YTTRIUM FLUORIDE MEMBRANE AND METHOD FOR PREPARING AND USING THE SAME - Patent application

Abstract

Yttrium fluoride compositions, including deposited films, e.g., coatings, containing yttrium fluoride; methods for preparing yttrium fluoride compositions and deposited film coatings containing yttrium fluoride; and substrates having deposited film coatings containing yttrium fluoride thereon, as well as methods and apparatuses including the substrates.

Description

[Technical field]

[0001] SUMMARY This specification relates to yttrium fluoride films that include protective coatings, methods for preparing yttrium fluoride films, substrates and surfaces that include yttrium fluoride films, and methods for preparing and using yttrium fluoride films. [Background technology]

[0002] Manufacturing methods for semiconductor and microelectronic devices require various processing steps involving highly reactive process materials, such as plasma. Exemplary processes that use reactive process materials include plasma etching, plasma deposition, and plasma cleaning. These processes are carried out inside a process chamber that contains a workpiece (e.g., a "substrate") and the reactive process materials. The process chamber also includes various structures and components (also known as "process chamber components") that define the process chamber and items within or associated with the process chamber that are necessary for operation. These process chamber components can include chamber walls, flow conduits (e.g., flow lines, flow heads, piping, tubing, etc.), fasteners, trays, supports, and other structures and devices used to support the workpiece or deliver or contain reactive process materials to the process chamber.

[0003] To be used as part of a process chamber, a process component should be resistant to the reactive process materials used within the process chamber, and should not be degraded or damaged by contact with the process materials in such a manner as to generate debris or particulates that could potentially contaminate the workpiece being processed, particularly as incorporated in the process being performed.

[0004] Process chamber components used in semiconductor processing equipment for manufacturing semiconductors and microelectronic devices are often made of a solid material (the "substrate" or "base"), such as a metal (e.g., stainless steel, aluminum alloys that may be anodized, tungsten), mineral, or ceramic material. The substrate is usually coated with a protective layer that is more resistant to reactive process materials than the substrate material. Traditionally, such protective thin film coatings have typically been disposed on the substrate by a variety of useful methods, typically by the process of anodization (e.g., to produce anodized aluminum), spray coating, or deposition techniques (e.g., physical vapor deposition (PVD), chemical vapor deposition (CVD), or atomic layer deposition (ALD)). Summary of the Invention

[0005] As described herein, yttrium fluoride ("YF3") can be prepared as part of a deposited film by converting yttrium oxide of the deposited yttrium oxide film to yttrium fluoride. The resulting yttrium fluoride film can have a relatively high concentration of fluorine and a relatively low concentration of oxygen. Due to the relatively high fluorine content (e.g., compared to fluorinated metal oxides such as YOF), the yttrium fluoride film can be effective as a material for a protective coating.

[0006] Previous and current processes containing relatively high amounts of fluorine (e.g., greater than YOF), which may be useful for preparing deposited films as protective coating materials, have been difficult to use due to the complexities of working with fluorine chemistry, including, inter alia, environmental and occupational health and safety, compatibility of highly fluorinated raw materials with processing equipment, abatement and disposal procedures, etc.

[0007] Yttrium fluoride has previously been used for purposes other than as a protective coating material. As one example, yttrium fluoride has been formed into a transparent, low refractive index film for use as an optical coating. Previous yttrium fluoride films have been formed by sputtering techniques that are unable to deposit yttrium fluoride uniformly and continuously on three-dimensional surfaces, especially those having features with high aspect ratios.

[0008] The described yttrium fluoride materials are different from previous deposited yttrium fluoride films, such as those formed by sputter deposition techniques. The yttrium fluoride films herein can be formed as continuous films on three-dimensional surfaces, including surfaces with high aspect ratio structures, for example. Because the yttrium fluoride films herein are formed by converting yttrium oxide to yttrium fluoride by fluoro-annealing the yttrium oxide, the yttrium fluoride films herein may also contain an amount of oxygen, especially in the lower part of the film thickness, and may contain varying concentrations of fluorine, oxygen, or both along the thickness (depth) of the thin film.

[0009] The methods herein are particularly useful for forming yttrium fluoride from deposited yttrium oxide films formed by atomic layer deposition by converting the yttrium oxide to yttrium fluoride. Similar methods have not been shown to be effective with other (non-yttrium) metal oxide materials, or with yttrium oxide or other metal oxide deposited films formed by deposition methods other than atomic layer deposition.

[0010] As used herein, "deposited thin film," "thin film," or "film," or the like, refer to a coating of material deposited on the surface of a substrate by a deposition process, such as atomic layer deposition, and also refer to modified forms or derivatives of those deposited films, including films that are first deposited and then chemically modified by a fluorination process.

[0011] In one aspect, a coated substrate is described herein. The coated substrate includes a substrate and a yttrium fluoride film formed on the substrate. The yttrium fluoride film includes yttrium, fluorine, oxygen, a surface, a thickness, and a yttrium fluoride portion extending from the surface through a portion of the thickness having an oxygen concentration of less than 20 percent (atomic). The concentration of fluorine in the yttrium fluoride film varies with thickness.

[0012] In another aspect, described herein is a method of preparing yttrium fluoride, the method including depositing a yttrium oxide film on a surface by atomic layer deposition and exposing the yttrium oxide film to fluorine and high temperature to convert the yttrium oxide of the yttrium oxide film to yttrium fluoride. [Brief description of the drawings]

[0013] [Figure 1] 1 is a graph showing X-ray diffraction data for coatings herein. [Diagram 2] 1 shows a graph of X-ray diffraction data for the described yttrium fluoride films. [Diagram 3] Examples of methods and specific method steps useful for forming the described yttrium fluoride thin films are provided. [Figure 4] 1 shows an example of a substrate having a thin coating of yttrium fluoride on its surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following description relates to deposited thin films containing yttrium fluoride (sometimes referred to as "yttrium fluoride thin films" or alternatively as "yttrium fluoride films"), protective coatings including yttrium fluoride thin films, and substrates having a surface and a yttrium fluoride thin film deposited thereon. The substrate surface may be a highly three-dimensional surface, e.g., a surface having at least one structure exhibiting a high aspect ratio.

[0015] The present disclosure also relates to methods for preparing and using yttrium fluoride thin films, including yttrium fluoride thin films that function as protective coatings.

[0016] According to the method described herein, a deposited thin film containing yttrium fluoride can be formed from a deposited yttrium oxide thin film by converting at least a portion of the yttrium oxide of the deposited yttrium oxide thin film to yttrium fluoride. For example, the method may include depositing yttrium oxide as a thin film on a surface by atomic layer deposition (ALD) techniques. A fluoro-annealing step then converts at least a portion of the yttrium oxide of the deposited film to yttrium fluoride. The fluoro-annealing step is performed at a relatively high temperature for a time period during which a significant amount of the yttrium oxide is converted to yttrium fluoride (YF3) instead of remaining in the form of yttrium oxide fluoride (YOF).

[0017] Yttrium fluoride is an inorganic material consisting of yttrium and fluorine, with or nearly so chemical composition of YF3. As used herein, yttrium fluoride thin films or portions thereof contain primarily yttrium and fluorine atoms, with the majority of yttrium and fluorine being in the form of yttrium fluoride, or YF3. Yttrium fluoride thin films can also contain amounts of oxygen, as well as combinations of various elements of yttrium, fluorine, and oxygen, such as yttrium oxide fluoride (YOF). However, preferred yttrium fluoride thin films or portions thereof can contain amounts (concentrations) of oxygen below the amount of oxygen that would be present in a composition called yttrium oxide fluoride (YOF), for example, 20 percent or less oxygen measured at a particular location along the thickness (depth) of the yttrium fluoride thin film.

[0018] The entire yttrium fluoride thin film contains substantially only yttrium, fluorine, oxygen, possibly a relatively small amount of carbon ("C") (e.g., up to 4 or 5 atomic percent carbon), and no more than minor or substantially no amounts of other materials throughout its thickness. The described yttrium fluoride thin films may consist of Y, F, O, and C (e.g., up to 4 or 5 atomic percent carbon), or may consist essentially of Y, F, O, and C, for example, containing Y, F, O, and C (e.g., up to 5 or 4 percent (atomic) carbon) and no more than 1, 0.5, 0.1, 0.05, or 0.01 atomic percent of any material different from Y, F, O, and C.

[0019] The described yttrium fluoride thin film formation method is found to be particularly effective for producing thin films containing high concentrations of yttrium fluoride, especially for forming thin films on three-dimensional and high aspect ratio surfaces. The described method does not directly deposit yttrium fluoride (YF3) itself on the surface. Instead, the described method forms a yttrium oxide thin film on a substrate by atomic layer deposition, and converts at least a portion of the yttrium oxide of the deposited thin film to yttrium fluoride by a fluoro-annealing process, thereby forming yttrium fluoride.

[0020] These processes have been shown to be particularly effective in forming thin films containing high concentrations of yttrium fluoride, as compared to alternative methods of first depositing a yttrium oxide thin film by a different deposition method (e.g., chemical vapor deposition, physical vapor deposition, or variations thereof) followed by a fluoro-annealing step. The described yttrium fluoride thin films can be prepared by converting a deposited yttrium oxide thin film to yttrium fluoride using a relatively high temperature fluoro-annealing step, e.g., a fluoro-annealing step carried out at a temperature of at least 300° C. Comparable fluoro-annealing techniques at relatively high temperatures that attempt to convert yttrium oxide to yttrium fluoride have not been as effective as when performed on yttrium oxide deposited by a different deposition technique, such as physical vapor deposition ("PVD") or chemical vapor deposition ("CVD").

[0021] These particular processes have also been determined to be more effective at forming highly fluorinated metal fluoride materials, i.e., YF3, compared to methods of forming other types of metal fluorides from other metals by comparable deposition and fluoro-annealing processes. The described high temperature fluoro-annealing processes have not been very effective at converting other metal oxides to metal fluorides, even if the metal oxides are deposited by atomic layer deposition techniques. Specifically, fluoro-annealing processes at relatively high temperatures have been found to be less effective at converting metal oxide materials, such as zirconium oxide, titanium oxide, or aluminum oxide, to fluorinated oxide materials (zirconium fluoride, titanium fluoride, or aluminum fluoride), even if the metal oxides are deposited by atomic layer deposition techniques.

[0022] In a preferred method, due to the thermal stresses experienced by the deposited yttrium oxide thin film during the relatively high temperature fluoro-annealing process, an intermediate layer (e.g., a "buffer layer") may be disposed on the substrate surface between the substrate surface and the deposited yttrium oxide thin film. The intermediate layer (described in more detail below) may be effective to allow the deposited yttrium oxide thin film to be processed by the fluoro-annealing process at relatively high fluoro-annealing temperatures without cracking or physically damaging the deposited yttrium oxide thin film due to the stresses generated during the high temperature fluoro-annealing process.

[0023] Advantageously, the method herein allows yttrium fluoride thin films to be prepared exclusively by gas-phase techniques, namely atomic layer deposition and fluoro-annealing techniques.Previous methods for forming yttrium fluoride films rely on sputtering techniques, which are considered to be "line-of-sight" techniques that are ineffective for uniformly depositing yttrium fluoride on three-dimensional surfaces or surfaces that contain high aspect ratio structures.The method described herein allows deposition thin films containing yttrium fluoride to be efficiently and effectively formed on three-dimensional surfaces, including surfaces with high aspect ratio structures.

[0024] The examples of deposited thin films herein can be distinguished from previous sputtered yttrium fluoride thin films in that they are uniformly deposited on surfaces that are substantially three-dimensional or have high aspect ratio structures. Alternatively, or in addition, the deposited thin films herein can be distinguished from sputtered yttrium fluoride thin films by the inclusion of oxygen in portions of the film, particularly portions at depths below the surface of the film. Sputtered yttrium fluoride thin films are formed only from yttrium and fluorine and do not contain more than substantially no oxygen.

[0025] In a related sense, yttrium fluoride thin films herein contain amounts or concentrations of fluorine and oxygen that are non-uniform across the thickness (depth), i.e., contain concentrations of fluorine and oxygen that vary by a measurable amount along the thickness (depth) of the deposited film. Yttrium fluoride films formed by sputtering do not exhibit substantial variation in fluorine or oxygen concentration along the thickness of the deposited film.

[0026] The described films can be produced by a method including forming a deposited yttrium oxide thin film on a substrate surface by atomic layer deposition. The substrate surface may optionally include an intermediate layer as described elsewhere herein before the yttrium oxide thin film is deposited. Yttrium oxide (Y2O3, also known as "yttria") is prepared from and contains yttrium and oxygen in a relative amount (atoms) of about 2:3 (yttrium:oxygen). Methods for forming yttrium oxide by atomic layer deposition are known. See, for example, U.S. Patent Publication No. 2018 / 0202047.

[0027] In an exemplary method, a deposited yttrium oxide thin film can be formed on a substrate by atomic layer deposition, depositing yttrium oxide on a substrate surface maintained at a temperature in the range of 100° C. to 350° C., e.g., 140° C. to 200° C. The deposited yttrium oxide thin film can be formed to any useful thickness, such as a thickness ranging from about 0.01 microns (10 nm) to 0.25 microns (250 nm), 0.5 microns (500 nm), 0.75 microns (750 nm), or up to or exceeding 1 micron. After depositing the yttrium oxide thin film, the deposited yttrium oxide thin film is treated with a fluorine annealing step ("fluoro-annealing" step) that converts at least a portion of the total amount of yttrium oxide in the deposited thin film to yttrium fluoride. The fluoro-annealing step is performed at a temperature and time effective to not merely fluorinate the yttrium oxide to form yttrium oxyfluoride (or "yttrium oxide fluoride", YOF). The temperature and time of the fluoro-annealing step are sufficient to convert at least a substantial portion of the yttrium oxide of the deposited yttrium oxide thin film, particularly in the surface portion of the deposited yttrium oxide thin film, to yttrium fluoride (YF3). According to a useful or preferred method, at least the outer surface or "surface portion" of the yttrium oxide thin film, including a portion of the thickness of the film between the surface and a depth of at least 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 nanometers, is converted to YF3 that contains a small amount of oxygen or is substantially free of oxygen, e.g., less than 15 atomic percent oxygen, less than 10, 5, or 3 atomic percent oxygen, as measured by X-ray photoelectron spectroscopy throughout the thickness of the surface portion, and contains a large amount of fluorine, e.g., at least 45 atomic percent oxygen, at least 50, at least 55, or at least 60 atomic percent fluorine, as measured by X-ray photoelectron spectroscopy throughout the thickness of the surface portion. In some embodiments, the surface portion can have a thickness of at least 10 nanometers, less than 5 percent (atomic) oxygen, as measured by X-ray photoelectron spectroscopy throughout the thickness of the surface portion, and at least 60 percent (atomic) fluorine, as measured by X-ray photoelectron spectroscopy throughout the thickness of the surface portion.In some embodiments, the surface portion can have a thickness of at least 50 nanometers, less than 15 percent (atomic) oxygen, as measured by X-ray photoelectron spectroscopy throughout the thickness of the surface portion, and at least 50 percent (atomic) fluorine, as measured by X-ray photoelectron spectroscopy throughout the thickness of the surface portion.

[0028] Methods for converting yttrium oxide to yttrium oxyfluoride (YOF) by a fluoro-annealing step performed at a temperature below 300° C. have been previously described. See U.S. Patent Publication No. 2018 / 0202047. The methods described herein include specific features of a fluoro-annealing step performed at a temperature above 300° C. to successfully convert yttrium oxide at least at a surface portion of the deposited yttrium oxide thin film to contain a high concentration of yttrium fluoride (YF3) containing a small amount of oxygen, substantially free of oxygen, or containing a small amount of yttrium oxide fluoride (YOF) or substantially free of yttrium oxide fluoride (YOF).

[0029] A useful and preferred fluoro-annealing technique involves exposing a yttrium oxide surface, for example the surface of a yttrium oxide thin film deposited by atomic layer deposition, to a molecular fluorine source vapor at a temperature at which the fluorine from the molecular fluorine source vapor reacts with the yttrium oxide (aka "yttrium oxide layer") of the deposited yttrium oxide thin film to form yttrium fluoride at and beneath the surface of the deposited yttrium oxide thin film.

[0030] As used herein, a "molecular fluorine source vapor" is a non-plasma (i.e., molecular) fluorine-containing chemical molecule in vapor (gas) form that is not considered a plasma. A "plasma" is a non-solid vapor phase composition that contains a high density of ionic fragments derived from one or more plasma precursor compounds that have been intentionally exposed to energy (e.g., from a radio frequency power source) for the purpose of breaking down the plasma precursor compounds into ions and using the ions to process a workpiece. In contrast to a plasma, a useful or preferred molecular fluorine source vapor may contain less than 1×10E-5 atomic percent of ionized material, e.g., less than 1×10E-6 atomic percent of ionic species.

[0031] The molecular fluorine source vapor can be provided to the process chamber for forming the yttrium fluoride thin film by any method or from any useful and effective source or location. In a useful or preferred method, the molecular fluorine source vapor can be generated in situ, i.e., during the process of forming the yttrium fluoride thin film on the surface of the substrate and in the process chamber used to form the yttrium fluoride thin film on the surface. The molecular fluorine source vapor can be generated in situ from a non-gaseous fluorine source by heating the non-gaseous fluorine source to turn the molecules of the non-gaseous fluorine source into a gas, i.e., molecular vapor. The non-gaseous fluorine source can be a liquid or solid fluorine-containing material, and the heating step generates the gaseous form of the molecules without causing significant decomposition or ionization of the molecules of the liquid or solid fluorine source. The useful or preferred gaseous form of the molecules can be at least 99.9999 atomic percent of the molecules, i.e., the molecules of the liquid or solid fluorine-containing material that are not chemically altered. The gaseous form of the molecule may contain less than 1×10E−5 atomic percent of ionized or decomposed material, such as less than 1×10E−6 atomic percent of ionic species.

[0032] The heating process to generate molecular fluorine source vapor is different from the process to generate plasma used in various semiconductor processing steps. In general, the plasma generation process involves applying one or more forms of energy to a plasma source, typically a gaseous chemical, to ionize the plasma source and chemically break down the molecules of the plasma source to generate ionic fragments of the molecules. The energy may be thermal energy (high temperature), electromagnetic radiation such as RF (radiation) (generated by a radio frequency power source), or a combination of these.

[0033] As a specific comparison, the heating step used herein to generate molecular fluorine source vapor is different from the step of generating a fluorine-containing plasma for use in a semiconductor processing tool for the steps of plasma etching, plasma cleaning, or "seasoning" the process chamber of the semiconductor processing tool. An example of a plasma generation step different from the heating step described herein is described in U.S. Patent No. 5,756,222, which describes a fluorine-containing plasma generated in a reaction chamber designed for plasma etching or plasma cleaning processes. The plasma is prepared by exposing a fluorine precursor to RF power.

[0034] The fluoro-annealing step can be performed in a process chamber at an elevated temperature by placing a substrate having a surface including a deposited yttrium oxide thin film deposited thereon by atomic layer deposition inside a process chamber in a removable, temporary, non-operating manner; by distributing a molecular fluorine source vapor into the process chamber or generating a molecular fluorine source vapor within the process chamber by heating a non-gaseous fluorine source to cause molecules of the non-gaseous fluorine source to become a gas, i.e., a vapor, within the process chamber; and by increasing the temperature of the process chamber, the substrate, the deposited yttrium oxide thin film, the molecular fluorine source vapor, or a combination thereof, to cause a reaction between the fluorine of the molecular fluorine source vapor and the yttrium oxide of the deposited yttrium oxide thin film to convert at least a portion of the yttrium oxide to yttrium fluoride.

[0035] During the fluoro-annealing step, the process chamber may contain process materials including molecular fluorine source vapor, optionally a non-vapor fluorine source, and one or more substrates having a deposited yttrium oxide thin film deposited on the surface by atomic layer deposition techniques. The interior space and atmosphere of the chamber need not be evacuated or depressurized, and may contain a certain amount of atmospheric air. For the fluoro-annealing step, it is not necessary to exclude air or oxygen, nor to introduce an inert gas (purge gas, e.g., N2) into the process chamber. The process chamber need not contain, and may exclude, any other additional gaseous or liquid process materials other than air and molecular fluorine source vapor, and may exclude other gaseous materials, such as inert gases or gaseous co-reactants that may be used in the gaseous atmospheres of other semiconductor processing steps.

[0036] The process chamber need not, and preferably does not, contain other workpieces that are not part of a semiconductor processing tool and are otherwise being processed, such as semiconductor devices, microelectronic devices, or precursors thereof. The process chamber also does not require or include the use of means for generating a plasma, such as a radio frequency power source, or means for applying an electrical potential (voltage) to components or workpieces.

[0037] Useful process chambers preferably include a temperature control for controlling the temperature within the chamber; a means for controlling the composition and purity of the environment within the chamber, e.g., pressure control, filters, etc.; components for temporarily housing and supporting within the chamber one or more substrates, each having a deposited yttrium oxide thin film thereon, for a period of time useful for converting the yttrium oxide of the deposited yttrium oxide thin film to yttrium fluoride; and components for controlling the composition of the atmosphere within the process chamber, including supplying and controlling the amount and concentration of a molecular fluorine source within the process chamber.

[0038] According to certain useful or preferred exemplary fluoro-annealing methods, the molecular fluorine source vapor may be a gaseous fluorinated or perfluorinated organic compound, such as a fluorinated or perfluorinated alkane or alkene, any of which may be linear or branched. Examples include, among others, CF4, C2F4, C3F6, C4F8, CHF3, C2H2F2, C2F6, HF, CH3F, each of which is in molecular form, i.e., substantially non-ionic, and is not treated (by the application of energy other than heat) to decompose or form a plasma.

[0039] According to another useful or preferred exemplary method, the molecular fluorine source vapor can be a gaseous fluorinated polymer that has not been treated with energy to form a plasma. The gaseous fluorinated polymer can be derived from a non-gaseous (e.g., liquid or solid) fluorinated polymer, which is desirably converted to yttrium fluoride by a fluoro-annealing process, for example, by heating the non-gaseous fluorinated polymer in the presence of a deposited yttrium oxide thin film in a process chamber.

[0040] The fluorinated polymer may be any fluorinated polymer that is effective according to the described method for forming yttrium fluoride from a deposited yttrium oxide thin film present on the surface of a substrate. Examples of useful fluorinated polymers include homopolymers and copolymers that include polymerized fluoroolefin monomers and optionally non-fluorinated comonomers. The polymer may be fluorinated (i.e., partially fluorinated), perfluorinated, or may contain non-fluorine halogen atoms such as chlorine. The molecular fluorine source may be a liquid or solid at room temperature, but becomes a vapor at the temperature of the process chamber used according to the described method.

[0041] Non-limiting examples of specific fluoropolymers include C1-C 10Examples of such copolymers include polymerized perfluoroalkyl ethylenes having perfluoroalkyl groups; polytetrafluoroethylene (PTFE); tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymers (PFA); tetrafluoroethylene / hexafluoropropylene copolymers (FEP); tetrafluoroethylene / perfluoro(alkyl vinyl ether) / hexafluoropropylene copolymers (EPA); polyhexafluoropropylene; ethylene / tetrafluoroethylene copolymers (ETFE); polytrifluoroethylene; polyvinylidene fluoride (PVDF); polyvinyl fluoride (PVF); polychlorotrifluoroethylene (PCTFE); ethylene / chlorotrifluoroethylene copolymers (ECTFE); or combinations thereof.

[0042] The described fluoro-annealing step can be performed at any temperature effective to react fluorine from the fluorine source vapor with the yttrium oxide of the deposited yttrium oxide thin film to convert at least a portion of the deposited yttrium oxide thin film to yttrium fluoride (e.g., at the concentrations and depths described herein). Relatively high elevated temperatures are generally useful or preferred to react the fluorine source vapor with the yttrium oxide to convert the yttrium oxide to a high concentration of yttrium fluoride (YF3) instead of yttrium oxide fluoride (YOF). Exemplary temperatures for the fluoro-annealing step can be at least 300°C or 350°C, or higher, for example in the range of 300°C to 500°C, for example 350°C or 400°C to 425°C or 450°C, to produce a high concentration of YF3 at the surface portion of the deposited thin film.

[0043] The process chamber can be operated at any useful pressure, with exemplary pressures being about atmospheric pressure (760 Torr), such as from 100 to 1500 Torr, such as from 250 or 500 to 1000 or 1250 Torr. The atmosphere within the process chamber for converting yttrium oxide to yttrium fluoride may include a portion that is air in combination with a molecular fluorine source vapor.

[0044] The amount of time used to form yttrium fluoride by the fluoro-annealing step can be based on factors such as the temperature of the fluoro-annealing step, the type and amount (concentration) of the molecular fluorine source vapor in the process chamber, the thickness and composition of the deposited yttrium oxide thin film, and the desired thickness of the yttrium fluoride portion formed from the deposited yttrium oxide thin film. Examples of useful or preferred amounts of time can range from 1 to 48 hours, such as 2 to 24 hours, or 3 to 12 hours. A useful period of time for performing the fluoro-annealing step can be a period of time that produces a yttrium fluoride portion (of the deposited thin film) having a useful or preferred thickness. By continuously exposing the deposited yttrium oxide thin film to the molecular fluorine source vapor during the fluoro-annealing step, the thickness increases over time. After a certain period of time, such as 12, 18, or 24 hours, the thickness of the yttrium fluoride portion of the deposited thin film may no longer increase substantially.

[0045] The described deposited thin films formed by converting the yttrium oxide of the deposited yttrium oxide thin film to yttrium fluoride will have a composition that includes yttrium, fluorine, oxygen, and possibly small amounts of carbon (e.g., less than 4 or 5 atomic percent carbon), e.g., a yttrium fluoride thin film may contain yttrium fluoride (YF3), latent amounts of yttrium oxide fluoride (YOF), and possibly yttrium oxide (YO3). These different materials may be present in different portions of the thickness (depth) of the deposited thin film in amounts (concentrations) that vary based on the thickness position of the deposited material, i.e., varying with respect to the depth (thickness) of the yttrium fluoride thin film (i.e., non-uniform amounts or concentrations).

[0046] As used herein, the terms "yttrium fluoride thin film" and "yttrium fluoride film" refer to a film or coating produced on a substrate by depositing a layer of yttrium oxide material on the substrate and then converting at least a portion of the deposited yttrium oxide to yttrium fluoride. These processes do not necessarily convert all of the yttrium oxide of the deposited yttrium oxide film to yttrium fluoride. The portion of the film thickness that includes the surface of the film (i.e., the "surface portion") is mostly converted to yttrium fluoride. The middle or lower portion of the film may be converted to yttrium fluoride or yttrium oxide fluoride (YOF) and may contain a higher concentration of oxygen compared to locations closer to the surface. In some cases, the lower portion of the film may be converted to yttrium fluoride, yttrium oxide fluoride, or may remain in the form of yttrium oxide.

[0047] Since the described yttrium fluoride thin film is formed by a fluoro-annealing process, the deposited thin film potentially exhibits non-uniform, e.g., graded, concentrations of one or more atomic components that compose the thin film, particularly fluorine and oxygen. The fluorine concentration in the yttrium fluoride thin film may decrease along the thickness of the film, such that the surface and outer portions ("top" or "surface portions") of the thin film contain a higher concentration of fluorine compared to deeper portions. For example, in some embodiments, the film may have an upper portion substantially made of yttrium fluoride and a lower portion that is yttrium oxide fluoride or even non-yttrium oxide fluoride.

[0048] Different portions of a deposited thin film can be identified and described by X-ray photoelectron spectroscopy or "XPS" techniques based on the variation in composition at different thickness locations of the film. These quantitative spectroscopic techniques allow for compositional analysis of a film or layer of a deposited material at the surface and below the surface of the material, throughout the thickness (depth) of the deposited material. XPS profiling analysis can identify the elemental composition of the deposited material at different locations along the thickness of the material.

[0049] FIG. 1 is an XPS profile of a deposited yttrium oxide thin film deposited by atomic layer deposition as described and subsequently treated to convert the yttrium oxide of the deposited yttrium oxide thin film to yttrium fluoride by a fluoro-annealing process. The "top" portion (or "surface" portion) of the thin film is considered to be the portion of the thin film that includes the surface of the thin film (depth equal to 0) and extends below the surface to a specified thickness (or "depth"). As shown, the surface portion of the tested deposited thin film contains a large amount of yttrium fluoride. The portions of the tested film from the surface (depth 0) to a depth of 50 nanometers and 60 nanometers contain at least 60 atomic percent fluorine and less than 5 percent oxygen, indicating a very high concentration of YF3 and a low concentration of YOF. As shown, the yttrium fluoride thin film is formed on an intermediate layer of aluminum oxide (Al2O3) formed on the surface of a silicon (Si) substrate.

[0050] The yttrium fluoride thin film of the measurement of FIG. 1 can be considered to have a "portion" that can be referred to as "yttrium fluoride", e.g., a "yttrium fluoride portion" that includes a surface portion of the thin film. The yttrium fluoride portion is a portion that includes the thin film surface and extends to a thickness or depth where the composition of the thin film material is substantially yttrium fluoride, e.g., is not substantially yttrium oxide fluoride. As an example, the yttrium fluoride portion can be considered to be a portion of the yttrium fluoride thin film that extends from the surface to a depth where the oxygen concentration in the thin film remains less than 20 atomic percent oxygen. This thickness may be referred to as "t(20%)". Alternatively, the yttrium fluoride portion can be considered to be a portion that extends from the surface to a depth where the oxygen concentration in the thin film remains less than 10 atomic percent oxygen. This thickness may be referred to as "t(10%)".

[0051] Based on a maximum oxygen concentration of 20 atomic percent, an exemplary thickness t(20%) of the described yttrium fluoride portion can be at least 5 or 10 nanometers, such as at least 20 nanometers, from the deposited thin film surface and can have a thickness of up to or more than 50, 75, 100, 125, 150, or 200 nanometers. Stated differently, the yttrium fluoride portion having an oxygen content of less than 20 atomic percent at all thickness locations may extend to a depth of at least 5 nanometers from the surface and up to or more than 10, 20, 50, 75, 100, 125, 150, or 200 nanometers below the surface.

[0052] Based on a maximum oxygen concentration of 10 atomic percent, exemplary thicknesses t(10%) of the described yttrium fluoride portions can be at least 5, 10, or at least 20 nanometers from the deposited thin film surface, and can have thicknesses of up to 50, 75, or 100 nanometers or more. Stated differently, yttrium fluoride portions having an oxygen content of less than 10 atomic percent at all thickness locations may extend to a depth of at least 5 nanometers from the surface, and up to 10, 20, 50, 75, or 100 nanometers or more below the surface.

[0053] As shown in Figure 1, an exemplary yttrium fluoride thin film may include an yttrium oxide fluoride (YOF) portion, for example, at the bottom of the film away from the surface and adjacent to a substrate or intermediate layer. Also, as shown, this may produce a gradual transition from an intermediate (buffer) metal oxide layer (e.g., alumina, zirconia, titania, etc., and combinations thereof) to YOF and then to YF3, rather than a direct transition from the metal oxide layer to YF3. When the yttrium fluoride thin film includes a YOF portion, for example, adjacent to a substrate or intermediate layer, the thickness of the YOF portion may be controlled based on the thickness of the initially deposited YO3 thin film and the conditions of the fluoro-annealing step (temperature, exposure time, etc.), which may be controlled.

[0054] The films of the present invention can also be analyzed by X-ray diffraction to show that the yttrium fluoride portion of the film contains a substantial or high concentration of crystalline YF3, as opposed to other possible stoichiometric combinations of Y, F, and O. X-ray diffraction (XRD) is a known analytical technique for evaluating the atomic and molecular structure of materials, including materials of deposited films. For example, X-ray diffraction is useful for evaluating the structure and stoichiometric characteristics of deposited films of the type described herein, for example, prepared by atomic layer deposition.

[0055] 2 shows XRD data for an exemplary yttrium fluoride film herein. The data shows that the film contains a substantial concentration of (poly)crystalline YF3, as evidenced by diffraction peaks consistent with the expected YF3 signature. To the extent that the film contains an amount of oxygen, the XRD data shows that the film contains a mixture of stoichiometric materials including primarily YF3 in combination with smaller amounts of YOF.

[0056] According to a useful or preferred method, the deposited thin film, and the coated substrate, the substrate to which the deposited thin film may be applied, may include an intermediate layer disposed on the substrate between the substrate and the deposited thin film described. As a step of the described method, a thin film of yttrium oxide may be deposited on the substrate. The thin film of yttrium oxide is then converted to yttrium fluoride by annealing at high temperature in the presence of fluorine, converting at least a substantial portion of the yttrium oxide to yttrium fluoride. The high temperatures used in the fluoro-annealing step may cause physical damage, such as cracks, to the deposited thin film of yttrium oxide.

[0057] In a preferred method, an intermediate layer (e.g., a "buffer layer") may be disposed on the substrate surface between the substrate surface and the yttrium oxide layer to prevent physical damage to the yttrium oxide thin film that may be caused by thermal stresses generated during the fluoro-annealing step. The intermediate layer may be effective to allow the yttrium oxide layer to be processed by the fluoro-annealing step at high temperatures without causing the yttrium oxide layer to crack due to stresses resulting from the high processing temperatures of the fluoro-annealing step. The intermediate layer may have physical properties, such as a coefficient of thermal expansion, that reduce the severity or effect of thermal stresses experienced by the deposited yttrium oxide thin film when the deposited yttrium oxide thin film is processed by the fluoro-annealing step, e.g., at temperatures above 300°C.

[0058] The intermediate layer may be any layer effective to reduce or prevent undesirable physical effects of thermal stress experienced by the deposited yttrium oxide thin film, preferably to prevent cracks or other physical damage to the deposited yttrium oxide thin film from occurring during the fluoro-annealing process. The composition, thickness, and method of preparing the intermediate layer may be any useful for preparing an effective intermediate layer. Exemplary intermediate layers may be made of ceramic materials such as metal oxides, e.g., aluminum oxide, titanium oxide, zirconium oxide, and the like. Exemplary thicknesses may range from 25 to 300 nanometers, e.g., 50 to 200 or 250 nanometers. Exemplary intermediate layers may be applied to the substrate surface by any technique effective to enable the function described for the intermediate layer to prevent physical damage to the deposited yttrium oxide thin film during the fluoro-annealing process. Certain exemplary techniques include chemical vapor deposition, physical vapor deposition, and atomic layer deposition techniques.

[0059] Referring to Figure 3, an example of useful steps of the described method and the described exemplary deposited thin film is shown. According to the method 10, a substrate 20 is provided and in step (i) an intermediate layer 22 is applied to a surface of the substrate 20. In step (ii), a yttrium oxide thin film 24(a) is applied to a surface of the intermediate layer 22. In step (iii), the substrate 20 with the intermediate layer 22 and the deposited yttrium oxide thin film 24(a) is subjected to a fluoro-annealing step that converts at least a portion of the yttrium oxide of the yttrium oxide thin film 24(a) to yttrium fluoride to produce a yttrium fluoride thin film 24(b).

[0060] 4 illustrates the substrate 20, the intermediate layer 22, and the yttrium fluoride thin film 24(b), with additional details regarding the composition of the yttrium fluoride thin film 24(b). As shown, the yttrium fluoride thin film 24(b) has a thickness (t1) between a lower surface 32 (adjacent an upper surface of the intermediate layer 22) and an upper surface 30. Thickness t1 is also the thickness of the deposited yttrium oxide thin film 24(a) when deposited on the intermediate layer 22.

[0061] Transition region 28, represented by a dashed line, indicates a lower boundary of yttrium fluoride portion 34 having a thickness t2 that extends between surface 30 and transition region 28. Yttrium fluoride portion 34 contains a majority of yttrium fluoride (YF3) and a minor amount of oxygen, as described herein.

[0062] The thickness t2 of the yttrium fluoride portion 34 can be defined as described, for example, by defining the transition 28 as being at a depth (thickness) below the surface 30 where the oxygen concentration in the film first reaches 20 percent (atoms), or alternatively, at a location below the surface 30 where the oxygen concentration in the film first reaches 10 percent. In some embodiments, the thickness of the yttrium fluoride portion can be in the range of 10 nanometers to 200 nanometers, 10 nanometers to 175 nanometers, 10 nanometers to 150 nanometers, 10 nanometers to 125 nanometers, 10 nanometers to 100 nanometers, or any range therebetween.

[0063] 3 may have an oxygen concentration ([O]2) of 20 (or 10) atomic percent at the thickness of transition 28. The oxygen concentration at the thickness above transition 28 is less than 20 (or less than 10) and drops gradually (regularly or consistently, if not linearly) to essentially zero ([O]1) at surface 30. The oxygen concentration at the thickness below transition 28 between transition 28 and lower surface 32 is greater than 20 atomic percent (or greater than 10 atomic percent).

[0064] The described yttrium fluoride thin films, including at least a portion containing a high concentration of yttrium fluoride (YF3) and a low concentration of oxygen, can be effective as protective coatings that are chemically resistant to various process materials, particularly (but not limited to) acids and plasmas that may be present in various types of process chambers during operation to perform the manufacturing processes described herein, certain exemplary processes being known or developed in the future.

[0065] Yttrium fluoride has a substantially higher concentration of fluorine compared to previously deposited thin films made from yttrium oxide or yttrium oxide fluoride, and therefore the level of chemical resistance achieved by the yttrium fluoride thin films described herein can be significantly more useful or relatively improved compared to the levels of chemical resistance achieved by previous protective materials.

[0066] Useful and preferred yttrium fluoride thin films can also be heat resistant for extended periods of time, including during use at high temperatures (e.g., in the range of 350-500° C.) in semiconductor processing tools. More generally, useful or preferred yttrium fluoride thin films can resist decomposition at temperatures up to or exceeding 200, 300, 400, 450, or 500° C. for extended periods of time.

[0067] An apparatus, device, or article comprising a yttrium fluoride thin film as a protective coating may comprise a substrate comprising a yttrium fluoride thin film formed on a surface of the substrate, optionally with an intermediate layer disposed between the substrate and the yttrium fluoride thin film. Advantageously, the yttrium fluoride thin film can be prepared using two specific process steps, each of which includes vapor deposition, i.e., atomic layer deposition of yttrium oxide and fluoro-annealing of the deposited yttrium oxide thin film, so that the resulting yttrium fluoride thin film can be effectively and uniformly applied to substrate surfaces that are highly three-dimensional or have high aspect ratios. Useful yttrium fluoride thin films can be applied to three-dimensional surfaces that include channels, grooves, or openings, such as structures with relatively high aspect ratios, for example, aspect ratios of 10:1, 20:1, 50:1, up to 100:1 or more. In some embodiments, the three-dimensional features on the substrate are selected from threaded screws, threaded nuts, porous membranes, filters, three-dimensional networks, holes, and channels.

[0068] Examples of substrates onto which the described protective yttrium fluoride coatings can be applied include items such as various components of process chambers used to prepare semiconductor materials ("process chamber components"), microelectronic devices, etc. Being resistant to process materials such as acids and plasmas, yttrium fluoride thin films can be used to protect process chamber components in the presence of these and other process materials during operation.

[0069] Preferred protective coatings can be prepared to contain low levels of defects, such as cracks, crevices, pinholes, and other physical defects. Defects, such as pinholes, cracks, and crevices, can be identified by visual inspection, optionally under magnification using an optical microscope or a scanning electron microscope, or other suitable inspection methods. Preferred coatings can also be applied to exhibit a high level of coating thickness uniformity across the surface of the coating, especially when compared to coatings applied by other methods, such as physical vapor deposition. For example, a high level of uniformity can refer to a coating that is less than 2 microns thick over an area of ​​1, 5, or 10 square centimeters, and does not vary in thickness by more than 20, 10, or 5 percent over that area.

[0070] The described protective coatings can be usefully formed on any surface or substrate to which yttrium fluoride thin films can be effectively applied. In certain embodiments, the substrate may be made of a vacuum-compatible substrate material or may be in the form of a component of a process chamber used to process substrates, materials, or devices by the use of one or more different process materials that are highly reactive, corrosive, or may violently degrade or react with other materials, including the internal components of the process chamber. In this regard, the described yttrium fluoride thin films can be advantageously applied to substrates, referred to herein as "vacuum-compatible substrates," and formed to function as components ("process components") of process chambers used to process microelectronic devices, semiconductor devices and devices, their precursors, and the like, by treatment with process materials such as plasma.

[0071] The process chamber is useful for containing highly corrosive or reactive process materials, which may be in the form of liquids, gases, or plasmas, used to treat microelectronic or semiconductor device substrates, for example, during the manufacturing process of microelectronic or semiconductor devices. Specific examples of reactive process materials include bromine plasmas, chlorine plasmas, and fluorine plasmas, such as plasmas derived from NF3, Cl2, CHF3, CH2F2, SF or HBr.

[0072] The process chamber must include process chamber components and surfaces useful for transporting, holding, securing, supporting, or moving the workpiece in, out of, and within the process chamber without being unduly degraded by the process materials present in the process chamber. The process chamber must also include a system of structure effective for flowing, delivering, and removing reactive process materials (e.g., plasma) into and out of the process chamber.

[0073] Examples of process chamber components include articles of any shape that includes a flat, planar, essentially two-dimensional surface, but also articles with more complex shapes. Advantageously, the method and thin film can be used with substrates that have physical shapes or forms that are three-dimensional forms, including features that are considered to have high aspect ratios, such as openings, apertures, channels, tunnels, threaded screws, threaded nuts, porous membranes, filters, three-dimensional networks, holes, channels, forms that include extended surfaces, etc. More specific exemplary structures include flow heads (showerheads), shields, trays, supports, nozzles, valves, conduits, stages for handling or holding substrates, wafer handling fixtures, chamber liners, ceramic wafer carriers, wafer holders, susceptors, spindles, chucks, rings, baffles, and various types of fasteners (screws, nuts, bolts, clamps, rivets, etc.).

[0074] The described atomic layer deposition and fluoro-annealing techniques are effective gas phase deposition techniques for providing uniform, high quality deposited thin films on three-dimensional surfaces, including surfaces having aspect ratios of at least 10:1, 20:1, 50:1, 100:1, or more.

[0075] The substrate of the process component on which the yttrium fluoride thin film can be formed can be made from a variety of different solid materials, including materials that are sometimes referred to as "vacuum compatible" substrate materials. In general, examples can include ceramic materials, metals, and metal alloys, which can be coated with a protective coating and used in the process chamber. Examples of ceramic materials that can be useful as vacuum compatible substrates include alumina, silicon carbide, silicon, silicon oxide, and aluminum nitride. Examples of metals and metal alloys include nickel, nickel alloys, stainless steel, and aluminum. Vacuum compatible substrates can also be quartz, sapphire, silica, fused silica, fused quartz, silicon, anodized aluminum, zirconium oxide, glass, and plastics such as certain plastics used in the semiconductor industry, such as polyetheretherketone (PEEK) and polyimide. In some embodiments, the substrate can be a wall of a plasma etch chamber, a wafer susceptor, a chuck, a showerhead, a liner, a ring, a nozzle, a baffle, a fastener, a wafer support, a wafer transfer structure, or a part or component of any one of these.

[0076] Although the present specification often refers to process chambers and process chamber components (e.g., etch chamber components) as useful substrates for the described protective coatings, the described yttrium fluoride thin films are not limited to use with these items. As described herein, various other ceramic, mineral, metal, and metal alloy articles and substrates that would benefit from a protective coating having a high level of resistance to highly reactive chemical materials can also be treated to deposit a yttrium fluoride thin film on their surface.

Claims

1. A substrate; A yttrium fluoride film coated on a substrate, comprising: yttrium, Fluorine, oxygen, surface, Thickness, and a yttrium fluoride portion extending from the surface through a portion of the thickness having an oxygen concentration of less than 20 percent (atomic); A yttrium fluoride film containing Including, The concentrations of fluorine and oxygen in the yttrium fluoride film vary gradually with thickness, The yttrium fluoride film further comprises a surface portion having a thickness of at least 50 nanometers, the surface portion comprising: less than 15 percent (atomic) oxygen through the entire thickness of the surface portion as measured by X-ray photoelectron spectroscopy; and At least 50 percent (atomic) fluorine throughout the thickness of the surface portion as measured by X-ray photoelectron spectroscopy. A coated substrate comprising:

2. The coated substrate of claim 1 , wherein the yttrium fluoride portion has a thickness in the range of 10 to 150 nanometers.

3. The coated substrate of claim 1 , wherein the substrate comprises a three-dimensional structure having an aspect ratio of at least 10:

1.

4. The coated substrate of claim 1 further comprising an intermediate layer disposed between the substrate and the yttrium fluoride thin film.

5. The coated substrate of claim 1 , wherein the substrate is a process component of a microelectronic device or semiconductor manufacturing system.

6. 10. The coated substrate of claim 1, wherein the substrate comprises a wall of a plasma etch chamber, a wafer susceptor, a chuck, a showerhead, a liner, a ring, a nozzle, a baffle, a fastener, a wafer support, a wafer transport structure, or a portion or component of any one of these.

7. 10. The coated substrate of claim 1, wherein the substrate comprises a three-dimensional feature selected from a threaded screw, a threaded nut, a porous membrane, a filter, a three-dimensional network, a hole, and a channel.

8. 1. A method for preparing a yttrium fluoride film comprising the steps of: depositing a yttrium oxide film on the surface by atomic layer deposition; exposing the yttrium oxide film to molecular fluorine source vapor and elevated temperature to convert the yttrium oxide of the yttrium oxide film to yttrium fluoride; Including, The high temperature is a temperature exceeding 300° C. The concentrations of fluorine and oxygen in the yttrium fluoride film vary gradually with the thickness of the yttrium fluoride film, The yttrium fluoride film includes a surface portion having a thickness of at least 50 nanometers, the surface portion comprising: less than 15 percent (atomic) oxygen through the entire thickness of the surface portion as measured by X-ray photoelectron spectroscopy; and At least 50 percent (atomic) fluorine throughout the thickness of the surface portion as measured by X-ray photoelectron spectroscopy. A method comprising:

9. 9. The method of claim 8, wherein exposing the yttrium oxide film to fluorine and elevated temperature forms a yttrium fluoride portion of the yttrium oxide film, the yttrium fluoride portion having a thickness between the surface and a subsurface location where the film contains 20 atomic percent oxygen.

10. The method of claim 8 , wherein the surface comprises an intermediate layer, and the method comprises depositing a thin film of yttrium oxide on the intermediate layer.

11. 1. A method for preparing a yttrium fluoride film comprising the steps of: depositing a yttrium oxide film on the surface by atomic layer deposition; exposing the yttrium oxide film to molecular fluorine source vapor and elevated temperature to convert the yttrium oxide of the yttrium oxide film to yttrium fluoride; Including, The high temperature is a temperature exceeding 300° C. The concentrations of fluorine and oxygen in the yttrium fluoride film vary gradually with the thickness of the yttrium fluoride film, The method does not involve plasma.

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