Yttrium oxyfluoride sintered body and semiconductor manufacturing equipment component

Abstract

To provide a sintered body of yttrium oxyfluoride, which is excellent in corrosion resistance, dense, and excellent in mechanical characteristics.SOLUTION: The sintered body of yttrium oxyfluoride comprising Y5O4F7 and YF3 as its main components, comprises a center part and a surface layer surrounding the center part and containing a smaller amount of YF3 relative to the center part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sintered body of yttrium oxyfluoride and a member for semiconductor manufacturing equipment. [Background technology]

[0002] Fluorine-based corrosive gases and chlorine-based corrosive gases and plasmas using these gases are used in various steps in the manufacture of semiconductors, particularly in the steps of dry etching, plasma etching and cleaning.

[0003] When these corrosive gases and plasmas are used, the components of the semiconductor manufacturing equipment can corrode, and fine particles that peel off from the surfaces of the components can adhere to the surface of the semiconductor, easily causing product defects. For this reason, the components of the semiconductor manufacturing equipment must use ceramics, which have high corrosion resistance to halogen-based plasmas, as bulk materials.

[0004] As such bulk materials, aluminum oxide, yttrium oxide, aluminum-yttrium composite oxide, and yttrium fluoride have been proposed (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-136877 A [Patent Document 2] JP 2013-144622 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, recently, oxygen plasma has also been used to oxidize and remove resist, and there is a demand for sintered bodies with better corrosion resistance against various corrosive gases and plasmas. However, the above-mentioned materials do not have sufficient corrosion resistance, and there is a problem that a sintered body that has excellent corrosion resistance against various corrosive gases and plasmas, as well as being dense and having excellent mechanical properties has not yet been obtained.

[0007] In view of the above problems, an object of the present invention is to provide a sintered body of yttrium oxyfluoride that is excellent in corrosion resistance, dense, and also excellent in mechanical properties. [Means for solving the problem]

[0008] The yttrium oxyfluoride sintered body of the present invention, which solves the above-mentioned problems, is mainly composed of Y5O4F7 and YF3, and has a central portion and a surface layer that exists around the central portion and has a lower YF3 content than the central portion. The yttrium oxyfluoride sintered body of the present invention is mainly composed of Y5O4F7 and YF3, and therefore has high corrosion resistance against halogens and oxygen plasma. In addition, it is a sintered body containing two phases of Y5O4F7 and YF3, and the thermal expansion coefficient of each is 6×10 for Y5O4F7. -6 / K, YF3 is 14 x 10 -6 / K, the thermal expansion coefficient is higher in regions with a high YF3 content than in regions with a low YF3 content. As a result, in the surface layer with a low YF3 content, compressive stress is applied due to interaction with the center, resulting in a dense and strong surface, and a sintered body of yttrium oxyfluoride with excellent mechanical properties can be obtained.

[0009] In the yttrium oxyfluoride sintered body of the present invention, the content of YF3 in the central portion is preferably 5 to 40 wt %. When the YF3 content in the center is 5 wt% or more, it is possible to easily apply strong compressive stress to the surface layer through interaction.When the YF3 content in the center is 40 wt% or less, the basic material properties of yttrium oxyfluoride can be maintained, and the material can be suitably used as a sintered body of yttrium oxyfluoride.

[0010] In the yttrium oxyfluoride sintered body of the present invention, the content of YF3 in the surface layer portion is preferably 1 / 10 or less of the content of YF3 in the central portion. When the YF3 content in the surface layer is 1 / 10 or less of the YF3 content in the center portion, the difference in thermal expansion coefficient can be increased, so that a large compressive stress can be applied to the surface of the sintered body. Also, since the YF3 content in the surface layer is low, high corrosion resistance against various corrosive gases and plasmas can be obtained.

[0011] In the yttrium oxyfluoride sintered body of the present invention, the surface layer portion preferably has a thickness of 2 to 200 μm. When the thickness of the surface layer is 2 μm or more, distortion due to thermal expansion mismatch between the center and surface layer is unlikely to act in the thickness direction, making it possible to provide a sintered body that is unlikely to peel off. When the thickness of the surface layer is 200 μm or less, the cross-sectional area ratio subject to thermal expansion mismatch between the central portion and the surface layer can be reduced, making it easier to obtain a large compressive stress.

[0012] In the yttrium oxyfluoride sintered body of the present invention, the surface layer portion preferably has a smaller porosity than the central portion. Since the porosity of the surface layer is smaller than that of the center portion, the surface layer is dense, and therefore it is possible to obtain a sintered body of yttrium oxyfluoride having high corrosion resistance against various corrosive gases and plasmas and excellent mechanical properties. On the other hand, since the porosity of the center portion is relatively larger than that of the surface layer portion, the stress caused by the difference in thermal expansion coefficient between the center portion and the surface layer portion is alleviated, and the stress applied to the boundary region between the center portion and the surface layer portion is suppressed, and compressive stress can be effectively applied to the surface layer portion.

[0013] In the yttrium oxyfluoride sintered body of the present invention, the porosity of the central portion is preferably 1 to 4%. When the porosity of the central portion is within the above range, compressive stress can be effectively applied to the surface layer portion.

[0014] Moreover, a semiconductor manufacturing equipment member of the present invention comprises the above-mentioned yttrium oxyfluoride sintered body. The yttrium oxyfluoride sintered body is mainly composed of Y5O4F7 and YF3, and therefore has high corrosion resistance against halogens and oxygen plasma. In addition, it is a sintered body containing two phases of Y5O4F7 and YF3, and the thermal expansion coefficients of Y5O4F7 and YF3 are 6×10 -6 / K, YF3 is 14 x 10 -6 / K, the thermal expansion coefficient is higher in the region with a high YF3 content than in the region with a low YF3 content. Therefore, in the surface layer portion with a low YF3 content, compressive stress is applied during cooling after sintering due to interaction with the center, resulting in a dense and strong surface, and a sintered body of yttrium oxyfluoride with excellent mechanical properties can be obtained. By providing such a sintered body, it is possible to provide a semiconductor manufacturing equipment member with a dense and strong surface and excellent mechanical properties. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view that typically illustrates the cross-sectional structure of a sintered body of yttrium oxyfluoride. [Diagram 2] 2A, 2B, 2C, 2D, 2E, 2F, and 2G are process diagrams that typically show an example of a manufacturing process for a sintered body of yttrium oxyfluoride. [Diagram 3] FIG. 3 is a chart showing the results of X-ray diffraction of the sintered body of yttrium oxyfluoride according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (Yttrium oxyfluoride sintered body) The yttrium oxyfluoride sintered body of the present invention is a sintered body of yttrium oxyfluoride characterized in that it contains Y5O4F7 and YF3 as main components, and has a central portion and a surface layer that exists around the central portion and has a lower YF3 content than the central portion. Hereinafter, in this specification, the sintered body of yttrium oxyfluoride may be simply referred to as a sintered body.

[0017] FIG. 1 is a cross-sectional view that typically illustrates the cross-sectional structure of a sintered body of yttrium oxyfluoride. The yttrium oxyfluoride sintered body 1 shown in FIG.

[0018] The yttrium oxyfluoride sintered body is composed mainly of Y5O4F7 and YF3. The term "composed mainly of Y5O4F7 and YF3" means that, as long as there is no effect on the interaction of the thermal expansion coefficients of Y5O4F7 and YF3, the components constituting the sintered body other than Y5O4F7 and YF3 are preferably less than 15 wt%, and more preferably less than 5 wt%. In a sintered body of yttrium oxyfluoride, since the main components are Y5O4F7 and YF3, it has strong corrosion resistance against halogens and oxygen plasma.

[0019] The surface layer portion 20 is a region in which the content of YF3 is less than that in the central portion. Since the YF3 content changes suddenly at the boundary between the surface layer 20 and the central portion 10, when the YF3 content changes suddenly with respect to the depth from the surface, that depth is taken as the boundary between the central portion and the surface layer, whereas when the YF3 content changes broadly, the inflection point in the content curve is taken as the boundary between the central portion and the surface layer.

[0020] The sintered body of yttrium oxyfluoride is a sintered body containing two phases, Y5O4F7 and YF3, and the thermal expansion coefficient of each is 6×10 for Y5O4F7. -6 / K, YF3 is 14 x 10 -6 / K, the thermal expansion coefficient is higher in areas with a high YF3 content than in areas with a low YF3 content. Therefore, in the surface layer with a low YF3 content, compressive stress is applied due to interaction with the center, resulting in a dense and strong surface. As a result, it is possible to obtain a sintered body of yttrium oxyfluoride with excellent mechanical properties.

[0021] The YF3 content in the surface layer and the center can be determined by quantitative analysis using EPMA. That is, the surface layer (point B in Fig. 1) and the center (point A in Fig. 1) of the sintered body containing two phases of Y5O4F7 and YF3 are analyzed using EPMA, and the YF3 content can be determined from the oxygen content analysis.

[0022] The YF3 content in the surface layer is preferably 1 / 10 or less of the YF3 content in the central portion. When the YF3 content in the surface layer portion is 1 / 10 or less of the YF3 content in the central portion, the difference in thermal expansion coefficient can be made large, so that a large compressive stress can be applied to the surface of the sintered body.

[0023] The content of YF3 in the central portion is preferably 5 to 40 wt %. When the YF3 content in the center is 5 wt% or more, it is possible to easily apply strong compressive stress to the surface layer through interaction.When the YF3 content in the center is 40 wt% or less, the basic material properties of yttrium oxyfluoride can be maintained, and the material can be suitably used as a sintered body of yttrium oxyfluoride.

[0024] The thickness of the surface layer is preferably 2 to 200 μm. When the thickness of the surface layer is 2 μm or more, distortion due to thermal expansion mismatch between the center and surface layer is unlikely to act in the thickness direction, making it possible to provide a sintered body that is unlikely to peel off. When the thickness of the surface layer is 200 μm or less, the cross-sectional area ratio subject to thermal expansion mismatch between the central portion and the surface layer can be reduced, making it easier to obtain a large compressive stress.

[0025] The surface layer preferably has a smaller porosity than the central portion. Since the porosity of the surface layer is smaller than that of the center portion, the surface layer is dense, and therefore it is possible to obtain a sintered body of yttrium oxyfluoride having high corrosion resistance against various corrosive gases and plasmas and excellent mechanical properties. On the other hand, since the porosity of the center portion is relatively larger than that of the surface layer portion, the stress caused by the difference in thermal expansion coefficient between the center portion and the surface layer portion is alleviated, and the stress applied to the boundary region between the center portion and the surface layer portion is suppressed, and compressive stress can be effectively applied to the surface layer portion.

[0026] The porosity of the central portion is preferably 1 to 4%. When the porosity of the central portion is within the above range, compressive stress can be effectively applied to the surface layer portion. In addition, the porosity of the surface layer is preferably smaller than the porosity of the central portion. Since the porosity of the surface layer is smaller than that of the center portion, the surface layer becomes dense, and therefore it is possible to obtain a sintered body of yttrium oxyfluoride having high corrosion resistance against various corrosive gases and plasmas and excellent mechanical properties.

[0027] The porosity of the central portion and the surface portion can be determined from the cross-sectional area ratio of the pore portions in the cross section of the yttrium oxyfluoride sintered body, and can actually be obtained by calculating the area of ​​the pore portions in a scanning electron microscope photograph taken at 1000x magnification.

[0028] (Method for producing sintered body of yttrium oxyfluoride) The yttrium oxyfluoride sintered body of the present invention can be produced by the following production method.

[0029] The yttrium oxyfluoride sintered body of the present invention can be produced, for example, by using raw materials having different composition ratios as raw materials constituting the central portion and the surface layer portion, respectively.

[0030] As the raw material for the center portion, a powder of the raw material composition for the center portion is used, and as the raw material for the surface layer portion, a powder of the raw material composition for the surface layer portion is used. The powder of the raw material composition for the core portion and the powder of the raw material composition for the surface layer portion are mixed so that Y5O4F7 and YF3 are the main components in the sintered body after sintering. As the raw materials, Y5O4F7 and YF3 may be used in combination, YOF and YF3 may be used in combination, or Y5O4F7, YOF and YF3 may be used in combination. By combining the above-mentioned raw materials, it is possible to obtain yttrium oxyfluoride containing Y5O4F7 and YF3 as the main components.

[0031] In the powder of the raw material composition for the core, when Y5O4F7 and YF3 are combined, the molar ratio of Y5O4F7 to YF3 is preferably Y5O4F7:YF3=10:2 to 30. When YOF and YF3 are combined, the molar ratio of YOF to YF3 is preferably YOF:YF3=10:5 to 40.

[0032] The powder of the raw material composition for the surface layer portion is adjusted so that the content (content ratio) of YF3 in the surface layer portion after sintering is less than the content (content ratio) of YF3 in the center portion after sintering. In particular, it is preferable that the powder of the raw material composition for the surface layer portion does not contain YF3. In the powder of the raw material composition for the surface layer portion, when Y5O4F7 and YF3 are combined, the molar ratio of Y5O4F7 to YF3 is preferably Y5O4F7:YF3=10:0-1. When YOF and YF3 are combined, the molar ratio of YOF to YF3 is preferably YOF:YF3=10:2-4. Of Y5O4F7, YOF and YF3, the powder of the raw material composition for the surface layer portion may contain only Y5O4F7.

[0033] In addition to the above-mentioned fluorides such as Y5O4F7, YOF, and YF3, additives such as organic binders, lubricants, dispersion media, and molding aids may be appropriately added to the raw material compositions for the core and surface layers. The organic binder is not particularly limited, and examples thereof include polyacrylonitrile (PAN), acrylic resin, phenol resin, epoxy resin, imide resin, and furan resin. The lubricant is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether. The dispersion medium is not particularly limited, and examples thereof include water, organic solvents such as benzene, and alcohols such as methanol. The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol, and the like.

[0034] In order to prevent segregation of the raw materials used and to improve ease of handling, it is preferable to use the raw material composition for the core portion and the raw material composition for the surface portion as powders by dispersing raw material particles in a dispersion medium and granulating the dispersed raw material. The granulation method is not particularly limited, and for example, spray drying, rolling granulation, etc. can be used.

[0035] The particle size (average particle size) of the powder obtained by granulation is preferably, for example, 10 to 200 μm.

[0036] 2A, 2B, 2C, 2D, 2E, 2F, and 2G are process diagrams that typically show an example of a manufacturing process for a sintered body of yttrium oxyfluoride. Below, the process for producing a sintered body of yttrium oxyfluoride using a powder of a raw material composition for the core portion and a powder of a raw material composition for the surface layer portion will be described according to this process diagram.

[0037] FIG. 2A shows a powder 100 of the core ingredient composition. 2B, the powder of the raw material composition for the center portion is provisionally molded into a predetermined shape to produce a provisionally molded body for the center portion 110. The method of provisional molding is not particularly limited, but may be embossing molding, CIP molding, or the like.

[0038] FIG. 2C shows a powder 120 of the raw material composition for the surface layer.

[0039] FIG. 2D shows a state in which a powder 120 of raw material composition for the surface layer portion and a temporary molded body 110 for the central portion are placed inside a mold 130 of a predetermined shape. The powder 120 of the raw material composition for the surface layer portion is placed in the mold 130 to a predetermined depth, and the temporary molded body 110 for the center portion is buried in the powder 120 of the raw material composition for the surface layer portion. Then, the powder 120 of the raw material composition for the surface layer portion is added so that the temporary molded body 110 for the center portion is hidden, and the powder 120 of the raw material composition for the surface layer portion and the temporary molded body 110 for the center portion are arranged as shown in FIG. 2D.

[0040] As shown in FIG. 2E, a lid 140 corresponding to the shape of the mold 130 is placed, and the powder 120 of raw material composition for the surface layer portion and the temporary molded body 110 for the central portion placed in the mold 130 are pressed. After pressing, the mold 130 and the lid 140 are removed to obtain a molded body 150 having a layer of powder 120 of raw material composition for the surface layer provided around the provisional molded body for the center 110, as shown in FIG. 2F. The molding pressure at this time is preferably, for example, 50 to 500 MPa. During this process, the green body should be handled gently so that the powder 120 of raw material composition for the surface layer portion and the provisional green body 110 for the central portion are not mixed together.

[0041] The obtained molded body is degreased, sintered to bond the particles together, and then sintered to obtain a sintered body of yttrium oxyfluoride of the present invention (see FIG. 2G). The sintering temperature and atmosphere are not particularly limited, but the atmosphere is preferably an inert atmosphere such as argon, and the sintering temperature is preferably 800 to 1100°C. The pressure during sintering may be normal pressure, or may be hot isostatic pressing (HIP) in which particles are sintered while pressing a molded body, or spark plasma sintering (SPS) in which particles are sintered by mechanical pressure and pulse current heating, etc. When pressing by HIP or the like, the pressure is preferably 10 to 200 MPa, for example.

[0042] As described above, a surface layer having a constant thickness can be formed by fabricating a provisionally molded body for the central portion, embedding it in a mold with powder of the raw material composition for the surface layer portion, and molding it again. Alternatively, instead of preparing a provisional molded body for the center portion, a powder of the raw material composition for the center portion and a powder of the raw material composition for the surface portion may be filled separately, and molded so as not to mix the powders together to obtain a molded body molded into a predetermined shape.

[0043] FIG. 3 is a chart showing the results of X-ray diffraction of the sintered body of yttrium oxyfluoride according to the present invention. This is a chart of a sintered body of yttrium oxyfluoride obtained at a debinding temperature of 600°C, a sintering temperature of 950°C or 1000°C, and a sintering time of 2 hours, and shows a comparison between the chart of the surface layer and the chart of the center. In both cases, the peak of the cubic crystal of Y5O4F7 can be confirmed at 2θ = 28 to 29°. The peak of YF3 appears at 2θ = 24 to 26°, but although the presence of this peak can be confirmed in the center, it is only observed to the extent that it is difficult to judge whether it is even present in the surface layer. That is, it is found that the YF3 content is lower in the surface layer portion than in the central portion of the sintered body.

[0044] A semiconductor manufacturing equipment member of the present invention is characterized by comprising the above-mentioned yttrium oxyfluoride sintered body. The yttrium oxyfluoride sintered body is mainly composed of Y5O4F7 and YF3, so it has strong corrosion resistance against halogens and oxygen plasma. In addition, it is a sintered body containing two phases of Y5O4F7 and YF3, and the thermal expansion coefficient of Y5O4F7 is 6×10 -6 / K, YF3 is 14 x 10 -6 / K, the thermal expansion coefficient is higher in the region with a high YF3 content than in the region with a low YF3 content. Therefore, in the surface layer portion with a low YF3 content, compressive stress is applied due to interaction with the center, resulting in a dense and strong surface, and a sintered body of yttrium oxyfluoride with excellent mechanical properties can be obtained. By providing such a sintered body, it is possible to provide a semiconductor manufacturing equipment member with a dense and strong surface and excellent mechanical properties.

[0045] Furthermore, according to the semiconductor manufacturing equipment member of the present invention, a sintered body of yttrium oxyfluoride is used as the semiconductor manufacturing equipment member, and since the main components are Y5O4F7 and YF3, it is resistant to corrosion by halogen-based plasma, has excellent resistance, and can be used for a long period of time.

[0046] Specific examples of the semiconductor manufacturing equipment member of the present invention include, but are not limited to, a stage for mounting a semiconductor member such as a wafer, an electrostatic chuck, a gas supply unit, a coolant supply unit, a transfer arm, a chamber inner wall material, an upper electrode, a shower plate, a focus ring, and an edge plate. [Explanation of symbols]

[0047] 1. Sintered yttrium oxyfluoride 10 Center 20 Surface layer 100 Powder of raw material composition for the core 110 Temporary molded body for central part 120 Powder of raw material composition for surface layer 130 type 140 Lid 150 Molded body

Claims

1. Y ５ O ４ F ７ and Y.F. ３ The main components are The center and The YF ３ and a surface layer portion having a low content of At the boundary between the central portion and the surface portion, the YF 3 concentration changes suddenly, or the YF 3 content curve has an inflection point; The content of YF 3 in the central portion is 5 to 40 wt %, A sintered body of yttrium oxyfluoride, wherein the content of YF 3 in the surface layer portion is 1 / 10 or less of the content of YF 3 in the central portion.

2. The yttrium oxyfluoride sintered body according to claim 1, characterized in that the thickness of the surface layer is 2 to 200 μm.

3. 3. The yttrium oxyfluoride sintered body according to claim 1, wherein the surface layer portion has a smaller porosity than the central portion.

4. The yttrium oxyfluoride sintered body according to any one of claims 1 to 3, characterized in that the porosity of the central portion is 1 to 4%.

5. A semiconductor manufacturing equipment member comprising the yttrium oxyfluoride sintered body according to any one of claims 1 to 4.

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