Feature filling with suppression

Abstract

Provided herein are methods of filling features with a metal, including inhibition of metal nucleation.

Description

Incorporation by reference

[0001] The PCT application form is filed simultaneously with this specification as part of this application. Each application identified in the PCT application form filed simultaneously, for which this application claims the benefit or priority thereof, is incorporated herein by reference in its entirety and for all purposes. Background Art

[0002] The deposition of metals in features is an integral part of many semiconductor manufacturing processes. These deposited metal films can be used for horizontal interconnects, vias between adjacent metal layers, and contacts between metal layers and devices. In an example of deposition, tungsten (W) layers can be deposited on titanium nitride (TiN) barrier layers using tungsten hexafluoride (WF6) by a chemical vapor deposition (CVD) process to form a TiN / W bilayer. However, as device scaling continues and more complex patterning schemes are adopted in the industry, the deposition of thin metal films has become a challenge. The continuous reduction in feature size and film thickness poses many challenges for filling features with void-free films. Deposition in complex high aspect ratio structures is particularly challenging.

[0003] The background description provided herein is for the purpose of generally presenting the background of the present disclosure. The work of the currently named inventors, to the extent described in this background art section and aspects of the specification that were not ascertainable as of the time of filing the application, is neither expressly nor impliedly admitted to be prior art against the present disclosure. Summary of the Invention

[0004] Methods for filling features with metals are provided herein, which include suppressing metal nucleation. One implementation aspect of the present disclosure relates to a method, which includes: a) providing a feature to be filled with metal to a processing station, the feature including a feature opening and sidewalls extending from the feature opening; and b) exposing the feature to a metal precursor, a reducing agent, and a nitrogen-containing gas to fill the feature with metal, wherein the nitrogen-containing gas suppresses metal deposition on the surface of the sidewalls it contacts.

[0005] In some embodiments, the flow rate of the nitrogen-containing gas is reduced as more metal is deposited in the feature.

[0006] In some embodiments, the method further includes: forming a liner of metal in the feature before (b).

[0007] In some embodiments, the method further includes: before (b), exposing the feature to the nitrogen-containing gas in the absence of significant deposition to suppress metal deposition near the feature opening.

[0008] In some embodiments, (b) comprises continuously co-flowing the metal precursor, the reducing agent, and the nitrogen-containing gas into the processing station.

[0009] In some such embodiments, the method further comprises: prior to (b), exposing the feature to the nitrogen-containing gas in the absence of significant deposition to inhibit deposition of the metal near the opening of the feature.

[0010] In some such embodiments, the flow rate of the reducing agent is ramped up and the flow rate of the nitrogen-containing gas is ramped down as (b) proceeds.

[0011] In some embodiments, (b) comprises continuously flowing the metal precursor into the processing station while pulse-delivering the reducing agent and the nitrogen-containing gas in an alternating sequence.

[0012] In some embodiments, (b) comprises continuously flowing the nitrogen-containing gas into the processing station containing the substrate while pulse-delivering the metal precursor and the reducing agent to the processing station.

[0013] In some embodiments, the metal precursor and the reducing agent are pulse-delivered together to the processing station.

[0014] In some embodiments, the pulses of the metal precursor and the pulses of the reducing agent are alternating.

[0015] In some embodiments, (b) comprises continuously flowing the reducing agent into the processing station containing the substrate while pulse-delivering the metal precursor and the nitrogen-containing gas to the processing station.

[0016] In some embodiments, the metal precursor and the nitrogen-containing gas are pulse-delivered together to the processing station.

[0017] In some embodiments, the pulses of the metal precursor and the pulses of the nitrogen-containing gas are alternating.

[0018] In some embodiments, the metal is one of tungsten (W), molybdenum (Mo), ruthenium (Ru), or cobalt (Co).

[0019] In some embodiments, the nitrogen-containing gas is ammonia.

[0020] Another aspect of the present disclosure relates to an apparatus comprising: a processing station comprising a showerhead to direct gas to a substrate support; a controller configured to execute machine-readable instructions for filling a feature with metal, the instructions including instructions for: (a) causing a metal precursor, a reducing agent, and a nitrogen-containing gas to flow into the processing station to fill the feature with metal.

[0021] In some embodiments, the instructions for (a) cause the metal precursor, the reducing agent, and the nitrogen-containing gas to flow continuously and co-currently into the processing station.

[0022] In some embodiments, the instructions further include instructions for: prior to (a), causing the nitrogen-containing gas to flow without flowing the reducing agent to inhibit metal deposition near the opening of the feature.

[0023] In some embodiments, the instructions further include instructions for: as (a) proceeds, causing a ramped increase in the flow rate of the reducing agent and a ramped decrease in the flow rate of the nitrogen-containing gas.

[0024] These and other aspects of the disclosure are discussed further below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1A and 1B are schematic examples of material stacks including a conductive metal layer according to various embodiments.

[0026] Figures 2A - 2K are schematic examples of various structures in which a metal fill layer can be deposited according to the disclosed embodiments.

[0027] Figure 3A is a process flow diagram illustrating operations in filling a structure with metal according to various embodiments.

[0028] Figure 3B shows Figure 3A cross-sectional views of features at various stages according to an embodiment of the process in

[0029] Figure 4 shows a schematic cross-section of a feature at multiple stages of filling.

[0030] Figure 5 shows an example of a process flow diagram illustrating operations in a method of filling a feature with metal.

[0031] Figure 6 shows Figure 5 cross-sectional views of features at multiple stages according to an embodiment of the process in

[0032] Figure 7 and Figure 8 depict examples of multiple ramped flow curves.

[0033] Figures 9 to 11 shows a schematic diagram of an apparatus that can be used according to certain embodiments. Detailed Implementation Modes

[0034] 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 processing operations are not described in detail to avoid unnecessarily obscuring the disclosed embodiments. Although the disclosed embodiments will be described in conjunction with specific embodiments, it should be understood that it is not intended to limit the disclosed embodiments.

[0035] Provided herein is a method of filling features with metals such as tungsten (W), molybdenum (Mo), cobalt (Co), and ruthenium (Ru), which can be used in logic and memory applications. Figure 1A and 1B are schematic examples of material stacks including a conductive metal layer according to various embodiments. Figure 1A and 1B depict the order of materials in a specific stack and, as further described below with reference to Figures 2A to 2K can be used with any suitable architecture and application. In the example of Figure 1A , a conductive metal layer 108 is deposited on a substrate 102. The substrate 102 can be a silicon or other semiconductor wafer, such as a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, which includes a wafer having one or more layers of materials (such as dielectric materials, conductive materials, or semiconductor materials) deposited thereon. The method can also be applied to form metallization stack structures on other substrates such as glass, plastic, etc.

[0036] In Figure 1A , a dielectric layer 104 is on the substrate 102. The dielectric layer 104 can be directly deposited on the semiconductor (e.g., silicon (Si)) surface of the substrate 102, or any number of intermediate layers can be present. Examples of dielectric layers include doped and undoped silicon oxide (SiO2), silicon nitride, and aluminum oxide (Al2O3) layers, and specific examples include doped or undoped SiO2 layers and Al2O3 layers. Additionally, in Figure 1AIn [the structure], a diffusion barrier layer 106 is disposed between a conductive metal layer 108 and a dielectric layer 104. Examples of diffusion barrier layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten nitride (WN), and tungsten carbonitride (WCN). Further examples of diffusion barrier layers are multi-component molybdenum-containing films such as molybdenum nitride (MoN). The conductive metal layer 108 is the main conductor of the structure. In some embodiments, the conductive metal layer 108 may include multiple body layers deposited under different conditions. The conductive metal layer 108 may or may not include a nucleation layer. For example, the conductive metal layer 108 may include a W body layer deposited on a W nucleation layer. In some embodiments, a metal layer of one metal (e.g., Mo) may be deposited on a thin growth initiation layer of another metal (e.g., W).

[0037] Figure 1B Another example of a material stack is shown. In this example, the stack includes a substrate 102, a dielectric layer 104, and the conductive metal layer 108 is directly deposited on the dielectric layer 104 without an intermediate diffusion barrier layer. The conductive metal layer 108 is as described with respect to Figure 1A above.

[0038] Although Figure 1A and 1B show examples of metallization stacks, the methods and resulting stacks are not limited thereto. For example, in some embodiments, the conductive metal layer may be directly deposited on a Si or other semiconductor substrate with or without a nucleation layer or an initiation layer. Figure 1A and 1B Examples illustrating the material sequence in a particular stack are provided and can be used with any suitable architecture and application. Examples of different applications and architectures are further described below with respect to Figures 2A - 2J above.

[0039] The methods described herein are performed on a substrate (which may be accommodated in a chamber). The substrate may be a silicon or other semiconductor wafer, such as a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, which includes a wafer having one or more layers of material (e.g., dielectric, conductive, or semiconductive material) deposited thereon. These methods are not limited to semiconductor substrates and can be performed on filling any feature with a metal-containing material.

[0040] The substrate may have features such as vias or contact holes, which may be characterized by one or more of narrow and / or recessed openings, constrictions within the feature, and high aspect ratios. The features may be formed in one or more of the above layers. For example, the features may be at least partially formed in the dielectric layer. In some embodiments, the features 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. An example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate.

[0041] Figure 2A Disclosed is a schematic example of a DRAM architecture including a buried metal word line (bWL) 208 in a silicon substrate 202. The metal bWL is formed in a trench etched in the silicon substrate 202. The liner of the trench is a conformal barrier layer 206 and an insulating layer 204, and the insulating layer 204 is disposed between the conformal barrier layer 206 and the silicon substrate 202. In Figure 2A the example, the insulating layer 204 may be a gate oxide layer formed of a high-k dielectric material (such as silicon oxide or silicon nitride material). In some embodiments disclosed herein, the conformal barrier layer is TiN or a tungsten-containing layer. In some embodiments, one or both of the insulating layer 204 and the conformal barrier layer 206 are absent.

[0042] Figure 2A The bWL structure shown in

[0043] Figures 2B - 2H is an additional schematic example of various structures in which a metal fill layer may be deposited according to the disclosed embodiments. Figure 2B Shows a cross-sectional drawing example of a vertical feature 201 to be filled with metal. The feature may include a feature hole 205 in a substrate 203. The hole 205 or other features may have dimensions near the opening, such as an opening diameter or line width between about 10 nm and about 500 nm (e.g., between about 25 nm and about 300 nm). The feature hole 205 may be referred to as an unfilled feature or simply a feature. The feature 201 and any feature may be characterized in part by an axis 218 extending through the length of the feature, which has a vertical axis for vertically oriented features and a horizontal axis for horizontally oriented features.

[0044] In some embodiments, the feature is a word line feature in a 3-D NAND structure. For example, the substrate may include a word line structure having any number (e.g., 50 to 150) of word lines, which have at least a deep vertical channel. Another example is a trench in a substrate or layer. The feature may have any depth. In various embodiments, the feature may have an underlying layer, such as a barrier layer or an adhesion layer. Non-limiting examples of the underlying layer include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers.

[0045] Figure 2CAn example of a feature 201 with a concave profile is shown. The concave profile is a profile that narrows from the bottom, closed end, or interior of the feature towards the feature opening. According to various embodiments, the profile may taper and / or include a protrusion at the feature opening. Figure 2C An example of the latter is shown, where the underlying layer 213 forms a substrate for the sidewall or inner surface of the feature hole 205. The underlying layer 213 can be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of the underlying layer may include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers. In a particular embodiment, the underlying layer 213 can be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the underlying layer 213 is different from or does not include the metal of a metal conductive layer. In some embodiments, the underlying layer 213 is tungsten-free. In some embodiments, the underlying layer 213 is molybdenum-free. The underlying layer 213 forms a protrusion 215 such that the underlying layer 213 is thicker near the opening of the feature 201 than inside the feature 201.

[0046] In some embodiments, features with one or more constrictions within the feature can be filled. Figure 2D An example of a view of various filled features with constrictions is shown. Figure 2D Each example (a), (b), and (c) includes a constriction 209 at the midpoint within the feature. The width of the constriction 209 can be, for example, between about 15 nm and about 20 nm. The constriction can cause pinch off during the deposition of tungsten or molybdenum in the feature using conventional techniques, and before a portion of the feature is filled, the deposited metal will prevent further deposition through the constriction, resulting in voids in the feature. Example (b) further includes a pad / barrier protrusion 215 at the feature opening. Such a protrusion can also be a potential pinch point. Example (c) includes a constriction 212 that is further away from the field region than the protrusion 215 in example (b).

[0047] Horizontal features in, for example, 3-D memory structures can also be filled. Figure 2E An example of a horizontal feature 250 including a constriction 251 is shown. For example, the horizontal feature 250 can be a word line in a 3-D NAND (also referred to as vertical NAND or VNAND) structure. In some embodiments, the constriction may be due to the presence of pillars in the 3-D NAND or other structures. Figure 2F A cross-sectional side view of a 3-D NAND structure 210 (formed on a silicon substrate 202) is presented, which has VNAND stacks (left 225 and right 226), a central vertical structure 230, and a plurality of stacked horizontal features 220 having openings 222 on opposite sidewalls 240 of the central vertical structure 230. Note, Figure 2FShows two "stacks" of the illustrated 3-D NAND structure 210, which together form a "trench-like" central vertical structure 230. However, in some embodiments, there may be more than two "stacks" arranged in sequence and spatially parallel to each other, with the gaps between each adjacent pair of "stacks" forming the central vertical structure 230, as Figure 2F specifically shown in. In this embodiment, the horizontal feature 120 is a 3-D memory word line feature that can fluidly enter from the central vertical structure 230 through the opening 222. Although not explicitly indicated in the figure, Figure 2F the horizontal features 220 present in both of the 3-D NAND stacks 225 and 226 shown in (i.e., the left 3-D NAND stack 225 and the right 3-D NAND stack 226) can also enter from the other side (the leftmost and rightmost sides respectively) of the stack through a similar vertical structure formed by additional 3-D NAND stacks (not shown on the leftmost and rightmost sides). In other words, each 3-D NAND stack 225, 226 contains a stack of word line features that can fluidly enter from both sides of the 3-D NAND stack through the central vertical structure 1230. In the Figure 2F specific example schematically shown, each 3-D NAND stack contains 6 pairs of stacked word lines, but in other embodiments, the 3-D NAND memory layout can contain any number of vertically stacked word line pairs.

[0048] The word line features in the 3-D NAND stack are typically formed by depositing a stack of alternating silicon oxide and silicon nitride layers and then selectively removing the nitride layers, leaving a stack of oxide layers with gaps therebetween. These gaps are the word line features. Any number of word lines can be vertically stacked in such a 3-D NAND structure as long as there are available techniques for forming the word lines and any word line techniques that can be used to successfully accomplish (substantially) void-free filling of the vertical features. Thus, for example, a VNAND stack can include between 2 and 256 horizontal word line features, or between 8 and 128 horizontal word line features, or between 16 and 64 horizontal word line features, etc. (the listed ranges are understood to include the endpoints).

[0049] Figure 2G Shows a cross-sectional top view of the same 3-D NAND structure 210 shown in a side view of Figure 2F where the cross-section is taken through the horizontal portion 260 as shown by the horizontal dashed line in Figure 2F . Figure 2GThe cross-section shows several rows of columns 255, which are shown in FIG. 1F as extending vertically from the base of the semiconductor substrate 202 to the top of the 3-D NAND stack 210. In some embodiments, these columns 255 are made of polysilicon material and are structurally and functionally important for the 3-D NAND structure 210. In some embodiments, such polysilicon columns can be used as gate electrodes for the stacked memory cells formed within the columns. Figure 2G The top view shows that the columns 255 form constrictions within the openings 222 of the word line features 220, i.e., the fluid accessibility of the word line features 220 from the central vertical structure 230 via the openings 222 (as Figure 2G shown by the arrows in ) is inhibited by the columns 255. In some embodiments, the size of the horizontal gap between adjacent polysilicon columns is between about 1 nm and 20 nm. The reduced fluid accessibility increases the difficulty of uniformly filling the word line features 120 with a conductive metal film. In Figure 2H , 2I and 2J, the structure of the word line features 220 and the challenge of uniformly filling them with a conductive metal material due to the presence of the columns 255 are further shown.

[0050] Figure 2H displays a vertical cut through the 3-D NAND structure similar to that shown in Figure 2F , but here focuses on a single pair of word line features 220, and additionally schematically shows a filling process that results in the formation of voids 275 in the filled word line features 220. Figure 2I The voids 275 are also schematically shown, but in this figure are shown by a horizontal cut through the columns 255, similar to the horizontal cut shown in Figure 2G . Figure 2J shows the accumulation of metal (e.g., W or Mo) around the columns 255 at the constriction, which results in the pinching off of the opening 222 such that no additional W, Mo, or other metal can be deposited in the region of the voids 275. According to Figure 2H and 2I , it is evident that void-free filling depends on having a sufficient number of deposition precursors migrate downward through the vertical structure 230, through the opening 222, past the constricted columns 255, and into the farthest extent of the word line features 220 before the accumulation of metal around the columns 255 pinches off the opening 222 and prevents further precursor migration into the word line features 220. Similarly, Figure 2J shows a single word line feature 220 as viewed from an upper cross-section and shows how the general conformal deposition of metal begins to pinch off the interior of the word line feature 220 due to the fact that the larger width of the columns 255 serves to partially block and / or constrict and / or limit what would otherwise be an open path through the word line feature 220. (It should be noted that the example in Figure 2J can be understood asFigure 2I A 2D rendering of the 3D features of the pillar constriction structure shown in to illustrate the constriction that would be seen in a plan view rather than a cross-sectional view). The three-dimensional structure may require a longer and / or more focused exposure to the precursor to enable filling of the innermost and bottommost regions.

[0051] In some embodiments, the method involves depositing a first metal layer in a feature. The first metal layer can be a nucleation layer, a body layer, or a body layer deposited on a nucleation layer. It can be deposited by an ALD process to conformally serve as a liner for the feature. The first metal layer can be exposed to an inhibition treatment. In some embodiments, the inhibition treatment is preferably applied near the top of the feature such that subsequent deposition at the bottom of the feature is not inhibited or is inhibited to a lesser extent than near the top. This results in bottom-up filling.

[0052] The method can also be used to fill multiple adjacent features, such as DRAM bWL trenches. The filling process of DRAM bWL trenches can deform the trenches such that the final trench width and resistance Rs are significantly non-uniform. This phenomenon is called line bending. Figure 2K Shows unfilled (231) and filled (235) narrow asymmetric trench structures DRAM bWL, which exhibit line bending after filling. As shown, a plurality of features are depicted on a substrate. These features are spaced apart and, in some embodiments, the spacing between adjacent features is between about 20 nm and about 60 nm or between about 20 nm and 40 nm. The spacing is defined as the distance between the mid-axis of one feature and the mid-axis of an adjacent feature. As shown by feature 203, unfilled features can typically be V-shaped with sloped sidewalls, where the width of the feature narrows from the top of the feature to the bottom of the feature. The feature expands from the bottom of the feature to the top of the feature. A deposition sequence using inhibition can be used to mitigate line bending. These include inhibiting the entire depth of the feature.

[0053] Examples of filling features in the horizontal and vertical directions are described below. It should be noted that, in at least most cases, these examples apply to features in the horizontal or vertical direction. Additionally, it should be noted that in the following description, the terms "lateral" or "horizontal" can be used to refer to a direction generally orthogonal to the feature axis, and the term "vertical" can refer to a direction generally along the feature axis.

[0054] Embodiments of the methods described herein employ a plasma containing an oxygen species to modulate or remove nucleation inhibition. In some embodiments, they can be implemented as part of a deposition-inhibition-deposition (DID) sequence for feature filling.

[0055] Figure 3A is a process flow diagram illustrating the operation of filling a structure with metal according to various embodiments, andFigure 3B shows a cross-sectional schematic diagram of the characteristics of an embodiment according to the Figure 3A process in various stages.

[0056] In Figure 3B , at 300, unfilled feature 302 is shown in the pre-fill stage. Feature 302 can be formed in one or more layers on a semiconductor substrate and can optionally have one or more layers lining the sidewalls and / or bottom of feature 302. Turning to Figure 3A , in operation 301, a metal film is deposited in the feature. This operation can be referred to as Dep1. In many embodiments, operation 301 is a substantially conformal deposition that forms a liner on the exposed surfaces of the structure. For example, in a 3D NAND structure such as Figure 2F shown, the metal film lines the word line feature 220. According to various embodiments, an atomic layer deposition (ALD) process is used to deposit the metal film to achieve good conformality. In alternative embodiments, a chemical vapor deposition (CVD) process can be used. Further, the process can also be performed with any suitable metal deposition (including physical vapor deposition (PVD) or electroplating processes). In some embodiments, after operation 301, the feature is not closed but is left sufficiently open to allow further reaction gases to enter the feature during subsequent depositions.

[0057] In the ALD process, the feature is exposed to alternating pulses of reaction gases. In the example of tungsten deposition, tungsten-containing precursors such as tungsten hexafluoride (WF6), tungsten hexachloride (WCl6), tungsten pentachloride (WCl5), tungsten hexacarbonyl (W(CO)6), or tungsten-containing organometallic compounds can be used. In some embodiments, the pulses of the tungsten-containing precursor are pulsed with a reducing agent such as hydrogen (H2), diborane (B2H6), silane (SiH4), or germane (GeH4). In the CVD method, the wafer is simultaneously exposed to the reactant gases. Deposition chemicals for other films are provided below. In Figure 3B , at 310, feature 302 is shown after Dep1 for forming material layer 304 filled in feature 302.

[0058] Next, in Figure 3A , in operation 303, the deposited metal film is exposed to an inhibition treatment. This can be a conformal or non-conformal treatment. As used herein, a non-conformal treatment means that the treatment is preferentially performed at or near one or more openings of the feature rather than inside the feature. For a 3-D NAND structure, the treatment can be conformal in the vertical direction such that the bottom word line feature is treated to approximately the same extent as the top word line feature, while non-conformal means that the interior of the word line feature is not treated or is treated to a significantly lesser extent than the feature opening. A conformal treatment means that the entire feature is treated to approximately the same extent. Such a treatment can be performed to mitigate, for exampleFigure 2K Line bending of the features in

[0059] Inhibiting treatment Treats the feature surface to inhibit subsequent metal nucleation at the treated surface. It can involve one or more of the following: inhibiting the deposition of a film, reacting a plasma species with the Dep1 film to form a composite film (e.g., WN or Mo2N), and inhibiting species adsorption. During subsequent deposition operations, there is a nucleation delay at the inhibited portion of the underlying film relative to the non-inhibited or less inhibited portion (if any). Operation 303 can be a non-plasma treatment. In some embodiments, a plasma operation can be used in place of the plasma operation. If it is a non-plasma operation, it can be a simple heat or activated by some other energy such as UV.

[0060] For thermal inhibition treatment, nitrogen and hydrogen-containing compounds such as ammonia (NH3) can be used. Thermal inhibition treatment can involve flowing a metal precursor, however, there is no significant deposition. If there is any deposition, it may be, for example, a discontinuous monolayer or less than a monolayer.

[0061] In Figure 3B feature 302 after the inhibiting treatment is shown at 320. The inhibiting treatment is a treatment that has the effect of inhibiting subsequent deposition on the treated surface 306. Inhibition can be characterized by an inhibition depth and an inhibition gradient. For non-conformal inhibition, the inhibition varies with feature depth, such that the inhibition at the feature opening is greater than the inhibition at the feature bottom, and may only extend to a portion of the feature. In the example shown in Figure 3B the inhibition depth is approximately half of the full feature depth. Additionally, the inhibiting treatment is stronger at the top of the feature, as shown by the deeper dashed line inside the feature. As described above, in other embodiments, the inhibition can be uniform throughout the feature.

[0062] Return Figure 3A , after operation 303, a second metal layer is deposited in the feature in operation 305. The second deposition can be referred to as Dep2 and can be performed by an ALD or CVD process. To deposit into a 3-D NAND structure, an ALD process can be used to achieve good step coverage throughout the structure. The Dep2 operation is affected by the previous inhibiting operation. For example, if the feature opening is preferentially inhibited over the feature interior, deposition will preferentially occur in the feature interior. In another example, nitrogen on the surface where metal is deposited along the sidewalls of the feature can prevent metal-metal (e.g., tungsten-tungsten bonding), thereby reducing line bending.

[0063] In Figure 3BIn the example of , since deposition is inhibited near the feature opening, during the Dep2 stage shown at 330, the material is preferentially deposited at the bottom of the feature rather than at the feature opening or to a lesser extent at the feature opening. This can prevent the formation of voids and seams within the filled feature. Thus, during Dep2, the material 304 can be filled in a bottom-up filling manner rather than a conformal Dep1 filling manner. As the deposition continues, the inhibition can be removed such that deposition on the mildly processed surface may no longer be inhibited. This is shown at 330 where the processed surface 306 is smaller than before the Dep2 stage. In Figure 3B the example of , as Dep2 progresses, eventually the inhibition is overcome on all surfaces and the feature is completely filled with the material 304, as shown at 340. Although Figure 3B the DID process in shows a feature of preferential inhibition at the top of the feature, in some embodiments, the entire feature can be inhibited. For example, such a process can be used to prevent line bending. Returning to Figure 3A , in certain embodiments, operations 303 and 305 can be performed in parallel.

[0064] Embodiments of the method include inhibition and deposition operations that are simultaneous or in parallel. In certain embodiments, the parallel operations can be implemented as part of a DID sequence. In other embodiments, the parallel operations can be part of any process sequence that includes deposition and inhibition operations.

[0065] According to various embodiments, the method can be particularly beneficial for features having one or more constrictions away from the field region. Examples of these types of features are, for example, as discussed above with reference to Figure 2D . Turning to Figure 4 , for example, shows a feature at multiple stages of the DID process as described with reference to Figure 3B . At 400, the feature before filling is shown. At 410, the feature with a conformal layer of metal 404 having a lining feature is shown. At 420, the feature after the inhibition process is shown. In this example, the small circles represent the processed surface 406. The surface at and directly below the constriction 412 is not processed or is processed to a lesser extent than at the top of the feature. At 440, the feature after deposition to fill the feature with metal 404 is shown. However, in this example, the presence of the constriction 412 results in pores 408 in the filled feature.

[0066] Figure 4 The features shown in are examples of features having constrictions away from the field region. Significantly more complex features can be filled using the methods described herein, including those having multiple constrictions at different feature depths.

[0067] Figure 5A process flow diagram depicting multiple operations in a method of filling a feature with metal. In Figure 5 , the process begins with the deposition of a conformal metal layer in the feature. This can involve an ALD process to form, for example, a liner layer of metal in the feature. Thereafter, an optional suppression treatment is performed in operation 503. The suppression treatment is as discussed above and generally involves flowing a nitrogen-containing compound such as NH3. As further discussed below, in certain embodiments, operation 503 depends on how the subsequent filling is performed and is not optional. It is contemplated that operation 503 preferentially treats surfaces at or near the field region as discussed above. Thereafter, in operation 505, a parallel suppression and deposition process is performed. Parallel suppression and deposition refers to at least partial overlap of the suppression and deposition operations. In many embodiments, during part or all of a chemical vapor deposition (CVD) process, NH3 or other thermal suppression gas is co-flowed into the chamber with a metal precursor and a reducing agent.

[0068] Flowing a suppression gas during the filling process can increase the suppression depth. The flow rate and / or partial pressure of the suppression gas can be utilized to control the diffusion and depth of suppression, and the diffusion and depth of suppression can be changed during the course of operation 505. An example is shown in Figure 6 . In Figure 6 , at 620, a feature with a suppressed surface 606 is shown. The feature can be, for example, the feature when transported to a deposition station. Figure 6 In the example of , the suppression gas NH3 co-flows with WF6 and H2. The NH3 flow rate is sufficient such that NH3 diffuses slightly past the constriction 612. WF6 and H2 diffuse to the bottom of the feature where they react and deposit tungsten 604. This is shown at 630.

[0069] Once the tungsten 604 passes through the constriction 612, the NH3 flow rate is reduced such that NH3 is present at the top of the remaining unfilled portion of the feature, thereby allowing WF6 and H2 to deposit at the bottom of the remaining unfilled portion of the feature. NH3 suppresses deposition at the top of the feature. This is shown at 635. Thereafter, the NH3 flow rate is reduced to zero, thereby allowing complete filling of the feature as shown at 640.

[0070] Adding NH3 or other suppression gas during deposition enhances the selectivity of metal growth, thereby keeping the feature open longer and enabling bottom-up growth. There can be a sidewall component of growth in certain embodiments. After the initial suppression after Dep1, the suppression gas flow rate and / or partial pressure can be utilized to change the relationship between selectivity and depth.

[0071] Returning to reference Figure 5 , in certain embodiments, operations 503 and 505 are performed at the same station. The remaining NH3 in operation 503 can further assist in bottom-up filling.

[0072] As described above, in certain embodiments, operation 503 is optional. If operation 503 is not performed, the first stage of operation 505 can be used as an initial inhibition operation. This operation can involve a high metal precursor flow rate accompanied by an inhibition gas. The reductant flow rate can be the same as or lower than that in subsequent depositions.

[0073] The flow rate sequence can be changed during operation 505. In certain embodiments, for example, two gases can be flowed continuously into the station while a third gas is pulsed. In certain embodiments, while one gas is flowed continuously, the other two gases can be pulsed. Pulsed delivery generally refers to on / off, but can also be from a high flow rate to a low flow rate.

[0074] Table 1 below shows examples of parallel CVD-inhibition (PCI) processes that can be used to fill features with tungsten. These process examples are further described below. The sequences can be used for other metal precursors, reductants, and inhibition gases. Table 1 Parallel CVD-Inhibition Processes

[0075] The flow rates can deviate from those in Table 1 based on the specific apparatus used, substrate size, deposition rate, and other process parameters. The relative amounts of the different gases can be extrapolated to various embodiments. Note that the amount of NH3 or other inhibition gas is significantly lower than the amount of H2 or other reductant. Thus, metal is deposited rather than metal nitride during deposition.

[0076] Exemplary temperature ranges for the above processes are from 350 °C to 490 °C. This can vary for different reactants. Exemplary chamber pressure ranges are from 10 Torr to 90 Torr.

[0077] In many examples, the reactants are ramped down or up. This can be done in a stepwise or continuous manner and with or without a plateau region at each stage. An example of a ramp-down curve is shown in Figure 7 . The duration, slope, and flow rate changes of each stage can vary or remain constant from stage to stage. The ramp-up of the gas flow can similarly take various forms depending on the geometric features of the structure and the apparatus used.

[0078] In many examples, the flow is pulsed and puffing is involved. In this way, a pressurized pulse of the reactant or inhibition gas can be introduced into the chamber. The puffing volume is further described below. In addition to or instead of the flow rate, the diffusion depth can be adjusted by varying the puffing volume pressure.

[0079] Process 1 has a ramped-down continuous NH3 flow rate. A suppression process is performed prior to the PCI process. NH3 is flowed co-currently with WF6 and H2, but the NH3 is ramped down. Figure 6 and Figure 7 Examples of ramped-down flow rate profiles are shown in

[0080] Process 2 has a pulsed NH3 flow rate. Figure 8 Examples of ramped-down pulsed flows are shown in . As indicated above, a pressurized line or plenum may be used to deliver a pressurized pulse, and an adjusted pressure may be used to regulate the depth of suppression, in addition to or in lieu of the flow rate. Process 2 may reduce NH3 usage compared to Process 1 while maintaining the NH3 concentration in the feature. Like Process 1, Process 2 involves an initial suppression treatment in the absence of tungsten formation.

[0081] Process 3 is performed without an initial suppression treatment. PCI involves a ramped-down NH3, a ramped-up H2, and a constant WF6. A relatively low H2 at the start of the process provides an initial suppression effect. NH3 may be started at a higher volumetric flow rate compared to processes using an initial suppression.

[0082] Process 4 is performed using a constant WF6 and alternating NH3 and H2. In this way, the process can alternate from being suppression-favorable to deposition-favorable with as many cycles as possible of the feature. The NH3 may be ramped down throughout the process.

[0083] Process 5 is performed with an optional initial suppression. NH3 is flowed continuously with a pulsed WF6 + H2 co-current. The NH3 is ramped down as described above. In an alternative embodiment, an alternating pulse of WF6 and H2 may be used in lieu of the co-current. This may result in more ALD-type surface-mediated deposition.

[0084] Process 6 involves continuous H2 flow while pulsed WF6 + NH3 co-current. Flowing the H2 has a de-suppression effect, which can be beneficial for shaping the deposition profile. In an alternative embodiment, an alternating pulse of WF6 and NH3 may be used in lieu of the co-current.

[0085] In embodiments where an initial suppression is performed, for example, by flowing NH3 or other suppression gas with or without WF6 or other metal precursor (without a reducing agent), the process can transition from suppression to a PCI process without an intervening purge operation.

[0086] Co-current may involve synchronous pulses where valves allow the flow of each gas to be opened simultaneously or timed such that the gases arrive at the processing station or mixing chamber at the same time. Metal precursor

[0087] While WF6 is used as an example of a tungsten-containing precursor in the above description, other tungsten-containing precursors may be suitable for performing the disclosed embodiments. For example, metal-organic tungsten-containing precursors may be used. Organometallic precursors and fluorine-free precursors may also be used, such as MDNOW (methylcyclopentadienyl-dicarbonylnitrosyl-tungsten) and EDNOW (ethylcyclopentadienyl-dicarbonylnitrosyl-tungsten). Chlorine-containing tungsten precursors (WCl x ) may be used, such as tungsten pentachloride (WCl5) and tungsten hexachloride (WCl6).

[0088] To deposit molybdenum (Mo), molybdenum-containing precursors may be used, which include molybdenum hexafluoride (MoF6), molybdenum pentachloride (MoCl5), molybdenum dioxydichloride (MoO2Cl2), molybdenum oxychloride (MoOCl4), and molybdenum hexacarbonyl (Mo(CO)6).

[0089] To deposit ruthenium (Ru), Ru-precursors may be used. Examples of ruthenium precursors that can be used in oxidation reactions include (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl)Ru(0), (1-isopropyl-4-methylbenzyl)(1,3-cyclohexadienyl)Ru(0)), (2,3-dimethyl-1,3-butadienyl)Ru(0) tricarbonyl, (1,3-cyclohexadienyl)Ru(0) tricarbonyl, and (cyclopentadienyl)(ethyl)Ru(II) dicarbonyl. Examples of ruthenium precursors that react with non-oxidizing reactants are bis(5-methyl-2,4-hexanediketonato)Ru(II) dicarbonyl and bis(ethylcyclopentadienyl)Ru(II).

[0090] To deposit cobalt (Co), cobalt-containing precursors may be used, which include cyclopentadienylcobalt(I) dicarbonyl, cobalt carbonyl, various amidinato cobalt precursors, diazadienyl cobalt complexes, cobalt amidinate / guanidinate precursors, and combinations thereof.

[0091] The metal-containing precursors may be reacted with a reducing agent as described above. In some embodiments, H2 is used as a reducing agent for the deposition of the bulk layer to deposit a high-purity film. Nucleation layer deposition

[0092] In some implementations, the methods described herein involve depositing a nucleation layer before depositing the bulk layer. For example, in the Dep1 operation, depositing a conformal layer would involve depositing a nucleation layer, followed by ALD of a thin bulk layer.

[0093] A nucleation layer is typically a thin conformal layer that aids in the subsequent deposition of a bulk material thereon. For example, the nucleation layer can be deposited prior to any filling of features and / or at subsequent points during the filling of features (e.g., via interconnects) on the wafer surface. For example, in some implementations, the nucleation layer can be deposited after tungsten etching in a feature and prior to an initial tungsten deposition.

[0094] In certain implementations, a pulsed nucleation layer (PNL) technique is used to deposit the nucleation layer. In the PNL technique for depositing a tungsten nucleation layer, pulses of a reducing agent, an optional purge gas, and pulses of a tungsten-containing precursor are sequentially injected into a reaction chamber and purged from the reaction chamber. The process is repeated in a cyclic manner until a desired thickness is achieved. PNL broadly encompasses any cyclic process of sequentially adding reactants to react on a semiconductor substrate, which includes atomic layer deposition (ALD) techniques. The nucleation layer thickness can depend on the nucleation layer deposition method and the desired bulk deposition quality. Generally, the nucleation layer thickness is sufficient to support high-quality, uniform bulk deposition. Example ranges are

[0095] The methods described herein are not limited to a particular method of nucleation layer deposition, but include depositing a bulk film on a nucleation layer formed by any method including PNL, ALD, CVD, and physical vapor deposition (PVD). Additionally, in certain implementations, bulk tungsten can be deposited directly in a feature without using a nucleation layer. For example, in some implementations, the feature surface and / or an underlying layer that has been deposited supports bulk deposition. In some implementations, a bulk deposition process can be performed without using a nucleation layer.

[0096] In various implementations, nucleation layer deposition can involve exposure to metal precursors and reducing agents as described above. Examples of reducing agents can include boron-containing reducing agents (which include diborane (B2H6) and other boranes), silicon-containing reducing agents (which include silane (SiH4) and other silanes), hydrazine, and germane. In some implementations, pulses of a metal-containing species can be alternated with pulses of one or more reducing agents, such as S / W / S / W / B / W, etc., where W represents a tungsten-containing precursor, S represents a silicon-containing precursor, and B represents a boron-containing precursor. In some implementations, a separate reducing agent can be not used, e.g., the tungsten-containing precursor can undergo thermal decomposition or plasma-assisted decomposition. Bulk deposition

[0097] As described above, bulk deposition can be performed across the entire wafer. In some implementations, bulk deposition can occur via a CVD process, where a reducing agent and a metal-containing precursor flow into a deposition chamber to deposit a bulk fill layer in the features. Examples of PCI processes include CVD as described above. An inert carrier gas can be used to transport one or more reaction streams, which may or may not be premixed. Unlike PNL or ALD processes, this operation generally involves continuously flowing the reactants until the desired amount is deposited. In certain implementations, the CVD operation can occur in multiple stages, where multiple consecutive and simultaneous flow periods of the reactants are separated by periods of diversion of one or more reactant flows. An ALD process can also be used for bulk deposition, where a metal-containing precursor is alternated with a reducing agent such as H2. In some implementations, ALD can be used to deposit an initial bulk layer in a Dep1 process, and CVD is used to fill other features using a PCI process. In some implementations, ALD (with parallel inhibition) can be used for feature fill, and CVD is used for the capping layer. In some implementations, ALD with parallel inhibition can be used for all bulk layer depositions.

[0098] It should be understood that the metal films described herein can include a certain amount of other compounds, dopants, and / or impurities, such as nitrogen, carbon, oxygen, boron, phosphorus, sulfur, silicon, germanium, etc., depending on the specific precursors and processes used. The metal content in the film can be from 20% to 100% (atomic) metal. In many implementations, the film is metal-rich, having at least 50% (atomic) metal, or even at least about 60%, 75%, 90%, or 99% (atomic) metal. In some implementations, the film can be a mixture of a metal or elemental metal (e.g., W, Mo, Co, or Ru) and other metal-containing compounds (e.g., tungsten carbide (WC), tungsten nitride (WN), molybdenum nitride (MoN), etc.). CVD and ALD depositions of these materials can include using any suitable precursors as described above. Inhibiting metal nucleation

[0099] Plasma inhibition processes involve exposure to a plasma generated from a nitrogen-containing compound (e.g., N2). In some embodiments, the plasma power, chamber pressure, and / or process gas can be pulsed.

[0100] The above-described processes use thermal inhibition in many embodiments. Thermal inhibition processes generally involve exposing features to nitrogen-containing compounds such as ammonia (NH3) or hydrazine (N2H4) to non-conformally inhibit features near feature openings. In some embodiments, the thermal inhibition process is carried out in the temperature range of 250 °C to 450 °C. At these temperatures, exposure of previously formed tungsten or other layers to NH3 produces an inhibitory effect. Other potential inhibitory chemicals such as nitrogen (N2) and / or hydrogen (H2) can be used for thermal inhibition at higher temperatures (e.g., 900 °C). However, for many applications, these high temperatures are beyond the thermal budget. In addition to ammonia, other hydrogen-containing nitriding agents (e.g., hydrazine) can also be used at lower temperatures suitable for back-end-of-line (BEOL) applications. During thermal inhibition, the metal precursor can flow with the inhibitory gas or flow in an alternating pulse form with the gas. These other inhibitory gases can be used to replace NH3 in the above-described processes.

[0101] In addition to the above surfaces, nucleation can be inhibited on liner / barrier layer surfaces such as TiN and / or WN surfaces. Any chemical that passivates these surfaces can be used. Inhibitory chemicals can also be used to adjust the inhibition curve, where different ratios of active inhibitory substances are used. For example, for the inhibition of W surfaces, nitrogen may have a stronger inhibitory effect than hydrogen; adjustment of the ratio of N2 and H2 gases in the forming gas can be used to adjust the profile.

[0102] In certain implementations, the substrate can be heated or cooled prior to inhibition. A predetermined temperature of the substrate can be selected to induce a chemical reaction between the feature surface and the inhibitory substance and / or to facilitate the adsorption of the inhibitory substance, as well as to control the rate of the reaction or adsorption. For example, a temperature can be selected to have a high reaction rate so that more inhibition occurs near the gas source.

[0103] After inhibition, the inhibitory effect can be adjusted as described above. In the same or other embodiments, it can also be modulated by soaking it in a reducing agent or metal precursor, exposing it to a hydrogen-containing (H-) plasma, performing a thermal anneal, or exposing it to air, which can reduce the inhibitory effect. Apparatus

[0104] Any suitable chamber can be used to implement the disclosed embodiments. Exemplary deposition apparatuses include a variety of systems, such as and Max, which is available from Lam Research Corp. of Fremont, California, or any of a variety of other commercially available processing systems.

[0105] In some embodiments, the first deposition can be performed at a first station, which is one of two, five, or even more deposition stations located within a single deposition chamber. Thus, for example, hydrogen (H2) and tungsten hexafluoride (WF6) can be introduced in alternating pulses to the surface of the substrate at the first station using separate gas supply systems that create a local atmosphere at the surface of the semiconductor substrate. Another station can be used for inhibition processing + PCI. In some embodiments, the inhibition can be performed in a separate module.

[0106] Figure 9 is a schematic view of a processing system suitable for performing deposition processing according to an embodiment. System 900 includes a transfer module 903. The transfer module 903 provides a clean, pressurized environment to minimize the risk of contamination of the substrate being processed as it is moved between various reactor modules. According to various embodiments, a multi-station reactor 909 capable of performing ALD, CVD, and processes such as inhibition processing and de-inhibition processing is mounted on the transfer module 903. The multi-station reactor 909 includes a plurality of stations 911, 913, 915, and 917, which can perform operations sequentially or in parallel according to the disclosed embodiments. For example, the multi-station reactor 909 can be configured such that station 911 performs W, Mo, Co, or Ru nucleation layer deposition using a metal precursor and a boron- or silicon-containing reducing agent and then performs W, Mo, Co, or Ru bulk deposition (Dep1) of a conformal layer using H2 as a reducing agent in an ALD process, and station 913 performs an inhibition and PCI process using a metal precursor, H2, and NH3. Stations 915 and 917 can operate each process in parallel, respectively. In another example, station 911 can perform nucleation layer deposition, station 913 can perform bulk deposition of a conformal layer, station 915 can perform inhibition, and station 917 can perform PCI. Alternatively, both stations 915 and 917 can perform both inhibition and PCI (in parallel). A station can include a heated pedestal or substrate support, one or more gas inlets or showerheads or dispersion plates.

[0107] Returning to Figure 9 , also mounted on the transfer module 903 can be one or more single- or multi-station modules 907, which can perform plasma or chemical (non-plasma) pre-cleaning, plasma and non-plasma inhibition operations, other deposition operations, or etching operations. The module can also be used for a variety of processes to, for example, prepare the substrate for deposition processing. The system 900 also includes one or more wafer source modules 901, where wafers are stored before and after processing. An atmospheric manipulator (not shown) in the atmospheric transfer chamber 919 can first move the wafer from the source module 901 to the load lock 921. A wafer transfer device (usually a robotic arm unit) in the transfer module 903 moves the wafer from the load lock 921 to the modules mounted on the transfer module 903 and moves the wafer between these modules.

[0108] In various embodiments, a system controller 929 is employed to control process conditions during deposition. The controller 929 will generally include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, a stepper motor controller board, and the like.

[0109] The controller 929 may control the activities of all deposition apparatuses. The system controller 929 runs system control software that includes an instruction set for controlling timing, gas mixing, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power level, wafer chuck or pedestal position, and other parameters for a particular process. In some embodiments, other computer programs stored on a memory device associated with the controller 929 may be used.

[0110] Typically, there will be a user interface associated with the controller 929. The user interface may include a display screen, a graphical software display of the apparatus and / or processing conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, and the like.

[0111] The system control logic can be configured in any suitable manner. Generally, the logic may be designed or configured in hardware and / or software. 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 any form of logic that includes hard-coded logic in a digital signal processor, an application specific integrated circuit, and other devices having a specific algorithm implemented as hardware. Programming is also understood to include software or firmware instructions executable on a general purpose processor. The system control software may be encoded in any suitable computer-readable programming language.

[0112] Computer program code for controlling germanium-containing reductant pulses, hydrogen gas flow, and tungsten-containing precursor pulses in a process sequence, as well as other processes, may be written in any conventional computer-readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. The 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.

[0113] Controller parameters relate to process conditions such as, for example, process gas composition and flow rate, 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 input using the user interface.

[0114] Signals for monitoring the process can be provided through the analog and / or digital input connections of the system controller 929. Signals for controlling the process are output through the analog and digital output connectors of the deposition apparatus 900.

[0115] The system software can be designed or configured in many different ways. For example, multiple chamber component subroutines or control targets can be written to control the operation of the chamber components required to perform the deposition process according to the disclosed embodiments. Examples of programs or program segments for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0116] In some embodiments, the controller 929 is part of a system, which can be part of the above-described embodiments. Such systems include semiconductor processing apparatuses, which include one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems can be integrated with electronics to control the operation of these systems before, during, or after the processing of a semiconductor wafer or substrate. The electronics can be referred to as a "controller", which can control various components or sub-parts of one or more systems. Depending on the processing requirements and / or the type of system, the controller 929 can be programmed to control any of the processes disclosed in the present invention, including controlling the delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, RF (radio frequency) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, plasma pulse frequency settings, fluid delivery settings, position and operation settings, the loading and unloading of wafers into and out of the tool and other transfer tools and / or the transfer of a load lock connected to or interfacing with a particular system.

[0117] Broadly speaking, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. The integrated circuit can include a chip storing program instructions in the form of firmware, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions can be instructions delivered to the controller or system in various different settings (or program files), and different settings (or program files) define the operating parameters for performing a specific process on or for a semiconductor wafer. In some embodiments, the operating parameters can be part of a recipe defined by a process engineer to complete one or more processing steps in the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies on a wafer.

[0118] In some embodiments, the controller 929 can be part of or coupled to a computer that is integrated with, coupled to, or networked to the system or combinations thereof. For example, the controller 929 can be in the "cloud" or be all or part of the fab main computer system, which can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of manufacturing operations, examine the history of past manufacturing operations, examine trends or performance criteria of multiple manufacturing operations, to change parameters of the current process, set process steps to follow the current process or initiate a new process. In some embodiments, a remote computer (e.g., a server) can provide a process recipe to the system via a network, which can include a local network or the Internet. The remote computer can include a user interface that allows input or programming of parameters and / or settings, which are then transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify the parameters for each process step to be performed during one or more operations. It should be understood that these parameters can be specific to the type of process to be performed as well as the type of tool that the controller is configured to connect to or control. Thus, as described above, the controller can be distributed, for example, by including one or more discrete controllers that are connected together via a network and work towards a common goal (e.g., the processing and control described herein). An example of a distributed controller for these purposes would be one or more integrated circuits in the chamber that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer), which combine to control the process in the chamber.

[0119] Exemplary systems can include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (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 system that can be associated with or used in the preparation and / or manufacture of semiconductor wafers.

[0120] As described above, depending on the one or more process steps to be performed by the tool, the controller can communicate with one or more other tool circuits or modules, other tool components, combined tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the factory, a host, another controller, or tools used in material handling that transport a container of wafers between tool locations and / or load ports in a semiconductor manufacturing facility.

[0121] The controller 929 may include different programs. The substrate positioning program may include program code for controlling chamber components for loading a substrate onto a pedestal or chuck and for controlling the spacing between the substrate and other components of the chamber such as gas inlets and / or targets. The process gas control program may include code for controlling gas composition, flow rate, pulse time, and optionally for flowing gas into the chamber prior to deposition to stabilize the pressure in the chamber. The pressure control program may include code for controlling the pressure in the chamber by adjusting, for example, a throttle valve in the exhaust system in the chamber. The heater control program may include code for controlling the current to a heating unit for heating the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas such as helium to the wafer chuck.

[0122] Examples of chamber sensors that may be monitored during deposition include mass flow controllers, pressure sensors such as pressure gauges, and thermocouples located in the pedestal or chuck. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain the desired processing conditions.

[0123] Figure 10 A schematic diagram depicting an embodiment of a processing station 1000 having a processing chamber 1002 for maintaining a low-pressure environment is shown. In some embodiments, multiple processing stations may be included in a common low-pressure processing tool environment. For example, Figure 9 An embodiment of a multi-station reactor 909 is described. In some embodiments, one or more hardware parameters of the processing station 1000, including those discussed in detail below, may be adjusted in a programmed manner by one or more computer controllers 1050. In other embodiments, the processing chamber may be a single-station chamber.

[0124] The processing station 1000 is in fluid communication with a reactant delivery system 1001a for delivering process gas to a distribution showerhead 1006. The reactant delivery system 1001a includes a mixing vessel 1004 for mixing and / or conditioning process gas, such as a metal precursor gas, a hydrogen-containing gas, an inhibitor gas, argon or other carrier gas, or other reactant-containing gas, for delivery to the showerhead 1006. One or more mixing vessels 1020 may control the introduction of process gas into the mixing vessel 1004.

[0125] As an example, Figure 10Embodiments include a vaporization point 1003 for vaporizing liquid reactants to be supplied to a mixing vessel 1004. In some embodiments, the vaporization point 1003 can be a heated vaporizer. In some embodiments, the liquid precursor or liquid reactant can be vaporized at a liquid injector (not shown). For example, the liquid injector can inject pulses of the liquid reactant into a carrier gas stream upstream of the mixing vessel 1004. In one embodiment, the liquid injector can vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another example, the liquid injector can atomize the liquid into dispersed droplets that are then vaporized in a heated delivery tube. Smaller droplets can vaporize more quickly than larger droplets, thereby reducing the delay between liquid injection and completion of vaporization. Faster vaporization can reduce the length of the tubing downstream of the vaporization point 1003. In one scenario, the liquid injector can be mounted directly to the mixing vessel 1004. In another scenario, the liquid injector can be mounted directly to the showerhead 1006.

[0126] In some embodiments, a liquid flow controller (LFC) can be provided upstream of the vaporization point 1003 to control the mass flow rate of the liquid to be vaporized and delivered to the processing chamber 1002. For example, the LFC can include a thermal mass flow meter (MFM) located downstream of the LFC. The plunger valve of the LFC can then be adjusted in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, it can take one second or more to stabilize the liquid flow using feedback control. This can extend the time to dispense the liquid reactant. Thus, in some embodiments, the LFC can dynamically switch between a feedback control mode and a direct control mode. In some embodiments, this can be performed by disabling the sensing line and the PID controller of the LFC. According to various embodiments, one or more plenum volumes can be connected to a process gas supplier.

[0127] In certain embodiments, a station can be equipped with one or more plenum volumes. As described above, pulsed delivery of reactants or purge gases can involve plenum volumes. An exemplary apparatus is shown in Figure 11 where four gas sources (precursor, NH3 co-reactant, H2, and purge gas) are each connected to a plenum volume 1101. According to various embodiments, all or only a subset of these gas sources can be connected to the plenum volume. The plenum volume 1101 is used to establish a pressurized volume of gas that subsequently flows into the processing chamber. The gas from the plenum volume 1101 is pressurized (e.g., 300 Torr to 700 Torr) and enters the chamber via a showerhead 1106. A susceptor 1108 for supporting a wafer is also shown.

[0128] Returning to Figure 10 , the showerhead 1006 distributes process gas toward the substrate 1012. In Figure 10In the illustrated embodiment, substrate 1012 is located below showerhead 1006 and is shown disposed on pedestal 1008. Showerhead 1006 can have any suitable shape and can have any suitable number and arrangement of ports for distributing process gas to substrate 1012.

[0129] In some embodiments, pedestal 1008 can be raised or lowered to expose substrate 1012 to the volume between substrate 1012 and showerhead 1006. In some embodiments, pedestal 1008 can be temperature controlled by heater 1010. Pedestal 1008 can be set to any suitable temperature during operation for performing the various disclosed embodiments. It should be understood that in some embodiments, the pedestal height can be adjusted programmatically via a suitable computer controller 1050. At the end of the process stage, pedestal 1008 can be lowered during another substrate transfer stage to allow removal of substrate 1012 from pedestal 1008.

[0130] In some embodiments, the position of showerhead 1006 can be adjusted relative to pedestal 1008 to change the volume between substrate 1012 and showerhead 1006. Additionally, it should be understood that the vertical position of pedestal 1008 and / or showerhead 1006 can be changed by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 1008 can include a rotation axis for rotating the orientation of substrate 1012. In some embodiments, one or more of these exemplary adjustments can be performed programmatically by one or more suitable computer controllers 1050. Computer controller 1050 can include any of the features described hereinbelow with respect to Figure 10 controller 1050.

[0131] If plasma is used during deposition or inhibition, the showerhead 1006 and the pedestal 1008 are electrically connected to a radio frequency (RF) power source 1014 and a matching network 1016 to power the plasma. In some embodiments, the energy of the plasma can be controlled by controlling one or more of the process station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, the RF power source 1014 and the matching network 1016 can be operated at any suitable power to form a plasma having a desired radical species composition. Similarly, the RF power source 1014 can provide RF power at any appropriate frequency. In some embodiments, the RF power source 1014 can be configured to control a high-frequency RF power source and a low-frequency RF power source independently of each other. Exemplary low-frequency RF frequencies can include, but are not limited to, frequencies between 0 kHz and 900 kHz. Exemplary high-frequency RF frequencies can include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz, or frequencies greater than about 13.56 MHz, or greater than 27 MHz, or greater than 80 MHz, or greater than 60 MHz. It should be understood that any suitable parameters can be discretely or continuously adjusted to provide plasma energy for surface reactions.

[0132] In some embodiments, the plasma can be monitored in situ by one or more plasma monitors. In one scenario, the plasma power can be monitored by one or more voltage, current sensors (e.g., VI probes). In another case, the plasma density and / or process gas concentration can be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters can be adjusted programmatically based on measurements from such in situ plasma monitors. For example, the OES sensor can be used in a feedback loop to provide programmed control of the plasma power. It should be understood that in some embodiments, other monitors can be used to monitor the plasma and other process characteristics. Such monitors can include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure sensors.

[0133] In some embodiments, instructions for the controller 1050 can be provided via input / output control (IOC) sequencing instructions. In one example, instructions for setting the conditions of a process stage can be included in the corresponding recipe stage of a process recipe. In some cases, the process recipe stages can be sequenced such that all instructions for a process stage are executed concurrently with that process stage. In some embodiments, instructions for setting one or more reactor parameters can be included in a recipe stage. For example, a first recipe stage can include instructions for setting the flow rates of an inert gas and / or a reactive gas (e.g., a metal precursor), instructions for setting the flow rate of a carrier gas (e.g., argon), and a time delay instruction for the first recipe stage. A subsequent second recipe stage can include instructions for adjusting or stopping the flow rates of the inert gas and / or the reactive gas, instructions for adjusting the flow rate of the carrier gas or a purge gas, and a time delay instruction for the second recipe stage. A third recipe stage can include instructions for adjusting the flow rate of H2, instructions for adjusting the flow rate of the carrier gas or a purge gas, and a time delay instruction for the third recipe stage. A subsequent fourth recipe stage can include instructions for adjusting or stopping the flow rates of the inert gas and / or the reactant gas, instructions for adjusting the flow rate of the carrier gas or a purge gas, and a time delay instruction for the fourth recipe stage. It should be understood that within the scope of the present disclosure, these recipe stages can be further subdivided and / or repeated in any suitable manner.

[0134] In addition, in some embodiments, pressure control for the processing station 1000 can be provided by the butterfly valve 1018. As Figure 10 shown in the embodiment of, the butterfly valve 1018 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of the processing station 1000 can also be adjusted by changing the flow rates of one or more gases introduced into the processing station 1000.

[0135] The foregoing describes embodiments of the present invention implemented in a single-chamber or multi-chamber semiconductor processing tool. The apparatus and processes described herein can be used in conjunction with lithographic patterning tools or processes, for example, for fabricating or manufacturing semiconductor devices, displays, LEDs, photovoltaic panels, etc. Generally, although not necessarily, these tools / processes will be used or operated together in a common manufacturing facility. Lithographic patterning of a film typically includes some or all of the following steps, each step enabling multiple viable tools: (1) coating a photoresist on a workpiece, i.e., a substrate, using a spin coater or sprayer; (2) curing the photoresist using a hot plate or furnace or ultraviolet curing tool; (3) exposing the photoresist to visible light or ultraviolet light or X-rays using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist and thereby pattern it using a tool such as a wet bench; (5) transferring the resist pattern to the underlying film or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as a radio frequency or microwave plasma resist stripper.

[0136] Unless otherwise specified, ranges in this disclosure include endpoints. For example, between 25:75–75:25 includes 25:75 and 75:25. Conclusion

[0137] While the foregoing embodiments have been described in some detail for purposes of clear understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and devices of the embodiments of the present invention. Accordingly, the embodiments of the present invention should be regarded as illustrative rather than restrictive, and these embodiments are not limited to the details given herein.

Claims

1. A method, comprising: a) providing a feature to be filled with metal to a processing station, the feature including a feature opening and sidewalls extending from the feature opening; and b) exposing the feature to a metal precursor, a reducing agent, and a nitrogen-containing gas to fill the feature with metal, wherein the nitrogen-containing gas inhibits metal deposition on the surface of the sidewalls it contacts.

2. The method according to claim 1, wherein the flow rate of the nitrogen-containing gas is reduced as more metal is deposited in the feature.

3. The method according to claim 1, further comprising: forming a metal liner in the feature before (b).

4. The method according to claim 1, further comprising: before (b), exposing the feature to the nitrogen-containing gas in the absence of significant deposition to inhibit metal deposition near the feature opening.

5. The method according to claim 1, wherein (b) comprises continuously co-flowing the metal precursor, the reducing agent, and the nitrogen-containing gas into the processing station.

6. The method according to claim 5, further comprising: before (b), exposing the feature to the nitrogen-containing gas in the absence of significant deposition to inhibit metal deposition near the feature opening.

7. The method according to claim 4, wherein the flow rate of the reducing agent is ramped up and the flow rate of the nitrogen-containing gas is ramped down as (b) proceeds.

8. The method according to claim 1, wherein (b) comprises continuously flowing the metal precursor into the processing station while pulse-delivering the reducing agent and the nitrogen-containing gas in an alternating sequence.

9. The method according to claim 1, wherein (b) comprises continuously flowing the nitrogen-containing gas into the processing station housing the substrate while pulse-delivering the metal precursor and the reducing agent to the processing station.

10. The method according to claim 9, wherein the metal precursor and the reducing agent are pulse-delivered to the processing station together.

11. The method according to claim 9, wherein the pulses of the metal precursor and the pulses of the reducing agent are alternating.

12. The method according to claim 1, wherein (b) comprises continuously flowing the reducing agent into the processing station housing the substrate while pulse-delivering the metal precursor and the nitrogen-containing gas to the processing station.

13. The method according to claim 12, wherein the metal precursor and the nitrogen-containing gas are pulse-delivered to the processing station together.

14. The method according to claim 12, wherein the pulses of the metal precursor and the pulses of the nitrogen-containing gas are alternating.

15. The method according to claim 1, wherein the metal is one of tungsten (W), molybdenum (Mo), ruthenium (Ru), or cobalt (Co).

16. The method according to claim 1, wherein the nitrogen-containing gas is ammonia.

17. An apparatus, comprising: A processing station, comprising a showerhead to direct gases to a substrate support; A controller configured to execute machine-readable instructions for filling a feature with metal, the instructions including instructions for: (a) causing a metal precursor, a reducing agent, and a nitrogen-containing gas to flow into the processing station to fill the feature with metal.

18. The apparatus of claim 17, wherein the instructions for (a) cause the metal precursor, the reducing agent, and the nitrogen-containing gas to flow continuously and co-currently into the processing station.

19. The apparatus of claim 17, wherein the instructions further include instructions for: prior to (a), causing the nitrogen-containing gas to flow without causing the reducing agent to flow to inhibit metal deposition near the feature opening.

20. The apparatus of claim 15, wherein the instructions further include instructions for: as (a) proceeds, causing a ramped increase in the flow of the reducing agent and a ramped decrease in the flow of the nitrogen-containing gas.

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