Reducing line bending during metal fill process

Abstract

Methods of mitigating line bending during feature fill include changing deposition conditions to reduce interatomic forces within the features. Deposition may be thermal or plasma-enhanced according to various embodiments. In some embodiments, plasma-enhanced atomic layer deposition techniques including seam formation within a feature are employed.

Description

Attorney Docket No.: LAM1P104WO-12234-1WO REDUCING LINE BENDING DURING METAL FILL PROCESS INCORPORATION BY REFERENCE

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

[0001] Deposition of conductive materials 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.

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

[0003] One aspect of the disclosure relates to a method including: providing a substrate having a plurality of features spaced apart, the features including sidewalls and one or more openings; depositing a molybdenum layer at a first set of deposition conditions, wherein the molybdenum layer grows from the side alls of each feature to a center of the feature; and as the molybdenum layer approaches the feature centers, changing the deposition conditions to a second set of deposition conditions to reduce interatomic force between molybdenum on opposing sidewalls of each feature.

[0004] In some embodiments, each feature of the plurality’ of features is a vertically-oriented feature having one opening and a feature bottom. In some such embodiments, each of the plurality of features narrows from the opening to the feature bottom.

[0005] In some embodiments, each feature of the plurality of features are horizontally-oriented.

[0006] In some embodiments, the first set of deposition conditions has a first temperature, the second set of deposition conditions has a second temperature, wherein the second temperature is at least 50°C lower than the first temperature.

[0007] In some embodiments, the first set of deposition conditions has a first temperature, theAttorney Docket No.: LAM1P104WO-12234-1WO second set of deposition conditions has a second temperature, wherein the second temperature is at least 100°C lower than the first temperature.

[0008] In some embodiments, transitioning from the first set of deposition conditions to the second set of deposition conditions includes lowering a substrate temperature, and wherein the method further includes raising the temperature to deposit an overburden layer on the plurality of features. In some embodiments, the first set of deposition conditions includes a four-step atomic layer deposition (ALD) process and the second set of deposition conditions includes a six-step ALD process.

[0009] In some such embodiments, the four-step ALD process includes alternating doses of a molybdenum-containing precursor and a reducing agent separated by purges and wherein the six-step ALD process includes alternating doses the molybdenum-containing precursor, the reducing agent, and a third chemistry, separated by purges.

[0010] Examples of the third chemistry include an oxidizing agent, a nitrogen-containing chemistry, and a halogen-containing chemistry.

[0011] In some embodiments, depositing the molybdenum layer at the first set of deposition conditions includes performing an ALD process at first chamber pressure and wherein changing the deposition conditions includes lowering the chamber pressure for one or more steps of the ALD process.

[0012] In some embodiments, the method further includes depositing a molybdenum-containing liner layer in the plurality of features including on the sidewalls, prior to depositing the molybdenum layer such that the molybdenum layer is deposited on the liner layer.

[0013] In some embodiments, the method further includes depositing additional layers such that a stack including a plurality of molybdenum / molybdenum oxynitride bilayers is deposited in the feature.

[0014] Another aspect of the disclosure relates to a method including: providing a substrate having a plurality of features spaced apart, the features including sidewalls and one or more openings; and depositing molybdenum within the plurality of features using an atomic layer deposition (ALD) process, wherein the ALD process includes a cycle including: a reducing agent dose and a molybdenum-containing precursor dose and wherein a chamber pressure of a chamber housing the substrate is lower during the reducing agent dose than during the molybdenum precursor dose.

[0015] A aspect of the disclosure relates toa method including: providing a substrate having a plurality of vertically-oriented features spaced apart, the features including sidewalls and anAttorney Docket No.: LAM1P104WO-12234-1WO opening; and reacting a molybdenum precursor with hydrogen plasma species to grow a molybdenum layer from the sidewalls of each feature to the feature center to thereby fill the features under conditions such that a seam is formed within each feature.

[0016] In some embodiments, the features are 2-D DRAM features and the molybdenum is deposited directly on a gate oxide layer.

[0017] In some embodiments, the method further includes depositing molybdenum on the filled features.

[0018] In some embodiments, the molybdenum precursor is reacted with hydrogen plasma species in a plasma-enhanced ALD process.

[0019] In some embodiments, the molybdenum precursor is reacted with hydrogen plasma species in a plasma-enhanced chemical vapor deposition (CVD) process.

[0020] In some embodiments, the substrate temperature during grow th of the molybdenum layer is 500°C or less.

[0021] These and other aspects of the disclosure are described further below with reference to the drawings.BRIEF DESCRIPTION OF DRAWINGS

[0022] Figures 1A and IB are schematic examples of material stacks that include Mo layers according to various embodiments.

[0023] Figure 2A depicts a schematic example of a DRAM architecture including a buried wordline (bWL) in a silicon substrate.

[0024] Figure 2B shows an unfilled and filled narrow asymmetric trench structure for DRAM bWLs that exhibit line bending after fill.

[0025] Figure 2C depicts a schematic illustration of line bending.

[0026] Figure 2D depicts a schematic illustration of a zipping phenomenon.

[0027] Figures 3A-3K are schematic examples of various structures in which molybdenum or other metal may be deposited in accordance with disclosed embodiments.

[0028] Figures 4 and 5 are process flow diagrams that shows operations in methods according to various embodiments that may be used to reduce line bending.

[0029] Figure 6 shows a representation of a quad-station module including four stations that may be used to perform methods described herein.Attorney Docket No.: LAM1P104WO-12234-1WO

[0030] Figure 7 shows an example of molybdenum deposition in features on a substrate by an atomic layer deposition (ALD) process.

[0031] Figure 8 shows operations in a method of an ALD super-cycle used to mitigate line bending.

[0032] Figure 9 shows a schematic diagram of feature fill with unmitigated thermal conformal ALD compared with plasma-enhanced ALD (PE ALD) processes.

[0033] Figure 10 shows a comparison of feature fill of a 2D DRAM structure using thermal ALD (top) and PEALD (bottom).

[0034] Figure 11 shows example operations in a multi-station chamber used to deposit a conformal layer of molybdenum on the gate oxide, followed by fill including seam formation, and an overburden layer.

[0035] Figures 12-14 show schematic diagrams of apparatuses that may be used to implement the methods described herein.DESCRIPTION

[0036] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all 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 specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

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

[0038] Provided herein are methods of filling features with metal that may be used for logic and memory applications. The metal films may be deposited in semiconductor substrate features such as wordline features, vias, trenches. While described chiefly in the context of molybdenum (Mo), the methods may be used for deposition of other metals including tungsten (W).cobalt (Co), and ruthenium (Ru).

[0039] Figures 1A and IB are schematic examples of material stacks that include Mo layers according to various embodiments. Figures 1 A and IB illustrate the order of materials in examples of particular stacks and may be used with any appropriate architecture and application, as describedAttorney Docket No.: LAM1P104WO-12234-1WO further below. Figure 1A shows a first material stack 111 featuring a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 may be a silicon or other semiconductor wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semi-conducting material deposited thereon. In some embodiments, the substrate 102 may be or include silicon (Si) or silicon germanium (SiGe). The methods may also be applied to form metallization stack structures on other substrates, such as glass, plastic, and the like.

[0040] The stack 111 has a dielectric layer 104 on the substrate 102. The dielectric layer 104 may be deposited directly on a semiconductor surface (e.g., a Si or SiGe surface) of the substrate 102, or there may be any number of intervening layers. For example, the substrate 102 may include any number of layers deposited in various arrangements on a semiconductor surface.

[0041] Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, with specific examples including doped or undoped layers of silicon nitride (SiN), silicon dioxide (SiCh), and aluminum oxide (AI2O3). The stack 111 has a layer 106 disposed between the molybdenum layer 108 and the dielectric layer 104. The layer 106 may be a diffusion barrier and / or an adhesion layer, for example. A diffusion barrier is a layer that prevents diffusion of species between layers. An adhesion layer is a layer that promotes adhesion of a layer to an underlying layer. Examples of diffusion barrier and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten (W), tungsten nitride (WN), and tungsten carbon nitride (WCN). The molybdenum layer 108 is the main conductor of the structure. In some embodiments, the molybdenum layer 108 may include multiple bulk layers deposited at different conditions. The molybdenum layer 108 may or may not include a molybdenum nucleation layer. In the depicted example of Figure 1A, the molybdenum layer 108 is deposited directly on the layer 106. In other embodiments (not depicted), the molybdenum layer 108 may be deposited on a separate layer such as a growth initiation layer that includes another material, such as a tungsten (W) or W-containing growth initiation layer. The growth initiation layer may be used to facilitate nucleation and growth of the molybdenum layer 108.

[0042] 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. The molybdenum layer 108 is as described with respect to Figure 1A. By using molybdenum as the main conductor, low resistivity thin films can be obtained. Examples of low resistivity thin films include films with resistivity less than 40 uOhm-cm at 60 angstroms thickness and less than 15 uOhm-cm at 200 angstroms thickness.Attorney Docket No.: LAM1P104WO-12234-1WO

[0043] In some embodiments, a stack (not shown) may include the substrate, a conductive layer, and a molybdenum layer deposited onto the conductive layer. As used herein, a conductive layer is a layer having a conductivity of at least 104Q''-cm_|at 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) or molybdenum on a metal silicide layer (e.g., TiSix, TiNSix, or MoSix). In still some other embodiments of a stack (not shown), the stack may include a substrate and a molybdenum layer deposited directly on the substrate, including directly on a semiconducting surface, on a dielectric surface, or on a conductive surface. Figures 1A and IB illustrate examples of the order of materials in a particular stack and may be used with any appropriate architecture and application, with examples described further below.

[0044] The methods described herein are performed on a substrate that may be housed in a chamber. The substrate may be a silicon or other semiconductor wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semiconducting material deposited thereon. The methods are not limited to semiconductor substrates and may be performed to fdl any feature with molybdenum.

[0045] Substrates may have features such as vias or contact holes, which may be characterized by one or more narrow and / or re-entrant openings, constrictions within the feature, and high aspect ratios. A feature may be formed in one or more of the above-described stacks or layers within a stack. For example, the feature may be formed at least partially in a dielectric layer. In some embodiments, a feature may have an aspect ratio of at least about 2:1, at least about 4:1, at least about 6: 1 , at least about 10: 1 , at least about 25: 1 , or higher. One example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate. A feature may include one or more different surfaces. For example, in some embodiments, a feature may have a bottom or interior conductive surface and dielectric sidewalls.

[0046] Metal fdl of features is used in semiconductor device fabrication to form electrical contacts. There are various challenges in fdling features with metal as devices scale to smaller technology nodes and more complex patterning structures are used. One challenge in feature fdl is reducing resistance. Low resistivity' fdms minimize power losses and overheating in integrated circuit designs. Thinner fdms have higher resistance than thicker fdms. As features become smaller, the metal contact or line resistance increases due to scattering effects in the thinner fdms. As described above, bulk metal fdms can be deposited on barrier and / or nucleation layers in some embodiments. Nucleation layers typically have higher electrical resistivities than the overlyingAttorney Docket No.: LAM1P104WO-12234-1WO bulk layers. Barrier layers may also have high resistivities. Further, thin barrier and nucleation films occupy a larger percentage of smaller features, increasing the overall resistance in the feature.

[0047] Yet another challenge in metal fill is reducing stress on deposited films. Thinner films tend to have increased tensile stress. High thermal tensile stress causes the substrate to curl, which makes subsequent processing difficult. For example, subsequent processes may include chemical mechanical planarization, deposition of materials, and / or clamping of the substrate to a substrate holder to perform processes in a chamber. However, these processes often rely on the substrate being flat, and a curled substrate results in non-uniform processing or inability to process the substrate.

[0048] Another challenge is reducing line bending. Line bending is a phenomenon resulting from filling multiple adjacent features. During the fill process, the features may bend away from or toward each other, changing the feature shape. Line bending can occur in memory structures such as dynamic random-access memory (DRAM) buried wordline structures (bWL), 3D DRAM structures, and 3D NAND flash memory' structures, as well other logic or memory structures that include multiple adjacent features.

[0049] Line bending during fill of wordlines or other features is believed to be caused by grain boundary merging. This is also referred to as a “zipping” mechanism. When the grain boundaries are formed, the metal-metal bonding between adjacent surfaces causes strain that leads to bending of the matenal separating the wordlines (e.g., silicon separating buried wordlmes). During a fill process, the metal-metal bonding from opposing sidewalls can lead to zipping. Atomic layer deposition (ALD) and chemical vapor deposition (CVD) fill techniques can result in severe bending of the bWL structures. This line bending can cause recess non-uniformity and contact landing issues in downstream processes, which results in yield loss. ALD can be used to form exhibit low stress, low fluorine, and low resistivity films but only on surfaces that allow for such growth. As devices shrink and features are narrower, the potential for line bending during feature fill increases.

[0050] The methods and related apparatus described herein provide feature fill techniques that mitigate line bending and lower resistivity. Particular embodiments relate to methods and related apparatus for formation of wordlines in memory devices. Figure 2A depicts a schematic example of a DRAM architecture including a buried wordline (bWL) 1 1 in a silicon substrate 9. The bWL 11 is formed in a trench etched in the silicon substrate 9. The bWL 11 may be tungsten deposited in the silicon substrate 9 and is capped by SiN passivation layer 5. Lining the trench are a conformal barrier layer 12 and a conformal insulating layer 13. The conformal insulating layer 13 is between the conformal barrier layer 12 and the silicon substrate 9. In the example of Figure 2A,Attorney Docket No.: LAM1P104WO-12234-1WO the insulating layer 13 may be a gate oxide layer formed from a material such as a silicon oxide. Examples of conformal barrier layers include TiN and tungsten-containing barrier layers. Tungsten-containing conformal barrier layers can include binary compounds such as WBX, WSix, WGex, WCx, WNx, ternary compounds such as WBxNy, WSixNy, WGexNy, WSixCy, WBxCy, WGexCy,WCxNy. and quaternary compounds such as WBxGeyNz, WGexCyNz. etc. wherein x, y and z are numbers greater than zero. In some embodiments, as discussed further below, the fill process is performed directly on the conformal insulating layer 13 with no barrier layer present.

[0051] Fill processes for DRAM bWL trenches can distort the trenches such that the final trench width and resistance Rs are significantly non-uniform. Figure 2B shows an unfilled (201) and filled (205) narrow asymmetric trench structure for DRAM bWLs that exhibit line bending after fill. As shown, multiple features are depicted on a substrate. These features are spaced apart, and in some embodiments, adjacent features have a pitch between about 5 nm and about 60 nm, or about 20 nm and about 60 nm, or between about 10 nm and 30 nm, or between about 10 nm and 40 nm, or between about 20 nm and 40 nm. The pitch is defined as the distance between the middle axis of one feature to the middle axis of an adjacent feature. The unfilled features may be generally V-shaped as shown in feature 203, 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 213b to the feature top 213a. After fill, severe line bending is observed in substrate 205. Without being bound by a particular theory, it is believed that a cohesive force between opposing surfaces of a trench pulls the trench sides together as depicted by arrows 207. This phenomenon is illustrated in Figure 2C. As described above, it may be characterized as zipping up the feature. As the feature 203 is filled, more force is exerted from a center axis 299 of the feature 203, causing line bending. Deposited molybdenum 243 a and 243b on sidewalls of feature 203 thereby interact in close proximity, where tungsten-tungsten bond radius r is small. This causes cohesive interatomic forces between the smooth growing surfaces of molybdenum, pulling the sidewalls together. The result is line bending. Figure 2D qualitatively illustrates the interatomic force as a function of molybdenum-molybdenum bond radius, r. As can be seen, a cohesive force exists at certain values of r. Even low stress films deposited by ALD processes can cause severe line bending during the fill. While V-shaped features are described herein, the methods may be applied advantageously with features of any profile that undergo line bending during feature fill.

[0052] Described herein are methods of filling features with metal and related systems and apparatuses to reduce line bending. Although various examples and embodiments herein are described with respect to molybdenum, it will be understood that disclosed embodiments are suitable for depositing a variety of metals, including but not limited to ruthenium (Ru), tungstenAttorney Docket No.: LAM1P104WO-12234-1WO (W), cobalt (Co), and more. Examples of applications include logic and memory contact fill, DRAM buried wordline fill, 3D-NAND wordline fill, 3D-DRAM wordline fill, other vertically integrated memory gate / wordline fill, and 3-D integration with through-silicon vias (TSVs). The methods described herein can be used to fill vertical features, such as in vias and / or 2D memory structures, and horizontal features, such as 3D-NAND wordlines. The methods may be used for conformal and bottom-up or inside-out fill.

[0053] Methods described herein are performed on a substrate that may be housed in a chamber. The substrate may be a silicon wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semi-conducting material deposited thereon. Substrates have features such as via or contact holes, which may be characterized by one or more of V-shaped sidewalls, 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 layers. For example, the feature may be formed at least partially in a dielectric layer. In some embodiments, a feature may have an aspect ratio of at least about 2: 1, at least about 4:1, at least about 6:1, at least about 10:1, or higher. One example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate. Features may be spaced apart on the substrate by a pitch between adjacent features of about 5 nm to 60 nm.

[0054] Figures 3A-3K are schematic examples of various structures in which molybdenum or other metal may be deposited in accordance with disclosed embodiments. Figure 3A shows an example of a cross-sectional depiction of a vertical feature 301 to be filled with metal. The feature 301 can include a feature hole 305 in a substrate 303. The hole 305 or other feature may have a dimension near the opening, e.g., an opening diameter or line width of between about lO nm to 500 nm, for example between about 25 nm and about 300 nm. The feature hole 305 can be referred to as an unfilled feature or simply a feature. The feature 301, and any feature, may be characterized in part by an axis 318 that extends through the length of the feature through the center of the hole 305, with vertically-oriented features having vertical axes and horizontally-oriented features having horizontal axes.

[0055] In some embodiments, features are trenches in a 3D NAND structure. For example, a substrate may include a wordline structure having at least 60 lines, with 18 to 48 layers, or hundreds of layers, with trenches at least 200A deep or many microns deep. Another example is a trench in a substrate or layer. Features may be of any depth. In various embodiments, the feature may have an under-layer, such as a barrier layer or adhesion layer. Non-limiting examples of under-layers include dielectric layers and conducting layers, e.g., silicon oxides, silicon nitrides, silicon carbides, metal oxides, metal nitrides, metal carbides, and metal layers.Attorney Docket No.: LAM1P104WO-12234-1WO

[0056] Figure 3B shows an example of a feature 301 that has a re-entrant profile. A re-entrant profile is a profile that narrows from a bottom, closed end, or interior of the feature to the feature opening. According to various implementations, the profile may narrow gradually and / or include an overhang at the feature opening. Figure 3B shows an example of the latter, with an under-layer 313 lining the sidewall or interior surfaces of the feature hole 305 of feature 301. The under-layer 313 can be for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination of thereof, or any other applicable material. Non-limiting examples of under-layers can include dielectric layers and conducting layers, e.g., silicon oxides, silicon nitrides, silicon carbides, metal oxides, metal nitrides, metal carbides, and metal layers. In particular implementations, an under-layer can be one or more of titanium (Ti), titanium nitride (TiN), tungsten nitride (WN), titanium aluminide (TiAl), and tungsten (W). The under-layer 313 forms an overhang 315 such that the under-layer 313 is thicker near the opening of the feature 301 than inside the feature 301. In the examples of Figures 3 A and 3B, features having vertical sidewalls are shown. However, as indicated above, in some embodiments, the feature width may narrow from top to bottom.

[0057] In some implementations, features having one or more constrictions within the feature may be filled. Figure 3C shows examples of views of various filled features having constrictions. Each of the examples (a), (b) and (c) in Figure 3C includes a constriction 309 at a midpoint within the feature. The constriction 309 can be, for example, between about 15 nm-20 nm wide. Constrictions can cause pinch off during deposition of metal 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 a liner / barrier overhang 315 at the feature opening. Such an overhang could also be a potential pinch-off point. Example (c) includes a constriction 312 further away from the field region than the overhang 315 in example (b). A feature having a constriction may narrow from top to bottom in some embodiments. Horizontal features, such as in 3-D memory structures, can also be filled. Figure 3D shows an example of a horizontal feature 350 that includes a constriction 351. For example, horizontal feature 350 may be a word line in a 3D NAND structure.

[0058] In some implementations, the constrictions can be due to the presence of pillars in a 3D NAND or other structure. Figure 3E, for example, shows a plan view of pillars 325 in a 3D NAND or vertically integrated memory (VIM) structure 348, with Figure 3F showing a simplified schematic of a cross-sectional depiction of the pillars 325. Arrows in Figure 3E represent deposition material. Because pillars 325 are disposed between an area 327 and a gas inlet or other deposition source, adjacent pillars can result in constrictions 351 that present challengesAttorney Docket No.: LAM1P104WO-12234-1WO in void free fill of an area 327.

[0059] The structure 348 can be formed, for example, by depositing a stack of alternating interlayer dielectric layers 329 and sacrificial layers (not shown) on a substrate 300 and selectively etching the sacrificial layers. The interlayer dielectric layers may be, for example, silicon oxide and / or silicon nitride layers, with the sacrificial layers a material selectively etchable with an etchant. This may be followed by etching and deposition processes to form pillars 325, which can include channel regions of the completed memory device.

[0060] The main surface of substrate 300 can extend in the x and y directions, with pillars 325 oriented in the z-direction. In the example of Figures 3E and 3F, pillars 325 are arranged in an offset fashion, such that pillars 325 that are immediately adjacent in the x-direction are offset with each other in the y-direction and vice versa. According to various implementations, the pillars (and corresponding constrictions formed by adjacent pillars) may be arranged in any number of manners. Moreover, the pillars 325 may be any shape including circular, square, etc. Pillars 325 can include an annular semi-conducting material, or circular (or square) semi-conducting material. A gate dielectric may surround the semi-conducting material. The area between each interlayer dielectric layer 329 can be filled with molybdenum or other metal; thus structure 348 has a plurality of stacked horizontally-oriented features that extend in the x and / or y directions to be filled.

[0061] Figure 3G provides another example of a view of a horizontal feature, for example, of a 3D NAND or other structure including pillar constrictions 351. The example in Figure 3G is open-ended, with material to be deposited able to enter horizontally from two sides as indicated by the arrows. (It should be noted that example in Figure 3G can be seen as a 2-D rendering 3-D features of the structure. Figure 3G is a cross-sectional depiction of an area to be filled and pillar constrictions shown in the figure representing constrictions that would be seen in a plan rather than cross-sectional view.) In some implementations, 3-D structures can be characterized with the area to be filled extending along two or three dimensions (e.g., in the x and y or x, y and z-directions in the example of Figure 3F), and can present more challenges for fill than filling holes or trenches that extend along one or two dimensions. For example, controlling fill of a 3-D structure can be challenging as deposition gasses may enter a feature from multiple dimensions.

[0062] Figure 3H provides an example of a cross-sectional view of a V-shaped feature. Figure 3H includes feature 301 to be filled with molybdenum, including a feature hole 305 in a substrate 303. The hole has a dimension near the opening (e.g., an opening diameter or a line width w, which may be between about 10 nm and about 20 nm, or about 15 nm). The width is measured by the distance between sidewalls of a feature. The width may vary from the top of the feature at the feature opening (the opening diameter or line width w) to the bottom of the feature.Attorney Docket No.: LAM1P104WO-12234-1WO The feature hole 305 is characterized in part by an axis 318. The V-shaped feature 301 includes a depth 360 which may be betw een about 80 nm and about 120 nm, or about 100 nm. In various embodiments, the sidewalls meet at a point 395 at the bottom of the feature or in some embodiments, the bottom of the feature plateaus to a flat bottom surface, which may have a distance from one sidewall to the other of between about O.lw and about 0.9w, or as a percentage of line width w at the opening of about 10% of the width w to about 90% of the width w. Other profiles in which the feature narrows from an opening to a closed end may benefit from the methods described herein, e.g., the closed end may have a curved surface. Still further, features having constrictions at a midpoint of the feature may also benefit from the methods described herein.

[0063] Features may have an aspect ratio of between 2: 1 and about 10: 1. or between about 6: 1 and about 8:1, or about 6: 1, or about 8:1. The pitch of the lines may be betw een about 5 nm and about 60 nm, or 20 nm and 60 nm, or between 10 nm and 30 nm, or between. The bottom of the feature, w hich is characterized as the region in the bottom 50% to 70% of the depth of the feature, may have a width between sidewalls of between 0 nm and about 20 nm.

[0064] Figure 31 provides another example of a cross-sectional view of a V-shaped feature. A V-shaped feature as described herein refers to any feature having narrowing width from the top field level of the substrate to the bottom of the feature. The bottom may be flat, curved, or a point. In the case of a horizontal feature, the feature narrows from the opening to an interior position.)

[0065] Figure 31 includes feature 301 to be filled with a metal such as molybdenum, including a feature hole 305 in a substrate 303. The hole has a dimension w near the opening (e.g., an opening diameter or a line width), which may be between about 10 nm and about 20 nm, or about 15 nm. The bottom of the feature 396 has a width narrower than that of w. For example, the bottom of the feature 396 may have a width between 1% and 90% of the width w, or between 1% and 50%, or between 10% and 20% of the width w. While the sidewalls are depicted as straight in the examples of Figures 3H and I, it will be appreciated that the sidewalls may have roughness and / or be less than perfectly straight.

[0066] Multiple V-shaped features are present on a substrate in various disclosed embodiments, such as shown in Figure 2B. Multiple features on a substrate are defined as adjacent features having a distance no larger than betw een 5 nm and 60 nm of each other. In various embodiments, such multiple features may be all V-shaped features, which may have a shape such as depicted in Figure 3H or 31.

[0067] Figure 3 J shows an example of a 3D DRAM structure that may be filled using the method described herein. In the example shown, the features include an innermost surface 353, whichAttorney Docket No.: LAM1P104WO-12234-1WO may be a nitride, and dielectric sidewall surfaces 355. Example dimensions of the features are between about 10 nm and 20 nm width and between about 150 nm and 250 nm depth. In a 3D DRAM structure, there may be up to hundreds features to be filled. The main surface of substrate 356 can extend in the x and y directions, with Figure 3J oriented in the z-direction. In various embodiments, the feature may have an under-layer, such as a barrier layer or adhesion layer. Nonlimiting examples of under-layers include dielectric layers and conducting layers, e g., silicon oxides, silicon nitrides, silicon carbides, metal oxides, metal nitrides, metal carbides, metal silicides, and metal lay ers. Figure 3K shows an example of line bending that can occur in a 3D DRAM structure.

[0068] Examples of feature fill for horizontally-oriented and vertically-oriented features are described below. It should be noted that the examples are applicable to both horizontally-oriented and vertically-oriented features. Moreover, it should also be noted that in the description below, the term “lateral” may be used to refer to a direction generally orthogonal to the feature axis and the term “vertical” to refer to a direction generally along the feature axis.

[0069] Disclosed embodiments are suitable for reducing line bending. Line bending analysis may be performed by measuring the line width and roughness of the trenches filled with molybdenum or other metal. The line bending analysis involves imaging the metal at the top of the device opening with plan-view microscopy and measuring the metal width at multiple points on multiple lines. For each line, the line width is measured across 100 points. From each line, one then calculates the average line width and the variation of the line width, which may also be defined as roughness. The “line width mean” is the average of all the individual lines' average line width measured during analysis.

[0070] For line bending, two main metrics are defined as follows: (i) line-to-line (LTL) variation is the standard deviation of the average line widths, thereby capturing the variation of line width changes across different lines on the image, and (ii) line width roughness (LWR) is the average of line roughness (variation of line width within each line) from all the measured lines, thereby capturing the average line width variation within single lines. These two metrics, LTL and LWR are combined into single variation metric, o total, as determined by O=(OI2+O22)12. Furthermore, LTL and o total are normalized with respect to line width mean, described as LTL % and o total %.

[0071] In various embodiments, the methods result in substrates where total variance is less than about 5 nm, or less than about 1.5 nm, or in percentage, less than about 7.2%, where total variance percentage is calculated by normalizing total variance by the average line width.Attorney Docket No.: LAM1P104WO-12234-1WO

[0072] While the description below focuses on molybdenum feature fill, aspects of the disclosure may also be implemented in filling features with other materials. For example, feature fill using one or more techniques described herein may be used to fill features with other materials, including W, Co, and Ru. Further, it can be used to fill features with any material that undergoes grain growth in vapor deposition processes.

[0073] According to various embodiments, the methods described herein may involve one or more of the following techniques: deposition of a thinner, sparser liner layer; bulk deposition of molybdenum at different temperatures; lower H2 dose time during bulk deposition; incorporation of oxygen impurities during bulk deposition; and incorporation of nitrogen impurities during bulk deposition. These techniques may be applied to thermal deposition of molybdenum in features. According to various embodiments, line bending mitigation may involve one or more of the mechanisms described below.

[0074] In some embodiments, lower bulk deposition temperatures result in lower surface energy. With less energy inducing zipping, the zipping effect is mitigated with less line bending. In some embodiments, lower temperatures and / or lower H2 dose time results in lower thermal cycling and lower thermal stress. This is in turn reduces line bending. One possible mechanism is due to thermal stress resulting from temperature-induced expansion and contraction. Longer H2 dose times can create larger grains. This leads to large grain coalescence and stress anisotropy. Shorter H2 dose time can generate finer and more uniform grains, which distributes stress more homogeneously. Shorter H2 dose times can reduce temperature fluctuations that cause thermal expansion and contraction by limiting the reaction time.

[0075] In some embodiments, incorporating impurities such as oxygen and / or nitrogen as the wordlines close results in lower surface energy. This is turn reduces zipping and line bending. In some embodiments, a rougher morphology resulting from deposition of thin, sparse liner results in less zipping.

[0076] Figure 4 is a process flow diagram that shows operations in a method according to various embodiments that may be used to reduce line bending. The process begins in an operation 402 with providing a structure including adjacent features. The structure may be provided to a semiconductor processing tool. In some embodiments, the structure is already disposed within the tool from a previous processing operation and operation 402 involves maintaining the structure in the tool.

[0077] As described above, structure is a logic or memory structure on a semiconductor substrate. The substrate may be a silicon wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material, such as dielectric,Attorney Docket No.: LAM1P104WO-12234-1WO conducting, or semi-conducting material deposited thereon. The adjacent features may be formed in one or more of the above-described layers. For example, the feature may be formed at least partially in a dielectric layer. In some embodiments, a feature may have an aspect ratio of at least about 2:1, at least about 4:1, at least about 6:1, at least about 10:1, or higher. Features may be spaced apart on the substrate by a pitch between adjacent features of about 5 nm to 60 nm.

[0078] The features are defined at least in part by one or more sidewalls and are open at least one end. For some structures, they may be open at two ends, such as the wordline features of a 3D NAND structure shown in 3F and 3G. According to various embodiments, the features may also include a bottom or interior closed end, which may be flat, V-shaped, curved, etc. as described above. According to various embodiments, deposition may occur on one or more material types. For example, fill of wordline features of a 3D NAND structure can involve deposition on alumina or other dielectric sidewalls. Fill of 3D DRAM features can involve deposition on a nitride closed end surface and oxide sidewalls. Examples of surfaces include semiconducting surfaces such as bare silicon, silicon germanium (SiGe); dielectric surfaces including silicon oxide (SiC>2), aluminum oxide (AI2O3), and hafnium oxide (HfOx); and conductive surfaces including titanium nitride (TiN), titanium silicide nitride (TiSiN), tungsten (W), Mo, and other metals.

[0079] Next, in an operation 404, a conformal liner layer is formed in the feature. This is a Mo-containing liner layer. In some embodiments, it can be a pure Mo layer, a molybdenum oxide layer, a molybdenum oxynitride layer, or a molybdenum nitride layer. Formation of the conformal liner layer generally involves an atomic layer deposition (ALD) process using a molybdenum-containing precursor, also referred to as a Mo precursor. Mo precursors are described below and include molybdenum halides, molybdenum oxyhalides, and organometallic molybdenum precursors. The selection of the precursor can depend on the materials on which deposition occurs. Deposition directly on dielectric films such as aluminum oxide, for example, can involve using a molybdenum oxyhalide and a co-reactant such as ammonia (NH3) or hydrazine (N2H2). This can form a molybdenum oxynitride, a molybdenum oxide, or molybdenum nitride liner layer. For features that include different material types (e g., a conductive bottom surface and dielectric sidewalls) formation of conformal liner layer can involve a non-selective deposition technique as described further below. Examples of liner layer thickness can be 5-30A as deposited. Depending on the temperature, this may be about 5-50 ALD cycles for example. In some embodiments, operation 404 is not performed. For example, if an incoming feature includes a layer on which molybdenum can be deposited, the operation may be omitted.

[0080] Bulk molybdenum is deposited on the liner layer in an operation 406. During operation 406, the liner layer may be converted to an elemental molybdenum layer. This may also beAttorney Docket No.: LAM1P104WO-12234-1WO characterized as removing impurities, i.e.. any non-metal constituent. The liner layer may have greater impurities than the subsequently deposited Mo layer, but they are sufficiently removed such that the stack resistivity is the same or similar to a stack that does not include a nucleation or liner layer. The thickness will also decrease; for example, a 30A as-deposited film may contribute about 10A metal to the stack.

[0081] According to various embodiments, one or more of the following may be employed to facilitate conversion of the nucleation layer to an elemental metal film: depositing the bulk conductor at a higher temperature (e.g., 550°C) than liner layer is deposited and in-situ deposition of the bulk layer, such that the liner layer is not exposed to air or otherwise oxidized before bulk deposition. Mo oxychlorides in particular are relatively easy to convert to elemental metal. The resulting converted liner layer and pure metal layer may each be characterized as having fewer than 1% atomic impurities.

[0082] An atomic layer deposition (ALD) cycle may be used to deposit the bulk molybdenum as described further below. In some embodiments, a four-step ALD cycle including pulses of molybdenum precursor / purge / reducing agent / purge is used. Hydrogen (H2) may be used a reducing agent.

[0083] Operation 406 may be performed to deposit bulk Mo conformally in the features until the features reach a stage in which they close to closing. This stage may be determined based on deposition rates and feature sizes, for example. It may also be determined for a particular process and feature size by imaging features at various points during the process. The information obtained may be used for processing of subsequent substrates.

[0084] At an operation 408, the deposition process and / or process conditions are modified to reducing zipping. Operation 408 may be performed prior to any zipping or with only minimal zipping occurring.

[0085] According to various embodiments, operation 408 may involve one or more of the following:• Changing a substrate temperature;• Introducing an ALD cycle that includes an oxidizing or inhibiting agent;• Changing the relative amounts of molybdenum precursor and reducing agent during one or more ALD cycles:• Changing the concentration of molybdenum precursor in one or more ALD cycles• Varying chamber pressure within an ALD cycleAttorney Docket No.: LAM1P104WO-12234-1WO Each of these and additional examples are described further below. Operation 408 may be performed until the feature is closed.

[0086] At an operation 410, the deposition and / or process conditions are changed for subsequent bulk deposition. An overburden layer may be deposited in operation 410. This operation may be omitted in some embodiments. In some embodiments, operation 410 involves modifying the parameter or sequence modified in operation 408. For example, if substrate temperature is lowered in operation 408, the substrate temperature can be returned to its previous level or otherwise raised in operation 410. In the same or other examples, the number of operations and / or compounds introduced in an ALD sequence may be changed to match that in operation 406. In the same or other examples, chamber pressure may be modified, for example, to return to constant chamber pressure through the ALD process. In some embodiments, the aspect of the process (e.g., temperature, pressure, concentration of molybdenum precursor, number of operations in the ALD sequence, etc.) that is changed in operation 408 may be changed in operation 410 in a manner appropriate for overburden deposition.

[0087] Figure 5 is a process flow diagram that shows operations in a method that involves temperature control to reduce line bending. Operations 502 and 504 may be performed as described above with respect to operations 402 and 404 of Figure 4. As described therein, in some embodiments, operation 504 may be omitted.

[0088] In an operation 506, bulk Mo is deposited a first substrate temperature. This operation corresponds to operation 406 of Figure 4. Operation 506 may involve an ALD process including alternating pulses of a molybdenum precursor and a reducing agent or other co-reactant. These may or may not be separated by purges. Further, in some embodiments, there may be an additional chemistry included in the ALD processes as discussed further below. Operation 506 may proceed until the features near closure. At an operation 508, bulk deposition of Mo is performed at a different temperature than in operation 506. In some embodiments, this involves reducing the substrate temperature by at least 50°C, at least 75°C, at least 100°C, or at least 150°C. This can allow completing fill of the feature while lowering thermal stress such that it does not cause line bending.

[0089] In some embodiments, a method according to Figures 4 and / or 5 is performed in a multistation chamber with each station having an independent substrate temperature control, e.g., through temperature control of a pedestal or other substrate support. Such chambers facilitate temperature control throughout a process. Figure 6 shows a representation of a quad-station module including four stations: station 1, station 2, station 3, and station 4. According to various embodiments, multiple stations may perform bulk deposition.Attorney Docket No.: LAM1P104WO-12234-1WO

[0090] In some embodiments, liner deposition is performed on station 1. In some such embodiments, bulk deposition on station 2 converts the liner to pure molybdenum as described above in addition to depositing bulk molybdenum. Bulk deposition on station 3 is at lower temperature during fill closure to reduce line bending. Station 4 may be used for overburden deposition. Examples of temperatures include:Station 1 Station 2 Station 3 Station 4Liner Deposition High T bulk Low T bulk High T bulk deposition deposition depositionLiner Deposition High T bulk Low T bulk Low T bulk deposition deposition depositionLiner Deposition Low T bulk Low T bulk High T bulk deposition deposition depositionLiner Deposition Med T bulk Low T bulk High T bulk deposition deposition depositionLiner Deposition Low T bulk Low T bulk Low T bulk deposition deposition deposition

[0091] Temperature can depend on the particular application. In some embodiments, it can range from 250°C to 700°C. For 3D NAND wordline fill, the range may be from 450°C to 700°C, for example, with "Low T being 450°C to 550° and "High T being at least 600°C. ‘"Med T” is a temperature between “Low T” and “High T.” In other embodiments, the low, medium, and high temperatures may be outside of these ranges, with high temperature being higher than medium temperature and medium temperature higher than low temperature.

[0092] The temperature sequences described above are not limited to multi-station chambers and may be employed with other processing configurations including single-station chambers and multiple chambers.

[0093] Reducing the bulk deposition temperature during wordline or other feature closure can be critical to the reducing line bending. Below are results from four sequences of wordline fill, with line bending variance as normalized to sequence 1. Each sequence includes 3 temperatures representing bulk deposition on a liner, bulk deposition during closure, and overburden, respectively.Attorney Docket No.: LAM1P104WO-12234-1WO Sequence ID and type Sequence (°C) Line Bending variance - normalized1 - HHH 600 / 600 / 600 1.002 - HLH 600 / 560 / 600 0.393 - HLL 600 / 560 / 560 0.394 - LLL 560 / 560 / 560 0.565 - HLH 600 / 500 / 600 0.21

[0094] Reducing temperature during station 3 (wordline closure) is critical and without significant impact on fill and film composition. Comparison of sequence 2 and sequence 5 shows that the size of the decrease in temperature correlates with the decrease in line bending. At some point, further decrease in temperature may cease to be advantageous, resulting in no deposition or very slow deposition with only small line bending improvement. Notably, the HLL and HLH sequences have similar results but are both improved over the LLL sequence, indicating that a reduction in temperature prior to the overburden deposition and during feature fill is important.

[0095] Referring back to Figure 4, in some embodiments, operation 408 involves a different ALD process than used in operation 406. For example, operation 406 may use a4-step ALD cycle. Figure 7 shows an example of molybdenum deposition in features on a substrate by an atomic layer deposition (ALD) process. In the example of Figure 7, the substrate is exposed to a process gas including a moly bdenum-containing precursor in an operation 701. A purge operation is then performed in an operation 703. An adsorbed layer of molybdenum-containing precursor remains, with the gas phase precursor removed. The substrate is then exposed to a reactant in an operation 705. This is typically a reducing agent, e.g., hydrogen. In plasma processes using a direct plasma, the plasma is ignited during this operation. In plasma processes using a direct plasma, reactant includes plasma species (e.g., hydrogen radicals) generated remotely. The reactant reacts with the adsorbed precursor to form a layer of molybdenum. A purge operation is then performed in an operation 707. Operations 701-707 may then be repeated until the molybdenum film is at a target thickness in an operation 709.

[0096] Modifications of the process described in Figure 7 can include exposure to the reactant as the first operation in each cycle, followed by a purge, exposure to the molybdenum-containing compound, and purge. Further modifications can include each cycle forming less than a monolayer. This can be performed by limiting the amount of one or both reactants. In some embodiments, the ALD process may not be strictly self-limiting. For example, one or both of theAttorney Docket No.: LAM1P104WO-12234-1WO 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. Further modifications can include repeating operation 701 (with or without an intervening purge) prior to performing operation 705 within a cycle. In some embodiments, operation 705 is repeated one or more times within a cycle. Such modifications facilitate diffusion through a feature. A process as described with respect to Figure 7 may be used to perform operation 406 of Figure 4.

[0097] The film composition and / or morphology may be modified in operation 408 of Figure 4 by one or more of the following modifications to a process as in Figure 7. In some embodiments, a different chemistry is added as an additional step in one or more cycles: Mo precursor / purge / H2 / purge / different chemistry / purge. For example, an impurity is introduced to the molybdenum film as the feature closes. This can be oxygen and / or nitrogen in some embodiments. Other impurities that may be incorporated include carbon, silicon, boron, and germanium. In some embodiments, introducing an impurity7involves introducing a chemistry including the impurity' to be added as part of the ALD process. For example, in some embodiments, oxidizing or nitriding agents are added to introduce oxygen or nitrogen:• Mo precursor / purge / Fb / purge / oxidizing agent / purge• Mo precursor / purge / Fh / purge / nitriding agent / purge

[0098] Examples of oxidizing agents include oxygen (O2), water (H2O), ozone (O3), and nitrous oxide (N2O). Examples of nitriding agents include ammonia (NEE), hydrazine (N2H2), nitrogen trifluoride (NF?), and nitrogen (N2). Boron may be similarly introduced as part of a 6-step cycle. Examples of boron-containing compounds include diborane (B2H6) and boron trichloride (BCE). Other chemistries may be similarly introduced as part of a six-step cycle. These include halogen-containing compounds such as NF3, BCI3, chlorine (CI2), fluorine (F2), and chlorine trifluoride (CIF3).

[0099] These can contribute to reduced line bending using these chemistries include reducing film surface energy by changing film composition. In addition to this mechanism, chemistries that can etch (such as the halogen-containmg compounds) can remove a portion of deposited film that sticks together that together to cause bending. Multiple cycles of six-step ALD cycle can then involve film deposition / etch / film deposition / etch cy cles.

[0100] Modifications of the 6-step cycle can include using a different reducing agent than H2, changing the order of the Mo precursor, reducing agent, and different chemistry' doses, and coflowing the different chemistry with one or both of the Mo precursor and reducing agent (either in addition to or instead of the dose of the different chemistry.) A 6-step cycle as described above may be used with or without temperature control as described above with respect to Figures 5 andAttorney Docket No.: LAM1P104WO-12234-1WO

[0101] In some embodiments, modifying the composition and / or morphology of the deposited film involves changing the concentration of the molybdenum precursor in the molybdenum precursor pulse. Molybdenum precursors are generally delivered with an inert carrier gas. Increasing a concentration in the carrier gas of an oxygen-containing molybdenum precursor such as MOO2CI2, for example, can result in an increase in oxygen incorporation. In some embodiments, transitioning from operation 406 to operation 408 in Figure 4 involves increasing the molybdenum concentration. Temperature may or may not be varied. Other related parameters may be varied, such as the relative amounts of molybdenum precursor and H2 or other reducing agents. This can be characterized as H2:Mo precursor partial pressure-dose time (e.g., Torr-second) ratio. In some embodiments, transitioning from operation 406 to operation 408 in Figure 4 involves decreasing this ratio. Decreasing the ratio and the relative amount of reducing agent to molybdenum precursor can result in a less pure film. In some embodiments, chamber pressure is varied within an ALD cycle to modulate the reducing agentMo precursor partial pressure-dose time.

[0102] The table below shows the significant reduction in line bending observed by reducing the H2 Torr-seconds from 270 to 180 for an ALD process.H2 Torr-seconds Line Bending variance - normalized270 1.00225 1.02180 .04

[0103] In some embodiments, chamber pressure is varied with an ALD cycle with low pressure used during the purges. During a pure ALD reaction, reactant A is adsorbed onto the surface substrate and the subsequent purge removes any non-adsorbed reactant A. During the reactant B dose, reactant B reacts with the adsorbed reactant B to form the metal. The subsequent purge then removes any remaining reactant B for the next deposition cycle. Incomplete purging results in unreacted reactant remaining in the process chamber, available to react with the other reactant in the next dose. In this manner, the deposition includes metal depositing at a higher deposition rate and with higher roughness. Low chamber pressure during purge can lead to incomplete purge and high roughness, reducing line bending. In addition to or instead of varying chamber pressure, incomplete purging can involve shortening the duration of each purge and / or using a purge in which an inert gas is flowed at a constant rate throughout the deposition. To reduce or eliminate a CVD component, a purge that uses one or more charge volumes may be used.Attorney Docket No.: LAM1P104WO-12234-1WO

[0104] Example 4-step ALD cycles are given below, with HP referring to high pressure and LP referring to low pressure.• LP reducing agent / LP Ar purge / HP Mo precursor / LP Ar purge• HP reducing agent / LP Ar purge / HP Mo precursor / LP Ar purgeAs with other ALD cycles described herein, the order of Mo precursor and reducing agent pulses may be varied. In some embodiments, transitioning from operation 406 to operation 408 of Figure 4 involves transitioning ALD cycles that have the same chamber pressure in each step to varied pressure cycles. Chamber pressures may range from 10 Torr to 90 Torr, e.g., 20 Torr to 60 Torr. Examples of high pressure may be between 45 Torr and 200 Torr with examples of low pressure between 5 Torr and 35 Torr. In some embodiments, high pressure is between 45 Torr and 60 Torr and low pressure is between 20 and 35 Torr.

[0105] The techniques described above may be used independently or together. For example, any of changing temperature, multi-chamber pressure, changing molybdenum precursor concentration, and changing reducing agentMo precursor Torr-second ratio can be implemented alone or another of these techniques, and may be used with ALD cycles of any number of steps.

[0106] In the same or other embodiments, the process may include an ALD “super-cycle.” In the context of this disclosure, an ALD super-cycle refers an ALD cycle that includes at least two cycles having different parameters. Figure 8 shows operations in a method of an ALD super-cycle, with specific examples used to mitigate line bending described below. In Figure 8, an ALD cycle is performed at a first set of parameters. A set of parameters can include: number of steps in the ALD cycle, identity of the pulse chemistries, amount of reactant delivered in a pulse (e.g., as measured by Torr-seconds), concentration of the reactant, chamber pressure at each pulse, whether the chamber pressure is uniform or variable within a cycle, and substrate temperature. This ALD cycle is performed x times, where x is an integer equal to or greater than 1. See operation 803.

[0107] Then, in an operation 805, an ALD cycle at a second set of parameters is performed. At least one parameter is changed such that the second set is different from the first. Operation 805 is performed y times, where x is an integer equal to or greater than 1. See operation 803.

[0108] Operations 801-807 described an ALD super-cycle. These operations may be performed n times in an operation 809. In some embodiments, a super-cycle may be used to perform operations 406 and 408 of Figure 4. In some embodiments, operation 408 can involve multiple super-cycles. In some embodiments, a super-cycle further includes one or more additional sets of ALD cycles using different parameters.

[0109] Examples of super-cycles are below. Mo refers to the molybdenum-containingAttorney Docket No.: LAM1P104WO-12234-1WO precursor.• Different chemistry super-cycle: ((Mo / Ar / H2 / Ar)x + (Mo / Ar / different chem / Ar)y)n • Multi-concentration super-cycle ((Low Mo% / Ar / H2 / Ar)x + (High Mo% / Ar / H2 / Ar)y)n • Multi-pressure super-cycle - (High pressure (Mo / Ar / H2 / Ar)x + Low pressure (Mo / Ar / H2 or different chem / Ar)y)n

[0110] In the multi-pressure super-cycle, the chamber pressure is changed from operation 801 to operation 805. In other embodiments, the chamber pressure may be changed within an operation 801 and / or 805 as described above.[OHl] In some embodiments, ammonia or other nitrogen-containing compound may be used to introduce nitrogen to the film. In some embodiments, an ALD cycle may employ ammonia or other nitrogen-containing reducing agent instead of hydrogen to form molybdenum oxynitride as the feature closes. A super-cycle may be used to alternate forming molybdenum oxynitride and forming elemental molybdenum layers to stack molybdenum oxynitride / molybdenum bilayers. Referring back to Figure 6, for example, station 1 may be used to deposit an initial molybdenum oxynitride liner layer, followed by a high temperature bulk deposition in station 2. Station 3 may be used for deposition of a molybdenum oxynitride liner layer and station 4 may be used for deposition of a high temperature molybdenum layer. The substrate may then be transferred back to station 1 for another molybdenum oxynitride deposition. The table below shows that increasing number of loops of molybdenum oxynitride and molybdenum deposition can significantly reduce line bending.Number of Mo oxide nitride / Mo Line Bending variance - loops normalized2 1.06 0.7410 0.66

[0112] In some embodiments, deposition of a liner layer may be preceded and / or succeeded by a hydrogen (H2) soak. An H2 soak can be continuous flow or pulsed with argon (Ar). The soaks may be used to prepare the surface for the subsequent liner or bulk deposition. Deposition may be at low or high pressure as described above, with the soak at the same pressure as the deposition. In embodiments in which multi-station chambers are used, the soak and liner deposition may be performed in the first station in some embodiments with bulk deposition in the subsequent stations.

[0113] While the examples described above refer mainly to thermal (non-plasma) methods,Attorney Docket No.: LAM1P104WO-12234-1WO plasma-based methods may also be employed to mitigate line bending. One aspect of the disclosure includes filling features with conformal film such that a seam is introduced. The seam prevents opposing surfaces from contact with each other. This in turn prevents zipping. Figure 9 shows a schematic diagram of feature fill with unmitigated thermal conformal ALD compared with plasma-enhanced ALD (PEALD) processes. In some embodiments. PEALD is employed to fill 2D DRAM structures with molybdenum. In particular embodiments, PEALD may be used to fill 2D DRAM structures in which molybdenum is deposited directly on a gate oxide layer. Figure 10 shows a comparison of feature fill of a 2D DRAM structure using thermal ALD (top) and PEALD (bottom). As can be seen, seam formation in the PEALD filled structure prevents zipping. In addition to PEALD, the thermal ALD techniques that mitigate line bending may also be used in 2D DRAM features for feature fill without line bending. For example, incorporating oxygen and nitrogen impurities before the wordline closure point with thermal ALD can be used to fill 2D DRAM features without line bending.

[0114] In certain embodiments, a multi-station chamber may be used to deposit a conformal layer of molybdenum on the gate oxide, followed by fill including seam formation, and an overburden layer. Figure 11 shows example operations in a multi-station chamber. The described operations may be alternately performed in a single-station chamber, in one or more stations of a multi-station chamber, or in separate chambers. In the example of Figure 11, a PEALD process is performed to deposit a molybdenum nucleation layer on the gate oxide in station 1. In station 2, a PEALD process is performed for conformal growth. In station 3, a seam is formed by the PEALD process. In the example of Figure 11, station 4 may be used for overburden deposition after the feature is filled.

[0115] The molybdenum precursor may be a molybdenum halide or molybdenum oxyhalide as described further below , including MOO2CI2, MoOCL, and MoCls. For deposition of elemental (pure) molybdenum, a reducing agent such as H2, B2H6, or SiEL may be used. Other co-reactants, including oxidizing agents and other reducing agents may be used, including co-reactants to form compound films (e.g., molybdenum oxides, molybdenum oxynitrides, etc.) or introduce impurities into the film. Examples of other co-reactants include NHs, N2H2, NFs, N2, H2O, Os, Ch, F2, CIFs, and BCE.

[0116] Returning to Figure 11 , a hydrogen-based plasma may be employed as the reducing agent in each station in some embodiments. Plasma-enhanced processes can allow formation of a pure Mo film on oxide without formation of a nitrogen or oxygen-containing film.

[0117] Purge operations may or may not be performed according to various embodiments. In some embodiments, a purge is performed only after the H2 plasma dose but not after the MoAttorney Docket No.: LAM1P104WO-12234-1WO precursor dose. In some embodiments, a purge is performed only after the Mo dose but not after the H2 plasma precursor dose. Single cycles of example processes are described below, the “ / ” indicated sequential doses.• 2-step no purge PEALD: H2 plasma / Mo precursor• 3-step PEALD: H2 plasma / Ar purge / Mo precursor• 3-step PEALD: H2 plasma / Mo precursor / Ar purge• 4-step PEALD: H2 plasma / Ar purge / Mo precursor / Ar purge

[0118] In some embodiments, a plasma-enhanced pulsed CVD process is performed for any of the operations. Examples include:• Separated Mo precursor doses + Continuous H2 plasma• H2 plasma / Mo precursor + Continuous Ar purge

[0119] The plasma may be a direct or remote plasma. In plasma processes using a direct plasma, the plasma is ignited in the station during the H2 dose. In plasma processes using a remote plasma, reactant includes plasma species (e.g., hydrogen radicals) generated remotely.

[0120] The plasma processes described above are advantageous for vertically-oriented features. The below table shows a comparison of line bending and void / seam space in a feature for conformal thermal ALD and conformal PEALD in a feature:Structure Line Bending - Normalized Void / Seam space - NormalizedIncoming (unfilled) 1 1Filled with thermal ALD 5 0.05Void / seam 1 0.2

[0121] Low temperatures during plasma processing may be employed to reduce thermal stress and mitigate line bending. In some embodiments, temperatures 500°C or lower, 450°C or lower, or 400°C or lower are used.Molybdenum Deposition

[0122] The methods described herein involve depositing molybdenum. Below is a description of molybdenum deposition methods that may be used in implementation of the above-described processes for mitigating line bending.

[0123] 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.Attorney Docket No.: LAM1P104WO-12234-1WO

[0124] In some embodiments, a Mo precursor is a molybdenum chloride (MoClx) compound also referred to as a molybdenum chloride precursor or MoClx precursor. Molybdenum chloride precursors are given by the formula MoClx, where x is 2, 3, 4, 5, or 6, and include molybdenum dichloride (M0CI2), molybdenum trichloride (MoCh), molybdenum tetrachloride (M0Q4), molybdenum pentachloride (MoCh), and molybdenum hexachloride (MoCls). In some embodiments, M0CI5 or Mode are used. While the description chiefly refers to MoClx precursors, in other embodiments, other molybdenum halide precursors may be used. Molybdenum halide precursors are given by the formula MoXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)) and z is 2, 3, 4, 5, or 6. Examples of MoXz precursors include molybdenum fluoride (MoFe). In some embodiments, a non-fluonne-containing MoXz precursor is used to prevent fluorine etch or incorporation. In some embodiments, a non-bromine-containing and / or a non-iodine-containing MoXzprecursor is used to prevent etch or bromine or iodine incorporation.

[0125] In some embodiments, the feature may be filled using a molybdenum oxyhalide precursor. Molybdenum oxyhalide precursors are given by the formula MoOyXz, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and y and z are numbers greater than 0 such that MoOyXz forms a stable compound. Examples of molybdenum oxyhalides include molybdenum dichloride dioxide (MOO2CI2), molybdenum tetrachloride oxide (MoOCh), molybdenum tetrafluoride oxide (M00F4), molybdenum dibromide dioxide (MoChBn), and the molybdenum iodides 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.

[0126] A molybdenum precursor may be provided in a carrier gas, e g., Ar in some embodiments. As an example, M0O2O2 may be provide as 10%(vol) in a process gas with the balance being argon. Reference to partial pressure of the precursor in this document refer to the precursor only, and not the carrier gas.

[0127] 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 (NEE), and hydrazine (N2H4). Ammonia and hydrazine may be used to deposit molybdenum nitrides or molybdenum oxynitrides.Attorney Docket No.: LAM1P104WO-12234-1WO

[0128] 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 Eh, 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.

[0129] 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.

[0130] 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'.

[0131] In some embodiments, the Mo precursor is a molybdenum fluoride (MoFx) compound, also referred to as a molybdenum fluoride precursor or MoFx precursor. Molybdenum fluoride precursors are given by the formula MoFx, where x is 4, 5. or 6, and include molybdenum tetrafluoride (MoF4), molybdenum pentafluoride (MoF5), and molybdenum hexafluoride (M0F6).

[0132] MoFe can be advantageous as it has a boiling point of 34°C. Being a gas at standard pressure and 35oC allows M0F6 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 M0F6 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 molarAttorney Docket No.: LAM1P104WO-12234-1WO 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 MoF6, 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.

[0133] Deposition using MoFe with H2 as reducing agent occurs only at unusually low concentration. As an example, for 0.5 seem of MoFe, atotal 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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., pulsesAttorney Docket No.: LAM1P104WO-12234-1WO of the hydrogen reactant. In some embodiments, a remote plasma may be used. The plasma may be remotely -generated or direct. Further it may be generated by any appropriate plasma generator including a capacitively-coupled plasma generator or an inductively-coupled plasma generator. A microwave plasma generator may be used.Apparatus

[0138] Any suitable chamber may be used to implement the disclosed embodiments. Example deposition apparatuses include various systems, e.g., ALTUS®, ALTUS® Max, ALTUS® LFW, and ALTUS® Max ICEFill, available from Lam Research Corp., of Fremont, California, or any of a variety of other commercially available processing systems. In some embodiments, a first layer may be deposited at a first station that is one of two, five, or even more deposition stations positioned within a single deposition chamber. Thus, for example, ammonia or hydrogen and a molybdenum precursor may be alternately introduced to the surface of the semiconductor substrate, at the first station, using an individual gas supply system that creates a localized atmosphere at the substrate surface to deposit a liner layer. The same or another station may be used for deposition of the subsequent conformal layer. That is, each of the layers may be deposited at its own individual station or two or more may be deposited at the same station. In embodiments in which the temperatures are different for deposition of different portions of the fill, for example, it can be advantageous to use two separate stations with individual temperature control. Two or more stations may be used to deposit metal in a parallel process. Alternatively, a wafer may be indexed to have deposition operations performed over two or more stations sequentially.

[0139] Figure 12 depicts a schematic illustration of an embodiment of an ALD process station 1200 having a process chamber 1202 for maintaining a low-pressure environment. In some embodiments, a plurality of ALD process stations may be included in a common low-pressure process tool environment. For example, Figures 13A and 13B depict embodiments of a multi-station and / or multi-chamber processing tool. In some embodiments, one or more hardware parameters of ALD process station 1200, including those discussed in detail below, may be adjusted programmatically by one or more computer controllers 1250. In some other embodiments, a process chamber may be a single station chamber.

[0140] ALD process station 1200 fluidly communicates with reactant delivery system 1201a for delivering process gases to a distribution showerhead 1206. Reactant delivery system 1201a includes a mixing vessel 1204 for blending and / or conditioning process gases, such as a Mo precursor-containing gas, a hydrogen-containing gas, an argon or other carrier gas, or other reactant-containing gas, for delivery to showerhead 1206. One or more mixing vessel inlet valves 1220 may control introduction of process gases to mixing vessel 1204. In various embodiments.Attorney Docket No.: LAM1P104WO-12234-1WO deposition of an initial Mo liner layer is performed in process station 1200 and in some embodiments, other operations such as in-situ clean or Mo gap fdl may be performed in the same or another station of a multi-station processing tool as further described below with respect to Figure 13 A.

[0141] As an example, the embodiment of Figure 12 includes a vaporization point 1203 for vaporizing liquid reactant to be supplied to the mixing vessel 1204. In some embodiments, vaporization point 1203 may be a heated vaporizer. In some embodiments, a liquid precursor or liquid reactant may be vaporized at a liquid injector (not shown). For example, a liquid injector may inject pulses of a liquid reactant into a carrier gas stream upstream of the mixing vessel 1204. In one embodiment, a liquid injector may vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another example, a liquid injector may atomize the liquid into dispersed microdroplets that are subsequently vaporized in a heated delivery pipe. Smaller droplets may vaporize faster than larger droplets, reducing a delay between liquid injection and complete vaporization. Faster vaporization may reduce a length of piping downstream from vaporization point 1203. In one scenario, a liquid injector may be mounted directly to mixing vessel 1204. In another scenario, a liquid injector may be mounted directly to showerhead 1206.

[0142] Reactant delivery system 1201a may also include one or more solid precursor delivery components including one or more on-board ampoules 1213 and / or bulk delivery components 1215. Figure 14 below7provides an example of a bulk delivery7system.

[0143] In some embodiments, a liquid flow7controller (LFC) upstream of vaporization point 1203 may be provided for controlling a mass flow of liquid for vaporization and delivery’ to process chamber 1202. For example, the LFC may include a thermal mass flow meter (MFM) located downstream of the LFC. A plunger valve of the LFC may then be adjusted responsive to feedback control signals provided by a proportional-integral-derivative (PID) controller in electrical communication w7ith 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.

[0144] Showerhead 1206 distributes process gases toward substrate 1212. In the embodiment shown in Figure 12, the substrate 1212 is located beneath showerhead 1206 and is shown resting on a pedestal 1208. Showerhead 1206 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to substrate 1212.

[0145] In some embodiments, pedestal 1208 may be raised or lowered to expose substrate 1212Attorney Docket No.: LAM1P104WO-12234-1WO to a volume between the substrate 1212 and the showerhead 1206. In some embodiments, pedestal 1208 may be temperature controlled via heater 1210. Pedestal 1208 may be set to any suitable temperature, such as between about 250°C and about 800°C during operations for performing various disclosed embodiments. It will be appreciated that, in some embodiments, pedestal height may be adjusted programmatically by a suitable computer controller 850. At the conclusion of a process phase, pedestal 1208 may be lowered during another substrate transfer phase to allow removal of substrate 1212 from pedestal 1208.

[0146] In some embodiments, a position of showerhead 1206 may be adjusted relative to pedestal 1208 to vary’ a volume between the substrate 1212 and the showerhead 1206. Further, it will be appreciated that a vertical position of pedestal 1208 and / or showerhead 1206 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 1208 may include a rotational axis for rotating an orientation of substrate 1212. It will be appreciated that, in some embodiments, one or more of these example adjustments may be performed programmatically by one or more suitable computer controllers 1250. The computer controller 1250 may include any of the features described below with respect to controller 1250 of Figure 12.

[0147] In some embodiments where plasma may be used as discussed above, showerhead 1206 and pedestal 1208 electrically communicate with a radio frequency (RF) power supply 1214 and matching network 1216 for powering a plasma. In some embodiments, the plasma energy may be controlled by controlling one or more of a process station pressure, a gas concentration, an RF source power, an RF source frequency, and a plasma power pulse timing. For example. RF power supply 1214 and matching network 1216 may be operated at any suitable power to form a plasma having a desired composition of radical species. Likewise, RF power supply 1214 may provide RF power of any suitable frequency. In some embodiments, RF power supply 1214 may be configured to control high- and low-frequency RF power sources independently of one another. Example low-frequency RF frequencies may include, but are not limited to, frequencies between 0 kHz and 900 kHz. Example high-frequency RF frequencies may include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz, or greater than about 13.56 MHz, or greater than 27 MHz, or greater than 80 MHz, or greater than 60 MHz. It will be appreciated that any suitable parameters may be modulated discretely or continuously to provide plasma energy for the surface reactions.

[0148] In some embodiments, the plasma may be monitored in-situ by one or more plasma monitors. In one scenario, plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, plasma density and / or process gas concentrationAttorney Docket No.: LAM1P104WO-12234-1WO 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.

[0149] In some embodiments, instructions for a controller 1250 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.

[0150] Further, in some embodiments, pressure control for process station 1200 may be provided by butterfly valve 1218. As show n in the embodiment of Figure 12, butterfly valve 1218 throttles a vacuum provided by a dow nstream vacuum pump (not show n). However, in some embodiments, pressure control of process station 1200 may also be adjusted by varying a flow rate of one or more gases introduced to the process station 1200.

[0151] Figure 13A and Figure 13B show examples of processing systems. Figure I3A shows an example of a processing system including multiple chambers. The system 1300 includes a transfer module 1303. The transfer module 1303 provides a clean, vacuum environment to minimize riskAttorney Docket No.: LAM1P104WO-12234-1WO of contamination of substrates being processed as they are moved between various modules. Mounted on the transfer module 1303 is a multi-station chamber 1309 capable of performing in-situ clean and / or ALD processes described above. Surface treatment and / or initial Mo layer deposition may be performed in the same or different station or chamber as the subsequent Mo gap fill.

[0152] Chamber 1309 may include multiple stations 1311, 1313, 1315, and 1317 that may sequentially perform operations in accordance with disclosed embodiments as descnbed above. In another example, the chamber 1309 may be configured to do parallel processing of substrates, with each station performing multiple processes sequentially.

[0153] 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 Mo in a first station at a first temperature followed by ALD of Mo at a second station at second temperature. Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0154] Also mounted on the transfer module 1303 may be one or more single or multi-station modules 1307. In some embodiments, a preclean as described above may be performed in a module 1307, after which the substrate is transferred under vacuum to another module (e.g., another module 1307 or chamber 1309) for ALD.

[0155] The system 1300 also includes one or more wafer source modules 1301, where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 1319 may first remove wafers from the source modules 1301 to loadlocks 1321. A wafer transfer device (generally a robot arm unit) in the transfer module 1303 moves the wafers from loadlocks 1321 to and among the modules mounted on the transfer module 1303.

[0156] Chamber 1309 may have one or more of the following features to enable single chamber 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.

[0157] Solid precursor delivery systems may include bulk delivery systems and / or on-board ampoules. Figure 14 below provides an examples of a solid precursor delivery system that may be employed.Attorney Docket No.: LAM1P104WO-12234-1WO

[0158] Figure 13B is an embodiment of a system 1300. The system 1300 in Figure 13B has wafer source modules 1301, a transfer module 1303, atmospheric transfer chamber 1319, and loadlocks 1321, as described above with reference to Figure 13A. The system in Figure 13B has three single station modules 1357a-1375c. The system 1300 may be configured to sequentially perform operations in accordance with disclosed embodiments. For example, the single station modules 1357a-1357c may be configured so that a first module 1357a performs deposition of a liner layer, a second module 1357b performs ALD of a Mo layer at a first temperature, and a third module 1357c performs ALD of Mo at a second temperature. In this example, anin-situ clean may be optionally performed in second module 1357b.

[0159] Stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate as described above with reference to Figure 12.

[0160] Returning to Figure 13A and 13B, in various embodiments, a system controller 1329 is employed to control process conditions during deposition. The controller 1329 will typically include one or more memory devices and one or more processors. A processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. Such a system controller may be employed in control of any of the processes and apparatus described herein.

[0161] The controller 1329 may control all the activities of the apparatus. The system controller 1329 executes system control software, including sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other parameters of a particular process. Other computer programs stored on memory' devices associated with the controller 1329 may be employed in some embodiments.

[0162] Typically, there will be a user interface associated with the controller 1329. The user interface may include a display screen, graphical software displays of the apparatus and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0163] System control logic may be configured in any suitable way. In general, the logic can be designed or configured in hardware and / or software. The instructions for controlling the drive circuitry may be hard coded or provided as software. The instructions may be provided by ■‘programming.’’ Such programming is understood to include logic of any form, including hard coded logic in digital signal processors, application-specific integrated circuits, and other devices which have specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general-purpose processor.Attorney Docket No.: LAM1P104WO-12234-1WO System control software may be coded in any suitable computer readable programming language.

[0164] 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.

[0165] 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.

[0166] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 1329. The signals for controlling the process are output on the analog and digital output connections of the deposition apparatus.

[0167] 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.

[0168] In some implementations, a controller 1329 is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc ). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller;’ which may control various components or subparts of the system or systems. The controller 1329, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.Attorney Docket No.: LAM1P104WO-12234-1WO

[0169] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may. in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0170] The controller 1329, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller 1329 may be in the ‘“cloud” or all or a part of a fab host computer system, which can allow for remote access of the w aler processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality' of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry' or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. The parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by including one or more discrete controllers that are networked together and w orking 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 w ith 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.

[0171] 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 orAttorney Docket No.: LAM1P104WO-12234-1WO 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.

[0172] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory. a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0173] The controller 1329 may include various programs. A substrate positioning program may include program code for controlling chamber components that are used to load the substrate onto a pedestal or chuck and to control the spacing betw een the substrate and other parts of the chamber such as a gas inlet. A substrate tilt and rotation program may include for tilt and rotation. A process gas control program may include code for controlling gas composition, flow7rates, 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 w afer chuck.

[0174] 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 w ith data from these sensors to maintain desired process conditions.

[0175] Figure 14 depicts an example precursor delix crx system according to various implementations. The precursor delivery system 1400. which may also be referred to herein as the system 1400. includes an ampoule 1402 that is configured to have a precursor 1404 (shown with cross-hatching) and heat that precursor 1404 to vaporize it and create a precursor vapor in the headspace 1406 of the ampoule 1402. The ampoule includes an inlet 1408 and an outlet 1410. The inlet 1408 is configured to receive inert gas from an inert gas source 1412. The inert gas and precursor vapor in the headspace of the ampoule form a mixture that is flowed out of the outlet 1410. In some implementations, like in Figure 14, the pressure in the ampoule 1402 may beAttorney Docket No.: LAM1P104WO-12234-1WO maintained or controlled by pressure flow control which may include a controller and / or flow control valve 1414, which in some implementations may be a throttle valve. As the mixture of inert gas and precursor vapor flows out of the outlet 1410, the pressure flow control of the ampoule flows inert gas into the ampoule 1402 through the inlet 1408 to maintain the pressure in the ampoule 1402. The ampoule also includes an inlet valve 1416 configured to control flow of the inert gas into the ampoule and an outlet valve 1418 configured to control flow out of the outlet 1410, as well as bypass valve 1420 through which the inert gas can flow downstream of the ampoule 1402 without flowing through the ampoule 1402.

[0176] The ampoule 1402 is located in one location of a fabrication facility, such as a “sub-fab,” that is different than the location of the semiconductor processing tool, and the processing modules, to where the mixture is flowed. For example, the semiconductor processing tool may be located on a fabrication floor that is a different level in the facility than where the ampoule is located. The different locations of the ampoule and semiconductor processing tool / processing modules is exemplified by the vertical dashed line.

[0177] The mixture of precursor vapor and inert gas is configured to flow out of the outlet 1410 and tow ards a plurality of flow7paths configured to flow the mixture to a plurality of processing modules and into a process volume of each processing module. These flow paths span from the location of the ampoule, e.g., in the sub-fab, to the separate location of the processing tools and / or modules, e.g., the fab floor. The system 1400 of Figure 14 includes four flow' paths 1422A-1422D that each span from the location of the ampoule on the left side of the dashed dividing line, e.g., the sub-fab, to a corresponding processing module 1424A-1424D on the right side of the dashed dividing line, e.g., on the fab floor. Each flow- path 1422A-1422D is configured to flow the mixture of precursor vapor and inert gas which includes having delivery conduits and other flow elements to contain and direct the flow' of mixture to the corresponding processing module 1424A-1424D. Each flow path is also configured to maintain the mixture at a temperature between about 100 C and 150 C which may include having heating elements that heat the delivery conduits of the flow path and / or thermal insulation around the delivery conduits. Each flow path also has a high-temperature mass flow' controller located at or near the corresponding processing module 1424A-1424D that is configured to control the flow' of the mixture along the flow' path. Although four flow paths and four processing modules are shown, the number of flow paths and processing modules may vary such that there are 2, 3, 4, 5, 6, 7, 8, or 10 processing modules and corresponding flow paths.

[0178] The foregoing describes implementation of disclosed embodiments in a single or multichamber semiconductor processing tool. The apparatus and process described herein may be usedAttorney Docket No.: LAM1P104WO-12234-1WO 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.

[0179] Implementation 1. A method comprising: providing a substrate having a plurality of features spaced apart, the features comprising sidewalls and one or more openings; depositing a molybdenum layer at a first set of deposition conditions, wherein the molybdenum layer grows from the sidewalls of each feature to a center of the feature; and as the molybdenum layer approaches the feature centers, changing the deposition conditions to a second set of deposition conditions to reduce interatomic force between molybdenum on opposing sidewalls of each feature.

[0180] Implementation 2. The method of implementation 1 , wherein each feature of the pl urality of features is a vertically -oriented feature having one opening and a feature bottom.

[0181] Implementation 3. The method of implementation 2, wherein each feature of the plurality7of features narrows from the opening to the feature bottom.

[0182] Implementation 4. The method of implementation 1 , wherein each feature of the plurality7of features is horizontally-oriented.

[0183] Implementation 5. The method of any of implementations 1-5, wherein the first set of deposition conditions has a first temperature, the second set of deposition conditions has a second temperature, wherein the second temperature is lower than the first temperature.

[0184] Implementation 6. The method of any of implementation 5, wherein the first set of deposition conditions has a first temperature, the second set of deposition conditions has a second temperature, wherein the second temperature is at least 50°C lower than the first temperature.

[0185] Implementation 7. The method of implementation 1, yvherein transitioning from the first set of deposition conditions to the second set of deposition conditions comprises lowering a substrate temperature, and wherein the method further comprises raising the temperature to depositAttorney Docket No.: LAM1P104WO-12234-1WO an overburden layer on the plurality of features.

[0186] Implementation 8. The method of any of implementations 1-5. wherein the first set of deposition conditions comprises a four-step atomic layer deposition (ALD) process and the second set of deposition conditions comprises a six-step ALD process.

[0187] Implementation 9. The method of implementation 8, wherein the four-step ALD process comprises alternating doses of a molybdenum-containing precursor and a reducing agent separated by purges and wherein the six-step ALD process comprises alternating doses the molybdenum-containing precursor, the reducing agent, and a third chemistry, separated by purges.

[0188] Implementation 10. The method of implementation 9, wherein the third chemistry is an oxidizing agent.

[0189] Implementation 11. The method of implementation 9, wherein the third chemistry is nitrogen-containing.

[0190] Implementation 12. The method of implementation 9, wherein the third chemistry is halogen-containing.

[0191] Implementation 13. The method of any of implementations 1-12, wherein depositing the molybdenum layer at the first set of deposition conditions comprises performing an ALD process at first chamber pressure and wherein changing the deposition conditions comprises lowering the chamber pressure relative to the first chamber pressure for one or more steps of the ALD process.

[0192] Implementation 14. The method of any of implementations 1-13, further comprising depositing a molybdenum-containing liner layer in the plurality of features including on the sidewalls, prior to depositing the molybdenum layer such that the molybdenum layer is deposited on the liner layer.

[0193] Implementation 15. The method of any of implementations 1-14, further comprising depositing additional layers such that a stack comprising a plurality of molybdenum and molybdenum oxynitride bilayers is deposited in the feature.

[0194] Implementation 16. A method comprising: providing a substrate having a plurality7of features spaced apart, the features comprising sidewalls and one or more openings; and depositing molybdenum within the plurality of features using an atomic layer deposition (ALD) process, wh erein the ALD process comprises a cycle comprising: a reducing agent dose and a molybdenum-containing precursor dose and wherein a chamber pressure of a chamber housing the substrate is lower during the reducing agent dose than during the molybdenum precursor dose.

[0195] Implementation 17. A method comprising: providing a substrate having a plurality7ofAttorney Docket No.: LAM1P104WO-12234-1WO vertically-oriented features spaced apart, the features comprising sidewalls and an opening; and reacting a molybdenum precursor with hydrogen plasma species to grow a molybdenum layer from the sidewalls of each feature to the feature center to thereby fill the features under conditions such that a seam is formed within each feature.

[0196] Implementation 18. The method of implementation 17, wherein the features are 2-D DRAM features and the molybdenum is deposited directly on a gate oxide layer.

[0197] Implementation 19. The method of implementation 17, further comprising depositing molybdenum on the filled features.

[0198] Implementation 20. The method of implementation 17, wherein the molybdenum precursor is reacted with hydrogen plasma species in a plasma-enhanced ALD process.

[0199] Implementation 21. The method of implementation 17, wherein the molybdenum precursor is reacted with hydrogen plasma species in a plasma-enhanced chemical vapor deposition (CVD) process.

[0200] Implementation 22. The method of any of implementations 17-21, wherein substrate temperature during grow th of the molybdenum layer is 500°C or less.CONCLUSION

[0201] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended sample claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

Attorney Docket No.: LAM1P104WO-12234-1WO CLAIMSWhat is claimed is:

1. A method comprising:providing a substrate having a plurality of features spaced apart, the features comprising sidewalls and one or more openings;depositing a molybdenum layer at a first set of deposition conditions, wherein the molybdenum layer grows from the sidewalls of each feature to a center of the feature; and as the molybdenum layer approaches the feature centers, changing the deposition conditions to a second set of deposition conditions to reduce interatomic force between molybdenum on opposing sidewalls of each feature.

2. The method of claim 1, wherein each feature of the plurality of features is a vertically-oriented feature having one opening and a feature bottom.

3. The method of claim 2, wherein each feature of the plurality of features narrows from the opening to the feature bottom.

4. The method of claim 1, wherein each feature of the plurality of features is horizontally-oriented.

5. The method of claim 1 , wherein the first set of deposition conditions has a first temperature, the second set of deposition conditions has a second temperature, wherein the second temperature is lower than the first temperature.

6. The method of claim 1 , wherein the first set of deposition conditions has a first temperature, the second set of deposition conditions has a second temperature, wherein the second temperature is at least 50°C lower than the first temperature.

7. The method of claim 1, wherein transitioning from the first set of deposition conditions to the second set of deposition conditions comprises lowering a substrate temperature, and wherein the method further comprises raising the temperature to deposit an overburden layer on the plurality of features.

8. The method of claim 1, wherein the first set of deposition conditions comprises a four-stepAttorney Docket No.: LAM1P104WO-12234-1WO atomic layer deposition (ALD) process and the second set of deposition conditions comprises a six-step ALD process.

9. The method of claim 8, wherein the four-step ALD process comprises alternating doses of a molybdenum-containing precursor and a reducing agent separated by purges and wherein the six-step ALD process comprises alternating doses the molybdenum-containing precursor, the reducing agent, and a third chemistry', separated by purges.

10. The method of claim 9. wherein the third chemistry is an oxidizing agent.

11. The method of claim 9, wherein the third chemistry is nitrogen-containing.

12. The method of claim 9. wherein the third chemistry is halogen-containing.

13. The method of claim 1, wherein depositing the molybdenum layer at the first set of deposition conditions comprises performing an ALD process at first chamber pressure and wherein changing the deposition conditions comprises lowering the chamber pressure relative to the first chamber pressure for one or more steps of the ALD process.

14. The method of claim 1 , further comprising depositing a molybdenum-containing liner layer in the plurality of features including on the sidewalls, prior to depositing the molybdenum layer such that the molybdenum layer is deposited on the liner layer.

15. The method of claim 1, further comprising depositing additional layers such that a stack comprising a plurality of molybdenum and molybdenum oxynitride bilayers is deposited in the feature.

16. A method comprising:providing a substrate having a plurality of features spaced apart, the features comprising sidewalls and one or more openings; anddepositing molybdenum within the plurality of features using an atomic layer deposition (ALD) process, wherein the ALD process comprises a cycle comprising: a reducing agent dose and a molybdenum-containing precursor dose and wherein a chamber pressure of a chamber housing the substrate is lower during the reducing agent dose than during the molybdenum precursor dose.Attorney Docket No.: LAM1P104WO-12234-1WO17. A method comprising:providing a substrate having a plurality of vertically-oriented features spaced apart, the features comprising sidewalls and an opening; andreacting a molybdenum precursor with hydrogen plasma species to grow a molybdenum layer from the sidewalls of each feature to the feature center to thereby fill the features under conditions such that a seam is formed within each feature.

18. The method of claim 17, wherein the features are 2-D DRAM features and the molybdenum is deposited directly on a gate oxide layer.

19. The method of claim 17, further comprising depositing molybdenum on the filled features.

20. The method of claim 17, wherein the molybdenum precursor is reacted with hydrogen plasma species in a plasma-enhanced ALD process.

21. The method of claim 17, wherein the molybdenum precursor is reacted with hydrogen plasma species in a plasma-enhanced chemical vapor deposition (CVD) process.

22. The method of claim 17, wherein substrate temperature during growth of the molybdenum layer is 500°C or less.

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