Molybdenum liner deposition

Abstract

Methods and systems for forming molybdenum liner layers in features involve etching during or after deposition of the liner layer. Integration processes include filling the features with conductive material after forming the liner layer. In some embodiments, the molybdenum liner layers are diffusion barriers.

Description

Attorney Docket No. LAM1P057WO-11961-1WOMOLYBDENUM LINER 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 their entireties 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 qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0003] Methods and systems for forming molybdenum liner layers in features involve etching during or after deposition of the liner layer. Integration processes include filling the features with conductive material after forming the liner layer. In some embodiments, the molybdenum liner layers are diffusion barriers.Attorney Docket No. LAM1P057WO-11961-1WO

[0004] One aspect of the disclosure relates to method comprising: depositing a conformal molybdenum film in a feature on a substrate by an atomic layer deposition (ALD) process, wherein the feature is formed within a layer on the substrate and is surrounded by a field region and includes a bottom surface and sidewall surfaces that extend from the field region to the bottom surface, wherein the ALD process comprises multiple cycles of: a) exposing the substrate to a molybdenum precursor; b) exposing the substrate to a reducing agent; and c) exposing the substrate to an etchant.

[0005] In some embodiments, (c) preferentially etches molybdenum on the field region with respect to molybdenum within the feature. In some embodiments, (b) is a plasma-based operation. In some embodiments, (c) is a plasma-based operation.

[0006] In some embodiments, the reducing agent comprises one or more of hydrogen gas and plasma species generated from hydrogen gas. In some embodiments, the etchant comprises one or more of chlorine gas and plasma species generated from chlorine gas. In some embodiments, the flow rate of the reduced agent is at least twice that of the etchant.

[0007] In some embodiments, (b) and (c) are sequential and non-overlapping. In some embodiments, (b) and (c) are at least partially overlapping. In some embodiments, the method further comprises filling the feature with a conductive material. In some embodiments, the conductive material is selected from tungsten (W), cobalt (Co), ruthenium (Ru), molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), and titanium nitride (TiN).

[0008] In some embodiments, the bottom surface is a conductive material and the sidewall surfaces are dielectric materials. In some embodiments, the etchant is selected from: boron trichloride (BCb), carbon tetrachloride (CCI4), thionyl chloride (SOCh), sulfur hexafluoride (SFe), trifluorochloride (CIF3), nitrogen trifluoride (NF3), phosphorous trifluoride (PF3), molybdenum pentachloride (M0CI5), molybdenum hexafluoride (MoFe), and plasma species generated therefrom.

[0009] Another aspect of the disclosure relates to a method comprising: depositing a conformal molybdenum film in a feature on a substrate by an atomic layer deposition (ALD) process, wherein the feature is formed within a layer on the substrate and is surrounded by a field region and includes a bottom surface and sidewall surfaces that extend from the field region to the bottom; etching the conformal molybdenum film to remove it from the bottom surface, leaving the conformalAttorney Docket No. LAM1P057WO-11961-1WO molybdenum film on sidewall surfaces; and depositing a conductive material to fill the feature, wherein the conductive material contacts the bottom surface.

[0010] In some embodiments, the conductive material is selected from tungsten (W), cobalt (Co), ruthenium (Ru), molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), and titanium nitride (TiN).

[0011] These and other aspects of the disclosure are discussed further below with reference to the drawings.BRIEF DESCRIPTION OF DRAWINGS

[0012] Figures 1A-1D are schematic examples of material stacks that according to various embodiments.

[0013] Figures 1E-1G are schematic illustrations of a molybdenum liner deposition according to certain embodiments.

[0014] Figures 2A-2L are schematic examples of various structures into which molybdenum may be deposited in accordance with disclosed embodiments.

[0015] Figure 3 shows examples of profiles of features into which molybdenum may be deposited according to various embodiments.

[0016] Figure 4 shows an example of a feature including a molybdenum liner layer.

[0017] Figure 5 is a process flow diagram showing operations in a method according to various embodiments.

[0018] Figure 6 provides schematic illustrations of a features during deposition of conformal molybdenum liner layers according to various embodiments.

[0019] Figure 7 illustrates operations in a method of forming a structure including molybdenum diffusion barrier and a conductive interconnect.

[0020] Figure 8 is a process flow diagram showing operations in a method according to various embodiments.

[0021] Figure 9 shows examples of sub-processes that may be performed for single chamber metallization.Attorney Docket No. LAM1P057WO-11961-1WO

[0022] Figure 10 depicts a schematic illustration of an embodiment of an ALD process station.

[0023] Figures 11 A and 11B show examples of semiconductor processing tools.DETAILED DESCRIPTION

[0024] 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.

[0025] Provided herein are methods for deposition of molybdenum (Mo) liner layers in features. The Mo liner layers may be used as barrier layers in some embodiments. The methods involve etching molybdenum. In some embodiments, deposition and etch are performed as part of an atomic layer deposition (ALD) process to form a conformal Mo liner layer. In some embodiments, molybdenum at the bottom of a feature is preferentially etched to improve contact with an underlying layer.

[0026] Figures 1A and IB are schematic examples of material stacks that include Mo layers according to various 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 with respect to Figures 2A-2L. Figure 1A shows a first material stack 111 featuring a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 may be a silicon or other semiconductor wafer, e.g., a 200-nm wafer, a 300-nm wafer, or a 450-nm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semiconductive materials deposited thereon. In some embodiments, the substrate 102 may be or include silicon (Si) or silicon germanium (SiGe). The methods may also be applied to form metallization stack structures on other substrates, such as glass, plastic, and the like.

[0027] 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.

[0028] 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 siliconAttorney Docket No. LAM1P057WO-11961-1WO nitride (SiN), silicon dioxide (SiC>2), 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 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 1 A, 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 growth initiation layer that includes another material, such as a tungsten (W) or W-containing growth initiation layer. The growth initiation layer may be used to facilitate nucleation and growth of molybdenum layer 108. 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.

[0029] 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-resistivity 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.

[0030] 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.Attorney Docket No. LAM1P057WO-11961-1WO

[0031] Figure 1 C 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.

[0032] 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 104a. 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.

[0033] In Figure IF, a conformal Mo layer 108 is shown deposited on both dielectric sidewall surfaces 104a and conductive bottom 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.

[0034] 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 anyAttorney Docket No. LAM1P057WO-11961-1WO 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).

[0035] 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 a bout 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.

[0036] 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 silicon substrate 202. In this example, the insulating layer 204 may be a gate oxide layer formed from a high-k dielectric material such as silicon oxide or silicon nitride material. In some embodiments disclosed herein, the conformal barrier layer 206 is TiN or tungsten-containing layer, such as WN or WCN layer. In some embodiments, a conformal tungsten-containing growth initiation layer (not shown) may be present between the conformal barrier layer 206 and the molybdenum bWL 208. Alternatively, the molybdenum bWL 208 may be deposited directly on a TiN or other diffusion barrier. In some embodiments, one or both of layers 204 and 206 is not present. 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 fill layer. During fabrication of the bWL, molybdenum is deposited into a feature that may be defined by an etched recess in the silicon substrate 202.

[0037] 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.

[0038] 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 substrateAttorney Docket No. LAM1P057WO-11961-1WO 202. The feature hole 205 may have an underlayer 203 lining the sidewall or interior of the feature hole 205 and may form the interior surfaces. The feature hole 205 or other features may have a dimension near the opening, e.g., an opening diameter or line width of between about 10 nm to 500 nm, for example, between about 25 nm to about 300 nm. The feature hole 205 can be referred to as an unfilled feature or simply a feature. The vertical feature 201, and any feature, may be characterized in part by an axis 218 that extends through the length of the feature, with vertically oriented feature having vertical axes and horizontally oriented feature having horizontal axes. The underlayer 203 can be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of underlayers can include dielectric layers and conducting layers. Examples of dielectric materials include oxides, such as SiC>2, AI2O3; nitrides, such as SiN; carbides, such as nitrogen-doped silicon carbide (NDC) and oxygen-doped silicon carbide (ODC); and low k dielectrics, such as carbon doped SiCh. In particular implementations, an underlayer can be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the underlayer is tungsten-free. In some embodiments, the underlayer is molybdenum-free.

[0039] 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.

[0040] 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.Attorney Docket No. LAM1P057WO-11961-1WO

[0041] 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).

[0042] Horizontal features, such as in 3D memory structures, can also be filled. Figure 2E shows an example of a horizontal feature 250 that includes a constriction 251. For example, horizontal feature 250 may be a wordline in a 3D NAND (also referred to as vertical NAND or VNAND) structure. In some implementations, the constrictions can be due to the presence of pillars in a 3D NAND or other structure. Figure 2F presents a cross-sectional side view of a 3D NAND structure 210 (formed on a silicon substrate 202) having 3D NAND stack (left 225 and right 226), central vertical structure 230, and the plurality of stacked horizontal wordline features 220 with opening 222 on opposite sidewalls 240 of central vertical structure 230. Note that Figure 2F displays two “stacks” of the exhibited 3D NAND structure 210, which together form the “trench-like” central vertical structure 230. However, in certain embodiments, there may be more than two such stacks arranged in sequence and running spatially parallel to one another, the gap between each adjacent pair of s stacks forming a central vertical structure 230, like that explicitly illustrated in Figure 2F. In this embodiment, the horizontal wordline features 220 are 2D memory wordline features that are fluidically accessible from the central vertical structure 230 through the openings 222. Although not explicitly indicated in the figure, the horizontal wordline feature 220 present in both the 3D NAND stacks 225 and 226 shown in Figure 2F (i.e., the left 3D NAND stack 225 and the right 3D NAND stack 226) are also accessible from the other sides of the stacks (far left and far right, respectively) through similar vertical structures formed by additional 3D NAND stacks (to the far left and far right, but now shown). Each 3D NAND stack 225, 226 contains a stack of wordline features that are fluidically accessible from both sides of the 3D NAND stack through a central vertical structure 230. Tn the particular example schematically illustrated in Figure 2F, each 3D NAND stack contains 6 pairs of stacked wordlines. However, 3D NAND memory layout may contain any number of vertically stacked pairs of wordlines.Attorney Docket No. LAM1P057WO-11961-1WO

[0043] The wordline features in a 3D NAND stack can be formed by depositing an alternating stack of silicon oxide and silicon nitride layers, and then selectively removing the nitride layers leaving a stack of oxides layers having gaps between them. These gaps are the wordline features. Any number of wordlines 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).

[0044] Figure 2G presents a cross-sectional top-down view of the same 3D NAND structure 210 shown in the side view in Figure 2F with the cross-section taken through the horizontal section 260 as indicated by the dashed horizontal line in Figure 2F. The cross-section of Figure 2G illustrates several rows of pillars 255, which are shown in Figure 2F to run vertically from the base of the substrate 202 to the top of the 3D NAND structure 210. In some embodiments, the pillars 255 are formed from a polysilicon material and are structurally and functionally significant to the 3D NAND structure 210. In some embodiments, such polysilicon pillars may serve as gate electrodes for stacked memory cells formed within the pillars. The top-view of Figure 2G illustrates that the pillars 255 form constrictions in the opening 222 to wordline feature 220. Fluidic accessibility of wordline features 220 from the central vertical structure 230 via opening 222 (as indicated by the arrows in Figure 2G) is inhibited by pillars 255. In some embodiments, the size of the horizontal gap between adjacent polysilicon pillars is between about 1 and 20 nm. This reduction in fluidic accessibility increases the difficulty of uniformly filling wordline features 220 with the material. The structure of the wordline features 220 and the challenges of uniformly filling them with molybdenum material due to the presence of pillars 255 is further illustrated in Figures 2H, 21, and 2J.

[0045] 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 throughAttorney Docket No. LAM1P057WO-11961-1WO 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.)

[0046] Three-dimensional structures may need longer and / or more concentrated exposure to precursors to allow the innermost and bottommost areas to be filled. Three-dimensional structures can be particularly challenging when employing molybdenum halide and / or molybdenum oxyhalide precursors because of their proclivity to etch, with longer and more concentrated exposure allowing for more etch as parts of the structure.

[0047] 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 cohesiveAttorney Docket No. LAM1P057WO-11961-1WO interatomic forces between the smooth growing surfaces of molybdenum and pulling the sidewalls together, thereby causing line bending.

[0048] Figure 3 shows example embodiments of patterned features in which deposition of a Mo liner layer may be performed. A patterned feature may be a via or a trench or other appropriate feature formed as a result of a patterning operation in a dielectric layer. Feature 310 shows an example of a patterned feature having an open profile that expands gradually from the bottom of the feature to the feature opening 314. Feature 320 shows an example of a patterned feature having a re-entrant profile that narrows from the bottom of the feature to the feature opening 314. A reentrant profile may also include an overhang at the feature opening 314. Feature 330 shows a feature with a metal undercut profile. According to various implementations, the profile has the metal-containing surface below the sidewall base 318 of the feature 330. There may be voids between the bottom surface 302 and the sidewall base 318. In each of the above profiles, the bottom surface 302 may be a metal-containing surface, for example a metal or metal nitride surface. There may be oxide 316 formed on the bottom surface 302 of the metal or metal nitride. As described further below, a pre-treatment may be used to remove the oxide, if present. The sidewall surfaces may be dielectric surfaces.

[0049] Referring back to Figure IE and IF, in some embodiments, a feature is provided that has a conductive bottom (e.g., tungsten) surface and dielectric sidewalls (e.g, silicon oxide) surfaces. Deposition of molybdenum in such features can be selective or non-selective to the conductive surface depending on the precursor and process conditions used. Selective and non-selective deposition is described further below. For deposition of a Mo liner layer as shown in Figure IF, non-selective deposition in a feature can involve a plasma deposition and / or use of a molybdenum oxyhalide. However, such conditions can result in depositing preferentially in the field region. This can result in excess film at the feature opening, as illustrated in Figure 4, in which molybdenum liner layer 408 is deposited on conductive surface 403 and on dielectric sidewall surfaces 404 in the feature 405 but with excess film deposited on the field regions 406 that surround the feature 405, imparting a reentrant profile to the feature. In some cases, the excess film can impede reactant diffusion into the feature, resulting in incomplete deposition.

[0050] According to various embodiments, deposition of a Mo liner layer as described herein involves etching to prevent excess film deposited on a field region. Figure 5 is a process flow diagram illustrating example operations in a method according to various embodiments. Figure 5 relates to deposition of a conformal Mo liner layer by atomic layer deposition (ALD). ALD is a surface -mediated deposition technique in which doses of a precursor and a reactant are sequentiallyAttorney Docket No. LAM1P057WO-11961-1WO 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 plasma-enhanced ALD (PEALD), a plasma may be ignited during the reactant dose. In one example, sequential doses of a MOO2Q2 and hydrogen plasma are used to deposit a conformal Mo liner layer. As used herein, the term conformal refers to a layer that generally conforms to the shape of the underlying surface. For features that include multiple surface types, it can involve deposition that is non-selective to the surfaces.

[0051] Deposition of the conformal liner is typically done by an ALD process rather than chemical vapor deposition (CVD) to facilitate conformally depositing the liner on the contours of the feature. PEALD or thermal ALD may be used. If the feature has multiple material types (e.g., as in Figure IE), PEALD with a direct plasma may be used with a molybdenum halide as it will result in conformal, non-selective deposition in the feature rather than selective deposition on the conductive surfaces. Example PEALD processes using M0CI5 may use substrate temperatures of 300°C or more. For molybdenum oxyhalides, either thermal or plasma ALD may be used. For thermal ALD, the temperature is high enough for deposition to occur, e.g., with MOO2Q2 and H2, deposition at 450°C or above may be used. For PEALD with MOO2Q2, a wide range of temperatures may be used. For example, a substrate temperature from 100°C to 600°C may be used. If the feature itself is not selective - i.e., it has a uniform material throughout such as previously formed liner film - and that liner film is to be incorporated into the device, the conformal liner may be formed by any ALD process, thermal or plasma, using any molybdenum halide or oxyhalide precursor capable of deposition. While ALD is generally a surface-mediated process, in some embodiments, the deposition is not strictly self-limiting.

[0052] In Figure 5, operations in a single cycle of an ALD process are illustrated. The process 500 begins with a dose of a Mo-containing precursor in an operation 501. In many embodiments, MOO2CI2 is used, though other molybdenum halides or molybdenum oxyhalides are described further below may be used. The methods described herein are not limited to molybdenum halides and molybdenum halides but can be used with any appropriate Mo-containing precursor including organometallic precursors described below. In some embodiments, operation 501 involves adsorption of the precursor on the surfaces of the substate. Next, a chamber housing the substrate is purged, removing any unadsorbed vapor phase molybdenum precursor in an operation 503. Operation 503 may not be performed in some embodiments. The substrate is then exposed to a dose of reactant to react with the adsorbed Mo-containing precursor in an operation 505. If PEALD is used, the reactant may be a plasma reactant. In many embodiments, operation 505 involves a dose of hydrogen (H2) for thermal ALD or a plasma generated from hydrogen forAttorney Docket No. LAM1P057WO-11961-1WO PEALD. The process also includes a dose of an etchant in operation 507. Operation 507 can be a thermal or plasma-based process. In some embodiments, the etchant is chlorine (Ch) or a plasma generated from Ch. As used herein, the term etchant may refer to a gas that etches and / or that is ionized or otherwise activated in a plasma to form ions or other species that etch. It also may be used to refer to the ions or other species that etch. Additional examples of etchants are provided below. Operations 505 and 507 may be sequential or at least partially concurrent. For example, both Fh and Ch may be flowed into the chamber housing the substrate together. Flow of the etchant into the chamber may be begin after that of the reactant and end before, at the same time, or after that of the reactant. In embodiments in which the doses are sequential, they may or may not be separated by a purge operation. In some embodiments, operation 507 is followed by a purge operation 509.

[0053] In some embodiments, the etchant is significantly larger than the reactant such that the penetration depth into the feature is much less than that of the reactant. As an example, a hydrogen ion can penetrate much deeper into a feature than a bulkier ion such as a chlorine ion. In this manner, there is more etching on the field region and top of the feature than deeper within the feature. There may also be significantly less etchant flowed in operation 507 than reactant flowed in operation 505. For example, a volumetric flow rate of an etchant gas may be 2% to 20% or 2% to 10% of that of the reactant.

[0054] Modifications of the process described in Figure 5 can include exposure to the reactant as the first operation in each cycle, followed by a purge, exposure to the molybdenum-containing compound, exposure to the etchant, and purge. Further modifications can include each cycle forming less than a monolayer. In some embodiments, the ALD process may not be strictly selflimiting. For example, one or both of the purge operations may be omitted or shortened such that some gas-phase reactant remains and reacts in the gas phase. This can increase deposition rate. In many embodiments, the process occurs in a single chamber. However, the process may occur with different operations in different chambers.

[0055] In some embodiments, the process 500 shown in Figure 5 is repeated every cycle until the conformal Mo liner layer is formed. In some embodiments, operation 507 may be omitted for a subset of cycles to tailor deposition. The dose time and / or flow rate of operation 507 may be the same or different from cycle-to-cycle.

[0056] In some embodiments, operations 505 and 507 may be independently plasma or thermal operations. If both are plasma operations and are sequential, the plasma power may be the sameAttorney Docket No. LAM1P057WO-11961-1WO or different. In some embodiments, the plasma power is lower during operation 507 than during operation 505.

[0057] Example thicknesses of a conformal liner are 30 Angstroms to 100 Angstroms, e.g., 40 Angstroms to 80 Angstroms.

[0058] In some embodiments, operation 505 involves a chlorine-containing etchant. Examples of chlorine-containing etchants include molybdenum chlorides (MoClx such as M0CI5), chlorine gas (CI2), boron trichloride (BCI3), boron trifluoride (BF3), boron triiodide (BI3), trifluorochloride (CIF3), thionyl chloride (SOCI2), sulfur hexafluoride (SFe), carbon trifluoride (CF3), carbon tetrachloride (CCI4), and combinations thereof, as well as plasmas thereof. In some embodiments, operation 505 involves exposing a fluorine-containing etchant. Examples of other fluorine- containing etchants include hydrogen fluoride (HF), nitrogen trifluoride (NF3), or a metalcontaining fluoride such as molybdenum hexafluoride (MoFe), and combinations thereof, and plasmas thereof.

[0059] Figure 6 shows a schematic illustration of a process according to certain embodiments. Cross-sectional illustrations 611-613 show conformal liner deposition by ALD without etch and subsequent fill. Cross-sectional illustrations 615-617 show conformal liner deposition by ALD with etch and subsequent fill. At 611, a plasma reduction operation liner deposition using H ions or radicals 630 is shown. This may be an operation such as operation 505 in Figure 5, for example. As can be seen in Figure 6, the H ions or radicals diffuse through the entire feature, depositing on the bottom and sidewalls of the feature, as well on the field region. At 612, the conformal liner layer is shown, with film 635 on the field regions thicker than in the feature interior, on the bottom and sidewalls. As a result, an opening 640 to the feature is narrowed and susceptible to pinch-off with further deposition. This can lead to a void, such as void 645 shown at 613. At 615, H ions or radicals 630 are present to react with adsorbed metal precursor as in 611. However, large Cl ions or radicals 632 are also present to etch some of the deposited film. Due to their size and limited quantity, the etching is primarily on the field region. At 616, the conformal liner layer is shown. Compared to 611, the film 637 on the field region is thinner, and the film on the bottom and sidewalls is thicker. The opening 642 is wider at the top of the feature than opening 640 is, while being shallower. This leads to void-free, seam-free super conformal growth, as shown at 617.

[0060] As described above, operations 505 and 507 in Figure 5 may be independently thermal or plasma operations. If plasma operations are employed, the plasma may be direct (in-situ) or remote. Any appropriate plasma generator may be used, including capacitively-coupled plasmaAttorney Docket No. LAM1P057WO-11961-1WO generators, inductively-coupled plasma generators, microwave plasma generators, and the like. In some embodiments, a method as described with respect to Figures 5 and 6 employs an in-situ, capacitively-coupled plasma generator with a powered showerhead.

[0061] In some embodiments, deposition of molybdenum liner layer can involve selectively etching molybdenum from a feature bottom. Figure 7 shows schematic diagrams illustrating feature fill including a selective etch from the feature bottom. At 710, a feature formed in a dielectric layer 704 is shown. The dielectric layer overlies a conductive material 703, such that the feature is defined by dielectric sidewall surfaces 704a and a conductive bottom surface 704a. At 720, a conformal Mo layer 708 is shown deposited on both dielectric sidewall surfaces 704a and conductive surface 703a. This may be performed as described with respect to Figure 5 in some embodiments, or by any other appropriate method. Next at 730, Mo film at the bottom of the feature is etched, leaving the film on at least the sidewalls of the feature. This reduces resistivity and improves contact of the subsequently deposited conductive material 703 to the underlying layer. In some embodiments, the Mo layer 708 is a diffusion barrier is a Mo layer with the conductive layers 703 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).

[0062] In some embodiments, selectively etching Mo at the bottom of the feature involves a plasma etch with a direct plasma and including powering a pedestal. This allows ion species to be anisotropically directed to the bottom of the feature and to etch the bottom of the feature without etching (or with etching significantly less) from the sidewalls. Material may also be removed the field region. In some embodiments, chlorine (Ch) is used to generate the etching plasma.

[0063] Other examples of chlorine-containing etchants include molybdenum chlorides (MoClxsuch as M0CI5), chlorine gas (CI2), boron trichloride (BCh), boron trifluoride (BF3), boron triiodide (BI3), trifluorochloride (CIF3), thionyl chloride (SOCI2), sulfur hexafluoride (SFe), carbon trifluoride (CF3), carbon tetrachloride (CCI4), and combinations thereof, as well as plasmas thereof. In some embodiments, operation 505 involves exposing a fluorine-containing etchant. Examples of other fluorine-containing etchants include hydrogen fluoride (HF), nitrogen trifluoride (NF3), or a metal-containing fluoride such as molybdenum hexafluoride (MoFe), and combinations thereof, and plasmas thereof.

[0064] In the example of Figure 7, film formation of Mo layer 708 is shown prior to selectively etching the bottom of the feature. In some other embodiments, a method as described with respect to Figure 5 may be performed for one or more cycles of an ALD process to selectively etch at theAttorney Docket No. LAM1P057WO-11961-1WO bottom of the feature with respect to the sidewalls. At 740, the feature is shown filled with conductive material 703.Single Chamber Metallization

[0065] In some embodiments, the methods described herein are implemented as part of a single chamber metallization process. Figure 8 is a process flow diagram illustrating example operations in a method 800 for single chamber metallization that employs an etch as described herein. The process begins with an operation 801 in which a feature having dielectric sidewalls and a metalcontaining contact is provided. The metal-containing contact may be at the bottom of the feature with the dielectric sidewalls extending from the feature opening to the metal-containing contact. The feature may be provided to a processing chamber. In some embodiments, one or more processing operations may occur in the processing chamber to form the feature having dielectric sidewalls and a metal-containing containing contact.

[0066] Examples of dielectric sidewalls include silicon-containing layers such as oxides and nitrides. Examples of metal-containing contacts include metals and metal compound films. The metal -containing contact may be generally conductive, having a conductivity of at least 104 1- cm1at room temperature. Examples include TiN, TiAlC, W, Co, Mo, Ru, Cu, Ni, Rh, Ir, Ta, Ti, TiSix, RuSix, NiPtSix, TiSiN, MoSix, CoSix. and TaN.

[0067] In some embodiments, a surface oxide is present on the metal-containing contact. Still further, in some embodiments, a layer containing other impurities is present on the metalcontaining contact.

[0068] In some embodiments, an etch operation to remove a liner layer from at least the sidewalls of the feature is performed prior to operation 801. For example, a feature may include a TiN liner layer conformally coating the bottom and sidewalls. An etch may be performed to remove the TiN layer from the sidewalls, exposing dielectric material. The sidewall surfaces are then silicon oxide or other dielectric material.

[0069] In an operation 803, a pre-treatment is performed. Operation 803 can remove surface oxide and / or etch residue, for example. Examples of etch residue include fluorocarbons and hydrocarbon polymers. According to various embodiments, operation 803 involves exposure to a metal halide gas (e.g., molybdenum halide gas or a tungsten halide gas) and / or a plasma clean.

[0070] A plasma clean may be remotely generated or generated in-situ. In some embodiments, operation 803 involves exposure to a reducing plasma such as a H2 plasma. In some embodiments,Attorney Docket No. LAM1P057WO-11961-1WO operation 803 treats the dielectric sidewalls. For example, it may remove organic materials and / or reduce oxygen in the dielectric sidewalls.

[0071] In some embodiments, the clean involves exposure to a metal halide gas. For example, the feature may be exposed to a molybdenum halide gas such as M0CI5. This may be a plasma- free operation. Plasma-free refers to the operation performed without activating a plasma. Exposure to a molybdenum halide can remove impurities from the metal contact. In some embodiments, a molybdenum chloride compound is used. Molybdenum-containing compounds are also referred to herein as Mo-containing precursors or Mo precursors. Molybdenum chlorides 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 (MoCE), molybdenum pentachloride (M0CI5), and molybdenum hexachloride (MoCE). In some embodiments, M0CI5 or MoCE are used. While the description chiefly refers to MoClxcompounds, in other embodiments, other molybdenum halides 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. In the case of M0CI5, it can also exists as a dimer, M02Q10 within the ampoule. Examples of MoXzprecursors include molybdenum fluoride (MoFe). In some embodiments, a non-fluorine- containing MoXzprecursor is used to prevent fluorine etch or incorporation. In some embodiments, a non-bromine-containing and / or a non-iodine -containing MoXzprecursor is used to prevent etch or bromine or iodine incorporation.

[0072] In some embodiments, operation 803 involves exposure to the molybdenum halide compound without a co-reactant gas. Tn such embodiments, the molybdenum halide may be pulsed or delivered in a continuous dose. For example, M0CI5 may be pulsed with argon (Ar) other inert gas for a certain number of cycles. Alternatively, a continuous dose of MoCE can be delivered followed by an Ar purge.

[0073] In some embodiments, operation 803 involves exposure to the molybdenum halide compound with a co-reactant gas to deposit Mo. The co-reactant is generally H2, though other reducing agents as described below may be used. In one example sequence, M0CI5 pulses are alternated with H2 pulses with intervening purge gas pulses. In another example, MoCE pulses are alternated with H2 pulses with no intervening purge gas pulses. In another example sequence, M0CI5 pulses are alternated with H2 pulses with a purge gas pulse directly after only one of the reactant gases in each cycle. In another example sequence, MoCE is flowed with H2. In the further example sequence, the co-flowed reactants are pulsed with an alternating Ar pulse. In another example sequence, H2 gas may be flowed into the chamber and is continuously flowing into theAttorney Docket No. LAM1P057WO-11961-1WO chamber while M0CI5 is intermittently flowing into the chamber. In any of these examples, another molybdenum halide and / or another inert gas may be used instead of M0CI5 and Ar, respectively. Also, in any of these examples, the H2 operation may be a plasma operation. In some embodiments, sequences with a co-reactant may be employed when metals besides Mo are at the feature bottom. In such embodiments, a Mo surface layer may be formed facilitating subsequent Mo growth. For example, if a W, Co, or Ru layer is at the feature bottom, operation 603 may be used to form a thin Mo surface layer.

[0074] In addition to or instead of any of the operations described above, operation 603 can involve an atomic layer clean with a chlorine-based plasma, a hydrogen fluoride (HF) vapor clean, an ammonium fluoride (NH4F) clean, or a treatment using other reducing agents. These operations may be used to reduce oxide off a feature surface.

[0075] The process continues at operation 805 with conformal deposition of a Mo layer in the feature. Operation 805 can involve a process as described with respect to Figure 5, for example.

[0076] In some embodiments, this operation involves reaction using a molybdenum halide or a molybdenum oxyhalide precursor. In some embodiments, MOO2CI2 is used as it deposits on dielectric and conductive surfaces in a range of conditions as described below. In some embodiments, a selective deposition of Mo or another metal can be performed prior to operation 805 to deposit a metal fill layer on the conductive bottom of the feature.

[0077] Process conditions such as the precursor gas, the reducing agent, substrate temperature, process pressure, and exposure time may affect the selectivity and non-selectively of the Mo film being deposited. Different precursor gases may have different process windows in which Mo film may be selectively deposited. For example, M0CI5 is selective while MOO2CI2 is not, i.e., under the same temperature and pressure conditions, the precursor gas of M0CI5 may deposit Mo only on a conductive surface and not on a dielectric surface while a precursor gas of MOO2Q2 will deposit Mo on both conductive and dielectric surfaces. Generally speaking, M0CI5 gas has a large process window, i.e., large temperature and pressure range, where the precursor gas retains its selectivity. For example, M0CI5 may be selectively deposited on a metal material with respect to a dielectric material where the process temperature is 300°C to 800°C. In some embodiments, the substrate temperature is 350°C to 550°C. Generally speaking, higher process temperatures and higher process pressures reduce the selectivity of the deposited film. For example, at higher temperatures, a precursor gas such as M0CI5 may lose its selectivity and deposit Mo film on both a metal surface and dielectric surface within a feature.Attorney Docket No. LAM1P057WO-11961-1WO

[0078] In some embodiments, operation 805 can be a thermal or plasma-based process. In some embodiments, operation 805 is a plasma-enhanced ALD (PEALD) using a molybdenum oxyhalide or molybdenum halide precursor. In some embodiments, the molybdenum halide precursor is M0CI5. Hydrogen (H2) or other reducing agent may be used for the PEALD deposition. In some embodiments, operation 805 can be a thermal process.

[0079] The process in Figure 8 may continue with an etch in an operation 807. In some embodiments, the etch in operation 807 can be consider part of operation 805. For example, as described with respect to Figure 5, in some embodiments, an etch may be performed during ALD deposition in operation 805. In some embodiments, an etch may be performed after operation 805. Figure 7 shows an example of sch a process.

[0080] Returning to Figure 8, the process may continue with fill of the feature with conductive material in an operation 809. Operation 809 may include one or more deposition, inhibition, and etch operations as described further below. The sequence of these operations as well as the precursor used can depend on the feature profile. For example, if the feature is re-entrant, one or more etch and / or inhibition operations may be used to tailor the fill. For less challenging structures, such as V-shaped structures, PEALD may be used, for example. These structures may also be filled using a pulsed CVD process in some embodiments. Further description of possible fill techniques of re-entrant features is described below. According to various embodiments, a Mo or a different metal that Mo (e.g., W) may be used to fill the feature.

[0081] Figure 9 shows examples of sub-processes that may be performed for interconnect metallization. In one example of Figure 9, all operations described with reference to Figure 5-8 are performed in a single chamber, which may be a multi-station or single station chamber. Such a chamber may be equipped for delivery of two solid precursors (e.g., M0CI5 and MOO2Q2). In some embodiments, all operations except for final fill may be performed in a single chamber, with final fill performed in a different chamber.

[0082] The example of Figure 9 refers to various inhibition and deposition-etch-deposition (DED) operations. These are described more fully below. In other embodiments, any one or more of the operations may occur in different chambers. These may be connected by vacuum in some embodiments.

[0083] Figure 9 describes single chamber interconnect metallization processes, including pretreatment, selective prefill, conformal liner, etch, and final fill operations. Interconnect metallization may include all of the pre -treatment, selective prefill, conformal liner, etch, and finalAttorney Docket No. LAM1P057WO-11961-1WO fill operations or a subset of these. For example, a single chamber metallization process may include pre -treatment, selective prefill, followed by a deposition that results in complete fill of the feature. See, for example, Figure 9, which shows PECVD using MOO2Q2 as options both the conformal liner and the final fill. A PECVD operation performed after pre-treatment and / or selective fill may be used to fill a feature without forming a conformal liner as part of a separate fill operation. This also may be characterized as deposition of a conformal liner continuing until the feature is filled. Examples of other single chamber fill processes are below. In the examples, below “conformal liner” may or may not include an integrated etch operation as described above.Pre-treatment / conformal liner / etch I final fillPre-treatment / conformal liner / final fillPre-treatment / selective prefill / final fill I etchPre-treatment / selective prefill / etch I confonnal liner I etch / final fillPre-treatment / conformal liner / final fillPre-treatment / conformal liner

[0084] Any one or more of the sub-processes described may be used for each of pre-treatment, selective prefill, confonnal liner, etch, and final fill. Turning to pre-treatment, as described above, the pre-treatment may be a thermal or plasma treatment. An example of a themial treatment is exposure to a metal halide. This can be a molybdenum halide as described above or another metal halide, such as a tungsten halide. Tungsten hexafluoride (WFe) or MoFe may be used in some embodiments. These pretreatment agents are gases at standard pressure and temperature, allowing delivery at room temperature through a mass flow controller. Direct or remote plasma pre-cleans may be used. Exposure to a reducing plasma such as a H2 plasma may be performed. For interconnect metallization, the incoming bottom surface may be a conductive surface. Examples include elemental metal films such as tungsten, molybdenum, copper, cobalt, titanium, ruthenium, or metal-containing conductive compounds films such as titanium nitride and tungsten nitride. Sidewall surfaces are dielectric and include silicon oxides, silicon nitrides, silicon carbides, silicon oxycarbides, silicon oxynitrides, aluminum oxides, and the like. The pre-treatment can be used to remove surface oxides of the conductive surface and / or treat dielectric sidewalls as discussed above.

[0085] Selective pretill, if performed, results in preferential deposition on the conductive surface relative to the dielectric surfaces. In some embodiments, it is performed to reduce the aspect ratioAttorney Docket No. LAM1P057WO-11961-1WO of the feature for subsequent fill. Processes that may be used include thermal deposition using a molybdenum halide, e.g., M0CI5 or MoFe. The thermal deposition may be an atomic layer deposition (ALD), a pulsed chemical vapor deposition process (pulsed CVD), or a continuous flow CVD process. ALD is a surface-mediated deposition technique in which doses of the Mo halide precursor and hydrogen (H2) are sequentially introduced into a deposition chamber, optionally with an argon or other inert gas purge between sequential reactant doses. One or more cycles of sequential doses of the molybdenum precursor and H2 are used to deposit Mo selectively. In continuous flow thermal CVD, the Mo halide and H2 are flowed concurrently to the chamber for a gas phase reaction. Pulsed CVD process sequences can involve continuous flow of one or more process gases and pulsed flow of one or more other process gases.

[0086] Selective deposition on conductive surfaces with respect to dielectric surfaces is an inherent feature using molybdenum halides and hydrogen (H2) for thermal ALD, thermal CVD, and thermal pulsed CVD at appropriate conditions. As described further below, M0CI5 and MoFe have a large process window, i.e., large temperature and pressure range, where the precursor gas retains its selectivity. For example, M0CI5 may be used to selectively deposit molybdenum on a metal or metallic conductive 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 deposition. However, selectivity is significantly controlled by precursor identity with molybdenum halides resulting in much greater selectivity than molybdenum oxyhalides. Selectivity can also decrease with the use of stronger reducing agents than hydrogen. These include silane and diborane, for example. In some embodiments, plasma deposition may be used for selective prefill. In such embodiments, the plasma may be a remote plasma, with hydrogen radicals that are generated in a plasma generator remote to the process chamber fed to the reactor. Description of thermal ALD, thermal CVD, and thermal pulsed CVD herein may be modified with hydrogen radicals flowed to the chamber rather than hydrogen gas for selective deposition.

[0087] As noted above, selective deposition refers to deposition that preferentially occurs on one surface type over another. According to various embodiments, a feature may be provided to the chamber with two material types (e.g., a conductive metal bottom and dielectric sidewalls). In other embodiments, a feature may be provided to the chamber having a single material type that is treated to allow selective deposition. As an example, a feature may be provided with a TiN liner conformally lining the bottom and sidewalls of the feature. It may be exposed to a high temperature molybdenum halide that preferentially etches the TiN layer at top of the surface to form a TiN cup at the feature bottom, exposing dielectric sidewalls at the top of the surface.Attorney Docket No. LAM1P057WO-11961-1WO Molybdenum may then be selectively deposited on the TiN cup. The molybdenum halide exposure may be performed as part of the pre-treatment process described above. In another example, a feature having uniform surface materials may be treated by inhibiting deposition on a portion of the feature. For example, an inhibition treatment may be performed to inhibit deposition at the feature opening.

[0088] Deposition of the conformal liner is typically done by an ALD process rather than CVD to facilitate conformally depositing the liner on the contours of the feature. PEALD or thermal ALD may be used. If the feature has multiple material types (e.g., as in Figure IE), PEALD with a direct plasma may be used with a molybdenum halide as it will result in conformal, non-selective deposition rather than selective deposition on the conductive surfaces. Example PEALD processes using M0CI5 may use substrate temperatures of 300°C or more. For molybdenum oxyhalides, either thermal or plasma ALD may be used. For thermal ALD, the temperature is high enough for deposition to occur, e.g., with MOO2Q2 and H2, deposition at 450°C or above may be used. For PEALD with M0O2O2, a wide range of temperatures may be used. For example, a substrate temperature from 100°C to 600°C may be used.

[0089] If the feature itself is not selective - i.e., it has a uniform material throughout such as previously formed liner film - and that liner film is to be incorporated into the device, the conformal liner may be formed by any ALD process, thermal or plasma, using any molybdenum halide or oxyhalide precursor capable of deposition.

[0090] Examples of final fill subprocesses are also shown in Figure 9. As indicated above, filling re-entrant structures is more challenging and may employ one or more inhibition or etch processes to achieve fill. In one example depicted in Figure 9 for a re-entrant structure, a fill process can use a deposition-etch-deposition (DED) or deposition-inhibition-deposition (DID) process. As described further below, more complex processes including processes with one or more deposition, etch, inhibition, and de -inhibition processes, may be performed to achieve void free fill. Inhibition refers to inhibiting metal nucleation.

[0091] For a DED process, Figure 9 shows examples of two alternative subprocesses - one a discrete intermittent DED and a simultaneous DED. A discrete intermittent DED process may involve a deposition of a first film, followed by a partial etch of that film, followed by a second deposition of a film. For an ALD process, an etch operation may be performed between any number of deposition cycles to tailor the feature profile. One or more DED processes may be performed during the fill.Attorney Docket No. LAM1P057WO-11961-1WO

[0092] For a CVD process, the deposition may be stopped and the etched performed at the appropriate time to tailor the feature profile. A simultaneous DED process can involve adding an etchant to the reducing agent to preferentially etch a portion of the film while depositing. As an example, an etchant such as chlorine (CI2) can be added to the H2 gas during a plasma H2 operation during a PEALD cycle.

[0093] Simultaneous DED may also be referred to a blended DED, with the deposition and etch operations overlapping in time. Figure 9 also has an example of a molybdenum halide -based blended DED. For molybdenum, unlike a molybdenum oxyhalide such as MOO2CI2 or MoOCE, a molybdenum halide such as M0CI5 or MoFe will etch the deposited molybdenum. An example of a blended process may be to lower the H2 and / or increase the molybdenum halide flow to have net etch at the feature opening.

[0094] For a V-shape incoming structure, fill is less challenging and can use any appropriate ALD or CVD process, either thermal or plasma-enhanced. CVD processes include continuous flow and pulsed CVD processes. The subprocesses identified under “V-shaped” structures may be performed for any feature that is relatively easy to fill. In some embodiments, these subprocesses may be used as the final fill operation of a more challenging structure that has been partially filled.

[0095] For final fill operations, the fill material can be molybdenum or another conductive material. Deposition of molybdenum is disclosed further below. Cobalt-containing films can be deposited using a variety of cobalt precursors, where cobalt may be in +1, +2 or +3 oxidation states. Examples of cobalt precursors include cobalt acetate, cobalt acetylacetonates (e.g., cobalt (III) bis(acetylacetonate)), cobalt amidinates (e.g., bis(N-t-butyl-N’- ethylpropanimidamidato)cobalt(II),) cobaltocene, and carbonyl-containing cobalt precursors (e.g., cobalt tricarbonyl nitrosyl, and cyclopentadienylcobalt dicarbonyl). An example of a halogencontaining cobalt precursor is CoC12(TMEDA), where TMEDA is VVVAAetramethylethylenediamine. Ruthenium-containing films metal can be deposited, for example, using vaporizable ruthenium precursors, such as bis(ethylcyclopentadienyl)ruthenium(II), bis(pentamethylcyclopentadienyl)ruthenium, ruthenocene, and cyclopentadi enylpropylcyclopentadienylruthenium(II). Tungsten-containing films can be deposited using a variety of volatile precursors. In some embodiments halogencontaining tungsten precursors, such as WXx, where X is a halogen (e.g., F, Cl, Br, and / or I) and x is from 2 to 6, are used. In some embodiments tungsten chloride is used. Tungsten chloride includes tungsten pentachloride (WCI5), tungsten hexachloride (WCk), tungsten tetrachloride (WCI4), tungsten dichloride (WCh), and mixtures thereof. In other examples tungsten fluoride,Attorney Docket No. LAM1P057WO-11961-1WO such as tungsten hexafluoride may be used. In some embodiments, other useful precursors include vanadium-containing precursors such as tetrakis(dimethylamino)vanadium, tris(dimethylamino)cyclopentadienylvanadium, tetrakis(ethylmethylamino)vanadium; niobium- containing precursors such as (tert-butylimido)bis(diethylamino)niobium, (tert- butylimido)bis(dimethylamino)niobium and (tert-butylimido)bis(ethylmethylamino)niobium; tantalum-containing precursors such as tert-butylimidotris(dimethylamido)tantalum and tantalum pentachloride; iron-containing precursors such as iron (III) tert-butoxide dimer, ferrocene and iron pentcarbonyl; nickel-containing precursors such as allyl(cyclopentadienyl)nickel(II) and nickel(II) bis(acetylacetonate); zinc-containing precursors such as zinc acetate and diethylzinc; and chromium-containing precursors such as chromium carbonyl and bis(cyclopentadienyl)chromium (II).Molybdenum Deposition

[0096] 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.

[0097] In some embodiments, a Mo precursor is a molybdenum chloride (MoClx) compound also referred to as a molybdenum chloride precursor or MoClxprecursor. Molybdenum chloride precursors are given by the formula MoClx, where x is 2, 3, 4, 5, or 6, and include molybdenum dichloride (M0Q2), molybdenum trichloride (M0CI3), molybdenum tetrachloride (M0CI4), molybdenum pentachloride (M0CI5), and molybdenum hexachloride (MoCk). In some embodiments, M0CI5 or MoCk are used. While the description chiefly refers to MoClxprecursors, in other embodiments, other molybdenum halide precursors may be used. Molybdenum halide precursors are given by the formula MoXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)) and z is 2, 3, 4, 5, or 6. Examples of MoXzprecursors include molybdenum fluoride (MoF&). In some embodiments, a non-fluorine -containing MoXzprecursor is used to prevent fluorine etch or incorporation. In some embodiments, a non-bromine-containing and / or a non-iodine-containing MoXzprecursor is used to prevent etch or bromine or iodine incorporation.

[0098] In some embodiments, the feature may be filled using a molybdenum oxy halide precursor. Molybdenum oxyhalide precursors are given by the formula MoOyXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and y and z are numbers greater than 0 such that MoOyXzforms a stable compound. Examples of molybdenum oxyhalides includeAttorney Docket No. LAM1P057WO-11961-1WO molybdenum dichloride dioxide (MOO2CI2), molybdenum tetrachloride oxide (MoOCU), molybdenum tetrafluoride oxide (M00F4), molybdenum dibromide dioxide (MoCLBn), and the molybdenum iodides MOO2I, and MO4O11I. It should be understood that as used herein the term molybdenum oxyhalide precursor may refer to a molybdenum oxyhalide precursor as described above or a molybdenum-containing oxyhalide precursor that includes molybdenum, oxygen, a halide and one or more other elements. In some embodiments, molybdenum oxyhalide or molybdenum-containing oxyhalides may include multiple different halogens (e.g., F and Cl and / or I and / or Br, etc.). A feature may be filled with molybdenum using a MoXxprecursor, MoOyXzprecursor, or a combination thereof.

[0099] For deposition of molybdenum into the feature, the molybdenum precursor may be reacted with a co-reactant. Examples of co-reactants include hydrogen (H2), silane (SiFU), diborane (B2H6), germane (GeFU), ammonia (NH3), and hydrazine (N2H4). Ammonia and hydrazine may be used to deposit molybdenum nitrides or molybdenum oxynitrides.

[0100] 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 NH3. The plasma species may be inert or react with the molybdenum precursor to form a film.

[0101] 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.

[0102] ALD is a surface-mediated deposition technique in which doses of a precursor and a reactant are sequentially introduced into a deposition chamber. One or more cycles of sequential doses of a molybdenum precursor and reactant may be used to deposit Mo. For example, in the deposition of an initial molybdenum layer, M0CI5 may be used as a precursor and H2 as a reducing agent. Doses of M0CI5 and H2 are sequentially introduced into the deposition chamber with a purge gas, such as argon, flowed between. For ALD, the temperature of the substrate and the pressure of the chamber may be controlled. For example, the substrate may be heated between 200°C and 800°C, e.g., between 250°C and 550°C or between 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.Attorney Docket No. LAM1P057WO-11961-1WO

[0103] In some embodiments, the Mo precursor is a molybdenum fluoride (MoFx) compound, also referred to as a molybdenum fluoride precursor or MoFxprecursor. Molybdenum chloride precursors are given by the formula MoFx, where x is 4, 5, or 6, and include molybdenum tetrafluoride (M0F4), molybdenum pentafluoride (M0F5), and molybdenum hexafluoride (MoFe).

[0104] MoFe can be advantageous as it has a boiling point of 34°C. Being a gas at standard pressure and 35°C allows MoFe to be delivered through a mass flow controller (MFC) at room temperature, without heating and without condensing and forming particles. However MoFe is an aggressive etchant and exposure to MoFe during a process can result in etching instead of or in addition to Mo deposition. In some embodiments, deposition using MoFe, involves providing a flow of MoFe in a process gas with the MoFe at a molar concentration of 0.01% or less. Concentration may be significantly lower in some embodiments, for example, 0.008% or less, 0.005% or less, or 0.004% or less. These values can also be expressed as parts per million (ppm) of a gas: 100 ppm (100 MoFe molecules per 1 million gas particles (atoms, molecules)) or less, 80 ppm or less, or 40 ppm or less. At temperatures between 200°C and 650°C, for example, a molar concentration at or below 0.004% results in CVD deposition when flowed with H2 and argon. Higher temperatures may be used to favor the deposition reaction and allow higher concentrations of MoFe, e.g., up to 0.01%. In some embodiments, concentrations may be 0.0039% or .0035% or less. In some embodiments, the MoFe concentration is at least 0.00004% or at least 0.0001%. Concentration may be very low with an exposed metal surface to grow on, for example.

[0105] 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.

[0106] In some embodiments, MoFe may be used at higher concentrations and lower temperatures with a reducing agent that is stronger than that of hydrogen. Lower temperatures can reduce or prevent etching with MoFe; however, at low temperatures 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.Attorney Docket No. LAM1P057WO-11961-1WO

[0107] 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.

[0108] 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.

[0109] 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 generators. A microwave plasma generator may be used.

[0110] 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 deposition

[0111] 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 S i O2 and a TiN plug in a bottom portion of the feature. In selective deposition,Attorney Docket No. LAM1P057WO-11961-1WO 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.

[0112] 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.

[0113] Different precursor gases may have different process windows in which molybdenum film may be selectively deposited. Generally speaking, M0CI5 gas has a large process window, i.e., large temperature and pressure range, where the precursor gas retains its selectivity. For example, M0CI5 may be selectively deposited on a metal material with respect to a dielectric material where the process temperature is 200°C to 800°C, e.g., 250°C to 550°C, or 300°C to 500°C. Generally speaking, higher process temperatures and higher process pressures reduce the selectivity of the deposited gas. M0CI5 deposits selectively on metals, titanium nitride (TiN) and other conductive materials relative to dielectric materials at a wide range of temperatures.

[0114] 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 SiFU, B2H6, NH3, as appropriate. Reactants such as B2H6 and / or S1H4 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 M0CI5 may be between 200°C to 800°C, e.g., 250°C to 550°C, or 300°C to 500°C. At these temperatures, the molybdenum film is selectively deposited on conductive metal or metal compound surfaces, such as a TiN surface, in a feature relative to dielectric surfaces. The molybdenum film grows from the locations where the conductive surfaces are located in a feature. If the conductive surface is a TiN plug at the bottom of the feature, the molybdenum film may be deposited and grown from the bottom of the feature. In a second example, the molybdenum film may be deposited using the M0CI5 precursor and the H2 reactant, but at higher temperatures, i.e., above 800°C. This processAttorney Docket No. LAM1P057WO-11961-1WO 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.

[0115] In some embodiments, selective deposition is performed using a MoFxprecursor. Molybdenum fluoride precursors are given by the formula MoFxas described above. As indicated above, MoFe can be advantageous for ease of delivery. Deposition of 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. MoFe also deposits selectively on metals with respect to dielectric materials, though it is less selective than MoCb. 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.

[0116] 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 MOO2Q2. As indicated above, examples of MoOyXz precursors include MOO2CI2, MoOCU, M00F4, MoO2Br2, MOO2I, and MO4O11L The feature may be filled using ALD, plasma enhanced ALD, chemical vapor deposition (CVD), or plasma enhanced CVD. For ALD or CVD, H2 may be the reducing agent. Molybdenum deposits more quickly using a molybdenum oxyhalide precursor than the MoClxprecursor used in the surface treatment. For example, a MoOyXzprecursor may deposit molybdenum at a deposition rate at least twice as fast as a MoClxprecursor for a non-plasma process.Non-selective Deposition

[0117] The selectivity described 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.

[0118] Examples of plasma processes include plasma-enhanced ALD (PEALD) or plasma enhanced CVD (PECVD) processes using a molybdenum halide precursor. In some embodiments, the molybdenum halide precursor is M0CI5 or MoFe. A molybdenum oxyhalide may also be used, with examples including MOO2CI2 or MoOCU. Hydrogen (H2) or other reducing agent may be used for the PEALD or PECVD deposition.Attorney Docket No. LAM1P057WO-11961-1WO

[0119] 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.

[0120] Non-selective deposition may also be a thermal process using molybdenum oxyhalides. For example, thermal MOO2Q2 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 MOO2Q2 and H2.

[0121] 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 (SiFU) or diborane (B2H6). Germanium- containing reducing agents (e.g., GeFU) 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.

[0122] 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, a bulk molybdenum layer can be deposited using H2 as a reducing agent by any of the methods described above, including thermal or plasma-enhanced ALD or CVD.Attorney Docket No. LAM1P057WO-11961-1WONucleation Layer

[0123] In some embodiments, filling a feature can involve depositing a nucleation layer. A nucleation layer is a thin layer that supports bulk deposition. It may be conformal to the feature. In many embodiments, a nucleation layer is deposited by an ALD process. In some embodiments, a Mo nucleation layer is deposited using one or more of a boron-containing reducing agent (e.g., B2H6) or a silicon-containing reducing agent (e.g., SiFL) as a co-reactant. For example, one or more S / Mo cycles or Mo / S cycles may be used to deposit a Mo nucleation layer. In another example, one or more B / Mo cycles or Mo / B cycles may be used to deposit a Mo nucleation layer on which a bulk Mo layer is deposited. B refers to a pulse of diborane or other boron-containing reducing agent and S to a pulse of silane or other silicon-containing reducing agent, such that S / Mo refers to a pulse of silane followed by a pulse of a Mo-containing precursor. B / Mo and S / Mo cycles (or Mo / B and / or Mo / S) may both be used to deposit a Mo nucleation layer, e.g., x(B / Mo) + y(S / Mo), with x and y being integers. Examples of boron-containing reactants include diborane (B2H6), alkyl boranes, alkyl boron, aminoboranes (CH3)2NB(CH2)2, carboranes such as C2BnHI1+2, and other boranes. Examples of boranes include BnHn+4, BnHn+6, BnHn+8, BnHm, where n is an integer from 1 to 10, and m is a different integer than m. Examples of silicon-containing reducing agents including silane (Si H4) and other silanes such as disilane (Si2He).

[0124] In some embodiments, deposition of a Mo nucleation layer may involve using a non- oxygen-containing precursor, e.g., molybdenum hexafluoride (MoFe) or molybdenum pentachloride (M0CI5). Oxygen in oxygen-containing precursors may react with a silicon- or boron-containing reducing agent to form MoSixOyor MoBxOy, which are impure, high resistivity films. In some embodiments, oxygen-containing precursors may be used for nucleation layer deposition with oxygen incorporation minimized. Oxygen incorporation can be minimized by high reducing agent flows (e.g., greater than 100:1 volumetric flow rate of reducing agent to oxygen-containing Mo precursor).

[0125] In some embodiments, H2 may be used as a reducing gas for Mo nucleation layer deposition instead of a boron-containing or silicon-containing reducing gas. Example thicknesses for deposition of a Mo nucleation layer range from 5 A to 30 A. Films at the lower end of this range may not be continuous; however, as long as they can help initiate continuous bulk Mo growth, the thickness may be sufficient.

[0126] In some embodiments, the reducing agent pulses during deposition of a nucleation or bulk Mo layer may be done at lower substrate temperatures than the Mo precursor pulses. For example,Attorney Docket No. LAM1P057WO-11961-1WO B2H6 or a SikU (or other boron- or silicon-containing reducing agent) pulse may be performed at a temperature below 300°C, with the Mo pulse at temperatures greater than 300°C.

[0127] In some embodiments, the reducing agent is NH3 or other nitrogen-containing reducing agents such as hydrazine (N2H4). NH3 chemisorption on dielectrics is more favorable than that of H2. In some embodiments, the reducing agent and precursor are selected such that they react without reducing agent dissociation. NH3 reacts with metal oxychlorides and metal chlorides without dissociation. This is in contrast to, for example, ALD from metal oxychlorides that use H2 as a reducing agent; H2 dissociates on the surface to form adsorbed atomic hydrogen, which results in very low concentrations of reactive species and low surface coverage during initial nucleation of metal on the dielectric surface. By using NH3 and metal oxychloride or metal chloride precursors, nucleation delay is reduced or eliminated at deposition temperatures up to hundreds of degrees lower than used by H2 reduction of the same metal precursors.

[0128] In some embodiments, the reducing agent may be a boron-containing or silicon-containing reducing agent such as B2H6 or S1H4. These reducing agents may be used with metal chloride precursors, with metal oxychlorides; however, the B2H6 and Si H4 may react with water formed as a byproduct during the ALD process and form solid B2O3 and S1O2. These are insulating and can remain in the film, increasing resistivity. Use of NH3 also has improved adhesion over B2H6 and SitL ALD processes on certain surfaces including AI2O3. The resulting nucleation layer is generally not a pure elemental film but a metal nitride or metal oxynitride film. In some embodiments, there may be residual chlorine or fluorine from the deposition, particularly if the deposition is performed at low temperatures. In some embodiments, there may be no more than a trace amount of residual chlorine or fluorine. In some embodiments, the nucleation layer is an amorphous layer. Impurities in the film (e.g., oxygen, NH3, chlorine, or other halogens) facilitate the growth of an amorphous microstructure. In some embodiments, the nucleation layer as deposited is an amorphous molybdenum oxynitride layer or an amorphous molybdenum nitride layer. The amorphous character templates large grain growth in the subsequently deposited conductor. The surface energy of nitride or oxynitride relative to an oxide surface is much more favorable than that of a metal on an oxide surface, facilitating formation of a continuous and smooth film on the dielectric. This allows formation of thin, continuous layers. Example thicknesses of the nucleation layer range from 5-30A as deposited. Depending on the temperature, this may be about 5-50 ALD cycles, for example.Attorney Docket No. LAM1P057WO-11961-1WOIntegration processes including etch and / or inhibition

[0129] Etch operations may be used in the methods for filling features with Mo films. Etch operations remove materials such as metals and nitrides from the feature. For example, an etch process may partially or completely remove a liner (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.

[0130] 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 (Ch), 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 (CaFs), hexafluorobutadiene (C4F6), hexafluorocyclopentadiene (C5F6), carbon tetrafluoride (CF4), carbon tetrafluoride (CCU), nitrogen trifluoride (NF3), boron trichloride (BCI3), boron trifluoride (BF3), hydrogen iodide (HI), hydrogen bromide (HBr), sulfur tetrafluoride (SF4), sulfur hexafluoride (SFe), thionyl chloride (SOCI2), phosphorus pentafluoride (PF5), phosphorus trifluoride (PF3), silicon tetrabromide (SiBri), 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 oxygen. 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 halogencontaining etchant may be co-flowed with a non-halogen containing etchant.

[0131] In some embodiments, the etchant is M0CI5, M0E5, WEs, 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 MoClxsuch as M0CI5. In some embodiments, the soak may be done continuously with the Mo halide gas. In some embodiments, the soak may be pulsed, cycling the Mo halide with a purge gas, such as argon (Ar).

[0132] 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 andAttorney Docket No. LAM1P057WO-11961-1WO 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.

[0133] In some embodiments, the MoClxprecursor at high temperatures, e.g., above 550°C, may continue to etch material at a faster rate than depositing material. For example, M0CI5 may be used to etch a feature by a soak without a reactant. In this example, the temperature may be as high as 700°C and will continue to etch away material from the feature. In operations where the feature is soaked in a M0CI5 without a reactant, the increased temperature may increase the rate at which material is etched from the feature.

[0134] In some embodiments, an etch as described above with respect to operations 503 and 505 is performed.

[0135] 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 MoClxcompounds are given above. A Cl-containing precursor may be used where traditional cleaning with thermal or plasma H2 does not work, such as where the oxidized surface is stable on the surface material. A Cl-containing precursor is less likely to over-etch a feature’s liner layer or attack a feature’s surfaces than an F-containing compound.

[0136] 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. LAM1P057WO-11961-1WO

[0137] 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.

[0138] A dielectric material may be treated with a halogen-containing chemistry to inhibit molybdenum nucleation. Examples include F2, NF3, BCI3, M0CI5, and CI2. Each of these chlorinates or fluorinates oxides inhibiting further nucleation.

[0139] Inhibition operations may also be performed as part of deposition-inhibition-deposition (DID) techniques. In some embodiments, a portion of a molybdenum film 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.

[0140] As noted above, 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 alkyl halide, such as t-butyl chloride or t-butyl iodide). In some embodiments, the halogencontaining compound is an iodine-containing compound. Further examples of inhibitors include trimethylsilylchloride [(CHshSiCl] and trimethylsilyl-dimethylamide [(CHs SiN / CHs - 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.

[0141] 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. LAM1P057WO-11961-1WO

[0142] 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.

[0143] 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.

[0144] 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 CI2. 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.

[0145] 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. LAM1P057WO-11961-1WO

[0146] A process may use various permutations of Dep 1 , Dep2, Etch, Inhibition and de-lnhibition 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-lnhibition - DepDep - Inhibition - Etch - DepDep - Etch - Dep - Inhibition - DepDep - Etch - Dep - Inhibition - Dep - de-lnhibition - DepDep - Inhibition - Dep - Etch - DepDep - Oxidation - Etch - DepDep - Nitridation - Etch - Dep

[0147] In some embodiments, the dep-etch-dep operations disclosed herein may be integrated into single chamber metallization processes as described above.Apparatus

[0148] Figure 10 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 multi-station processing system 1100. 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.

[0149] ALD process station 1000 fluidly communicates with reactant delivery system 1001a for delivering process gases to a distribution showerhead 1006. Reactant delivery system 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,Attorney Docket No. LAM1P057WO-11961-1WO deposition of an initial Mo layer is performed in process station 1000 and in some embodiments, other operations such as in-situ clean or Mo gap fill may be performed in the same or another station of the multi-station processing system 1100 as further described below with respect to Figure 11 A.

[0150] As an example, the embodiment of Figure 10 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.

[0151] 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.

[0152] 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. A plunger valve of the LFC may then be adjusted responsive to feedback control signals provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, it may take one second or more to stabilize liquid flow using feedback control. This may extend a time for dosing a liquid reactant. Thus, in some embodiments, the LFC may be dynamically switched between a feedback control mode and a direct control mode. In some embodiments, this may be performed by disabling a sense tube of the LFC and the PID controller.

[0153] Showerhead 1006 distributes process gases toward substrate 1012. In the embodiment shown in Figure 10, 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. LAM1P057WO-11961-1WO

[0154] In some embodiments, pedestal 1008 may be raised or lowered to expose substrate 1012 to a volume between the substrate 1012 and the showerheadl0706. In some embodiments, pedestal 1108 may be temperature controlled via heater 1010. Pedestal 1008 may be set to any suitable temperature, such as between about 250°C and about 800°C during operations for performing various disclosed embodiments. It will be appreciated that, in some embodiments, pedestal height may be adjusted programmatically by a suitable computer controller 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.

[0155] In some embodiments, a position of showerhead 1006 may be adjusted relative to pedestal 1008 to vary a volume between the substrate 1012 and the showerhead 706. Further, it will be appreciated that a vertical position of pedestal 1008 and / or showerhead 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.

[0156] 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.

[0157] 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. LAM1P057WO-11961-1WO 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.

[0158] 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 an inert and / or a reactant gas (e.g., a Mo precursor), instructions for setting a flow rate of a carrier gas (such as argon), and time delay instructions for the first recipe phase. A second, subsequent recipe phase may include instructions for modulating or stopping a flow rate of an inert and / or a reactant gas, and instructions for modulating a flow rate of a carrier or purge gas and time delay instructions for the second recipe phase. A third recipe phase may include instructions for modulating a flow rate of a second reactant gas such as H2, instructions for modulating the flow rate of a carrier or purge gas, instructions for igniting a plasma, and time delay instructions for the third recipe phase. A fourth, subsequent recipe phase may include instructions for modulating or stopping a flow rate of an inert and / or a reactant gas, and instructions for modulating a flow rate of a carrier or purge gas and time delay instructions for the fourth recipe phase. It will be appreciated that these recipe phases may be further subdivided and / or iterated in any suitable way within the scope of the present disclosure.

[0159] Further, in some embodiments, pressure control for process station 1000 may be provided by butterfly valve 1018. As shown in the embodiment of Figure 10, 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.

[0160] Figure 11A and Figure 11B show examples of processing systems. Figure 11A shows an example of a processing system including multiple chambers. The system 1100 includes a transferAttorney Docket No. LAM1P057WO-11961-1WO 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. Mounted on the transfer module 1103 is a multi-station chamber 1109 capable of performing in- situ clean and / or ALD processes described above. Surface treatment and / or initial Mo layer deposition may be performed in the same or different station or chamber as the subsequent metallization.

[0161] Chamber 1109 may include 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 performs an in-situ treatment using a MoClx precursor. Station 1113 may be configured to selectively treat the field region and upper si de walls and station 1115 may be configured to perform ALD of a conformal liner layer using a molybdenum oxyhalide precursor and H2. Station 1117 may be configured to etch. In another example, chamber 1109 may be configured such that station 1111 performs in-situ clean, station 1113 performs ALD of a conformal molybdenum layer, stations 1115 and 1117 perform bulk deposition of a fill metal. In another example, the chamber 1109 may be configured to do parallel processing of substrates, with each station performing multiple processes sequentially.

[0162] 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 liner layer in a first station followed by ALD 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.

[0163] Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0164] Also mounted on the transfer module 1103 may be one or more single or multi -station modules 1107. In some embodiments, a preclean as described above may be performed in a module 1107, after which the substrate is transferred under vacuum to another module (e.g., another module 1107 or chamber 1109) for ALD. In another example, a module for selective treatment of a film may be mounted on the transfer module.

[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 waferAttorney Docket No. LAM1P057WO-11961-1WO 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 modulell803.

[0166] Referring to Figure 9, for example, in some embodiments, chamber 1109 is configured to perform any subset of pre-treatment, selective fill, conformal liner deposition, etch, and final fill. In one example, station 1111 is configured to perform selective fill, station 1113 is configured to perform conformal liner deposition, station 1115 is configured to perform etch, and station 1117 is configured to perform final fill. In another example, station 1111 is configured to perform pretreatment, station 1113 is configured to conformal deposition, station 1113 is configured to perform inhibition, and station 1115 is configured to perform final fill.

[0167] Chamber 1109 may have one or more of the following features to enable single chamber metallization processes: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.

[0168] Solid precursor delivery systems may include bulk delivery systems and / or on-board ampoules.

[0169] 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 1 IB has three single station modules 1157a-1175c. The system 1100 may be configured to sequentially perform operations in accordance with the disclosed embodiments. For example, the single station modules 1157a-1157c may be configured so that a first module 1157a performs a surface treatment, a second module 1157b performs ALD of an initial Mo layer using a molybdenum oxyhalide halide precursor, and a third module 1157c performs etch.

[0170] 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 10.

[0171] Returning to Figure 1 1 A and 11 B, 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 CPUAttorney Docket No. LAM1P057WO-11961-1WO 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.

[0172] 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.

[0173] 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 process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0174] 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 instractions that may be executed on a general-purpose processor. System control software may be coded in any suitable computer readable programming language.

[0175] 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.

[0176] 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.Attorney Docket No. LAM1P057WO-11961-1WO

[0177] 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.

[0178] 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.

[0179] 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, 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.

[0180] 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 fonn 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 moreAttorney Docket No. LAM1P057WO-11961-1WO processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0181] 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. In some examples, the controller receives instractions 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.

[0182] 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.

[0183] 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 thatAttorney Docket No. LAM1P057WO-11961-1WO bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0184] 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.

[0185] 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.

[0186] 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. LAM1P057WO-11961-1WOCLAIMSWhat is claimed is:

1. A method comprising : depositing a conformal molybdenum film in a feature on a substrate by an atomic layer deposition (ALD) process, wherein the feature is formed within a layer on the substrate and is surrounded by a field region and comprises a bottom surface and sidewall surfaces that extend from the field region to the bottom surface, wherein the ALD process comprises multiple cycles of: a) exposing the substrate to a molybdenum precursor; b) exposing the substrate to a reducing agent; and c) exposing the substrate to an etchant.

2. The method of claim 1, wherein (c) preferentially etches molybdenum on the field region with respect to molybdenum within the feature.

3. The method of claim 1, wherein (b) is a plasma-based operation.

4. The method of claim 1, wherein (c) is a plasma-based operation.

5. The method of claim 1 , wherein the reducing agent comprises one or more of hydrogen gas and plasma species generated from hydrogen gas.

6. The method of claim 1 , wherein the etchant comprises one or more of chlorine gas and plasma species generated from chlorine gas.

7. The method of claim 1, wherein a flow rate the reducing agent is at least twice that of the etchant.

8. The method of claim 1, wherein (b) and (c) are sequential and non-overlapping.

9. The method of claim 1, wherein (b) and (c) are at least partially overlapping.

10. The method of claim 1, further comprising filling the feature with a conductive material.

11. The method of claim 10, wherein the conductive material is selected from tungsten (W), cobalt (Co), ruthenium (Ru), molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), and titanium nitride (TiN).

12. The method of claim 1, wherein the bottom surface is a conductive material and the sidewall surfaces are dielectric material.

13. The method of claim 1, wherein the etchant is selected from: boron trichloride (BCh), carbon tetrachloride (CCI4), thionyl chloride (SOCh), sulfur hexafluoride (SFe), trifluorochloride (CIF3), nitrogen trifluoride (NF3), phosphorous trifluoride (PF3), molybdenum pentachloride (M0CI5), molybdenum hexafluoride (MoFe), and plasma species generated therefrom.Attorney Docket No. LAM1P057WO-11961-1WO14. A method comprising: depositing a conformal molybdenum film in a feature on a substrate by an atomic layer deposition (ALD) process, wherein the feature is formed within a layer on the substrate and is surrounded by a field region and includes a bottom surface and sidewall surfaces that extend from the field region to the bottom surface; etching the conformal molybdenum film to remove it from the bottom surface, leaving the conformal molybdenum film on sidewall surfaces; and depositing a conductive material to fill the feature, wherein the conductive material contacts the bottom surface.

15. The method of claim 14, wherein the conductive material is selected from tungsten (W), cobalt (Co), ruthenium (Ru), molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), and titanium nitride (TiN).

16. The method of claim 14, wherein etching the conformal molybdenum film comprises exposing the substrate to an etchant selected from: chlorine (Ch), boron trichloride (BCh), carbon tetrachloride (CCU), thionyl chloride (SOCh), sulfur hexafluoride (SFe), trifluorochloride (CIF3), nitrogen trifluoride (NF3), phosphorous trifluoride (PF3), molybdenum pentachloride (M0CI5), molybdenum hexafluoride (MoFe), and plasma species generated therefrom.

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