Sintered bodies and semiconductor manufacturing equipment components

Abstract

To improve plasma resistance of a sintered yttrium oxyfluoride (Y5O4F7).SOLUTION: A sintered compact comprises yttrium oxyfluoride (Y5O4F7), wherein an average particle size of the yttrium oxyfluoride (Y5O4F7) crystals in the sintered compact is 10 μm or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Plasma using a fluorine-based corrosive gas is used in various steps in the manufacture of semiconductors, particularly in the dry etching, plasma etching and cleaning steps.

[0003] When plasma using these corrosive gases is used, the components of semiconductor manufacturing equipment corrode, and fine particles that peel off from the surfaces of the components adhere to the surface of the semiconductor, which can easily cause product defects. Therefore, the components of semiconductor manufacturing equipment must use ceramics that are highly corrosion-resistant to plasma using fluorine-based corrosive gases as their bulk materials.

[0004] As such a bulk material, a sintered body containing yttrium oxyfluoride has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5911036 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although Patent Document 1 describes the corrosion resistance of the YOF sintered body as an yttrium oxyfluoride against plasma, the corrosion resistance of the Y5O4F7 sintered body against plasma has not been studied, and further improvement in corrosion resistance was necessary.

[0007] In view of the above problems, the present invention aims to improve the plasma resistance of a sintered body of yttrium oxyfluoride (Y5O4F7). [Means for solving the problem]

[0008] The sintered body of the present invention for solving the above problems is a sintered body made of yttrium oxyfluoride (Y5O4F7), characterized in that the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals in the sintered body is 10 μm or more. It is believed that plasma corrosion begins at triple junctions formed by yttrium oxyfluoride (Y5O4F7) crystals, and when the average particle size of the crystals is large, the density of triple junctions per unit area decreases, making plasma corrosion less likely to progress. Therefore, by adjusting the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals to 10 μm or more, corrosion resistance to plasma can be improved. In the present invention, it is desirable to adjust the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals to 70 μm or more. Furthermore, it is desirable to adjust the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals to 100 μm or less, because if the average particle size is too large, the fracture toughness value of the sintered body will decrease.

[0009] It is desirable that no peaks due to yttrium fluoride (YF3) crystals are observed in the powder X-ray diffraction chart of the sintered body of the present invention. This is because by growing yttrium oxyfluoride (Y5O4F7) crystals preferentially over yttrium fluoride (YF3) crystals, the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals can be increased.

[0010] Furthermore, in the sintered body of the present invention, the amount of yttrium fluoride (YF3) crystal particles present in the sintered body made of yttrium oxyfluoride (Y5O4F7) is reduced to a level that cannot be confirmed by powder X-ray diffraction, thereby eliminating the opportunity for selective etching by plasma of the yttrium fluoride (YF3) crystal particles and the particle boundaries between the yttrium fluoride (YF3) crystal particles and yttrium oxyfluoride (Y5O4F7). This prevents the generation of voids in the sintered body, thereby improving the corrosion resistance of the sintered body made of yttrium oxyfluoride (Y5O4F7).

[0011] In the sintered body of the present invention, the powder X-ray diffraction chart of the sintered body is preferably measured under the conditions of a powder X-ray diffractometer using CuKα X-rays, an X-ray tube voltage of 40 kV, a current of 20 mA, a scanning range of 2θ=10 to 70°, and a scanning speed of 10° / min, because these are the most standard measurement conditions for powder X-ray diffraction charts.

[0012] In the sintered body of the present invention, it is desirable that only peaks based on yttrium oxyfluoride (Y5O4F7) crystals are confirmed in the powder X-ray diffraction chart of the sintered body. This is because impurity crystal particles other than yttrium oxyfluoride (Y5O4F7), not limited to yttrium fluoride (YF3), form particle boundaries with yttrium oxyfluoride (Y5O4F7), and corrosion by plasma easily progresses from these particle boundaries, forming voids.

[0013] The semiconductor manufacturing equipment member of the present invention comprises the above-mentioned yttrium oxyfluoride (Y5O4F7) sintered body. The sintered body of yttrium oxyfluoride (Y5O4F7) has high corrosion resistance against plasma, and therefore can provide semiconductor manufacturing equipment components with excellent corrosion resistance and impact resistance. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an electron microscope photograph of the surface of the sintered body of yttrium oxyfluoride (Y5O4F7) according to Example 1. [Figure 2] FIG. 2 is an electron microscope photograph of the surface of the yttrium oxyfluoride sintered body (Y5O4F7) according to Test Example 1. [Figure 3] FIG. 3 is a powder X-ray diffraction chart of the sintered body according to Test Example 1. [Figure 4] FIG. 4 is a powder X-ray diffraction chart of the sintered body according to Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] (Sintered body of yttrium oxyfluoride (Y5O4F7)) The sintered body of the present invention is a sintered body made of yttrium oxyfluoride (Y5O4F7), and is characterized in that the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals in the sintered body is 10 μm or more. It is believed that plasma corrosion begins at triple junctions formed by yttrium oxyfluoride (Y5O4F7) crystals, and when the average particle size of the crystals is large, the density of triple junctions per unit area decreases, making it more difficult for plasma corrosion to progress. Therefore, by adjusting the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals to 10 μm or more, corrosion resistance to plasma can be improved. It is also desirable to adjust the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals to 70 μm or more. Furthermore, it is desirable to adjust the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals to 100 μm or less, because if the average particle size is too large, the fracture toughness value of the yttrium oxyfluoride (Y5O4F7) sintered body will decrease.

[0016] Furthermore, in the sintered body of the present invention, it is desirable to reduce the amount of yttrium fluoride (YF3) crystal particles present in the sintered body made of yttrium oxyfluoride (Y5O4F7) to a level that cannot be confirmed by powder X-ray diffraction. This is because by growing yttrium oxyfluoride (Y5O4F7) crystals preferentially over yttrium fluoride (YF3) crystals, the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals can be increased. Furthermore, if yttrium fluoride (YF3) crystal particles are present in a sintered body made of yttrium oxyfluoride (Y5O4F7) to the extent that they can be confirmed by powder X-ray diffraction, the plasma will preferentially etch the yttrium fluoride (YF3) crystal particles and the particle boundaries between the yttrium fluoride (YF3) crystal particles and yttrium oxyfluoride (Y5O4F7), creating voids in the sintered body that can further accelerate the etching; however, the occurrence of such voids can be suppressed by reducing the amount of yttrium fluoride (YF3) crystal particles to the extent that they cannot be confirmed by powder X-ray diffraction.

[0017] In the sintered body of the present invention, the powder X-ray diffraction chart of the sintered body is preferably measured under the conditions of a powder X-ray diffractometer using CuKα X-rays, an X-ray tube voltage of 40 kV, a current of 20 mA, a scanning range of 2θ=10 to 70°, and a scanning speed of 10° / min, because these are the most standard measurement conditions for powder X-ray diffraction charts. "No peaks based on yttrium fluoride (YF3) crystals are observed" means that no peaks are observed at the peak appearance positions (2θ) specified by JCPDS card number 32-1431, which is the diffraction profile of yttrium fluoride (YF3), or even if a peak is observed, the S / N ratio is less than 2, and the peak can be treated as not being present. Furthermore, the powder X-ray diffraction device used can be the most standard device, SmartLab manufactured by Rigaku Corporation.

[0018] In the present invention, it is desirable that only peaks based on yttrium oxyfluoride (Y5O4F7) crystals are confirmed in the powder X-ray diffraction chart of the sintered body. This is because impurity crystal particles other than yttrium oxyfluoride (Y5O4F7), not limited to yttrium fluoride (YF3), form particle boundaries with yttrium oxyfluoride (Y5O4F7), and corrosion from these particle boundaries is likely to progress due to CF4 plasma or O2 plasma, forming voids. "Only peaks based on yttrium oxyfluoride (Y5O4F7) crystals are observed" means that peaks are observed at the peak appearance positions (2θ) specified by JCPDS card number 01-080-1124, which is the diffraction profile of yttrium oxyfluoride (Y5O4F7), and no peaks are observed at other positions (2θ), or even if peaks are observed, the S / N ratio is less than 2, and they can be treated as not existing.

[0019] (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. In the present invention, a sintered body made of Y5O4F7 can be obtained by combining Y2O3 and YF3 as raw materials and sintering them.

[0020] Furthermore, when Y2O3 and YF3 are combined, the molar ratio of Y2O3:YF3 is preferably 100:175 to 200. In a sintered body obtained by sintering this raw material composition, YF3 crystal particles are not generated in the Y5O4F7 matrix, or even if they are generated, they can be suppressed to such an extent that peaks due to the YF3 crystal particles are not observed in a powder X-ray diffraction chart, and the average particle size of the Y5O4F7 crystal particles can be adjusted to 10 μm or more.

[0021] Furthermore, by setting the sintering temperature to a temperature higher than 950°C, the average particle size of the Y5O4F7 crystal particles can be adjusted to 10 μm or more. The sintering temperature is preferably 1000°C or higher. The sintering temperature is preferably 1200°C or lower.

[0022] In addition to the above-mentioned fluorides such as Y2O3, Y5O4F7 and YF3, additives such as organic binders, lubricants, dispersion media and molding aids may be added to the raw material composition as appropriate. 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.

[0023] 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 acids, fatty acid soaps, polyalcohols, and the like.

[0024] The particle size (average particle diameter) of the powder obtained by granulating the raw material composition is preferably, for example, 10 to 200 μm.

[0025] The process for producing a sintered body of yttrium oxyfluoride will be described. The powder of the raw material composition described above is pre-molded into a predetermined shape to produce a pre-molded body. The pre-molding method is not particularly limited, but methods such as embossing and CIP molding can be used.

[0026] The resulting molded body is degreased and fired to bond the particles together and sinter, thereby obtaining the sintered body of yttrium oxyfluoride of the present invention. The firing temperature and atmosphere are not particularly limited, but the atmosphere is preferably an inert atmosphere such as argon, and the firing temperature is preferably above 950°C and 1100°C or less. The pressure during firing may be normal pressure, or alternatively, methods such as hot isostatic pressing (HIP), in which particles are sintered while pressure is applied to the compact, or spark plasma sintering (SPS), in which particles are sintered by mechanical pressure and pulse current heating, may be used.

[0027] The semiconductor manufacturing equipment member of the present invention is characterized by comprising the above-mentioned sintered body of yttrium oxyfluoride (Y5O4F7). The yttrium oxyfluoride sintered body is made of Y5O4F7, and since the average particle size of the yttrium oxyfluoride (Y5O4F7) crystals in the sintered body is 10 μm or more, it has high corrosion resistance to plasma. Therefore, by using the above-mentioned sintered body of yttrium oxyfluoride (Y5O4F7), it is possible to provide a member for a semiconductor manufacturing device used in a plasma atmosphere. Examples of plasma include CF4 plasma and O2 plasma.

[0028] 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. [Example]

[0029] EXAMPLES Hereinafter, examples will be given that more specifically disclose the present invention, but the present invention is not limited to the following examples.

[0030] Example 1 46.2 parts by weight of Y2O3, 53.8 parts by weight of YF3 (molar ratio of Y2O3:YF3=100:179, i.e., the composition after the firing reaction is molar ratio of Y5O4F7:YF3=100:2), 3.0 parts by weight of acrylic resin as an organic binder, and 40 parts by weight of an alcohol-based solvent as a dispersion medium were mixed, and then the mixture was dried at 70°C using a spray dryer and granulated to prepare a granular raw material composition. The particle size of the obtained granular particles was adjusted by cutting (removing) particles with a particle size of 80 μm or more.The alcohol solvent was 86 wt % ethanol and 14 wt % isopropyl alcohol.

[0031] Next, the granulated particles were filled into a φ25 mm mold and uniaxially molded at 6 MPa to adjust the overall shape, after which they were packed into a rubber bag and CIP molded at 200 MPa.

[0032] The above molded body was subjected to a degreasing treatment in the air at 600°C for 2 hours, and then fired in an argon atmosphere at 1000°C for 2 hours to obtain a sintered body of yttrium oxyfluoride. The obtained sintered body of yttrium oxyfluoride was in the form of a plate having a diameter of 19 mm and a thickness of 3 mm. An electron microscope photograph was also taken at a magnification of 500 times under the conditions described below, and the average particle size of the Y5O4F7 crystals was measured from this electron microscope photograph using the method for measuring average particle size described below, which was found to be 85.1 μm. The electron microscope photograph is shown in Figure 1.

[0033] (Test Example 1) 36.3 parts by weight of Y2O3, 63.7 parts by weight of YF3 (molar ratio of Y2O3:YF3=100:270, i.e., the composition after the firing reaction is molar ratio of Y5O4F7:YF3=100:35), 3.0 parts by weight of acrylic resin as an organic binder, and 40 parts by weight of an alcohol-based solvent as a dispersion medium were mixed, and then the mixture was dried at 70°C using a spray dryer and granulated to prepare a granular raw material composition. The particle size of the obtained granular particles was adjusted by cutting (removing) particles with a particle size of 80 μm or more.The alcohol solvent was 86 wt % ethanol and 14 wt % isopropyl alcohol.

[0034] Next, the granulated particles were filled into a φ25 mm mold and uniaxially molded at 6 MPa to adjust the overall shape, after which they were packed into a rubber bag and CIP molded at 200 MPa.

[0035] The above-mentioned molded body was subjected to a degreasing treatment in the air at 600°C for 2 hours, and then fired in an argon atmosphere at 950°C for 2 hours to obtain a sintered body of yttrium oxyfluoride. The obtained sintered body of yttrium oxyfluoride was in the form of a plate having a diameter of 19 mm and a thickness of 3 mm. In addition, an electron microscope photograph was taken at a magnification of 5000 times under the conditions for electron microscope photographs described later, and the average particle size of the Y5O4F7 crystals was measured from this electron microscope photograph according to the method for measuring average particle size described later, and was found to be 3.0 μm. The electron microscope photograph is shown in Figure 2.

[0036] (Comparative Example 1) A plate of sintered Y2O3 (N-100Y manufactured by Nishimura Ceramics) was cut into a size of 20 mm x 20 mm using a diamond cutter, and then polished to a thickness of 1 mm using a diamond lapping polisher.

[0037] The obtained sintered bodies of Example 1, Test Example 1, and Comparative Example 1 were subjected to etching treatment using CF4 plasma and O2 plasma under the following conditions, and the etching amount for each was shown in Table 1, assuming that the etching amount for Comparative Example 1 was 1.

[0038] (Electron microscope imaging conditions) Equipment: Hitachi High-Tech S-4800 Accelerating voltage: 3.0 kV Magnification: 500x and 5000x

[0039] (Measuring conditions for average particle size) The surfaces of the sintered bodies of Example 1 and Test Example 1 were polished to a mirror finish using a diamond lapping polisher. They were observed under an electron microscope (under the above conditions) at 500x or 5000x magnification, and the major axes of any 10 particles observed within the field of view were measured, and the average value over four fields of view was taken as the average particle diameter. However, if the overall diameters of all 10 particles could not be confirmed within one field of view, another field of view was additionally observed to confirm the diameters of the 10 particles.

[0040] (Plasma etching conditions) Plasma etching equipment: EXAM manufactured by Shinko Seiki Co., Ltd. Etching method: parallel plate type (Capacitive Coupled Plasma-RIE) RIE is an abbreviation for Reactive Ion Etching. Substrate temperature: 20℃ Power supply: High frequency 13.56MHz Power: 350W Etching time: 6 hours Samples: The sintered bodies of Example 1 and Test Example 1 were polished with a diamond lapping polisher to a thickness of 1 mm, and masking tape (Kapton tape) was attached to the plasma contact surface of each of the sintered bodies of Example 1, Test Example 1, and Comparative Example 1. The area covered with Kapton tape was not etched, so this area served as the reference surface. The difference in level between the reference surface and the etched area was measured as the amount of etching. The difference in level was measured with a laser microscope (KEYENCE VK-X200 series).

[0041] [Table 1]

[0042] As shown in Table 1, the etching amount of the sintered body according to Comparative Example 1 was the largest, followed by the etching amount of the sintered body according to Test Example 1, and the etching amount of the sintered body according to Example 1 was the smallest. In other words, it can be said that the sintered body according to Example 1 is a sintered body with high corrosion resistance to CF4 plasma and O2 plasma.

[0043] FIG. 1 is an electron microscope photograph of the surface of the sintered body of yttrium oxyfluoride (Y5O4F7) according to Example 1. FIG. 2 is an electron microscope photograph of the surface of the yttrium oxyfluoride sintered body (Y5O4F7) according to Test Example 1.

[0044] Furthermore, powder X-ray diffraction (XRD) was performed on the sintered bodies obtained in Example 1 and Test Example 1 under the following conditions to obtain powder X-ray diffraction charts. FIG. 3 is a powder X-ray diffraction chart of the sintered body according to Test Example 1, and FIG. 4 is a powder X-ray diffraction chart of the sintered body according to Example 1. The crystal structure of Y5O4F7 was confirmed in both charts. Furthermore, while peaks of YF3 were observed in the powder X-ray diffraction chart shown in FIG. 4, neither peaks due to YF3 nor peaks due to impurity crystals were observed, and only the crystal structure of Y5O4F7 was confirmed. The crystal structure of Y5O4F7 in Figures 3 and 4 was identified using JCPDS card number 01-080-1124. The crystal structure of YF3 in Figure 3 was identified using JCPDS card number 32-1431.

[0045] The measurement conditions for powder X-ray diffraction are as follows. Equipment: Rigaku SmartLab Voltage: 40kV, Current: 20mA X-ray source:CuKα Scanning range: 2θ=10~70° Scanning speed: 10° / min

[0046] As can be seen from Example 1 and Test Example 1, the Y5O4F7 sintered body of Example 1 has a large average grain size of Y5O4F7 crystals at 85.1 μm, a relatively lower density of triple junctions per unit area than the Y5O4F7 sintered body of Test Example 1, and is therefore less susceptible to corrosion originating from triple junctions due to CF4 plasma and O2 plasma. Furthermore, impurity crystal particles such as YF3 crystal particles are absent, or their abundance is suppressed to an extent that they are not detectable by powder X-ray diffraction. This prevents preferential corrosion due to plasma that occurs at the grain boundaries between impurity crystal particles other than Y5O4F7, such as YF3 crystals, and Y5O4F7. Therefore, the sintered body of Example 1 can be said to be suitable for use in a plasma atmosphere.

Claims

1. Yttrium oxyfluoride (Y ５ O ４ F ７ ) in the sintered body, ５ O ４ F ７ ) having an average grain size of 70 μm or more and 100 μm or less.

2. The yttrium oxyfluoride (Y ５ O ４ F ７ In the powder X-ray diffraction chart of the sintered body made of yttrium fluoride (YF ３ 2. The sintered body according to claim 1, wherein no peaks due to crystals of

3. The powder X-ray diffraction chart of the sintered body according to claim 2 is measured under the conditions of a powder X-ray diffractometer using CuKα rays, an X-ray tube voltage of 40 kV, a current of 20 mA, a scanning range of 2θ = 10 to 70°, and a scanning speed of 10° / min.

4. The powder X-ray diffraction chart of the sintered body shows that yttrium oxyfluoride (Y ５ O ４ F ７ 4. The sintered body according to claim 1, wherein only peaks based on crystalline sintered bodies are observed.

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

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