Molybdenum deposition

Abstract

Methods for deposition of molybdenum directly on dielectric surfaces include long reactant doses. Methods of treatment during deposition of a Mo-containing liner layer include exposure to silane.

Description

Attorney Docket No.: LAM1P101WO-12152-1WO MOLYBDENUM DEPOSITIONINCORPORATION BY REFERENCE

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

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

[0002] The background description provided herein is for the purpose of generally presenting the context of disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise quality' as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0003] In some aspects, the techniques described herein relate to a method including: providing a substrate including a structure having a feature to be filled with molybdenum (Mo) to a semiconductor processing tool including one or more chambers; and without depositing a nucleation layer in the feature, performing a first Mo deposition and a second Mo deposition to deposit Mo in the feature, wherein the first Mo deposition deposits Mo directly on a dielectric surface of the feature, wherein the first Mo deposition includes a first atomic layer deposition (ALD) process using a molybdenum precursor and hydrogen (H2), wherein H2 and the molybdenum precursor are provided at a first H2:Mo precursor (partial pressure)»(dose time) ratio,Attorney Docket No.: LAM1P101WO-12152-1WO and wherein the second Mo deposition includes a second ALD process using the molybdenum precursor and H2, wherein H2 and the molybdenum precursor are provided at a second H2:Mo precursor (partial pressure)*(dose time) ratio, and wherein the first H2:Mo precursor (partial pressure)«(dose time) ratio is at least two times greater than the second H2:Mo precursor (partial pressure)*(dose time) ratio.

[0004] In some aspects, the techniques described herein relate to a method, wherein the first HziMo precursor (partial pressure)«(dose time) ratio is at least five times greater than second first H2:Mo precursor (partial pressure)*(dose time) ratio.

[0005] In some aspects, the techniques described herein relate to a method, wherein the first HziMo precursor (partial pressure)*(dose time) ratio is at least ten times greater than the second H2:Mo precursor (partial pressure)*(dose time) ratio.

[0006] In some aspects, the techniques described herein relate to a method, wherein a substrate temperature during the first Mo deposition is at least 550°C and wherein a chamber pressure of a chamber housing the substrate is at least 45 Torr.

[0007] In some aspects, the techniques described herein relate to a method, wherein a substrate temperature during the first Mo deposition is at least 600°C and wherein a chamber pressure of a chamber housing the substrate is at least 45 Torr.

[0008] In some aspects, the techniques described herein relate to a method, wherein the substrate temperature during at least part of the second Mo deposition is at least 100°C lower than during the first Mo deposition.

[0009] In some aspects, the techniques described herein relate to a method, wherein the molybdenum precursor is a molybdenum oxyhalide.

[0010] In some aspects, the techniques described herein relate to a method, wherein the molybdenum precursor is molybdenum dichloride dioxide (MO2CI2O2).

[0011] In some aspects, the techniques described herein relate to a method, wherein the first Mo deposition deposits a layer between 10 and 30 Angstroms thick.

[0012] In some aspects, the techniques described herein relate to a method, wherein the feature is a wordline feature of a 3D NAND structure.Attorney Docket No.: LAM1P101WO-12152-1WO

[0013] In some aspects, the techniques described herein relate to a method, wherein the wordline feature include a first opening and a second opening, the first opening and the second opening being at opposite ends of the feature.

[0014] In some aspects, the techniques described herein relate to a method, wherein the first opening opens to a first vertical structure of the 3D NAND structure and the second opening opens to a second vertical structure and wherein the feature is fluidically accessible via the first and second vertical structures.

[0015] In some aspects, the techniques described herein relate to a method, further including exposing the substrate to ammonia prior to the first Mo deposition.

[0016] In some aspects, the techniques described herein relate to a method, wherein the first ALD process includes multiple doses of H2 separated by a purge and only a single molybdenum precursor dose.

[0017] In some aspects, the techniques described herein relate to a method, wherein the H2 in the first ALD process is delivered from a pressurized vessel.

[0018] In some aspects, the techniques described herein relate to an apparatus including: a multistation chamber, wherein each station includes a substrate support configured to support a substrate and a showerhead configured to inlet gases to a volume above substrate support; and a controller having instructions for: in a first station, performing a first atomic layer deposition (ALD) process using a molybdenum precursor and hydrogen (H2), wherein H2 and the molybdenum precursor are provided at a first H2:Mo precursor (partial pressure)»(dose time) ratio; and at a second station, performing second ALD process using the molybdenum precursor and H2, wherein H2 and the molybdenum precursor are provided at a second H2:Mo precursor (partial pressure) »(dose time) ratio, wherein the first H2:Mo precursor (partial pressure)*(dose time) ratio is at least two times greater than the second IfeMo precursor (partial pressure)»(dose time) ratio.

[0019] In some aspects, the techniques described herein relate to a method including: providing a structure having a feature to be filled with molybdenum (Mo) to a semiconductor processing tool; performing a pre-deposition treatment including exposing the feature to a reducing agent; and performing a first Mo deposition and a second Mo deposition to deposit Mo in the feature, wherein the first Mo deposition deposits Mo directly on a dielectric surface of the feature, wherein the first Mo deposition includes a first atomic layer deposition (ALD) process using a molybdenum precursor and hydrogen (H2), wherein H2 and the molybdenum precursor are provided at a firstAttorney Docket No.: LAM1P101WO-12152-1WO H2:MO precursor (partial pressure)*(dose time) ratio and wherein the second Mo deposition includes a second ALD process using the molybdenum precursor and H2, wherein H2 and the molybdenum precursor are provided at a second H2:Mo precursor (partial pressure)*(dose time) ratio, and wherein the first H2:Mo precursor (partial pressure)*(dose time) ratio is at least two times greater than the second FNMo precursor (partial pressure)»(dose time) ratio.

[0020] In some aspects, the techniques described herein relate to a method, wherein the predeposition treatment includes depositing a discontinuous nitrogen-containing film in the feature.

[0021] In some aspects, the techniques described herein relate to a method, wherein the predeposition treatment includes alternating pulses of ammonia and the molybdenum precursor.

[0022] In some aspects, the techniques described herein relate to a method including: providing a structure having a feature to be filled with molybdenum (Mo) to a semiconductor processing tool; depositing a first portion of a molybdenum-containing liner layer in the feature; exposing the first portion of the molybdenum-containing liner layer to silane to form a silicon-containing molybdenum-containing portion of a liner layer; and depositing a second portion of the molybdenum-containing liner layer on the first portion.

[0023] In some aspects, the techniques described herein relate to a method, wherein the first portion is deposited on a dielectric surface. In some aspects, the techniques described herein relate to a method, further including depositing bulk molybdenum on the second portion.

[0024] These and other aspects are described further below with reference to the Figures.BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1A shows a first material stack featuring a substrate and a molybdenum layer deposited thereon. Figures IB- ID show additional examples of material stacks.

[0026] Figures 1E-1G show an example of depositing molybdenum into a feature having dielectric sidewall surfaces and conductive bottom surface.

[0027] Figures 2A-2L show examples of features that may be filled with molybdenum according to various embodiments.

[0028] Figure 3 shows a flow diagram illustrating certain operations in a method of depositing molybdenum.

[0029] Figures 4A-4D show example of Mo deposition on an incoming dielectric surface.Attorney Docket No.: LAM1P101WO-12152-1WO

[0030] Figure 5 shows examples of timing sequences for operations in the method of Figure 3.

[0031] Figure 6 shows various examples of timing sequences for Mo deposition according to various embodiments.

[0032] Figure 7A shows an example of a single wordline of a 3D NAND structure that includes a first Mo bulk layer deposited directly on a dielectric surface and a second Mo bulk layer that fills the feature.

[0033] Figure 7B shows an example sequence for deposition of molybdenum according to various embodiments.

[0034] Figure 8 is a process diagram show operations in a deposition-etch-deposition (DED) method of filling wordline features of a 3D NAND structure that includes deposition of Mo liner as described above.

[0035] Figure 9 shows a top-down view of pillars of an example of part of a 3D NAND structure.

[0036] Figure 10A depicts a schematic illustration of an embodiment of an ALD process station having a process chamber for maintaining a low-pressure environment.

[0037] Figure 10B depicts an apparatus having gas sources (Mo precursor in carrier gas, Fh, and purge gases) connected to charge vessels.

[0038] Figures 11 A and 11B show examples of processing systems.DETAILED DESCRIPTION

[0039] In the following descriptions, 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 of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0040] Provided herein are methods for deposition of molybdenum (Mo). In some embodiments, molybdenum is deposited directly on a dielectric surface. Deposition of Mo on dielectrics may be implemented without delay by an initial atomic layer deposition (ALD) process that includes a long reactant (e.g.,H2) dose at high temperature and high pressure.Attorney Docket No.: LAM1P101WO-12152-1WO

[0041] Figures 1A-2L show examples of material stacks and structures into which the methods of the disclosure may be used to deposit a Mo liner layer and / or deposit Mo for feature fill.

[0042] Figures 1A and IB are schematic examples of material stacks that include Mo layers according to vanous embodiments. Figures 1 A and IB illustrates the order of materials in examples of particular stacks and may be used with any appropriate architecture application, as described further below wi th respect to Figures 2A-2L. Figure 1 A shows a first material stack 111 featuring a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 may be a silicon or other semiconductor wafer, e.g.. a 200-nm wafer, a 300-nm wafer, or a 450-nm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semi conductive materials 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.

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

[0044] Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, with specific examples including doped or undoped layers of silicon nitride (SiN), silicon dioxide (SiCh), and aluminum oxide (AI2O3). The stack 111 has a layer 106 disposed between the molybdenum layer 108 and the dielectric layer 104. The layer 106 may be a diffusion barrier and / or adhesion layer, for example. A diffusion barrier is a layer that prevents the diffusion of species between layers. An adhesion layer is a layer that promotes adhesion of one layer to an underlying layer. Examples of diffusion barrier and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten (W), tungsten nitride (WN), and tungsten carbon nitride (WCN). In the example of Figure 1A, the molybdenum layer 108 may be the main conductor of the structure. In some embodiments, the molybdenum layer 108 may or may not include a molybdenum nucleation layer. In some embodiments, the molybdenum layer is an amorphous molybdenum-containing layer. In the depicted example of Figure 1 A, the molybdenum layer 108 is deposited directly on the layer 106. In other embodiments (not depicted), the molybdenum layer 108 may be deposited on a separate layer, such as a grow th initiation layer that includes another material, such as a tungsten (W) or W-containing growth initiation layer. The growth initiation layer may be used to facilitate nucleation and growth of molybdenum layer 108.Attorney Docket No.: LAM1P101WO-12152-1WO Still further, in some embodiments, the molybdenum layer 108 may be deposited on a conductive layer that is the main conductor of an underlying structure.

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

[0046] In some embodiments, a stack may include a substrate, a conductive layer, and a molybdenum layer deposited onto the conductive layer. As used herein, a conductive layer or conductive material is a layer or material having a conductivity of at least 104'1-cm'1at 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 stack (not shown), the stack may include a substrate and a molybdenum layer deposited directly on the substrate, including directly on a semiconductor surface, on a dielectric surface, or a conductive surface.

[0047] Figure 1C shows another example of a stack 131. In this example, the stack 131 includes the substrate 102, a conductive layer 103, a molybdenum layer 108, and an overlying conductive layer 103. In some embodiments, molybdenum may be a diffusion barrier layer with another layer deposited thereon. The conductive layers 103 may be the same or different materials. Figure ID shows another layer example of a stack 141. In this example, the stack 141 includes the substrate 102, a dielectric layer 104, molybdenum layer 108, and a conductive layer 103.

[0048] Figures 1 A-1D illustrates examples of the order of materials in a particular stack and may be used with any appropriate architecture and applications. One example of a feature into which molybdenum is deposited according to certain embodiments is shown in Figure IE. In the example of Figure IE, a feature is formed in a dielectric layer 104. The dielectric layer overlies a conductive material 103, such that the feature is defined by dielectric sidewall surfaces 104a and a conductive bottom surface 103a. While the bottom surface 103a and the sidewall surfaces 104a are depicted as being uniform and even horizontal or vertical surfaces in the example of Figure IE, they may be angled, curved, rough, or uneven according to various embodiments.Attorney Docket No.: LAM1P101WO-12152-1WO

[0049] In Figure IF, a conformal Mo layer 108 is shown deposited on both dielectric sidewall surfaces 104a and conductive surface 103a. Thus, the architecture in Figure IF includes Mo on both dielectric and conductive surfaces. In some embodiments, a conductive Mo layer 103 fills the remainder of the feature, as shown in Figure 1G. In the examples of Figures 1E-1G, the Mo layer 108 can be a diffusion barrier layer. The conductive material in each of the conductive layers 103 may be the same or different. In some embodiments, the diffusion barrier is a Mo layer with the conductive layers being tungsten (W) layers. Other examples of materials in conductive layers include metals such as cobalt (Co), ruthenium (Ru), copper (Cu), nickel (Ni), iridium (Ir), rhodium (Rh), tantalum (Ta), and titanium (Ti). Titanium nitride (TiN) may also be used. Other conductive nitrides that may be used in zirconium nitride (ZrN), hafnium nitride (HfN), vanadium nitride (VN), niobium nitride (NbN), tantalum nitride (TaN), as well as MoN and WN. As discussed further below, in some embodiments, the Mo layer at the bottom surface of the feature is etched to reduce resistance between the conductive layers 103.

[0050] Further examples of appropriate architecture and applications for the material stacks shown in Figures 1A-1G are described below' with respect to Figures 2A-2L. The methods described herein are performed on a substrate that may be housed in a chamber. The substrate may be a silicon or other semiconductor wafer, including wafers having one or more layers of materials, such as dielectric, conducting, or semiconducting material deposited thereon. The methods are not limited to semiconductor substrates and may be performed to deposit a molybdenum layer in any feature. Moreover, in some embodiments, the molybdenum compound layer (e.g., molybdenum nitride) may be deposited rather than a molybdenum metal layer (also referred to as an elemental molybdenum layer).

[0051] Examples of features include vias, trenches, and contact holes. Features may be characterized by one or more narrow and / or re-entrant openings, constrictions within the feature, and high aspect ratios. A feature may be formed in one or more of the above-described stacks or layers within a stack. For example, the features may be formed at least partially in a dielectric layer. In some embodiments, a feature may have an aspect ratio of at least about 2: 1, at least about 4: 1. at least about 6: 1, at least about 10: 1, at least about 25: 1, or higher. One example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate.

[0052] Figure 2A depicts a schematic example of a DRAM architecture, including a buried wordline (bWL) 208 in a silicon substrate 202. The bWL 208 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 siliconAttorney Docket No.: LAM1P101WO-12152-1WO substrate 202. In this example, the insulating layer 204 may be a gate oxide layer formed from a high-k dielectric material such as silicon oxide or silicon nitride material. In some embodiments disclosed herein, the conformal barrier layer 206 is TiN or tungsten-containing layer, such as WN or WCN layer. In some embodiments, a conformal tungsten-containing growth initiation layer (not shown) may be present between the conformal barrier layer 206 and the molybdenum bWL 208. Alternatively, the molybdenum bWL 208 may be deposited directly on a TiN or other diffusion barrier. In some embodiments, one or both of layers 204 and 206 is not present. Still further, in some embodiments, the conformal barrier layer 206 is molybdenum or a molybdenum containing layer. The bWL is a conductive material and may be any of the metals described above in some embodiments. The bWL structure shown in Figure 2A is one example of an architecture that includes a conductive fdl 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.

[0053] Figures 2B-2H are additional schematic examples of various structures into which a conductive material may be deposited in accordance with disclosed embodiments. In any of these examples, a Mo liner layer (or a Mo-containing compound liner layer) may be deposited prior to deposition of the main conductive material. In some embodiments, molybdenum is the main conductive material.

[0054] Figure 2B shows an example of a cross-sectional depiction of a vertical feature 201 to be filled with a conductive material. The feature can include a feature hole 205 in a silicon substrate 202. The feature hole 205 may have an underlayer 203 lining the sidewall or interior of the feature hole 205 and may form the interior surfaces. The feature hole 205 or other features may have a dimension near the opening, e.g., an opening diameter or line width of betw een about 10 nm to 500 nm, for example, between about 25 nm to about 300 nm. The feature hole 205 can be referred to as an unfilled feature or simply a feature. The vertical feature 201. and any feature, may be characterized in part by an axis 218 that extends through the length of the feature, with vertically oriented feature having vertical axes and horizontally oriented feature having horizontal axes. The underlayer 203 can be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of underlayers can include dielectric layers and conducting layers. Examples of dielectric materials include oxides, such as SiCh, AI2O3; nitrides, such as SiN; carbides, such as nitrogen-doped silicon carbide (NDC) and oxygen-doped silicon carbide (ODC); and low7k dielectrics, such as carbon doped SiCh. In particular implementations, an underlayer can be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the underlayer is tungsten-free. In some embodiments, the underlayer is molybdenum-free.Attorney Docket No.: LAM1P101WO-12152-1WO

[0055] In some embodiments, features are wordline features in a 3D NAND structure. For example, a substrate may include a wordline structure having an arbitrary number of wordlines (e.g., 50 to 450) with vertical channels at least 200 A deep. Examples of wordline features are described further below. Another example of a feature is a trench in a substrate or layer. Features may be of any depth. In various embodiments, the features may have an underlayer, such as a barrier layer or adhesion layer. Non-limiting examples of underlayers include dielectric layers and conducting layers, e.g., silicon oxides, silicon nitrides, silicon carbides, metal oxides, metal nitrides, metal carbides, and metal layers.

[0056] Figure 2C shows an example of a vertical feature 201 that has a re-entrant profile. A reentrant profile is a profile that narrows from the bottom, closed end, or interior of the feature to the feature opening. According to various implementations, the profile may narrow gradually and / or include an overhang at the feature opening. Figure 2C shows an example of the latter, with an underlayer 213 lining the sidewall or interior surfaces of the feature hole 205. Similar to Figure 2B, underlayer 213 can be a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of underlayers can include dielectric layers and conducting layers. The underlayer 213 forms an overhang 215 such that the underlayer 13 is thicker near the opening of the vertical feature 201 than inside the vertical feature 201.

[0057] In some implementations, features have one or more constrictions within the feature may¬ be filled. Figure 2D shows examples of views of various filled features having constrictions. Each of the examples (a), (b), and (c) in Figure 2D includes a constriction 209 at a midpoint within the feature. The constriction 209 can be, for example, between about 15 nm - 20 nm wide. Constrictions can cause pinch off during the deposition of molybdenum in the feature using conventional techniques, with deposited metal blocking further deposition past the constriction before that portion of the feature is filled, resulting in voids in the feature. Example (b) further includes an overhang 215 (such as, a liner / barrier overhand) at the feature opening. Such an overhang could also be a potential pinch-off point. Example (c) includes a constriction 212 further away from the field region than the overhang 215 in example (b).

[0058] Horizontal features, such as in 3D memory structures, can also be filled. Figure 2E shows an example of a horizontal feature 250 that includes a constriction 251. For example, horizontal feature 250 may be a wordline in a 3D NAND (also referred to as vertical NAND or VNAND) structure. In some implementations, the constrictions can be due to the presence of pillars in a 3D NAND or other structure. Figure 2F presents a cross-sectional side view of a 3D NAND structureAttorney Docket No.: LAM1P101WO-12152-1WO 210 (formed on a silicon substrate 202) having 3D NAND stack (left 225 and right 226), central vertical structure 230, and the plurality of stacked horizontal wordline features 220 with opening 222 on opposite sidewalls 240 of central vertical structure 230. Note that Figure 2F displays two “stacks'’ of the exhibited 3D NAND structure 210, which together form the “trench-like” central vertical structure 230. However, in certain embodiments, there may be more than two such stacks arranged in sequence and running spatially parallel to one another, the gap between each adjacent pair of s stacks forming a central vertical structure 230, like that explicitly illustrated in Figure 2F. In this embodiment, the horizontal wordline features 220 are 2D memory7wordline features that are fluidically accessible from the central vertical structure 230 through the openings 222. Although not explicitly indicated in the figure, the horizontal wordline feature 220 present in both the 3D NAND stacks 225 and 226 shown in Figure 2F (i.e., the left 3D NAND stack 225 and the right 3D NAND stack 226) are also accessible from the other sides of the stacks (far left and far right, respectively) through similar vertical structures formed by additional 3D NAND stacks (to the far left and far right, but now shown). Each 3D NAND stack 225, 226 contains a stack of wordline features that are fluidically accessible from both sides of the 3D NAND stack through a central vertical structure 230. In the particular example schematically illustrated in Figure 2F, each 3D NAND stack contains 6 pairs of stacked wordlines. How ever, 3D NAND memory7layout may contain any number of vertically stacked pairs of wordlines.

[0059] The wordline features in a 3D NAND stack can be formed by depositing an alternating stack of silicon oxide and silicon nitride lay ers, 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 w ordlines may be vertically stacked in such a 3D NAND structure so long as there is a technique for forming them available, as well as a technique available to successfully accomplish (substantially) void-free fills of the vertical features. Thus, for example, a VNAND stack may include between 2 and 512 horizontal wordline features, between 2 and 256 horizontal wordline features, between 8 and 128 horizontal wordline features, or between 16 and 64 wordline features, and so forth (the listed ranges understood to include either recited endpoint).

[0060] Figure 2G presents a cross-sectional top-down view of the same 3D NAND structure 210 shown in the side view in Figure 2F with the cross-section taken through the horizontal section 260 as indicated by the dashed horizontal line in Figure 2F. The cross-section of Figure 2G illustrates several row s of pillars 255, w hich are shown in Figure 2F to run vertically from the base of the substrate 202 to the top of the 3D NAND structure 210. In some embodiments, the pillars 255 are formed from a poly silicon material and are structurally and functionally significant to the 3D NAND structure 210. In some embodiments, such poly silicon pillars may serve as gateAttorney Docket No.: LAM1P101WO-12152-1WO electrodes for stacked memory cells formed within the pillars. The top-view of Figure 2G illustrates that the pillars 255 form constrictions in the opening 222 to wordline feature 220. Fluidic accessibility of wordline features 220 from the central vertical structure 230 via opening 222 (as indicated by the arrows in Figure 2G) is inhibited by pillars 255. In some embodiments, the size of the horizontal gap between adjacent polysilicon pillars is between about 1 and 20 nm. This reduction in fluidic accessibility increases the difficulty of uniformly filling wordline features 220 with the material. The structure of the wordline features 220 and the challenges of uniformly filling them with molybdenum material due to the presence of pillars 255 is further illustrated in Figures 2H. 21, and 2J.

[0061] Figure 2H exhibits a vertical cut through a 3D NAND structure similar to that shown in figure 2F, but here focused on a single pair of wordline features 220 and additionally schematically illustrating a fill process which resulted in the formation of a void 275 in the filled wordline feature 220. Figure 21 also schematically illustrates void 275, but in this figure illustrated via a horizontal cut through pillars 255, similar to the horizontal cut exhibited in Figure 2G. Figure 2J illustrates the accumulation of molybdenum material around the constriction-forming pillars 255, the accumulation resulting in the pinch-off of opening 222, so that no additional molybdenum material can be deposited in the region of voids 275. Apparent from Figures 2H and 21 is that void-free molybdenum fill relies on migration of sufficient quantities of deposition precursor down through central vertical structure 230, through openings 222, past the constricting pillars 255, and into the furthest reaches of the wordline feature 220, prior to the accumulated deposition of molybdenum around pillars 255 causing a pinch-off of the openings 222 and preventing further precursor migration into wordline features 220. Similarly, Figure 2J exhibits a single wordline feature 220 viewed cross-sectionally from above and illustrates how a generally conformal deposition of molybdenum material begins to pinch-off the interior of wordline feature 220 due to the fact that the significant width of pillars 255 acts to particularly block, and / or narrow, and / or constrict what would otherwise be an open path through wordline feature 220. (It should be noted that the example in Figure 2J can be understood as a 2D rendering of the 3D features of the structure of the pillar constrictions shown in Figure 21, thus illustrating constrictions that would be seen in plan view rather than in a cross-sectional view.)

[0062] 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 the precursors diffuse to other parts of the structure.Attorney Docket No.: LAM1P101WO-12152-1WO

[0063] Figures 2K and 2L show examples of asymmetric trench structure DRAM bWL. Some fill processes for DRAM bWL trenches can distort the trenches such that the final trench width and resistance Rs are significantly non-uniform. Figure 2K shows an unfilled feature 261 and filled feature 265 that exhibits the line bending after fill. In this example, the features are a narrow asymmetric trench structure DRAM bWL. As shown, multiple features 283 are depicted on a substrate. These features 283 are spaced apart, and in some embodiments, adjacent features have a pitch between about 20 nm and about 60 nm or between about 20 nm and 40 nm. The pitch is defined as the distance between the middle axis of one feature to the middle axis of an adjacent feature. The unfilled feature 261 may be generally V-shaped, as shown in feature 283, 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. The phenomenon is illustrated in Figure 2L and may be characterized as '"zipping up” the feature. As feature 283 is filled, more force is exerted from the center axis 299 of feature 283, causing line bending. For example, molybdenum may be deposited on the sidewalls of the feature 283. Deposited molybdenum 284a and 284b on sidewalls of feature 283 thereby interact in close proximity, where molybdenum-molybdenum bond radius r is small, thereby causing cohesive interatomic forces between the smooth growing surfaces of molybdenum and pulling the sidewalls together, thereby causing line bending.

[0064] The methods described herein may be used for Mo feature fill in any of the structures and on any of the materials stacks described above. In some embodiments, they are advantageous for deposition in 3D-NAND structures as described with respect to Figures 2F-2K. Deposition in these structures is challenging for several reasons. First, these structures have dielectric surfaces on which the molybdenum is deposited for wordline fill. Metal nucleation on dielectric surfaces is difficult. Second, the structures have high aspect ratios and complex geometry. Uniform reactant distribution from the bottom to the top of the structure and throughout the wordline features is challenging.

[0065] Figure 3 shows a flow diagram illustrating certain operations in a method of depositing molybdenum. The process begins at an operation 301 with a providing a substrate including a structure having one or more features. An example of a feature is any unfilled feature show n in Figures 1A-2L. In particular embodiments, the feature(s) include a dielectric surface. Examples include a complex 3D NAND structure as shown in Figure 2F, with multiple wordline featuresAttorney Docket No.: LAM1P101WO-12152-1WO 220. At an operation 303, the substrate is optionally exposed to a pretreatment. A pretreatment may remove any moisture and / or other contaminants that may be present in some embodiments.

[0066] Figure 4A shows an example of an incoming dielectric surface, which may be for example, a surface of a wordline feature. Dielectric layer 401 has moisture and / or contaminants 402, which are removed with one or more preclean operations. The clean surface of the dielectric layer 401 is shown in Figure 4B. In some embodiments, a pretreatment may be or include exposure to a reducing agent (e.g., S1H4. B2H6, or NH3) that can react with the molybdenum precursor to help prepare the surface for subsequent deposition. However, in some embodiments, after a pretreatment to remove contaminants, the process proceeds without any such soak operation. Certain pretreatments, including exposure to ammonia, can allow a reduction in H2:Mo ratio in the subsequent bulk deposition as well improve surface morphology' of the deposited film.

[0067] In some embodiments, operation 303 can involve one or a few cycles of alternating pulses of a NH3 (or hydrazine) and a molybdenum precursor separated by purges. For example, between 1 and 4 cycles of a NHs / Ar / Mo precursor / Ar pulse sequence may be performed. In some such embodiments, this has the effect of depositing a molybdenum nitride film of less than 5 Angstroms on the surface. This film may be discontinuous and is not bulk growth. This can be useful in the subsequent deposition.

[0068] Returning to Figure 3, the process continues with a first bulk deposition of Mo in an operation 305. Operation 305 is an atomic layer deposition (ALD) process that reacts hydrogen (H2) wdth a molybdenum-containing precursor, e.g., MOO2CI2, with the hydrogen exposure operation long and / or a high partial pressure. In some embodiments, each hydrogen dose involves multiple H2 pulses separated by argon or other inert gas. For example, a 30 second dose of H2 may¬ be broken up into six 5-second doses, e.g.. 6 x (5 seconds H2 followed by 2s Ar purge).

[0069] In some embodiments, charge volumes are used for delivering the H2. Charge volumes may also be used for the molybdenum precursors and / or purge gas. The use of charge volumes can help with overcoming nucleation delay on a dielectric surface.

[0070] Operation 305 is characterized by relatively high H2:Mo precursor ratio. The H2:Mo precursor ratio may be characterized by Torr-seconds:(H2 partial pressure x H2 dose time) / (Mo precursor partial pressure x Mo precursor dose time)

[0071] In some embodiments, the H2:Mo precursor partial pressure-dose time ratio is at least 100 or 200 during operation 305. It may be at least 100. 200, 250, 300. 350, 400. 450, 500, 550. 600,Attorney Docket No.: LAM1P101WO-12152-1WO 800, 1000, 1200, 1400. 1600. 1800. 2000, 2500, 3000, 3100 or even higher. Substrate temperature during operation 305 may be relatively high, e.g., at least 550°C, 575°C, 600°C, 615°C, or 625°C to achieve deposition. In some embodiments, it may be between 600°C and 650°C. Higher temperatures (e.g., up to 800°C) may be used if thermal budgets allow.

[0072] Temperature, H2:Mo ratio, and pressure may be adjusted to achieve deposition. In the following example, molybdenum was deposited on a silica surface at substrate temperatures ranging from 500°C to 615°C using MOO2CI2. In the table below, the growth (none, marginal growth, or good growth) is reported for various temperatures and feMoChCb (Torr-second) ratios. Chamber pressure was 60 Torr.

[0073] The results above indicate that at lower H2 amounts, higher temperatures may be employed for good growth. At lower temperatures, higher H2 amounts may be employed. Lower temperatures can be useful in some embodiments to achieve lower roughness.

[0074] Pressure may be increased to achieve deposition at lower temperatures and / or lower H2:Mo ratios. For example, at 615°C and 80T, deposition occurs at aH2:Mo ratio of 810. Example chamber pressures range from 5 Torr to 200 Torr, 45 Torr to 200 Torr or 45 Torr to 100 Torr, or 45 Torr to 90 Torr. Hydrogen may be delivered via a charge volume as described further below.

[0075] H2:MO ratios that result in good deposition also depend on the particular surfaces and feature geometries. For example, in a 3D structure, the ratio may be lower as Mo concentration per surface area becomes significantly lower with surface area increases. Pretreatment as described above (e.g., NH3 soak or deposition of very thin non-continuous nitrogen-containingAttorney Docket No.: LAM1P101WO-12152-1WO film) can reduce the ratio for good deposition. Example surfaces on which the Mo film is to be deposited include aluminum oxide, silicon oxide, and titanium nitride.

[0076] In some embodiments, the molybdenum precursor is a molybdenum oxyhalide precursor such as MOO2CI2. Such precursors may be advantageously used in high surface area depositions such as for 3D NAND wordline fill, as their vapor pressure is sufficiently high to allow diffusion through the structure.

[0077] The thickness of the bulk film deposited in operation 305 may be 10-50 Angstroms, e.g., 10-20 Angstroms. In some embodiments, it may be thinner, e.g., less than 10 Angstroms or greater, e.g., 50-100 Angstroms. Figure 4C shows the first bulk Mo layer 406 on the dielectric layer 401. As a relatively thin layer, it may be considered to be a liner layer as described elsewhere herein and can be used to initiate subsequent bulk deposition in operation 307. The high H2:Mo ratio in operation 305 allows reduction of molybdenum oxides (MoOx) that are present. This prevents MoOx formation. If the H2:Mo ratio is too low, oxygen may be incorporated in the liner, the subsequent molybdenum grow th will be rough. This and the presence of oxygen will increase resistivity. Pure and smooth bulk molybdenum can be grown with a short nucleation delay.

[0078] In some embodiments, after operation 305, the process of Figure 3 may end. In such cases, a different material (e.g., tungsten) may be deposited in the feature. However, in many embodiments, a thicker Mo film is deposited. This includes embodiments in which feature is filled with Mo (e.g., Mo wordline fill) and embodiments in which a conformal Mo layer (e.g., a Mo diffusion barrier) is deposited in a feature. In these and other embodiments, an operation 307 is performed to deposit bulk Mo. Substrate temperature during operation 307 may be from 450°C to 650°C in some embodiments, though lower temperatures may be used. In some embodiments, a temperature between 500°C and 600°C is used. The temperature may be the same as or different than that of operation 305. Pressure may be the same or lower than that in operation 305. Chamber pressure may be between 20 Torr and 200 Torr, e.g., 30 Torr to 100 Torr. The H2:Mo ratio is lower than in operation 305, and in some embodiments, may be no more than 75%, 50%, 35%, 25%, 20%, or 10% that of the ratio in operation 305. For example, for a H2:Mo Torr-Second ratio of 800 in operation 305, the H2:Mo ratio in operation 307 may be no more than 200 (25%) in some embodiments. In the same or other embodiments, the H2:Mo ratio in operation 307 may be less than 200, less than 150, less than 120, less than 100, less than 75, or less than 50.

[0079] Figure 5 shows examples of timing sequences for operations 305 and 307. For operation 305, N cycles of a high H2:Mo Torr-second ratio ALD process are performed, followed by Al cycles of a low er H2:Mo Torr-second ratio ALD process in operation 307. In the example of Figure 5,Attorney Docket No.: LAM1P101WO-12152-1WO the H2 dose time per cycle is greater during operation 305 than during operation 307. In the same or other embodiments, the volumetric flow rate of H2 and / or H2:Mo precursor molar ratio may be greater during operation 305 than operation 307. In the same or other embodiments, substrate temperature and / or chamber pressure may be greater during the Mo liner deposition of operation 305 than during the subsequent second bulk deposition in operation 307. Figure 4D shows the Mo film 408 deposited on the dielectric layer 401.

[0080] In some embodiments, pressurized distribution of H2 may be employed. An example apparatus is shown in Figure 10B. in which 3 gas sources (Mo precursor in carrier gas. H2, and purge gases) are connected to charge vessels.

[0081] As indicated above, in some embodiments, a long hydrogen dose may be split up into multiple shorter doses separated by a purge when performing the first Mo bulk deposition of operation 305. Figure 6 shows various examples of timing sequences, with multiple H2 Ar dose / purge cycles and a single Mo precursor dose / purge sequence in each example. According to various embodiments, the single Mo precursor dose / purge may be after the multiple Fb / Ar cycles, after the multiple Fb / Ar cycles, or in between the multiple Fb / Ar cycles.

[0082] Figure 7A shows an example of a single wordline 700 of a 3D NAND structure that includes a first Mo bulk layer 703 deposited directly on a dielectric surface and a second Mo bulk layer 705 that fills the feature.

[0083] In some embodiments, the methods disclosed above are used to deposit molybdenum directly on surfaces such as diffusion barrier or dielectric surfaces without deposition of a molybdenum nucleation layer. Unlike a nucleation layer, which is a thin conformal film that serves to facilitate the subsequent formation of a bulk material thereon, bulk molybdenum is used to carry current. Bulk molybdenum is compositionally distinct from a molybdenum nucleation layer such that there is an interface between the bulk tungsten and nucleation layer. In some cases, nucleation layers have relatively high amorphous and / or beta phase content, while bulk layers have high alpha phase content. Bulk molybdenum also has large grain size and lower resistivity than a nucleation layer. In embodiments of the methods disclosed herein, no interface is observed between the two bulk layers described herein.

[0084] Another aspect of the disclosure relates to a treatment during deposition of a Mo-containing liner layer. The Mo-containing liner layer may be a Mo bulk layer deposited as described above with respect to operation 305 of Figure 3, or another liner layer such as a molybdenum oxynitride, molybdenum nitride, or moly bdenum oxide layer. The treatment may beAttorney Docket No.: LAM1P101WO-12152-1WO advantageous for deposition on dielectric and in particular, silicon oxide or other silicon-containing dielectric surfaces.

[0085] Figure 7B shows an example sequence, labeled ‘“Liner 1”; “SiFL soak”, “Liner2”. and “Bulk.” Liner! and Liner2 together form a liner layer that may be e.g., 5 to 50 Angstroms, 10 to 30 Angstroms, or 10 to 15 Angstroms. Examples of reactants that may be used to deposit the liner layer include:• MOO2CI2 and H2 (e.g., and in operation 305, above)• MOO2CI2 and NH3• MOO2CI2 and H2 / NH3

[0086] The reactants may be the same or different for the “Linerl” and “Liner2” depositions. The relative thicknesses of the Linerl and Liner2 sub-layers may be varied. For example, they may be approximately the same thickness (1:1). In other embodiments, a Linerl :Liner2 thickness ratio may range from 1:10 to 10:1, with examples include 1:2, 1:5, 1:10, 10:1, 5:1, and 2:1. Silane exposure may be performed at any appropriate temperature, including at the liner deposition temperature. Examples include 250°C to 550°C. Example SiEL dose times are 0.5 seconds to 60 seconds, e g., 0.5 seconds to 10 seconds.

[0087] After silane exposure, the Linerl film has incorporated silicon. For example, after ALD deposition using MOO2CI2 and NEL, an amorphous MoOxNy layer is present on the dielectric surface. The treatment converts this to an amorphous MoOxNySizlayer (x, y, and z being non-zero numbers). The presence of silicon in the liner improves the thermal stability of the molybdenum, reducing agglomeration and stress of the subsequently deposited bulk film. The subsequent liner deposition (Liner2) restarts the Mo growth, allowing for good quality bulk deposition.

[0088] Silane exposure after deposition of a portion of a liner layer shows reduction in agglomeration and stress. These benefits were not observed with using a silane pretreatment only.

[0089] Silane exposure between liner layer and bulk deposition does show some improvement over no treatment. However, after bulk deposition, the Mo film shows more roughness and resistance than the inter-liner layer treatment described with respect to Figure 7B.

[0090] In some embodiments, the MoOxNySiz liner layer remains amorphous during the bulk deposition. This is in contrast to ALD bulk deposition on amorphous MoOxNy liners, which canAttorney Docket No.: LAM1P101WO-12152-1WO be converted to crystalline molybdenum nitride or molybdenum layers. The amorphous silicon-containing layer can act as a barrier to diffusion of O and Cl, and other species.

[0091] According to various embodiments, Mo feature fill may additionally include other operations after liner deposition. This includes after liner deposition as described with reference to Figure 7B and Figure 3. In the context of Figure 3, the operations can performed between operations 305 and 307 or during or after operation 307. For example, 3D feature fill may involve one or more inhibition and / or etch operations. Figure 8 is a process diagram show operations in a deposition-etch-deposition (DED) method of filling wordline features of a 3D NAND structure that includes deposition of Mo liner as described above. Figure 9 illustrates certain operations of the process of Figure 8. The method of Figure 8 begins with providing a 3D NAND structure having unfilled wordline features in an operation 801. Examples of such structures are described above with respect to Figures 2F-2J. Figure 9 shows a top-down view of pillars of an example of part of a 3D NAND structure. The outer pillars are adjacent to the slit from which the wordline feature are fluidically accessible. In the depicted example, 3 rows of staggered pillars are shown. According to various embodiments, the number of rows may be, e.g., 20 or more. As described above with reference to Figure 2F, there are slits on either side such that reaching the innermost wordlines of 20 rows of pillars involves diffusion through 10 rows of pillars from a slit. Referring back to Figure 2F, the critical dimension of the central vertical structure 230 may be on the order of hundreds of nanometers, with the depth more than 1 micron. The critical dimension of the wordline features prior to molybdenum deposition may be, e.g., 10-20 nm, or 12-16 nm. As described, it can be challenging to fill such features uniformly and void-free. A substrate that includes the 3D NAND structure may be provided to a semiconductor processing tool. As provided, the pillars may include a dielectric layer, e.g., an AI2O3 layer as shown in Figure 9.

[0092] Returning to Figure 8, the method includes depositing a conformal Mo bulk layer by ALD with a high H2:Mo Torr-second ratio in the wordline features of the 3D NAND structure in an operation 803. This may be done as described above with respect to operation 305 Figure 3, for example. A second bulk film is then deposited on the first bulk film in an operation 804. This operation may be performed as described above with respect to operation 307 of Figure 3, for example.

[0093] An example of the features after deposition of the bulk layers is shown in left panel of Figure 9. As shown. Mo is deposited conformally around each of the features, evenly from the exterior (slit side) to the interior (non-slit side). This partial fill deposition may be referred to as the Depl operation. In some embodiments, the first bulk deposition as described herein is used toAttorney Docket No.: LAM1P101WO-12152-1WO deposit a Mo liner layer of no more than 2 nm. This allows the subsequent ALD process to deposit on the first bulk film to increase the total thickness, e.g., to about 4 to 6 nm. The thicknesses of these layers may be modified depending on the dimensions of the structure. The ALD process in Figure 9 is typically a thermal ALD process. This is because achieving lateral fill throughout the wordline feature is easier with a thermal process. Conformal fill throughout the complex structure is also facilitated by use of a molybdenum oxyhalide precursor such as MoChCh rather than a molybdenum halide such as M0CI5. This is in part because molybdenum halides are stronger etchants. With a large and complex structure, a molybdenum halide may etch at the top of the structure while the precursor diffuses through the structure.

[0094] An optional etch pre-treatment may be performed in an operation 805. The pre-etch treatment makes it easier to etch in the subsequent operation. If performed, the pre-etch treatment may be conformal or non-conformal. In some embodiments, it is non-conformal, being preferentially applied to the outer wordlines relative to the inner wordlines. The pre-etch treatment may be an oxidation or nitridation of the molybdenum. The pre-etch treatment may be a plasma or thermal treatment. In some embodiments, a thermal pre-etch treatment may be easier to control the diffusion into the structure and extent of treatment.

[0095] For oxidation, the structure may be exposed to ozone. And, because relatively high temperatures (e.g., 450° to over 600°C), exposure to oxygen gas (O2) or water vapor may be used. For nitridation, ammonia may be used, or another nitrogen-containing gas or plasma. Operation 805 has top to bottom uniformity. As in operation 803, charge volumes may be used to achieve this.

[0096] After the optional pre-etch treatment, an etch that is preferential to the molybdenum in the outer wordlines is performed in an operation 807. In the exterior portion of the wordline feature the oxide of the feature may be exposed. The interior portion of the wordline may be etched less such that molybdenum may remain on the interior features. This is illustrated in the middle panel of Figure 9, with the molybdenum on the outermost pillars removed, the molybdenum in the second row of pillars mostly removed, and the molybdenum on the third row of pillars intact. In some embodiments, the molybdenum is thinned but not completely removed from any portion of the wordline features.

[0097] The extent of etching may be determined based on how many pillars there are, the geometry of the structure, etc. For example, a first etch may be targeted such that molybdenum is removed from all but the innermost pillars, with a subsequent etch leaving molybdenum on the next innermost row, etc. The pre-etch treatment can be used to tune the etch profile. In addition toAttorney Docket No.: LAM1P101WO-12152-1WO or instead of the pre-etch treatment, concentration of the etchant and / or dose time can be used to control the diffusion into the structure and the extent of etching. Chamber pressure and pedestal temperature are the other parameters that can be varied to tune the etch profile. Chamber pressure is used to control chemical diffusion and temperature is used to control the reactivity of the chemical with the Mo surface.

[0098] Higher concentration (and thus higher partial pressure) of the etchant can be used to reach further into the structure. Similarly, a continuous dose or longer pulsed doses will facilitate diffusion. Lower partial pressures and / or shorter doses of etchant can be used to keep the etchant from extending further into the structure. Charge volumes may be used for top to bottom uniformity. 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%.

[0099] Examples of etch chemistries include halogen-containing compounds such as Mods, F2, NF3, MOF6, BCh, HC1, CI2, CIF3, CI2O, SF6, CF4, HF, HBr, WF6, and CC14. For 3D NAND structures, the etch is a thermal etch to avoid plasma damage. However, aspects of the method described in Figure 8 can be applied for logic applications for which a plasma etch may be used. An optional post-etch treatment may be performed in an operation 809. Such a treatment can be used to remove byproducts that can hinder subsequent etching and / or are unwanted in the device. For example, any of oxygen, chlorine, or boron may be removed. The post-etch treatment can involve a reducing soak (e.g., H2 soak) or exposure to a halosilane, for example, for ligand exchange. Other examples include exposure to argon.

[0100] Returning to Figure 8, a thin film is deposited by ALD in an operation 811. Generally, the same precursor and process ranges as used for the conformal thin film in operation 804 are used. Use of a different precursor or process range may be performed. This may be referred to as the Dep2 operation. In embodiments in which oxide is exposed during the etch on the outer portion of the features, the deposition may be selective to the molybdenum film remaining in the wordline features. Thus, the film deposited in the subsequent deposition may be deposited selective to the inner portion of the wordline feature. As molybdenum starts to grow and a nucleation delay is overcome (if present), the deposition may become conformal. As show n in Figure 9, 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. In embodiments in which there is no nucleation delay, the Mo film may be thicker on the inner portion of the feature compared to the outer portion of the feature of the greater thickness after the etch. The right panel of Figure 9 shows the structure after the Dep2Attorney Docket No.: LAM1P101WO-12152-1WO operation. In some embodiments, a liner described above or other nucleation layer may be part of the Dep2 operation.

[0101] Operations 805-811 may be repeated one or more times to fill more of the structure in an operation 813. The pre-treatment. etch, post-treatment, and deposition operations conditions may varied or the same for any two repetitions. For example, the etch in a subsequent iteration may be tailored to extend less into the structure.

[0102] In some embodiments, MoChCh 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. Inhibition and de-inhibition operations as described above may be incorporated into the integration processes.Molybdenum Deposition

[0103] 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 as described above is used. In methods including surface treatment using a molybdenum halide compound, the same or different compound may be used for deposition.

[0104] In some embodiments, a Mo precursor is a molybdenum chloride (MoClx) compound also referred to as a molybdenum chloride precursor or MoClx precursor. Molybdenum chloride precursors are given by the formula MoClx, where x is 2, 3, 4, 5, or 6, and include molybdenum dichloride (M0CI2), molybdenum trichloride (M0CI3), molybdenum tetrachloride (M0CI4), molybdenum pentachloride (M0CI5), and molybdenum hexachloride (MoCls). In some embodiments, M0CI5 or MoCk are used. While the description chiefly refers to MoClx precursors, in other embodiments, other molybdenum halide precursors may be used. Molybdenum halide precursors are given by the formula MoXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)) and z is 2, 3, 4, 5, or 6. Examples of MoXz precursors include molybdenum fluoride (MoFe). In some embodiments, a non-fluonne-containing MoXz precursor is used to prevent fluorine etch or incorporation. In some embodiments, a non-bromine-containing and / or a non-iodine-containing MoXz precursor is used to prevent etch or bromine or iodine incorporation.

[0105] In some embodiments, the feature may be filled using a molybdenum oxyhalide precursor. Molybdenum oxyhalide precursors are given by the formula MoOyXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and y and z are numbers greater than 0Attorney Docket No.: LAM1P101WO-12152-1WO such that MoOyXz forms a stable compound. Examples of molybdenum oxyhalides include molybdenum dichloride dioxide (MOO2CI2), molybdenum tetrachloride oxide (MoOCh), molybdenum tetrafluoride oxide (M00F4), molybdenum dibromide dioxide (MoChBn), and the molybdenum iodides MoOzI, and MO4O11I. It should be understood that as used herein the term molybdenum oxyhalide precursor may refer to a molybdenum oxyhalide precursor as described above or a molybdenum-containing oxyhalide precursor that includes molybdenum, oxygen, a halide and one or more other elements. In some embodiments, molybdenum oxyhalide or molybdenum-containing oxyhalides may include multiple different halogens (e.g., F and Cl and / or I and / or Br, etc.). A feature may be filled with molybdenum using a MoXxprecursor, MoOyXz precursor, or a combination thereof.

[0106] Amolybdenum precursor may be provided in a carrier gas, e.g., Ar in some embodiments. As an example, MOO2CI2 may be provide as 10%(vol) in a process gas with the balance being argon. Reference to partial pressure of the precursor in this document refer to the precursor only, and not the carrier gas.

[0107] 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 (SiEU), diborane (B2H6), germane (GeFU), ammonia (NEL), and hydrazine (N2H4). Ammonia and hydrazine may be used to deposit molybdenum nitrides or molybdenum oxynitrides.

[0108] 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 H2, nitrogencontaining gas, such as nitrogen (N2) and other gases, such as Ar and NEE. The plasma species may be inert or react with the molybdenum precursor to form a film.

[0109] 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.

[0110] ALD is a surface-mediated deposition technique in which doses of a precursor and a reactant are sequentially introduced into a deposition chamber. One or more cycles of sequential doses of a molybdenum precursor and reactant may be used to deposit Mo. For example, in the deposition of an initial molybdenum layer, M0CI5 may be used as a precursor and Fhas a reducing agent. Doses of M0CI5 and H2 are sequentially introduced into the deposition chamber with a purge gas, such as argon, flowed between. For ALD, the temperature of the substrate and theAttorney Docket No.: LAM1P101WO-12152-1WO pressure of the chamber may be controlled. For example, the substrate may be heated between 200°C and 800°C, e.g., between 250°C and 550°C or between 300°C and 500°C between 350°C and 450°C. In some embodiments, the chamber may be pressurized between 10 Torr and 200 Torr, e.g., between 50 Torr and 90 Torr. In some embodiments, the temperature and / or pressure may be used to control the rate of reactions. In some embodiments, the temperature and / or pressure may be used to control selectivity.

[0111] In some embodiments, the Mo precursor is a molybdenum fluoride (MoFx) compound, also referred to as a molybdenum fluoride precursor or MoFxprecursor. Molybdenum fluoride 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 (MoFe).

[0112] MoFs 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.

[0113] Deposition using MoFe with H2 as reducing agent occurs only at unusually low concentration. As an example, for 0.5 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.

[0114] 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 canAttorney Docket No.: LAM1P101WO-12152-1WO reduce or prevent etching with MoFe; however, at low temperatures H2 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 H2 as the reducing agent. For these reasons they may not be appropriate for some applications.

[0115] In some embodiments, molybdenum fill may involve CVD. In a CVD process, the molybdenum precursor and reactant are in vapor phase together in the deposition chamber. Generally speaking, a CVD process fills a feature faster than an ALD process. In one example, the precursor may be a molybdenum oxychloride, such as MOO2CI2, and is flowed into the chamber with a reactant, such as H2. In this example, the wafer is simultaneously exposed to the precursor and reactant, which react and fill features with Mo. In one example, MoFe is flowed into the chamber with a reactant, such as H2. In this example, the wafer is simultaneously exposed to the precursor and reactant, which react and fill features with Mo.

[0116] In still some other embodiments, a feature may be filled using a pulsed CVD process. The pulsed CVD process continuously flows a reactant into a chamber while pulses of a precursor flow into the chamber. For example, H2 gas may be flowed into the chamber and is continuously flowing into the chamber while the molybdenum-containing precursor is intermittently flowing into the chamber. The temperature of the substrate and pressure in the chamber may be controlled during a CVD operation.

[0117] Plasma-enhanced CVD may be used in which a plasma is ignited during the deposition. In a pulsed CVD process, a plasma may be ignited during deposition cycle or during, e.g., pulses of the hydrogen reactant. In some embodiments, a remote plasma may be used. The plasma may be remotely -generated or direct. Further it may be generated by any appropriate plasma generator including a capacitively-coupled plasma generator or an inductively-coupled plasma generator. A microwave plasma generator may be used.

[0118] In addition to the molybdenum halides and molybdenum oxyhalides described herein, the molybdenum films may be deposited using organometallic and / or sulfur-containing precursors. Organometallic molybdenum-containing compounds and / or sulfur-containing molybdenum-containing compounds may be used as molybdenum precursors in some embodiments. Examples of these are given in PCT publication W02023250500, incorporated by reference herein.Selective depositionAttorney Docket No.: LAM1P101WO-12152-1WO

[0119] 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 aTiN 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.

[0120] 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. 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.

[0121] Different precursor gases may have different process windows in which molybdenum film may be selectively deposited. Generally speaking, MoCls gas has a large process window, i.e., large temperature and pressure range, where the precursor gas retains its selectivity. For example, MoCls 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. MoCls deposits selectively on metals, titanium nitride (TiN) and other conductive materials relative to dielectric materials at a wide range of temperatures.

[0122] M0CI5 may react with a different reactant to deposit a molybdenum film. Described below are examples of deposition of molybdenum film within a feature using a M0CI5 precursor and different process controls. In a first example, the M0CI5 precursor is reacted with a hydrogen (H2) reactant using the deposition methods described above. In the description herein, the metal precursors are reacted with H2 as a co-reactant (also referred to as a hydrogen reactant or H2 reactant). Other reactants may be used instead of hydrogen including other hydrogen-containing reactants such S1H4. B2H6, NH3, as appropriate. Reactants such as B2H6 and / or SiFU are stronger reducing agents and generally show reduced selectivity. They can also result in higher resistivity. Thus, in some embodiments, using H2 as described herein is advantageous. As noted above, process temperatures for selective deposition of the molybdenum film from MoCls 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, suchAttorney Docket No.: LAM1P101WO-12152-1WO 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 MoCh 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.

[0123] In some embodiments, selective deposition is performed using a MoFx precursor. Molybdenum fluoride precursors are given by the formula MoFxas described above. As indicated above, MoFe can be advantageous for ease of delivery . Deposition of molybdenum from MoFe at the low concentrations disclosed above results in high (at least 100:1) selectivity on elemental metal surfaces (e.g., W, Mo, Cu) relative to oxides and nitrides such as silicon oxide and titanium nitride. MoFr, also deposits selectively on metals with respect to dielectric materials, though it is less selective than M0CI5. As can be seen, after a delay, MoFe deposits on thermal oxide. Selectivity of molybdenum halides can also be affected by operating at conditions (e.g., concentration, temperature, etc.) at which the molybdenum halide also etches.

[0124] Selective deposition using a molybdenum oxyhalide precursor is much more difficult than using a molybdenum halide precursor. However, the surface treatments described above significantly improve selectivity of Mo deposition from MOO2CI2. As indicated above, examples of MoOyXz precursors include MOO2CI2, MoOCh, MoOF4, MoChBn, MOO2I, and MO4O11I. The feature may be filled using ALD, plasma enhanced ALD, chemical vapor deposition (CVD), or plasma enhanced CVD. For ALD or CVD, H2 may be the reducing agent. Molybdenum deposits more quickly using a molybdenum oxyhalide precursor than the MoClx precursor used in the surface treatment. For example, a MoOyXz precursor may deposit molybdenum at a deposition rate at least twice as fast as a MoClx precursor for a non-plasma process.Non-selective Deposition

[0125] The selectivity7described above may be reduced or eliminated using plasma deposition in some embodiments, such that the molybdenum is deposited on different materials. This may be referred to as non-selective deposition. When ALD processes are used, the non-selective deposition may be conformal to the contours of surface. The plasma is generally an in-situ or direct plasma for non-selective deposition.Attorney Docket No.: LAM1P101WO-12152-1WO

[0126] 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 MoOCh. Hydrogen (H2) or other reducing agent may be used for the PEALD or PECVD deposition.

[0127] 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.

[0128] Non-selective deposition may also be a thermal process using molybdenum oxyhalides. For example, thermal MOO2CI2 and H2 may be used to deposit a molybdenum layer non-selectively. Temperatures at or above 450°C may be used in for thermal deposition from MOO2CI2 and H2.

[0129] To reduce selectivity, an ALD process may be performed to deposit a Mo-containing nucleation layer. 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 (Si Hr) or diborane (B2H6). Germanium-containing reducing agents (e.g., GeF ) 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.

[0130] 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. Another reducing 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, aAttorney Docket No.: LAM1P101WO-12152-1WO 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.Integration processes including etch and / or inhibition

[0131] Etch operations may be used in the methods for fdling 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 (e.g., a TiN) layer from a feature. In another example, the etch process may be used to reduce the thickness of a liner layer. Etch processes may be performed as part of a pre-treatment process as described elsewhere in the disclosure and / or as part of a deposition-etch-deposition process in which molybdenum is etched.

[0132] An etchant is any compound used to remove a material such as a layer, byproduct or contaminant from a surface. In some embodiments, the etchant is a halogen-containing etchant such as chlorine (CI2), fluorine (F2), bromine (Bn), iodine (I2), hydrogen chloride (HC1), hydrogen fluoride (HF), hydrogen iodide (HI), chlorine trifluoride (CIF3), ferric chloride (FeCh), trifluoromethane (CHF3). fluoromethane (CH3F). octafluorocyclobutane (C4Fs), hexafluorobutadiene (C4F6), hexafluorocyclopentadi ene (CsFe), carbon tetrafluoride (CF4), carbon tetrafluoride (CCI4), nitrogen trifluoride (NF3), boron trichloride (BCls), boron trifluoride (BF3), hydrogen bromide (HBr), sulfur tetrafluoride (SF4), sulfur hexafluoride (SFe), thionyl chloride (SOCI2), phosphorus pentafluoride (PFs), phosphorus trifluoride (PF3), silicon tetrabromide (SiBn), or a combination thereof. In some embodiments, a single etchant may be sufficiently effective. In some embodiments a combination including more than one etchant may be utilized. Examples of combinations include oxygen (O2) with one of the above halogen-containing etchants such as chlorine and oxygen; or fluorine and oxy gen. Alternatively, carbon dioxide (CO2) may be combined with one of the above halogen-containing etchants. If a combination of etchants is utilized, they may be flowed through delivery lines together (concomitantly), or sequentially (one following the other). The etchant may be co-flowed with an inert gas, such as argon. In some embodiments, etchants are combined. For example, the halogen-containing etchant may be coflowed with a non-halogen containing etchant.

[0133] In some embodiments, the etchant is M0CI5, MoFe, WFe, WCI5, or any of the other metal halides described above. For example, an 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 MoClx such as M0CI5. In some embodiments, the soak may be done continuously with the Mo halide gas. In some embodiments, the soak may be pulsed, cycling the Mo halide with a purge gas, such as argon (Ar).Attorney Docket No.: LAM1P101WO-12152-1WO

[0134] A molybdenum halide precursor may be used for both deposition and etch operations. For example, in certain process windows, a M0CI5 precursor may concurrently grow a Mo film and etch away a 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. M0CI5 and H2 may be used in a deposition operation when the process temperature is above 550°C.

[0135] In some embodiments, the MoClx precursor at high temperatures, e.g., above 550°C, may continue to etch material at a faster rate than depositing material. For example, M0CI5 may be used to etch a feature by a soak without a reactant. In this example, the temperature may be as high 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.

[0136] 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 MoClx precursor. In some embodiments, the soak may be done continuously. In some embodiments, the soak may be pulsed, cycling MoClx and 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 MoClx compounds 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.

[0137] An etch may be thermal or plasma-enhanced. In some embodiments in which material in lateral features is etched, a thermal etch to allow the etchant chemistry to diffuse into the feature.Attorney Docket No.: LAM1P101WO-12152-1WO

[0138] Inhibition operations may be used in the methods for filling features with Mo films. Inhibition operations inhibit molybdenum nucleation on a surface. As an example, an inhibition operation may be used to inhibit nucleation on only part of a feature, extending from the feature opening to some depth within the feature. In some embodiments, an incoming structure may be treated to inhibit molybdenum nucleation. For example, a feature having dielectric sidewalls and a conductive bottom surface may be treated such that nucleation is inhibited on the upper portion of the sidewalls, facilitating selective deposition. The inhibition treatment may be repeated during the subsequent deposition to maintain its effectiveness.

[0139] A dielectric material may be treated with a halogen-containing chemistry to inhibit molybdenum nucleation. Examples include F2, NFs, BCh, M0CI5, and CI2. Each of these chlorinates or fluorinates oxides inhibiting further nucleation.

[0140] Inhibition operations may also be performed as part of deposition-inhibition-deposition (DID) techniques. In some embodiments, a portion of a molybdenum fdm is treated to inhibit subsequent deposition. Examples of inhibition chemistries include nitrogen-containing chemistries including N2. and NH3. and well as halide-containing chemistries such as alkyl halides. 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 plasmas may be used. Other examples of inhibition operations can include exposure to oxygen-containing, carbon-containing, and phosphorous-containing thermal or plasma chemistries. In some embodiments in which material in lateral features is etched, a thermal inhibition allows the inhibition chemistry to diffuse into the feature.

[0141] Alkyl halides may be used to inhibit nucleation on molybdenum-containing surfaces for DID operations as well as to modify other surfaces including metal nitrides such as TiN. In some embodiments, the halogen-containing compound is an alkyl halide (e.g., a tertiary alky l halide, such as t-butyl chloride or t-butyl iodide). In some embodiments, the halogen-containing compound is an iodine-containing compound. Further examples of inhibitors include trimethylsilylchloride [(CH3)3SiCl] and trimethylsilyl-dimethylamide [(CH3)3SiN(CH3)2. Chlorine (CI2) is an etchant and can also inhibit growth on molybdenum. Inhibition is observed at substrate temperatures of about 450°C to 600°C for non-plasma exposure to CI2.

[0142] 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 deinhibition operations include H2 soak, NH3 soak, and H2 plasma exposure. Soak operations may be continuous flow or pulsed.Attorney Docket No.: LAM1P101WO-12152-1WO

[0143] Also provided herein are deposition-etch-deposition (DED) techniques and depositioninhibition-deposition (DID). These may be used to tailor deposition into features during interconnect metallization and for memory applications. The DED operations described herein may be used for logic applications such as interconnects as well as memory' applications. Filling a 3D NAND structure using a DED technique may also be performed. 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.

[0144] 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 include exposure to O2 or O3 or oxygen-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. Exposure to H2 can be used to remove impurities. According to various embodiments, a post-treatment may be performed after every dose of the etchant or less frequently, for example, at the end of multiple cycles that include etching.

[0145] In some embodiments, the DED sequences 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. Examples of inhibition chemistries include nitrogen-containing chemistries including NF3, N2. and NH3, and well as halide-containing chemistries such as alkyl halides, B2H6, and Ch. 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.

[0146] 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 deinhibition operations include H2 soak, NH3 soak, and H2 plasma exposure. Soak operations may be continuous flow or pulsed. Prolonged precursor and / or reactant dose time after an inhibition treatment may also be used to reduce or eliminate inhibition effects.Attorney Docket No.: LAM1P101WO-12152-1WO

[0147] Aprocess may use various permutations of Depl, Dep2, Etch, Inhibition and de-Inhibition 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 - DepDep - Oxidation - Etch - DepDep - Nitridation - Etch - Dep

[0148] In some embodiments, the dep-etch-dep operations disclosed herein may be integrated into single chamber metallization processes as described above.Apparatus

[0149] Figure 10A depicts a schematic illustration of an embodiment of an ALD process station 1000 having a process chamber 1002 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 11A and 11B (described below) depict embodiments of a system 1100 including a processing tool. In some embodiments, one or more hardware parameters of ALD process station 1000, including those discussed in detail below, may be adjusted programmatically by one or more computer controllers 1050. In some other embodiments, a process chamber may be a single station chamber.

[0150] ALD process station 1000 fluidly communicates with reactant delivery system 1001a for delivering process gases to a distribution showerhead 1006. Reactant delivery7system 1001a includes a mixing vessel 1004 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 1006. One or more mixing vessel inlet valves 1020 may control introduction of process gases to mixing vessel 1004. In various embodiments, deposition of an initial Mo layer is performed in process station 1000 and in some embodiments,Attorney Docket No.: LAM1P101WO-12152-1WO other operations such as a pre-treatment may be performed in the same or another station of the multi-station processing tool of system 1100 as further described below with respect to Figure HA.

[0151] As an example, the embodiment of Figure 10A includes a vaporization point 1003 for vaporizing liquid reactant to be supplied to the mixing vessel 1004. In some embodiments, vaporization point 1003 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 1004. 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 the length of piping downstream from vaporization point 1003. In one scenario, a liquid injector may be mounted directly to mixing vessel 1004. In another scenario, a liquid injector may be mounted directly to showerhead 1006.

[0152] Reactant delivery system 1001a may also include one or more solid precursor delivery components including one or more on-board ampoules 1013 and / or bulk delivery components 1015.

[0153] In some embodiments, a liquid flow controller (LFC) upstream of vaporization point 1003 may be provided for controlling a mass flow of liquid for vaporization and delivery to process chamber 1002. For example, the LFC may include a thermal mass flow meter (MFM) located downstream of the LFC. Aplunger 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.

[0154] Showerhead 1006 distributes process gases toward substrate 1012. In the embodiment shown in Figure 10A, the substrate 1012 is located beneath showerhead 1006 and is shown resting on a pedestal 1008. Showerhead 1006 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to substrate 1012.Attorney Docket No.: LAM1P101WO-12152-1WO

[0155] In some embodiments, pedestal 1008 may be raised or lowered to expose substrate 1012 to a volume between the substrate 1012 and the showerhead 1006. In some embodiments, pedestal 1008 may be temperature controlled via heater 1010. Pedestal 1008 may be set to any suitable temperature, such as between about 200°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 1050. At the conclusion of a process phase, pedestal 1008 may be lowered during another substrate transfer phase to allow removal of substrate 1012 from pedestal 1008.

[0156] In some embodiments, aposition of showerhead 1006 may be adjusted relative to pedestal 1008 to vary a volume between the substrate 1012 and the showerhead 1006. Further, it will be appreciated that a vertical position of pedestal 1008 and / or show erhead 1006 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 1008 may include a rotational axis for rotating an orientation of substrate 1012. It will be appreciated that, in some embodiments, one or more of these example adjustments may be performed programmatically by one or more suitable computer controllers 1050.

[0157] In some embodiments where plasma may be used as discussed above, showerhead 1006 and pedestal 1008 electrically communicate with a radio frequency (RF) power supply 1014 and matching network 1016 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 1014 and matching network 1016 may be operated at any suitable power to form a plasma having a desired composition of ionic and / or radical species. Likewise, RF power supply 1014 may provide RF power of any suitable frequency. In some embodiments, RF power supply 1014 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. In some embodiments, the showerhead is powered and the pedestal is grounded. In some embodiments, the pedestal is powered.

[0158] 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, currentAttorney Docket No.: LAM1P101WO-12152-1WO 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.

[0159] In some embodiments, instructions for a controller 1050 may be provided via input / output control (IOC) sequencing instructions. In one example, the instructions for setting conditions for a process phase may be included in a corresponding recipe phase of a process recipe. In some cases, process recipe phases may be sequentially arranged, so that all instructions for a process phase are executed concurrently with that process phase. In some embodiments, instructions for setting one or more reactor parameters may be included in a recipe phase. For example, a first recipe phase may include instructions for setting a flow rate of e.g., EE 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 the 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 reactant gas (e.g., MOO2CI2) 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.

[0160] Further, in some embodiments, pressure control for process station 1000 may be provided by butterfly valve 1018. As shown in the embodiment of Figure 10A, butterfly valve 1018 throttles a vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of process station 1000 may also be adjusted by varying a flow rate of one or more gases introduced to the process station 1000.

[0161] Figures 11A and 11B show7examples of processing systems. Figure 11 A shows an example of a processing system including multiple chambers. The system 1100 includes a transfer module 1103. The transfer module 1103 provides a clean, vacuum environment to minimize risk of contamination of substrates being processed as they are moved between various modules.Attorney Docket No.: LAM1P101WO-12152-1WO Mounted on the transfer module 1103 is a multi-station chamber 1109 capable of performing ALD processes described above.

[0162] Also mounted on the transfer module 1103 are one or more single station modules 1107a and 1107b. In some embodiments, an optional preclean is performed in a module 1107a with formation of a boron-based layer formed in a module 1107b. Bulk deposition of molybdenum may be performed in chamber 1109. In some embodiments, multiple stations 1111, 1113, 1115, and 1117 that may sequentially perform operations in accordance with disclosed embodiments. For example, chamber 1109 may be configured such that station 1111 perform ALD of a first bulk layer using a molybdenum oxyhalide precursor and H2. Stations 1113, 1115, and 1117 may be configured to perform 1 / 3 deposition of the remaining Mo (e.g., operation 307 of Figure 3). In another example, deposition of the first Mo bulk layer is performed in module 1107b with deposition of the second layer performed in the multi-station chamber 1109. The multi-station chamber 1109 may also be operated in static mode such that the same deposition occurs in parallel on different substrates. In another example, operations 303-307 of Figure 3 are all performed in multi-station chamber 1109. In some embodiments, a single station may perform both high H2:Mo ratio and low H2:Mo ALD. For example, station 1113 may be configured to perform an initial set of ALD cycles using a higher flow of H2. followed by a second set of ALD cycles at a lower H2 flow rate. ALD of the Mo bulk layer at the lower rate may be continued in station 1115 and / or 1117.

[0163] 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 bulk layer in a first station followed by ALD of a second layer of bulk metal in a second station. Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0164] Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0165] The system 1100 also includes one or more wafer source modules 1101, where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 1119 may first remove wafers from the source modules 1101 to loadlocks 1121. A wafer transfer device (generally a robot arm unit) in the transfer module 1103 moves the wafers from loadlocks 1121 to and among the modules mounted on the transfer module 1103.

[0166] Chamber 1109 may have one or more of the following features:Attorney Docket No.: LAM1P101WO-12152-1WO Individually addressable plasma power generators associated with each station;Individually addressable reactant inputs associated with each station;Multi-plenum showerheads on each station;Dual solid precursor delivery systems.

[0167] Solid precursor delivery systems may include bulk delivery systems and / or on-board ampoules.

[0168] Figure 1 IB is an embodiment of a system 1100. The system 1100 in Figure 1 IB has wafer source modules 1101, a transfer module 1103, atmospheric transfer chamber 1119, and loadlocks 1121, as described above with reference to Figure 11A. The system in Figure 11B has three single station modules 1157a, 1157b, and 1157c. The system 1100 may be configured to sequentially perform operations in accordance with the disclosed embodiments. For example, the single station modules 1157a, 1157b, and 1157c may be configured so that a first module 1157a does a pretreatment and deposits a first bulk layer, a second module 1157b deposits a second bulk layer, and module 1157c performs an etch. In accordance with the embodiments disclosed above, any of the modules in Figures 11 A and 1 IB may be configured to perform etch.

[0169] 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 10A.

[0170] Returning to Figure 11A and 1 IB, in various embodiments, a system controller 1129 is employed to control process conditions during deposition. The controller 1129 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.

[0171] The controller 1129 may control all the activities of the apparatus. The system controller 1129 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 1129 may be employed in some embodiments.

[0172] Typically, there will be a user interface associated with the controller 1129. The user interface may include a display screen, graphical software displays of the apparatus and / or processAttorney Docket No.: LAM1P101WO-12152-1WO conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 1129. The signals for controlling the process are output on the analog and digital output connections of the deposition apparatus.

[0177] 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.

[0178] In some implementations, a controller 1129 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,Attorney Docket No.: LAM1P101WO-12152-1WO 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 1129, 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.

[0179] 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.

[0180] The controller 1129. 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 1129 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.Attorney Docket No.: LAM1P101WO-12152-1WO 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.

[0181] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a PVD chamber or module, a CVD chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0182] 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.

[0183] The controller 1129 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 code for tilt and rotation. A process gas control program may include code for controlling gas composition, flow rates, pulse times, and optionally for flowing gas into the chamber prior to deposition in order to stabilize the pressure in the chamber. A pressure control program may include code for controlling the pressure in the chamber by regulating, e.g., a throttle valve in the exhaust system of the chamber. A heater control program may include code for controlling the current to a heating unit that is used to heat the substrate. Alternatively, the heater control program may control delivery of a heat transfer gas such as helium to the wafer chuck.Attorney Docket No.: LAM1P101WO-12152-1WO

[0184] 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.

[0185] 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 so as to selectively remove resist and thereby pattern it using a tool such as a wet bench; (5) transferring the resist pattern into an underlying film or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

Claims

Attorney Docket No.: LAM1P101WO-12152-1WO CLAIMSWhat is claimed is:

1. A method comprising:providing a substrate comprising a structure having a feature to be fdled with molybdenum (Mo) to a semiconductor processing tool comprising one or more chambers; andwithout depositing a nucleation layer in the feature, performing a first Mo deposition and a second Mo deposition to deposit Mo in the feature, wherein the first Mo deposition deposits Mo directly on a dielectric surface of the feature, wherein the first Mo deposition comprises a first atomic layer deposition (ALD) process using a molybdenum precursor and hydrogen (H2), wherein H2 and the molybdenum precursor are provided at a first H2:Mo precursor (partial pressure)*(dose time) ratio, andwherein the second Mo deposition comprises a second ALD process using the molybdenum precursor and H2, wherein H2 and the molybdenum precursor are provided at a second H2:Mo precursor (partial pressure)*(dose time) ratio, and wherein the first H2:Mo precursor (partial pressure)»(dose time) ratio is at least two times greater than the second PNMo precursor (partial pressure)*(dose time) ratio.

2. The method of claim 1, wherein the first H2:Mo precursor (partial pressure)*(dose time) ratio is at least five times greater than second first H2:Mo precursor (partial pressure)»(dose time) ratio.

3. The method of claim 1, wherein the first ffeMo precursor (partial pressure)»(dose time) ratio is at least ten times greater than the second H2AI0 precursor (partial pressure)*(dose time) ratio.

4. The method of claim 1, wherein a substrate temperature during the first Mo deposition is at least 550°C and wherein a chamber pressure of a chamber housing the substrate is at least 45 Torr.

5. The method of claim 1, wherein a substrate temperature during the first Mo deposition is at least 600°C and wherein a chamber pressure of a chamber housing the substrate is at least 45 Torr.

6. The method of claim 5, wherein the substrate temperature during at least part of the second Mo deposition is at least 100°C low er than during the first Mo deposition.

7. The method of claim 1. wherein the molybdenum precursor is a molybdenum oxyhalide.Attorney Docket No.: LAM1P101WO-12152-1WO 8. The method of claim 1, wherein the molybdenum precursor is molybdenum di chloride dioxide (MO2CI2O2).

9. The method of claim 1, wherein the first Mo deposition deposits a layer between 10 and 30 Angstroms thick.

10. The method of claim 1. wherein the feature is a wordline feature of a 3D NAND structure.

11. The method of claim 10, wherein the wordline feature comprise a first opening and a second opening, the first opening and the second opening being at opposite ends of the feature.

12. The method of claim 11, wherein the first opening opens to a first vertical structure of the 3D NAND structure and the second opening opens to a second vertical structure and wherein the feature is fluidically accessible via the first and second vertical structures.

13. The method of claim 1, further comprising exposing the substrate to ammonia prior to the first Mo deposition.

14. The method of claim 1, wherein the first ALD process comprises multiple doses of H2 separated by a purge and only a single molybdenum precursor dose.

15. The method of claim 1, wherein the H2 in the first ALD process is delivered from a pressurized vessel.

16. An apparatus comprising:a multi-station chamber, wherein each station comprises a substrate support configured to support a substrate and a showerhead configured to inlet gases to a volume above substrate support; anda controller having instructions for:in a first station, performing a first atomic layer deposition (ALD) process using a molybdenum precursor and hydrogen (H2), wherein H2 and the molybdenum precursor are provided at a first PNMo precursor (partial pressure)*(dose time) ratio; and at a second station, performing second ALD process using the molybdenum precursor and H2. wherein H2 and the molybdenum precursor are provided at a second H2:MO precursor (partial pressure) *(dose time) ratio, wherein the first FL: Mo precursor (partial pressure)«(dose time) ratio is at least two times greater than the second H2:Mo precursor (partial pressure)«(dose time) ratio.

17. A method comprising:providing a structure having a feature to be filled with molybdenum (Mo) to a semiconductor processing tool;performing a pre-deposition treatment comprising exposing the feature to a reducing agent; andAttorney Docket No.: LAM1P101WO-12152-1WO performing a first Mo deposition and a second Mo deposition to deposit Mo in the feature, wherein the first Mo deposition deposits Mo directly on a dielectric surface of the feature, whereinthe first Mo deposition comprises a first atomic layer deposition (ALD) process using a molybdenum precursor and hydrogen (H2), wherein H2 and the molybdenum precursor are provided at a first H2:Mo precursor (partial pressure)»(dose time) ratio and wherein the second Mo deposition comprises a second ALD process using the molybdenum precursor and H2, wherein H2 and the molybdenum precursor are provided at a second H2:Mo precursor (partial pressure)»(dose time) ratio, andwherein the first H2:Mo precursor (partial pressure)»(dose time) ratio is at least two times greater than the second H2:Mo precursor (partial pressure)»(dose time) ratio.

18. The method of claim 17, wherein the pre-deposition treatment comprises depositing a discontinuous nitrogen-containing film in the feature.

19. The method of claim 18, wherein the pre-deposition treatment comprises alternating pulses of ammonia and the molybdenum precursor.

20. A method comprising:providing a structure having a feature to be filled with molybdenum (Mo) to a semiconductor processing tool;depositing a first portion of a molybdenum-containing liner layer in the feature; exposing the first portion of the molybdenum-containing liner layer to silane to form a silicon-containing moly bdenum-containing portion of a liner layer; and depositing a second portion of the molybdenum-containing liner layer on the first portion.

21. The method of claim 20, wherein the first portion is deposited on a dielectric surface.

22. The method of claim 20, further comprising depositing bulk molybdenum on the second portion.

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