Molybdenum deposition

Abstract

Methods and related apparatus for deposition of molybdenum-containing films are described.

Description

MOLYBDENUM DEPOSITIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] 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

[0002] 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 a CVD process using tungsten hexafluoride (WFe). However, as devices shrink and more complex patterning schemes are utilized in the industry, deposition of thin tungsten films 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 is particularly challenging.

[0003] The background description provided herein is for the purposes of generally presenting the context of the 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] One aspect of the disclosure relates to method comprising: providing a feature to be filled with molybdenum; performing a deposition process to deposit molybdenum in the feature, the deposition process comprising exposing the feature to a process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride, wherein the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.01%.

[0005] In some embodiments, the deposition process is a chemical vapor deposition process.In some embodiments, the deposition process is an atomic layer deposition process further comprising, after exposing the feature to the process gas, exposing the feature to a reducing agent dose comprising hydrogen with no molybdenum hexafluoride.

[0006] In some embodiments, the feature comprises a conductive surface and a dielectric surface and further wherein the molybdenum is selectively deposited on the conductive surface.

[0007] In some embodiments, the method further comprises prior to the deposition process, depositing a molybdenum nucleation layer in the feature.

[0008] In some such embodiments, depositing the molybdenum nucleation layer comprises exposing the feature to sequential doses of a) a nucleation layer process gas comprising molybdenum hexafluoride and b) a non-hydrogen reducing agent.

[0009] In some such embodiments, the concentration of molybdenum hexafluoride in the nucleation layer process gas is higher than the concentration of molybdenum hexafluoride in the process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride.

[0010] In some embodiments, the method further comprises treating the feature prior to performing the deposition process by exposing it to a metal fluoride.

[0011] In some such embodiments, the metal fluoride is tungsten hexafluoride or molybdenum hexafluoride.

[0012] In some embodiments, the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.004%.

[0013] Another aspect of the disclosure relates to a method comprising: providing a feature to be filled with molybdenum; performing a deposition process to deposit molybdenum in the feature, the deposition process comprising exposing the feature to a plasma generated from a process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride, wherein the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.01%.

[0014] In some such embodiments, the deposition process is a plasma-enhanced chemical vapor deposition process.

[0015] In some embodiments, the deposition process is a plasma-enhanced atomic layer deposition process further comprising, after exposing the feature to the process gas, exposing the feature to a hydrogen plasma.

[0016] In some embodiments, the feature comprises a conductive surface and a dielectric surface and further wherein the molybdenum is deposited on the conductive surface and the dielectric surface.

[0017] In some embodiments, the method further comprises, prior to the deposition process,depositing a molybdenum nucleation layer in the feature.

[0018] In some such embodiments, depositing the molybdenum nucleation layer comprises exposing the feature to sequential doses of a) a nucleation layer process gas comprising molybdenum hexafluoride and b) a non-hydrogen reducing agent.

[0019] In some embodiments, the concentration of molybdenum hexafluoride in the nucleation layer process gas is higher than the concentration of molybdenum hexafluoride in the process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride.

[0020] In some embodiments, the method further comprises treating the feature prior to performing the deposition process by exposing it to a metal fluoride.

[0021] In some embodiments, the metal fluoride is tungsten hexafluoride or molybdenum hexafluoride.

[0022] In some embodiments, the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.004%.

[0023] These and other features are discussed below with reference to the Figures.BRIEF DESCRIPTION OF DRAWINGS

[0024] Figures 1A and IB are schematic examples of material stacks that include Mo layers according to various embodiments.

[0025] Figures 2A-2L are schematic examples of various structures into which molybdenum may be deposited in accordance with disclosed embodiments.

[0026] Figure 3 shows additional schematic examples of structures into which molybdenum may be deposited in accordance with disclosed embodiments.

[0027] Figure 4 shows a schematic example of a molybdenum-on-molybdenum integration scheme.

[0028] Figure 5 is a flow diagram showing operations in a method of pre-treating a substrate.

[0029] Figure 6 shows deposition of molybdenum on various surfaces using molybdenum hexafluoride and hydrogen.

[0030] Figure 7 is a flow diagram showing operations in a method of selective deposition of molybdenum in a feature.

[0031] Figure 8 is a flow diagram showing operations in a method of reducing selectivity in a feature.

[0032] Figure 9 shows cross-sectional representations of a feature during deposition with net deposition at the bottom of the feature and net etch at the top of the feature.

[0033] Figure 10 shows representations of a 3D NAND structure after operations in adeposition, etch, deposition sequence.

[0034] Figure 11 shows examples of deposition-etch-deposition and deposition-inhibition- deposition processes on a vertically-oriented feature.

[0035] Figures 12, 13A, and 13B show apparatus that may be used to implement the methods described herein.DETAILED DESCRIPTION

[0036] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all 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.

[0037] The subscripts “x” and “y” are used throughout the disclosure to denote a number greater than 0 that forms a stable compound. However, it should be noted that the lack of an “x” or other subscript (e.g., in titanium nitride (TiN) or titanium oxynitride (TiON)) does not imply a particular atomic ratio.

[0038] Provided herein are methods of deposition molybdenum (Mo) films that may be used for logic and memory applications. The Mo films may be deposited in semiconductor substrate features such as vias and trenches. The Mo films may be deposited to line features as liner layers and / or to fill features.

[0039] In the description below, reference is made to Mo films. However, the methods may also be used to deposit Mo-containing films, including nitrides, oxides, oxynitrides, etc. Elemental Mo films (also referred to as Mo metal or Mo films) are understood to be molybdenum films that have less than 1% (mol) impurities.

[0040] For some applications, molybdenum offers several benefits over other metals such as cobalt (Co), ruthenium (Ru), and tungsten (W): (i) barrier-less and liner-less molybdenum film 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.

[0041] Figures 1A and IB are schematic examples of material stacks that include Mo layersaccording to various embodiments. Figures 1A and IB illustrate the order of materials in examples of stacks and may be used with any appropriate architecture and application, as described further below. Figure 1A shows a first material stack 111 featuring a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 may be a silicon or other semiconductor wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semi-conducting material deposited thereon. In some embodiments, the substrate 102 may be or include silicon (Si) or silicon germanium (SiGe). The methods may also be applied to form metallization stack structures on other substrates, such as glass, plastic, and the like.

[0042] 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 surface.

[0043] 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 (SiO2), 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 an adhesion layer, for example. A diffusion barrier is a layer that prevents diffusion of species between layers. An adhesion layer is a layer that promotes adhesion of a layer to an underlying layer. Examples of diffusion barrier and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tantalum nitride (TaN), tungsten (W), tungsten nitride (WN), tungsten / tungsten nitride (W / 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 include multiple bulk layers deposited at different conditions. The molybdenum layer 108 may or may not include a molybdenum nucleation 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 the molybdenum layer 108.

[0044] 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 108 deposited directly on the dielectric layer 104, without an intervening diffusion barrier or adhesion layer. Themolybdenum 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 uOhm-cm at 60 angstroms thickness and less than 15 uOhm-cm at 200 angstroms thickness.

[0045] In some embodiments, a stack (not shown) may include the 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(l'1-cm4at 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 a metal nitride layer (e.g., TiN, WN, or MoN). In still some other embodiments of a stack (not shown), the stack may include a substrate and a molybdenum layer deposited directly on the substrate, including directly on a semiconducting surface, on a dielectric surface, or on a conductive surface. Figures 1A and IB illustrate examples of the order of materials in a particular stack and may be used with any appropriate architecture and application, with examples described further below.

[0046] 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 material, such as dielectric, conducting, or semiconducting material deposited thereon. The methods are not limited to semiconductor substrates and may be performed to fill any feature with molybdenum.

[0047] 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 feature 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.

[0048] 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 a silicon oxide or silicon nitride material. Insome embodiments disclosed herein, the conformal barrier layer 206 is TiN or a 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.

[0049] The bWL structure shown in Figure 2A is one example of an architecture that includes a molybdenum fill layer. During fabrication of the bWL, molybdenum is deposited into a feature that may be defined by an etched recess in the silicon substrate 202 that is conformally lined with layers 206 and / or 204, if present.

[0050] 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 feature 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 and 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 features having vertical axes and horizontally-oriented features having horizontal axes. The underlayer 203 can be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination of thereof, or any other applicable material. Nonlimiting examples of underlayers can include dielectric layers and conducting layers. Examples of dielectric materials include oxides, such as SiCh and AI2O3; 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 under-layer is tungsten-free. In some embodiments, the underlayer is molybdenum-free.

[0051] 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 200A 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 feature 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.

[0052] Figure 2C shows an example of a vertical feature 201 that has a re-entrant profile. A re-entrant profile is a profile that narrows from a 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. Like Figure 2B, the underlayer 213 can be a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination of thereof, or any other applicable material. Non-limiting examples of under-layers can include dielectric layers and conducting layers. The underlayer 213 forms an overhang 215 such that the underlayer 213 is thicker near the opening of the vertical feature 201 than inside the vertical feature 201.

[0053] In some implementations, features having 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 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).

[0054] Horizontal features, such as in 3-D 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 word line in a 3-D 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 3-D NAND structure 210 (formed on a silicon substrate 202) having 3-D NAND stacks (left 225 and right 226), central vertical structure 230, and a plurality of stacked horizontal wordline features 220 with openings 222 on opposite sidewalls 240 of central vertical structure 230. Note that Figure 2F displays two “stacks” of the exhibited 3-D NAND structure 210, which together form the “trench-like” central vertical structure 230. However, in certainembodiments, 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 stacks forming a central vertical structure 230, like that explicitly illustrated in Figure 2F. In this embodiment, the horizontal wordline features 220 are 3-D 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 features 220 present in both the 3-D NAND stacks 225 and 226 shown in Figure 2F (i.e., the left 3-D NAND stack 225 and the right 3-D NAND stack 226) are also accessible from the other sides of the stacks (far left and far right, respectively) through similar vertical structures formed by additional 3-D NAND stacks (to the far left and far right, but not shown). Each 3-D NAND stack 225, 226 contains a stack of wordline features that are fluidically accessible from both sides of the 3-D NAND stack through a central vertical structure 230. In the example schematically illustrated in Figure 2F, each 3-D NAND stack contains 6 pairs of stacked wordlines. However, a 3-D NAND memory layout may contain any number of vertically stacked pairs of wordlines.

[0055] The wordline features in a 3-D 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 may be vertically stacked in such a 3-D 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 horizontal wordline features, and so forth (the listed ranges understood to include e the recited endpoints).

[0056] Figure 2G presents a cross-sectional top-down view of the same 3-D 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 3-D NAND structure 210. In some embodiments, the pillars 255 are formed from a polysilicon material and are structurally and functionally significant to the 3-D 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 openings 222 to wordline features 220. Fluidic accessibility of wordline features 220 from the central vertical structure230 via openings 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 material. The structure of wordline features 220 and the challenge of uniformly filling them with molybdenum material due to the presence of pillars 255 is further illustrated in Figures 2H, 21, and 2 J.

[0057] Figure 2H exhibits a vertical cut through a 3-D NAND structure like 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 features 220. Figure 21 also schematically illustrates void 275, but in this figure illustrated via a horizontal cut through pillars 255, like the horizontal cut exhibited in Figure 2G. Figure 2J illustrates the accumulation of molybdenum material around the constrictionforming pillars 255, the accumulation resulting in the pinch-off of openings 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 wordline features 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 partially 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 2-D rendering of the 3-D features of the structure of the pillar constrictions shown in Figure 21, thus illustrating constrictions that would be seen in a plan view rather than in a cross-sectional view.)

[0058] 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.

[0059] Figures 2K and 2L show examples of an 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 feature261 and filled feature 265 that exhibits 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 features 261 may be generally V-shaped, as shown in feature 283, having sloped 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. This phenomenon is illustrated in Figure 2L and may be characterized as “zipping up” the feature. As the feature 283 is filled, more force is exerted from a center axis 299 of the 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.

[0060] Provided below are method of depositing molybdenum and molybdenum-containing films. In some embodiments, the methods include filling features with molybdenum. As described above, molybdenum offers several benefits over other metals. Examples of feature fill for horizontally-oriented and vertically-oriented features are described below. It should be noted that in at least most cases, the examples are applicable to both horizontally-oriented and vertically-oriented features. Horizontally-oriented features generally refer to features oriented such that the feature axis is parallel to the plane of the substrate surface. Vertically-oriented features generally refer to features oriented such that the feature axis is orthogonal to the plane of the substrate surface.

[0061] In some embodiments, the methods are used to fill features to contact an underlying metal. An example of such a feature is shown in Figure 3. At 301, an unfilled feature 312 is shown. The unfilled feature 312 is formed in an oxide layer 305 and is to be filled with Mo to contact an underlying metal 303. The unfilled feature 312 is defined by sidewall surfaces 315 and bottom surface 317. According to various embodiments, the sidewall surfaces 315 and the bottom surface 317 may be the same or dissimilar materials. In some embodiments, the oxide layer 305 may be exposed to form the sidewall surfaces 315. Similarly, the underlying metal303 may be exposed to form the bottom surface 317. In some embodiments, surface oxidation may result in the bottom surface 317 being a metal oxide. In some embodiments, a liner layer (not shown) may be formed on the sidewall and / or bottom of the feature to form the sidewall surfaces 315 and / or bottom surface 317. Examples of liner layers include TiN, WN, and WCN. In some embodiments, a liner layer may be a molybdenum-containing liner layer such as a molybdenum nitride (MoN) layer.

[0062] In some embodiments, the sidewall surfaces 315 and bottom surface 317 are different. In a subsequent deposition operation, Mo may be deposited at conditions under which it preferentially nucleates on the bottom surface 317. This can promote bottom- up fill and prevent the formation of voids.

[0063] Examples of underlying metals and / or bottom surfaces include TiN, titanium aluminum carbide (TiAlC), W, Co, Mo, Ru, Cu, nickel (Ni), iridium (Ir), rhodium (Rh), tantalum (Ta), and titanium (Ti)and tantalum nitride (TaN).

[0064] The methods described herein address various challenges that occur as feature size decreases. For example, void-free gap fill becomes more challenging in small features due to deeper features, re-entrant profiles near the feature openings, and / or insufficient growth selectivity between feature bottom metal surfaces and sidewall dielectric surfaces. Smaller features can lead to more frequent pattern misalignment. An example of a misaligned feature is shown at 350 in which the unfilled feature 312 is not centered over the underlying metal 303. As a result, the bottom surface 317 includes metal and dielectric material.

[0065] In some embodiments, the methods may be used in molybdenum-on-molybdenum integration schemes. An example of such an integration scheme is shown in Figure 4. A layer 401 includes dielectric 402 and Mo 403. An etch stop layer (ESL) 404 is disposed over the layer 401. The ESL 404 may be SiN, for example. A dielectric layer 405 is deposited over the ESL 404. The dielectric layer 405 is then patterned and etched, with the etch stopping at the ESL 404 (not shown). The ESL 404 is then removed from the feature 412 forming the unfilled feature 412.

[0066] A Mo-containing layer 410 may be formed at the surface of Mo 403 during the previous processing operations. The Mo-containing layer 410 is generally an amorphous layer. It is relatively thin, e.g., on the order of 0.5 nm to 3 nm. It may contain various impurities such as oxygen, nitrogen, and / or other halogens. While surface oxidation can be removed by a hydrogen (H2) plasma, the Mo-containing layer 410 is generally resistant to H2 plasma. If left in the device, it can cause higher resistance at the interface between Mo 403 and the subsequently deposited Mo film.Pre-treatment

[0067] Aspects of the disclosure relate to a surface treatment performed prior to deposition of Mo in a feature. According to various embodiments, the surface treatment involves exposure to a molybdenum halide. In some embodiments, the molybdenum halide is provided without a co-reactant, and no deposition occurs. In some embodiments, the molybdenum halide is provided with a co-reactant. A thin layer of Mo may be deposited.

[0068] Figure 5 is a process diagram showing operations in a method of pretreating a substrate. In an operation 501, a substrate having a surface to be treated is provided to a processing chamber. This can involve introducing the substrate to the processing chamber, or if the substrate is in the chamber from a prior processing operation, maintaining the substrate in the chamber. In some embodiments, operation 501 can involve moving the substrate from one station to another of a multi- station chamber.

[0069] The treatment is effective to remove surface impurities. The surface to be treated may be an elemental metal surface, e.g., a tungsten (W), molybdenum (Mo), cobalt (Co), copper (Cu), ruthenium (Ru), or titanium (Ti) surface. The pretreatment removes native oxides and / or other impurities such as carbon and nitrogen. In some embodiments, non-dielectric metallic (metal-containing) surfaces may be treated. For example, a titanium nitride film may have some surface oxide due to air exposure. The treatment may be used to remove the oxide, leaving a titanium nitride film. Similarly, oxide or other impurities may be removed from a titanium silicide film.

[0070] In some embodiments, the surface is part of a feature with examples discussed above with reference to Figures 1-4. Such features can also include dielectric surfaces such as dielectric sidewall surfaces. The surface treatment may inhibit growth on the dielectric surfaces, enhancing selectivity during subsequent deposition on the conductive or other metalcontaining surfaces. In some embodiments, the feature as provided includes a Mo-containing layer as described above. The surface treatment can remove this layer, yielding a clean Mo surface for deposition and Mo-Mo interconnect formation.

[0071] In operation 503, the process chamber is evacuated. This operation may be omitted in some embodiments but can be performed that the subsequent exposure to the metal halide is performed without exposure to oxygen, nitrogen, or other source of impurities.

[0072] Then, in operation 505, the substrate is exposed to a metal halide. This is generally a thermal, non-plasma process. In some embodiments, a molybdenum halide compound is used. Molybdenum halides 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 MoXzprecursorsinclude molybdenum fluoride (MoFe). In some embodiments, a molybdenum chloride is used. Molybdenum fluorides are given by the formula MoClx, where x is 2, 3, 4, 5, or 6, and include molybdenum dichloride (MoCh), molybdenum trichloride (MoCh), molybdenum tetrachloride (M0CI4), molybdenum pentachloride (M0CI5), and molybdenum hexachloride (MoCh). In some embodiments, M0CI5 or MoCh are used. 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.

[0073] If used, MoFe may be delivered at relatively low concentrations, e.g., at or less than 0.01%. This is generally higher than used during deposition using MoFe, but low enough to facilitate selective removal of native oxides and impurities over the etching the underlying metal surface. It also is low enough to prevent fluorine incorporation.

[0074] In some embodiments, a tungsten halide is used. Tungsten halides are given by the formula WXZ, 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 WXZprecursors include tungsten hexafluoride (WFe). WF6can be useful in that it is effective to remove surface oxides, nitrides, and carbides from a metal surface without etching the metal. In some embodiments, WFe or MoFe is used for ease of delivery.

[0075] Temperatures for the pre-treatment may be relatively low, e.g., in the range of 200°C to 400°C. Maintaining a temperature less than 400°C can help with selectively removing native oxides and / or nitrogen and carbon impurities with reference to the underlying metal.Molybdenum Deposition

[0076] Deposition of molybdenum as described herein involves reacting a Mo-containing precursor, also referred to as a molybdenum precursor. In some embodiments, a molybdenum halide compound MoXzas described above is used. In methods including surface treatment using a molybdenum halide compound, the same or different compound may be used for deposition.

[0077] A feature may be filled with molybdenum by atomic layer deposition (ALD) or chemical vapor deposition (CVD). Thermal ALD or plasma enhanced ALD (PEALD) may be used. Similarly, thermal CVD or plasma enhanced CVD (PECVD) may be used.

[0078] In some embodiments, a molybdenum oxyhalide precursor is used. Molybdenum oxyhalide precursors are given by the formula MoOyXz, where X is a halogen (fluorine (L), 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 includemolybdenum dichloride dioxide (MOO2CI2), molybdenum tetrachloride oxide (MoOCU), molybdenum tetrafluoride oxide (M00F4), molybdenum difluoride dioxide (MOO2F2) molybdenum dibromide dioxide (MoO2Br2), and the molybdenum iodides MOO2I, and MO4O11I. 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.

[0079] 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 (SiFE), diborane (B2H6), germane (GeFE), ammonia (NH3), and hydrazine (N2H4).

[0080] In some embodiments, the Mo precursor is a molybdenum fluoride (MoFx) compound, also referred to as a molybdenum fluoride precursor or MoFxprecursor. Molybdenum chloride precursors are given by the formula MoFx, where x is 4, 5, or 6, and include molybdenum tetrafluoride (M0F4), molybdenum pentafluoride (M0F5), and molybdenum hexafluoride (MOF6).

[0081] MoFe can be advantageous as it has a boiling point of 34°C. Being a gas at standard pressure and 35°C allows MoFe to be delivered through a mass flow controller (MFC) at room temperature, without heating and without condensing and forming particles. However, MoFe is an aggressive etchant and exposure to MoFe during a process can result in etching instead of or in addition to Mo deposition. In some embodiments, deposition using MoFe involves providing a flow of MoFe in a process gas with the MoFe at a molar concentration of 0.01% or less. Concentration may be significantly lower in some embodiments, for example, 0.008% or less, 0.005% or less, or 0.004% or less. These values can also be expressed as parts per million (ppm) of a gas: 100 ppm (100 MoFe molecules per 1 million gas particles (atoms, molecules)) or less, 80 ppm or less, or 40 ppm or less. At temperatures between 200°C and 650°C, for example, a molar concentration at or below 0.004% results in CVD deposition when flowed with H2 and argon. Higher temperatures may be used to favor the deposition reaction and allow higher concentrations of MoFe, e.g., up to 0.01%. In some embodiments, concentrations may be 0.0039% or .0035% or less. In some embodiments, the MoFe concentration is at least 0.00004% or at least 0.0001%. Concentration may be very low with an exposed metal surface to grow on, for example.

[0082] Deposition using MoFe with H2 as reducing agent occurs only at unusually lowconcentration. As an example, for 0.5 standard cubic centimeters per minute (seem) of MoFe, a total flow rate of 13,500 seem may be used, for a MoFe concentration of 0.0037%. Deposition using metal halides and hydrogen generally involves much higher concentrations. For example, deposition of molybdenum using molybdenum hexachloride and hydrogen can be performed using concentrations 5 to 10 times higher than those used for MoFe.

[0083] In some embodiments, MoFe may be used at higher concentrations and lower temperatures with a reducing agent that is stronger than that of hydrogen. Lower temperatures can reduce or prevent etching with MoFe; however, at low temperatures Fh may not result in deposition. Stronger reducing agents such silane, disilane, polysilanes and diborane may be used for deposition at lower temperatures (e.g., below 200°C). The resulting films may not be pure molybdenum and in some cases are more resistive than those deposited using Fh as the reducing agent. For these reasons they may not be appropriate for some applications.

[0084] 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, MoFe is flowed into the chamber with a reactant, such as Fh. In this example, the wafer is simultaneously exposed to the precursor and reactant, which react and fill features with Mo.

[0085] 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, Fh 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.

[0086] 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 gas that may be used to generate plasma may be a hydrogen-containing gas, such as Fh, nitrogen-containing 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. In a plasma-enhanced CVD (PECVD) process, a mixture including the molybdenum precursor and reactant may be fed into the plasma generator. For direct plasmas in the chamber, the mixture may be fed into the chamber with a plasma generated between electrodes (e.g., the showerhead and a pedestal) in the chamber. Argon or other inert gas can be used as a carrier gas and / or diluent.

[0087] For example, argon may be used as a carrier gas for MoFe to be mixed with Fh prior toentering the showerhead. H2 may be flowed with a small amount of argon or other inert gas. The concentration of MoFe in the mixture is as described above (100 ppm or less, etc.). According to various embodiments, H2 is at least about 90% of the gas, with the balance argon or other inert gas. PECVD may be used to deposit Mo metal at high throughout. In addition, lower temperatures may be employed than when using thermal CVD, for example, below 200°C.

[0088] Thermal or plasma-enhanced atomic layer deposition (ALD) may be used in some embodiments. 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, MoFe may be used as a precursor and H2 as a reducing agent. Doses of MoFe and H2 are sequentially introduced into the deposition chamber with a purge gas, such as argon, flowed between.

[0089] In some embodiments, a dose of MoFe may include a small amount of H2 to suppress etching. The concentration of MoFe in the MoFe dose is as described above, i.e., 0.01% or less, 0.008% or less, 0.005% or less, or 0.004% or less of the total gas flowed into the chamber. The balance is wholly or predominately argon or other inert gas. In some embodiments, for example, between 0.5% and 10% or between 1% and 9% is H2, with the balance argon. During the H2 dose, the dose is wholly or predominately H2, with some amount (e.g., up to 10%, or between 1% and 9%) being argon in some embodiments. As above, all % refer to molar percentages. For ALD processes, dose and purge times are relatively fast to avoid disassociated halogen species from etching the molybdenum. Using a lower temperature during ALD also helps prevent etching, e.g., 200° to 400°C. PEALD processes may be used, with the same process gas composition ranges described used for the precursor and H2 doses. Plasma is ignited during the H2 dose. PEALD processes may be performed at lower temperatures, e.g., 100° to 400°C, or 100° to 300°C.Selective Deposition

[0090] 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 a second 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 a 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.

[0091] 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. M0CI5 may be reacted with different reactants 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 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 deposition of the molybdenum film on the dielectric surface may be used to create a barrierless molybdenum layer in the feature.

[0092] In some embodiments, selective deposition is performed using a MoFxprecursor. Molybdenum fluoride precursors are given by the formula MoFxas described above. As indicated above, MoFe can be advantageous for ease of delivery. Deposition of molybdenumfrom MoFe at the low concentrations disclosed above results in high (at least 100:1) selectivity of one elemental metal surfaces (e.g., W, Mo, Cu) relative to oxides and nitrides such as silicon oxide and titanium nitride. This is shown in Figure 6, which shows thickness of Mo after a MoFe / Fh deposition process with MoFe at 0.004% molar concentration on various surfaces. It also shows that selective deposition of Mo on silicon oxide with respect to titanium nitride may be performed at long enough exposure times.

[0093] 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.

[0094] In some embodiments, selective deposition may be performed according to a process as described with respect to Figure 7. In Figure 7, a process begins with providing a substrate having different surface types, e.g., a dielectric surface and a conductive surface in an operation 701. An optional pretreatment may be performed in an operation 703. The pretreatment can be exposure to a metal halide as described above with reference to Figure 5, or a plasma or thermal exposure to a reducing agent such as hydrogen.

[0095] Next, a Mo-containing sublayer is deposited in an operation 705. This can involve a CVD or ALD process as described above. For selective deposition, generally this a thermal, non-plasma process, though there may be some instances in which a plasma-enhanced process is used. Plasma-enhanced processes may have lower selectivity than thermal processes, but higher throughput and the ability to be performed at lower temperatures. The substrate is then exposed to an oxidant in operation 707. This has the effect of resetting the surface and enhancing the selectivity. For example, referring to Figure 6, selectivity of deposition on a metal surface versus an oxide surface is high after 100 Angstroms of Mo deposited, but then begins to decrease. Exposing the substrate to an oxidant can reset the surface to prevent the selectivity decrease. In alternate embodiments, the oxidant in operation 707 can be replaced with another surface reset agent depending on the composition of the surfaces on the substrate, with examples including nitriding agents. Examples of oxidants include thermal oxygen (O2), O2 plasmas, and ozone. Deposition is then performed again in an operation 709, with another sublayer deposited. The same or different process type may be performed in operation 709 as in operation 705. These operations (oxidant and subsequent selective deposition) may be optionally repeated one or more times in an operation 711 before completing deposition of the Mo-containing layer in an operation 713.Non-selective Deposition

[0096] The selectivity described above may be reduced or eliminated using plasma deposition in some embodiments, such that the molybdenum is conformally deposited on dissimilar materials. This may be referred to as non-selective or conformal deposition. In some embodiments, a plasma-based process is used for conformal deposition. Examples of plasma processes include plasma-enhanced ALD (PEALD) or plasma enhanced CVD (PECVD) processes using a molybdenum halide precursor. In some embodiments, the molybdenum halide precursor is M0CI5 or MoFe. A molybdenum oxyhalide may also be used, with examples including MOO2CI2 or MoOCU. Hydrogen (H2) or other reducing agent may be used for the PEALD or PECVD deposition.

[0097] For PECVD deposition, the molybdenum precursor can be co-flowed with the reducing agent. For MoFe, the concentration of the MoFe is as described above, with the mixture flowed into a plasma generator. Remote or direct plasmas may be used. In some embodiments, a capacitively-coupled direct plasma that is generated in the chamber is employed.

[0098] In some embodiments, a process as shown in Figure 8 may be used to reduce selectivity. In Figure 8, a substrate is provided that includes different surface types in an operation 801. An optional surface treatment can then be performed in an operation 803. Operations 801 and 803 may be performed as described above with reference to Figure 7. Next, an ALD process is performed to deposit a Mo-containing nucleation layer in an operation 805. For nucleation layer deposition, a stronger reducing agent than hydrogen is employed. This can allow the film to grow on surfaces that face nucleation delay with hydrogen as reducing agent. As described further below, such a reducing agent can be a silicon-containing or boron-containing reducing agent such as silane (SiH4) or diborane (B2H6). Germanium-containing reducing agents (e.g., GeH4) may be used. These may be used to deposit an elemental molybdenum film. In other embodiments, a reducing agent such as ammonia (NH3) may be used. In such cases, the molybdenum layer may be a molybdenum nitride or molybdenum oxynitride layer, depending on the presence of oxygen in the molybdenum precursor. This oxynitride layer or nitride layer may be converted into an elemental molybdenum layer in the subsequent process.

[0099] When using MoFe, the concentration of MoFe in the MoFe dose may as described above, i.e., 0.01% or less, 0.008% or less, 0.005% or less, or 0.004% or less of the total gas flowed into the chamber. Alternatively, because a stronger reducing agent than hydrogen is used in the subsequent operation, a higher concentration (e.g., up to 0.1% molar) may be used during the MoFe. Some amount of a reducing agent may be present to suppress etching. As described above, this can be between 0.5% and 10% or between 1% and 9% H2. Anotherreducing agent may be included instead of or in addition to hydrogen. The balance is wholly or predominately argon or other inert gas. During the reducing agent dose, the dose is wholly or predominately the reducing agent, with some amount (e.g., up to 10%, or between 1% and 9%) being argon in some embodiments, and the remainder the reducing agent. After deposition of the nucleation layer, a bulk molybdenum layer can be deposited using H2 as a reducing agent by any of the methods described above, including thermal or plasma-enhanced ALD or CVD, in an operation 807. Operations 805 and 807 may take place in the same or different stations when using a multi-station chamber and can be performed at different temperatures.Nucleation Layer

[0100] 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 (CH3)2NB(CH2)2, carboranes such as C2BnHn+2, and other boranes. Examples of boranes include BnHn+4, BnHn+6, 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 (Si2H6).

[0101] In some embodiments, deposition of a Mo nucleation layer may involve using a non- oxy gen-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 layer deposition 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).

[0102] In some embodiments, H2 may be used as a reducing gas for Mo nucleation layer deposition instead of a boron-containing 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 growth, the thickness may be sufficient.

[0103] 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, a B2H6 or a SitU (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.

[0104] 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, AED 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.

[0105] In some embodiments, the reducing agent may be a boron-containing or silicon- containing reducing agent such as B2H6 or SitU. These reducing agents may be used with metal chloride precursors, with metal oxychlorides; however, the B2H6 and SitU may react with water formed as a byproduct during the AED process and form solid B2O3 and SiCk. These are insulating and can remain in the film, increasing resistivity. Use of NH3 also has improved adhesion over B2H6 and SitU 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) facilitate the 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 surfaceenergy 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 film 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

[0106] Etch operations may be used in the methods for filling features with Mo films. Etch operations remove materials such as metals 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 or a MoFxsuch as MoFe. 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).

[0107] A metal halide precursor such as MoClxor MoFxprecursor may be used for both deposition and etch operations. For example, in certain process windows, a M0CI5 or MoFe precursor may concurrently grow a Mo film and etch away a metal or metal compound 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 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.

[0108] In some embodiments, the MoClxprecursor 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 as 700°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.

[0109] In some embodiments, deposition by ALD or CVD may result in deposition at the bottom of the feature and net etch at the top of the feature due to concentration differences within the feature. For example, in Figure 9, an otherwise unfilled feature having a conformal liner layer 912 is shown being exposed to a molybdenum precursor flow. The molybdenum precursor concentration decreases with feature depth, transitioning from an etch regime at the top to a deposition regime at the bottom. For example, for MoFe, concentration at the top may be greater than 0.01% and at the bottom, less than 0.004%. The result is net etch at the field area of the feature and net deposition at the feature bottom. For deep features (e.g., for features having aspect ratios of 10: 1 or higher), the concentration gradient may occur by diffusion limits within the feature. In some embodiments, multiple operations may be performed with different precursor concentrations.

[0110] 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 above. 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.Integration processes including etch and / or inhibition

[0111] Also provided herein are deposition-etch-deposition (DED) techniques and deposition- inhibition-deposition (DID) techniques. These may be used to tailor deposition into features during interconnect metallization and for memory applications.

[0112] Figure 10 shows a feature after a deposition, etch, deposition sequence. A conformal ALD process may be used to deposit Mo into the features. As shown, Mo is deposited conformally around each of the features, evenly from the exterior (slit side) to the interior (nonslit side). This partial fill deposition may be referred to as the Depl operation. Following the deposition, an etch operation may be performed. The etch may etch non-conformally such that the etch removes more of the Mo film on the exterior part of the wordline. In the exterior portion of the wordline, the oxide of the feature may be exposed. The interior portion of thewordline may be etched less such that Mo may remain on the interior features. A second deposition operation may be performed after the etch operation shown. This may be referred to as the Dep2 operation. The deposition may be selective to the Mo film remaining on the film. Thus, the film deposited in the subsequent deposition may be deposited selective to the inner portion of the wordline. As Mo starts to grow, the deposition may become conformal. As shown, after the subsequent deposition, the Mo film may be thicker on the inner portion of the feature compared to the outer portion of the feature.

[0113] In some embodiments, MoFe is used for the Depl partial fill and Dep2 selective deposition. In other embodiments, other molybdenum precursors may be used with the same or different precursor used for Depl and Dep2. Examples of etch chemistries include halogencontaining compounds such as M0CI5, MoOCU, MoFe, F2, NF3, MoFe, BCE, Ch, CIF3, CI2O, SF6, CF4, HF, HBr, and CC14.

[0114] In some embodiments, the etch operation is preceded by an operation to improve etching. In some embodiments, the etch operation is followed by an operation for contamination control. Examples of pre- and post-treatment operations include thermal or plasma-based processes involving exposure to one or more of the following gases or plasmas generated from the following gases NH3, N2, O2, O3, Ar, H2, and halosilanes. Examples of etch processes regimes include pressure ranging from lOOmT to 100T, temperature ranging from room temperature to 750°C, gas flows ranging from 50sccm to 50slm, dose times ranging from 10ms to 60s, and etchant concentrations ranging from 0.001% to 100%.

[0115] In some embodiments, the Depl operation includes deposition of a nucleation layer. The Depl operation may further include deposition of a bulk layer on the nucleation layer. Alternatively, the etch may be performed after the nucleation layer is formed.

[0116] The DED operations described herein may be used for logic applications such as interconnects as well as memory applications. In some embodiments, multiple DED operations are used to fill a feature. The same or different chemistries may be used for each deposition. The molybdenum precursor may be a molybdenum halide or molybdenum oxyhalide as described above or a molybdenum organometallic precursor. The same or different chemistries may be used for each etch operation.

[0117] During the etch, a high flow short dose time may be employed to achieve an anisotropic etch. As indicated above, a pre-treatment may be used to increase etch rate as well as tailor etch profile. For example, etch may be preceded by an anisotropic oxidation or nitridation. This can help etch only in the top of the feature (for vertical features) or outer part of the feature (e.g., outer wordlines in a 3D NAND structure). Examples of oxidation operations includeexposure to O2 or O3 or oxy gen-containing plasmas. Examples of nitridation operations include exposure to NH3 or N2 or nitrogen-containing plasmas. Post-treatments can be used to remove impurities after etch. For example, exposure to a halosilane may be used to remove fluorine or chlorine.

[0118] In some embodiments, a feature fill sequence may include one or more inhibition operations. An inhibition operation is an operation to inhibit nucleation or formation of molybdenum film in a subsequent deposition. It may be used to tune a deposition profile.

[0119] Examples of inhibition chemistries include nitrogen-containing chemistries including NF3, N2, and NH3, and well as halide-containing chemistries such as alkyl halides and B2H6. An inhibitor such as N2 may be co-flowed with a molybdenum precursor and / or H2, for example. The inhibition may be a plasma or thermal operation. If plasma, a remote or direct plasma may be used. Other examples of inhibition operations can include exposure to oxygencontaining, carbon-containing, and phosphorous-containing plasmas.

[0120] De-inhibition operations may be used to reduce the effect of inhibition, either before or after the subsequent deposition. This can be used to further tailor the fill profile. Examples of de-inhibition operations include H2 soak, NH3 soak, and H2 plasma exposure. Soak operations may be continuous flow or pulsed.

[0121] Figure 11 shows examples of DED and DID processes on a vertically-oriented features, e.g., for a logic application. For the DED process, deposited Mo film near the feature top or field region is preferentially etched. This results in a tapered profile. Subsequent deposition is performed without closing off the feature. For the DID process, the field region and the top of the feature are preferentially inhibited, allowing molybdenum to be deposited at the bottom of the feature.

[0122] A process may use various permutations of Depl, Dep2, Etch, Inhibition and deInhibition operations to tailor fill. Examples of process sequences are:Dep - Etch - DepDep - Inhibition - DepDep - Etch(x) - Inhibition(y) - DepDep - Etch(x) - Inhibition(y) - Dep - de-inhibition - DepDep - Inhibition - Etch - DepDep - Etch - Dep - Inhibition - DepDep - Etch - Dep - Inhibition - Dep - de-inhibition - DepDep - Inhibition - Dep - Etch - Dep

[0123] In some embodiments, the dep-etch-dep operations disclosed herein may be integratedinto single chamber metallization processes as described above. In other embodiments, any one or more of the operations may occur in different chambers. These may be connected by vacuum in some embodiments.Apparatus

[0124] Figure 12 depicts a schematic illustration of an embodiment of an ALD process station 1200 having a process chamber 1202 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 13A and 13B depict embodiments of a multi-station processing tool 1300. In some embodiments, one or more hardware parameters of ALD process station 1200, including those discussed in detail below, may be adjusted programmatically by one or more computer controllers 1250. In some other embodiments, a process chamber may be a single station chamber.

[0125] ALD process station 1200 fluidly communicates with reactant delivery system 1201a for delivering process gases to a distribution showerhead 1206. Reactant delivery system 1201a includes a mixing vessel 1204 for blending and / or conditioning process gases, such as a Mo precursor-containing gas, a hydrogen-containing gas, an argon or other carrier gas, or other reactant-containing gas, for delivery to showerhead 1206. One or more mixing vessel inlet valves 1620 may control introduction of process gases to mixing vessel 1204. In various embodiments, deposition of an initial Mo layer is performed in process station 1200 and in some embodiments, other operations such as in-situ clean or Mo gap fill may be performed in the same or another station of the multi-station processing tool 1300 as further described below with respect to Figure 13 A.

[0126] As an example, the embodiment of Figure 12 includes a vaporization point 1203 for vaporizing liquid reactant to be supplied to the mixing vessel 1204. In some embodiments, vaporization point 1203 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 1204. 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 a delay between liquid injection and complete vaporization. Faster vaporization may reduce a length of piping downstream from vaporization point 1203. In one scenario, a liquid injector may be mounted directly to mixing vessel 1204. In another scenario, a liquid injector may be mounted 1directly to showerhead 1206.

[0127] In some embodiments, a liquid flow controller (LFC) upstream of vaporization point 1203 may be provided for controlling a mass flow of liquid for vaporization and delivery to process chamber 1202. 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 a time for dosing a liquid reactant. Thus, in some embodiments, the LFC may be dynamically switched between a feedback control mode and a direct control mode. In some embodiments, this may be performed by disabling a sense tube of the LFC and the PID controller.

[0128] In some embodiments, when using a solid phase precursor, an ampoule 1213 is present for solid precursor delivery. Multiple ampoules may be used for multiple solid precursors. Alternatively, a bulk delivery system for a solid precursor may be used. In certain embodiments, an ampoule may not be present, e.g., when using compounds such as WFe and MOF6.

[0129] Showerhead 1206 distributes process gases toward substrate 1212. In the embodiment shown in Figure 12, the substrate 1212 is located beneath showerhead 1206 and is shown resting on a pedestal 1208. Showerhead 1206 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to substrate 812.

[0130] In some embodiments, pedestal 1208 may be raised or lowered to expose substrate 1212 to a volume between the substrate 1212 and the showerhead 1206. In some embodiments, pedestal 1208 may be temperature controlled via heater 1210. Pedestal 1208 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 850. At the conclusion of a process phase, pedestal 1208 may be lowered during another substrate transfer phase to allow removal of substrate 1212 from pedestal 1208.

[0131] In some embodiments, a position of showerhead 1206 may be adjusted relative to pedestal 1208 to vary a volume between the substrate 1212 and the showerhead 1206. Further, it will be appreciated that a vertical position of pedestal 1208 and / or showerhead 1206 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 1208 may include a rotational axis for rotating an orientation of substrate 1212. It will be appreciated that, in some embodiments, one or more of these exampleadjustments may be performed programmatically by one or more suitable computer controllers 1250. The computer controller 1250 may include any of the features described below with respect to controller 1250 of Figure 12.

[0132] In some embodiments where plasma may be used as discussed above, showerhead 1206 and pedestal 1208 electrically communicate with a radio frequency (RF) power supply 1214 and matching network 1216 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 1214 and matching network 1216 may be operated at any suitable power to form a plasma having a desired composition of radical species. Likewise, RF power supply 1214 may provide RF power of any suitable frequency. In some embodiments, RF power supply 1214 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, frequencies between 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.

[0133] 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.

[0134] In some embodiments, instructions for a controller 1650 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 arecipe 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.

[0135] Further, in some embodiments, pressure control for process station 1200 may be provided by butterfly valve 1218. As shown in the embodiment of Figure 12, butterfly valve 1218 throttles a vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of process station 1200 may also be adjusted by varying a flow rate of one or more gases introduced to the process station 1600.

[0136] Figure 13A and Figure 13B show examples of processing systems. Figure 13A shows an example of a processing system including multiple chambers. The system 1300 includes a transfer module 1303. The transfer module 1303 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 1303 is a multi-station chamber 1309 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.

[0137] Chamber 1309 may include multiple stations 1311, 1313, 1315, and 1317 that may sequentially perform operations in accordance with disclosed embodiments. For example, chamber 1309 may be configured such that station 1311 performs an in-situ treatment using a MoClx precursor. Station 1313 may be configured to selectively treat the field region and upper sidewalls and stations 1315 and 1317 may be configured to perform ALD of bulk Mo using a molybdenum oxyhalide precursor and H2. In another example, chamber 1309 may be configured such that station 1311 performs in-situ clean, station 1313 performs ALD of an initial Mo layer, station 1313 selectively treats the layer, and 1314 deposition of bulk Mo. Inanother example, the chamber 1309 may be configured to do parallel processing of substrates, with each station performing multiple processes sequentially.

[0138] Two or more stations may be included in a multi-station chamber, e.g., 2-6, with the operations appropriately distributed. For example, a two-station chamber may be configured to perform ALD of an initial Mo layer in a first station followed by ALD of bulk Mo in a second station. Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0139] Also mounted on the transfer module 1303 may be one or more single or multi-station modules 1307. In some embodiments, a preclean as described above may be performed in a module 1307, after which the substrate is transferred under vacuum to another module (e.g., another module 1307 or chamber 1309) for ALD. In another example, a module for selective treatment of a film may be mounted on the transfer module. An example is shown in Figure 10.

[0140] The system 1300 also includes one or more wafer source modules 1301, where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 1319 may first remove wafers from the source modules 1301 to loadlocks 1321. A wafer transfer device (generally a robot arm unit) in the transfer module 1303 moves the wafers from loadlocks 1321 to and among the modules mounted on the transfer module 1303.

[0141] In some embodiments, ALD of Mo is performed in a first chamber, which may be part of a system like system 1300, 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. .

[0142] Figure 13B is an embodiment of a system 1300. The system 1300 in Figure 13B has wafer source modules 1301, a transfer module 1303, atmospheric transfer chamber 1319, and loadlocks 1321, as described above with reference to Figure 13 A. The system in Figure 13B has three single station modules 1357a-1375c. The system 1300 may be configured to sequentially perform operations in accordance with disclosed embodiments. For example, the single station modules 1357a-1357c may be configured so that a first module 1357a performs a surface treatment, a second module 1357b performs ALD of an initial Mo layer using a molybdenum halide precursor, and a third module 1357c performs ALD of bulk Mo using a molybdenum oxyhalide precursor. In this example, an in-situ clean may be optionally performed in second module 1357b instead of or in addition to a preclean in first module 1357a. In another example, the single station modules 1357a-1357c may be configured so that a firstmodule 1357a performs a deposition of an initial metal layer, a second module 1357b performs selective treatment, and a third module 1357c performs ALD of bulk Mo using a molybdenum oxyhalide precursor. In yet another example, one module may be configured for deposition, another module for selective treatment, and another module for etch.

[0143] 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 12.

[0144] Returning to Figure 13A and 13B, in various embodiments, a system controller 1329 is employed to control process conditions during deposition. The controller 1329 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.

[0145] The controller 1329 may control all the activities of the apparatus. The system controller 1329 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 1329 may be employed in some embodiments.

[0146] Typically, there will be a user interface associated with the controller 1329. 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 1329. The signals for controlling the process are output on the analog and digital output connections of the deposition apparatus.

[0151] 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.

[0152] In some implementations, a controller 1329 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 1329, 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.

[0153] 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.

[0154] The controller 1329, 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 1329 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. 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.

[0155] 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, andany other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0156] 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.

[0157] The controller 1329 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 instructions 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 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 the substrate. Alternatively, the heater control program may control delivery of a heat transfer gas such as helium to the wafer chuck.

[0158] 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.

[0159] 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 tool; (3) exposing the photoresist to visible or UV or x-ray light with a tool such as a wafer stepper; (4) developing the resist soas 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 comprising: providing a feature to be filled with molybdenum; performing a deposition process to deposit molybdenum in the feature, the deposition process comprising exposing the feature to a process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride, wherein the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.01%.

2. The method of claim 1, wherein the deposition process is a chemical vapor deposition process.

3. The method of claim 1, wherein the deposition process is an atomic layer deposition process further comprising, after exposing the feature to the process gas, exposing the feature to a reducing agent dose comprising hydrogen with no molybdenum hexafluoride.

4. The method of claim 1, wherein the feature comprises a conductive surface and a dielectric surface and further wherein the molybdenum is selectively deposited on the conductive surface.

5. The method of claim 1, further comprising prior to the deposition process, depositing a molybdenum nucleation layer in the feature.

6. The method of claim 5, wherein depositing the molybdenum nucleation layer comprises exposing the feature to sequential doses of a) a nucleation layer process gas comprising molybdenum hexafluoride and b) a non-hydrogen reducing agent.

7. The method of claim 6, wherein the concentration of molybdenum hexafluoride in the nucleation layer process gas is higher than the concentration of molybdenum hexafluoride in the process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride.

8. The method of claim 1, further comprising treating the feature prior to performing the deposition process by exposing it to a metal fluoride.

9. The method of claim 8, wherein the metal fluoride is tungsten hexafluoride or molybdenum hexafluoride.

10. The method of claim 1, wherein the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.004%.

11. A method comprising: providing a feature to be filled with molybdenum; performing a deposition process to deposit molybdenum in the feature, the deposition process comprising exposing the feature to a plasma generated from a process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride, wherein the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.01%.

12. The method of claim 11, wherein the deposition process is a plasma-enhanced chemical vapor deposition process.

13. The method of claim 11, wherein the deposition process is a plasma-enhanced atomic layer deposition process further comprising, after exposing the feature to the process gas, exposing the feature to a hydrogen plasma.

14. The method of claim 11, wherein the feature comprises a conductive surface and a dielectric surface and further wherein the molybdenum is deposited on the conductive surface and the dielectric surface.

15. The method of claim 11, further comprising prior to the deposition process, depositing a molybdenum nucleation layer in the feature.

16. The method of claim 15, wherein depositing the molybdenum nucleation layer comprises exposing the feature to sequential doses of a) a nucleation layer process gas comprising molybdenum hexafluoride and b) a non-hydrogen reducing agent.

17. The method of claim 16, wherein the concentration of molybdenum hexafluoride in the nucleation layer process gas is higher than the concentration of molybdenum hexafluoride in the process gas comprising hydrogen, an inert gas, and molybdenum hexafluoride.

18. The method of claim 11, further comprising treating the feature prior to performing the deposition process by exposing it to a metal fluoride.

19. The method of claim 11, wherein the metal fluoride is tungsten hexafluoride or molybdenum hexafluoride.

20. The method of claim 11, wherein the molybdenum hexafluoride is present in a molar concentration in the process gas of no more than 0.004%.

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