Low-resistance molybdenum deposition for logic source / drain contacts.

Abstract

An efficient method is provided for filling conformal layer lined features in semiconductor substrates that utilizes a metal precursor to selectively deposit metal at the bottom of the feature and etch the conformal layer lining from the feature sidewalls.

Description

[Technical field]

[0001] Incorporated by reference: A PCT application is being filed contemporaneously herewith as a part of this application, and each application identified in that contemporaneously filed PCT application to which this application claims benefit or priority is hereby incorporated by reference in its entirety for all purposes. [Background technology]

[0002] The deposition of conductive materials is an essential part of many semiconductor fabrication 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. In one example of deposition, a tungsten (W) layer can be deposited on a titanium nitride (TiN) barrier layer by a chemical vapor deposition (CVD) process using tungsten (VI) fluoride (WF6) to form a TiN / W bilayer. However, the continuing reduction in feature size and film thickness brings various challenges to the TiN / W film stack. Challenges include high resistivity for thinner tungsten films and degradation of TiN barrier properties.

[0003] The background description provided herein is intended to provide a general overview of the contents of the present disclosure. Work by the currently named inventors within the scope of what is described in this Background section, as well as aspects of the description that may not otherwise be regarded as prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure. Summary of the Invention

[0004] A method is provided for filling a feature with molybdenum. The feature can include a conductive bottom and dielectric sidewalls and can be lined with a conformal liner layer. In some embodiments, the feature including the conformal liner layer is exposed to a molybdenum precursor with dual etching and deposition capabilities. Molybdenum is selectively deposited on the bottom of the feature and the conformal layer is etched from the sidewalls of the feature. In some embodiments, the conformal liner layer is a titanium nitride (TiN) layer. It can be selectively removed without disturbing an underlying layer, such as a titanium disilicide (TiSi2) layer. As a result, an oxygen-free, low-resistance molybdenum contact to the conductive bottom is formed.

[0005] Thus, in a first aspect, the disclosure encompasses a method for filling a feature. In some embodiments, the method includes providing a substrate with a feature having a feature bottom and feature sidewalls in a deposition chamber, the feature having a conformal liner layer. The conformal liner layer lines the feature such that the feature has a lined feature bottom surface and a lined feature sidewall surface. The method further includes selectively depositing a metal film on the lined feature bottom surface using a metal precursor and a reducing agent to form a metal film base, preferentially etching the conformal liner layer from the feature sidewalls upon etching the metal film base with the metal precursor, and depositing metal in the feature on the metal film base using the metal precursor.

[0006] In some embodiments, the reducing agent is hydrogen, hydrazine, ammonia, silane, disilane, diborane, or a combination thereof.

[0007] In some embodiments, the conformal liner layer is titanium nitride, titanium silicide nitride, tungsten carbon nitride, or a combination thereof.

[0008] In some embodiments, the metal precursor is a molybdenum halide, a molybdenum oxyhalide, or a combination thereof.

[0009] In some embodiments, forming the metal film base and etching the conformal liner layer from the sidewalls are performed sequentially.

[0010] In some embodiments, forming the metal film base and etching the conformal liner layer from the sidewalls occurs simultaneously.

[0011] In some embodiments, the molybdenum halide is molybdenum dichloride, molybdenum trichloride, molybdenum tetrachloride, molybdenum pentachloride, molybdenum hexachloride, or molybdenum fluoride.

[0012] In some embodiments, the molybdenum oxyhalide is molybdenum dioxide dichloride, molybdenum dioxide tetrachloride, molybdenum dioxide tetrafluoride, or molybdenum dioxide dibromide.

[0013] In some embodiments, the temperature of the substrate during deposition is between about 350°C and about 550°C.

[0014] In some embodiments, the pressure in the deposition chamber is between about 10 Torr and about 50 Torr.

[0015] In some embodiments, the depositing includes filling the feature with a metal.

[0016] In some embodiments, the substrate includes a top surface, where the top surface is coated with titanium disilicide.

[0017] In some embodiments, the method also includes pretreating and cleaning the conformal liner layer prior to deposition of the metal film.

[0018] In some embodiments, preferentially etching is etching the conformal liner layer from the feature sidewalls without etching the metal film base.

[0019] In a second aspect, the present disclosure includes a method for filling a feature. In some embodiments, the method includes: providing a substrate with a feature having a feature bottom and a feature sidewall in a deposition chamber, the feature having a conformal liner layer with a backed feature bottom surface and a backed feature sidewall surface; selectively depositing a molybdenum film on the backed feature bottom surface using a molybdenum precursor and a reducing agent to form a molybdenum film base; preferentially etching the conformal liner layer with a molybdenum precursor in etching the molybdenum film base and removing the backed feature sidewall surface; and depositing molybdenum in the feature on the molybdenum film base using a molybdenum precursor.

[0020] In some embodiments, preferentially etching is etching the conformal liner layer from the feature sidewalls without etching the metal film base.

[0021] In some embodiments, the molybdenum precursor is a molybdenum halide or a molybdenum oxyhalide.

[0022] In some embodiments, the molybdenum oxyhalide is molybdenum dioxide dichloride, molybdenum dioxide tetrachloride, molybdenum dioxide tetrafluoride, or molybdenum dioxide dibromide.

[0023] In some embodiments, the molybdenum halide is molybdenum dichloride, molybdenum trichloride, molybdenum tetrachloride, molybdenum pentachloride, molybdenum hexachloride, or molybdenum fluoride.

[0024] In some embodiments, the molybdenum halide is molybdenum pentachloride.

[0025] In a third aspect, the present disclosure encompasses a method for filling a feature. In some embodiments, the method includes: providing a substrate with a feature having a feature bottom and a feature sidewall in a deposition chamber, the feature having a conformal liner layer with a backed feature bottom surface and a backed feature sidewall surface; selectively depositing a molybdenum film on the backed feature bottom surface using a first molybdenum precursor and a reducing agent to form a molybdenum film base; preferentially etching the conformal liner layer using a second molybdenum precursor in etching the molybdenum film base and removing the backed feature sidewall surface; and depositing molybdenum in the feature on the molybdenum film base using the first molybdenum precursor.

[0026] In some embodiments, preferentially etching is etching the conformal liner layer from the feature sidewalls without etching the metal film base.

[0027] In a fourth aspect, the present disclosure encompasses an apparatus for filling a feature on a substrate. In some embodiments, the apparatus includes at least one deposition chamber having a pedestal for holding a substrate having a feature with a feature bottom and feature sidewalls, the feature having a conformal liner layer on the backed feature bottom surface and the backed feature sidewall surface, at least one inlet port for delivering a gas phase metal precursor to the deposition chamber, and a controller for controlling operation in the apparatus, the controller including machine readable instructions for depositing a molybdenum film on the backed feature bottom surface using a molybdenum precursor and a reducing agent, preferentially etching the conformal liner layer using a molybdenum precursor and removing the backed feature sidewall surface in etching the backed feature bottom surface feature, and depositing molybdenum in the feature using a molybdenum precursor after (b).

[0028] These and other aspects are further described below with reference to the drawings. [Brief description of the drawings]

[0029] [Figure 1A] FIG. 1A is a schematic example of a material stack including molybdenum (Mo), according to certain disclosed embodiments. [Figure 1B] FIG. 1B is a schematic example of a material stack including molybdenum (Mo), according to certain disclosed embodiments.

[0030] [Figure 2A] FIG. 2A is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2B] FIG. 2B is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2C] FIG. 2C is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2D] FIG. 2D is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2E] FIG. 2E is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2F] FIG. 2F is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2G] FIG. 2G is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2H] FIG. 2H is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2I] FIG. 2I is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2J] FIG. 2J is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2K]FIG. 2K is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments. [Figure 2L] FIG. 2L is a schematic example of various structures onto which molybdenum may be deposited, according to certain disclosed embodiments.

[0031] [Diagram 3] FIG. 3 is a flow diagram illustrating certain operations for filling a feature with metal in accordance with certain disclosed embodiments.

[0032] [Figure 4A] FIG. 4A is a schematic diagram illustrating a cross-sectional view of a feature during a filling process in accordance with certain disclosed embodiments. [Figure 4B] FIG. 4B is a schematic diagram illustrating a cross-sectional view of a feature during a filling process in accordance with certain disclosed embodiments. [Figure 4C] FIG. 4C is a schematic diagram illustrating a cross-sectional view of a feature during a filling process in accordance with certain disclosed embodiments. [Figure 4D] FIG. 4D is a schematic diagram illustrating a cross-sectional view of a feature during a filling process in accordance with certain disclosed embodiments.

[0033] [Figure 5A] FIG. 5A is a schematic diagram illustrating a cross-sectional view of a feature during a filling process in accordance with certain disclosed embodiments. [Figure 5B] FIG. 5B is a schematic diagram illustrating a cross-sectional view of a feature during a filling process in accordance with certain disclosed embodiments. [Figure 5C] FIG. 5C is a schematic diagram illustrating a cross-sectional view of a feature during a filling process in accordance with certain disclosed embodiments.

[0034] [Figure 6] FIG. 6 illustrates an example of an apparatus that may be used to implement the methods described herein, in accordance with certain disclosed embodiments.

[0035] [Figure 7A] FIG. 7A illustrates an example of an apparatus that may be used to implement the methods described herein, in accordance with certain disclosed embodiments. [Figure 7B] FIG. 7B illustrates an example of an apparatus that may be used to implement the methods described herein, in accordance with certain disclosed embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments. It will be understood that while the disclosed embodiments will be described in conjunction with specific embodiments, they are not intended to limit the disclosed embodiments.

[0037] definition As used herein, the term "about" is understood to allow for slight increases and / or decreases beyond the recited value, changes that do not significantly affect the desired function of the parameter beyond the recited value. In some cases, "about" encompasses + / - 10% of the recited value. As used herein, the term modifies a recited value, a range of values, or one or more end points of a range.

[0038] As used herein, the terms "top," "bottom," "upper," "lower," "above," and "below" are used to provide relative relationships between structures. Use of these terms does not indicate or require that a particular structure must be located in a particular location within the apparatus.

[0039] As used herein, the phrase "at least one of A, B, and C" should be interpreted in the sense of a logical (A or B or C) using a non-exclusive logical OR, and not in the sense of "at least one of A, at least one of B, and at least one of C."

[0040] In this disclosure, the terms "semiconductor wafer," "wafer," "substrate," "wafer substrate," and "partially fabricated integrated circuit" are used interchangeably. Those skilled in the art will understand that the term "partially fabricated integrated circuit" can refer to a silicon wafer at any of the many stages of integrated circuit fabrication. Wafers or substrates used in the semiconductor device industry typically have diameters of 200 mm, or 300 mm, or 450 mm. The following detailed description assumes that the present disclosure is implemented on a wafer. However, the disclosure is not so limited. Workpieces may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that may utilize the present disclosure include various articles such as printed circuit boards. The term "semiconductor substrate" or "substrate," as used herein, refers to a substrate at any stage of semiconductor device fabrication that includes semiconductor material anywhere within its structure. It is understood that the semiconductor material in a semiconductor substrate need not be exposed. A semiconductor wafer having multiple layers of other materials (e.g., dielectrics) covering the semiconductor material is an example of a semiconductor substrate. The following detailed description assumes that the disclosed embodiments are implemented on a semiconductor wafer, such as a 200 mm, 300 mm, or 450 mm semiconductor wafer. However, the disclosed embodiments are not so limited. Workpieces may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that may utilize the disclosed embodiments include various articles such as printed circuit boards.

[0041] It is understood that throughout this specification, the identifiers "first" and "second" are used only to aid in distinguishing various components and / or steps of the disclosed subject matter. The identifiers "first" and "second" are not intended to imply a particular order, quantity, priority, or importance to the components and / or steps modified by these terms.

[0042] The substrate may be a silicon wafer, e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, including a wafer having one or more layers of materials, such as dielectric, conductive, or semiconductor materials, deposited thereon. In various embodiments, the substrate is patterned. The patterned substrate may have "features," such as pillars, poles, trenches, via holes, or contact holes, which may be characterized by one or more of narrow and / or reentrant openings, constrictions within the features, and high aspect ratios. The features may be formed in one or more of the layers mentioned above. One example of a feature is a pillar or pole in a semiconductor substrate or a layer on the substrate. Another example is a trench in the substrate or layer.

[0043] In some embodiments, the features may have an aspect ratio of at least about 1:1, at least about 2:1, at least about 4:1, at least about 6:1, at least about 10:1, or more. The features may also have a dimension near the opening, e.g., an opening diameter or line width, of about 10 nm to 500 nm, e.g., about 25 nm to about 300 nm. The disclosed methods may be performed on substrates with features having openings of less than about 150 nm. Vias, trenches, or other recessed features may be referred to as unfilled or negative features. According to various embodiments, the feature profile may narrow gradually and / or include an overhang at the feature opening. A re-entrant profile is a profile that narrows from the bottom, closed end, or interior of the feature to the feature opening. A re-entrant profile may be produced by overhangs due to asymmetric etch kinetics during patterning and / or non-conformal film step coverage in a previous film deposition, such as deposition of a diffusion barrier. In various examples, a feature may have a smaller width at the opening at the top of the feature than the width at the base of the feature.

[0044] Provided herein is a method for filling features with molybdenum (Mo) that can be used for logic applications. Mo offers several advantages over other metals such as cobalt (Co), ruthenium (Ru), and tungsten (W): (i) barrier-less and liner-less Mo film deposition is more feasible on oxides and nitrides compared to Co, Ru, and W, (ii) Mo has better resistivity scaling than W, and (iii) Mo is relatively easy to integrate into current W schemes compared to Co and Ru.

[0045] As used herein, the underlayer silicide (e.g., titanium silicide or TiSi xA method for depositing Mo on source / drain (S / D) features is provided that prevents damage to the Mo layer. Although the following description focuses on Mo deposition for source / drain contacts, aspects of the method can also be used for other metallization schemes in logic and / or memory applications.

[0046] 1A and 1B are schematic examples of material stacks including Mo according to various embodiments. FIG. 1A and 1B show the order of materials in a particular stack example, which can be used in any suitable architecture and application, as further described below with respect to FIG. 2A-2L. FIG. 1A shows a first material stack 111 featuring a substrate 102 and a Mo layer 108 deposited thereon. The substrate 102 can be a silicon or other semiconductor wafer, e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, including a wafer having one or more layers of material, such as a dielectric material, a conductive material, or a semiconductor material, deposited thereon. In some embodiments, the substrate 102 can be or include silicon (Si) or silicon germanium (SiGe). The method can also be applied to form metallization stack structures on other substrates, such as glass, plastic, and the like.

[0047] The stack 111 has a dielectric layer 104 on a substrate 102. The dielectric layer 104 may be deposited directly on a semiconductor surface (e.g., a Si or SiGe surface) of the substrate 102, or there may be any number of intervening layers. For example, the substrate 102 may include any number of layers deposited in various arrangements on the semiconductor surface.

[0048] Examples of dielectric layers include doped and undoped silicon oxide, silicon nitride, and aluminum oxide layers, with specific examples including doped or undoped layers of SiO2 and Al2O3. The stack 111 has a layer 106 disposed between the Mo layer 108 and the dielectric layer 104. The layer 106 may be, for example, a diffusion barrier and / or adhesion layer. A diffusion barrier is a layer that prevents diffusion of species between layers. An adhesion layer is a layer that promotes adhesion of a layer to an underlying layer. Examples of diffusion barrier and adhesion layers include titanium nitride (TiN), titanium / titanium nitride (Ti / TiN), tungsten (W), tungsten nitride (WN), and tungsten carbon nitride (WCN). The Mo layer 108 is the main conductor of the structure. In some embodiments, the Mo layer 108 can include multiple bulk layers deposited at different conditions. The Mo layer 108 may or may not include a Mo nucleation layer. Additionally, in some embodiments, the Mo layer 108 may be deposited on a growth-initiating layer that includes another material, such as tungsten (W) or a W-containing growth-initiating layer.

[0049] 1B shows another example of a material stack 121. In this example, stack 121 includes substrate 102, dielectric layer 104, and Mo layer 108 deposited directly on dielectric layer 104 without an intervening diffusion barrier or adhesion layer. Mo layer 108 is as described with respect to FIG. 1A. By using Mo (which has a lower electron mean free path than W) as the main conductor, a lower resistivity thin film can be obtained.

[0050] In some embodiments, the stack (not shown) can include a substrate, a nitride, silicide, or metal layer, and a Mo layer deposited on the nitride, silicide, or metal layer. In these embodiments, there is no dielectric layer between the Mo layer and the nitride, silicide, or metal layer. Examples include Mo on a metal nitride layer (e.g., TiN, WN, WCN, or MoN), a metal silicide layer (e.g., TiSi x , or tungsten silicide (WSi x) or on a metal layer (e.g., W). In yet some other embodiments of the stack (not shown), the stack may include a substrate and a Mo layer deposited directly on the substrate, including on a semiconducting surface, a dielectric surface, or a conductive surface. Figures 1A and 1B show examples of material ordering in certain stacks, which may be used in any suitable architecture and application, as further described below with respect to Figures 2A-2L.

[0051] The method described herein is carried out on a substrate that may be housed in a chamber. The substrate may be a silicon or other semiconductor wafer, including a wafer having one or more layers of materials, such as dielectric, conductive, or semiconductor materials, deposited thereon. The method is not limited to semiconductor substrates and may be carried out to fill any feature with molybdenum.

[0052] The substrate may have features, such as vias or contact holes, which may be characterized by one or more of narrow and / or reentrant openings, constrictions within the features, and high aspect ratios. The features may be formed in one or more of the stacks or layers within the stacks described above. For example, the features may be formed at least partially in a dielectric layer. In some embodiments, the features may have an aspect ratio of at least about 2:1, at least about 4:1, at least about 6:1, at least about 10:1, at least about 25:1, or more. One example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate.

[0053] FIG. 2A illustrates a schematic example of a dynamic random access memory (DRAM) architecture including a Mo buried word line (bWL) 208 in a silicon substrate 202. The Mo bWL is formed in a trench etched into the silicon substrate 202. The trench is lined by a conformal barrier layer 206 and an insulating layer 204. The conformal barrier 206 is disposed between the insulating layer 204 and the silicon substrate 202. In this example, the insulating layer 204 may be a gate oxide layer formed from a high-k dielectric material such as a silicon oxide or silicon nitride material. In some embodiments disclosed herein, the conformal barrier layer 206 is a TiN or tungsten-containing layer. In embodiments where TiN is used as the conformal barrier layer, a conformal tungsten-containing growth-initiating layer (not shown) may be present between the conformal barrier layer 206 and the Mo bWL 208. Alternatively, the Mo bWL 208 may be deposited directly on the TiN or other diffusion barrier. In some embodiments, one or both of the layers 204 and 206 are absent.

[0054] 2A is an example of an architecture that includes a Mo fill layer. During bWL fabrication, Mo is deposited into features that may be defined by etched recesses in a silicon substrate 202 that is conformally lined with layers 206 and 204, if present.

[0055] 2B-2H are additional schematic examples of various structures on which Mo may be deposited, according to disclosed embodiments. FIG. 2B shows an example of a cross-sectional view of a vertical feature 201 to be filled with Mo. The feature may include a feature hole 205 in a substrate 202. The feature hole 205 may have a conformal liner layer 203 lining the sidewalls or interior of the feature hole 205, or may form an interior surface. The hole 205 or other feature may have a dimension near the opening, e.g., an opening diameter or line width, of about 10 nm to 500 nm, e.g., about 25 nm to about 300 nm. The feature hole 205 may be referred to as an unfilled feature or simply a feature. The feature 201, and any feature, may be characterized in part by an axis 218 that extends the length of the feature, with vertically oriented features having a vertical axis and horizontally oriented features having a horizontal axis.

[0056] In some embodiments, the features are wordline features in a 3D NAND structure. For example, the substrate can include a wordline structure having any number (e.g., 50-150) of wordlines with vertical channels at least 200 Å deep. Examples of wordline 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 can have an underlayer, such as a barrier layer or an adhesion layer. Non-limiting examples of underlayers include dielectric layers and conductive layers, such as silicon oxide, silicon nitride, silicon carbide, metal oxides, metal nitrides, metal carbides, and metal layers.

[0057] FIG. 2C shows an example of a feature 201 with a reentrant profile. A reentrant profile is a profile that narrows from the bottom, closed end, or interior of the feature to the feature opening. According to various embodiments, the profile may gradually narrow and / or include an overhang at the feature opening. FIG. 2C shows an example of the latter, where a conformal liner layer 213 lines the sidewalls and bottom of the feature hole 105. The conformal liner layer 213 can be a diffusion barrier layer, an adhesion layer, a nucleation layer, a combination thereof, or any other applicable material. Non-limiting examples of liner layers can include dielectric layers and conductive layers. Examples of dielectric materials include oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3), nitrides such as silicon nitride (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 certain embodiments, the liner layer may be one or more of titanium, titanium nitride, tungsten nitride, titanium aluminide, tungsten, and molybdenum.

[0058] The conformal liner layer 213 forms an overhang 215 such that the conformal liner layer 213 is thicker near the opening of the feature 201 than inside the feature 201 .

[0059] In some implementations, features can be filled that have one or more constrictions within the feature. FIG. 2D shows example diagrams of various filled features with constrictions. Examples (a), (b), and (c) of FIG. 2D each include a constriction 209 at a midpoint within the feature. The constriction 209 can be, for example, about 15 nm to 20 nm in width. The constriction can cause pinch-off during deposition molybdenum in the feature using conventional techniques, where the deposited metal blocks further deposition past the constriction before that portion of the feature is filled, resulting in a void in the feature. Example (b) further includes a liner / barrier overhang 215 at the feature opening. Such an overhang can also be a potential pinch-off point. Example (c) includes a constriction 212 that is further away from the field region than the overhang 215 of example (b).

[0060] Horizontal features such as 3-D memory structures can also be filled. FIG. 2E shows an example of a horizontal feature 250 that includes a constriction 251. For example, the horizontal feature 250 may be a word line in a 3D NAND (also called vertical NAND or VNAND) structure. In some implementations, the constriction may result from the presence of pillars in the 3D NAND or other structures. FIG. 2F presents a cross-sectional side view of a 3-D NAND structure 210 (formed on a silicon substrate 202) with a VNAND stack (left side 225 and right side 226), a central vertical structure 230, and multiple stacked horizontal features 220 with openings 222 on both side walls 240 of the central vertical structure 230. It should be noted that while FIG. 2F shows two “stacks” of the presented 3-D NAND structure 210, which together form a “trench-like” central vertical structure 230, in certain embodiments, three or more “stacks” may be arranged in sequence and extend spatially parallel to one another, with the gap between each adjacent pair of “stacks” forming the central vertical structure 230 as explicitly shown in FIG. 2F. In this embodiment, the horizontal feature 220 is a 3-D memory word line feature that is fluidically accessible from the central vertical structure 230 through the opening 222. As shown more clearly in FIG. 2G described below, a constriction may be formed in the horizontal feature 220 due to the presence of the pillars 255. Although not explicitly shown in the figure, the horizontal features 220 present in both 3-D NAND stacks 225 and 226 shown in FIG. 2F (i.e., the left 3-D NAND stack 225 and the right 3-D NAND stack 226) are also accessible from the other sides of the stacks (left and right ends, respectively) through similar vertical structures formed by additional 3-D NAND stacks (to the left and right ends, but not shown). Each 3-D NAND stack 225, 226 includes a stack of word line features that are fluidly accessible from both sides of the 3-D NAND stack through a central vertical structure 230. In the particular example shown diagrammatically in FIG. 2F, each 3-D NAND stack includes six pairs of stacked word lines.However, a 3-D NAND memory layout can include any number of vertically stacked pairs of word lines.

[0061] Word line features in a 3-D NAND stack can be formed by depositing an alternating stack of silicon oxide and silicon nitride layers and then selectively removing the nitride layers to leave a stack of oxide layers with gaps between them. These gaps are the word line features. Any number of word lines can be stacked vertically in such a 3-D NAND structure, so long as techniques are available to form the word lines, and so long as there are techniques available to successfully achieve (substantially) void-free filling of the vertical features. Thus, for example, a VNAND stack can include 2-512 horizontal word line features, 2-256 horizontal word line features, or 8-128 horizontal word line features, or 16-64 horizontal word line features, etc. (the recited ranges are understood to include the stated endpoints).

[0062] FIG. 2G presents a cross-sectional top view of the same 3-D NAND structure 210 shown in the side view of FIG. 2F, with the cross section taken through a horizontal section 260 as indicated by the horizontal dashed line in FIG. 2F. The cross section in FIG. 2G shows several rows of pillars 255 shown in FIG. 2F as extending vertically from the base of the semiconductor substrate 202 to the top of the 3-D NAND stack 210. In some embodiments, these pillars 255 are formed from polysilicon material and are structurally and functionally important to the 3-D NAND structure 210. In some embodiments, such polysilicon pillars can function as gate electrodes for stacked memory cells formed within the pillars. The top view in FIG. 2G shows that the pillars 255 form a constriction at the opening 222 to the word line feature 220. Fluidic accessibility of the word line feature 220 from the central vertical structure 230 through the opening 222 (indicated by the arrow in FIG. 2G) is inhibited by the pillars 255. In some embodiments, the size of the horizontal gap between adjacent polysilicon pillars is about 1-20 nm. This reduced fluid accessibility increases the difficulty of uniformly filling the wordline features 120 with material. The structure of the wordline features 220 and the challenge of uniformly filling them with molybdenum material due to the presence of pillars 255 are further illustrated in Figures 2H, 2I, and 2J.

[0063] FIG. 2H shows a vertical cross-section of a 3-D NAND structure similar to that shown in FIG. 2F, but now focusing on a single pair of wordline features 220, and additionally illustrates a filling process that results in the formation of a void 275 within the filled wordline feature 220. FIG. 2I also illustrates the void 275 generally, but in this view through a horizontal cross-section of the pillar 255, similar to the horizontal cross-section shown in FIG. 2G. FIG. 2J shows the buildup of molybdenum material around the constriction-forming pillar 255, which causes a pinch-off of the opening 222, such that additional molybdenum material cannot be deposited in the region of the void 275. As is evident from Figures 2H and 2I, void-free molybdenum fill relies on a sufficient amount of deposition precursor migrating through vertical structure 230, through opening 222, past narrowing pillar 255, and to the furthest extent of wordline feature 220 before molybdenum accumulates and deposits around pillar 255, causing pinch-off of opening 222 and preventing further precursor migration into wordline feature 220. Similarly, Figure 2J shows a single wordline feature 220 in cross-sectional view from above, illustrating how the generally conformal deposition of molybdenum material begins to pinch off the interior of wordline feature 220 due to the fact that the significant width of pillar 255 acts to partially block and / or narrow and / or narrow what would otherwise be an open path through wordline feature 220. (Note that the example in FIG. 2J can be understood as a 2-D rendering of the 3-D features of the pillar constriction structure shown in FIG. 2I, and thus shows the constriction as seen in plan view rather than in cross section.)

[0064] Three-dimensional structures may require longer and / or more focused exposure to the precursor to ensure that the innermost and bottommost areas are filled. Three-dimensional structures can be particularly challenging when using molybdenum halide and / or molybdenum oxyhalide precursors, as they tend to etch with longer and more focused exposures that allow for more etching as part of the structure.

[0065] 2K and 2L show examples of asymmetric trench structure DRAM bWL. Some filling processes for DRAM bWL trenches can distort the trench such that the final trench width and resistance Rs are significantly non-uniform. FIG. 2K shows a narrow asymmetric trench structure DRAM bWL unfilled 261 and filled 265 exhibiting line bending after filling. As shown, a plurality of features 283 are illustrated on a substrate. These features 283 are spaced apart, and in some embodiments, adjacent features have a pitch of about 20 nm to about 60 nm, or about 20 nm to 40 nm. The pitch is defined as the distance between the central axis of one feature and the central axis of an adjacent feature. The unfilled feature 283 can be generally V-shaped as shown in feature 283, with sloping sidewalls where the width of the feature narrows from the top of the feature to the bottom of the feature. The feature extends from the feature bottom 273b to the feature top 273a. After several filling operations, line bending may be observed within the feature 283, as shown on the substrate 265. Without being bound to a particular theory, it is believed that cohesive forces between the opposing surfaces of the trench pull the sides of the trench together as illustrated by the arrows 267. This phenomenon is illustrated in FIG. 2L and may be characterized as "zipping up" the feature. As the feature 283 fills, more force is exerted from the central axis 299 of the feature 283, resulting in line bending. For example, molybdenum may be deposited on the sidewalls of the feature 283. The molybdenum 284a and 284b deposited on the sidewalls of the feature 283 interact in close proximity when the molybdenum-molybdenum bond radius r is small, which creates cohesive interatomic forces between the smooth growth surfaces of the tungsten, pulling the sidewalls together and resulting in line bending. Methods of filling features to reduce line bending are described below.

[0066] A method for filling features with Mo is provided below. The methods described herein include deposition, etching, and cleaning operations that can be used to fill substrate features such as those described above. Further examples of features are described below with respect to Figures 4A-4D and 5A-5C.

[0067] Examples of feature filling for horizontally and vertically oriented features are described below. Note that, at least in most cases, these examples are applicable to both horizontally or vertically oriented features. Horizontally oriented features generally refer to features oriented such that the feature axis is parallel to the plane of the substrate surface. Vertically oriented features generally refer to features oriented such that the feature axis is perpendicular to the plane of the substrate surface.

[0068] The deposition of molybdenum as described herein involves reacting a Mo-containing precursor, also referred to as a Mo precursor. In some embodiments, the Mo precursor is a molybdenum chloride precursor or MoCl x Molybdenum chloride (MoCl), also known as the precursor x ) compound. The molybdenum chloride precursor has the formula MoCl x where x is 2, 3, 4, 5, or 6, including molybdenum dichloride (MoCl2), molybdenum trichloride (MoCl3), molybdenum tetrachloride (MoCl4), molybdenum pentachloride (MoCl5), and molybdenum hexachloride (MoCl6). In some embodiments, MoCl5 or MoCl6 are used. The description is primarily focused on MoCl x Although the precursor is mentioned, in other embodiments, other molybdenum halide precursors may be used. The molybdenum halide precursors have the formula MoX z 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, non-fluorine-containing MoX zThe precursors are used to prevent etching or incorporation of fluorine. In some embodiments, non-bromine-containing and / or non-iodine-containing MoX z The precursors are used to prevent etching or incorporation of bromine or iodine.

[0069] In some embodiments, the features may be filled using a molybdenum oxyhalide precursor having the formula MoO y X z where X is a halogen (fluorine (F), chlorine (Cl), bromine (Br), or iodine (I)) and y and z are MoO y X z is a number greater than 0 such that a stable compound is formed. Examples of molybdenum oxyhalides include molybdenum dioxide dichloride (MoO2Cl2), molybdenum oxide tetrachloride (MoOCl4), molybdenum oxide tetrafluoride (MoOF4), molybdenum dioxide dibromide (MoO2Br2), and the molybdenum oxyiodides MoO2I, MoO2F2, MoO2I2, MoOBr4, MoOI4, and Mo4O 11 I. Features include MoCl x Precursor, MoO y X z The Mo-filled precursors may be used, for example, in a SiO2-containing ...

[0070] In some embodiments, selectively depositing molybdenum on the metal-containing bottom comprises exposing the feature to a molybdenum oxyhalide. In some embodiments, the treatment inhibits the growth of molybdenum on oxide or nitride sidewalls. In some embodiments, the treatment is performed without depositing molybdenum in the feature. In some embodiments, the treatment further comprises exposing the feature to a co-reactant capable of reducing the molybdenum halide to form molybdenum.

[0071] In certain embodiments, the precursor is a molybdenum halide (MoX z) and the molybdenum oxyhalide precursor (MoO y X z ) combination.

[0072] To deposit Mo into the features, the Mo precursor can be reacted with a co-reactant, examples of which include hydrogen (H2), silane (SiH4), diborane (B2H6), germane (GeH4), ammonia (NH3), and hydrazine (N2H4).

[0073] In some embodiments, the deposition of Mo can use a plasma-based process. Gas can be fed into a remote or in-situ plasma generator to generate plasma species. Examples of gases that can be used to generate plasma can be hydrogen-containing gases such as H2, or nitrogen-containing gases such as N2. The plasma species can be inert or can react with the Mo precursor to form a film.

[0074] The features can be filled with Mo by atomic layer deposition (ALD) or chemical vapor deposition (CVD). Thermal ALD or plasma enhanced ALD (PEALD) may be used. Similarly, thermal CVD or plasma enhanced CVD (PECVD) may be used.

[0075] ALD is a surface-mediated deposition technique in which doses of precursors and reactants are introduced sequentially into a deposition chamber. Mo can be deposited using one or more cycles of sequential doses of Mo precursor and reactant. For example, in the deposition of the initial Mo layer, MoCl5 can be used as the precursor and H2 as the reducing agent. The reducing agent is also called a co-reagent. The pulse sequence is generally: 1) introduction of the reducing agent, 2) optional Ar purge, 3) introduction of the molybdenum-containing precursor, and 4) optional Ar purge.

[0076] For example, doses of MoCl5 and H2 can be introduced sequentially into the deposition chamber with a purge gas such as argon flowing between them. For ALD, the temperature of the substrate and the pressure of the chamber can be controlled. For example, the substrate can be heated to 500°C to 800°C, e.g., 650°C to 750°C. In some embodiments, the chamber can be pressurized to at least 10 Torr, e.g., at least 30 Torr. In some embodiments, the temperature and / or pressure can be used to control the reaction rate. In some embodiments, the temperature and / or pressure can be used to control the selectivity.

[0077] In some embodiments, Mo filling may involve CVD. In a CVD process, Mo precursors and reactants are in the gas phase together in a deposition chamber. Generally, CVD processes fill features faster than ALD processes. In one example, the precursor may be a molybdenum chloride, such as MoCl5, which is flowed into the chamber along with a reactant, such as H2. In this example, the wafer is exposed to the precursor and reactant simultaneously, which react to fill the feature with Mo.

[0078] In yet some other embodiments, the features can be filled using a pulsed CVD process, in which a reactant is continuously flowed into the chamber while a pulse of a precursor is flowed into the chamber. For example, H2 gas can be flowed into the chamber and H2 gas can be continuously flowed into the chamber while MoCl5 is intermittently flowed into the chamber. The temperature of the substrate and the pressure in the chamber can be controlled during the CVD operation.

[0079] Using the methods described herein, Mo can be selectively deposited in a feature. In selective deposition, Mo fill can be easily deposited on a first material compared to a second material, e.g., Mo deposition and growth can be easier on a metallic material compared to Mo deposition and growth on a dielectric material. For example, a feature can have a SiO2 sidewall surface and a TiN plug at a bottom portion of the feature. In selective deposition, Mo may be deposited in the feature and grow on the TiN plug but not (or grow to a lesser extent) on the SiO2 sidewall surface. In this example, by growing Mo from the bottom of the feature on the TiN plug but not on the sidewall surface, the feature avoids the line bending effect described above in FIG. 2L.

[0080] Process conditions such as precursor gas, reducing agent, substrate temperature, process pressure, and exposure time may affect the selectivity of the deposited Mo film. Different precursor gases may have different process windows in which Mo films can be selectively deposited. For example, MoCl5 has higher selectivity than MoO2Cl2, i.e., under the same temperature and pressure conditions, the precursor gas of MoCl5 deposits Mo only on conductive surfaces and not on dielectric surfaces, while the precursor gas of MoO2Cl2 can deposit Mo on both conductive and dielectric surfaces. Generally, MoCl5 gas has a wide process window, i.e., a wide temperature and pressure range, in which the precursor gas retains its selectivity. For example, MoCl5 can be selectively deposited on metal materials compared to dielectric materials when the process temperature is 300°C to 800°C. In some embodiments, the substrate temperature is 350°C to 550°C. Generally, a high process temperature and a high process pressure reduce the selectivity of the deposition gas. For example, at higher temperatures, a precursor gas such as MoCl5 may lose its selectivity and deposit a Mo film on both the metal and dielectric surfaces within the feature.

[0081] Examples of deposition of Mo films in features using MoCl5 precursor and different process controls are described below. In the first example, MoCl5 precursor is reacted with hydrogen (H2) reducing agent using the deposition method described above. The process temperature for selective deposition of Mo films can be 400°C to 800°C. At these temperatures, Mo films are selectively deposited on conductive metal or metal compound surfaces, such as TiN surfaces, in the feature compared to dielectric surfaces. The Mo film grows from where the conductive surface is located in the feature. If the conductive surface is a TiN plug at the bottom of the feature, the Mo film can be deposited and grown from the bottom of the feature. In the second example, Mo films can be deposited using MoCl5 precursor and H2 reactant, but at higher temperatures, i.e., above 800°C. This process window can have Mo films deposited on both dielectric and conductive surfaces in the feature.

[0082] MoCl x A precursor may be used for both deposition and etching operations. For example, in a certain process window, a MoCl5 precursor can grow a Mo film and simultaneously etch away a metal or metal compound film in a feature. If the rate of material removed is faster than the material deposited by the precursor, the process is considered an etching operation. The rate at which the precursor deposits material and etches material can be controlled by various process conditions, including the type of reactant used and the process temperature. In general, the lower the temperature, the higher the ratio of material etching removal to material deposition. At higher temperatures, the same precursor and reactant may be used as a deposition operation, i.e., the amount of material deposited is greater than the material removed. For example, if the process temperature is less than 400° C., a MoCl5 precursor and a H2 reactant may be used for the etching operation. If the process temperature is greater than 550° C., the same precursor of MoCl5 and H2 reactant may be used in the deposition operation. In some embodiments, the etching may be performed using MoCl5 or other MoCl without a co-reactant. xThis is accomplished by delivering a precursor, and as described further below, the net etch and / or deposition is controllably varied across the feature by introducing a precursor concentration gradient within the feature. In some embodiments, MoCl x The precursors are used for oxygen-free, fluorine-free deposition, however, other molybdenum halides and molybdenum oxyhalides may be used as described herein for etching and deposition.

[0083] The features may have surface oxides or contaminants. For example, the surface of an underlying TiN, WCN, WN, or W layer may be oxidized. When incorporated into a device, the oxidized surface may result in high resistivity. To remove such oxides and contaminants, a cleaning operation is used. In some embodiments, the cleaning operation may have the features immersed in a Mo precursor gas, typically a Mo halide. Similar to the etching operation described above, the precursor gas may be MoCl x In some embodiments, the soaking may be continuous. In some embodiments, the soaking may be pulsed, with MoCl x A purge gas such as argon (Ar) and argon (Ar) can be circulated. The precursor can be an oxygen-free Cl-containing Mo compound that can remove oxidation from the surface of the feature. MoCl x Examples of compounds are listed above. Cl-containing precursors can be used when traditional cleaning with thermal or plasma H2 does not work, such as when an oxidized surface is stable on the surface material. Cl-containing precursors are less likely to overetch the liner layer of the feature or attack the surface of the feature than F-containing compounds.

[0084] In some embodiments, the methods described herein involve the deposition of Mo onto a protective layer. For example, a nitride layer such as TiN can be used in a source / drain contact fashion to contact the underlying silicide (e.g., TiSi x) oxidation. In some embodiments, the methods described herein involve liner-free filling of the feature. For example, the feature may be provided with a conformal liner layer that acts as a protective layer against an underlying silicide or other layer. In some embodiments, the method involves removing a portion of the conformal liner layer while leaving a portion that protects the underlying layer. Removing the liner reduces the resistance of the contact or other filled feature.

[0085] FIG. 3 is a process flow diagram illustrating a method for filling a feature having a conformal liner layer with a Mo film. Although FIG. 3 describes the deposition of Mo, in other embodiments, the method may be used to deposit vanadium, niobium, tantalum, chromium, tungsten, iron, ruthenium, rhenium, rhodium, aluminum, iridium, nickel, zinc, or copper by using an appropriate metal precursor. In some embodiments, the feature has a conformal liner layer. Examples of conformal liner layers include metal oxides and metal nitrides. In some embodiments, the conformal liner layer is a protective nitride layer. The method 300 begins in operation 301 with providing a substrate including a feature having a conformal liner layer. The substrate may be provided in a semiconductor processing tool. In some embodiments, the conformal liner layer is a metal nitride layer, which may be a titanium nitride (TiN) layer. Deposition of a metal such as molybdenum on a TiN liner can cause seam voids and high contact resistance in the complete film stack. Liner-free contacts may have reduced resistance.

[0086] In some embodiments, the metal nitride layer may be a tungsten carbonitride (WCN) layer. Other nitrides and carbonitrides may also be used. In some embodiments, the layer may be an oxynitride, oxycarbide, or oxycarbonitride. The method is not limited to a particular protective layer and may be practiced with any protective layer. Furthermore, the method may be practiced to deposit metal in a feature without a protective layer in some embodiments.

[0087] In some embodiments, the features are formed in a dielectric material. Mo can be deposited in the features and form electrical contact with the underlayer. Examples of underlayers include metals, metal silicides, and semiconductors. Examples of metals include Co, Ru, copper (Cu), W, Mo, nickel (Ni), iridium (Ir), rhodium (Rh), tantalum (Ta), and Ti. Examples of metal silicides include TiSi x , Nickel silicide (NiSi x ), molybdenum disilicide (MoSi x ), cobalt silicide (CoSi x ), platinum silicide (PtSi x ), ruthenium silicide (RuSi x ), and nickel platinum silicide (NiPt y S x Examples of semiconductors include silicon (Si), silicon germanium (SiGe), and gallium arsenide (GaAs), with or without semiconducting dopants such as carbon (C), arsenic (As), boron (B), phosphorus (P), tin (Sn), and antimony (Sb).

[0088] A feature generally has a sidewall having a sidewall surface and a bottom having a bottom surface. The sidewall may be fabricated of one or more layers. The sidewall extends from the field to the bottom. The feature bottom may extend from a first sidewall in the feature to a second sidewall in the feature and may be fabricated of one or more layers. The sidewall surface is an exposed area on the sidewall that may change during wafer processing, for example, the sidewall surface may change from a first material to a second material after the second material is deposited on the sidewall. Similarly, the bottom surface is an exposed area on the bottom that may change during wafer processing. In some embodiments, the sidewall surface may be the same material as the bottom surface. For example, in some embodiments, the sidewall surface and the bottom surface are TiN. In some embodiments, the sidewall surface may be a different material than the material of the bottom surface.

[0089] In some embodiments, a conformal metal nitride layer forms the sidewall and bottom surfaces. For example, a TiN liner layer can line the unfilled features and form the sidewall and bottom surfaces.

[0090] In some embodiments, the feature surface provided in operation 301 is oxidized. Oxidation can be induced by exposing the surface of the feature to air or other oxidizing conditions. For example, a TiN liner surface oxidizes when exposed to air to form a titanium oxynitride layer (TiO x N y ). Other examples of oxidized surfaces include metal oxide nitrides (MN x O y ), silicon oxide (SiO x ), and silicon germanium oxide (SiGeO x (In the description herein, the subscripts x and y are used in formulas to indicate non-zero numbers. The absence of a subscript does not imply a particular ratio of elements in the compound.)

[0091] In some embodiments, oxidizing conditions occur during substrate processing or transfer operations, hi some embodiments, intentional oxidation is performed.

[0092] After providing a substrate having a metal nitride layer or other conformal liner layer and including a feature on which Mo is to be deposited, an optional clean may be performed in operation 302. The optional clean may be used to remove oxides on the surface of the feature. In some embodiments, a hydrogen plasma treatment, a thermal hydrogen treatment, or a reduction treatment may be used to reduce metal oxide on the metal substrate at the bottom of the feature. In some embodiments, an atomic layer clean with a chlorine-based plasma, a hydrogen fluoride (HF) vapor clean, an ammonium fluoride (NH4F) clean, or a process using other reducing agents may be used to reduce oxides from the feature surface.

[0093] In some embodiments, cleaning may use a molybdenum halide, such as MoCl5. In embodiments where exposure to a molybdenum halide is used to remove oxides, the conditions and / or dosage are such that metal nitrides are not etched. The features may be exposed to a continuous or pulsed flow of the molybdenum halide. An inert gas, such as argon (Ar), may be present, but a co-reactant, such as hydrogen (H2), is generally not present to prevent deposition. Exposure to the molybdenum halide may be performed in the same chamber as the subsequent fill operation.

[0094] A metal such as molybdenum can be selectively deposited at the feature bottom in operation 303 to form a metal film base, such as a molybdenum film base. As used herein, the phrases "metal film base" and "molybdenum film base" refer to a metal film (such as a molybdenum film) deposited at the bottom of the feature that serves as an underlayer for a subsequently formed metal or metal film. The Mo film base is deposited by introducing a Mo precursor and a reducing agent into the deposition chamber. In some embodiments, the reducing agent is flowed continuously while the Mo precursor is pulsed. In some embodiments, both the reducing agent and the Mo precursor are pulsed in an alternating sequence. The etching and deposition are controlled to selectively deposit Mo at the bottom of the feature, with deposition on the sidewall and field regions being absent (due to net etching) or present to a much lesser extent (due to more etching in these regions than at the feature bottom).

[0095] In some embodiments, MoCl, such as MoCl x As mentioned above, other MoX precursors are used in other embodiments. zPrecursors can be used. Examples of reducing agents used are described above. Non-oxygen-containing Mo precursors prevent oxidation of the surface of the feature. Non-oxygen-containing Mo precursors also prevent oxygen from being incorporated into the initial Mo layer. Oxidation increases the contact resistance. The absence of oxidation and oxygen incorporation ensures that the contact resistance remains low. In some embodiments, oxyhalide precursors such as MoOCl4 can be used. However, oxyhalides can introduce oxidation to the surface of the feature and increase the contact resistance.

[0096] In some embodiments, operation 303 involves operating in a mass transport limited regime. Because MoCl5 or other molybdenum halides can etch as well as react to deposit molybdenum, a concentration gradient of the molybdenum precursor within the feature can be used to achieve net deposition at the bottom of the feature and net etching or substantially less deposition near the feature opening. To accomplish this, a mass transport limited condition of the molybdenum precursor within the feature can be used.

[0097] The mass transport limited condition may be characterized, in part, by a concentration gradient of the reactant in the feature. In certain embodiments, the concentration of the reactant is lower inside the feature than near the opening, resulting in a faster etch rate near the opening than inside. This may result in net deposition at the bottom of the feature and no or substantially less deposition near the feature opening. The mass transport limited process condition may be achieved by supplying a limited amount of reactant to the processing chamber (e.g., using a low etchant flow rate relative to the cavity profile and dimensions) while maintaining a relatively high etch rate to consume some of the etchant as it diffuses into the feature. In certain embodiments, the concentration gradient is quite large, which may be caused by relatively high etch kinetics and relatively low etchant supply. In certain embodiments, the etch rate near the opening may also be mass transport limited. To achieve the mass transport limited regime, the relative amounts and / or concentrations of the molybdenum precursor and the reducing agent can be controlled along with the chamber pressure. Temperature can also be controlled to control the reaction rate.

[0098] During deposition, the temperature of the substrate and the pressure of the chamber can be controlled. In some embodiments, the substrate can be heated to between 350° C. and 550° C., such as between 400° C. and 500° C. In some embodiments, the chamber can be pressurized to at least 10 Torr, such as at least 30 Torr, or at least 50 Torr. In some embodiments, process parameters such as temperature and pressure can be used to control the selectivity.

[0099] In certain embodiments, by pre-treating with a first molybdenum-containing precursor followed by deposition with a second molybdenum-containing precursor, it is possible to selectively or preferentially etch the feature sidewalls without etching the feature bottom. In certain embodiments, etching of only one sidewall of a feature can also be achieved by selecting an appropriate molybdenum-containing precursor that has inherent properties that favor etching the feature sidewalls over etching the feature bottom.

[0100] In operation 304, a portion of the metal nitride layer or other conformal liner layer on the sidewall is etched. This may involve using the precursor used to deposit Mo in operation 304 as an etchant. In some embodiments, the precursor is a molybdenum halide precursor. As discussed above, the molybdenum halide precursor may be tailored to be used in both the deposition and etching processes.

[0101] In some embodiments, a molybdenum halide precursor such as MoCl5 can be used to selectively etch the TiN layer from the sidewall surface. TiN generally etches faster than Mo. The TiN layer on the bottom surface of the feature is protected by the Mo deposited in 303.

[0102] In some embodiments, operation 304 is performed after operation 303. An example of such an embodiment is further described below with reference to Figures 4A-4D. In some embodiments, the operations are controlled to be performed simultaneously or overlapping. An example of such an embodiment is further described below with reference to Figures 5A-5C.

[0103] After the Mo film base is deposited, the feature is filled with Mo in operation 305. The feature may be filled using either a molybdenum halide or a molybdenum oxyhalide precursor. Examples of molybdenum halide precursors include MoCl5. As indicated above, MoO y Xz Examples of precursors include MoO2Cl2, MoOCl4, MoOF4, MoO2Br2, MoO2I, and Mo4O 11 I. The features can be filled using ALD, plasma-enhanced ALD, chemical vapor deposition (CVD), or plasma-enhanced CVD. In the case of ALD or CVD, H2 can be the reducing agent. Mo can be the MoCl2 used to form the initial Mo layer. x Deposition is faster using molybdenum oxyhalide precursors than precursors such as MoO y X z The precursor is MoCl for non-plasma processes. x Mo can be deposited at a deposition rate at least twice that of the precursor. Plasma enhanced processes can be used to fill features at lower temperatures and / or increase deposition rates.

[0104] Notably, the method can be efficiently operated in a single chamber, simplifying the process flow.

[0105] 4A-4D show a schematic example of the process of FIG. 3. In FIG. 4A, a feature 401 is shown having a conformal TiN liner layer 415. The feature 401 has a bottom surface 405 and a lined feature sidewall surface 411. In FIG. 4A, the TiN liner includes a lined feature bottom surface 405 and a sidewall surface 411. In some embodiments, the conformal liner layer is titanium silicon nitride (TiSi x The TiN liner layer 415 may be or may include a metal silicide nitride (MSiN) layer. As mentioned above, other liner layers (e.g., WCN) may be used instead of TiN. In some embodiments, the conformal TiN layer 415 may be oxidized on the top surface of the layer. The feature 401 is formed in a dielectric material 413. An underlying stack 410 is below the feature bottom surface 405. In the illustrated example, the underlying stack 410 is a metal silicide nitride (MSiN) layer connected to a semiconductor layer 406, e.g., silicon (Si) or silicon germanium (SiGe). x N y ) layer 408 and a metal silicide layer (MSix ) 407. This stack 410 can be used in an S / D structure. x An example of a layer is titanium silicide (TiSi x ) Metal silicide nitride (MSi x N y An example of a titanium silicide nitride (TiSi x N y ). A conformal TiN liner layer 415 on the bottom surface 405 is used to protect the underlying stack 410 below the bottom surface of the feature. The TiN liner layer can act as a diffusion barrier, prevent etching of the underlying material, and prevent oxidation of the underlying material. Other protective layers may be used in alternative embodiments.

[0106] The feature 401 may be cleaned as described above with reference to operation 302. This may be done with a MoCl 5 solution, such as MoCl 6. x This may involve flowing a precursor into a chamber housing the substrate. In some embodiments, the precursor flow may be continuous. In yet some other embodiments, the flow may be MoCl x There may be multiple cycles of alternating precursor and purge gas administration. x The precursor effectively removes any oxides on the surface. For example, the TiN liner layer 415 is TiO x N y 3. Remove the oxide. This can be done without etching the TiN at all, or more than a negligible amount.

[0107] 4B illustrates feature 401 after a metal film base, such as a molybdenum film base 409, has been deposited on a bottom portion of feature 401 as described above in act 303 of FIG. xMoCl5 is deposited in the feature by reacting the precursor with a reactant such as H2. For ease of explanation, the description of Figures 4A-4D describes MoCl5 as the MoCl5 precursor and H2 as the reactant. However, other molybdenum halides and / or other co-reactants may be used.

[0108] When depositing Mo, a MoCl5 precursor is flowed into the feature and one or more of the partial pressure, reactant flow rate, reactant concentration, and reactant dosage time are controlled such that a concentration gradient of MoCl5 exists within the feature, with a higher concentration at the top of the feature and a lower concentration at the bottom of the feature.

[0109] At the bottom of the feature, MoCl5 reacts with H2 to form Mo on the bottom surface 405. The reaction is mass transport limited, allowing deposition without significant etching. At the top side of the feature, MoCl5 also reacts with H2. However, there is more MoCl5 than at the bottom, so the deposited Mo is etched away. In some embodiments, Mo is not deposited on the sidewalls. However, in some embodiments, a thin conformal layer is deposited on the sidewalls, as shown in FIG. 4B. There is a net deposition, but it is much less than at the bottom of the feature. This is called selective deposition of Mo at the bottom of the feature, forming a Mo film base.

[0110] In some other embodiments, the H reactant is flowed continuously while the MoCl precursor flow is pulsed, which facilitates selective deposition at the bottom of the feature, as illustrated in FIG.

[0111] The temperature of the substrate and the pressure of the chamber can be controlled. In some embodiments, the substrate can be heated to between 350° C. and 550° C., such as between 400° C. and 500° C. In some embodiments, the chamber can be pressurized to at least 10 Torr, such as at least 30 Torr, or at least 50 Torr.

[0112] FIG. 4C illustrates the feature 401 after a portion of the TiN liner layer 415 has been etched from the sidewall surface 411 as described with reference to operation 305 of FIG. 3. MoCl5 precursor is used to etch away Mo and the TiN liner layer 415 on the sidewall surface 411 in the upper portion of the feature 401. MoCl5 etches away the thin Mo on the sidewall surface 411 before etching away the TiN liner layer. In embodiments where Mo is not deposited on the sidewall surface 411, MoCl5 directly etches the TiN liner layer in the top portion of the feature. Due to its thickness, Mo 409 in the bottom portion of the feature 401 protects the TiN liner layer 415 from being etched away by the MoCl5 precursor. The TiN liner layer 415 remains on the bottom surface 405 to protect the underlying stack 410 during subsequent processing. As shown, the dielectric material 413 forms the sidewall surface 411 after etching. The remaining TiN layer 415 forms a "cup" around the Mo 409. Together, they protect the underlying stack 410 in subsequent processing and provide a layer onto which more Mo can be selectively deposited in a bottom-up process.

[0113] FIG. 4D shows the feature 401 after Mo gap filling of the feature. The feature 401 is filled with Mo filling 423. A TiN layer 415 remains between the Mo filling 423 and the underlying stack 410 at the bottom of the feature, but not between the Mo filling 423 and the dielectric 413. The feature 401 may be filled using an ALD process or a CVD process. The filling may be done with an oxygen-containing Mo oxyhalide precursor, an oxygen-free Mo halide precursor, or a combination thereof. The filling is a bottom-up fill, growing from a Mo film base 409 deposited at the bottom of the feature. In some embodiments, the filling may be performed in a single-stage deposition, where the filling continues using the same parameters as the initial filling, such as temperature and pressure. In some other embodiments, the filling may be performed in a multi-stage Mo deposition, where parameters may be changed during the deposition. For example, the deposition in the first stage may have a first temperature. After the first stage, the deposition can be followed by a second stage, with a second temperature higher than the first temperature. An increase in temperature can be used to increase Mo bulk loading and reduce processing time. In another example of a multi-stage deposition, the concentrations of Mo precursors and reactants can be changed in different stages. For example, a Mo halide precursor can initiate Mo loading, followed by a Mo oxyhalide precursor. The Mo oxyhalide precursor can be used to increase the processing rate.

[0114] 5A-5C show a second schematic example of the process of FIG. 3. FIG. 5A shows a feature 501 having a TiN liner layer 515 forming a bottom surface 505 and a sidewall surface 511. In FIG. 5A, the TiN liner includes a lined feature bottom surface 505 and a lined feature sidewall surface 511. In some embodiments, the TiN layer 515 may be oxidized on the top surface of the layer. The feature 501 is formed in a dielectric material 513. An underlying stack 510 is below the feature bottom surface 505. The underlying stack 510 is similar to the underlying stack 410 described above in FIG. 4A. In the illustrated example, the underlying stack 510 is a metal silicide nitride (MSi) layer connected to a semiconductor layer 506, e.g., silicon (Si) or silicon germanium (SiGe). x N y ) layer 508 and a metal silicide layer (MSi x ) 507. The feature 501 may be cleaned as described in operation 302. Cleaning may be used to remove any oxides on the surface of the feature 501.

[0115] FIG. 5B shows the feature 501 after operations 303 and 304 of FIG. 3 have been performed in the same operation. A metal film base, such as a molybdenum film base 509, is deposited while the TiN liner layer 515 is etched from the sidewall surface 511. The Mo film base 509 is deposited on the bottom surface 505 of the feature 501 and grows upward from there. In some embodiments, multiple cycles of alternating pulses of a molybdenum halide precursor and a reactant are used to deposit the Mo film base 509 and etch the TiN liner layer. For example, MoCl5 can be flowed without H2. The MoCl5 has a concentration gradient with more MoCl5 toward the top of the feature than the bottom. The MoCl5 etches the top of the feature, i.e., the sidewall surface 511, while a less concentrated MoCl5 remains in the feature. The flow of MoCl5 is stopped. Then a reactant, for example H2, is flowed. The MoCl5 remaining in the feature reacts with the H2 to deposit the Mo film base 509 at the bottom of the feature. This process is cycled, with more and more of the TiN liner layer 515 on the sidewall surface being removed after each cycle, and additional Mo film base 509 being deposited. In some embodiments, each cycle ends with a purge. For example, one of the following sequences can be cycled: Molybdenum halide precursors / reducing agents Molybdenum halide precursor / reducer / purge Of note, the two reactants can be reacted without a purge between the molybdenum halide precursor and the reducing agent. If a purge is used, it is generally incomplete leaving the molybdenum halide precursor in the feature available for reaction. In some embodiments, MoCl5 can be continuous while the H2 reactant is pulsed.

[0116] After this process is completed, the TiN liner layer is etched away from at least the top portion of the feature such that the sidewall surfaces 511 at the top portion are made of dielectric material 513 and a Mo film base 509 is formed on the TiN liner layer on the bottom surface 505. The TiN liner layer 515 remains at the bottom of the feature 501 to protect the underlying stack 510.

[0117] As described above in operation 303 of Figure 3, the temperature of the substrate and the pressure of the chamber can be controlled. In some embodiments, the substrate can be heated to between 350°C and 550°C, e.g., between 400°C and 500°C. In some embodiments, the chamber can be pressurized to at least 10 Torr, e.g., at least 30 Torr, or at least 50 Torr. In some embodiments, process parameters such as temperature and pressure can be used to control the selectivity.

[0118] FIG. 5C shows the feature 501 after Mo gap filling of the feature. The feature 501 is filled with Mo filling 523. The feature may be filled using a CVD or ALD process. The filling is a bottom-up fill, growing from an initial Mo film base 509 deposited at the bottom of the feature. This filling is similar to the filling described in 4D. A TiN layer 515 remains between the Mo filling 523 and the underlying stack 510.

[0119] FIG. 6 illustrates a schematic diagram of one embodiment of a process station 600 having a process chamber 602 for maintaining a low pressure environment. In some embodiments, multiple process stations may be included in a common low pressure process tool environment. For example, FIG. 7A illustrates one embodiment of a multi-station processing tool 700. In some embodiments, one or more hardware parameters of the process station 600 (including those described in detail below) may be programmatically adjusted by one or more computer controllers 650. In some other embodiments, the process chamber may be a single station chamber.

[0120] The process station 600 is in fluid communication with a reactant delivery system 601 for delivering process gases to a distribution showerhead 606. The reactant delivery system 601 includes a mixing vessel 604 for blending and / or conditioning process gases, such as a Mo precursor-containing gas, a hydrogen-containing gas, an argon or other carrier gas, or other reactant-containing gas, for delivery to the showerhead 606. One or more mixing vessel inlet valves 620 can control the introduction of process gases to the mixing vessel 604. In various embodiments, deposition of the initial Mo layer is performed at the process station 600, and in some embodiments, other operations, such as in-situ cleaning or Mo gap filling, can be performed at the same station or at another station of the multi-station processing tool 600, as further described below with respect to FIG.

[0121] As an example, the embodiment of FIG. 6 includes a vaporization point 603 for vaporizing the liquid reactant provided to the mixing vessel 604. In some embodiments, the vaporization point 603 can be a heated vaporizer. In some embodiments, the liquid precursor or liquid reactant may be vaporized in a liquid injector (not shown). For example, the liquid injector can inject pulses of the liquid reactant into the carrier gas flow upstream of the mixing vessel 604. In one embodiment, the liquid injector can vaporize the reactant by flushing the liquid from a higher pressure to a lower pressure. In another example, the liquid injector can spray the liquid into dispersed microdroplets that are then vaporized in a heated delivery pipe. Smaller droplets can vaporize faster than larger droplets, reducing the delay between liquid injection and complete vaporization. Faster vaporization can reduce the length of piping downstream from the vaporization point 603. In one scenario, the liquid injector can be attached directly to the mixing vessel 604. In another scenario, the liquid injector can be attached directly to the showerhead 606.

[0122] In some embodiments, a liquid flow controller (LFC) can be provided upstream of the vaporization point 603 to control the mass flow rate of the liquid that is vaporized and delivered to the process chamber 602. For example, the LFC can include a thermal mass flow meter (MFM) located downstream of the LFC. The plunger valve of the LFC can then be adjusted in response to a feedback control signal provided by a proportional integral derivative (PID) controller in electrical communication with the MFM. However, it may take a second or more to stabilize the liquid flow using feedback control. This may extend the time to dose the liquid reactant. Therefore, in some embodiments, the LFC can be dynamically switched between feedback and direct control modes. In some embodiments, this may be implemented by disabling the sense tubes of the LFC and the PID controller.

[0123] The showerhead 606 distributes process gases toward the substrate 612. In the embodiment illustrated in Figure 6, the substrate 612 is shown positioned below the showerhead 606 and resting on a pedestal 608. The showerhead 606 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to the substrate 612.

[0124] In some embodiments, the pedestal 608 can be raised or lowered to expose the substrate 612 to the volume between the substrate 612 and the showerhead 606. In some embodiments, the pedestal 608 can be temperature controlled via a heater 610. The pedestal 608 can be set to any suitable temperature, such as between about 300° C. and about 500° C., during operation to perform various disclosed embodiments. It will be appreciated that in some embodiments, the height of the pedestal can be programmatically adjusted by a suitable computer controller 650. At the end of a process stage, the pedestal 608 can be lowered to allow removal of the substrate 612 from the pedestal 608 during another substrate transfer stage.

[0125] In some embodiments, the position of the showerhead 606 can be adjusted relative to the pedestal 608 to vary the volume between the substrate 612 and the showerhead 606. Additionally, it will be appreciated that the vertical position of the pedestal 608 and / or the showerhead 606 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, the pedestal 608 may include a rotational axis for rotating the orientation of the substrate 612. It will be appreciated that in some embodiments, one or more of these exemplary adjustments can be implemented programmatically by one or more suitable computer controllers 650. The computer controller 650 may include any of the features described below with respect to the controller 650 of FIG. 6.

[0126] In some embodiments, where the plasma can be used as described above, the showerhead 606 and pedestal 608 are in electrical communication with a radio frequency (RF) power source 614 and matching network 616 to power the plasma. In some embodiments, the plasma energy can be controlled by controlling one or more of the process station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, the RF power source 614 and matching network 616 can operate at any suitable power to form a plasma having a particular composition of radical species. Similarly, the RF power source 614 can provide RF power of any suitable frequency. In some embodiments, the RF power source 614 can be configured to control the high and low frequency RF power sources independently of each other. Exemplary low frequency RF frequencies can include, but are not limited to, frequencies between 0 kHz and 900 kHz. Exemplary high frequency RF frequencies can include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz, or greater than about 13.56 MHz, or greater than 27 MHz, or greater than 80 MHz, or greater than 60 MHz. It will be appreciated that any suitable parameter may be adjusted, either discretely or continuously, to provide plasma energy for the surface reactions.

[0127] In some embodiments, the plasma can be monitored in-situ by one or more plasma monitors. In one scenario, the plasma power can be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, the plasma density and / or process gas concentration may be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters can be programmatically adjusted based on measurements from such in-situ plasma monitors. For example, OES sensors can be used in a feedback loop to provide programmatic control of the plasma power. It will be appreciated that in some embodiments, other monitors can be used to monitor the plasma and other process characteristics. Such monitors can include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0128] In some embodiments, instructions to the controller 650 may be controlled via input / output control (IOC) sequence instructions. In one example, instructions for setting conditions for a process step may be included in the corresponding recipe step of the process recipe. In some cases, the process recipe steps may be arranged in sequence such that all instructions for a process step are executed simultaneously with that process step. In some embodiments, instructions for setting one or more reactor parameters may be included in a recipe step. For example, a first recipe step may include instructions for setting a flow rate of an inert gas and / or reactant gas (e.g., Mo precursor), instructions for setting a flow rate of a carrier gas (such as argon), and a time delay instruction for the first recipe step. A second subsequent recipe step may include instructions for adjusting or stopping the flow rate of an inert gas and / or reactant gas, instructions for adjusting a flow rate of a carrier gas or purge gas, and a time delay instruction for the second recipe step. A third recipe step may include instructions for adjusting a flow rate of a second reactant gas such as H2, instructions for adjusting a flow rate of a carrier gas or purge gas, instructions for igniting a plasma, and a time delay instruction for the third recipe step. The fourth subsequent recipe step may include instructions to adjust or stop the flow of the inert and / or reactant gases, instructions to adjust the flow of the carrier or purge gases, and time delay instructions for the fourth recipe step. It will be understood that these recipe steps may be further subdivided and / or repeated in any suitable manner within the scope of the present disclosure.

[0129] Additionally, in some embodiments, pressure control for the process station 600 may be provided by a butterfly valve 618. As shown in the embodiment of Figure 6, the butterfly valve 618 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control for the process station 600 may also be adjusted by varying the flow rate of one or more gases introduced to the process station 600.

[0130] 7A and 7B show examples of processing systems. FIG. 7A shows an example of a processing system including multiple chambers. System 700 includes a transfer module 703. Transfer module 703 provides a clean vacuum environment to minimize the risk of contamination of the substrate as it moves between various modules during processing. Attached to transfer module 703 is a multi-station chamber 709 capable of performing in-situ cleaning and / or ALD processes as described above. The deposition of the initial Mo layer may be performed in the same or a different station or chamber as the subsequent Mo gap fill.

[0131] The chamber 709 can include multiple stations 711, 713, 715, and 717 that can sequentially perform operations according to the disclosed embodiments. For example, the chamber 709 can include a station 711 that is configured to perform a MoCl x Stations 713, 715, and 717 perform in-situ cleaning of the substrate using the precursor MoCl x In another example, chamber 709 can be configured for station 711 to perform an initial Mo layer deposition using a precursor and H2, and station 711 to perform an etch of a TiN layer. In another example, chamber 709 can be configured for station 711 to perform an in-situ clean, station 713 to perform an initial Mo layer deposition and simultaneous etch of a nitride liner layer, and stations 713 and 714 to perform bulk Mo deposition by ALD or CVD. In another example, chamber 709 can be configured for parallel processing of substrates, with each station performing multiple processes in sequence.

[0132] More than one station may be included in a multi-station chamber, e.g., 2-6, with appropriate distribution of operations. For example, a two-station chamber may be configured to perform an initial Mo layer deposition and nitride layer etch in a first station, followed by ALD of bulk Mo in a second station. The stations may include a heated pedestal or substrate support, one or more gas inlets, or a showerhead or distribution plate.

[0133] The transfer module 703 may also be attached to one or more single or multi-station modules 707. In some embodiments, pre-cleaning as described above may be performed in module 707, after which the substrate is transferred under vacuum to another module (e.g., another module 707 or chamber 709) for deposition.

[0134] The system 700 also includes one or more wafer source modules 701 where wafers are stored before and after processing. An atmospheric robot (not shown) in an atmospheric transfer chamber 719 can initially move the wafer from the source module 701 to a load lock 721. A wafer transfer device (typically a robot arm unit) in a transfer module 703 moves the wafer from the load lock 721 to a module attached to the transfer module 703 and between modules.

[0135] In some embodiments, deposition of Mo is performed in a first chamber that may be part of a system such as system 700, and CVD or PVD of W, Mo, or other conductive material deposited as an overburden layer is performed in another chamber that is not coupled to a common transfer module and may be part of a separate system.

[0136] FIG. 7B is an embodiment of the system 700 described in FIG. 7A. The system 700 of FIG. 7B includes a wafer source module 701, a transfer module 703, an atmospheric transfer chamber 719, and a load lock 721, as described above with reference to FIG. 7A. The system of FIG. 7B includes three single station modules 757. The system 700 may be configured to sequentially perform operations according to the disclosed embodiments. For example, the single station modules 757 include a first module 757a performing a cleaning operation, a second module 757b performing a MoCl2 cleaning operation, and a third module 757c performing a MoCl2 cleaning operation. x ALD of an initial Mo layer can be performed using a precursor, and a third module 757c can be configured to perform ALD of bulk Mo using a molybdenum oxyhalide precursor. In this example, an in-situ clean can optionally be performed in the second module 757b instead of or in addition to a pre-clean in the first module 757a. The station can include a heated pedestal or substrate support, one or more gas inlets, or a showerhead or distribution plate, as described above with reference to FIG.

[0137] In various embodiments, a system controller 729 is used to control process conditions during deposition. The controller 729 typically includes 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, stepper motor controller boards, etc.

[0138] The controller 729 can control all of the activity of the apparatus. The system controller 729 executes system control software that includes a set of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other parameters of a particular process. In some embodiments, other computer programs stored in memory devices associated with the controller 729 can be used.

[0139] Typically, there is a user interface associated with the controller 729. The user interface may include a display screen, a graphical software display of equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0140] The system control logic may be configured in any suitable manner. In general, logic may be designed or configured in hardware and / or software. Instructions for controlling the drive circuitry may be hard-coded or provided as software. Instructions may be provided by "programming." Such programming is understood to include any form of logic, including hard-coded logic in digital signal processors, application specific integrated circuits, and other devices having specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general purpose processor. The system control software may be coded in any suitable computer readable programming language.

[0141] The computer program code for controlling the Mo precursor pulse, hydrogen pulse, and argon flow, as well as other processes in the process sequence, can be written in any conventional computer readable programming language (e.g., assembly language, C, C++, Pascal, Fortran, etc.). The compiled object code or script is executed by the processor to perform the tasks identified in the program. Also, as shown, the program code may be hard coded.

[0142] The controller parameters relate to process conditions such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters are provided to the user in the form of a recipe and can be entered using a user interface.

[0143] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 729. Signals for controlling the process are output at analog and digital output connections of the deposition device.

[0144] The system software can be designed or configured in many ways. For example, various chamber component subroutines or control objects may be written to control the operation of the chamber components necessary to carry out a deposition process according to the disclosed embodiments. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0145] In some implementations, the controller 729 is part of a system, such a system may be part of the examples described above. Such a system may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling system operations before, during, and after processing of a semiconductor wafer or substrate. Such electronics may be referred to as a "controller" and may control various components or subparts of one or more systems. The controller 729 may be programmed to control any of the processes disclosed herein depending on the processing requirements and / or type of system. Such processes may include 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, fluid delivery settings, position and motion settings, wafer loading and unloading from tools and other transfer tools connected or interlocked with a particular system, and / or wafer loading and unloading from load locks.

[0146] Broadly, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, i.e., microcontrollers, that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. The operational parameters may, in some embodiments, be part of a recipe defined by a process engineer to accomplish one or more processing steps in the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0147] The controller 729 may in some embodiments be part of a computer integrated or coupled with the system or otherwise networked to the system, or may be coupled to such a computer, or a combination thereof. For example, the controller 729 may be in the "cloud" or may be all or part of a fab host computer system. This allows for remote access of wafer processing. The computer may allow remote access to the system to monitor the current progress of a fabrication operation, review the history of past fabrication operations, review trends or performance criteria from multiple fabrication operations, modify parameters of a current process, set processing steps following a current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network. Such a network may include a local network or the Internet. The remote computer may include a user interface that allows for the entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data. Such data identifies parameters for each processing step performed during one or more operations. The parameters may be specific to the type of process being performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, for example, by including one or more individual controllers that are networked together and cooperate toward a common purpose (such as the processes and controls described herein). An example of a distributed controller for such purposes would include one or more integrated circuits on the chamber that communicate with one or more integrated circuits that are remotely located (e.g., at the platform level or as part of a remote computer) and coupled to control the process in the chamber.

[0148] Exemplary systems may include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a PVD chamber or module, a CVD chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a tracking chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0149] As described above, depending on the process step or steps being performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used for material transport to and from tool locations and / or load ports within a semiconductor manufacturing factory.

[0150] The controller 729 may include a variety of programs. A substrate positioning program may include program code for controlling chamber components used to load a substrate onto a pedestal or chuck and control spacing between the substrate and other parts of the chamber, such as gas inlets and / or targets. A process gas control program may include code for controlling gas composition, flow rates, pulse times, and optionally flowing gases into the chamber prior to deposition to stabilize the chamber pressure. A pressure control program may include code for controlling the chamber pressure, for example, by adjusting a throttle valve in the chamber's exhaust system. A heater control program may include code for controlling current to 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.

[0151] Examples of chamber sensors that can be monitored during deposition include mass flow controllers, pressure sensors (such as pressure gauges), and thermocouples located in the pedestal or chuck. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain desired process conditions.

[0152] The implementation of the disclosed embodiments in single or multi-chamber semiconductor processing tools has been described above. The apparatus and processes described herein may be used in conjunction with lithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, solar panels, etc. Typically, but not necessarily, such tools / processes are used or performed together in a common fabrication facility. Lithographic patterning of films typically involves some or all of the following steps, each of which is enabled by many available tools: (1) applying photoresist to a workpiece (i.e., substrate) using a spin-on or spray-on tool; (2) curing the photoresist using a hotplate or furnace or UV curing tool; (3) exposing the photoresist to visible or UV or X-ray light using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist, thereby patterning the resist, using a tool such as a wet bench; (5) transferring the resist pattern to the underlying film or workpiece by using a dry etching tool or a plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

[0153] Although the foregoing embodiments have been described in some detail for clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Thus, the present embodiments should be considered as illustrative rather than restrictive, and the embodiments should not be limited to the details set forth herein.

Claims

1. 1. A method for filling a feature, comprising: providing a substrate comprising a feature having a feature bottom and a feature sidewall in a deposition chamber, the feature having a conformal liner layer comprising a lined feature bottom surface and a lined feature sidewall surface; selectively depositing a metal film on the bottom surface of the lined feature using a metal precursor and a reducing agent to form a metal film base; preferentially etching the conformal liner layer from the feature sidewalls in etching the metal film base with the metal precursor; depositing metal in the features on the metal film base using the metal precursor; A method comprising:

2. 2. The method of claim 1 , The method, wherein the reducing agent comprises hydrogen, hydrazine, ammonia, silane, disilane, diborane, or a combination thereof.

3. 2. The method of claim 1 , The method, wherein the conformal liner layer comprises titanium nitride, titanium silicide nitride, tungsten carbon nitride, or a combination thereof.

4. 2. The method of claim 1 , The method, wherein the metal precursor comprises a molybdenum halide, a molybdenum oxyhalide, or a combination thereof.

5. 2. The method of claim 1 , The method, wherein the forming of the metal film base and the etching of the conformal liner layer from the sidewalls are performed sequentially.

6. 2. The method of claim 1 , The method, wherein forming the metal film base and etching the conformal liner layer from the sidewalls are performed simultaneously.

7. 5. The method of claim 4, The method of claim 1, wherein the molybdenum halide comprises molybdenum dichloride, molybdenum trichloride, molybdenum tetrachloride, molybdenum pentachloride, molybdenum hexachloride, or molybdenum fluoride.

8. 5. The method of claim 4, The method of claim 1, wherein the molybdenum oxyhalide comprises molybdenum dioxide dichloride, molybdenum dioxide tetrachloride, molybdenum dioxide tetrafluoride, or molybdenum dioxide dibromide.

9. 2. The method of claim 1 , The method, wherein the temperature of the substrate during deposition is from about 350°C to about 550°C.

10. 2. The method of claim 1 , The method wherein the pressure in the deposition chamber is from about 10 Torr to about 50 Torr.

11. 2. The method of claim 1 , The method, wherein depositing includes filling the feature with a metal.

12. 12. The method of claim 11, The method, wherein the substrate further comprises a top surface, the top surface being coated with titanium disilicide.

13. 2. The method of claim 1 , The method further comprising pretreating and cleaning the conformal liner layer prior to deposition of the metal film.

14. 2. The method of claim 1 , The method, wherein preferentially etching comprises etching the conformal liner layer from the feature sidewalls without etching the metal film base.

15. 1. A method for filling a feature, comprising: providing a substrate comprising a feature having a feature bottom and a feature sidewall in a deposition chamber, the feature having a conformal liner layer comprising a lined feature bottom surface and a lined feature sidewall surface; selectively depositing a molybdenum film on the bottom surface of the lined feature using a molybdenum precursor and a reducing agent to form a molybdenum film base; preferentially etching the conformal liner layer with the molybdenum precursor in etching the molybdenum film base to remove the underlying feature sidewall surface; depositing molybdenum in the feature on the molybdenum film base using the molybdenum precursor; A method comprising:

16. 16. The method of claim 15, The method of claim 1, wherein the molybdenum precursor comprises a molybdenum halide or a molybdenum oxyhalide.

17. 17. The method of claim 16, The method of claim 1, wherein the molybdenum oxyhalide comprises molybdenum dioxide dichloride, molybdenum dioxide tetrachloride, molybdenum dioxide tetrafluoride, or molybdenum dioxide dibromide.

18. 17. The method of claim 16, The method of claim 1, wherein the molybdenum halide comprises molybdenum dichloride, molybdenum trichloride, molybdenum tetrachloride, molybdenum pentachloride, molybdenum hexachloride, or molybdenum fluoride.

19. 20. The method of claim 18, The method of claim 1, wherein the molybdenum halide comprises molybdenum pentachloride.

20. 16. The method of claim 15, The method, wherein preferentially etching comprises etching the conformal liner layer from the feature sidewalls without etching the metal film base.

21. 1. A method for filling a feature, comprising: providing a substrate comprising a feature having a feature bottom and a feature sidewall in a deposition chamber, the feature having a conformal liner layer comprising a lined feature bottom surface and a lined feature sidewall surface; selectively depositing a molybdenum film on a bottom surface of the lined feature using a first molybdenum precursor and a reducing agent to form a molybdenum film base; preferentially etching the conformal liner layer with a second molybdenum precursor in etching the molybdenum film base to remove the underlying feature sidewall surfaces; depositing molybdenum in the feature on the molybdenum film base using the first molybdenum precursor; A method comprising:

22. 22. The method of claim 21, The method, wherein preferentially etching comprises etching the conformal liner layer from the feature sidewalls without etching the metal film base.

23. 1. An apparatus for filling features on a substrate, comprising: at least one deposition chamber including a pedestal for holding a substrate comprising a feature having a feature bottom and feature sidewalls, the feature having a conformal liner layer with a lined feature bottom surface and a lined feature sidewall surface; at least one inlet port for delivering a vapor phase metal precursor to said deposition chamber; (a) depositing a molybdenum film on the bottom surface of the lined feature using a molybdenum precursor and a reducing agent; (b) preferentially etching the conformal liner layer with the molybdenum precursor in etching the underlying feature bottom surface and removing the underlying feature sidewall surface; (c) after (b), depositing molybdenum in the feature using the molybdenum precursor. a controller for controlling operation in the apparatus, the controller including machine readable instructions for: An apparatus comprising:

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