Molybdenum metallization and fill techniques for logic and memory

Abstract

The present invention provides a method of depositing molybdenum in a feature and an associated apparatus, the method comprising: providing a substrate comprising molybdenum to be filled to a chamber, the feature having one or more openings; depositing a conformal thin film of molybdenum in the feature; non-conformally treating the conformal film to increase an etch rate, wherein the treatment preferentially acts on a portion of the conformal film proximate to the one or more openings relative to a portion of the conformal film farther from the one or more openings; etching the conformal film in a non-conformal manner; and depositing molybdenum within the feature.

Description

[0001] Cross-references to related applications The PCT application form is filed concurrently with this specification as part of this application. Each of the applications listed in PCT application form A, D, which claims a benefit or priority therefrom, is incorporated herein by reference in its entirety for all purposes. Background Technology

[0002] The deposition of conductive materials is an integral part of many semiconductor manufacturing processes. These materials can be used for horizontal interconnects, vias between adjacent metal layers, contacts between metal layers and devices, and as lines in memory devices.

[0003] The background description provided herein is for the purpose of presenting the general context of this disclosure. The work of the currently designated inventor, within the scope described in this background section and in aspects of the specification that could not be identified as prior art at the time of filing, neither expressly nor impliedly acknowledges that it is prior art to this disclosure. Summary of the Invention

[0004] Methods and related apparatus for depositing molybdenum in features are provided herein. In some embodiments, these methods include a single-chamber metallization process, which includes plasma and heat treatment and the use of various molybdenum precursors. Related apparatus is also provided.

[0005] One aspect of this disclosure relates to a method comprising: providing a feature to be filled with molybdenum, the feature including a metal-containing bottom and dielectric sidewalls; selectively depositing molybdenum on the metal-containing bottom to partially fill the feature, thereby leaving exposed dielectric sidewalls; depositing conformal molybdenum pads on the exposed dielectric sidewalls and the molybdenum; and filling the feature with molybdenum.

[0006] In some embodiments, these operations are performed in a single chamber. In some embodiments, the method further includes exposing the metal-containing substrate to a metal halide to remove oxides from the substrate before selectively depositing molybdenum on it. In some embodiments, the method further includes exposing the metal-containing substrate to a reducing plasma to remove oxides from the substrate before selectively depositing molybdenum on it. In some embodiments, the selective deposition of molybdenum on the metal-containing substrate includes thermal atomic layer deposition (ALD) using a molybdenum halide precursor. In some embodiments, the deposition of the conformal molybdenum pad includes thermal ALD or plasma-enhanced ALD processes using molybdenum oxyhalides.

[0007] In some embodiments, the deposition of the conformal molybdenum pad includes a plasma-enhanced ALD process using molybdenum oxyhalide. In some embodiments, the metal-containing substrate comprises titanium. In some embodiments, the metal-containing substrate comprises molybdenum. In some embodiments, the operation of filling the feature with molybdenum includes an integration process that includes etching molybdenum. In some embodiments, the operation of filling the feature with molybdenum includes an integration process that includes suppressing molybdenum deposition.

[0008] Another aspect of this disclosure relates to an apparatus comprising: a multi-station chamber, wherein each station includes: a substrate support configured to support a substrate; a nozzle configured to introduce gas into a volume above the substrate support; a plasma generator configured to generate plasma between the substrate support and the nozzle; and a controller having instructions for: introducing pulses of molybdenum halide and a reducing agent into a first station containing the substrate to selectively deposit molybdenum into a feature to be filled with molybdenum (the feature comprising a metal bottom and dielectric sidewalls), leaving exposed dielectric sidewalls; transferring the substrate to a second station; introducing pulses of molybdenum oxyhalide and a reducing agent, generating plasma during the pulse of the reducing agent to deposit a conformal liner within the feature; transferring the substrate to a third station; and introducing a molybdenum-containing precursor to continuously fill the feature.

[0009] Another aspect of this disclosure relates to a method comprising: providing a substrate to a chamber, the substrate including a feature to be filled with molybdenum, the feature having one or more openings; depositing a conformal film of molybdenum in the feature; nonconformally processing the conformal film to increase an etching rate, wherein the processing preferentially acts on portions of the conformal film closer to the one or more openings relative to portions of the conformal film farther away from the one or more openings; nonconformally etching the conformal film; and depositing molybdenum within the feature.

[0010] In some embodiments, the feature is a word line feature of a 3D NAND structure. In some embodiments, the word line feature has a first opening and a second opening, which are located at opposite ends of the feature.

[0011] In some embodiments, the first opening leads to a first vertical structure of the 3D NAND structure and the second opening leads to a second vertical structure, wherein fluid can enter the feature via the first and second vertical structures. In some embodiments, the feature is further defined by a contraction formed by pillars of the 3D NAND structure.

[0012] In some implementations, non-conformal processing of the conformal film to improve the etching rate includes oxidation or nitriding.

[0013] In some implementations, the method further includes processing the feature before and after nonconformally etching the conformal film.

[0014] In some embodiments, the method further includes nonconformally etching molybdenum after depositing molybdenum within the feature, wherein the molybdenum is preferentially etched in the vicinity of the one or more openings.

[0015] In some embodiments, the conformal film in which molybdenum is deposited comprises depositing a molybdenum-containing pad using a molybdenum precursor and ammonia. In some embodiments, the conformal film for depositing molybdenum further comprises depositing a conformal layer of molybdenum on the molybdenum-containing pad using a molybdenum precursor and hydrogen.

[0016] Another aspect of this disclosure relates to an apparatus comprising: a multi-station chamber, wherein each station comprises: a substrate support configured to support a substrate; a nozzle configured to introduce gas into a volume above the substrate support; a plasma generator configured to generate plasma between the substrate support and the nozzle; and a controller having instructions for: depositing a conformal film of molybdenum in a feature; non-conformally processing the conformal film to increase the etching rate, wherein the processing preferentially acts on portions of the conformal film closer to the one or more openings relative to portions of the conformal film farther from the one or more openings; non-conformally etching the conformal film; and depositing molybdenum within the feature.

[0017] These and other aspects of this disclosure are described in more detail below with reference to the accompanying drawings. Attached Figure Description

[0018] Figures 1A and 1B are schematic examples of material stacks including Mo layers according to various embodiments.

[0019] Figures 2A-2L are schematic examples of various structures in which molybdenum can be deposited according to the disclosed embodiments.

[0020] Figure 3 is a schematic diagram of the features that are filled to contact the underlying metal.

[0021] Figure 4 is a schematic diagram of the molybdenum-on-molybdenum integration scheme.

[0022] Figure 5 is a process flow diagram illustrating exemplary operations in the method of interconnect metallization.

[0023] Figure 6A shows a cross-sectional representation of the characteristics during various stages of the process in Figure 5.

[0024] Figure 6B shows an example of a subprocess that can be performed for single-chamber interconnect metallization.

[0025] Figure 6C-6G shows a schematic diagram of another example of single-chamber metallization.

[0026] Figure 7-9 is a timing diagram of an example of pulsed CVD process.

[0027] Figure 10A shows an example of molybdenum deposition via atomic layer deposition (ALD) process.

[0028] Figure 10B shows the nucleation delay of molybdenum deposition on various surfaces.

[0029] Figure 11 shows an example of a process using a molybdenum precursor concentration gradient to fill features.

[0030] Figure 12 shows examples of deposition-etch-deposition and deposition-inhibition-deposition processes on vertically oriented features.

[0031] Figure 13 is a flowchart illustrating a hybrid deposition and etching method according to certain disclosed embodiments.

[0032] Figure 14 is a process diagram showing the operation in the deposition-etch-deposition method for filling word line features of a 3D NAND structure.

[0033] Figure 15A shows several operations of the process in Figure 14.

[0034] Figure 15B shows an example of a subprocess that can be performed for single-chamber metallization, which includes a deposition-etch-deposition process.

[0035] Figure 16 illustrates a schematic diagram of the implementation scheme for the ALD process station.

[0036] Figures 17A and 17B show examples of semiconductor processing tools.

[0037] Figure 18 provides an example of a solid precursor delivery system. Detailed Implementation

[0038] In the following description, numerous specific details are set forth to provide a full understanding of the presented embodiments. The disclosed embodiments can be implemented without some or all of these specific details. In other examples, well-known process operations have not been described in detail to avoid unnecessarily obscuring the disclosed embodiments. While the disclosed embodiments are described in conjunction with specific implementations, it should be understood that this is not intended to limit the scope of the disclosed embodiments.

[0039] Throughout the disclosure, the subscripts “x” and “y” are used to denote numbers greater than 0 that form stable compounds. However, it should be noted that the absence of “x” or other subscripts (e.g., in titanium nitride (TiN) or titanium oxynitride (TiON)) does not imply a specific atomic ratio.

[0040] This article provides a method for filling features with molybdenum (Mo), which can be used in logic and memory applications. Mo films can be deposited in semiconductor substrate features such as vias and trenches. Mo films can be deposited onto line features, as liner layers, and / or filling features.

[0041] In some implementations, the method involves bottom-up deposition of Mo within a feature. Bottom-up deposition refers to growth that occurs primarily or entirely from the bottom of the feature relative to its sidewalls. Bottom-up deposition differs from filling a feature by nucleation and growth on all its surfaces. This results in conformal growth and can potentially lead to the formation of pores and / or seams within the feature. For example, pores may form when growth at the top of the feature may clamp the feature. Seams may form at the center of the feature when the film grows inward from the sidewalls. Bottom-up deposition avoids the formation of pores and seams within the feature during filling processes. The reference to bottom-up deposition can include inside-out deposition of horizontally oriented features, where growth proceeds from the interior of the feature outward.

[0042] Although primarily described using Mo as a substrate, the method can be used to deposit other metals, including W, Co, and Ru. For some applications, molybdenum offers several advantages over other metals such as cobalt (Co), ruthenium (Ru), and tungsten (W): (i) unobstructed and pad-free molybdenum film deposition is more feasible on oxides and nitrides compared to the deposition of cobalt, ruthenium, and tungsten; (ii) Mo exhibits better resistivity scaling than tungsten; (iii) at temperatures below 450°C, Mo is not expected to mix with underlying Co compared to Ru mixed with Co; and (iv) Mo is relatively easier to integrate into current W schemes compared to copper and ruthenium.

[0043] Figures 1A and 1B are schematic examples of material stacks including a Mo layer according to various embodiments. Figures 1A and 1B depict examples of material sequences for particular stacks and can be used with any suitable architecture and application, as further described below. Figure 1A shows a first material stack 111 characterized by a substrate 102 and a molybdenum layer 108 deposited thereon. The substrate 102 may be a silicon or other semiconductor wafer, such as a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material deposited thereon, such as dielectric, conductive, or semiconductor materials. In some embodiments, the substrate 102 may be or include silicon (Si) or silicon germanium (SiGe). This method can also be applied to forming metallized stack structures on other substrates such as glass, plastic, etc.

[0044] The stack 111 has a dielectric layer 104 on the substrate 102. The dielectric layer 104 may be deposited directly on the semiconductor surface (e.g., Si or SiGe surface) of the substrate 102, or may be any number of intermediate layers. For example, the substrate 102 may include any number of layers deposited on the semiconductor surface in various arrangements.

[0045] Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, specifically doped or undoped silicon nitride (SiN), silicon dioxide (SiO2), and aluminum oxide (Al2O3) layers. The stack 111 has a layer 106 disposed between a molybdenum layer 108 and a dielectric layer 104. Layer 106 can be, for example, a diffusion barrier layer and / or an adhesion layer. A diffusion barrier layer is a layer that prevents material from diffusing between layers. An adhesion layer is a layer that promotes adhesion of a layer to the underlying layer. Examples of diffusion barrier layers and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten (W), tungsten nitride (WN), and tungsten carbonitride (WCN). The molybdenum layer 108 is the primary conductor of this structure. In some embodiments, the molybdenum layer 108 may include multiple host layers deposited under different conditions. The molybdenum layer 108 may or may not include a molybdenum nucleation layer. In the example shown in FIG. 1A, the molybdenum layer 108 is deposited directly on layer 106. In other embodiments (not shown), the molybdenum layer 108 may be deposited on a separate layer, such as a growth initiation layer comprising another material, such as tungsten (W) or a W-containing growth initiation layer. The growth initiation layer may be used to promote the nucleation and growth of the molybdenum layer 108.

[0046] Figure 1B shows another example of the stack 121. In this example, the stack 121 includes a substrate 102, a dielectric layer 104, and a molybdenum layer 108 deposited directly on the dielectric layer 104 without an intervening diffusion barrier layer or adhesion layer. The molybdenum layer 108 is as described with reference to Figure 1A. By using molybdenum as the primary conductor, low resistivity films can be obtained. Examples of low resistivity films include films with resistivity less than 40 µOhm-cm at a thickness of 60 angstroms and films with resistivity less than 15 µOhm-cm at a thickness of 200 angstroms.

[0047] In some embodiments, the stack (not shown) may include a substrate, a conductive layer, and a molybdenum layer deposited on the conductive layer. As used herein, the conductive layer has a surface area of ​​at least 10 at room temperature. 4 Ω -1 -cm -1The conductive layer is a layer. Examples include molybdenum on a metal layer (e.g., a W layer or another Mo layer). In these embodiments, there is no dielectric layer between the molybdenum layer and the conductive layer. Similarly, the stack may include molybdenum deposited directly on a metal compound layer. Examples include molybdenum on a metal nitride layer (e.g., TiN, WN, or MoN). In some other embodiments of the stack (not shown), the stack may include a substrate and a molybdenum layer deposited directly on the substrate, including directly deposited on a semiconductor surface, a dielectric surface, or a conductive surface. Figures 1A and 1B show examples of material order in a particular stack and can be used with any suitable architecture and application, examples of which are further described below.

[0048] The methods described herein are performed on a substrate that can be contained in a chamber. The substrate may be a silicon or other semiconductor wafer, including wafers having one or more layers of material (e.g., dielectric, conductive, or semiconductor material) deposited thereon. The method is not limited to semiconductor substrates and can be performed to fill any feature with molybdenum.

[0049] The substrate may have features such as vias or contact holes, characterized by one or more narrow and / or recessed openings, feature taper, and high aspect ratio. Features may be formed in one or more layers within the aforementioned stack. For example, features may be at least partially formed in a dielectric layer. In some embodiments, features may have aspect ratios 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 layer on a semiconductor substrate.

[0050] Figure 2A depicts a schematic example of a DRAM architecture including a Mo buried word line (bWL) 208 in a silicon substrate 202. The Mo bWL is formed in a trench etched in the silicon substrate 202. The trench pads are a conformal barrier layer 206 and an insulating layer 204. The conformal barrier layer 206 is disposed between the insulating layer 204 and the silicon substrate 202. In this example, the insulating layer 204 may be a gate oxide layer formed of a high-k dielectric material (e.g., silicon oxide or silicon nitride). In some embodiments disclosed herein, the conformal barrier layer 206 is a TiN or a tungsten-containing layer, such as a WN or WCN layer. In some embodiments, a conformal tungsten-containing growth initiation layer (not shown) may be present between the conformal barrier layer 206 and the molybdenum bWL 208. Alternatively, the molybdenum bWL may be deposited directly on a TiN or other diffusion barrier layer. In some embodiments, one or both of layers 204 and 206 are absent.

[0051] The bWL structure shown in Figure 2A is an example of an architecture that includes a molybdenum-filled layer. During the fabrication of the bWL, molybdenum is deposited into a feature that can be defined by an etched recess in a silicon substrate 202, which is conformally laid down with layers 206 and / or 204 (if present).

[0052] Figures 2B-2H are additional schematic examples of various structures in which molybdenum can be deposited according to the disclosed embodiments. Figure 2B shows an example cross-sectional drawing of a vertical feature 201 to be filled with Mo. This feature may include a feature aperture 205 in a silicon substrate 202. The feature aperture 205 may have an underlying layer 203 lining the sidewalls or interior of the feature aperture 205 and may form an internal surface. The feature aperture 205 or other features may have dimensions close to the opening, such as an opening diameter or linewidth between about 10 nm and 500 nm (e.g., between about 25 nm and about 300 nm). The feature aperture 205 may be referred to as an unfilled feature or simply a feature. The vertical feature 201 and any other feature may be characterized in part by an axis 218 extending through the length of the feature, with vertically oriented features having a vertical axis and horizontally oriented features having a horizontal axis. The underlying layer 203 may be, for example, a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other suitable material. Non-limiting examples of the underlying layer may include a dielectric layer and a conductive layer. Examples of dielectric materials include oxides, such as SiO2 and Al2O3; nitrides, such as SiN; carbides, such as nitrogen-doped silicon carbide (NDC) and oxygen-doped silicon carbide (ODC); and low-k dielectrics, such as carbon-doped SiO2. In specific implementations, the underlying layer may be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum. In some embodiments, the underlying layer does not contain tungsten. In some embodiments, the underlying layer does not contain molybdenum.

[0053] In some embodiments, the feature is a word line feature in a 3D NAND structure. For example, the substrate may include a word line structure having any number of word lines (e.g., 50 to 450) with vertical channels at least 200 Å deep. Examples of word line features are further described below. Another example of a feature is a trench in a substrate or layer. The feature can be of 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.

[0054] Figure 2C illustrates an example of a vertical feature 201 with a concave profile. 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 gradually narrow at the feature opening and / or include an overhang. Figure 2C shows an example of the latter, where a lower layer 213 paves the sidewalls or inner surface of the feature aperture 205. Similar to Figure 2B, the lower layer 213 may be a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other suitable material. Non-limiting examples of the lower layer may include dielectric and conductive layers. The lower layer 213 forms overhangs 215 such that the lower layer 213 is thicker near the opening of the vertical feature 201 than inside the vertical feature 201.

[0055] In some embodiments, a feature with one or more contractions may be filled within the feature. Figure 2D shows examples of views of various filled features with contractions. Each of the examples (a), (b), and (c) in Figure 2D includes a contraction 209 at the midpoint within the feature. The width of the contraction 209 may, for example, be between about 15 nm and 20 nm. During the deposition of molybdenum in the feature using conventional techniques, the contraction may cause clamping because the deposited metal blocks further deposition through the contraction before that portion of the feature is filled, resulting in voids in the feature. Example (b) also includes a protrusion 215 (e.g., a pad / barrier overhang) at the feature opening. Such a protrusion may also be a potential clamping point. Example (c) includes a contraction 212 further away from the field area than the protrusion 215 in example (b).

[0056] Horizontal features, such as those in 3D memory structures, can also be filled. Figure 2E shows an example of a horizontal feature 250 including a contraction 251. For example, the horizontal feature 250 may be a word line in a 3D NAND (also known as a vertical NAND or VNAND) structure. In some embodiments, the contraction may be due to the presence of pillars or other structures in the 3D NAND. Figure 2F presents a cross-sectional side view of a 3D NAND structure 210 (formed on a silicon substrate 202) having 3D NAND stacks (left 225 and right 226), a central vertical structure 230, and multiple stacked horizontal word line features 220, with an opening 222 on the reverse sidewall 240 of the central vertical structure 230. Note that Figure 2F shows two “stacks” of the illustrated 3D NAND structure 210, which together form a “trench-like” central vertical structure 230. However, in certain embodiments, there may be two or more such stacks arranged sequentially and extending parallel to each other in space, with the gap between each pair of adjacent stacks forming a central vertical structure 230, as clearly shown in FIG2F. In this embodiment, the horizontal word line feature 220 is a 3D memory word line feature that can fluidly enter and exit from the central vertical structure 230 through the opening 222. Although not explicitly indicated in the figure, the horizontal word line feature 220 present in both 3D NAND stacks 225 and 226 shown in FIG2F (i.e., the left 3D NAND stack 225 and the right 3D NAND stack 226) can also enter and exit the stacks from the other side of these stacks (to the leftmost and rightmost sides, respectively, but not shown in the figure) through a similar vertical structure formed by additional 3D NAND stacks. Each 3D NAND stack 225, 226 contains a stack of word line features that can fluidly enter and exit from both sides of the 3D NAND stack through the central vertical structure 230. In the specific example schematically shown in Figure 2F, each 3D NAND stack contains 6 pairs of stacked word lines. However, 3D NAND memory layouts can contain any number of vertically stacked word line pairs.

[0057] Word line features in a 3D NAND stack can be formed by depositing alternating stacks of silicon oxide and silicon nitride layers, followed by selective removal of the nitride layers, leaving a stack of oxide layers with gaps between them. These gaps are the word line features. Any number of word lines can be vertically stacked in such a 3D NAND structure, provided that there are available techniques for forming them, and techniques for achieving (substantially) gap-free filling that can be used to successfully implement vertical features. Thus, for example, a VNAND stack can include between 2 and 512 horizontal word line features, between 2 and 256 horizontal word line features, between 8 and 128 horizontal word line features, or between 16 and 64 horizontal word line features, etc. (the listed ranges should be understood to include the listed endpoints).

[0058] Figure 2G presents a top cross-sectional view of the same 3D NAND structure 210 shown in the side view of Figure 2F, with the cross-section taken through the horizontal portion 260, as indicated by the horizontal dashed line in Figure 2F. The cross-section of Figure 2G shows several rows of pillars 255, which are shown in Figure 1F as extending vertically from the bottom of the substrate 202 to the top of the 3D NAND structure 210. In some embodiments, the pillars 255 are formed of polysilicon and are structurally and functionally significant for the 3D NAND structure 210. In some embodiments, such polysilicon pillars can be used as gate electrodes for stacked memory cells formed within the pillars. The top view of Figure 2G shows the pillars 255 forming a contraction in the opening 222 leading to the word line feature 220. Fluid accessibility of the word line feature 220 from the central vertical structure 230 via the opening 222 (indicated by the arrow in Figure 2G) is suppressed by the pillars 255. In some embodiments, the horizontal gap size between adjacent polysilicon pillars is between approximately 1 nm and 20 nm. This reduction in fluid permeability increases the difficulty of uniformly filling the word line features 220 with material. Figures 2H, 2I, and 2J further illustrate the structure of the word line features 220 and the challenge of uniformly filling them with molybdenum material due to the presence of pillars 255.

[0059] Figure 2H shows a vertical cross-section similar to that shown in Figure 2F for a 3D NAND structure, but here focuses on a single pair of word line features 220, and also schematically illustrates the filling process that leads to the formation of voids 275 located within the filled word line features 220. Figure 2I also schematically shows voids 275, but in this figure is shown through a horizontal cross-section through pillar 255, similar to the horizontal cross-section shown in Figure 2G. Figure 2J shows the accumulation of molybdenum material around pillar 255 forming the contraction, which causes the opening 222 to be clamped, so that no additional molybdenum material can be deposited in the region of void 275. As can be clearly seen from Figures 2H and 2I, void-free molybdenum filling depends on a sufficient amount of deposition precursor migrating downward through the central vertical structure 230, through the opening 222, across the contraction pillar 255 and into the farthest extent of the word line feature 220, causing the opening 222 to be clamped and preventing further migration of the precursor into the word line feature 220 before the cumulative deposition of molybdenum around pillar 255. Similarly, Figure 2J shows a single word line feature 220 as viewed from above in cross-section, and illustrates how the generally conformal deposition of molybdenum material begins to clamp the interior of word line feature 220 due to the fact that the large width of pillar 255 acts to partially block, and / or narrow, and / or compress the open path that would otherwise pass through word line feature 220. (It should be noted that the example in Figure 2J can be understood as a 2D representation of the 3D feature of the pillar contraction structure shown in Figure 2I, thus showing the contraction as seen in a plan view rather than a cross-sectional view.) Three-dimensional structures may require longer and / or more concentrated exposure to the precursor to allow the innermost and bottommost regions to be filled. Three-dimensional structures can be particularly challenging when using molybdenum halide and / or molybdenum halide precursors because they are easily etched and the longer and more concentrated exposure time allows for more etching as part of the structure.

[0060] Figures 2K and 2L show examples of asymmetric trench structure DRAM bWL. Some fill processes used for DRAM bWL trenches can deform the trenches, resulting in significant non-uniformity in the final trench width and resistance Rs. Figure 2K shows unfilled feature 261 and filled feature 265 exhibiting line bending after filling. In this example, the feature is a narrow asymmetric trench structure DRAM bWL. As shown, multiple features 283 are depicted on the substrate. These features 283 are spaced apart, and in some embodiments, adjacent features have a pitch between about 20 nm and about 60 nm or between about 20 nm and about 40 nm. The pitch is defined as the distance between the central axis of a feature and the central axis of an adjacent feature. Unfilled feature 261 may be generally V-shaped, as shown in feature 283, with sloping sidewalls, wherein the width of the feature narrows from the top to the bottom of the feature. These features widen from the bottom 273b of the feature to the top 273a of the feature. Line bending can be observed within filled feature 265 after some fill operations. In some embodiments, cohesive forces between the opposing surfaces of the trench pull the trench sides together, as indicated by arrow 267. This phenomenon is shown in Figure 2L and can be described as “zipping up” the feature. As feature 283 is filled, more force is applied from the central axis 299 of feature 283, causing the line to bend. For example, molybdenum can be deposited on the sidewalls of feature 283. The molybdenum 284a and 284b deposited on the sidewalls of feature 283 thus interact closely, with the molybdenum-molybdenum bond radius r being very small, thereby generating cohesive interatomic forces between the smooth growth surfaces of molybdenum and pulling the sidewalls together, thus causing the line to bend.

[0061] The following describes methods for filling features with molybdenum. The methods described herein include surface treatments and deposition operations that can be used to fill substrate features, such as those described above. As mentioned above, molybdenum offers several advantages over other metals. Examples of feature filling for horizontally oriented and vertically oriented features are described below. It should be noted that, at least in most cases, these examples apply to both horizontally and vertically oriented features. A horizontally oriented feature generally refers to a feature oriented such that its feature axis is parallel to a plane of the substrate surface. A vertically oriented feature generally refers to a feature oriented such that its feature axis is orthogonal to a plane of the substrate surface.

[0062] In some embodiments, a method for filling a feature is described, which includes exposing the feature to a metal halide, such as a molybdenum halide, prior to feature filling. The metal halide may be etched, deposited, and / or otherwise treated with material on the bottom and / or sidewalls of the feature.

[0063] In some embodiments, the method is used to fill a feature to contact the underlying metal. An example of such a feature is shown in Figure 3. At 301, an unfilled feature 312 is shown. The unfilled feature 312 is formed in an oxide layer 305 and will be filled with Mo to contact the underlying metal-containing layer 303. The unfilled feature 312 is defined by a sidewall surface 315 and a bottom surface 317. In some embodiments, the metal-containing layer may be, for example, an elemental metal or a metal silicide.

[0064] According to various embodiments, the sidewall surface 315 and the bottom surface 317 can be made of the same or different materials. In some embodiments, an oxide layer 305 may be exposed to form the sidewall surface 315. Similarly, an underlying metal-containing layer 303 may be exposed to form the bottom surface 317. In some embodiments, surface oxidation causes the bottom surface 317 to become a metal oxide. In some embodiments, a padding layer (not shown) may be formed on the featured sidewalls and / or bottom to form the sidewall surface 315 and / or the bottom surface 317. Examples of padding layers include TiN, WN, and WCN. In some embodiments, the padding layer may be a molybdenum-containing padding layer, such as a molybdenum nitride (MoN) layer.

[0065] In some embodiments, the sidewall surface 315 and the bottom surface 317 are different. In subsequent deposition operations, Mo can be deposited under conditions where it preferentially nucleates on the bottom surface 317. This can promote bottom-up filling and prevent the formation of pores.

[0066] Examples of the underlying metal and / or bottom surface include TiN, titanium aluminum carbide (TiAlC), Ti, W, Co, Mo, Ru, Cu, nickel (Ni), iridium (Ir), rhodium (Rh), tantalum (Ta), and tantalum nitride (TaN).

[0067] The method described in this paper addresses several challenges that arise as feature sizes decrease. For example, void-free gap filling becomes more challenging in small features due to deeper features, concave profiles near feature openings, and / or insufficient growth selectivity between the bottom metal surface and the sidewall dielectric surfaces. Smaller features can lead to more frequent pattern misalignments. An example of a misaligned feature is shown at 350, where the unfilled feature 312 is not centered above the underlying metal 303. Therefore, the bottom surface 317 comprises both metal and dielectric material.

[0068] In some implementations, the method can be used in a molybdenum-on-molybdenum integration scheme. Figure 4 shows an example of such an integration scheme. Layer 401 includes a dielectric 402 and Mo 403. An etch stop layer (ESL) 404 is disposed above layer 401. ESL 404 can be, for example, SiN. A dielectric layer 405 is deposited on ESL 404. The dielectric layer 405 is then patterned and etched, wherein the etching stops at ESL 404 (not shown). ESL 404 is then removed from feature 412, forming an unfilled feature 412.

[0069] A Mo-containing layer 410 can be formed on the surface of Mo 403 during a previous processing operation. The Mo-containing layer 410 is typically an amorphous layer. It is relatively thin, for example, about 0.5 nm to 3 nm. It may contain various impurities, such as oxygen, nitrogen, and / or other halogens. Although surface oxidation can be removed by hydrogen (H2) plasma, the Mo-containing layer 410 is generally resistant to H2 plasma. If left in the device, it may result in higher resistance at the interface between Mo 403 and the subsequently deposited Mo film. Surface treatment can be performed before Mo deposition in the feature. According to various embodiments, surface treatment involves exposure to molybdenum halide. In some embodiments, molybdenum halide is provided without co-reactants, and deposition does not occur. In some embodiments, molybdenum halide is provided together with co-reactants. A thin layer of Mo can be deposited.

[0070] In some embodiments, the feature includes a dielectric surface, such as a dielectric sidewall surface. Surface treatment can suppress growth on the dielectric surface, thereby enhancing selectivity during subsequent deposition on the conductive surface. In some embodiments, the provided feature includes a Mo-containing layer as described above. Surface treatment can remove this layer, resulting in a clean Mo surface for deposition and the formation of Mo-Mo interconnects.

[0071] Interconnect metallization Figure 5 is a process flow diagram illustrating exemplary operations in a method for interconnect metallization. The process begins at operation 501, where a feature with dielectric sidewalls and metal contacts is provided. The metal contacts may be located at the bottom of the feature, with the dielectric sidewalls extending from the feature opening to the metal contacts. The feature may be provided to a processing chamber. In some embodiments, one or more processing operations may be performed in the processing chamber to form the feature with dielectric sidewalls and metal contacts.

[0072] Examples of dielectric sidewalls include silicon-containing layers, such as oxides and nitrides. Examples of metal-containing contacts include metals and metal compound films. Metal-containing contacts are typically conductive, exhibiting at least 10⁴ Ω at room temperature. -1 -cm -1The conductivity. Examples include TiN, TiAlC, W, Co, Mo, Ru, Cu, Ni, Rh, Ir, Ta, Ti, and TiSi. x RuSi x NiPtSi x TiSiN, MoSi x CoSi x And TaN.

[0073] In some embodiments, a surface oxide is present on the metal-containing contact. Furthermore, in some embodiments, a layer containing other impurities is present on the metal-containing contact. An example is the amorphous Mo-containing layer described with reference to Figure 4.

[0074] In some embodiments, prior to operation 501, an etching operation is performed to remove a pad layer from at least the sidewalls of the feature. For example, the feature may include a TiN pad layer conformally coated on the bottom and sidewalls. Etching may be performed to remove the TiN layer from the sidewalls, exposing the dielectric material. The sidewall surfaces are then silicon oxide or other dielectric materials.

[0075] In operation 503, a pretreatment is performed. For example, operation 503 may remove surface oxides and / or etching residues. Examples of etching residues include fluorocarbons and hydrocarbon polymers. According to various embodiments, operation 503 involves exposure to molybdenum halide gases and / or plasma cleaning.

[0076] Plasma cleaning can be performed remotely or in situ. In some embodiments, operation 503 involves exposure to a reducing plasma, such as H2 plasma. In some embodiments, operation 503 treats the dielectric sidewalls. For example, it can remove organic materials and / or reduce oxygen in the dielectric sidewalls. This can improve the selectivity of subsequent Mo growth on the metal-containing surface relative to the sidewalls.

[0077] In some embodiments, cleaning involves exposure to a molybdenum halide gas, such as MoCl5. This may be a plasma-free operation. Plasma-free means an operation performed without activating plasma. Exposure to molybdenum halides can remove impurities from metal contacts. For example, in embodiments where the amorphous Mo-containing layer of Figure 4 described above is present, it can remove all or at least a portion of that layer. In the same or other embodiments, exposure to molybdenum halides inhibits nucleation on the dielectric sidewall surfaces.

[0078] In some implementations, molybdenum chloride compounds are used. Molybdenum-containing compounds are also referred to herein as Mo-containing precursors or Mo precursors. Molybdenum chloride is produced by the formula MoCl. xThe expression is given, where x is 2, 3, 4, 5, or 6, and includes molybdenum dichloride (MoCl2), molybdenum trichloride (MoCl3), molybdenum tetrachloride (MoCl4), molybdenum pentachloride (MoCl5), and molybdenum hexachloride (MoCl6). In some embodiments, MoCl5 or MoCl6 is used. Although the description is primarily about MoCl... x The compound is used, but in other embodiments, other molybdenum halides may be used. The molybdenum halide precursor is of the formula MoX. z Given, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and z is 2, 3, 4, 5, or 6. MoX z Examples of precursors include molybdenum fluoride (MoF6). In some embodiments, fluorine-free MoX is used. z Precursors are used to prevent fluorine etching or incorporation. In some embodiments, bromine-free and / or iodine-free MoX is used. z Precursors are used to prevent etching, or the incorporation of bromine or iodine.

[0079] In some embodiments, operation 503 involves exposure to a molybdenum halide compound in the absence of a co-reacting gas. In such embodiments, the molybdenum halide can be pulsed or continuously fed. For example, MoCl5 can be pulsed-fed with argon (Ar) or other inert gases for several cycles. Alternatively, continuously fed MoCl5 can be fed followed by Ar purging.

[0080] In some embodiments, operation 503 involves exposure to a molybdenum halide compound and a co-reactant gas to deposit Mo. The co-reactant is typically H2, but other reducing agents described below may also be used. In one exemplary sequence, MoCl5 pulses alternate with H2 pulses, with an intermediate purge gas pulse. In another example, MoCl5 pulses alternate with H2 pulses, without an intermediate purge gas pulse. In yet another example sequence, MoCl5 pulses alternate with H2 pulses, wherein in each cycle, a purge gas pulse immediately follows only one of the reactant gases. In yet another example sequence, MoCl5 flows together with H2. In a further example sequence, the co-flow reactants are introduced in a pulsed manner under alternating Ar pulses. In yet another example sequence, H2 gas may flow into the chamber, and continuously into the chamber while MoCl5 flows in intermittently. In any of these examples, another molybdenum halide and / or another inert gas may be used instead of MoCl5 and Ar, respectively. In some embodiments, a sequence with co-reactants may be employed when a metal other than Mo is located at the bottom of the feature. In such an implementation, a Mo surface layer can be formed to facilitate subsequent Mo growth. For example, if a W, Co, or Ru layer is located at the bottom of the feature, operation 503 can be used to form a thin Mo surface layer.

[0081] As a supplement to or alternative to any of the above operations, operation 503 may involve atomic layer cleaning using chlorine-based plasma, hydrogen fluoride (HF) vapor cleaning, ammonium fluoride (NH4F) cleaning, or treatment using other reducing agents. These operations can be used to reduce oxides from the feature surface.

[0082] The process continues in operation 505, selectively depositing a Mo prefill layer on the metal-containing contacts. The selective deposition occurs on the metal-containing layer without significant deposition on the dielectric sidewalls.

[0083] In some embodiments, the operation involves a reaction using a molybdenum halide or molybdenum oxyhalide precursor. In some embodiments, MoCl5 is used because of its good selectivity, as described below.

[0084] Process conditions such as precursor gas, reducing agent, substrate temperature, process pressure, and exposure time can affect the selectivity of deposited Mo films. Different precursor gases may have different process windows, allowing for selective Mo film deposition. For example, MoCl5 is selective, while MoO2Cl2 is not; that is, under the same temperature and pressure conditions, the precursor gas of MoCl5 may deposit Mo only on conductive surfaces and not on dielectric surfaces, while the precursor gas of MoO2Cl2 will deposit Mo on both conductive and dielectric surfaces. Generally, MoCl5 gas has a large process window, i.e., a wide range of temperature and pressure, where the precursor gas retains its selectivity. For example, MoCl5 can selectively deposit on metallic materials relative to dielectric materials with process temperatures of 300°C to 800°C. In some embodiments, the substrate temperature is 350°C to 550°C. Generally, higher process temperatures and higher process pressures reduce the selectivity of the deposited film. For example, at higher temperatures, a precursor gas such as MoCl5 may lose its selectivity and deposit Mo films on both metallic and dielectric surfaces within the characteristic range.

[0085] In some embodiments, Operation 505 can be a thermal or plasma-based process. In some embodiments, Operation 505 is a plasma-enhanced ALD (PEALD) or plasma-enhanced CVD (PECVD) process using a molybdenum halide precursor. In some embodiments, the molybdenum halide precursor is MoCl5. Hydrogen (H2) or other reducing agents can be used for PEALD or PECVD deposition.

[0086] In some embodiments, operation 505 can be a thermal process. Selectivity can also be readily achieved using thermal processes. In some such embodiments, operation 505 can involve a pulsed chemical vapor deposition (pulsed CVD) process. A pulsed CVD process for selective molybdenum deposition is further described below with reference to Figures 7-9.

[0087] Figure 6A shows a cross-sectional representation of the features during various stages of the process of Figure 5. The feature, including a conductive bottom material 602 and dielectric sidewalls 604, is provided to a processing tool where it undergoes a pretreatment operation as described in operation 503 of Figure 5. For example, after pretreatment, the surface of the conductive bottom material may be free of oxides and other residues. Selective deposition is then performed to deposit Mo 606 at the bottom of the feature. Mo is selectively deposited on the conductive bottom material 602, while no significant deposition is observed on the dielectric sidewalls 604. This describes an example of a feature after operation 505 of Figure 5, where a Mo layer is present in the feature without any deposits on the sidewalls above the layer.

[0088] Returning to Figure 5, a conformal Mo pad is deposited in operation 507. The conformal Mo pad is deposited using a non-selective method of deposition on both the Mo prefill layer and the dielectric sidewalls. In some embodiments, MoO2Cl2 can be used to deposit the conformal layer. Deposition can be PEALD deposition using MoO2Cl2. Thermal ALD can be used to deposit the conformal layer using MoO2Cl2 at temperatures above about 400°C. In some embodiments, MoCl5 can be used in conjunction with PEALD to deposit the conformal layer. As shown in Figure 6A, a conformal Mo pad 608 is deposited in the feature.

[0089] Returning to Figure 5, the process can continue with Mo-filled features in operation 509. The same or different Mo precursors can be used in operations 507 and 509. Operation 509 may include one or more deposition, suppression, and etching operations, as described below. The order of these operations and the precursors used may depend on the feature profile. For example, if the feature is recessed, one or more etching and / or suppression operations can be used to adjust the filling. For example, for less complex structures, such as V-shaped structures, PEALD using MoO2Cl2 can be used. In some embodiments, these structures can also be filled using a pulsed CVD process. Possible filling techniques for recessed features will be further described below. Figure 6A shows the structure after filling, where a host Mo film 601 is present in the feature.

[0090] Figure 6B shows an example of a subprocess that can be performed for interconnect metallization. In the example of Figure 6B, all operations described with reference to Figure 5 or Figure 6B are performed in a single chamber, which can be a multi-station or single-station chamber. Such a chamber can be configured to deliver two solid precursors (e.g., MoCl5 and MoO2Cl2). The example of Figure 6B refers to various suppression and deposition-etch-deposition (DED) operations. These will be described in more detail below. In other embodiments, any one or more operations can occur in different chambers. In some embodiments, these can be connected by vacuum.

[0091] Figure 6B illustrates a single-chamber interconnect metallization process, including pretreatment, selective prefilling, conformal padding, and final fill operations. Interconnect metallization may include all or a subset of these operations. For example, a single-chamber metallization process may include pretreatment, selective prefilling, followed by deposition, resulting in complete feature filling. For instance, Figure 6B shows PECVD using MoO2Cl2 for conformal padding and final fill. A PECVD operation performed after pretreatment and / or selective fill can be used to fill a feature without forming a conformal pad as part of a separate fill operation. This can also be characterized as conformal pad deposition continuing until the feature is filled. Other examples of single-chamber fill processes include: Pretreatment / Conformal Pad / Final Filling Preprocessing / Selective prefilling / Final filling Preprocessing / Selective Filling (Selective deposition continues until feature filling is complete) Any one or more of the described subprocesses can be used for each of pretreatment, selective prefilling, conformal lining, and final filling. Regarding pretreatment, as described above, pretreatment can be thermal or plasma treatment. An example of thermal treatment is exposure to a metal halide. This can be molybdenum halide or other metal halides, such as tungsten halides, as described above. Tungsten hexafluoride (WF6) or MoF6 can be used in some embodiments. These pretreatment agents are gases at standard pressures and temperatures, which allow delivery via a mass flow controller at room temperature. Direct or remote plasma pre-cleaning can be used. Exposure to reducing plasmas (e.g., H2 plasma) can be performed. For interconnect metallization, the incoming bottom surface can be a conductive surface. Examples include elemental metal films such as tungsten, molybdenum, copper, cobalt, titanium, ruthenium, or metal-containing conductive compound films such as titanium nitride and tungsten nitride. Sidewall surfaces are dielectric surfaces and include silicon oxides, silicon nitrides, silicon carbides, silicon oxycarbides, silicon nitrides, aluminum oxides, and so on. As described above, pretreatment can be used to remove surface oxides from conductive surfaces and / or treat dielectric sidewalls.

[0092] Selective prefilling (if performed) results in preferential deposition on a conductive surface relative to the dielectric surface. In some embodiments, it is performed to reduce the aspect ratio of the feature for subsequent filling. Processes that can be used include thermal deposition using molybdenum halides (e.g., MoCl5 or MoF6). Thermal deposition can be atomic layer deposition (ALD), pulsed chemical vapor deposition (pulsed CVD), or continuous flow CVD. ALD is a surface-mediated deposition technique in which doses of Mo halide precursor and hydrogen (H2) are sequentially introduced into the deposition chamber, optionally purged with argon or other inert gases between the sequential reactant doses. One or more cycles of sequential doses of molybdenum precursor and H2 are used for selective deposition of Mo. In continuous flow thermal CVD, Mo halide and H2 flow simultaneously into the chamber for a gas-phase reaction. Pulsed CVD process sequences may involve continuous flow of one or more process gases and pulsed flow of one or more other process gases. Examples of pulsed CVD processes are given below, as shown in Figures 7-9.

[0093] Selective deposition on conductive surfaces relative to dielectric surfaces is an inherent characteristic of thermal ALD, thermal CVD, and thermal pulsed CVD performed under appropriate conditions using molybdenum halides and hydrogen (H2). As described below, MoCl5 and MoF6 have large process windows, i.e., wide temperature and pressure ranges, in which the precursor gas maintains its selectivity. For example, MoCl5 can be used to selectively deposit molybdenum relative to dielectric materials on metals or metallic conductive materials, with process temperatures ranging from 200°C to 800°C, such as 250°C to 550°C, or 300°C to 500°C. Generally, higher process temperatures and higher process pressures reduce the selectivity of deposition. However, selectivity is significantly controlled by the precursor species (identity), with molybdenum halides causing much higher selectivity than molybdenum oxyhalides. Using reducing agents stronger than hydrogen also reduces selectivity. These include, for example, silanes and diboranes. In some embodiments, plasma deposition can be used for selective pre-filling. In such embodiments, the plasma can be a remote plasma, where hydrogen radicals generated in a plasma generator remote from the processing chamber are fed into the reactor. The thermal ALD, thermal CVD, and thermal pulsed CVD described herein can be modified to utilize hydrogen radicals flowing into the chamber instead of hydrogen gas to achieve selective deposition.

[0094] As described above, selective deposition refers to deposition preferentially occurring on one surface type rather than another. According to various embodiments, a feature with two material types (e.g., a conductive metal bottom and dielectric sidewalls) can be provided to the chamber. In other embodiments, a feature with a single material type can be provided to the chamber, which is treated to allow selective deposition. For example, the feature can be provided with a conformally conformally laid TiN pad on the bottom and sidewalls of the feature. It can be exposed to a high-temperature molybdenum halide of the TiN layer preferentially etched at the top of the surface to form a TiN cup at the bottom of the feature and expose the dielectric sidewalls at the top of the surface. Molybdenum can then be selectively deposited on the TiN cup. The molybdenum halide exposure can be performed as part of the pretreatment process described above. In another example, a feature with a uniform surface material can be treated by suppressing deposition on a portion of the feature. For example, a suppression treatment can be performed to suppress deposition at feature openings.

[0095] Conformal pad deposition is typically performed via an ALD process rather than CVD to facilitate conformal deposition of the pad onto the feature contour. PEALD or thermal ALD can be used. If the feature has multiple material types (e.g., as shown in Figure 6A), direct plasma PEALD can be used with molybdenum halides because it results in conformal, non-selective deposition rather than selective deposition on conductive surfaces. An exemplary PEALD process using MoCl5 might use a substrate temperature of 300°C or higher. For molybdenum halide oxides, thermal or plasma ALD can be used. For thermal ALD, the temperature is high enough for deposition to occur; for example, MoO2Cl2 and H2 deposition can be used at 450°C or higher. For PEALD utilizing MoO2Cl2, a wide temperature range can be used. For example, substrate temperatures from 100°C to 600°C can be used.

[0096] If the feature itself is not selective, i.e., it has a uniform material throughout, for example, a previously formed liner film, and the liner film is retained in the device, then the conformal liner can be formed by any ALD process (thermal or plasma) using any molybdenum halide or oxyhalide precursor that can be deposited.

[0097] An example of the final filling sub-process is also shown in Figure 6B. As mentioned above, filling recessed structures is more challenging and may require one or more suppression or etching processes to achieve the filling. In the example of the recessed structure described in Figure 6B, the filling process using molybdenum oxyhalide or molybdenum halide can employ a deposition-etch-deposition (DED) or deposition-suppression-deposition (DID) process. As further described below, more complex processes (including processes with one or more deposition, etching, suppression, and desuppression processes) can be performed to achieve pore-free filling.

[0098] Figure 6B also shows the suppressor process used in molybdenum oxyhalide and molybdenum halide deposition processes. Suppression refers to inhibiting molybdenum nucleation, which will be described further below. For example, halogenating dielectric or conductive materials inhibits subsequent nucleation. Examples of halogen-containing suppressors include NF3, BCl3, MoCl5, and Cl2.

[0099] For the DED process, Figure 6B shows examples of two alternative sub-processes—discrete intermittent DED and simultaneous DED. A discrete intermittent DED process might involve the deposition of a first molybdenum film, followed by partial etching of that film, and then a second deposition of the molybdenum film. For the ALD process, etching operations can be performed between any number of deposition cycles to adjust the feature profile. One or more DED processes can be performed during fill. For the CVD process, deposition can be stopped and etching performed at appropriate times to adjust the feature profile. A simultaneous DED process might involve adding an etchant to a reducing agent to preferentially etch a portion of the film during deposition. For example, during a PEALD cycle, an etchant such as chlorine (Cl2) can be added to the H2 gas during plasma H2 operation.

[0100] Meanwhile, DED can also be called hybrid DED, where deposition and etching operations overlap in time. Figure 6B also shows an example of a hybrid DED based on molybdenum halides. Unlike molybdenum oxyhalides such as MoO2Cl2 or MoOCl4, molybdenum halides such as MoCl5 or MoF6 etch the deposited molybdenum. An example of a hybrid process might be reducing H2 and / or increasing molybdenum halide flow to achieve net etching at feature openings.

[0101] For V-shaped structures to be filled, filling is relatively easy, and any suitable ALD or CVD process, whether thermal or plasma-enhanced, can be used. CVD processes include continuous flow and pulsed CVD processes. The sub-processes identified under the "V-shaped" structure can be performed for any feature that is relatively easy to fill. In some implementations, these sub-processes can be used as a final filling operation for more challenging structures that have already been partially filled.

[0102] Another example of monochamber metallization is illustrated with reference to Figures 6C-6F. Figures 6C-6G show schematic diagrams of another example of monochamber metallization. In Figure 6C, feature 601 with a TiN pad layer 615 is shown. Feature 601 has a bottom surface 605 and a sidewall surface 611. In Figure 6A, the TiN pad is the bottom surface 605 and the sidewall surface 611. In some embodiments, the pad layer may be titanium silicon nitride (TiSi). x(N) Pad layer. In some embodiments, the TiN layer 615 may be oxidized on the top surface of this layer. Feature 601 is formed in dielectric material 613. Lower stack 610 is located below the bottom surface 605 of feature 605. In the example shown, lower stack 610 has metal silicide nitride (MSi) x N y ) layer 608 and metal silicide layer (MSi x 607 and a semiconductor layer 606, such as silicon (Si) or silicon germanium (SiGe), connected thereto. This stack 610 can be used in transistor junction structures. An example of an MSix layer is titanium silicide (TiSi). x ), and metal silicide nitrides (MSi x N y ) is titanium silicide nitride (TiSi) x N y A TiN pad layer 615 on the bottom surface 605 is used to protect the underlying stack 610 below the feature bottom surface. The TiN pad layer can act as a diffusion barrier layer to prevent etching of the underlying material and to prevent oxidation of the underlying material.

[0103] Figure 6D depicts feature 601 undergoing pretreatment, as described above with respect to Figure 6B. The figure shows the feature being immersed in Mo halide precursor 619 to remove any oxides from its surface. For example, TiN... x O y The TiN layer 615 can be removed, leaving it intact. Furthermore, a high-temperature Mo halide immersion etching process removes any TiN layer on the field portion and may remove some or all of the TiN layer on the substrate sidewalls. In the illustrated embodiment, a portion of the TiN layer 615 remains on the sidewalls, such that the TiN layer is thicker at the bottom portion of the sidewall relative to the upper portion. The TiN layer is retained as the bottom surface 605 and is likely the thickest portion of the remaining TiN layer in feature 601. The TiN layer is retained as the bottom surface 605 to protect the underlying stack 610 during subsequent processing.

[0104] Figure 6E shows feature 701 after the initial Mo layer 621 has been deposited. The Mo layer 621, as described in Figure 6B, is deposited using an ALD process utilizing a Mo halide precursor (such as MoCl5) and a reducing agent. As shown, the initial Mo layer 621 is selectively deposited on the TiN layer 615 within the feature, covering the sidewalls and the bottom of the feature. The Mo layer 621 is deposited directly on the TiN layer 615 without being deposited on any dielectric surface.

[0105] Figure 6F shows feature 602 after the second etching process. The etching process may be similar to the cleaning and etching process used in Figure 6D. Feature 601 may be immersed using a Mo halide precursor 619. In some embodiments, the immersion may be continuous. In other embodiments, the immersion may be multiple cycles of alternating dosing of the Mo halide precursor and purge gas. The etching in Figure 6F may be a more aggressive etching than that shown in Figure 6D. This etching removes the Mo and TiN layers from the feature sidewalls. As shown, dielectric material 613 forms the sidewall surface 611 after etching. The etching leaves the TiN layer 615 and Mo layer 621 on the bottom of feature 601, so that they form the bottom surface 604 and protect the underlying stack 610. Cleaning removes any oxides or contaminants from the surface.

[0106] Figure 6G shows feature 601 after Mo interstitial filling, as described above with respect to the feature in Figure 6B. Feature 601 is filled with Mo filler 623. A TiN layer 615 remains between the Mo filler 623 and the underlying stack 610. Feature 601 can be filled using thermal or plasma ALD or CVD processes. The filling can be accomplished using oxygen-containing Mo oxyhalide precursors, oxygen-free Mo halide precursors, or combinations thereof. In some embodiments, the filling can be conformal filling followed by interstitial filling or bottom-up filling. In some embodiments, the filling can be performed in a single-stage deposition, where the filling continues using the same parameters (e.g., temperature and pressure) as the initial filling. In other embodiments, the filling can be performed in a multi-stage Mo deposition, where the parameters can be changed during deposition. For example, the first stage of deposition may have a first temperature. After the first stage, the deposition may continue in a second stage, possibly with a second temperature higher than the first temperature. The increase in temperature can be used to increase the rate of Mo bulk filling, thereby reducing processing time. In another example of multi-stage deposition, the concentrations of Mo precursors and reactants may differ at different stages.

[0107] molybdenum deposition The molybdenum deposition described herein involves reacting a Mo-containing precursor (also known as a molybdenum precursor). In some embodiments, a molybdenum halide compound as described above is used. In methods including surface treatment using molybdenum halide compounds, the same or different compounds may be used for deposition.

[0108] In some implementations, the Mo precursor is molybdenum chloride (MoCl₂). x ) compound, also known as molybdenum chloride precursor or MoCl x Precursor. The molybdenum chloride precursor is derived from the formula MoCl. xThe expression is given, where x is 2, 3, 4, 5, or 6, and includes molybdenum dichloride (MoCl2), molybdenum trichloride (MoCl3), molybdenum tetrachloride (MoCl4), molybdenum pentachloride (MoCl5), and molybdenum hexachloride (MoCl6). In some embodiments, MoCl5 or MoCl6 is used. Although the description primarily relates to MoCl... x The precursor is molybdenum halide, but in other embodiments, other molybdenum halide precursors may be used. The molybdenum halide precursor is of the formula MoX. z Given, where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and z is 2, 3, 4, 5, or 6. MoX z Examples of precursors include molybdenum fluoride (MoF6). In some embodiments, fluorine-free MoX is used. z Precursors are used to prevent fluorine etching or incorporation. In some embodiments, bromine-free and / or iodine-free MoX is used. z Precursors are used to prevent etching or the incorporation of bromine or iodine.

[0109] In some implementations, molybdenum halide precursors can be used to fill the features. Molybdenum halide precursors are derived from the formula MoO. y X z Given that X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)), and y and z are numbers greater than 0, such that MoO y X z They form stable compounds. Examples of molybdenum halide oxides include molybdenum dichlorodioxide (MoO2Cl2), molybdenum tetrachlorodioxide (MoOCl4), molybdenum tetrafluoride (MoOF4), molybdenum dibromodioxide (MoO2Br2), and molybdenum iodide (MoO2I and Mo4O). 11 I. It should be understood that, as used herein, the term molybdenum halide precursor can refer to the molybdenum halide precursor as described above or a molybdenum-containing halide precursor comprising molybdenum, oxygen, halides, and one or more other elements. In some embodiments, the molybdenum halide or molybdenum-containing halide may comprise a variety of different halogens (e.g., F and Cl and / or I and / or Br, etc.). MoX may be used. x Precursor, MoO y X z Precursors or combinations thereof are used to fill features with molybdenum.

[0110] To deposit molybdenum into features, molybdenum precursors can react with co-reactants. Examples of co-reactants include hydrogen (H2), silane (SiH4), diborane (B2H6), germanane (GeH4), ammonia (NH3), and hydrazine (N2H4). Ammonia and hydrazine can be used to deposit molybdenum nitrides or molybdenum oxides.

[0111] In some implementations, molybdenum deposition can be performed using a plasma-based process. A gas can be fed into a remote or in-situ plasma generator to produce a plasma material. Examples of gases that can be used to generate the plasma include hydrogen-containing gases, such as H2, nitrogen-containing gases, such as nitrogen (N2), and other gases such as Ar and NH3. The plasma material can be inert or react with a molybdenum precursor to form a film.

[0112] Features can be filled with molybdenum using atomic layer deposition (ALD) or chemical vapor deposition (CVD). Thermal ALD or plasma-enhanced ALD (PEALD) can be used. Similarly, thermal CVD or plasma-enhanced CVD (PECVD) can be used.

[0113] Alternating current deposition (ALD) is a surface-mediated deposition technique in which a predetermined dose of precursor and reactant is sequentially introduced into a deposition chamber. One or more cycles of sequential dosing of the molybdenum precursor and reactant can be used to deposit Mo. For example, in the deposition of the initial molybdenum layer (e.g., as shown in operation 505 or 507 of Figure 5), MoCl5 can be used as a precursor and H2 can be used as a reducing agent. A predetermined dose of MoCl5 and H2 is sequentially introduced into the deposition chamber, and a purge gas (e.g., argon) flows between the deposition chambers. For ALD, the temperature of the substrate and the pressure of the chamber can be controlled. For example, the substrate can be heated to between 200°C and 800°C, such as between 250°C and 550°C, or between 300°C and 500°C, or between 350°C and 450°C. In some embodiments, the chamber can be pressurized to between 10 Torr and 200 Torr, such as between 50 Torr and 90 Torr. In some embodiments, temperature and / or pressure can be used to control the reaction rate. In some embodiments, temperature and / or pressure can be used to control selectivity.

[0114] In some implementations, the Mo precursor is molybdenum fluoride (MoF). x ) compounds, also known as molybdenum fluoride precursors or MoF x Precursor. The molybdenum chloride precursor is composed of the chemical formula MoF. x Given, where x is 4, 5 or 6, and includes molybdenum tetrafluoride (MoF4), molybdenum pentafluoride (MoF5) and molybdenum hexafluoride (MoF6).

[0115] MoF6 may be advantageous because of its boiling point of 34°C. Being a gas at standard pressure and 35°C allows MoF6 to be delivered through a mass flow controller (MFC) at room temperature without heating and without condensation or particle formation. However, MoF6 is a corrosive etchant, and exposure to MoF6 during the process can lead to substitutional Mo deposition or etching outside of Mo deposition. In some embodiments, deposition using MoF6 involves providing a flow of MoF6 in the process gas, where the molar concentration of MoF6 is 0.01% or less. In some embodiments, the concentration can be significantly lower, 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): 100 ppm (100 MoF6 molecules / 1 million gas particles (atoms, molecules)) or less, 80 ppm or less, or 40 ppm or less. For example, at temperatures between 200°C and 650°C, a molar concentration of 0.004% or less can lead to CVD deposition when flowing with H2 and argon. Higher temperatures can be used to promote the deposition reaction and allow for higher concentrations of MoF6, such as up to 0.01%. In some embodiments, the concentration can be 0.0039% or 0.0035% or less. In some embodiments, the MoF6 concentration is at least 0.00004% or at least 0.0001%. For example, in the case of growth on bare metal surfaces, the concentration may be very low.

[0116] Depositions using MoF6 and H2 as reducing agents occur only at exceptionally low concentrations. For example, for 0.5 sccm of MoF6, a total flow rate of 13,500 sccm can be used for a MoF6 concentration of 0.0037%. Depositions using metal halides and hydrogen typically involve much higher concentrations. For example, molybdenum deposition using molybdenum hexachloride and hydrogen can be performed at concentrations 5 to 10 times higher than those used for MoF6.

[0117] In some implementations, MoF6 can be used at higher concentrations and lower temperatures when using a reducing agent stronger than hydrogen. Lower temperatures can reduce or prevent etching of MoF6; however, at low temperatures, H2 may not cause deposition. Stronger reducing agents, such as silanes, disilanes, polysilanes, and diboranes, can be used for deposition at lower temperatures (e.g., below 200°C). The resulting films may not be pure molybdenum and, in some cases, may be more resistive than films deposited using H2 as a reducing agent. For these reasons, they may not be suitable for certain applications.

[0118] In some implementations, molybdenum filling can involve CVD. In a CVD process, the molybdenum precursor and reactants are in the gaseous phase together in a deposition chamber. Generally, CVD processes fill features faster than ALD processes. In one example, the precursor might be a molybdenum oxychloride, such as MoO2Cl2, which flows into the chamber along with reactants (such as H2). In this example, the wafer is simultaneously exposed to both the precursor and reactants, which react and fill the feature with Mo. In another example, MoF6 flows into the chamber along with reactants (such as H2). In this example, the wafer is simultaneously exposed to both the precursor and reactants, which react and fill the feature with Mo.

[0119] In some other embodiments, a pulsed CVD process can be used to fill the feature. A pulsed CVD process involves the continuous inflow of reactants into the chamber while a pulse of precursor is simultaneously inflowed into the chamber. For example, H2 gas may flow into the chamber continuously while a molybdenum-containing precursor flows into the chamber intermittently. During CVD operation, the temperature of the substrate and the pressure in the chamber can be controlled. Figures 7-9 show examples of pulsed CVD processes. Figure 7 shows a timing diagram illustrating various operations that can be performed according to certain disclosed embodiments. Process 701 includes two deposition cycles 710A and 710B, but it should be understood that, according to certain disclosed embodiments, only one cycle or more than two cycles may be performed. In this example, deposition cycles 710A and 710B include the same operations repeated in each cycle, but it should be understood that, in some embodiments, various operations, or such a variety of operations as described later with respect to Figures 8 and 9, may be combined with the cycles described herein with respect to Figure 7.

[0120] Figure 7 illustrates the various process conditions during each stage—four process conditions are described here, but it should be understood that other gases, plasmas, temperatures, pressures, or other conditions may also be present, and may vary or be the same between different stages and different cycles. The process conditions shown in this example include a first hydrogen-containing gas source (which may be a first source of hydrogen (H2), a second hydrogen-containing gas source (which may be a second source of hydrogen (H2), argon (which may be used as a purge gas, carrier gas, inert gas, or any combination thereof), and a molybdenum-containing precursor gas.

[0121] In this example, the deposition cycle 710A comprises four stages—a first stage 720A, a first purge stage 740A, a second stage 750A, and a second purge stage 780A. During the first stage 720A, the first hydrogen source gas is turned on, the second hydrogen gas source is turned on, the argon source is turned off, and the molybdenum precursor gas source is turned off. During this operation, only the hydrogen-containing gas source may be allowed to flow.

[0122] During the first purge phase 740A, the first hydrogen source gas may remain on (and may continue to flow at the same flow rate), the second hydrogen source gas may be off or reduced (e.g., reduced flow rate), the argon source gas may be on, while the molybdenum precursor gas source remains off.

[0123] During the second stage 750A, the first hydrogen gas source may remain on (and may continue to flow at the same flow rate), the second hydrogen gas source may remain off (or at a lower flow rate), the argon gas source may be off (or has been reduced in flow rate), and the molybdenum precursor gas source may be on.

[0124] During the second purge phase 780A, the first hydrogen source gas may remain on (and may continue to flow at the same flow rate), the second hydrogen source gas may remain off or reduced (e.g., at a reduced flow rate), the argon source gas may be on, and the molybdenum precursor gas source system is off.

[0125] Although the process flow shows the second hydrogen source being turned on followed by the molybdenum precursor gas being turned on, it should be understood that alternative methods can be used (e.g., the molybdenum precursor gas is turned on, then purge, then the second hydrogen source is turned on, then purge).

[0126] Deposition cycle 710A is then repeated in deposition cycle 710B. Deposition cycle 710B comprises four stages—stage 720B, first purge stage 740B, second stage 750B, and second purge stage 780B. Stage 720B may be the same as or different from stage 720A. In this example, stage 720B is the same as stage 720A. During stage 720B, the first hydrogen source gas remains on, the second hydrogen gas source is on, the argon source is off, and the molybdenum precursor gas source is off. During this operation, only the hydrogen gas source can flow.

[0127] During the first purge phase 740B, the first hydrogen source gas may remain on (and may continue to flow at the same flow rate), the second hydrogen source gas may be turned off or reduced (e.g., at a reduced flow rate), the argon source gas may be turned on, while the molybdenum precursor gas source remains off.

[0128] During the second stage 750B, the first hydrogen gas source may remain open (and may continue to flow at the same flow rate), the second hydrogen gas source may remain closed (or at a lower flow rate), the argon gas source may be closed (or have a reduced flow rate), and the molybdenum precursor gas source is open.

[0129] During the second purge phase 780B, the first hydrogen source gas may remain open (and may continue to flow at the same flow rate), the second hydrogen source gas may remain closed or reduced (e.g., at a reduced flow rate), the argon source gas may be opened, and the molybdenum precursor gas source gas may be closed.

[0130] Figure 8 illustrates alternative deposition cycle schemes that may be used in certain embodiments. Figure 8 shows a timing diagram illustrating various operations that can be performed according to certain disclosed embodiments. Process 800 includes two deposition cycles 810A and 810B, but it should be understood that only one cycle or more than two cycles can be performed according to certain disclosed embodiments. In this example, deposition cycles 810A and 810B include the same operations repeated in each cycle, but it should be understood that in some embodiments, various operations, or such a variety of operations as described with respect to Figures 7 and 9, can be combined with the cycles described herein with respect to Figure 8.

[0131] Figure 8 illustrates the various process conditions during each stage—three process conditions are described here, but it should be understood that other gases, plasmas, temperatures, pressures, or other conditions may also be present and may vary or be the same in different stages and cycles. The process conditions shown in this example include a molybdenum precursor gas, a hydrogen gas source (which may be a source of hydrogen (H2),) and argon (which may act as a purge gas, carrier gas, inert gas, or any combination thereof). In this example, the molybdenum precursor gas source can flow continuously.

[0132] In this example, the deposition cycle 810A comprises four stages—stage 820A, first purge stage 840A, second stage 850A, and second purge stage 880A. During stage 820A, the molybdenum precursor gas is turned on, the hydrogen gas source is turned on, and the argon source is turned off.

[0133] During the first purge phase 840A, the molybdenum precursor gas source remains open (and may continue to flow at the same rate), the hydrogen source gas may be shut off (or have a reduced rate), and the argon gas is on.

[0134] During the second stage 850A, the molybdenum precursor gas source remains on (and may continue to flow at the same rate), the hydrogen source gas can be turned on, and the argon gas is turned off (or has a reduced flow rate).

[0135] During the second purge phase 880A, the molybdenum precursor gas source remains open (and may continue to flow at the same flow rate), the hydrogen source gas may be shut off (or have a reduced flow rate), and the argon gas is on.

[0136] Although the process flow shows that the hydrogen source is turned on and then the argon gas is turned on, it should be understood that alternative methods can be used instead (e.g., purge, then turn on the hydrogen source, then purge, then turn on the hydrogen source).

[0137] Deposition cycle 810A is then repeated in deposition cycle 810B. Deposition cycle 810B comprises four stages—stage 820B, first purge stage 840B, second stage 850B, and second purge stage 880B. Stage 820B may be the same as or different from stage 820A. In this example, stage 820B is the same as stage 820A. During stage 820B, the molybdenum precursor gas is turned on, the hydrogen gas source is turned on, and the argon source is turned off.

[0138] During the first purge phase 840B, the molybdenum precursor gas source remains open (and can continue to flow at the same flow rate), the hydrogen source gas can be shut off (or have a reduced flow rate), and the argon gas is on.

[0139] During the second stage 850B, the molybdenum precursor gas source remains on (and may continue to flow at the same flow rate), the hydrogen source gas can be turned on, and the argon gas is turned off (or has a reduced flow rate).

[0140] During the second purge phase 880B, the molybdenum precursor gas source remains open (and may continue to flow at the same rate), the hydrogen source gas may be shut off (or have a reduced flow rate), and the argon gas is on.

[0141] Figure 9 illustrates yet another alternative deposition cycle scheme that can be used in certain embodiments. Figure 9 shows a timing diagram illustrating various operations that can be performed according to certain disclosed embodiments. Process 900 includes two deposition cycles 910A and 910B, but it should be understood that only one cycle or more than two cycles can be performed according to certain disclosed embodiments. In this example, deposition cycles 910A and 910B include the same operations repeated in each cycle, but it should be understood that in some embodiments, various operations, or such a variety of operations as described with respect to Figures 7 and 8, can be combined with the cycles described herein with respect to Figure 9.

[0142] Figure 9 illustrates the various process conditions during each stage—three process conditions are described here, but it should be understood that other gases, plasmas, temperatures, pressures, or other conditions may also be present and may vary or be the same in different stages and cycles. The process conditions shown in this example include a hydrogen-containing gas source (which can be a source of hydrogen (H2)), a molybdenum-containing precursor gas, and argon (which can act as a purge gas, carrier gas, inert gas, or any combination thereof). In this example, the molybdenum precursor gas source can flow continuously. In this example, the hydrogen-containing gas source can flow continuously.

[0143] In this example, deposition cycle 910A comprises four cycles—stage 920A, first purge stage 940A, second stage 950A, and second purge stage 980A. During stage 920A, the molybdenum precursor gas is turned on, the hydrogen gas source is turned on, and the argon source is turned off.

[0144] During the first purge phase 940A, the molybdenum precursor gas source remains open (and can continue to flow at the same flow rate), the hydrogen source gas remains open (and can continue to flow at the same flow rate), and the argon gas is on.

[0145] During the second stage 950A, the molybdenum precursor gas source remains open (and may continue to flow at the same flow rate), the hydrogen source gas remains open (and may continue to flow at the same flow rate), and the argon gas is closed (or has a reduced flow rate).

[0146] During the second purge phase 940A, the molybdenum precursor gas source remains open (and can continue to flow at the same flow rate), the hydrogen source gas remains open (and can continue to flow at the same flow rate), and the argon gas is on.

[0147] Deposition cycle 910A is then repeated in deposition cycle 910B. Deposition cycle 910B comprises four stages—stage 920B, first purge stage 940B, second stage 950B, and second purge stage 980B. Stage 920B may be the same as or different from stage 920A. In this example, stage 920B is the same as stage 920A. During stage 920B, the molybdenum precursor gas is turned on, the hydrogen gas source is turned on, and the argon source is turned off.

[0148] During the first purge phase 940B, the molybdenum precursor gas source remains open (and can continue to flow at the same flow rate), the hydrogen source gas remains open (and can continue to flow at the same flow rate), and the argon gas is on.

[0149] During the second stage 950B, the molybdenum precursor gas source remains open (and can continue to flow at the same flow rate), the hydrogen source gas remains open (and can continue to flow at the same flow rate), and the argon gas is closed (or has a reduced flow rate).

[0150] During the second purge phase 940B, the molybdenum precursor gas source remains open (and can continue to flow at the same flow rate), the hydrogen source gas remains open (and can continue to flow at the same flow rate), and the argon gas is on.

[0151] The molybdenum-containing precursor used for molybdenum deposition can be any suitable precursor, such as those listed in the Precipitates section below. Examples also include molybdenum halides and / or organometallic molybdenum-containing precursors. One or more precursors may be used.

[0152] In various embodiments, the first and / or second hydrogen-containing source gas can be hydrogen. The hydrogen can continue to flow to prevent damage to the substrate when it is exposed to the molybdenum-containing precursor.

[0153] Although argon is described in accordance with Figures 7-9, it should be understood that other inert gases, including but not limited to helium, may be used instead of argon.

[0154] Plasma-enhanced CVD can be used, where the plasma is ignited during deposition. In pulsed CVD processes, the plasma may be ignited during deposition cycles or, for example, during hydrogen reactant pulses. In some embodiments, remote plasma can be used. This plasma can be remotely generated or directly generated. Furthermore, it can be generated by any suitable plasma generator, including capacitively coupled plasma generators or inductively coupled plasma generators. Microwave plasma generators can be used.

[0155] Figure 10A shows an example of molybdenum deposition via an atomic layer deposition (ALD) process. In the example of Figure 10A, in operation 1001, the substrate is exposed to a process gas containing a molybdenum precursor. A purging operation is then performed in operation 1003. The adsorbed layer containing the molybdenum precursor is retained, while the gaseous precursor is removed. The substrate is then exposed to a reactant in operation 1005. This is typically a reducing agent, such as hydrogen. In plasma processes using direct plasma, the plasma is ignited during this operation. In plasma processes using direct plasma, the reactant includes remotely generated plasma material (e.g., hydrogen radicals). The reactant reacts with the adsorbed precursor to form a molybdenum layer. A purging operation is then performed in operation 1007. Operations 1001-1007 can then be repeated until the molybdenum film reaches the target thickness in operation 1009.

[0156] Modifications to the process described in Figure 10A may include exposure to reactants as the first operation in each cycle, followed by a purge, exposure to a molybdenum-containing compound, and another purge. Further modifications may include forming less than one monolayer per cycle. This can be performed by limiting the amount of one or two reactants. In some embodiments, the ALD process may not be strictly self-limiting. For example, one or both of the purge operations may be omitted or shortened to allow some gas-phase reactants to remain and react in the gas phase. This can increase the deposition rate. Further modifications may include repeating operation 1001 (with or without an intermediate purge) before performing operation 1005 within a cycle. In some embodiments, operation 1005 is repeated once or more within a cycle. Such modifications facilitate diffusion through the characteristic. Furthermore, in some embodiments, the reactants may be, for example, nitrogen-containing, such that a molybdenum nitride or molybdenum oxynitride layer is formed.

[0157] Selective deposition Molybdenum can be selectively deposited into features using the methods described herein. Selective deposition refers to the preferential deposition of molybdenum onto a first material relative to a second material. Molybdenum can be more easily deposited and grown on metallic materials than on dielectric materials. For example, a feature may have a SiO2 sidewall surface and a TiN plug in the bottom of the feature. In selective deposition, molybdenum is deposited into the feature and can grow on the TiN plug, but not (or to a lesser extent) on the SiO2 sidewall surface.

[0158] Process conditions such as precursor gas, reducing agent, process temperature, process pressure, and exposure time can affect the selectivity of the deposited molybdenum film. The process temperature for selective molybdenum film deposition can be between 200°C and 800°C, for example, 250°C to 550°C or 300°C to 500°C. At these temperatures, the molybdenum film is selectively deposited on the surface of a conductive metal or metal compound, such as TiN, relative to the dielectric surface.

[0159] Different precursor gases can have different process windows, allowing for the selective deposition of molybdenum films. Generally, MoCl5 has a large process window, i.e., a wide temperature and pressure range, where the precursor gas retains its selectivity. For example, MoCl5 can be selectively deposited on metallic materials relative to the dielectric material, with process temperatures ranging from 200°C to 800°C, such as 250°C to 550°C, or 300°C to 500°C. Generally, higher process temperatures and higher process pressures reduce the selectivity of the deposition gas. Over a wide temperature range, MoCl5 selectively deposits on metals, titanium nitrides (TiN), and other conductive materials relative to the dielectric material.

[0160] MoCl5 can react with various reactants to deposit molybdenum films. Examples of molybdenum film deposition within a feature area using MoCl5 precursors and different process controls are described below. In a first example, the above-described deposition method is used to react the MoCl5 precursor with an H2 reactant. In the description herein, the metal precursor reacts with hydrogen (H2) as a co-reactant (also referred to as a hydrogen reactant or H2 reactant). Instead of hydrogen, other reactants can be used, including other hydrogen-containing reactants such as SiH4, B2H6, and NH3, depending on the specific application. Reactants such as B2H6 and / or SiH4 are stronger reducing agents and generally exhibit reduced selectivity. They also result in higher resistivity. Therefore, in some embodiments, the use of H2 as described herein is advantageous. As mentioned above, the process temperature for selectively depositing molybdenum films from MoCl5 can be between 200°C and 800°C, for example, between 250°C and 550°C, or for example, between 300°C and 500°C. At these temperatures, a molybdenum film is selectively deposited on the surface of a conductive metal or metal compound, such as a TiN surface, within the feature, relative to the dielectric surface. The molybdenum film grows from the location of the conductive surface within the feature. If the conductive surface is a TiN plug located at the bottom of the feature, the molybdenum film can be deposited and grown from the bottom of the feature. In the second example, a MoCl5 precursor and H2 reactants can be used to deposit the molybdenum film at a higher temperature, above 800°C. This process window allows the molybdenum film to be deposited on both the dielectric and conductive surfaces within the feature. Deposition of the molybdenum film on the dielectric surface can be used to create an unobstructed molybdenum layer within the feature.

[0161] In some implementations, MoF is used x The precursor undergoes selective deposition. The molybdenum fluoride precursor is composed of the chemical formula MoF as described above. x As mentioned above, MoF6 can facilitate simplified transport. Molybdenum deposition from the aforementioned low concentrations of MoF6 results in high (at least 100:1) selectivity of an elemental metal surface (e.g., W, Mo, Cu) relative to oxides and nitrides (such as silicon oxides and titanium nitrides). MoF6 also deposits selectively on metals relative to dielectric materials, but with lower selectivity than MoCl5. An example of MoF6 selectivity is shown in Figure 10B. It can be seen that, after a delay, MoF6 deposits on thermal oxides. The selectivity of molybdenum halides is also affected by the conditions under which molybdenum halides are etched (e.g., concentration, temperature, etc.).

[0162] Selective deposition using molybdenum oxyhalide precursors is significantly more difficult than deposition using molybdenum halide precursors. However, the surface treatment described above significantly improves the selectivity of Mo deposition from MoO₂Cl₂. As mentioned above, MoO₂... y X zExamples of precursors include MoO2Cl2, MoOCl4, MoOF4, MoO2Br2, MoO2I, and Mo4O 11 I. This feature can be filled using ALD, plasma-enhanced ALD, chemical vapor deposition (CVD), or plasma-enhanced CVD. For ALD or CVD, H2 can act as a reducing agent. In surface treatment, compared to MoCl... x For precursors, using molybdenum halide precursors allows for faster molybdenum deposition. For example, for non-plasma processes, MoO... y X z The precursor can be more readily available than MoCl x The precursor is deposited at a rate at least twice as fast as the deposition rate for molybdenum.

[0163] Non-selective deposition In some implementations, plasma deposition can be used to reduce or eliminate the aforementioned selectivity, allowing molybdenum to be deposited on different materials. This can be referred to as non-selective deposition. When using the ALD process, non-selective deposition may conform to the surface profile. Plasma is typically used for in-situ or direct plasma deposition.

[0164] Examples of plasma processes include plasma-enhanced ALD (PEALD) or plasma-enhanced CVD (PECVD) processes using molybdenum halide precursors. In some embodiments, the molybdenum halide precursor is MoCl5 or MoF6. Molybdenum oxyhalides, such as MoO2Cl2 or MoOCl4, can also be used. Hydrogen (H2) or other reducing agents can be used for PEALD or PECVD deposition.

[0165] For PECVD deposition, the molybdenum precursor can be co-flowed with the reducing agent. For MoF6, the MoF6 concentration is as described above, where the mixture is flowed into the plasma generator. Remote or direct plasma can be used. In some embodiments, capacitively coupled direct plasma generated in the chamber is employed.

[0166] Non-selective deposition can also be achieved using thermal processes employing molybdenum oxyhalides. For example, thermal MoO2Cl2 and H2 can be used for non-selective deposition of molybdenum layers. For thermal deposition using MoO2Cl2 and H2, temperatures of 450°C or higher can be used.

[0167] To reduce selectivity, an ALD process can be performed to deposit a Mo-containing nucleation layer. For nucleation layer deposition, a reducing agent stronger than hydrogen is used. This allows growth on surfaces with nucleation delays, even when hydrogen is used as a reducing agent. As described below, this reducing agent can be silicon- or boron-containing, such as silane (SiH4) or diborane (B2H6). Germanium-containing reducing agents (e.g., GeH4) can be used. These can be used to deposit elemental molybdenum films. In other embodiments, a reducing agent such as ammonia (NH3) can be used. In this case, the molybdenum layer can be a molybdenum nitride or molybdenum oxide nitride layer, depending on the presence of oxygen in the molybdenum precursor. This oxynitride or nitride layer can be converted into an elemental molybdenum layer in a subsequent process.

[0168] When using MoF6, the concentration of MoF6 in the MoF6 dose can be as described above, i.e., 0.01% or less, 0.008% or less, 0.005% or less, or 0.004% or less of the total gas flowing into the chamber. Alternatively, a higher concentration (e.g., up to 0.1% by volume molar) can be used during MoF6 because a stronger reducing agent than hydrogen is used in subsequent operations. A certain amount of reducing agent may be present to inhibit etching. As described above, this can be H2 between 0.5% and 10% or between 1% and 9%. Another reducing agent can be included in addition to hydrogen, or in addition to hydrogen. The remainder is entirely or primarily argon or other inert gas. During the reducing agent dose, the dose is entirely or primarily a reducing agent, wherein in some embodiments, a certain amount (e.g., up to 10%, or between 1% and 9%) is argon, and the remainder is a reducing agent. After nucleation layer deposition, the host molybdenum layer can be deposited using H2 as a reducing agent by any of the methods described above (including thermal or plasma-enhanced ALD or CVD).

[0169] nucleation layer In some embodiments, filling the feature may involve depositing a nucleation layer. The nucleation layer is a thin layer supporting the host deposition. It may be conformally oriented with the feature. In many embodiments, the nucleation layer is deposited via an ALD process. In some embodiments, one or more of a boron-containing reducing agent (e.g., B₂H₆) or a silicon-containing reducing agent (e.g., SiH₄) are used as co-reactants to deposit the Mo nucleation layer. For example, one or more S / Mo cycles or Mo / S cycles may be used to deposit the Mo nucleation layer. In another example, one or more B / Mo cycles or Mo / B cycles may be used to deposit the Mo nucleation layer, on which the host Mo layer is deposited. B refers to a pulse of diborane or other boron-containing reducing agent and S refers to a pulse of silane or other silicon-containing reducing agent, such that S / Mo means a silane pulse followed by a pulse of a Mo-containing precursor. Both B / Mo and S / Mo cycles (or Mo / B and / or Mo / S) can be used to deposit the Mo nucleation layer, for example, x(B / Mo) + y(S / Mo), where x and y are integers. Examples of boron-containing reactants include diborane (B2H6), alkylboranes, alkylboranes, aminoboranes (CH3)2NB(CH2)2, and carboranes such as C2B. n H n+2 Other boranes. Examples of boranes include B. n H n+4 B n H n+6 B n H n+8 B n H m , where n is an integer from 1 to 10, and m is an integer different from m. Examples of silicon-containing reducing agents include silanes (SiH4) and other silanes, such as disilane (Si2H6).

[0170] In some implementations, the deposition of the Mo nucleation layer may involve using oxygen-free precursors, such as molybdenum hexafluoride (MoF6) or molybdenum pentachloride (MoCl5). Oxygen in the oxygen-containing precursor can react with a silicon- or boron-containing reducing agent to form MoSi. x O y or MoB x O y These are impure, high-resistivity films. In some embodiments, oxygen-containing precursors can be used for nucleation layer deposition while minimizing oxygen incorporation. Oxygen incorporation can be minimized by using a high reducing agent flow rate (e.g., a reducing agent to oxygen-containing Mo precursor volumetric flow rate greater than 100:1).

[0171] In some embodiments, H2 can be used instead of boron- or silicon-containing reducing gases as the reducing gas for Mo nucleation layer deposition. Exemplary thicknesses for depositing Mo nucleation layers range from 5 Å to 30 Å. Films below this range may be discontinuous; however, this thickness is sufficient as long as they help initiate continuous bulk Mo growth.

[0172] In some embodiments, the reducing agent pulse during the deposition of the nucleation layer or the host Mo layer can be performed at a lower substrate temperature than the Mo precursor pulse. For example, the B2H6 or SiH4 (or other boron- or silicon-containing reducing agents) pulse can be performed at a temperature below 300°C, while the Mo pulse is performed at a temperature above 300°C.

[0173] In some embodiments, the reducing agent is NH3 or other nitrogen-containing reducing agents, such as hydrazine (N2H4). NH3 exhibits more favorable chemisorption on dielectrics than H2. In some embodiments, the reducing agent and precursor are selected to react without dissociation of the reducing agent. NH3 reacts with metal chlorides and metal chlorides without dissociation. This contrasts with, for example, metal chloride ALDs using H2 as a reducing agent, where H2 dissociates on the surface to form adsorbed atomic hydrogen, resulting in very low concentrations of active material and low surface coverage during the initial nucleation of the metal on the dielectric surface. By using NH3 and metal chloride or metal chloride precursors, nucleation delay is reduced or eliminated at deposition temperatures that are hundreds of degrees lower than those used for H2 reduction with the same metal precursor.

[0174] In some embodiments, the reducing agent may be a boron- or silicon-containing reducing agent, such as B₂H₆ or SiH₄. These reducing agents can be used with metal chloride precursors or metal oxychlorides; however, B₂H₆ and SiH₄ may react with water, which forms as a byproduct during the ALD process, to form solid B₂O₃ and SiO₂. These are insulating and can remain in the film, thereby increasing resistivity. The use of NH₃ also improves adhesion on certain surfaces (including Al₂O₃) compared to ALD processes using B₂H₆ and SiH₄. The resulting nucleation layer is typically not a pure elemental film but a metal nitride or metal oxynitride film. In some embodiments, residual chlorine or fluorine from the deposition may be present, especially if the deposition is performed at low temperatures. In some embodiments, no more than trace amounts of residual chlorine or fluorine may be present. In some embodiments, the nucleation layer is an amorphous layer. Impurities in the film (e.g., oxygen, NH₃, chlorine, or other halogens) favor the growth of amorphous microstructures. In some embodiments, the deposited nucleation layer is an amorphous molybdenum oxynitride layer or an amorphous molybdenum nitride layer. The amorphous properties provide a template for the growth of large grains in the subsequently deposited conductor. The surface energy of nitrides or oxynitrides relative to oxide surfaces is much more favorable than that of metals on oxide surfaces, thus facilitating the formation of continuous and smooth films on the dielectric. This allows for the formation of thin, continuous layers. Exemplary thicknesses of the nucleation layer during deposition range from 5 Å to 30 Å. For example, depending on the temperature, this could be approximately 5 to 50 ALD cycles.

[0175] Integrated processes including etching and / or suppression Etching operations can be used in methods that fill features with a Mo film. Etching removes metal and nitride materials from the feature. For example, an etching process can remove a pad (e.g., TiN) layer from the feature, either partially or completely. In another example, an etching process can be used to reduce the thickness of the pad layer. The etching process can be performed as part of a pretreatment process described elsewhere in this disclosure, and / or as part of a deposition-etch-deposition process for etching molybdenum.

[0176] Etching agents are any compounds used to remove materials (such as layers, byproducts, or contaminants) from a surface. In some embodiments, the etchant is a halogen-containing etchant, such as chlorine (Cl2), fluorine (F2), bromine (Br2), iodine (I2), hydrogen chloride (HCl), hydrogen fluoride (HF), hydrogen iodide (HI), chlorine trifluoride (ClF3), ferric chloride (FeCl3), trifluoromethane (CHF3), fluoromethane (CH3F), octafluorocyclobutane (C4F8), hexafluorobutadiene (C4F6), hexafluorocyclopentadiene (C5F6), carbon tetrafluoride (CF4), carbon tetrafluoride (CCl4), nitrogen trifluoride (NF3), boron trichloride (BCl3), boron trifluoride (BF3), hydrogen iodide (HI), hydrogen bromide (HBr), sulfur tetrafluoride (SF4), sulfur hexafluoride (SF6), thionyl chloride (SOCl2), phosphorus pentafluoride (PF5), phosphorus trifluoride (PF3), silicon tetrabromide (SiBr4), or combinations thereof. In some embodiments, a single etchant may be sufficiently effective. In some embodiments, a combination of more than one etchant may be used. Examples of combinations include oxygen (O2) and one of the aforementioned halogenated etchants, such as chlorine and oxygen; or fluorine and oxygen. Alternatively, carbon dioxide (CO2) may be used in combination with one of the aforementioned halogenated etchants. If a combination of etchants is used, they can be flowed together (simultaneously) or sequentially (one after another) through the delivery line. The etchants may be co-flowed with an inert gas (such as argon). In some embodiments, the etchants are combined. For example, a halogenated etchant may be co-flowed with a halogen-free etchant.

[0177] In some embodiments, the etchant is MoCl5, MoF6, WF6, WCl5, or any other metal halide described above. For example, in some embodiments, the etching operation may involve immersing the feature in molybdenum halide. In some embodiments, the etching operation involves using MoCl5, such as MoCl5. x Immersion characteristics. In some embodiments, immersion can be performed continuously using molybdenum halide gas. In some embodiments, immersion can be pulsed, with molybdenum halide being circulated with a purge gas (e.g., argon (Ar)).

[0178] Molybdenum halide precursors can be used in both deposition and etching operations. For example, within a specific process window, a MoCl5 precursor can simultaneously grow a Mo film and etch away the metal or metal compound film in the feature. If the rate of material removal is greater than the rate of material deposited by the precursor, the process is considered a net etching operation. The rates of precursor deposition and etching can be controlled by various process conditions, including the type of reactants used and the process temperature. Generally, the lower the temperature, the higher the proportion of material etched relative to the material deposited. At higher temperatures, the same precursor and reactants can be used for a net deposition operation, i.e., the amount of material deposited is greater than the amount of material removed. For example, when the process temperature is below 400°C, a MoCl5 precursor and H2 reactant can be used in an etching operation. When the process temperature is above 550°C, the same MoCl5 precursor and H2 reactant can be used in a deposition operation.

[0179] In some implementations, MoCl x Precursors at high temperatures, such as above 550°C, can continue etching material at a faster rate than the deposited material. For example, MoCl5 can be used to etch features by immersion in a non-reactant solution. In this example, temperatures can reach up to 700°C and material will continue to be etched away from the feature. In operations where the feature is immersed in non-reactant MoCl5, the increased temperature may increase the rate at which material is etched away from the feature.

[0180] In some embodiments, deposition via ALD or CVD may result in deposition at the bottom of the feature and net etching at the top due to concentration differences within the feature. For example, in Figure 11, an originally unfilled feature with conformal padding 1112 is shown exposed to molybdenum precursor flow. The molybdenum precursor concentration decreases with feature depth, transitioning from an etched state at the top to a deposited state at the bottom. For example, for MoF6, the concentration at the top may be greater than 0.01%, while the concentration at the bottom may be less than 0.004%. The result is net etching at the field region of the feature and net deposition at the bottom of the feature. For deep features (e.g., features with an aspect ratio of 10:1 or higher), the concentration gradient may be caused by diffusion limitations within the feature. In some embodiments, multiple operations can be performed with different precursor concentrations.

[0181] The surface of the feature may have oxides or contaminants. For example, the surface of the underlying TiN, WN, or W layer may be oxidized. If the oxide surface remains, it will lead to higher resistivity. A cleaning operation is used to remove such oxides and contaminants. In some embodiments, the cleaning operation may involve immersion in a Mo precursor gas (typically molybdenum halide). Similar to the etching operation described above, the precursor gas may be MoCl₂. xPrecursor. In some embodiments, the soaking can be continuous. In some embodiments, the soaking can be pulsed, causing MoCl... x Alternate with purge gases (e.g., argon (Ar)). The precursor can be an oxygen-free molybdenum-containing Cl-containing compound capable of removing oxidation from the characteristic surface. MoCl x Examples of the compounds are provided above. Cl-containing precursors can be used when conventional cleaning methods using heat or plasma H2 are ineffective, such as when surface stabilization is achieved by oxidation on the surface material. Compared to F-containing compounds, Cl-containing precursors are less likely to over-etch the feature-enhancing liner or erode the feature-enhancing surface.

[0182] Etching can be thermal or plasma-enhanced. In some embodiments where material in a lateral feature is etched, thermal etching allows the etchant chemical composition to diffuse into the feature.

[0183] Suppression operations can be used in methods of filling features with Mo films. Suppression operations inhibit molybdenum nucleation on the surface. For example, suppression operations can be used to inhibit nucleation on only a portion of the feature, extending from the feature opening to a certain depth within the feature. In some embodiments, the incoming structure can be treated to suppress molybdenum nucleation. For example, a feature having dielectric sidewalls and a conductive bottom surface can be treated such that nucleation is suppressed on the upper portion of the sidewalls, thereby promoting selective deposition. This suppression treatment can be repeated during subsequent deposition to maintain its effectiveness.

[0184] Dielectric materials can be treated with halogen-containing chemicals to inhibit molybdenum nucleation. Examples include F2, NF3, BCl3, MoCl5, and Cl2. Each of these involves chlorinating or fluorinating the oxide to inhibit further nucleation.

[0185] Suppression operations can also be performed as part of a deposition-suppression-deposition (DID) technique. In some embodiments, a portion of the molybdenum film is treated to suppress subsequent deposition. Examples of suppression chemicals include nitrogen-containing chemicals (including N2 and NH3) and halide-containing chemicals (such as alkyl halides). For example, inhibitors such as N2 can co-flow with the molybdenum precursor and / or H2. Suppression can be a plasma or thermal operation. If a plasma operation is used, remote or direct plasma can be used. Other examples of suppression operations may include exposure to oxygen-, carbon-, and phosphorus-containing thermal or plasma chemicals. In some embodiments where material in a lateral feature is etched, thermal suppression allows suppression chemicals to diffuse into the feature.

[0186] As described above, alkyl halides can be used to suppress nucleation on molybdenum-containing surfaces for DID operations, and to modify other surfaces, including metal nitrides such as TiN. In some embodiments, the halogen-containing compound is an alkyl halide (e.g., a tertiary alkyl halide, such as tert-butyl chloride or tert-butyl iodide). In some embodiments, the halogen-containing compound is an iodine-containing compound. Other examples of inhibitors include trimethylsilyl chloride [(CH3)3SiCl] and trimethylsilyl dicarboxamide [(CH3)3SiN(CH3)2]. Chlorine (Cl2) is an etchant and can also inhibit growth on molybdenum. Inhibition has been observed at substrate temperatures of approximately 450°C to 600°C for non-plasma exposure to Cl2.

[0187] Desuppression operations can be used to reduce the suppression effect before or after subsequent deposition. This can be used to further refine the fill profile. Examples of desuppression operations include H2 immersion, NH3 immersion, and H2 plasma exposure. Immersion operations can be continuous flow or pulsed.

[0188] This article also provides deposition-etch-deposition (DED) and deposition-inhibition-deposition (DID) techniques. These can be used to modulate deposition within features during interconnect metallization (as described above) and are suitable for memory applications. Figure 12 shows examples of DED and DID processes on vertically oriented features, for example, for logic applications. For the DED process, the deposited Mo film is preferentially etched off the top of the feature or near the field region. This produces a tapered profile. Subsequent deposition is performed without closing the feature. For the DID process, the field region and the top of the feature are preferentially inhibited, allowing molybdenum to be deposited at the bottom of the feature.

[0189] The DED operations described herein can be used in logic applications, such as interconnects and memory applications. The use of DED technology to fill 3D NAND structures will be further described below. In some implementations, multiple DED operations are used to fill features. The same or different chemicals can be used for each deposition. The molybdenum precursor can be a molybdenum halide or molybdenum oxyhalide as described above, or a molybdenum organometallic precursor. The same or different chemicals can be used for each etching operation.

[0190] During etching, anisotropic etching can be achieved using high flow rates and short dose times. As mentioned above, pretreatment can be used to increase the etching rate and refine the etching profile. For example, anisotropic oxidation or nitriding may be performed before etching. This helps to etch only the top of the feature (for vertical features) or the outside of the feature (e.g., the outer word line in a 3D NAND structure). Examples of oxidation operations include exposure to O2 or O3 or oxygen-containing plasma. Examples of nitriding operations include exposure to NH3 or N2 or nitrogen-containing plasma. Posttreatment can be used to remove impurities after etching. For example, exposure to halosilanes can be used to remove fluorine or chlorine. Exposure to H2 can be used to remove impurities. Depending on various embodiments, posttreatment can be performed after each dose of the etchant or less frequently, for example, at the end of multiple cycles including etching.

[0191] In some embodiments, the DED sequence may include one or more suppression operations. Suppression operations are those that inhibit molybdenum film nucleation or formation during subsequent deposition. They can be used to adjust the deposition profile. Examples of suppression chemicals include nitrogen-containing chemicals (including NF3, N2, and NH3) and halide-containing chemicals (such as alkyl halides, B2H6, and Cl2). For example, inhibitors such as N2 can co-flow with molybdenum precursors and / or H2. Suppression can be plasma- or thermally operated.

[0192] Deinhibition operations can be used to reduce inhibition effects before or after subsequent deposition. This can be used to further refine the fill profile. Examples of deinhibition operations include H2 immersion, NH3 immersion, and H2 plasma exposure. Immersion operations can be continuous flow or pulsed. Extending the preparation time of precursors and / or reactants after inhibition treatment can also be used to reduce or eliminate inhibition effects.

[0193] A process can be tuned for fill using various arrangements of deposition 1, deposition 2, etching, suppression, and desuppression operations. Examples of process sequences include: Deposition—Etching—Deposition Deposition—Inhibition—Deposition Deposition—Etching (x)—Inhibition (y)—Deposition Deposition—Etching (x)—Inhibition (y)—Deposition—Desuppression—Deposition Deposition—Inhibition—Etching—Deposition Deposition—Etching—Deposition—Inhibition—Deposition Deposition—Etching—Deposition—Inhibition—Deposition—Deinhibition—Deposition Deposition—Inhibition—Deposition—Etching—Deposition Deposition—Oxidation—Etching—Deposition Deposition—nitriding—etching—deposition In some implementations, the deposition-etch-deposition operation disclosed herein can be integrated into a single-chamber metallization process as described above.

[0194] In some implementations, a simultaneous DED process can be performed. This may also be referred to as a hybrid DED process. Figure 13 is a flowchart illustrating a method of hybrid deposition and etching according to some disclosed embodiments. This method can be described as hybrid deposition and etching because the reducing agent and etchant are introduced into the processing chamber simultaneously. In some implementations, the simultaneous supply of the two reagents can be completely simultaneous when the reducing agent and etchant flow into the processing chamber for the same duration. As used herein, “simultaneously” or “occurring simultaneously” refers to the time interval or duration of reagent delivery or flow at the same time. “Completely simultaneous” means that one reagent is delivered for a first duration and another reagent is delivered for a second duration, wherein the overlap between the two durations is 95–100%. “Partially simultaneous” means that one reagent is delivered for a first duration and a second reagent is delivered for a second duration, wherein the second duration is during the first duration but shorter than the first duration. In Figure 13, operation 1302 is the introduction of a molybdenum-containing precursor into the processing chamber containing the semiconductor substrate. Operation 1304 is an optional purging step. Operation of the purging chamber may involve flowing a purging gas or sweep gas, which may be a carrier gas used in other operations or a different gas. In some embodiments, purging may involve venting the chamber. Examples of purging gases include argon (Ar), nitrogen (N2), hydrogen (H2), helium (He), oxygen (O2), krypton (Kr), xenon (Xe), neon (Ne), and combinations thereof. In various embodiments, the purging gas is an inert gas. The purging gas may include one or more gases. In some embodiments, operation 1304 may include one or more venting sub-stages for venting the processing chamber. Alternatively, it should be understood that purging may be omitted in some embodiments. In some embodiments, increasing the flow rate of one or more purging gases may reduce the duration of purging. For example, the purging gas flow rate may be adjusted based on various reactant thermodynamic and / or geometric properties of the processing chamber and / or processing chamber piping to modify the duration of purging. In a non-limiting example, the duration of the purging stage may be adjusted by modulating the purging gas flow rate. This may shorten the deposition cycle time, thereby increasing substrate yield. In operation 1306, at least one etchant and at least one reducing agent are introduced into the processing chamber. When used herein, "simultaneously" or "occurring at the same time" refers to the time interval or duration during which reagents are delivered or flowed at the same time. As shown in operation 1306, in some embodiments, the time interval or duration of etchant delivery and reducing agent delivery is the same. Although the etchant and reducing agent are delivered at the same time, they may each be delivered at different flow rates. In other embodiments, the reducing agent may flow into the processing chamber before, after, or before and after the introduction of the etchant. Thus, the flow of the reducing agent and the flow of the etchant are partially simultaneous. Alternatively, the reducing agent may be introduced in a pulsed manner during etchant delivery.Furthermore, the concentration of the etchant can remain constant or vary (i.e., gradually increase or decrease) throughout its delivery duration. The ratio of reducing agent to etchant can be adjusted to achieve the desired results or properties of the deposited film. These include, but are not limited to, deposition rate, uniformity, resistivity, thickness, and step coverage within features. This adjustment can also be used to adjust the wafer-wide uniformity of these properties. In some embodiments, the ratio of reducing agent to etchant is from about 10,000:1 to about 10:1. The etchant flow rate, concentration, and ratio can be the same in each cycle or can be adjusted independently between different cycles.

[0195] The reducing agent is typically a reducing gas. Suitable examples of reducing agents include H2, SiH4, NH3, or B2H6. In some embodiments, the reducing agent may be in the form of plasma, such as hydrogen plasma. In some embodiments, the reducing agent is hydrogen, ammonia, hydrazine, silane, disilane, trisilane, germanane, digermanane, diborane, or combinations thereof.

[0196] The flow rate of the etchant typically depends on the chamber size, etching rate, etching uniformity, and other parameters. These are usually much lower than the flow rate of the reducing agent.

[0197] In some embodiments, the etchant or etchant combination is halogen-containing, and the halogen of the etchant in operation 1306 is the same as the halogen substituent on the metal halide precursor used in operation 1302. For example, a molybdenum precursor including MoO2Cl2 or MoCl5 can be used in combination with a chlorine-containing etchant (such as HCl / Cl2); or a fluorine-containing molybdenum precursor (such as MoF6) can be used in combination with a fluorine-containing etchant (such as HBr / HF / F2). The selection of a common halogen for both the etchant and the precursor can be used to enhance etching at the top surface and upper sidewalls of the feature; overcoming any formation problems of overhangs in the breadstick structure near the feature opening. The breadstick structure or breadstick-like structure can also be referred to as a bottleneck. Furthermore, choosing a reducing agent (such as hydrogen) in combination with a halogen-containing etchant may be advantageous because the reactive material of the halogen-containing etchant may be relatively heavier atomically than the reactive material of hydrogen. This induces the reactive material of the halogen-containing etchant to remain near the feature opening and preferentially etch therein. When using this combination, top-heavy etching (i.e., the etchant etches more near the opening than at the bottom of the feature) mixed with deposition results in superconformal deposition of metal, thereby improving gap filling.

[0198] Operation 1308 is a second optional cleaning step. In process 1300, either cleaning 1304 or 1308 may be included; both cleaning 1304 and 1308 may be included; or cleaning may not be used.

[0199] In operation 1310, it is determined whether the deposited metal has the desired thickness. If a thicker film is desired, then operation 1312 is the process flow path, indicating that after operation 1306, operation 1302 can be started again and repeated. n Next. In process flow path 1312, n This refers to the number of cycles, which can be 1 to 50 or 20 to 40. The cycles of operations 1302 and 1306, as well as the optional sweep 1304, can be repeated as needed. The term "cycle" as used herein refers to a specific sequence of operations. Sufficient thickness can result in the feature being fully or partially filled.

[0200] Deposition-etching-deposition for 3D NAND word line filling As described above, the methods described herein can be used to fill 3D NAND structures. Figure 14 is a process diagram showing operations in the DED method for filling word line features of a 3D NAND structure. Figure 15A depicts some operations of the process of Figure 14. The method of Figure 14 begins in operation 1401 by providing a 3D NAND structure with unfilled word line features. Examples of such structures have previously been described with reference to Figures 2F-2J. Figure 15A shows a top-down view of the pillars of a partial example of a 3D NAND structure. The outer pillars are adjacent to slits from which fluid can flow into the word line features. In the described example, three rows of staggered pillars are shown. Depending on various embodiments, the number of rows can be, for example, 20 or more. As described above with reference to Figure 2F, there are slits on both sides, such that reaching the innermost word line of the 20 rows of pillars involves diffusion from the slits through 10 rows of pillars. Referring back to Figure 2F, the critical dimensions of the central vertical structure 230 are likely on the order of hundreds of nanometers, with a depth exceeding 1 micrometer. The critical dimensions of word line features prior to molybdenum deposition may be, for example, 10-20 nm or 12-16 nm. As mentioned earlier, uniformly and pore-free filling of these features can be challenging. Substrates incorporating 3D NAND structures can be provided to semiconductor processing tools. When provided, the pillars may include a dielectric layer, such as an Al2O3 layer as shown in Figure 15A.

[0201] Returning to Figure 14, the method includes depositing conformal pads and thin films in word line features of a 3D NAND structure in operation 1403. An example of a conformal pad + film is shown in the left illustration of Figure 15A. As shown, Mo is conformally deposited around the various features, uniformly deposited from the outside (slit side) to the inside (non-slit side). This partially filled deposition can be referred to as Deposition 1 operation. In some embodiments, the conformal pad and thin film deposition can be a single film, which is the result of multiple cycles of a single ALD process for depositing a conformal film of about 4 nm to 6 nm. However, in some embodiments, a nucleation layer is deposited. This can be referred to as a pad layer. For example, molybdenum does not nucleate well on Al2O3 or other oxide surfaces. The nucleation layer can be deposited as described above. In some embodiments, ammonia is used as a reducing agent to deposit a molybdenum nitride or molybdenum oxynitride pad layer of less than 2 nm. This allows subsequent processes using hydrogen as a reducing agent to deposit on the pad layer to increase the total thickness, for example, to about 4 nm to 6 nm. Molybdenum nitride or molybdenum oxynitride layers are converted to molybdenum during the Mo-containing precursor / H2ALD process. The thickness of the pad layer and the pad + film layer can be modified according to the size of the structure. The ALD process in Figure 14 is typically a thermal ALD process. This is because it is easier to achieve lateral filling throughout the word line feature using heat treatment. Conformal filling throughout complex structures is also facilitated by using molybdenum oxyhalide precursors (such as MoO2Cl2) instead of molybdenum halides (such as MoCl5). This is because molybdenum halides are stronger etchants. In the case of large and complex structures, molybdenum halides may etch at the top of the structure while the precursor diffuses through the structure.

[0202] In some embodiments, a thermal ALD process using MoO2Cl2 and NH3 is used to deposit conformal gaskets at temperatures ranging from 350°C to 550°C. In other embodiments, a thermal ALD process using MoO2Cl2 and H2 is used to deposit conformal films on the gaskets at even higher temperatures (e.g., 550°C to 615°C). To achieve top-down and lateral uniformity, charge volumes can be used for precursor and / or reducing agent doses.

[0203] Optional etching pretreatment can be performed in operation 1405. Pre-etching makes it easier to etch in subsequent operations. If performed, the pre-etching treatment can be conformal or non-conformal. In some embodiments, it is non-conformal, preferentially applied to outer word lines relative to inner word lines. The pre-etching treatment may be molybdenum oxidation or nitriding. The pre-etching treatment can be plasma or thermal treatment. In some embodiments, thermal pre-etching may allow for easier control of diffusion and the extent of treatment within the structure.

[0204] For oxidation, the structure can be exposed to ozone. Furthermore, due to the relatively high temperatures (e.g., 450°C to over 600°C), exposure to oxygen (O2) or water vapor may be used. For nitriding, ammonia or another nitrogen-containing gas or plasma can be used. Operation 1405 exhibits top-to-bottom homogeneity. Similar to operation 1403, this homogeneity can be achieved using a filling volume.

[0205] Following an optional pre-etching process, etching with a preference for molybdenum in the outer word lines is performed in operation 1407. At the outer portions of the word line features, the oxide of the features may be exposed. The inner portions of the word lines may be etched less, allowing molybdenum to remain on the inner features. This is depicted in the intermediate illustration of Figure 15A, where molybdenum on the outermost pillars is removed, most of the molybdenum in the second row of pillars is removed, and the molybdenum on the third row of pillars remains intact. In some embodiments, the molybdenum is thinned but not completely removed from any portion of the word line features.

[0206] The degree of etching can be determined based on the number of pillars, the geometry of the structure, and so on. For example, a first etching can be designed to remove molybdenum from all pillars except the innermost one, while subsequent etchings will retain molybdenum on the next innermost row, and so on. Pre-etching can be used to adjust the etching profile. In addition to or instead of pre-etching, the concentration of the etchant and / or the dosing time can be used to control the degree of diffusion and etching into the structure. Chamber pressure and substrate temperature are other parameters that can be varied to adjust the etching profile. Chamber pressure is used to control the diffusion of chemicals, and temperature is used to control the reactivity of chemicals with the Mo surface.

[0207] Higher etchant concentrations (and therefore higher partial pressures) can be used to penetrate deeper into the structure. Similarly, continuous feeding or longer pulsed feeding times will promote diffusion. Lower partial pressures and / or shorter etchant feeding times can be used to prevent further diffusion of the etchant into the structure. Top-to-bottom uniformity can be achieved using filling volume. Examples of etching process states include pressure ranges from 100 mT to 100 T, temperatures from room temperature to 750 °C, gas flow rates from 50 sccm to 50 slm, feeding times from 10 ms to 60 s, and etchant concentrations from 0.001% to 100%.

[0208] Examples of etching chemicals include halogenated compounds such as MoCl5, F2, NF3, MoF6, BCl3, HCl, Cl2, ClF3, Cl2O, SF6, CF4, HF, HBr, WF6, and CCl4. For 3D NAND structures, etching is a thermal etching process to avoid plasma damage. However, aspects of the method described in Figure 14 can be applied to logic applications that may use plasma etching. An optional post-etching treatment can be performed in operation 1409. This treatment can be used to remove byproducts that may hinder subsequent etching and / or are undesirable in the device. For example, any oxygen, chlorine, or boron can be removed. Post-etching treatments may involve reducing immersion (e.g., H2 immersion) or exposure to halosilanes, for example, to perform ligand exchange. Other examples include exposure to argon.

[0209] Returning to Figure 14, a thin film is deposited via ALD in operation 1411. Typically, the same precursor and process range used as in the conformal film in operation 1403 are employed. Different precursors or process ranges may be used. This may be referred to as the Deposition 2 operation. In embodiments where the oxide is exposed during etching of the feature exterior, deposition can be selective for the molybdenum film retained on the word line feature. Thus, the film deposited in subsequent depositions may be selectively deposited relative to the inner portion of the word line feature. As molybdenum begins to grow and nucleation delay is overcome (if present), the deposition may become conformal. As shown in Figure 15A, after subsequent deposition, the Mo film may be thicker on the inner portion of the feature compared to the outer portion. In embodiments without nucleation delay, the Mo film may be thicker on the inner portion of the feature compared to the larger thickness of the outer portion after etching. The right-hand illustration of Figure 15A shows the structure after the Deposition 2 operation. In some embodiments, the aforementioned pad or other nucleation layer may be part of the Deposition 2 operation.

[0210] Operations 1405-1411 can be repeated once or more to further fill the structure. For any two repetitions, the pretreatment, etching, post-treatment, and deposition operating conditions can be different or the same. For example, the etching in subsequent iterations can be adjusted to extend to a smaller depth within the structure.

[0211] In some embodiments, MoO2Cl2 is used for partial filling of deposition 1 and selective deposition of deposition 2. In other embodiments, other molybdenum precursors may be used, and deposition 1 and deposition 2 may use the same or different precursors. The suppression and desuppression operations described above can be incorporated into the integrated process described above.

[0212] In some embodiments, the deposition-etch-deposition operations disclosed herein can be integrated into a single-chamber metallization process as described above. Figure 15B shows an example of possible operations. In other embodiments, any one or more operations can be performed in different chambers. In some embodiments, these chambers can be connected by vacuum.

[0213] In Figure 15B, conformal pads and films can be deposited using ALD. As mentioned above, the pads can be molybdenum oxynitride or molybdenum nitride layers deposited using molybdenum oxyhalides and ammonia. A host molybdenum film can be deposited on the pads using molybdenum oxyhalides and hydrogen. Anisotropic etching can be performed using optional thermal or plasma pretreatment and / or post-treatment. Similarly, anisotropy suppression can be performed using heat or plasma.

[0214] For final filling, a host molybdenum film can be deposited using molybdenum oxyhalide and hydrogen ALD processes. Multiple DED (or DEID, etc.) operations can be performed to optimize gap filling. A capping process can be performed using ALD or CVD to deposit molybdenum on the sidewalls of the central vertical structure.

[0215] Device Figure 16 illustrates a schematic diagram of an embodiment of an ALD processing station 1600 having a processing room 1602 for maintaining a low-pressure environment. In some embodiments, multiple ALD processing stations may be contained within a common low-pressure processing tool environment. For example, Figures 17A and 17B depict an embodiment of a multi-station processing tool 1700. In some embodiments, one or more hardware parameters of the ALD processing station 1600, including those discussed in detail below, may be programmatically adjusted by one or more computer controllers 1750. In other embodiments, the processing room may be a single-station room.

[0216] ALD processing station 1600 is in fluid communication with reactant delivery system 1601a to deliver process gas to distribution nozzle 1606. Reactant delivery system 1601a includes mixing container 1604 for mixing and / or conditioning process gases, such as Mo-containing precursor gases, hydrogen-containing gases, argon or other carrier gases, or other reactant-containing gases, to be delivered to nozzle 1606. One or more mixing container inlet valves 1620 can control the introduction of process gas into mixing container 1604. In various embodiments, the initial Mo layer deposition occurs in processing station 1600, and in some embodiments, other operations such as in-situ cleaning or Mo gap filling may be performed at the same or another station of multi-station processing tool 1700, as further described below with reference to Figure 17A.

[0217] As an example, the embodiment of Figure 16 includes a vaporization point 1603 for vaporizing liquid reactants to be supplied to mixing vessel 1604. In some embodiments, vaporization point 1603 may be a heated vaporizer. In some embodiments, the liquid precursor or liquid reactant may be vaporized at a liquid injector (not shown). For example, the liquid injector may pulse the liquid reactant into a carrier gas flow upstream of mixing vessel 1604. In one embodiment, the liquid injector may vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another example, the liquid injector may atomize the liquid into dispersed microdroplets that are subsequently vaporized in a heated delivery tube. Smaller droplets vaporize faster than larger droplets, thereby reducing the delay between liquid injection and completion of vaporization. Faster vaporization can reduce the pipe length downstream of vaporization point 1603. In one embodiment, the liquid injector may be directly mounted to mixing vessel 1604. In another embodiment, the liquid injector may be directly mounted to nozzle 1606.

[0218] The reactant delivery system 1601a may also include one or more solid precursor delivery components, including one or more onboard ampoules 1613 and / or batch delivery components 1615. Figure 18 below provides an example of a batch delivery system.

[0219] In some embodiments, a liquid flow controller (LFC) can be positioned upstream of the vaporization point 1603 to control the mass flow rate of the liquid used for vaporization and delivered to the processing chamber 1602. For example, the LFC may 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 electrically communicating with the MFM. However, it may take one second or more to use feedback control to stabilize the liquid flow. This can prolong the time for dispensing the liquid reactants. Therefore, 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 pipe and PID controller of the LFC.

[0220] Nozzle 1606 dispenses process gas toward substrate 1612. In the embodiment shown in FIG. 16, substrate 1612 is located below nozzle 1606 and is shown as being mounted on base 1608. Nozzle 1606 may have any suitable shape and may have any suitable number and arrangement of ports for dispensing process gas to substrate 1612.

[0221] In some embodiments, the base 1608 can be raised or lowered to expose the substrate 1612 to the volume between the substrate 1612 and the nozzle 1606. In some embodiments, the base 1608 can be temperature-controlled by a heater 1610. The base 1608 can be set to any suitable temperature during operation for performing the various disclosed embodiments, such as between about 250°C and about 800°C. It should be understood that in some embodiments, the base height can be adjusted programmatically via a suitable computer controller 850. At the end of a processing phase, the base 1608 can be lowered during another substrate transfer phase to allow removal of the substrate 1612 from the base 1608.

[0222] In some embodiments, the position of the nozzle 1606 can be adjusted relative to the base 1608 to change the volume between the substrate 1612 and the nozzle 1606. Furthermore, it should be understood that the vertical position of the base 1608 and / or the nozzle 1606 can be changed by any suitable mechanism within the scope of this disclosure. In some embodiments, the base 1608 may include a rotation axis for rotating the orientation of the substrate 1612. It should be understood that in some embodiments, one or more of these exemplary adjustments can be performed programmatically by one or more suitable computer controllers 1650. The computer controller 1650 may include any of the features described below with respect to the controller 1650 of FIG. 16.

[0223] In some embodiments where plasma can be used as described above, nozzle 1606 and base 1608 are electrically connected to radio frequency (RF) power supply 1614 and matching network 1616 to power the plasma. In some embodiments, the energy of the plasma can be controlled by controlling one or more of the following: processing station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, RF power supply 1614 and matching network 1616 can operate at any suitable power to form a plasma with the desired free radical composition. Similarly, RF power supply 1614 can provide RF power at any suitable frequency. In some embodiments, RF power supply 1614 can be configured to control a high-frequency RF power supply and a low-frequency RF power supply that are independent of each other. Exemplary low-frequency RF frequencies may include, but are not limited to, frequencies between 0 kHz and 900 kHz. Exemplary high-frequency RF frequencies may 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 parameter can be adjusted discretely or continuously to provide plasma energy for surface reactions.

[0224] In some embodiments, the plasma can be monitored in situ by one or more plasma monitors. In one case, plasma power can be monitored by one or more voltage and current sensors (e.g., VI probes). In another case, plasma density and / or process gas concentration can be measured by one or more optical emission spectrometers (OES). In some embodiments, one or more plasma parameters can be programmed to adjust based on measurements from such in-situ plasma monitors. For example, OES sensors can be used in feedback loops to provide programmable control of plasma power. It should be understood that in some embodiments, other monitors can be used to monitor plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure sensors.

[0225] In some implementations, instructions for the controller 1650 can be provided via input / output control (IOC) sequencing instructions. In one example, instructions for setting conditions for a process stage can be included in the corresponding formulation stage of the process formulation. In some cases, process formulation stages can be arranged sequentially such that all instructions for a process stage are executed simultaneously with that process stage. In some implementations, instructions for setting one or more reactor parameters can be included in the formulation stage. For example, a first formulation stage may include instructions for setting the flow rate of an inert gas and / or reactant gas (e.g., a Mo precursor), instructions for setting the flow rate of a carrier gas (e.g., argon), and time delay instructions for the first formulation stage. A subsequent second formulation stage may include instructions for adjusting or stopping the flow rate of the inert gas and / or reactant gas, instructions for adjusting the flow rate of a carrier gas or purge gas, and time delay instructions for the second formulation stage. A third formulation stage may include instructions for adjusting the flow rate of a second reactant gas, such as H2, instructions for adjusting the flow rate of a carrier gas or purge gas, instructions for igniting the plasma, and time delay instructions for the third formulation stage. The subsequent fourth formulation stage may include instructions for adjusting or stopping the flow rates of the inert gas and / or reactant gas, instructions for adjusting the flow rates of the carrier gas or purge gas, and instructions for a time delay for the fourth formulation stage. It should be understood that, within the scope of this disclosure, these formulation stages may be further subdivided and / or repeated in any suitable manner.

[0226] Furthermore, in some embodiments, pressure control for processing station 1600 may be provided by butterfly valve 1618. As shown in the embodiment of Figure 16, butterfly valve 1618 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of processing station 1600 may also be adjusted by changing the flow rate of one or more gases introduced into processing station 1600.

[0227] Figures 17A and 17B show examples of processing systems. Figure 17A shows an example of a processing system comprising multiple chambers. System 1700 includes a transfer module 1703. The transfer module 1703 provides a clean, vacuum environment to minimize the risk of contamination during substrate movement between various modules while being processed. Mounted on the transfer module 1703 is a multi-station chamber 1709 capable of performing the aforementioned in-situ cleaning and / or ALD processes. Surface treatment and / or initial Mo layer deposition can be performed in the same or different stations or chambers as subsequent Mo interstitial filling.

[0228] Chamber 1709 may include multiple stations 1711, 1713, 1715, and 1717, which may sequentially perform operations according to the disclosed embodiments. For example, chamber 1709 may be configured such that station 1711 uses MoCl x Precursor preparations are used to perform in-situ processing. Station 1713 can be configured to selectively process the field region and upper sidewalls, and stations 1715 and 1717 can be configured to perform ALD of the host Mo using a molybdenum halide precursor and H2. In another example, chamber 1709 can be configured such that station 1711 performs in-situ cleaning, station 1713 performs ALD of the initial Mo layer, station 1713 selectively processes the layer, and station 1714 deposits the host Mo. In yet another example, chamber 1709 can be configured to perform parallel substrate processing, where each station sequentially performs multiple processes.

[0229] Two or more stations can be included in a multi-station chamber, such as 2-6, and the operation is appropriately distributed. For example, a two-station chamber can be configured to perform ALD of the initial Mo layer in the first station, followed by ALD of the bulk Mo in the second station. A station may include a heating base or substrate support, one or more gas inlets, or nozzles, or dispersion plates.

[0230] One or more single-station or multi-station modules 1707 may also be mounted on the transfer module 1703. In some embodiments, pre-cleaning as described above can be performed in module 1707, after which the substrate is transferred under vacuum to another module for ALD (e.g., another module 1707 or chamber 1709). In another example, a module for selectively processing the film may be mounted on the transfer module. Figure 10 shows an example.

[0231] System 1700 also includes one or more wafer source modules 1701, which store wafers before and after processing. An atmospheric robot (not shown) in atmospheric transfer chamber 1719 can first move wafers from source modules 1701 to loading locks 1721. A wafer transfer device (typically a robotic arm unit) in transfer module 1703 moves wafers from loading locks 1721 to modules mounted on transfer module 1703 and moves wafers between them.

[0232] For example, referring to Figures 6A and 6B, in some embodiments, chamber 1709 is configured to perform pretreatment, selective filling, conformal pad deposition, and final filling. In one example, station 1711 is configured to perform pretreatment, station 1713 is configured to perform selective filling, station 1714 is configured to perform conformal pad deposition, and station 1715 is configured to perform final filling. In some embodiments, etching and / or suppression processes may be performed. For example, station 1711 is configured to perform pretreatment, station 1713 is configured to perform selective filling, station 1714 is configured to perform suppression, and station 1715 is configured to perform final filling. Similarly, chamber 1709 may be configured to perform all the processes described in Figures 6C-6F and Figure 15B.

[0233] Chamber 1709 may have one or more of the following features to enable single-chamber metallization processes: Individually addressable plasma power generators associated with each station; Individually addressable reactant inputs associated with each station; Multi-chamber nozzles at each station; Dual solid precursor delivery system.

[0234] Solid precursor delivery systems may include batch delivery systems and / or onboard ampoules. Figure 18 below provides an example of a solid precursor delivery system that can be employed.

[0235] Figure 17B illustrates an embodiment of system 1700. System 1700 in Figure 17B includes a wafer source module 1701, a transfer module 1703, an atmospheric transfer chamber 1719, and a loading lock 1721, as described above with reference to Figure 17A. The system in Figure 17B has three single-station modules 1757a-1775c. System 1700 can be configured to sequentially perform operations according to the disclosed embodiment. For example, single-station modules 1757a-1757c can be configured such that the first module 1757a performs surface treatment, the second module 957b performs ALD of the initial Mo layer using a molybdenum halide precursor, and the third module 957c performs ALD of the host Mo using a molybdenum halide oxide precursor. In this example, instead of pre-cleaning in or attached to the first module 1757a, in-situ cleaning may optionally be performed in the second module 1757b. In another example, single-station modules 1757a-1757c can be configured such that the first module 1757a performs the deposition of an initial metal layer, the second module 1757b performs selective processing, and the third module 1757c performs ALD of the host Mo using a molybdenum halide precursor. In yet another example, one module can be configured for deposition, another for selective processing, and another for etching.

[0236] The station may include a heating base or substrate support, one or more gas inlets or nozzles or diffusers, as described above with reference to FIG16.

[0237] Referring back to Figures 17A and 17B, in various embodiments, a system controller 1729 is employed to control process conditions during deposition. The controller 1729 will typically 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, etc. Such a system controller can be used to control any of the processes and apparatus described herein.

[0238] The controller 1729 controls the activities of all devices. The system controller 1729 runs system control software, which includes a set of instructions for controlling timing, gas mixing, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other process-specific parameters. In some embodiments, additional computer programs stored on memory devices associated with the controller 1729 may be used.

[0239] Typically, a user interface will be associated with the controller 1729. The user interface may include a display screen, a graphical software display of the device and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0240] The system control logic can be configured in any suitable manner. Generally, this logic can be designed or configured in hardware and / or software. Instructions for controlling the drive circuitry can be hard-coded or provided as software. These instructions can be provided through "programming." Such programming is understood to include any form of logic, including hard-coded logic in digital signal processors, application-specific integrated circuits (ASICs), and other devices with specific algorithms implemented in hardware. Programming is also understood to include software or firmware instructions executable on a general-purpose processor. The system control software can be encoded in any suitable computer-readable programming language.

[0241] The computer program code used to control the Mo precursor pulse, hydrogen pulse, and argon flow in the process sequence, along with other processes, can 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 a processor to perform the tasks identified in the program. Also, as indicated, the program code can be hard-coded.

[0242] The 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 can be entered using a user interface.

[0243] Signals used for monitoring the process can be provided via analog and / or digital input connections to the system controller 1729. Signals used for controlling the process are output via analog and digital output connections to the deposition unit.

[0244] The system software can be designed or configured in many different ways. For example, multiple chamber assembly subroutines or control targets can be written to control the operation of the chamber assembly required to perform the deposition process according to the disclosed embodiment. Examples of programs or program segments used for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0245] In some embodiments, controller 1729 is part of a system that may be part of the embodiments described above. Such systems include semiconductor processing apparatuses that 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 may be integrated with electronics to control their operation before, during, or after the processing of a semiconductor wafer or substrate. The electronics may be referred to as a “controller” that controls various components or sub-sections of one or more systems. Depending on the processing requirements and / or the type of system, controller 1729 may be programmed to control any of the processes disclosed in this invention, including controlling the delivery of process 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, plasma pulse frequency settings, fluid delivery settings, position and operation settings, wafer loading / unloading tools and other transfer tools, and / or the transfer of loading locks connected to or interfaced with a particular system.

[0246] In a broad sense, a controller can be defined as an electronic device with 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 may include a chip storing program instructions in firmware form, 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). Program instructions may be instructions delivered to the controller or system in various settings (or program files) that define operating parameters for specific processes on or for semiconductor wafers. In some embodiments, these operating parameters may be part of a recipe defined by a process engineer to perform one or more processing steps in the fabrication of one or more layers, materials, metals, oxides, silicon, silica, surfaces, circuits, and / or bare dies of a wafer.

[0247] In some implementations, controller 1729 may be part of or coupled to a computer integrated with, coupled to, or network-connected to the system or a combination thereof. For example, controller 1729 may be in the “cloud” or be a whole or part of a fab mainframe computer system, allowing remote access to wafer processing. The computer may 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 processing steps to follow the current process, or start a new process. In some embodiments, the remote computer (e.g., a server) may provide process recipes to the system via a network, which may include a local network or the Internet. The remote computer may 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 specifying parameters for each processing step to be performed during one or more operations. These parameters may be specific to the type of process to be performed and the type of tool, to which the controller is configured to connect to or control. Therefore, as described above, the controller can be distributed, for example, by comprising one or more discrete controllers connected together via a network and working toward 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 located indoors that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer), which together control the processes within the indoor environment.

[0248] Exemplary systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, rotary rinsing chambers or modules, metal plating chambers or modules, cleaning chambers or modules, chamfering edge etching chambers or modules, PVD chambers or modules, CVD chambers or modules, ALD chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, orbital chambers or modules, and any other semiconductor processing systems that may be associated with or used in the preparation and / or manufacture of semiconductor wafers.

[0249] As described above, depending on one or more processing steps the tool is to perform, the controller may 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 plant, a host, another controller, or tools used in material handling that move wafer containers to and from tool locations and / or loading ports within the semiconductor manufacturing plant.

[0250] Controller 1729 may include various programs. A substrate positioning program may include program code for controlling chamber components used to load the substrate onto a pedestal or chuck and controlling the spacing between the substrate and other chamber components, such as gas inlets. A substrate tilting and rotation program may be included for tilting and rotation. A process gas control program may include code for controlling gas composition, flow rate, pulse duration, and optionally for allowing gas to flow into the chamber prior to deposition to stabilize the pressure within the chamber. A pressure control program may include code for controlling the pressure within the chamber by adjusting, for example, a throttle valve in the chamber's exhaust system. A heater control program may include code for controlling the current of a heating unit used to heat the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas, such as helium, to the wafer chuck.

[0251] Examples of chamber sensors that can be monitored during the deposition process include mass flow controllers, pressure sensors such as pressure gauges, and thermocouples located in a base or chuck. Appropriately programmed feedback and control algorithms, along with data from these sensors, can be used to maintain the required process conditions.

[0252] Figure 18 illustrates exemplary precursor delivery systems according to various implementations. The precursor delivery system 1800, also referred to herein as system 1800, includes an ampoule 1802 configured to have a precursor 1804 (shown in crosshairs), and to heat the precursor 1804 to vaporize it and generate precursor vapor in the headspace 1806 of the ampoule 1802. The ampoule includes an inlet 1808 and an outlet 1810. The inlet 1808 is configured to receive an inert gas from an inert gas source 1812. The inert gas and precursor vapor in the headspace of the ampoule form a mixture, which flows out from the outlet 1810. In some implementations, as shown in Figure 18, the pressure in ampoule 1802 can be maintained or controlled by a pressure-flow control element, which may include a controller and / or a flow control valve 1814. In some implementations, the pressure control valve 1814 may be a throttle valve. When the mixture of inert gas and precursor vapor flows out from outlet 1810, the pressure-flow control element of the ampoule allows inert gas to flow into ampoule 1802 through inlet 1808 to maintain the pressure in ampoule 1802. The ampoule also includes an inlet valve 1816 configured to control the flow rate of inert gas into the ampoule; an outlet valve 1818 configured to control the flow rate out from outlet 1810; and a bypass valve 1820 through which inert gas can flow downstream of ampoule 1802 without flowing through ampoule 1802.

[0253] Ampoule 1802 is located in a location within the manufacturing facility (e.g., "sub-fab") that differs from the location of the semiconductor processing tools and the processing modules to which the mixture flows. For example, the semiconductor processing tools might be located on a manufacturing floor, at a different height within the facility than the ampoule. The different locations of the ampoule and the semiconductor processing tools / processing modules are indicated by vertical dashed lines.

[0254] A mixture of precursor vapor and inert gas is configured to flow from outlet 1810 and into multiple flow paths, which are configured to direct the mixture into multiple processing modules and into the process volumes of each processing module. These flow paths extend from the location of the ampoule (e.g., in the lower layer of the wafer fab) to another location where the processing tool and / or module is located (e.g., on a wafer fab floor). System 1800 of Figure 1 includes four flow paths 1822A-D, each crossing from the ampoule location (e.g., in the lower layer of the wafer fab) to the corresponding processing module 1824A-D on the right side of the dashed dividing line, for example, on a wafer fab floor. Each flow path 1822A-D is configured to flow the mixture of precursor vapor and inert gas and includes delivery conduits and other flow components to control and guide the flow of the mixture to the corresponding processing module 1824A-D. Each flow path is also configured to maintain the mixture at a temperature between approximately 100°C and 150°C, which may include heating elements in the delivery conduit with a heated flow path and / or insulation around the delivery conduit. Each flow path also has a high-temperature mass flow controller located at or near the corresponding processing module 1824A-D, which 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 can be varied, resulting in 2, 3, 4, 5, 6, 7, 8, or 10 processing modules and corresponding flow paths.

[0255] The foregoing describes embodiments of the invention implemented in single-chamber or multi-chamber semiconductor processing tools. The apparatus and processes described herein can be used in conjunction with photolithography patterning tools or processes, for example, for fabricating or manufacturing semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, although not necessarily, these tools / processes will be used together or operated in a common manufacturing facility. Photolithography patterning of films typically includes some or all of the following steps, each step enabling multiple feasible tools: (1) applying a photoresist to a workpiece, i.e., a substrate, using a spin coater or spray coater; (2) curing the photoresist using a hot plate or oven or a UV curing tool; (3) exposing the photoresist to visible light or ultraviolet or X-rays using a tool such as a wafer stepper; (4) developing the photoresist to selectively remove the photoresist and thereby patterning it using a tool such as a wet cleaning station; (5) transferring the photoresist pattern onto the underlying film or workpiece using a dry or plasma-enhanced etching tool; and (6) removing the photoresist using a tool such as an RF or microwave plasma stripper.

Claims

1. A method comprising: A substrate is provided to the chamber, the substrate comprising features to be filled with molybdenum, the features having one or more openings; A conformal film of molybdenum is deposited in the feature; Non-conformal processing of the conformal film to improve the etching rate, wherein the processing is preferentially applied to the portion of the conformal film closer to the one or more openings relative to the portion of the conformal film farther away from the one or more openings; Non-conformal etching of the conformal film; and Molybdenum is deposited within the feature.

2. The method according to claim 1, wherein the feature is a word line feature of a 3D NAND structure.

3. The method of claim 2, wherein the word line feature has a first opening and a second opening, the first opening and the second opening being at opposite ends of the feature.

4. The method of claim 3, wherein the first opening leads to a first vertical structure of the 3D NAND structure and the second opening leads to a second vertical structure, and wherein fluid can enter the feature via the first vertical structure and the second vertical structure.

5. The method of claim 4, wherein the feature is further defined by a contraction formed by pillars of the 3D NAND structure.

6. The method of claim 1, wherein non-conformal processing of the conformal film to improve the etching rate comprises: oxidation or nitriding.

7. The method of claim 1, further comprising: processing the feature after non-conformal etching of the conformal film.

8. The method of claim 1, further comprising: after depositing molybdenum within the feature, nonconformally etching molybdenum, wherein the molybdenum is preferentially etched in the vicinity of the one or more openings.

9. The method of claim 1, wherein the conformal film of molybdenum deposited in the feature comprises: depositing a molybdenum-containing pad using a molybdenum precursor and ammonia.

10. The method of claim 9, wherein the conformal film for depositing molybdenum further comprises: depositing a conformal layer of molybdenum on the molybdenum-containing pad using a molybdenum precursor and hydrogen.

11. An apparatus comprising: A multi-station chamber, wherein each station includes: a substrate support configured to support a substrate; a nozzle configured to introduce gas into a volume above the substrate support; and a plasma generator configured to generate plasma between the substrate support and the nozzle; and A controller having instructions for: depositing a conformal film of molybdenum in a feature; non-conformally processing the conformal film to increase the etching rate, wherein the processing preferentially acts on portions of the conformal film closer to the one or more openings relative to portions of the conformal film farther from the one or more openings; non-conformally etching the conformal film; and depositing molybdenum within the feature.

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