be oxide 416 formed on the bottom surface 402 of the metal or metal nitride.

[0070] Provided below are methods of planarizing molybdenum-containing material in a feature. The methods described herein may be used to deposit molybdenum-containing material on a substrate. The substrate may be any featured substrate, for example, DRAM bWL. In some embodiments, molybdenum-containing material is deposited on a material stack and / or in a featured substrate, for example, as shown in the examples of Figures 1A, IB, and Figures 2A- 2L.When used, the methods described herein may reduce line-to-line (LtL) variation, molybdenum faceting, and line bending of the molybdenum feature fill. The methods described herein may be used to achieve in-feature planarization (IFP). Figure 5A provides an illustrative example of infeature planarization according to the method described herein. As depicted in Figure 5A, featured substrates 511 may have a plurality of features with non-uniform molybdenum-containing material 515 therein. The featured substrates 51 1 may undergo a surface modification process 520, for example, oxidation or nitridation, to convert a portion of the molybdenum-containing material to molybdenum oxide or molybdenum nitride 516, depending on the types of surface modification chemistry used. The molybdenum oxides or molybdenum nitride 516 may be selectively etched 530 to reveal uniform molybdenum-containing material 527 with reduced line-to-line variation.

[0071] In the example of Figure 5 A, the substrate 511 has a plurality of features spaced apart, each feature has a feature opening 513 and the molybdenum-containing material 515 deposited therein. Each feature is also characterized by a depth (e.g., 517 and 519) from the feature opening 513 to the surface of the molybdenum-containing material therein. This depth varies from feature-to- feature. For example, in Figure 5A, two depths, 517 and 519, are shown. As depicted in Figure 5A, these depths, 517 and 519, are different, where 519 is greater than 517.

[0072] Advantages of the methods described herein include a reduction of molybdenum precursor consumption compared to other methods for molybdenum feature fill and improved selectivity or increased throughput of molybdenum deposition. Another advantage of the method is that when practiced, the grain size of the molybdenum may be larger than that without performing the method. In one example, without performing the methods, there may be about 45 molybdenum grains which is reduced to about 30 molybdenum grains after performing the method. When practiced, the methods can improve the resistivity of the resultant film. For example, in 70 A thick molybdenum films, without the in-feature planarization process outlined here, the resistivity may be about 39 uQm-cm compared to about 27.5 uQm-cm after performing the process. The reduced number of grains, when the method is practiced, may be a contributing factor for lower resistivity.

[0073] Figure 5B is a process flow diagram illustrating example operations in a method for infeature planarization of molybdenum-containing material. Process 500 begins with operation 501, in which a substrate having a layer of molybdenum-containing material deposited therein is provided. In operation 503, at least a portion of the molybdenum-containing material is oxidized, thereby forming a layer of molybdenum oxide. In operation 505, the molybdenum oxide is selectively etched.

[0074] Referring to operation 501, in some embodiments, the substrate may be a featured substrate. For example, the substrate has a plurality of features spaced apart, each feature may have a feature opening and the molybdenum-containing material deposited therein, and each feature may have a depth from the feature opening to a surface of the molybdenum-containing material therein. In various embodiments, each feature may be partially filled with the molybdenum- containing material.

[0075] In some embodiments, feature-to-feature depth is characterized by a feature-to-feature depth non-uniformity. Feature-to-feature depth non- uniformity refers to features having different feature depths (from each feature opening to a surface of molybdenum-containing material inside each feature) or having variation in feature depths between different features. Feature depth can be determined from a scanning electron microscope (SEM) or transmission electron microscope (TEM) image of the feature (or featured substrate) by evaluating the distance between the feature opening and the surface of the molybdenum-containing material for each feature.

[0076] In some embodiments, the molybdenum-containing material is pure molybdenum. Pure molybdenum refers to molybdenum having no more than trace amounts of other materials. Pure molybdenum contains at least 95% molybdenum, at least 98% molybdenum, at least 99% molybdenum, or at least 99.9% molybdenum. In some embodiments, the molybdenum-containing material may contain some amounts of other species, such as oxygen, chlorine, nitrogen, etc.

[0077] In some embodiments, the molybdenum-containing material may include impurities that can hinder the conductivity. For example, impurities may be oxygen contaminants, and oxygen contaminants may be present within the molybdenum-containing material. In some embodiments, impurities may be molybdenum oxide, molybdenum nitride, and / or molybdenum oxynitride. For example, molybdenum oxide and / or nitride may be present as a layer on top and / or on the surface of the molybdenum-containing material.

[0078] In some embodiments, the molybdenum-containing material may be deposited inside each feature via a bottom-up or selective bottom-up molybdenum deposition process. Molybdenum- containing materials may be deposited using any suitable molybdenum deposition methods.

[0079] In some embodiments, the molybdenum-containing layer is deposited by reacting a molybdenum-containing precursor (also referred to as a molybdenum precursor) with a coreactant. In some cases, a co-reactant is a reducing agent. For example, molybdenum-containing material may be deposited by exposing the substrate to a molybdenum-containing precursor, such as molybdenum halides, and reducing the molybdenum halide with hydrogen. In someembodiments, molybdenum halides may be molybdenum chloride such as molybdenum pentachloride (M0CI5) or molybdenum oxyhalides such as molybdenum dichloride dioxide (MoO- 2CI2).

[0080] The molybdenum-containing material may be deposited by implementing various deposition techniques. For example, thermal or plasma-atomic layer deposition (ALD) or chemical vapor deposition techniques (CVD) may be used. The molybdenum-containing material may be deposited using Mo02C12 and / or MoC15 or using any other suitable molybdenum-containing precursor. In some embodiments, the molybdenum-containing material may be deposited with a reducing agent (e.g., H2). Methods may include surface treatment using a molybdenum halide compound, which may be the same or a different compound used in deposition. Further details on molybdenum deposition are provided below including other molybdenum precursors.

[0081] In some embodiments, molybdenum-containing material is selectively deposited on a substrate or into a feature. Selective deposition refers to a preferential deposition on a first material with respect to a second material. In some embodiments, molybdenum-containing material is selectively deposited and grown on a metal material relative to a dielectric material. In some embodiments, molybdenum-containing material is selectively deposited and grown on a metal or metal nitride material relative to an oxide material. For example, molybdenum may be preferentially deposited on a metal or metal nitride on a bottom portion of the feature surface (e.g., a Mo plug or TiN plug) relative to oxide sidewalls.

[0082] In some embodiments, molybdenum may be preferentially deposited on a barrier material (e.g., TiN) or a metal liner (e.g., Mo liner). While the example embodiments herein are described in the context of a TiN plug, any other suitable metal liner or plug may be used. A liner is a thin layer of material that conformally coats at least a portion of the feature (e.g., feature sidewalls), in contrast, a plug is formed primarily on the feature bottom and may be thicker than the liner.

[0083] In selective deposition, molybdenum-containing material is deposited into the feature and grows on the TiN plug but does not grow (or grow to a lesser extent) on the silicon oxide sidewall surfaces. Additional descriptions of the selective molybdenum deposition are provided below.

[0084] In some embodiments, selective deposition of the molybdenum-containing material in a feature involves first depositing TiN at the feature bottom and etching the TiN from the feature top and sidewalls to achieve TiN with desired thickness, and selectively depositing the molybdenum- containing material.

[0085] One example of selective bottom-up deposition of the molybdenum-containing material in a feature involves forming a TiN plug at the feature bottom and selectively depositing molybdenum-containing material thereon by reacting M0CI5 with H2 via thermal ALD.

[0086] In various applications, such as DRAM bWL, line bending induced by the metal feature fill is a challenge as the pitch of the wordline shrinks. Line bending is a phenomenon found in, for example, substrates having multiple features with narrow pitch, or in substrates with multiple high aspect ratio features adjacent to one another. Line bending in DRAM bWL during the feature fill with metal (e.g., molybdenum) may be caused by grain boundary merging (which may be referred to as a “zipping” mechanism). When the grain boundaries are formed, the metal-metal bonding between adjacent metal surfaces (such as the grown molybdenum film on the sidewalls of a feature) causes strain that leads to the bending of the silicon oxides and / or silicon nitride fins (lines) separating the bWL. Atomic layer deposition and CVD fill techniques can result in severe bending of the bWL structures. This line bending may cause metal recess non-uniformity and contact landing issues in downstream processes, which result in DRAM yield loss.

[0087] Some benefits of using the selective bottom-up deposition method include a reduction of line bending compared to other conformal deposition techniques. In addition to addressing the line-bending issues, bottom-up deposition can achieve larger molybdenum grain growth inside the feature in some implementations. This, in turn, can improve the wordline resistance.

[0088] While the bottom-up deposition method can offer some advantages, there are challenges associated with the method. One challenge associated with the method is that the plug, such as the TiN plug, can exhibit a substantial variation in its surface. The variation in the surface of the plug may be, for example, surface roughness across the plurality of features fill, line-to-line variation amongst the features, and even within the feature variation (i.e., in-feature roughness). This variation in the plug can lead to variations in a molybdenum-containing material thereon. The line- to-line variation or in-line variation / roughness of the TiN plug poses significant challenges for the subsequent integration steps (e.g., DRAM bWL) and can lead to poor performances / yields of the resulting device.

[0089] In some embodiments, the TiN plug can display line bending before the Mo deposition. This can lead to non-uniform deposition of the Mo material, which can worsen the line bending as the thickness of the Mo material becomes larger.

[0090] Another challenge in bottom-up molybdenum deposition is faceting, where different crystallites or nucleates having different orientations are formed or deposited on a substrate.Faceting increases the surface area of the deposited molybdenum-containing material. In some implementations, the molybdenum deposition process can introduce variation, in addition to the aforementioned variations resulting from the plug. For instance, as the thickness of the Mo grows, molybdenum may begin to exhibit faceting. Molybdenum faceting may be present when the large grain (such as single grain) molybdenum is present within the wordline and can display facets on the molybdenum surfaces. In some cases, Mo faceting can worsen the line-bending.

[0091] Another challenge in the bottom-up molybdenum deposition process is selectivity loss. After repeated molybdenum deposition cycles, in some embodiments, undesired nucleate may appear on the feature top and / or the feature sidewalls. Here, undesired nucleates refer to a nucleate that is formed in places other than the feature bottom. The undesired nucleates can reduce the selectivity of the molybdenum deposition and interrupt the bottom-up growth process or cause leakage between wordlines. In some cases, undesired nucleates may be molybdenum nucleates that are formed in places other than the feature bottom, such as features sidewalls, near or at feature openings.

[0092] In some embodiments, selectivity loss may be introduced due to the plug formation process. For example, during the TiN plug formation, TiN may not be removed from the oxide feature sidewalls, oxide feature sidewalls may be etched during the process, or byproducts (such as fluorine or chlorine) may be present within the feature. This can lead to a decrease in molybdenum selectivity, and molybdenum may begin to nucleate on the oxides.

[0093] In addition to or instead of optimizing the molybdenum deposition conditions, the process 500 described with reference to Figure 5B may be used to achieve in-feature planarization (IFP).

[0094] After providing the substrate in operation 501, in operation 503, at least a portion of the molybdenum-containing material is oxidized, thereby forming a layer of molybdenum oxide. In operation 503, oxidizing the molybdenum-containing material may result in surface modification. The oxidation process may be sensitive to the surface area, where a feature having a larger molybdenum surface area (due to faceting, roughness, in-feature, and / or line-to-line variation) can lead to a larger extent of oxidation of the molybdenum-containing material. In some embodiments, operation 503 oxidizes a portion of a molybdenum-containing material to form a molybdenum oxide (e.g., MoOs and / or MoOz).

[0095] In some implementations, operation 503 can improve molybdenum faceting on the surface and / or the sidewalls of the feature. This may be because the molybdenum faceting leads to increased surface area, and the oxidation process can be sensitive to the surface area.

[0096] In some embodiments, operation 503 may lead to the smoothening of the surface. This may be a result of volume expansion upon oxidation of the molybdenum-containing material. In some embodiments, the molybdenum oxides can have a larger volume compared to molybdenum- containing materials. In some cases, regions with larger surface area (e.g., rough surfaces) may experience larger volume expansion as the extent of the oxidation process is greater in such regions.

[0097] In some embodiments, operation 503 may reduce the extent of line-to-line variation compared to before performing operation 503. For example, line-to-line variation prior to performing operation 503 may be about 1.5 nm, 1.7 nm, or 2.0 nm, or between 1.5 - 2.0 nm, whereas line-to-line variation after performing operation 503 may be about 1 nm, about 1.2 nm, about 1.5 nm, about 1.6 nm, between 1 nm and 2 nm. (In the description herein, “line-to-line” variation, ‘line-to-line’ non-uniformity, or ‘line-to-line’ depth non-uniformity is used interchangeably with “feature-to-feature” variation, ‘feature-to-feature’ non-uniformity, or ‘feature-to-feature’ depth non-uniformity).

[0098] In cases where undesired nucleates are present on the sidewalls of the feature or near the feature top, operation 503 may oxidize these undesired nucleates and form oxides such as molybdenum oxides.

[0099] In some embodiments, operation 503 involves exposing the featured substrate to an oxy gen-containing plasma. In some embodiments, oxygen-containing plasma may be generated from oxygen gas (O2), but any other suitable oxygen-containing plasma may be used. In some implementations, oxygen-containing plasma may be generated from a mixture of gases. For example, oxygen-containing plasma may be generated from a mixture containing one or more inert gases such as hydrogen (H2), argon (Ar), helium, and combinations thereof. In some embodiments, an oxygen-containing plasma is generated from a mixture of oxygen gas with hydrogen gas. In some embodiments, an oxygen-containing plasma is generated from a mixture of oxygen gas with argon.

[0100] In some embodiments, the process gas used in operation 503 may be at least 20 % oxygen (O2), at least 30% oxygen, 20 - 30% oxygen, 20 - 50% oxygen, or 100% oxygen. In some cases, the ratio of oxygen gas may influence the oxidation depth. When a higher amount of oxygen is present in the process gas, the oxidation depth may be larger. For example, when the process gas contains oxygen and hydrogen, a higher concentration of oxygen can lead to a greater extent of oxidation within the feature compared to the process gas that contains a lower concentration of oxygen.

[0101] In some embodiments, an oxygen-containing plasma is ignited using a capacitively coupled plasma generator. In some embodiments, an oxy gen-containing plasma is ignited using an inductively coupled plasma generator. In some cases, oxy gen-containing plasma is generated in a remote chamber.

[0102] In some embodiments, at each station, an oxygen-containing plasma is ignited using a power between 150 - 1000 W, at least 150 W, at least 200 W, at least 500W, at least 750 W, or at least 1000W.

[0103] In some implementations, operation 503 involves expositing the featured substrate to a thermal soaking process with oxygen-containing soak gas. Examples of oxygen-containing soak gases include but are not limited to, ozone, oxygen gas, water, or combinations thereof. Any suitable oxygen-containing soak gas may be used in operation 503. In some embodiments, operation 503 involves exposing the featured substrate to an ozone-soak gas. In some embodiments, operation 03 involves exposing the featured substrate to water-soak gas.

[0104] In some embodiments, operation 503 converts a portion of the molybdenum-containing material to form a molybdenum oxide. In some embodiments, operation 503 oxidizes the top 6 - 10 nm of the molybdenum-containing layer to form molybdenum oxide. In some cases, operation 503 oxidizes at least 5 nm, at least 6 nm, at least 10 nm, at least 15 nm, at least 20 nm, or 5 - 25 nm or 5 - 27 nm of the molybdenum-containing layer.

[0105] In some embodiments, the molybdenum oxide may be formed to a thickness between 6 - 10 nm, between 5 - 15 nm, at least 5 nm, at least 6 nm, at least 10 nm, at least 15 nm, at least 20 nm, or 5 - 25 nm, between 20 - 27 nm, or 5 - 27 nm.

[0106] In some embodiments, line-to-line variation of the molybdenum oxide thicknesses may be about 0.5 nm, about Inm, about 1.1 nm, about 1.3nm, about 1.5 nm, about 2 nm, about 3 nm, about 3.2 nm, 0.5 - 1.5 nm, 1 - 2 nm, 1 - 3 nm, or 1 - 3.5 nm.

[0107] In some embodiments, operation 503 may reduce the line-to-line variation by at least 0.2 nm, at least 0.3 nm, at least 0.4 nm, at least 0.6 nm, at least 0.7 nm, or between 0.2 - 1 nm. For example, the line-to-line variation prior to performing operation 503 may greater than 1.6 nm, and the line-to-line variation after performing operation 503 is less than 1.2 nm.

[0108] In some embodiments, the oxidation process in operation 503 is a self-limiting process. This is because diffusion of the oxygens may be limited at larger molybdenum oxide thickness. For example, after the featured substrate is exposed to an oxygen-containing oxidant for asufficient duration or under appropriate operating conditions, the thickness of the molybdenum oxide reaches a threshold where the diffusion of oxygen may be prevented.

[0109] In various implementations, operation 503 may be performed at various operating conditions. Operating conditions may be tuned to influence the thickness of the molybdenum oxide formed during operation 503. Tuning the operating conditions may allow control over the depth in which the oxygen radical or ions may diffuse within the feature. Examples of the tunable operating conditions include, but are not limited to, gas flow rate, the ratio of oxygen (e.g., % volume), temperature, pressure, dose time of the gases, and plasma generation conditions such as power, and bias.

[0110] Operation 503 may be performed at various temperatures. For example, operation 503 may be performed at temperatures between 225 - 400 °C, such as 225 °C, 300 °C, 350 °C, and 360 °C. In some embodiments, operation 503 may be performed at temperatures above 400 °C, such as 425 °C or 450°C.

[0111] Operation 503 may be performed at various pressures. For example, operation 503 may be performed at pressures between 0.4 - 10 torr, at least 0.5 torr, at least 1 torr, at least 1.5 torr, at least 3 torr, at least 5 torr, or at least 10 torr. In some embodiments, operation 503 is performed at 1.5 torr, 3 torr, or 10 torr.

[0112] Operation 503 may be performed where gases are introduced at various durations of dose times. The dose time of each gas may be used to the ratio of each gas (e.g., 20 - 30% oxygen in process gas). In operation 503, oxygen and / or other process gases (e.g., hydrogen or argon gases) may be delivered for a dose time ranging from 1.5 to 4.5 seconds. In some embodiments, the dose time of each gas is at least 0.5 seconds, at least 1 second, at least 1. 5 seconds, at least 3 seconds, at least 4 seconds, or at least 4.5 seconds.

[0113] In some cases, the ratio of each gas in operation 503 is controlled by tuning the gas flow rate. In some embodiments, the flow rate of the oxygen gas may be between 100 seem and 2000 seem. In some embodiments, the flow rate of the hydrogen is no more than 2000 seem.

[0114] As discussed above, operation 503 may be performed with a process gas containing varying amounts of oxygen. For example, operation 503 may be performed with process gas containing at least 20 % oxygen, at least 30% oxygen, 20 - 30% oxygen, 20 - 50% oxygen, no more than 100% oxygen, or 100% oxygen.

[0115] As discussed previously, operation 503 may be performed at various plasma conditions (e.g., power). For example, operation 503 may be performed power between 150 - 1000 W, at least 150 W, at least 200 W, at least 500 W, at least 750 W, or at least 1000 W. In some embodiments, in operation 503, plasma may be generated using a bias on the pedestal. In some embodiments, the bias in CCP plasma generator is correlated to the power used.

[0116] In some implementations, operation 503 may be repeated one or more times. For example, operation 503 may be repeated at least 5 times, at least 10 times, at least 25 times, at least 30 times, at least 40 times, at least 50 times, or 1 - 100 times. When operation 503 is repeated, each cycle can be performed with the same or different operating conditions. In some implementations, operations 501 and 503 may also be repeated.

[0117] In some embodiments, prior to performing operation 503, native oxides on the surface of the molybdenum-containing layer, on the surface of TiN, and / or on the sidewalls of the feature are optionally removed. In this optional operation, native oxides may be removed by etching. The native oxides may be etched by exposing or soaking the substrates to molybdenum-containing reactants and etching the native oxide. The molybdenum-containing etchant used in this operation may be molybdenum halides, for example, molybdenum chloride such as M0CI5. This optional operation may be performed at varying operating conditions. For example, this operation may be performed at temperatures between 200 °C and 575 °C, or at least 300 °C, or at least 400 °C such as 300 °C or 560 °C. This operation may be performed at pressures between 1.5 and 10 torr, 1.5 and 3 torr, between 0.5 and 3.5 torr, between 1 and 3 torr, between 1 and 3.5 torr, at least 1 torr, or at least 3 torr, such as 1 .5 torr or 3 torr. The details of etching oxides using molybdenum-containing etchant are described further below.

[0118] This optional operation is useful in situations when different operations in process 500 are performed in different chambers and during the transfer between different chambers may expose the substrate to oxygen. The exposure to oxygen during the transfer may result in native oxide formation on the surfaces of the substrate, surfaces of the molybdenum-containing layer, and / or on the sidewalls of the features. For example, the deposition of molybdenum-containing material is performed in one chamber, and operation 503 is performed ex-situ. In such situations, native oxide may be present on the molybdenum surface prior to operation 503. In situations where deposition of the molybdenum-containing material and operation 503 are performed in situ, the optional operation of removing native oxides may not be performed.

[0119] In some implementations, after operation 503, operation 505 may be performed. In operation 505, the molybdenum oxide formed during operation 503 is selectively etched. Selectiveetching may involve a plasma or thermal process using various etch chemistries. For example, operation 505 may involve exposing the molybdenum oxide to one or more chloride-containing or fluorine-containing etch chemistries, or any other suitable etch chemistries may be used to selectively etch the molybdenum oxide.

[0120] In some embodiments, operation 505 involves exposing the molybdenum oxide to a chlorine-containing etchant. Examples of chlorine-containing etchants include molybdenum chlorides (MoClx such as M0CI5), chlorine gas (Ch), boron trichloride (BCh), carbon tetrachloride (CCI4), and combinations thereof. When boron trichloride is used as an etchant, boron oxide may be formed as a byproduct during the etching process.

[0121] In some embodiments, operation 505 involves exposing the molybdenum oxide to a fluorine-containing etchant. Examples of fluorine-containing etchants include hydrogen fluoride (HF), nitrogen trifluoride (NF3), or a metal-containing fluoride such as molybdenum hexafluoride (MoFe), and combinations thereof.

[0122] In some implementations, operation 505 is a vapor-based etch process.

[0123] In some embodiments, operation 505 is performed with or without hydrogen (H2). When H2 is used, H2 plasma may be used to reduce molybdenum oxide to molybdenum. In some cases, incorporating H2 can improve line-to-line or within-the-line uniformity. In some embodiments, operation 505 may involve hydrogen soaking at high temperatures.

[0124] In some embodiments, molybdenum oxide is selectively etched in operation 505. The selectivity of molybdenum oxide relative to molybdenum-containing material may be at least 100: 1, at least 200: 1, at least 300: 1, or at least 500: 1.

[0125] In operation 505, molybdenum oxide on the surface of molybdenum-containing material and the undesired nucleates on the sidewalls of the feature are selectively etched. This selective etching of the molybdenum oxide may allow etching to be stopped at the boundary of molybdenum oxide and underlying molybdenum-containing material, thereby improving surface roughness and line-to-line variation.

[0126] In various implementations, operation 505 may be performed at various temperatures and / or pressures. The temperature and pressure may be changed to tune the selectivity of the etching process. For example, operation 505 may be performed at temperatures between 225 - 400 °C, such as 225 °C, 360 °C, or 400°C. In some embodiments, operation 505 is performed at temperatures above 225 °C, above 350 °C, or above 400°C. In some embodiments, operation 505may be performed at chamber pressures between 0.4 torr and 5 torr, between 0.4 torr and 5 torr, or between 1 torr and 10 torr, such as 3 torr or 10 torr. The details of etching oxides using molybdenum-containing etchant are described further below.

[0127] In some embodiments, operation 505 may reduce the extent of line-to-line variation compared to before performing operation 505. For example, line-to-line variation prior to performing operation 503 may be about 1.5 nm, 1.7 nm, or 2.0 nm, or between 1.5 - 2.0 nm whereas line-to-line variation after performing operation 503 may be about 1 nm, about 1.2 nm, about 1.5 nm, about 1.6 nm, between 1 nm and 2 nm.

[0128] In addition to improvements in line-to-line variation, operation 505 may improve variation in molybdenum thickness compared to before performing operation 505. For example, the variation in molybdenum thickness prior to performing operation 505 may be 3.4 nm, 3.5 nm, 4 nm, 4.2 nm, or between 3.4 - 4.5 nm, while the variation in molybdenum thickness after operation 505 may be about 2.3 nm, about 2.4 nm, about2.7 nm, about 2.8 nm, about 3.3 nm, about 3.8 nm, or between 2 - 4 nm. In some embodiments, the variation in molybdenum thickness prior to performing operation 505 is about 2.1 whereas this variation after performing operation 505 is 1.3 - 1.5 nm.

[0129] In some embodiments, operation 505 may be repeated one or more times. For example, operation 505 may be repeated 50 - 200 times, or 50 - 350 times, such as 80 times or 300 times. In some embodiments, operation 505 is repeated at least 50 times, at least 100 times, at least 200 times, or at least 300 times. When operation 505 is repeated, each cycle can be performed with the same or different operating conditions.

[0130] In some embodiments, in addition to or as an alternative to operation 505, molybdenum oxide may be converted into molybdenum by exposing the molybdenum oxides on the surfaces and the sidewalls of the feature to a reducing agent. In some embodiments, this may involve a H plasma treatment or any other suitable reduction methods with an appropriate reducing agent. For example, molybdenum oxides can be exposed to H2 to reduce molybdenum oxide and convert to molybdenum. In some embodiments, converting molybdenum oxide to molybdenum may involve soaking the featured substrate in hydrogen gas. In some embodiments, undesired byproducts such as residual chlorine or fluorine is removed during the process.

[0131] In some implementations, operation 505 may deposit additional molybdenum-containing material over the underlying molybdenum to fill the plurality of features. In some embodiments,after operation 505, additional molybdenum-containing material is deposited to fill the plurality of features.

[0132] In some implementations, operations 503 and 505 may also be repeated in a cyclic fashion. For example, the sequence of operations (e.g., operation 503 followed by operation 505) may be repeated twice, or 50 - 300 times.

[0133] In some implementations, operations 501, 503, and 505 may be repeated in a cyclic fashion. For example, a featured substrate having a molybdenum-containing material deposited thereon may be provided, and a portion of the molybdenum-containing layer is oxidized to form a molybdenum oxide. The molybdenum oxide may then be selectively etched. Following the selectively etch process, additional molybdenum-containing material may be deposited, and the aforementioned operations may be repeated.

[0134] In some embodiments, process 500 is practiced after molybdenum feature fill as a posttreatment process. In some cases, process 500 is incorporated into the molybdenum deposition or the feature fill process. In some embodiments, process 500 is practiced as a pre-treatment prior to molybdenum feature fill on a titanium nitride plug. The details of an example of pre-treatment process are described with reference to Figure 7.

[0135] Each operation in the process 500 may be performed in the same or different process chamber.

[0136] In some implementations, the process may be performed with nitridation (or any other suitable surface modification) instead of oxidation. This process is illustrated in Figure 6. As depicted in Figure 6, process 600 begins with operation 601, in which a substrate having a layer of molybdenum-containing material deposited therein is provided. In operation 603, at least a portion of the molybdenum-containing material is nitridated, thereby forming a layer of molybdenum nitride. In operation 605, the molybdenum nitride is selectively etched. Process 600 is largely similar to process 500 with the exception of nitridation in place of oxidation, forming molybdenum nitride, and selectively etching molybdenum nitride. Process 600 can be practiced with various specific details (e.g., operating conditions, etch conditions, etch selectivity, etch thickness, line-to-line variation, etc.) in process 500 described above.

[0137] For example, operation 601 may be practiced with details according to operation 501 .

[0138] In operation 603, a portion of the molybdenum-containing material is nitridated thereby forming a layer of molybdenum nitride. Similar to operation 503, operation 603 may lead tosmoothening of the surface due to volume expansion upon nitridation of the molybdenum- containing material. Operation 603 can reduce the molybdenum faceting and line-to-line variation and improve the selectivity of the molybdenum deposition by removing undesired nucleates on the feature and / or feature sidewalls.

[0139] In some embodiments, the substrate is exposed to a nitrogen-containing plasma during operation 603. In some embodiments, the nitrogen-containing plasma is N2 plasma.

[0140] In some embodiments, operation 603 may be performed by exposing the substrate to a thermal treatment process such as NH3 thermal soak process.

[0141] Similar to operation 503, operation 603 may be performed at various operating conditions which can be tuned to influence the thickness of the molybdenum nitride formed during operation 603. Examples of the tunable operating conditions include, but are not limited to, gas flow rate, the ratio of nitrogen (e.g., % volume), temperature, pressure, dose time of the gases, and plasma generation conditions such as power, and bias.

[0142] Similar to operation 503, operation 603 may be repeated one or more times.

[0143] Referring to operation 605, in some implementations, operation 605 is performed after operation 603. In operation 603, molybdenum nitride formed during operation 603 is selectively etched. Similar to operation 503, selective etching may be a plasma or thermal soak process using various etch chemistries. Operation 605 may be performed with any suitable etch chemistries with desired etch selectivity towards molybdenum nitride over molybdenum-containing material.

[0144] Similar to operation 505, operation 605 involves exposing the molybdenum nitride to a chlorine-containing etchant. Chlorine-containing etchant may be a molybdenum chloride (e.g., MoCl x such as M0CI5), chlorine gas (CI2), boron trichloride (BCI3), carbon tetrachloride (CCI4), or combinations thereof.

[0145] In some embodiments, operation 605 involves exposing the molybdenum nitride to a fluorine-containing etchant. Fluorine-containing etchant may be a hydrogen fluoride (HF), nitrogen trifluoride (NF3), or a metal-containing fluoride such as tungsten hexafluoride (WFe), or combinations thereof.

[0146] In some embodiments, operation 605 is performed with or without hydrogen (H2). When H2 is used, H2 plasma may be used to reduce molybdenum nitride to molybdenum. In some cases,incorporating H2 can improve line-to-line or within-the-line uniformity. In some embodiments, operation 605 may involve hydrogen soaking at high temperatures.

[0147] In some embodiments, molybdenum nitride is selectively etched in operation 605. The selectivity of molybdenum nitride relative to molybdenum-containing material may be at least 100: 1, at least 200: 1, at least 300:1, or at least 500:1.

[0148] In operation 605, molybdenum nitride on the surface of molybdenum-containing material and the undesired nucleates on the sidewalls of the feature are selectively etched. This selective etching of the molybdenum nitride may improve surface roughness and line-to-line variation.

[0149] Similar to operation 505, operation 605 may be performed at various temperatures and / or pressures as outlined in operation 505.

[0150] Operation 605 may improve line-to-line variation, variation in molybdenum thickness by a similar extent to operation 505.

[0151] As discussed in operation 505, operation 605 may be repeated one or more times, and each cycle can be performed with same or different operating conditions. In some implementations, operations 603 and 605 may also be repeated in a cyclic fashion. In some embodiments, process 600 is practiced as a pre-treatment or as a post-treatment in molybdenum- feature fill.

[0152] In some embodiments, process 600 is practiced as a pre-treatment prior to molybdenum feature fill to treat a titanium nitride plug. Further description of a pre-treatment process is below with reference to Figure 7.

[0153] Figure 7 illustrates example operations for pre-treatment process 700. Process 700 begins with operation 701, in which a substrate having a layer of titanium nitride deposited therein is provided. In operation 703, a portion of titanium nitride is oxidized, thereby forming titanium oxynitride. In operation 705, the titanium oxynitride is selectively etched. In operation 707, molybdenum-containing material may be deposited in the feature. Process 700 is similar to process 500 except for the material that is being oxidized and the identity of the oxidized material. For example, in process 500, operation 503 oxidizes molybdenum-containing material and forms molybdenum oxides whereas in operation 703, titanium nitride is oxidized and forms titanium oxynitride. Process 700 may be practiced with various specific details (e.g., operating conditions, etch conditions, etch selectivity, etch thickness, line-to-line variation, etc.) corresponding to process 500.

[0154] In operation 701 , the substrate may be a featured substrate. For example, the substrate has a plurality of features spaced apart; each feature may have a feature opening, and the titanium nitride (TiN) is deposited on the bottom portion of the feature therein. The TiN may act as a plug, in which the molybdenum-containing material may be preferentially deposited. One challenge associated with TiN plug is that its surface conditions can vary substantially (e.g., roughness of the surface, line-to-line variation, etc.). The variation on the TiN plug can lead to challenges in subsequent steps (e.g., molybdenum feature fill). In addition, the presence of surface contaminants (e.g., fluorine and / or chlorine) or residual TiN on the sidewalls of the feature can lead to selectivity loss. When used, process 700 can mitigate the issue related to TiN plug and improve the quality of subsequent molybdenum fill.

[0155] In operation 703, a portion of titanium nitride is oxidized, thereby forming a layer of titanium oxynitride (TiOxNy). Examples of titanium oxynitride include but are not limited to TiNO.

[0156] Similar to operation 503, in operation 703, titanium nitride is oxidized by exposing the substrate to an oxy gen-containing plasma. In some embodiments, oxygen-containing plasma is generated from a gas containing oxygen (O2) or any other suitable oxygen-containing gases. In some implementations, oxygen-containing plasma may be generated from a mixture of gases. For example, oxygen-containing plasma may be generated from a mixture of gases containing one or more inert gases such as hydrogen (H2), argon (Ar), helium, and combinations thereof. In some embodiments, operation 703 involves exposing the featured substrate to ozone-soak gas. In some embodiments, operation 703 involves exposing the featured substrate to water-soaked gas.

[0157] In some embodiments, operation 703 involves exposing the titanium nitride to a hydrogencontaining plasma, which can be H2 plasma.

[0158] Similar to operation 503, operation 603 may be performed at various operating conditions which can be tuned to influence the thickness of the molybdenum nitride formed during operation 603. Examples of the tunable operating conditions include, but are not limited to, gas flow rate, the ratio of oxygen (e.g., % volume), temperature, pressure, dose time of the gases, and plasma generation conditions such as power, and bias.

[0159] Similar to operation 503, operation 703 may be repeated one or more times.

[0160] In some embodiments, the featured substrate with a TiN plug may have a TiN plug that contains impurities (e.g., oxygen impurities), and TiN may already have a level of oxidation, and titanium oxynitride may be present. In some of these cases, operation 703 may be omitted, and the titanium oxynitride may be removed in operation 705.

[0161] Referring to operation 705, in some implementations, operation 705 is performed after operation 703. In operation 703, titanium oxynitride formed during operation 703 is selectively etched. Similar to operation 503, selective etching may be a plasma or thermal soak process using various etch chemistries. Operation 705 may be performed with any suitable etch chemistries with desired etch selectivity towards titanium oxynitride over TiN.

[0162] Similar to operation 505, operation 705 involves exposing the titanium oxynitride to a chlorine-containing etchant. Chlorine-containing etchants may be chlorine gas (Ch), boron trichloride (BCh), carbon tetrachloride (CCI4), or combinations thereof.

[0163] In some embodiments, operation 705 involves exposing the titanium oxynitride to a fluorine-containing etchant. Fluorine-containing etchant may be a hydrogen fluoride (HF), nitrogen trifluoride (NF3), or a metal-containing fluoride such as tungsten hexafluoride (WFe), or combinations thereof.

[0164] In some embodiments, titanium oxynitride is selectively etched in operation 705. The selectivity of titanium oxynitride relative to TiN may be at least 100: 1, at least 200:1, at least 300:1, or at least 500:1.

[0165] Similar to operation 505, operation 705 may be performed at various temperatures and / or pressures as outlined in operation 705.

[0166] Operation 705 may improve line-to-line variation and variation in TiN thickness to a similar extent to operation 505.

[0167] As discussed in operation 505, operation 705 may be repeated one or more times, and each cycle can be performed with the same or different operating conditions. In some implementations, operations 703 and 705 may also be repeated in a cyclic fashion.

[0168] After operation 705, molybdenum may be deposited in the features. Due to the improved properties and selectivity of the TiN, the resultant molybdenum material may have improved properties such as surface roughness, line-to-line variation... etc.Molybdenum deposition

[0169] In the methods described herein, molybdenum deposition may be performed to deposit molybdenum-containing material in the feature, such as those depicted in Figures 1A, IB, 2A - 2L, 3 and 4. Deposition of molybdenum as described herein involves reacting a Mo-containing precursor, also referred to as a molybdenum precursor. In some embodiments, a molybdenumhalide compound as described above is used. In methods including surface treatment using a molybdenum halide compound, the same or different compound may be used for deposition.

[0170] In some embodiments, a Mo precursor is a molybdenum chloride (MoClx) compound also referred to as a molybdenum chloride precursor or MoClxprecursor. In some embodiments, Mo deposition may use a molybdenum oxyhalide precursor. Molybdenum chloride precursors are given by the formula MoClx, where x is 2, 3, 4, 5, or 6, and include molybdenum dichloride (MoCh), molybdenum trichloride (M0CI3), molybdenum tetrachloride (M0CI4), molybdenum pentachloride (M0CI5), and molybdenum hexachloride (MoCE). In some embodiments, M0CI5 or MoCle are used. While the description chiefly refers to MoClxprecursors, in other embodiments, other molybdenum halide precursors may be used. Molybdenum halide precursors are given by the formula MoXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)) and z is 2, 3, 4, 5, or 6. Examples of MoXzprecursors include molybdenum fluoride (MoFe). In some embodiments, a non-fluorine-containing MoXzprecursor is used to prevent fluorine etch or incorporation. In some embodiments, a non-bromine-containing and / or a non-iodine-containing MoXzprecursor is used to prevent etch or bromine or iodine incorporation.

[0171] In some embodiments, the feature may be filled using a molybdenum oxyhalide precursor. Molybdenum oxyhalide precursors are given by the formula MoOyXz, 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 MoOyXzforms a stable compound. Examples of molybdenum oxyhalides include molybdenum dichloride dioxide (MOO2Q2), molybdenum tetrachloride oxide (MoOCU), molybdenum tetrafluoride oxide (M00F4), molybdenum dibromide dioxide (MoCbB ), and the molybdenum iodides MOO2I, and MO4O11I. 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 that includes molybdenum, oxygen, a halide and one or more other elements. In some embodiments, molybdenum oxyhalide or molybdenum-containing oxyhalides may include multiple different halogens (e.g., F and Cl and / or I and / or Br, etc.). A feature may be filled with molybdenum using a MoClxprecursor, MoOyXzprecursor, or a combination thereof.

[0172] For deposition of molybdenum into the feature, the molybdenum precursor may be reacted with a co-reactant. Examples of co-reactants include hydrogen (H2), silane (SiFU), diborane (B2H6), germane (GeFU), ammonia (NH3), and hydrazine (N2H4).

[0173] In some embodiments, deposition of molybdenum may use a plasma-based process. Gas may be fed into a remote or in-situ plasma generator to generate plasma species. Examples of gasthat may be used to generate plasma may be a hydrogen-containing gas, such as H2, nitrogencontaining gas, such as nitrogen (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.

[0174] A feature may be filled with molybdenum by atomic layer deposition (ALD) or chemical vapor deposition (CVD). Thermal ALD or plasma enhanced ALD (PE ALD) may be used. Similarly, thermal CVD or plasma enhanced CVD (PECVD) may be used.

[0175] ALD is a surface-mediated deposition technique in which doses of a precursor and a reactant are sequentially introduced into a deposition chamber. One or more cycles of sequential doses of a molybdenum precursor and reactant may be used to deposit Mo. For example, in the deposition of an initial molybdenum layer, M0CI5 may be used as a precursor and H2 as a reducing agent. Doses of M0CI5 and H2 are sequentially introduced into the deposition chamber with a purge gas, such as argon, flowed between. For ALD, the temperature of the substrate and the pressure of the chamber may be controlled. For example, the substrate may be heated between 200°C and 800°C, e.g., between 250°C and 550°C or between 35O°C and 450°C. In some embodiments, the chamber may be pressurized between 10 Torr and 200 Torr, e.g., between 50 Torr and 90 Torr. In some embodiments, the temperature and / or pressure may be used to control the rate of reactions. In some embodiments, the temperature and / or pressure may be used to control selectivity.

[0176] In some embodiments, molybdenum fill may involve CVD. In a CVD process, the molybdenum precursor and reactant are in vapor phase together in the deposition chamber. Generally speaking, a CVD process fills a feature faster than an ALD process. In one example, the precursor may be a molybdenum oxychloride, such as MOO2CI2, and is flowed into the chamber with a reactant, such as H2. In this example, the wafer is simultaneously exposed to the precursor and reactant, which react and fill features with Mo.

[0177] In still some other embodiments, a feature may be filled using a pulsed CVD process. The pulsed CVD process continuously flows a reactant into a chamber while pulses of a precursor flow into the chamber. For example, H2 gas may be flowed into the chamber and is continuously flowing into the chamber while the molybdenum-containing precursor is intermittently flowing into the chamber. The temperature of the substrate and pressure in the chamber may be controlled during a CVD operation.

[0178] Molybdenum may be selectively deposited into a feature using the methods described herein. Selective deposition refers to preferential deposition on a first material with respect to asecond material. Molybdenum deposition and growth may be easier on a metal material relative to molybdenum deposition and growth on a dielectric material. For example, a feature may have a sidewall surface of SiCh and a TiN plug in the bottom portion of the feature. In selective deposition, molybdenum is deposited into the feature and may grow on the TiN plug but not grow (or grow to a lesser extent) on the SiCh sidewall surfaces.

[0179] Process conditions such as the precursor gas, the reducing agent, process temperature, process pressure, and exposure time may affect the selectivity of the molybdenum film being deposited. Different precursor gases may have different process windows in which molybdenum film may be selectively deposited. Generally speaking, M0CI5 gas has a large process window, i.e., large temperature and pressure range, where the precursor gas retains its selectivity. For example, M0CI5 may be selectively deposited on a metal material with respect to a dielectric material where the process temperature is 200°C to 800°C, e.g., 250°C to 550°C, or 300°C to 500°C. Generally speaking, higher process temperatures and higher process pressures reduce the selectivity of the deposited gas. For example, at higher temperatures, a precursor gas such as M0CI5 may lose its selectivity and deposit molybdenum film on both a metal surface and a dielectric surface within a feature.

[0180] M0CI5 may be reacted with different reactant to deposit a molybdenum film. Described below are examples of deposition of molybdenum film within a feature using a M0CI5 precursor and different process controls. In a first example, the M0CI5 precursor is reacted with a hydrogen (H2) reactant using the deposition methods described above. In the description herein, the metal precursors are reacted with hydrogen (H2) as a co-reactant (also referred to as a hydrogen reactant or H2 reactant). However, other reactants may be used instead of hydrogen including other hydrogen-containing reactants such SiH4, B2H6, NH3, as appropriate. While reactants such as B2H6 and / or SiH4 are stronger reducing agents, they can also result in higher resistivity. Thus, in some embodiments, using H2 as described herein is advantageous. Process temperatures for selective deposition of the molybdenum film may be between 200°C to 800°C, e.g., 250°C to 550°C, or 300°C to 500°C. At these temperatures, the molybdenum film is selectively deposited on conductive metal or metal compound surfaces, such as a TiN surface, in a feature relative to dielectric surfaces. The molybdenum film grows from the locations where the conductive surfaces are located in a feature. If the conductive surface is a TiN plug at the bottom of the feature, the molybdenum film may be deposited and grown from the bottom of the feature. In a second example, the molybdenum film may be deposited using the M0CI5 precursor and the H2 reactant, but at higher temperatures, i.e., above 800°C. This process window may have the molybdenum film deposited on both the dielectric and conductive surfaces within the feature. The depositionof the molybdenum film on the dielectric surface may be used to create a barrierless molybdenum layer in the feature.

[0181] In some embodiments, selective deposition is performed using a molybdenum oxyhalide precursor. As described above, the surface treatments described above significantly improve selectivity of Mo deposition from MOO2Q2. As indicated above, examples of MoOyXzprecursors include MOO2CI2, MoOCh, M00F4, MoChBn, MoOrl, and MO4O11I. The feature may be filled using ALD, plasma enhanced ALD, chemical vapor deposition (CVD), or plasma enhanced CVD. For ALD or CVD, H2 may be the reducing agent. Molybdenum deposits more quickly using a molybdenum oxyhalide precursor than the MoClxprecursor used in the surface treatment. For example, a MoOyXzprecursor may deposit molybdenum at a deposition rate at least twice as fast as a MoClxprecursor for a non-plasma process. Plasma enhanced processes may be used to fill features at lower temperatures and / or increase deposition rates.

[0182] In some embodiments, filling a feature can involve depositing a nucleation layer. A nucleation layer is a thin layer that supports bulk deposition. It may be conformal to the feature. In many embodiments, a nucleation layer is deposited by an ALD process. In some embodiments, a Mo 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., SiFL) as a co-reactant. For example, one or more S / Mo cycles or Mo / S cycles may be used to deposit a Mo nucleation layer. In another example, one or more B / Mo cycles or Mo / B cycles may be used to deposit a Mo nucleation layer on which a bulk Mo layer is deposited. B refers to a pulse of diborane or other boron-containing reducing agent and S to a pulse of silane or other silicon-containing reducing agent, such that S / Mo refers to a pulse of silane followed by a pulse of a Mo-containing precursor. B / Mo and S / Mo cycles (or Mo / B and / or Mo / S) may both be used to deposit a Mo nucleation layer, e.g., x(B / Mo) + y(S / Mo), with x and y being integers. Examples of boron-containing reactants include diborane (B2H6), alkyl boranes, alkyl boron, aminoboranes (CHr)2NB(CH2)2, carboranes such as C2BnHn+2, and other boranes. Examples of boranes include BnHn+4, BnHn46, BnHn+8, BnHm, where n is an integer from 1 to 10, and m is a different integer than m. Examples of silicon-containing reducing agents including silane (SiFL) and other silanes such as disilane (Si2He).

[0183] In some embodiments, deposition of a Mo nucleation layer may involve using a non- oxygen-containing precursor, e.g., molybdenum hexafluoride (MoFe) or molybdenum pentachloride (M0CI5). Oxygen in oxy gen-containing precursors may react with a silicon- or boron-containing reducing agent to form MoSixOyor MoBxOy, which are impure, high resistivity films. In some embodiments, oxygen-containing precursors may be used for nucleation layerdeposition with oxygen incorporation minimized. Oxygen incorporation can be minimized by high reducing agent flows (e.g., greater than 100: 1 volumetric flow rate of reducing agent to oxy gen-containing Mo precursor).

[0184] In some embodiments, EL may be used as a reducing gas for Mo nucleation layer deposition instead of a boron-con taining or silicon-containing reducing gas. Example thicknesses for deposition of a Mo nucleation layer range from 5 A to 30 A. Films at the lower end of this range may not be continuous: however, as long as they can help initiate continuous bulk Mo grow th, the thickness may be sufficient.

[0185] In some embodiments, the reducing agent pulses during deposition of a nucleation or bulk Mo layer may be done at lower substrate temperatures than the Mo precursor pulses. For example, or B2H6 or a SiEL (or other boron- or silicon-containing reducing agent) pulse may be performed at a temperature below 300°C, with the Mo pulse at temperatures greater than 300°C.

[0186] In some embodiments, the reducing agent is NH3 or other nitrogen-containing reducing agents such as hydrazine (N2H4). NH3 chemisorption on dielectrics is more favorable than that of H2. In some embodiments, the reducing agent and precursor are selected such that they react without reducing agent dissociation. NH3 reacts with metal oxychlorides and metal chlorides without dissociation. This is in contrast to, for example, ALD from metal oxychlorides that use H2 as a reducing agent; H2 dissociates on the surface to form adsorbed atomic hydrogen, which results in very low concentrations of reactive species and low surface coverage during initial nucleation of metal on the dielectric surface. By using NH3 and metal oxychloride or metal chloride precursors, nucleation delay is reduced or eliminated at deposition temperatures up to hundreds of degrees lower than used by H2 reduction of the same metal precursors.

[0187] In some embodiments, the reducing agent may be a boron-containing or silicon-containing reducing agent such as B2H6 or SiEfl. These reducing agents may be used with metal chloride precursors, with metal oxychlorides; however, the B2H6 and SiFU may react with water formed as a byproduct during the ALD process and form solid B2O3 and SiC . These are insulating and can remain in the film, increasing resistivity. Use of NH3 also has improved adhesion over B2H6 and SiEfl ALD processes on certain surfaces including AI2O3. The resulting nucleation layer is generally 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, particularly if the deposition is performed at low temperatures. In some embodiments, there may be no more than a trace amount 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) facilitatethe growth of an amorphous microstructure. In some embodiments, the nucleation layer as deposited is an amorphous molybdenum oxynitride layer or an amorphous molybdenum nitride layer. The amorphous character templates large grain growth in the subsequently deposited conductor. The surface energy of nitride or oxynitride relative to an oxide surface is much more favorable than that of a metal on an oxide surface, facilitating formation of a continuous and smooth fdm on the dielectric. This allows formation of thin, continuous layers. Example thicknesses of the nucleation layer range from 5-30A as deposited. Depending on the temperature, this may be about 5-50 ALD cycles, for example.Etch

[0188] Etch operations may be used in the methods for filling features with Mo films. Etch operations remove materials such as metals, oxides, and nitrides from the feature. For example, an etch process may partially or completely remove a liner layer from a feature. In another example, the etch process may be used to reduce the thickness of a liner layer. The etch operation, in some embodiments, may involve soaking the feature soaked in a Mo halide. In some embodiments, an etch operation involves soaking the feature with a MoClxsuch as M0CI5. In some embodiments, the soak may be done continuously with the Mo halide gas. In some embodiments, the soak may be pulsed, cycling the Mo halide with a purge gas, such as argon (Ar).

[0189] A MoClx precursor may be used for both deposition and etch operations. For example, in certain process windows, a M0CI5 precursor may concurrently grow a Mo film and etch away a portion of the film in the feature. The process is considered a net etch operation if the rate of material removed is greater than the material deposited by the precursor. The speed at which the precursor deposits material and etches material may be controlled by a variety of process conditions, including the type of reactant used and the process temperature. Generally speaking, the lower the temperature, the higher the ratio of etching away material is relative to the deposition of material. At higher temperatures, the same precursor and reactant may be used as a net deposition operation, i.e., the amount of material deposited is greater than the material removed. For example, M0CI5 precursor and H2 reactant may be used in an etch operation when the process temperature is below 400 °C. The same precursor of M0CI5 and H2 reactant may be used in a deposition operation when the process temperature is above 550 °C.

[0190] In some embodiments, the MoClx precursor at high temperatures, e.g., above 550 °C, may continue to etch material at a faster rate than depositing material. For example, M0CI5 may be used to etch a feature by a soak without a reactant. In this example, the temperature may be as high as700 °C, and will continue to etch away material from the feature. In operations where the feature is soaked in a M0CI5 without a reactant, the increased temperature may increase the rate at which material is etched from the feature.

[0191] A feature may have surface oxide or contaminants on it. For example, the surface of an underlying TiN, WN, or W layer may be oxidized. If left, the oxidized surface can result in higher resistivity. Clean operations are used to remove such oxides and contaminants. In some embodiments, the clean operation may have the feature soaked in a Mo precursor gas, typically a Mo halide. Similar to the etch operations described above, the precursor gas may be a MoClxprecursor. In some embodiments, the soak may be done continuously. In some embodiments, the soak may be pulsed, cycling MoClxand a purge gas, such as argon (Ar). The precursor may be a non-oxygen Cl-containing Mo compound able to remove oxidation from the feature’s surfaces. Examples of MoClxcompounds are given ae. A Cl-containing precursor may be used where traditional cleaning with thermal or plasma H2 does not work, such as where the oxidized surface is stable on the surface material. A Cl-containing precursor is less likely to over-etch a feature’s liner layer or attack a feature’s surfaces than an F-containing compound.Apparatus

[0192] The methods described herein can be carried out in a variety of apparatuses. A suitable apparatus includes one or more process chambers (i.e., multi-station tool), a substrate holder in the process chamber configured to hold the substrate in place during the process, and a plasma generating mechanism configured for generating plasma in a process gas. Examples of suitable apparatuses include inductively coupled plasma (ICP) reactors, capacitively coupled plasma (CCP) reactors, or remote plasma reactors, which, in certain embodiments, may also be suitable for a molybdenum deposition process (e.g., ALD operations) and / or etching process. In some implementations, each or some operation in the method described herein can be carried out in different apparatuses. For example, deposition and plasma treatment may be carried out in a separate apparatus, and oxidation / nitridation and etch operations may be carried out in a different apparatus. Further descriptions of the apparatuses that can be used to practice the methods described herein are detailed below.

[0193] Figure 8 depicts a schematic illustration of an embodiment of an ALD process station 800 having a process chamber 802 for maintaining a low-pressure environment. In some embodiments, a plurality of ALD process stations may be included in a common low-pressure process tool environment. For example, Figures 9A and 9B depict embodiments of a multi-station processingtool 900. In some embodiments, one or more hardware parameters of ALD process station 800, including those discussed in detail below, may be adjusted programmatically by one or more computer controllers 950. In some other embodiments, a process chamber may be a single-station chamber.

[0194] ALD process station 800 fluidly communicates with reactant delivery system 801a for delivering process gases to a distribution showerhead 806. Reactant delivery system 801a includes a mixing vessel 804, for blending and / or conditioning process gases, such as a Mo precursorcontaining gas, a hydrogen-containing gas, an argon or other carrier gas, or other reactantcontaining gas, for delivery to showerhead 806. One or more mixing vessel inlet valves 820 may control the introduction of process gases to mixing vessel 804. In various embodiments, deposition of an initial Mo layer is performed in process station 800, and in some embodiments, other operations such as inOsitu clean or Mo gap fill may be performed in the same or another station of the multi-station process tool 900 as further described below with respect to Figure 9A.

[0195] As an example, the embodiment of Figure 8 includes a vaporization point 803 for vaporizing liquid reactant to be supplied to the mixing vessel 804. In some embodiments, vaporization point 803 may be a heated vaporizer. In some embodiments, a liquid precursor or liquid reactant may be vaporized at a liquid injector (not shown). For example, a liquid injector may inject pulses of a liquid reactant into a carrier gas stream upstream of the mixing vessel 804. In one embodiment, a liquid injector may vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another example, a liquid injector may atomize the liquid into dispersed microdroplets that are subsequently vaporized in a heated delivery pipe. Smaller droplets may vaporize faster than larger droplets, reducing the delay between liquid injection and complete vaporization. Faster vaporization may reduce the length of piping downstream from vaporization point 803. In one scenario, a liquid injector may be mounted directly to mixing vessel 804. In another scenario, a liquid injector may be mounted directly to showerhead 806.

[0196] In some embodiments, a liquid flow controller (LFC) upstream of vaporization point 803 may be provided for controlling a mass flow of liquid for vaporization and delivery to process chamber 802. For example, the LFC may include a thermal mass flow meter (MFM) located downstream of the LFC. A plunger valve of the LFC may then be adjusted responsive to feedback control signals provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, it may take one second or more to stabilize liquid flow using feedback control. This may extend the time for dosing a liquid reactant. Thus, in some embodiments, the LFC may be dynamically switched between a feedback control mode and adirect control mode. In some embodiments, this may be performed by disabling a sense tube of the LFC and the PID controller.

[0197] Showerhead 806 distributes process gases toward substrate 812. In the embodiment shown in Figure 8, the substrate 812 is located beneath showerhead 806 and is shown resting on a pedestal 808. Showerhead 806 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to the substrate.

[0198] In some embodiments, pedestal 808 may be raised or lowered to expose substrate 812 to a volume between the substrate 812 and the showerhead 806. In some embodiments, pedestal 808 may be temperature controlled via heater 810. Pedestal 808 may be set to any suitable temperature, such as between about 250°C and about 800°C during operations for performing various disclosed embodiments. It will be appreciated that, in some embodiments, pedestal height may be adjusted programmatically by a suitable computer controller. At the conclusion of a process phase, pedestal 808 may be lowered during another substrate transfer phase to allow removal of substrate 812 from pedestal 808.

[0199] In some embodiments, a position of showerhead 806 may be adjusted relative to pedestal 808 to vary a volume between the substrate 812 and the showerhead 806. Further, it will be appreciated that a vertical position of pedestal 808 and / or showerhead 806 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 808 may include a rotational axis for rotating an orientation of substrate 812. It will be appreciated that, in some embodiments, one or more of these example adjustments may be performed programmatically by one or more suitable computer controllers 850. The computer controller 850 may include any of the features described below with respect to controller 850 of Figure 8.

[0200] In some embodiments where plasma may be used as discussed above, showerhead 806 and pedestal 808 electrically communicate with a radio frequency (RF) power supply 814 and matching network 816 for powering a plasma. In some embodiments, the plasma energy may be controlled by controlling one or more of a process station pressure, a gas concentration, an RF source power, an RF source frequency, and a plasma power pulse timing. For example, RF power supply 814 and matching network 816 may be operated at any suitable power to form a plasma having a desired composition of radical species. Likewise, RF power supply 814 may provide RF power of any suitable frequency. In some embodiments, RF power supply 814 may be configured to control high- and low-frequency RF power sources independently of one another. Example low-frequency RF frequencies may include, but are not limited to, frequencies between 0 kHz and 900 kHz. Example high-frequency RF frequencies may include, but are not limited to, frequenciesbetween 1.8 MHz and 2.45 GHz, or greater than about 13.56 MHz, or greater than 27 MHz, or greater than 80 MHz, or greater than 60 MHz. It will be appreciated that any suitable parameters may be modulated discretely or continuously to provide plasma energy for the surface reactions.

[0201] In some embodiments, the plasma may be monitored in-situ by one or more plasma monitors. In one scenario, plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, plasma density and / or process gas concentration may be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters may be programmatically adjusted based on measurements from such in-situ plasma monitors. For example, an OES sensor may be used in a feedback loop for providing programmatic control of plasma power. It will be appreciated that, in some embodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0202] In some embodiments, instructions for a controller 850 may be provided via input / output control (IOC) sequencing instructions. In one example, the instructions for setting conditions for a process phase may be included in a corresponding recipe phase of a process recipe. In some cases, process recipe phases may be sequentially arranged, so that all instructions for a process phase are executed concurrently with that process phase. In some embodiments, instructions for setting one or more reactor parameters may be included in a recipe phase. For example, a first recipe phase may include instructions for setting a flow rate of an inert and / or a reactant gas (e.g., a Mo precursor), instructions for setting a flow rate of a carrier gas (such as argon), and time delay instructions for the first recipe phase. A second, subsequent recipe phase may include instructions for modulating or stopping a flow rate of an inert and / or a reactant gas, and instructions for modulating a flow rate of a carrier or purge gas and time delay instructions for the second recipe phase. A third recipe phase may include instructions for modulating a flow rate of a second reactant gas such as H2, instructions for modulating the flow rate of a carrier or purge gas, instructions for igniting a plasma, and time delay instructions for the third recipe phase. A fourth, subsequent recipe phase may include instructions for modulating or stopping a flow rate of an inert and / or a reactant gas, and instructions for modulating a flow rate of a carrier or purge gas and time delay instructions for the fourth recipe phase. It will be appreciated that these recipe phases may be further subdivided and / or iterated in any suitable way within the scope of the present disclosure.

[0203] Further, in some embodiments, pressure control for process station 800 may be provided by butterfly valve 818. As shown in the embodiment of Figure 8, butterfly valve 818 throttles avacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of process station 800 may also be adjusted by varying a flow rate of one or more gases introduced to the process station 800.

[0204] Figure 9A and Figure 9B show examples of processing systems. Figure 9A shows an example of a processing system including multiple chambers. The system 900 includes a transfer module 903. The transfer module 903 provides a clean, vacuum environment to minimize risk of contamination of substrates being processed as they are moved between various modules. Mounted on the transfer module 903 is a multi-station chamber 909 capable of performing in-situ clean and / or ALD processes described above. Surface treatment and / or initial Mo layer deposition may be performed in the same or different station or chamber as the subsequent Mo gap fill.

[0205] Chamber 909 may include multiple stations 911, 913, 915, and 917 that may sequentially perform operations in accordance with disclosed embodiments. For example, chamber 909 may be configured such that station 911 performs pretreatment process or liner deposition process, station 913 performs ALD deposition of molybdenum-containing material in a featured substrate using a molybdenum halide precursor and a reducing agent (e.g., Hi). Station 915 may be configured to oxidize or nitridated a portion of the molybdenum-containing material to form a molybdenum oxide or molybdenum nitride. Stations 917 may be configured to selectively etch the molybdenum oxide or molybdenum nitride with respect to molybdenum-containing material, exposing the underlying molybdenum-containing material. In another example, chamber 909 may be configured to do parallel processing of substrates, with each station performing multiple processes sequentially.

[0206] Two or more stations may be included in a multi-station chamber, e.g., 2-6, with the operations appropriately distributed. For example, a four-station chamber may be configured to perform ALD of an initial Mo layer in a first station, plasma treatment in a second chamber, etching in a third chamber, followed by ALD of bulk Mo in a fourth station. Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0207] Also mounted on the transfer module 903 may be one or more single or multi-station modules 907. In some embodiments, a preclean as described above may be performed in a module 907, after which the substrate is transferred under vacuum to another module (e.g., another module 907 or chamber 909) for ALD. In another example, a module for selective treatment of a film may be mounted on the transfer module.

[0208] The system 900 also includes one or more wafer source modules 901, where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 919 may first remove wafers from the source modules 901 to loadlocks 921. A wafer transfer device (generally a robot arm unit) in the transfer module 903 moves the wafers from loadlocks 921 to and among the modules mounted on the transfer module 903.

[0209] In some embodiments, ALD of Mo is performed in a first chamber, which may be part of a system like system 900, with CVD or PVD of W or Mo or other conductive material deposited as an overburden layer performed in another chamber, which may not be coupled to a common transfer module, but part of another system.

[0210] Figure 9B is an embodiment of a system 900. The system 900 in Figure 9B has wafer source modules 901, a transfer module 903, atmospheric transfer chamber 919, and loadlocks 921, as described above with reference to Figure 9A. The system in Figure 9B has three single station modules 957a-975c. The system 900 may be configured to sequentially perform operations in accordance with disclosed embodiments. For example, the single station modules 957a-957c may be configured so that a first module 957a performs the initial deposition of molybdenum- containing material, a second module 957b performs surface treatments and etching, and a third module 957c performs ALD of bulk Mo using a molybdenum halide precursor.

[0211] Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate as described above with reference to Figure 8.

[0212] Referring to Figures 9 A and 9B, in various embodiments, a system controller 929 is employed to control process conditions during deposition. The controller 929 will typically include one or more memory devices and one or more processors. A processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. Such a system controller may be employed in control of any of the processes and apparatus described herein.

[0213] The controller 929 may control all the activities of the apparatus. The system controller 929 executes system control software, including sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other parameters of a particular process. Other computer programs stored on memory devices associated with the controller 929 may be employed in some embodiments.

[0214] Typically, there will be a user interface associated with the controller 929. The user interface may include a display screen, graphical software displays of the apparatus and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0215] System control logic may be configured in any suitable way. In general, the logic can be designed or configured in hardware and / or software. The instructions for controlling the drive circuitry may be hard coded or provided as software. The instructions may be provided by “programming.” Such programming is understood to include logic of any form, including hard coded logic in digital signal processors, application-specific integrated circuits, and other devices which have specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general-purpose processor. System control software may be coded in any suitable computer readable programming language.

[0216] The computer program code for controlling the Mo precursor pulses, hydrogen pulses, and argon flow, and other processes in a process sequence can be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. Compiled object code or script is executed by the processor to perform the tasks identified in the program. Also as indicated, the program code may be hard coded.

[0217] The controller parameters relate to process conditions, such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters are provided to the user in the form of a recipe and may be entered utilizing the user interface.

[0218] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 929. The signals for controlling the process are output on the analog and digital output connections of the deposition apparatus.

[0219] The system software may be designed or configured in many ways. For example, various chamber component subroutines or control objects may be written to control operation of the chamber components necessary to carry out the deposition processes in accordance with the disclosed embodiments. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0220] In some implementations, a controller 929 is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment,including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller 929, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0221] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0222] The controller 929, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller 929 may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming ofparameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. The parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by including one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0223] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a PVD chamber or module, a CVD chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0224] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0225] The controller 929 may include various programs. A substrate positioning program may include program code for controlling chamber components that are used to load the substrate onto a pedestal or chuck and to control the spacing between the substrate and other parts of the chamber such as a gas inlet. A substrate tilt and rotation program may include for tilt and rotation. A process gas control program may include code for controlling gas composition, flow rates, pulse times, and optionally for flowing gas into the chamber prior to deposition in order to stabilize the pressure in the chamber. A pressure control program may include code for controlling the pressure in the chamber by regulating, e.g., a throttle valve in the exhaust system of the chamber. A heater control program may include code for controlling the current to a heating unit that is used to heat thesubstrate. Alternatively, the heater control program may control delivery of a heat transfer gas such as helium to the wafer chuck.

[0226] Examples of chamber sensors that may be monitored during deposition include mass flow controllers, pressure sensors such as manometers, and thermocouples located in the pedestal or chuck. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain desired process conditions.

[0227] As described above, in some embodiments, oxidation or nitridation occurs via a plasma process. Examples of plasma apparatuses are described below.

[0228] A direct plasma (or plasma generated directly) is a plasma in which the plasma (electrons, neutral species, radicals, and positive ions at an appropriate concentration) resides in close proximity to the substrate surface during deposition, sometimes separated from the substrate surface by only a plasma sheath. Ions can play an important role in the direct plasma process. An apparatus for direct plasma treatment is described in Figure 8 below. In some embodiments, the plasma is generated remotely. A remote plasma (or plasma generated remotely) is one in which the plasma is generated at a distance from the substrate. The major reaction species may be radicals for plasma generated remotely. An apparatus for direct plasma treatment is described in Figure 10 below. Under some circumstances, there may be certain advantages of using a remote plasma instead of a direct plasma.

[0229] Figure 10 presents a schematic diagram of a remote plasma apparatus according to certain embodiments. The device 1000 includes a reaction chamber 1010 with a showerhead assembly 1020. Inside the reaction chamber 1010, a substrate 1030 rests on a stage or pedestal 1035. In some embodiments, the pedestal 1035 can be fitted with a heating / cooling element. A controller 1040 may be connected to the components of the device 1000 to control the operation of the device 1000. For example, the controller 1040 may contain instructions for controlling process conditions for the operations of the device 1000, such as the temperature process conditions and / or the pressure process conditions. In some embodiments, the controller 1040 may contain instructions for controlling the flow rates of precursor gas, co-reactant gas, source gas, and carrier gas. The controller 1040 may contain instructions for changing the flow rate of the co-reactant gas over time. In addition, or in the alternative, the controller 1040 may contain instructions for changing the flow rate of the precursor gas over time.

[0230] During operation, gases or gas mixtures are introduced into the reaction chamber 1010 via one or more gas inlets coupled to the reaction chamber 1010. In some embodiments, two or moregas inlets are coupled to the reaction chamber 1010. A first gas inlet 1055 can be coupled to the reaction chamber 1010 and connected to a vessel 1050, and a second gas inlet 1065 can be coupled to the reaction chamber 1010 and connected to a remote plasma source 1060. In embodiments including remote plasma configurations, the delivery lines for the precursors and the radical species generated in the remote plasma source are separated. Hence, the precursors and the radical species do not substantially interact before reaching the substrate 1030.

[0231] One or more radical species may be generated in the remote plasma source 1060 and configured to enter the reaction chamber 1010 via the gas inlet 1065. Any type of plasma source may be used in remote plasma source 1060 to create the radical species. This includes, but is not limited to, capacitively coupled plasmas, inductively coupled plasmas, microwave plasmas, DC plasmas, and laser-created plasmas. An example of a capacitively coupled plasma can be a radio frequency (RF) plasma. A high-frequency plasma can be configured to operate at 13.56 MHz or higher. Another example of such a RF remote plasma source 1060 may be one which can be operated at 440 kHz and can be provided as a subunit bolted onto a larger apparatus for processing one or more substrates in parallel. In some embodiments, a microwave plasma can be used as the remote plasma source 1060. A microwave plasma can be configured to operate at a frequency of 2.45 GHz. Gas provided to the remote plasma source may include hydrogen, nitrogen, oxygen, and other gases as mentioned elsewhere herein. In certain embodiments, oxygen is provided in a carrier such as hydrogen or argon gas. As an example, oxygen gas may be provided in a carrier at a concentration of at least 25% oxygen or 20 - 30% oxygen.

[0232] The precursors can be provided in vessel 1050 and can be supplied to the showerhead 1020 via the first gas inlet 1055. The showerhead 1020 distributes the precursors into the reaction chamber 1010 toward the substrate 1030. The substrate 1030 can be located beneath the showerhead 1020. It will be appreciated that the showerhead 1020 can have any suitable shape, and may have any number and arrangement of ports for distributing gases to the substrate 1030. The precursors can be supplied to the showerhead 1020 and ultimately to the substrate 1030 at a controlled flow rate.

[0233] The one or more radical species formed in the remote plasma source 1060 can be carried in the gas phase toward the substrate 1030. The one or more radical species can flow through a second gas inlet 1065 into the reaction chamber 1010. It will be understood that the second gas inlet 1065 need not be transverse to the surface of the substrate 1030. In certain embodiments, the second gas inlet 1065 can be directly above the substrate 1030 or in other locations. The distance between the remote plasma source 1060 and the reaction chamber 1010 can be configured toprovide mild reactive conditions such that the ionized species generated in the remote plasma source 1060 are substantially neutralized, but at least some radical species in substantially low energy states remain in the environment adjacent to the substrate 1030. Such low energy state radical species are not recombined to form stable compounds. The distance between the remote plasma source 1060 and the reaction chamber 1010 can be a function of the aggressiveness of the plasma (e.g., determined in part by the source RF power level), the density of gas in the plasma (e.g., if there’s a high concentration of hydrogen atoms, a significant fraction of them may recombine to form H2 before reaching the reaction chamber 1010), and other factors. In some embodiments, the distance between the remote plasma source 1060 and the reaction chamber 1010 can be between about 1 cm and 30 cm, such as about 5 cm or about 15 cm.

[0234] In some embodiments, a co-reactant, which is not the primary metal-containing precursor or a hydrogen radical, is introduced during the deposition reaction. In some implementations, the apparatus is configured to introduce the co-reactant through the second gas inlet 1065, in which case the co-reactant is at least partially converted to plasma. In some implementations, the apparatus is configured to introduce the co-reactant through the showerhead 1020 via the first gas inlet 1055. Examples of the co-reactant include oxygen, nitrogen, ammonia, carbon dioxide, carbon monoxide, and the like. The flow rate of the co-reactant can vary over time to produce a composition gradient in a graded film.

[0235] The controller 1040 may contain instructions for controlling process conditions for the operation of the device 1000. The controller 1040 will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. Instructions for implementing appropriate control operations are executed on the processor. These instructions may be stored on the memory devices associated with the controller 1040 or they may be provided over a network.

[0236] In certain embodiments, the controller 1040 controls all or most activities of the semiconductor processing device 1000 described herein. The controller 1040 may execute system control software including sets of instructions for controlling the timing, gas composition, gas flow rates, chamber pressure, chamber temperature, RF power levels, substrate position, and / or other parameters. Other computer programs, scripts, or routines stored on memory devices associated with the controller 1040 may be employed in some embodiments. In a multi-station reactor, the controller 1040 may comprise different or identical instructions for different apparatus stations, thus allowing the apparatus stations to operate either independently or synchronously.

[0237] In some embodiments, the controller 1040 may include instructions for performing operations such as flowing a metal-containing precursor through the first gas inlet 1055 into the reaction chamber 1010, providing one or more radical species of a source gas in a substantially low energy state from the remote plasma source 1060, flowing a co-reactant gas through the second gas inlet 1065 into the reaction chamber 1010, changing a flow rate of the co-reactant gas over time, and flowing the one or more radical species through the second gas inlet 1065 into the reaction chamber 1010 to react with the metal-containing precursor to form the thin metal film on the substrate 1030. In some implementations, the controller 1040 may include instructions for changing a flow rate of the metal-containing precursor over time.

[0238] In some embodiments, the apparatus may include a user interface associated with controller 1040. The user interface may include a display screen, graphical software displays of the apparatus and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0239] The computer program code for controlling the above operations can be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. Compiled object code or script is executed by the processor to perform the tasks identified in the program.

[0240] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller. The signals for controlling the process are output on the analog and digital output connections of the processing system.

[0241] In some embodiments, the plasma may be monitored in- situ by one or more plasma monitors. In one scenario, plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, plasma density and / or process gas concentration may be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters may be programmatically adjusted based on measurements from such in-situ plasma monitors. For example, an OES sensor may be used in a feedback loop for providing programmatic control of plasma power. It will be appreciated that, in some embodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0242] In general, the methods described herein can be performed on systems including semiconductor processing equipment such as a processing tool or tools, chamber or chambers, aplatform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. In general, the electronics are referred to as the controller, which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0243] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials (e.g., silicon carbide), surfaces, circuits, and / or dies of a wafer.

[0244] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer.In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0245] In addition to the metal deposition described herein, example systems may include a plasma etch chamber or module, a deposition chamber or module, , a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0246] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0247] Figure 11 depicts a cross-sectional side view of an example apparatus in accordance with disclosed embodiments. This apparatus may be used to perform any of the methods described herein, for example using the chemistry described herein. As detailed below, this apparatus 1100 is capable of rapidly and precisely controlling the temperature of a substrate, including performing thermal etching operations. The apparatus 1100 includes a processing chamber 1102, a pedestal 1104 having a substrate heater 1106 and a plurality of substrates supports 1108 configured to support a substrate 1118, and a gas distribution unit 1110.

[0248] The processing chamber 1102 includes sides walls 1112A, a top 1112B, and a bottom 1112C, that at least partially define the chamber interior 1114, which may be considered a plenum volume. It may be desirable in some embodiments to actively control the temperature of the processing chamber walls 1112A, top 1112B, and bottom 1112C

[0249] This active temperature control of the chamber’s surfaces may be achieved by using chamber heaters 1116A-1116C to heat the chamber walls 1112A, the top 1112B, and the bottom 1112C. e chamber heaters 1116A-1116C are configured to generate heat in order to cause the interior surfaces of each of the chamber walls 1112A, the top 1112B, and the bottom 1112C to the desired temperature, which may range between about 80°C and about 130°C, including about 90°C of about 120°C, for instance.

[0250] The apparatus 1100 may also be configured to perform processing operations at or near a vacuum, such as at a pressure of about 0.1 Torr to about 10 Torrs. This may include a vacuum pump 1184 configured to pump the chamber interior 114 to low pressures, such as a vacuum having a pressure of about 0.1 Torr to about 10 Torr.

[0251] As illustrated in Figure 11, the pedestal 1104 may further include a pedestal heater 1144 inside of the pedestal 1104 that is configured to heat the exterior surfaces of the pedestal 104, including its sides 1142A and bottom 1142B. The pedestal heater 1144 may include one or more heating elements, such as one or more resistive heating elements and fluid conduits in which a heating fluid is configured to flow. In some instances, the pedestal cooler and the pedestal heater may both have fluid conduits that are fluidically connected to each other such that the same heat transfer fluid may flow in both the pedestal cooler and the pedestal heater. In these embodiments, the fluid may be heated to between 50°C and 130°C including about 90°C and 120°C.

[0252] In certain embodiments, the temperature of the substrate can be rapidly and precisely controlled by thermally floating, or thermally isolating, the substrate within the chamber. The heating and cooling of a substrate is directed at both the substrate’s thermal mass and the thermal masses of other items in contact with the substrate. This thermal floating is configured to position the substrate so that it has minimal thermal contact (which includes direct and radiation) with other bodies in the chamber.

[0253] The pedestal 1104 is therefore configured, in some embodiments, to support the substrate 1118 by thermally floating, or thermally isolating, the substrate within the chamber interior 1114. The pedestal’s 1104 plurality of substrate supports 1108 are configured to support the substrate 1118 such that the thermal mass of the substrate 1118 is reduced as much as possible to the thermal mass of just the substrate 1118. Each substrate support 1108 may have a substrate support surface 1120 that provides minimal contact with the substrate 1118.

[0254] The substrate supports are also configured to prevent the substrate from being in contact with other elements of the pedestal, including the pedestal’s surfaces and features underneath thesubstrate. In some embodiments, these substrate supports are stationary and fixed in position; they are not lift pins or a support ring.

[0255] In some embodiments, the pedestal is also configured to move vertically. This may include moving the pedestal such that a gap 1186 between a faceplate 1176 of the gas distribution unit 1110 and the substrate 1118 is capable of being in a range of 2 mm and 70 mm. As provided in more detail below, moving the pedestal vertically may enable active cooling of the substrate as well as rapid cycling time of processing operations, including flowing gas and purging, due to a low volume created between the gas distribution unit 1110 and the substrate 1118. This movement may also enable the creation of a small process volume between the substrate and the gas distribution unit which can result in a smaller purge and process volume and thus reduce purge and gas movement times and increase throughput.

[0256] The gas distribution unit 1110 is configured to flow process gases, which may include liquids and / or gases, such as a reactant, modifying molecules, converting molecules, or removal molecules, onto the substrate 1118 in the chamber interior 1114. As seen in Figure 11, the gas distribution unit 1110 includes one or more fluid inlets 1170 that are fluidically connected to one or more gas sources 1172 and / or one or more vapor sources 1174. In some embodiments, the gas lines and mixing chamber may be heated to prevent unwanted condensation of the vapors and gases flowing within. These lines may be heated to at least about 80°C, 90°C, or 120°C. The one or more vapor sources may include one or more sources of gas and / or liquid which is vaporized. The vaporizing may be a direct inject vaporizer, a flow over vaporizer, or both. The gas distribution unit 1110 also includes the faceplate 1176 that includes a plurality of through-holes 1178 that fluidically connect the gas distribution unit 1110 with the chamber interior 1114. These through- holes 178 are fluidically connected to the one or more fluid inlets 1170 and also extend through a front surface 1177 of the faceplate 1176, with the front surface 1177 configured to face the substrate 1118. In some embodiments, the gas distribution unit 1110 may be considered a top plate and in some other embodiments, it may be considered a showerhead.

[0257] The through-holes 1178 may be configured in various ways in order to deliver uniform gas flow onto the substrate. In some embodiments, these through-holes may all have the same outer diameter, such as between about 0.03 inches and 0.05 inches, including about 0.04 inches (1.016 mm). These faceplate through-holes may also be arranged throughout the faceplate in order to create uniform flow out of the faceplate.

[0258] Referring back to Figure 11, the gas distribution unit 1110 may also include a unit heater 1180 that is thermally connected to the faceplate 1176 such that heat can be transferred betweenthe faceplate 1176 and the unit heater 1180. The unit heater 1180 may include fluid conduits in which a heat transfer fluid may be flowed. Similar to above, the heat transfer fluid may be heated to a temperature range of about 20°C and 120°C, for example. In some instances, the unit heater 1180 may be used to heat the gas distribution unit 1110 to prevent unwanted condensation of vapors and gases; in some such instances, this temperature may be at least about 90°C or 120°C.

[0259] In some embodiments, the apparatus 1100 may include a mixing plenum for blending and / or conditioning process gases for delivery before reaching the fluid inlets 1170. One or more mixing plenum inlet valves may control introduction of process gases to the mixing plenum. In some other embodiments, the gas distribution unit 1110 may include one or more mixing plenums within the gas distribution unit 1110. The gas distribution unit 1110 may also include one or more annular flow paths fluidically connected to the through-holes 1178 which may equally distribute the received fluid to the through-holes 1178 in order to provide uniform flow onto the substrate.

[0260] The apparatus 1100 may also include one or more additional non-contact sensors for detecting the temperature of the substrate. One such sensor may be a new pyrometer that is capable of detecting numerous temperature ranges of a silicon substrate. It is desirable to detect the temperature of substrates having different treatments at different temperatures ranges at which processing operations may occur, such as under about 200°C, greater than about 200°C and less than about 600°C, or above 600°C.

[0261] The foregoing describes implementation of disclosed embodiments in a single or multichamber semiconductor processing tool. The apparatus and process described herein may be used in conjunction with lithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, photovoltaic panels, and the like. Typically, though not necessarily, such tools / processes will be used or conducted together in a common fabrication facility. Lithographic patterning of a film typically includes some or all of the following steps, each step provided with a number of possible tools: (1) application of photoresist on a workpiece, i.e., substrate, using a spin-on or spray-on tool; (2) curing of photoresist using a hot plate or furnace or UV curing took (3) exposing the photoresist to visible or UV or x-ray light with a tool such as a wafer stepper; (4) developing the resist so as to selectively remove resist and thereby pattern it using a tool such as a wet bench; (5) transferring the resist pattern into an underlying film or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

Claims

CLAIMSWhat is claimed is:

1. A method for processing a featured substrate comprising:(a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening and molybdenum-containing material therein, each feature having a depth from the feature opening to a surface of the molybdenum-containing material therein, wherein a feature-to-feature depth is characterized by a feature-to-feature depth non-uniformity;(b) oxidizing a portion of the molybdenum-containing material to form a molybdenum oxide: and(c) selectively etching the molybdenum oxide with respect to the molybdenum-containing material to thereby expose an underlying molybdenum-containing material and reduce the feature-to-feature depth non-uniformity.

2. The method of claim 1, wherein (b) comprises exposing the featured substrate to an oxygen-containing plasma.

3. The method of claim 2, wherein the oxygen-containing plasma is generated from a process gas comprising oxygen (O2).

4. The method of claim 3, wherein the process gas further comprises one or more of hydrogen (H2) gas and argon gas.

5. The method of claim 3, wherein the process gas is at least 20% (vol.) O2.

6. The method of claim 5, wherein the process gas is between 20 and 30% (vol) O2.

7. The method of claim 2, wherein the oxy gen-containing plasma is ignited using a capacitively coupled plasma generator.

8. The method of claim 2, wherein the oxy gen-containing plasma is ignited using an inductively coupled plasma generator.

9. The method of claim 2, wherein the oxygen-containing plasma is generated in a remote chamber.

10. The method of claim 2, wherein the oxy gen-containing plasma is ignited using a power between 150 W and 1000 W.

11. The method of claim 1, wherein (b) comprises exposing the substrate to a thermal soaking process using at least one of ozone, oxygen gas, and water.

12. The method of claim 1, wherein (b) forms a molybdenum oxide thickness in each feature between 5 and 25 nm.

13. The method of claim 1, wherein (b) is performed at a substrate temperature between 225 °C and 400°C.

14. The method of claim 1, wherein (b) is performed at a pressure between 0.4 torr and 10 torr.

15. The method of claim 1, further comprising repeating (b) one to forty times.

16. The method of claim 1, wherein (c) comprises exposing a layer of molybdenum oxide to one or more of: molybdenum pentachloride (M0CI5), chlorine (Ch), boron trichloride (BCI3), carbon tetrachloride (CCI4), hydrogen fluoride (HF), tungsten hexafluoride (WFe), and nitrogen trifluoride (NF3).

17. The method of claim 1, wherein the etch selectivity between the molybdenum oxide and the molybdenum-containing material in (c) is at least 100: 1.

18. The method of claim 1, wherein the etch selectivity between the molybdenum oxide and a molybdenum-containing layer in (c) is at least 500: 1.

19. The method of claim 1, wherein the molybdenum-containing material in (a) is deposited on a titanium nitride plug.

20. The method of claim 1, further comprising selectively depositing the molybdenum- containing material on a metal nitride plug by exposing the titanium nitride plug to amolybdenum halide precursor and exposing the molybdenum halide precursor to reducing agent to form the molybdenum-containing material.

21. The method of claim 20, wherein the metal nitride plug comprises a titanium nitride.

22. The method of claim 20, wherein the molybdenum halide precursor is molybdenum pentachloride (M0CI5).

23. The method of claim 20, wherein the reducing agent is hydrogen (H2).

24. The method of claim 1 further comprises depositing the molybdenum-containing material in the features by atomic layer deposition.

25. The method of claim 1, further comprises (c) depositing additional molybdenum- containing material over the underlying molybdenum-containing material to fill the plurality of features.

26. The method in claim 1, wherein the (b) and (c) are repeated one or more times.

27. The method of claim 1, prior to (b) removing a native oxide on the molybdenum-containing material.

28. A method for processing a featured substrate comprising:(a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening, a feature depth, and molybdenum-containing material deposited therein, wherein the molybdenum-containing material is deposited to a nonuniform depth from the feature opening;(b) oxidizing a portion of the molybdenum-containing material to form a molybdenum oxide; and(c) converting the molybdenum oxide to the molybdenum-containing material.

29. The method of claim 28, wherein (c) comprises soaking the featured substrate in hydrogen gas.

30. The method of claim 28, further comprises removing a byproduct, wherein the byproduct is fluorine or chlorine.

31. The method as in any one of the preceding claims, wherein resistivity of the molybdenum- containing material is decreased by 20 to 30%.

32. A method for processing a featured substrate comprising:(a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening, a feature depth, and molybdenum-containing material deposited therein, wherein the molybdenum-containing material is deposited to a nonuniform depth from the feature opening;(b) nitriding a portion of the molybdenum-containing material to form a molybdenum nitride;(c) selectively etching the molybdenum nitride; and(d) exposing an underlying molybdenum-containing material having a uniform depth from the feature opening.

33. A method for processing a featured substrate comprising:(a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening and a feature bottom, wherein a layer of titanium nitride is deposited on the feature bottom;(b) oxidizing a portion of the titanium nitride to form a titanium oxynitride;(c) selectively etching the titanium oxynitride; and(d) depositing a molybdenum-containing material in each feature.

34. The method of 33, wherein (b) comprises exposing the portion of titanium nitride to an oxygen-containing plasma.

35. The method of claim 33, wherein the oxygen-containing plasma is generated from a process gas comprising oxygen (O2).

36. The method of claim 34, wherein the process gas further comprises one or more of hydrogen (H2) gas and argon gas.

37. The method of claim 32, wherein (b) comprises exposing the titanium nitride to a hydrogen-containing plasma.

38. The method of claim 36, wherein the hydrogen-containing plasma is H2 plasma.

39. The method of claim 32, wherein (c) comprises exposing the titanium oxynitride to at least one of boron trichloride (BCh), hydrogen fluoride (HF), tungsten hexafluoride (WFe), and nitrogen trifluoride (NF3).

40. A method of processing a featured substrate comprising:(a) providing a substrate having a plurality of features spaced apart, each feature having a feature opening and a feature bottom, wherein a titanium nitride is deposited on the feature bottom, and wherein the titanium nitride comprises titanium oxynitride;(b) selectively etching the titanium oxynitride; and(c) depositing a molybdenum-containing material in each feature.

41. The method of claim 39, wherein (b) comprises exposing the titanium oxynitride to at least one of boron trichloride (BCh), hydrogen fluoride (HF), tungsten hexafluoride (WFe), and nitrogen trifluoride (NF3).

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