Diffusion barriers made from multiple barrier materials and related articles and methods

Abstract

Diffusion barriers effective to inhibit the elution and release of impurities present in solid materials from the surface of the solid material, as well as articles having a diffusion barrier on their surface, methods for preparing articles including a diffusion barrier on their surface, devices including articles having a diffusion barrier on their surface, and methods for using the articles and devices are described, wherein the diffusion barrier comprises at least two different barrier materials.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Application No. 62 / 945,602, filed December 9, 2019, the entirety of which is incorporated herein by reference for all purposes.

[0002] This specification relates to diffusion barriers that inhibit the release of impurities present in or from the surface of solid materials, as well as articles having a diffusion barrier on their surface, methods for preparing articles that include a diffusion barrier on their surface, devices that include articles having a diffusion barrier on their surface, and methods for using the articles and devices. [Background technology]

[0003] Semiconductor and microelectronic device manufacturing processes require highly clean processing environments to contain workpieces for processing. An example semiconductor processing step involves adding a quantity of high purity material to a semiconductor wafer that is made from high purity material and has a very precise chemical makeup.

[0004] An example of a common semiconductor process step is a deposition process in which precise amounts of desired (high-purity) material are deposited on a semiconductor substrate by chemical vapor deposition, atomic layer deposition, physical vapor deposition, etc. The processing environment, i.e., the environment in which the deposition occurs, is a vacuum environment that is required to be substantially free of contaminants, impurities, particulates, etc., because any of these undesirable materials could deposit on the substrate as unwanted impurities. The processing environment is contained by a process chamber that is evacuated except to contain the semiconductor substrate, the gaseous (including plasma, ionic) process materials necessary to perform the deposition, and minimal other materials or structures.

[0005] A different example of a semiconductor manufacturing process is the ion implantation process, in which ions are implanted into the surface of a semiconductor substrate to add to the material of the semiconductor substrate. A precise amount of implanted ions (sometimes called "dopants") are added to the semiconductor substrate material by bombarding the substrate with ions (e.g., by an ion beam or by ion immersion techniques). Again, the substrate must have a precise and pure chemical makeup (with respect to its intended components), and the ions (dopants) added to the substrate surface must also be highly pure. The processing environment is contained by a process chamber (e.g., an ion implantation chamber or a surface modification chamber) that is evacuated except for the semiconductor substrate, the ions for implantation, any other process fluids necessary to perform the implantation, and a minimum of other materials that might be considered impurities or contaminants.

[0006] Further examples of semiconductor manufacturing steps that are performed in highly clean processing environments that are as free from impurities as possible are annealing processes, etching processes (eg, plasma etching), cleaning steps, and the like.

[0007] The structures that define and house the processing environment of a semiconductor manufacturing tool are sometimes called process chambers (specific examples include anneal chambers, deposition chambers, ion implantation chambers, and etch chambers). A process chamber defines an interior space that contains the processing environment and further houses appropriate structures and devices for performing a particular semiconductor manufacturing process. A process chamber is made up of and houses components (also known as "process chamber components") that define the processing environment (e.g., sidewalls) and components that enable the process chamber and the semiconductor processing tool that houses the process chamber to perform a desired semiconductor manufacturing process. In addition to the sidewalls, the process chamber components include devices, equipment, and parts for containing or supporting a workpiece (e.g., a semiconductor wafer), delivering process materials to the chamber, or monitoring a process being performed in the chamber. Examples include chamber walls, flow conduits (e.g., flow lines, flow heads, etc.), fasteners, trays, supports (e.g., platens or "chucks" for supporting workpieces), ports, electronics, monitoring devices, as well as various other structures used to support workpieces, deliver or contain process materials to the process chamber, or perform or monitor processes being performed within the process chamber.

[0008] To reduce the amount of impurities in the processing environment, process chamber components should not introduce impurities into the processing environment, either before, during, or after use. Process chamber components should not contain surface impurities. Also, to the extent that the materials of the process chamber components contain impurities that can be released (e.g., outgassed) from the material over time, such as impurities adsorbed within the solid structure of the material, these impurities should not be released into the processing environment.

[0009] Various solid materials have been used to form process chamber components for use in semiconductor manufacturing tools. Useful materials generally include metals and metal alloys (e.g., aluminum (including aluminum alloys), stainless steel); minerals such as quartz; ceramics; glass; silicon materials; and various polymers. While these solid materials can be prepared to high levels of purity (low levels of impurity), even the highest levels of purity contain some amount of impurities. Common examples of known impurities are metals, sometimes referred to as "trace metal impurities," including Fe, Co, Ni, Zn, Mg, Mn, Cu, Na, Ca, K, etc. These trace metal impurities are known to diffuse through solid materials containing them and to be released from the material surface over time, especially at high temperatures. In semiconductor manufacturing environments, even such small amounts of these released impurities can be harmful to workpieces. Semiconductor processing is highly sensitive to these materials, as impurities such as trace metals affect the performance and yield of devices and manufacturing processes.

[0010] Therefore, to prevent the release of trace metal impurities from the solid material of the process chamber components into the semiconductor processing environment, process chamber components are prepared to include diffusion barriers on their surfaces, typically made from metal oxides. The diffusion barriers resist the passage of trace metal impurities from the surface of the solid material into the adjacent vacuum or directly onto the semiconductor workpiece. Practical diffusion barriers are designed to cover or "encapsulate" the process chamber components in an attempt to confine all impurities within the bulk material. Two example materials for these diffusion barriers are aluminum oxide (Al2O3) and tantalum oxide (Ta2O5). Summary of the Invention

[0011] Recent advances in semiconductor processing tools and methods have increased the need to prevent impurities, such as trace metal impurities, from being released into the processing environment from process chamber components of semiconductor processing tools.

[0012] One factor is that some types of semiconductor processing methods are being carried out at higher temperatures. For example, ion implantation methods have recently been carried out at even higher temperatures, including temperatures significantly above room temperature, e.g., greater than 300, 400, or 500 degrees Celsius. Even higher ion implantation processing temperatures, e.g., up to 600 or 700 degrees Celsius or higher, may be used in future processes. Similarly, deposition methods (e.g., chemical vapor deposition, physical vapor deposition, atomic layer deposition) and annealing steps may be carried out at temperatures above 400, 500, or 600 degrees Celsius. At these higher process temperatures, impurities present in the materials of the process chamber components experience higher rates of diffusion within the materials and higher rates of release from the surfaces of the materials.

[0013] Additionally, an increasing number of current techniques are increasing the level of sensitivity of semiconductor devices to trace metal impurities. The decreasing size of microelectronic device features and increasing performance expectations for higher speeds and reduced errors are reducing the allowable levels of impurities in finished devices.

[0014] The present disclosure relates to a diffusion barrier that inhibits the release of impurities from the surface of a solid material containing the impurities. The present disclosure also relates to a solid object including a diffusion barrier on its surface, a method for preparing a solid object including a diffusion barrier on its surface; a process chamber component, and processing equipment including a process chamber component including a solid object having a diffusion barrier; and methods for using such a process chamber component and processing equipment. The diffusion barrier may contain at least two different barrier materials and may be in the form of a multilayer diffusion barrier, a laminate, or a composite. One or more of the barrier materials may be an oxide, nitride, or fluoride of yttrium; one or more of the barrier materials may be an oxide, nitride, or fluoride of aluminum; one or more of the barrier materials may be an oxide, nitride, or fluoride of titanium; one or more of the barrier materials may be an oxide, nitride, or fluoride of zirconium; or one or more of the barrier materials may be an oxide, nitride, or fluoride of tantalum. When a barrier material is referred to as an "oxide," "nitride," or "fluoride" of one of the metals, these terms specifically refer to a nitrided oxide, nitrided fluoride, or oxide fluoride of one of the metals, e.g., M x O x N y , MOFs (where M is one of the listed metals), e.g., Y x O x N y Or it may include YOF etc.

[0015] In one aspect, the present disclosure relates to a diffusion barrier containing at least two barrier materials selected from an yttrium compound selected from yttrium oxide, nitride, or fluoride; an aluminum compound selected from aluminum oxide, nitride, or fluoride; a titanium compound selected from titanium oxide, nitride, or fluoride; a zirconium compound selected from zirconium oxide, nitride, or fluoride; and a tantalum compound selected from tantalum oxide, nitride, or fluoride.

[0016] In another aspect, the present disclosure relates to an article comprising a substrate having a diffusion barrier, the diffusion barrier comprising at least two barrier materials selected from an yttrium compound selected from yttrium oxide, nitride, or fluoride; an aluminum compound selected from aluminum oxide, nitride, or fluoride; a titanium compound selected from titanium oxide, nitride, or fluoride; a zirconium compound selected from zirconium oxide, nitride, or fluoride; and a tantalum compound selected from tantalum oxide, nitride, or fluoride.

[0017] The present disclosure may be more fully understood in consideration of the following description of various exemplary embodiments in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1A and 1B show examples of prior art solid objects with diffusion barriers. [Figure 2] 1A-1C show examples of solid objects having the described diffusion barriers. [Figure 3A] 1A-1C illustrate certain exemplary embodiments of solid objects having the described diffusion barriers. [Figure 3B] 1A-1C illustrate certain exemplary embodiments of solid objects having the described diffusion barriers. [Figure 3C] 1A-1C illustrate certain exemplary embodiments of solid objects having the described diffusion barriers. [Figure 4] FIG. 1 illustrates an example of an electrostatic chuck having a diffusion barrier as described. DETAILED DESCRIPTION OF THE INVENTION

[0019] While the present disclosure is susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and have been described in detail. It should be understood, however, that it is not intended to limit aspects of the disclosure to the particular exemplary embodiments described. Rather, it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

[0020] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include their plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense including "and / or" unless the content clearly dictates otherwise.

[0021] The term "about" generally refers to a range of numbers that are considered equivalent to the recited value (e.g., have the same function or result). In many instances, the term "about" can include numbers that are rounded to the nearest significant figure.

[0022] Numerical ranges expressed using endpoints include all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0023] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered the same. The detailed description and the drawings, which are not necessarily to scale, depict exemplary embodiments and are not intended to limit the scope of the invention. The exemplary embodiments shown are intended as examples only. Selected features of any exemplary embodiment may be incorporated into additional embodiments, unless expressly stated to the contrary.

[0024] The following description relates to a diffusion barrier effective to inhibit the release of impurities from the surface of a solid object containing the impurities, or a solid object having such a diffusion barrier on its surface; a method for preparing a solid object having a diffusion barrier on its surface; a process chamber component, and processing equipment including a process chamber component including a solid object having a diffusion barrier; and methods of using such process chamber components and processing equipment.

[0025] Diffusion barriers may serve as part of structures, articles, devices, or components of process equipment or apparatus where there is a need or desire to prevent impurities (e.g., trace metal impurities) present within a solid object from being released from the solid object into an adjacent or connected environment where the presence of the impurities or other materials is undesirable, adverse, or potentially harmful. Diffusion barriers are disposed at interfaces or surfaces within the solid object and have a composition and structure to effectively inhibit or prevent impurities present within the solid object as adsorbed impurities from passing from within the solid object to the adjacent environment by diffusion and outgassing.

[0026] In an exemplary application, the diffusion barrier, in conjunction with a semiconductor processing tool and semiconductor processing method, can help prevent impurities present in a process chamber component of the semiconductor processing tool from being released from the surface of the process chamber component into the processing environment. The release of impurities places the impurities in the highly clean processing environment contained by the processing tool. Once present in the processing environment, the impurities are undesirable because they may come into contact with and become incorporated into a workpiece (e.g., a semiconductor wafer) being processed using the semiconductor processing tool.

[0027] Examples of solid materials used as solids in process chamber components of semiconductor processing tools include metals (including alloys such as stainless steel and aluminum alloys), ceramics, glasses, polymers, and quartz. Depending on their specific composition, these solid materials contain one or more of a variety of different types of trace metal impurities, such as iron, cobalt, nickel, zinc, copper, magnesium, manganese, sodium, calcium, potassium, boron, beryllium, aluminum, titanium, vanadium, selenium, strontium, arsenic, molybdenum, cadmium, tin, tungsten, mercury, lead, barium, and antimony. These impurities can diffuse from the solid material and occur (e.g., "outgas") from the surface of the solid material into the adjacent environment or directly onto the semiconductor workpiece. This is especially true at the high temperatures and high vacuum conditions sometimes used in certain semiconductor processing methods.

[0028] A diffusion barrier, as described above, includes two or more different barrier materials that simultaneously inhibit the diffusion and release of two or more different types of impurities from a solid object. According to an exemplary diffusion barrier, one of the two barrier materials may be effective to act as a barrier to a first impurity, and a second of the two barrier materials may be effective to act as a barrier to at least one additional impurity (referred to as a "second impurity") that is different from the first impurity, e.g., less effective than the first barrier material in terms of diffusion rate through the barrier material.

[0029] The diffusion barrier is made of at least two different barrier materials, each of which is an oxide, nitride, or fluoride of yttrium, aluminum, titanium, zirconium, or tantalum (these materials specifically include nitride-oxide, nitride-fluoride, and oxide-fluoride compounds of any metal). More specifically, an exemplary diffusion barrier may be made of at least two different barrier materials, each of which is a metal-containing compound, where the metal is yttrium, aluminum, titanium, zirconium, or tantalum; for example, the diffusion barrier may be made of two different compounds selected from yttrium compounds, aluminum compounds, titanium compounds, zirconium compounds, and tantalum compounds, where each compound is an oxide, fluoride, or nitride of the metal. One of the barrier materials may be an oxide, nitride, or fluoride of yttrium; one of the barrier materials may be an oxide, nitride, or fluoride of aluminum; one of the barrier materials may be an oxide, nitride, or fluoride of titanium; one of the barrier materials may be an oxide, nitride, or fluoride of zirconium; or one of the barrier materials may be an oxide, nitride, or fluoride of tantalum. In all cases, the terms metal oxide, metal fluoride, and metal nitride refer to metal oxynitride, metal fluoride, or metal oxyfluoride, e.g., Y x O x N y or YOF, and similar compounds of aluminum, titanium, zirconium, and tantalum.

[0030] The two different barrier materials of the diffusion barrier may be based on two different metals (yttrium, aluminum, titanium, zirconium, or tantalum); for example, the diffusion barrier may be a combination of an aluminum-containing compound and an yttrium-containing compound, such as alumina and yttria, or an aluminum-containing compound and a zirconium-containing compound, such as alumina and zirconia. Alternatively, the two different barrier materials may each contain the same metal; for example, the barrier material may include two different metal-containing compounds both based on the same metal selected from yttrium, aluminum, titanium, zirconium, or tantalum. For example, the diffusion barrier may be a combination of alumina and aluminum fluoride, or a combination of yttria and yttrium fluoride, or titania and titanium fluoride, etc.

[0031] Two or more different barrier materials can be selected to provide a diffusion barrier with effective barrier properties against multiple different impurities present in the solid material of the solid object. Different types of solid material (e.g., aluminum, stainless steel, glass, or ceramic) contain different combinations of trace metal impurities, and exemplary metal alloys, glasses, or ceramics may contain two or more of iron, cobalt, nickel, zinc, copper, magnesium, manganese, sodium, calcium, potassium, etc. Different barrier materials may be effective as barriers to prevent the passage of one or more of these impurities, but may be less effective or ineffective at preventing the passage of other impurities (from the list described or otherwise). Diffusion barriers herein may include a first barrier material that is effective at acting as a barrier material to prevent the passage of a first impurity, but is ineffective or much less effective at preventing the passage of a different (second) impurity, and the diffusion barrier may include a different (second) barrier material that is effective (e.g., more effective than the first barrier material) at preventing the passage of the second impurity.

[0032] By way of example only, some solid materials may contain a first impurity from the group of iron, cobalt, nickel, or copper and a second impurity from the group of magnesium, sodium, calcium, or potassium. A particular barrier material may be effective as a barrier to one or more impurities from the first group, but not to any of the second group. Other barrier materials may be effective as a barrier to one or more impurities from the second group. A useful diffusion barrier herein may include a first barrier material that is an effective barrier to iron, cobalt, nickel, or copper, and a second barrier material that is effective as a barrier to magnesium, sodium, calcium, or potassium. More specifically, alumina may be effective as a barrier material to iron, cobalt, nickel, or copper, but not as a barrier to magnesium, sodium, calcium, or potassium. An effective diffusion barrier may include alumina as a first barrier material to inhibit the outflow of iron, cobalt, nickel, or copper, and a second barrier material (e.g., a titanium compound, a zirconium compound, a yttrium compound, or a tantalum compound) that is effective as a barrier to magnesium, sodium, calcium, or potassium.

[0033] If the first barrier material is adequately effective as a barrier material against the first impurity but not adequately effective as a barrier material against the second impurity, the second barrier material may be more effective as a barrier against the second impurity. The second barrier material may be at least twice, preferably five or ten times, more effective as a barrier material against the second impurity than the first barrier material. With respect to the diffusion rate of the impurity through the barrier material, the diffusion rate of the second impurity through the second barrier material may be half, one-fifth (20%), or one-tenth (10%) of the diffusion rate of the second impurity through the first barrier material.

[0034] The diffusion barrier may also include a third barrier material that functions to improve the general or overall barrier properties of a diffusion barrier containing the first and second barrier materials. When used in combination with the barrier properties of the first two, the third barrier material may reduce the diffusion rate of one or more impurities. In certain examples, the third barrier material may enhance the effectiveness of the diffusion barrier against at least one impurity compared to an equivalent diffusion barrier containing only the first and second barrier materials. The third barrier material added to a diffusion barrier made from the first and second barrier materials may reduce the diffusion rate of the impurity by at least 10, 20, or 50% compared to an equivalent diffusion barrier containing only the first and second barrier materials.

[0035] The described diffusion barriers or diffusion barrier materials achieve at least useful standards of performance required for a diffusion barrier in a particular environment, application, or impurity. When used in a semiconductor processing tool, the described diffusion barriers or diffusion materials can preferably demonstrate effectiveness as a diffusion barrier based on an elemental impurity concentration gradient across the diffusion barrier layer. For example, at an effective operating temperature of a semiconductor processing tool (e.g., one identified herein), the diffusion barrier generates a concentration gradient measured across the diffusion barrier layer. A concentration gradient, particularly in the context of semiconductor processing tools, can be defined as the difference in the concentration of an elemental impurity on one side of the diffusion barrier compared to the concentration of the same elemental impurity on a second side of the diffusion barrier, i.e., the difference in the concentration of the impurity in a solid object having a diffusion barrier compared to the concentration of the same elemental impurity at the surface of the diffusion barrier layer adjacent to a gaseous atmosphere (e.g., a process chamber of a semiconductor processing tool). In an exemplary semiconductor processing tool, an exemplary diffusion barrier can provide a concentration gradient within a factor of 10, 100, or 1000, when considering the concentration of an impurity at the diffusion barrier layer surface of a process chamber relative to the concentration of the impurity in the solid object. Specifically, a useful or preferred barrier can provide an impurity concentration in a process chamber that is 1 / 10, 1 / 100, or 1 / 1000 of the concentration of the same impurity above the process chamber at operating temperatures.

[0036] When used in various types of process chamber components, for example, as a coating on a process chamber component for use in a particular processing method, it may be desirable for the diffusion barrier to also exhibit one or more additional physical properties, such as chemical resistance or chemical inertness, desired electrical properties, and stability over time at high operating temperatures, such as the operating temperatures of the semiconductor processing tools described herein.

[0037] In certain applications, a high degree of resistance to chemical degradation, i.e., chemical inertness, may be desirable for process chamber components used at high temperatures, particularly in process chambers of plasma etching tools, ion implantation tools, or other types of semiconductor processing tools that use reactive process materials such as plasma, ionic materials, bases or acids, or other reactive vapors. To this end, process chamber components, including the described diffusion barriers, disposed on a solid object may optionally include an additional layer of chemically resistant material adjacent to the surface of the solid object or the diffusion barrier. Examples of chemically resistant materials, including chemically resistant layers, useful in semiconductor processing tools are known, and certain specific examples include, but are not limited to, metal oxides and metal fluorides, such as aluminum oxide formed by anodization; yttrium oxide; multilayer combinations of aluminum oxide and yttrium oxide; and the like.

[0038] The described diffusion barriers can preferably exhibit a highly amorphous morphology. For example, as determined by use of X-ray diffraction techniques, useful or preferred diffusion barriers herein can have significantly reduced impurity diffusion rates in a substantially amorphous diffusion barrier layer, with the full width at half maximum (FWHM) of the diffusion barrier XRD peak being wider than 2.5 degrees 2θ by X-ray diffraction.

[0039] The described diffusion barriers can be particularly useful or advantageous when used at relatively high processing temperatures where the diffusion rate of trace metal impurities increases. Various semiconductor processing methods are performed at relatively high process temperatures, such as temperatures above 300 or 400 degrees Celsius. Ion implantation methods may be performed at temperatures above 300, 400, or 500 degrees Celsius, or even up to 600 or 700 degrees Celsius or higher. Deposition methods (e.g., atomic layer deposition, chemical vapor deposition, physical vapor deposition, etc.) as well as annealing processes may be performed at temperatures above 300, 400, 500, or 600 degrees Celsius. At these relatively high processing temperatures, the diffusion rate of trace metal impurities present in the solid materials of the process chamber components increases. With increased diffusion rates, a greater amount of impurities diffuse through and are released from the surface of the solid material and enter the processing environment of the semiconductor processing tool. Therefore, at these relatively high processing temperatures, an effective diffusion barrier is of great value.

[0040] The described diffusion barriers may be provided on the surface of a solid object and may have the form of a deposited coating made from two or more of the described barrier materials. The barrier materials may be present in any form, examples being "multilayer" forms containing two to several (e.g., 2-10) distinct and identifiable layers of different barrier materials; "laminate" forms containing a larger number of distinct and identifiable layers of different barrier materials, such as numbers in the range of tens, hundreds, or even thousands; and "composite" materials containing two or more different types of barrier material, where the different barrier materials are not formed into complete or continuous layers (e.g., islands of deposited material).

[0041] Generally, by way of non-limiting example, the thickness of a single distinct layer of the diffusion barrier may be less than 1 nanometer, e.g., about 0.1, 0.5, 1, 2, 5, or 10 nanometers, up to 100, 500, 800, or 900 nanometers (0.9 microns). The total thickness of the diffusion barrier may be in the range of 10 nanometers to 1000 nanometers (1 micron).

[0042] In a diffusion barrier comprising distinct layers of different barrier materials, e.g., a multilayer or laminate diffusion barrier, each individual layer can exhibit a coefficient of thermal expansion (CTE) that allows for stability of the multilayer diffusion, e.g., over a lifetime of temperature cycling. Desirably, the CTE of each layer may be similar to that of an adjacent layer, such as within no more than 100, 75, 50, 20, or 10 percent. In the case of a multilayer or laminate diffusion barrier, all layers of the diffusion barrier preferably have a CTE within no more than 100, 75, 50, 20, or 10 percent of that of any adjacent layer, i.e., two adjacent layers for all inner layers, and a single adjacent layer for upper and lower layers. These selections allow the layers of the multilayer diffusion barrier to be arranged and ordered to take into account the potentially high thermal stresses imposed on the diffusion barrier during use.

[0043] Exemplary diffusion barriers, referred to herein as "multilayer" diffusion barriers, include diffusion barriers made from two or more, e.g., 2, 3, 5, or up to 10, 20, or 30, individual layers, each made from a single barrier material, with the diffusion barrier-containing layer being made from at least two different barrier materials. Each layer is continuous, has a distinct thickness, and is made from a single barrier material having a relatively high level of purity, e.g., at least 90, 95, 98, or 99% purity by weight of the single barrier material described herein. The layers of the diffusion barrier can be of any useful thickness, such as thicknesses ranging from 1, 2, 5, or 10 nanometers up to 10, 100, 500, 800, or 900 nanometers, e.g., two to five layers each having a thickness in the range of 2-10 nanometers. The total thickness of this type of diffusion barrier can be any useful thickness, with exemplary thicknesses ranging from 5 or 10 up to 500, 750, or 1000 nanometers.

[0044] The thickness of each layer of the multilayer diffusion barrier may be the same, approximately the same, or different. An example of a multilayer diffusion barrier may include a barrier material layer exhibiting a pattern of different thicknesses, such as three repeating layers A, B, and C, each having a different thickness, repeated for (N) repetitions to achieve a thickness of (5 nm A, 20 nm B, and 2 nm C) x N, where N may be from 1 to 10. Another example may be a single barrier material layer A having a thickness of 50 nm combined with multiple repeating barrier material layers B and C, three layers A, B, and C, repeated for a number of repetitions (N), to achieve a thickness of (5 nm B and 3 nm C) x N, where (N) may be from 1 to 10.

[0045] An exemplary multilayer diffusion barrier containing 2 to 10 individual layers may be fabricated from two or more different barrier materials having a high level of purity selected from yttrium oxide, nitride, or fluoride; aluminum oxide, nitride, or fluoride; titanium oxide, nitride, or fluoride; zirconium oxide, nitride, or fluoride; and tantalum oxide, nitride, or fluoride. Multilayer diffusion barriers can be prepared by any method in which multiple layers are individually deposited, for example, on a solid material, such as by physical vapor deposition, chemical vapor deposition, atomic layer deposition, any derivative of such deposition methods, or other known coating and deposition techniques.

[0046] Other examples of diffusion barriers containing multiple layers, e.g., many layers, such as tens or hundreds of layers, may be called laminates. A laminate may contain layers of at least two different barrier materials and may have 8 to 1000 total layers, each having a thickness in the range of, for example, 0.1 to 10 nanometers.

[0047] 1 , a typical process chamber component 100 is shown that includes a diffusion barrier 104 disposed on a surface of a solid object 102 made from a solid material (e.g., metal, metal alloy, glass, quartz, ceramic, etc.). The solid material of the solid object 102 contains impurities, such as trace metal impurities. The diffusion barrier 104 is a layer made from a single oxide compound, such as aluminum oxide, that prevents the release of the trace metal impurities from the solid object 102.

[0048] FIG. 2 illustrates an exemplary process chamber component 101 (or another type of device or article) made from a solid object 102 and a diffusion barrier 114 that includes two or more different barrier materials described herein, according to various embodiments.

[0049] 3A, according to some embodiments, the process chamber component 101 may be made from a solid object 102 and a diffusion barrier 114 made from two or three different barrier materials formed in multiple (three as shown) layers. Layers 124, 126, and 128 may be made from at least two different barrier materials, and each of the different layers may be made from a single barrier material. For example, each of layers 124, 126, and 128 may be made of a different barrier material, where one or more of the barrier materials may be an oxide, nitride, or fluoride of yttrium; one or more of the barrier materials may be an oxide, nitride, or fluoride of aluminum; one or more of the barrier materials may be an oxide, nitride, or fluoride of titanium; one or more of the barrier materials may be an oxide, nitride, or fluoride of zirconium; or one or more of the barrier materials may be an oxide, nitride, or fluoride of tantalum. Each layer may preferably have a high purity, for example, at least 90, 95, 98, or 99% purity by weight of the barrier material. Each layer of barrier material may be continuous across the surface of the solid object 102 and may have a thickness ranging from less than 1 nanometer, for example, about 1, 2, 5, or 10 nanometers, up to 10, 100, 500, 800, or 900 nanometers (0.9 microns).

[0050] Other layers of different types of barrier or non-barrier materials are not excluded and may be present, but are not necessarily necessary or preferred.

[0051] 3B shows another exemplary process chamber component 101 provided in accordance with an embodiment of the present disclosure. The chamber component 101 includes a solid object 102 and a diffusion barrier 114 made of two or more different barrier materials formed into a large number (e.g., tens, hundreds, or thousands) of individual layers, each of which is a single barrier material. Layers 134, 136, and 138 may be made of at least two different barrier materials, with each layer being made of a single barrier material. For example, each of layers 134, 136, and 138 may be made of a different barrier material, with each of the different layers being made of a single barrier material. One or more of the barrier materials may be an oxide, nitride, or fluoride of yttrium; one or more of the barrier materials may be an oxide, nitride, or fluoride of aluminum; one or more of the barrier materials may be an oxide, nitride, or fluoride of titanium; one or more of the barrier materials may be an oxide, nitride, or fluoride of zirconium; or one or more of the barrier materials may be an oxide, nitride, or fluoride of tantalum. Each layer may preferably have a high purity, for example, at least 90, 95, 98, or 99% purity by weight of the barrier material. Each barrier layer may be continuous across the surface of the solid object 102 and may have a thickness of less than 1 nanometer, for example, from about 0.1, 0.5, 1, 2, 5, or 10 nanometers, up to 10, 15, or 20 nanometers.

[0052] Other layers of different types of barrier or non-barrier materials are not necessarily excluded and may be present, but are not necessarily required or preferred.

[0053] The diffusion barrier 114 of FIG. 3B containing tens, hundreds, or thousands of layers may be referred to as a “stack” diffusion barrier. A stack diffusion barrier may be applied to the surface of the solid object 102 by a series of atomic layer deposition steps, sequentially forming each individual layer made of a single barrier material by exposing the surface to a series of gaseous precursor materials. Each successive amount of deposited barrier material is considered a “layer.” As an example, a series of atomic layer deposition steps may be performed, each step using a single precursor material to form a single barrier layer. The series includes depositing at least two different types of barrier material layers to form different layers of the stack. A stack diffusion barrier includes individual “layers” due to a multi-step process in which distinct layer-deposited barrier materials are deposited, for example, in a patterned order.

[0054] The stack is considered to be made up of different layers produced by each atomic layer deposition step, even though it may be difficult to distinguish the individual "layers" of different deposited materials using known techniques. In some stack coatings, the individual layers may be detectable using a tunneling electron microscope. Each layer may be considered to constitute a "monolayer," a term used in chemical deposition techniques to refer to the amount of deposited material deposited on the surface of a substrate or a previous ALD layer such that the deposited material saturates the reactive sites on the substrate or previous ALD layer. A monolayer has a thickness of only a few atoms, i.e., a single layer of atoms or molecules that covers the surface by associating with a limited number of reactive sites on the surface, creating a monolayer having a thickness of about 2, 3, or 5 atoms or less.

[0055] FIG. 3C illustrates an example of another process chamber component 101 provided in accordance with an embodiment of the present disclosure. The chamber component 101 includes a solid object 102 and a diffusion barrier 114. The diffusion barrier 114 is in the form of a composite (144) made of two or more different barrier materials formed into a "composite" form of incomplete layers. Similar to a "stack" diffusion barrier, the composite can also be formed by atomic layer deposition through a series of atomic layer deposition steps, but the amount of each material deposited during each step in the series is such that it does not produce a uniformly deposited continuous layer of the deposited barrier material. For example, a barrier material may be deposited by atomic layer deposition steps that deposit an amount of barrier material having a thickness less than the roughness of the surface onto which the barrier material is deposited. When deposited sequentially, the deposited amounts of different barrier materials form a "composite" material made of the different deposited materials, but do not form discrete or continuous layers, e.g., not even a monolayer having a thickness of 1 to 5 atomic layers.

[0056] The diffusion barrier 114 in the form of a composite 144 may be made from two or more barrier materials as described. One or more of the barrier materials may be an oxide, nitride, or fluoride of yttrium; one or more of the barrier materials may be an oxide, nitride, or fluoride of aluminum; one or more of the barrier materials may be an oxide, nitride, or fluoride of titanium; one or more of the barrier materials may be an oxide, nitride, or fluoride of zirconium; or one or more of the barrier materials may be an oxide, nitride, or fluoride of tantalum. The composite may preferably have a high purity, such as by containing at least 90, 95, 98, or 99% by weight of the two or more barrier materials made to form the diffusion barrier. The total thickness of the diffusion barrier may also be any useful thickness, such as a thickness in the range of 10 to 1000 nanometers.

[0057] A currently preferred example of a diffusion barrier made from two (in this example, only two) different barrier materials may have two layers, multiple layers (e.g., 3-10), or may be a laminate or composite of two barrier materials. Individual layers of the multilayer diffusion barrier or laminate may be made from barrier materials selected from alumina, yttria, zirconia, and titania. For example, a multilayer or laminate diffusion barrier made using only two barrier materials may be made from alternating layers of alumina and yttria, alumina and zirconia, alumina and titania, yttrium and zirconia, or yttria and titania. For a diffusion barrier containing only two total layers (one layer made from each barrier material), each layer may be about 50 nanometers, e.g., 40-60 nanometers. For a diffusion barrier containing 3-10 layers, each layer may be from 1, 5, or 10, up to 20-40 nanometers, e.g., 10-30 nanometers. These or composite diffusion barriers may have a total thickness of 50 to 150 nanometers, for example 80 to 120 nanometers. The ratio of the number of layers of each of the two barrier materials may be about 1:1, for example 40:60 to 60:40, or 45:55 to 55:45.

[0058] A currently preferred example of a diffusion barrier made from three (in this example, only three) different barrier materials may have three layers, multiple layers (e.g., 4-10), or may be a laminate or composite of three different barrier materials. Individual layers of the multilayer diffusion barrier or laminate may be made from barrier materials selected from alumina, yttria, zirconia, and titania. For example, a multilayer, laminate, or composite diffusion barrier made using only three barrier materials may be made from patterned layers of alumina, zirconia, and yttria; alumina, titania, and yttria; zirconia, titania, and yttria; or zirconia, alumina, and titania. For a diffusion barrier containing only three total layers (one layer made from each barrier material), each layer may be about 25-70 nanometers, e.g., 30-60 nanometers. For a diffusion barrier containing 4-10 layers, each layer may be 20-45 nanometers, e.g., 15-40 nanometers. These or composite diffusion barriers may have a total thickness of 50 to 200 nanometers, for example 80 to 160 nanometers. The amount of different barrier materials within the diffusion barrier may be about 33% by weight of each barrier material, for example 30 to 40% by weight of each barrier material within the diffusion barrier.

[0059] The diffusion barriers herein may be useful when placed on any article or surface containing impurities that are desirably prevented from diffusing out of the article. The described diffusion barriers may be particularly useful as barriers to prevent impurities from escaping from solid objects in articles, devices, or components (e.g., "process chamber components") that are part of semiconductor processing tools, such as ion implantation tools, or types of deposition tools, such as chemical vapor deposition, physical vapor deposition, atomic layer deposition, etc.

[0060] Without limiting the scope of this specification, a semiconductor processing tool can be of any type, including a vacuum-operated process chamber in which semiconductor substrates are processed. The process chamber operates at a high level of vacuum to house semiconductor devices and enables the processing of the semiconductor devices by exposing the devices to high-purity process materials, such as plasma, ions, or molecular compounds in gas or vapor form, that are applied to the semiconductor substrate. The process chamber must contain components and surfaces useful for transporting, holding, securing, supporting, or moving substrates into, out of, and within the process chamber. The process chamber must also contain a structural system effective for flowing, delivering, and removing process materials (e.g., plasma, ions, gaseous deposition materials, etc.) into and out of the vacuum contained in the process chamber. Examples of these different types of process chamber components include sidewalls or liners that define the interior surfaces of the process chamber, as well as flow heads (showerheads), shields, trays, supports, nozzles, valves, conduits, stages for handling or holding substrates, wafer handling fixtures, chamber liners (i.e., sidewalls), ceramic wafer carriers, wafer holders, susceptors, spindles, chucks, rings, baffles, and various types of fasteners (screws, nuts, bolts, clamps, rivets, etc.). Any of these or other types of process chamber components can be adapted to include a diffusion barrier as described herein to inhibit or prevent the passage of impurities from the solid materials that form the process chamber components into the vacuum environment of the process chamber.

[0061] The process chamber components may have surfaces of any shape or form, such as flat, planar surfaces (for liners or sidewalls), or may additionally or alternatively have physical shapes or forms including features that would be considered to have high aspect ratios, including openings, apertures, channels, tunnels, threaded screws, threaded nuts, porous membranes, filters, three-dimensional networks, pores, etc. The atomic layer deposition techniques for providing certain exemplary diffusion barriers described can be effective in providing uniform, high-quality diffusion barriers on such structures, including articles having structures with aspect ratios of at least 20:1, 50:1, 100:1, 200:1, or 500:1.

[0062] The described diffusion barriers may be useful for process chamber components of any type of semiconductor processing tool, as well as for processing tools operating at any temperature and other process conditions. The described diffusion barriers may be particularly useful when disposed on process chamber components of semiconductor processing tools operating at high temperatures, such as temperatures significantly above room temperature. As an example, newer ion implantation methods are performed at ever-higher temperatures, including temperatures exceeding 300, 400, 500, 600, or 700 degrees Celsius. Various deposition techniques (e.g., chemical vapor deposition, physical vapor deposition, atomic layer deposition) and annealing steps may be performed at temperatures of 400, 500, or 600 degrees Celsius or higher. When performed using a semiconductor processing tool, these methods expose the tool's process chamber components to the same high temperatures, increasing the diffusion rate of trace metal impurities in the solid material of the process chamber components. Effective barrier materials, as described herein, may be particularly useful for these processing tools and processing methods.

[0063] Process chamber components may be made from a type of solid material (also referred to as a "solid object" or "substrate") sometimes referred to as a "vacuum-compatible substrate." In general, examples of solid materials useful as vacuum-compatible substrates may include ceramic materials, metals (including alloys such as aluminum alloys and solid steel), glass, quartz, and polymeric materials. Ceramic materials useful as vacuum-compatible substrates include alumina, silicon carbide, and aluminum nitride. Examples of metals and metal alloys include stainless steel and aluminum. Vacuum-compatible substrates may also be quartz, sapphire, dielectric materials, conductive materials, silica, fused silica, fused quartz, silicon, anodized aluminum, zirconium oxide, and plastics such as certain plastics used in the semiconductor industry, such as polyetheretherketone (PEEK) and polyimide.

[0064] As a single example, the described diffusion barriers may be effective when included on or near the surface of an electrostatic chuck of an ion implantation device, which may be a beam-type ion implantation device or a plasma ion immersion implantation device. As is known, an electrostatic chuck may be housed within the process chamber of the ion implantation device to support and maintain the position of a semiconductor wafer during the ion implantation process.

[0065] Various general and specific designs of electrostatic chucks are known. Referring to Figure 4, a typical electrostatic chuck (200) may be formed from multiple layers, including a base layer 210 of solid dielectric (e.g., ceramic) material, an adhesive bonding layer, and a second dielectric layer 214. The top surface 220 may include optional embossments 230, which may also be made from a dielectric material. Various other structures and devices may also be present, including electrical devices such as conductive layers (e.g., ground layers, charge dissipation layers).

[0066] 4 may include a diffusion barrier 240 on top of the electrostatic chuck, for example, at or near the top surface of the second dielectric layer 214. The diffusion barrier 240 may be effective in preventing the passage of impurities from the dielectric layer 214 into the atmosphere of the ion implantation device containing the electrostatic chuck 200.

[0067] Diffusion barrier 240 may be of any composition and form described herein, for example, a multi-layer diffusion barrier, a laminate, or a composite.

[0068] While this specification often refers to the use of diffusion barriers in semiconductor manufacturing processes (e.g., ion implantation, deposition steps), semiconductor processing tools, and related process chamber components, the described diffusion barriers are not limited to these items and applications. Various other solid objects for use in other environments, such as high vacuum environments, can also benefit from the described diffusion barriers to prevent impurities from passing from the solid object to the vacuum environment.

Claims

1. 1. A diffusion barrier comprising at least two different barrier materials, the at least two different barrier materials comprising: a yttrium compound selected from yttrium oxide, nitride or fluoride; an aluminum compound selected from an aluminum oxide, nitride or fluoride; a titanium compound selected from the group consisting of an oxide, nitride, or fluoride of titanium; a zirconium compound selected from zirconium oxides or nitrides, or A tantalum compound selected from tantalum oxides or nitrides. and at least two metal compounds of the at least two different barrier materials are different from each other, at least one of the two different barrier materials is a fluoride, and at least one of the at least two different barrier materials is amorphous; Diffusion barrier.

2. 10. The diffusion barrier of claim 1, wherein one of the at least two different barrier materials is effective to act as a barrier to a first trace metal impurity and a second of the at least two different barrier materials is effective to act as a barrier to a second trace metal impurity different from the first trace metal impurity.

3. a first barrier material effective as a diffusion barrier to one or more of the following impurities: iron, cobalt, nickel, and copper; a second barrier material effective as a diffusion barrier against one or more of the impurities Zn, Mg, Mn, Na, Ca, and K; 10. The diffusion barrier of claim 1 comprising:

4. 10. The diffusion barrier of claim 1, wherein the diffusion barrier comprises two to five layers of at least two different barrier materials, each layer having a thickness in the range of 2 to 10 nanometers.

5. 5. The diffusion barrier of claim 4, wherein the diffusion barrier comprises two or three layers selected from a zirconia layer, a titania layer, a yttria layer, a tantala layer, and an alumina layer.

6. 5. The diffusion barrier of claim 4, wherein the diffusion barrier comprises at least two of a plurality of zirconia layers, a plurality of titania layers, a plurality of yttria layers, a plurality of tantala layers, and a plurality of alumina layers.

7. 1. An article comprising a substrate having a diffusion barrier, the diffusion barrier comprising: a yttrium compound selected from yttrium oxide, nitride or fluoride; an aluminum compound selected from an aluminum oxide, nitride or fluoride; a titanium compound selected from the group consisting of an oxide, nitride, or fluoride of titanium; a zirconium compound selected from zirconium oxides or nitrides, or A tantalum compound selected from tantalum oxides or nitrides. and at least two different barrier materials, including any one of at least two metal compounds of the at least two different barrier materials are different from each other, at least one of the two different barrier materials is a fluoride, and at least one of the at least two different barrier materials is amorphous; Goods.

8. 8. The article of claim 7, wherein one of the two different barrier materials is effective to act as a barrier to a first trace metal impurity and a second of the two different barrier materials is effective to act as a barrier to a second trace metal impurity different from the first trace metal impurity.

9. a first barrier material effective as a diffusion barrier to one or more of the following impurities: iron, cobalt, nickel, and copper; a second barrier material effective as a diffusion barrier against one or more of the impurities Zn, Mg, Mn, Na, Ca, and K; 8. The article of claim 7, comprising:

10. The article of claim 7 , wherein the article is a process chamber component of a semiconductor manufacturing tool.

Images