YAG sintered body, its manufacturing method, semiconductor manufacturing equipment component, and gas nozzle

Abstract

To provide a YAG sintered compact that is excellent in plasma resistance even on a machined surface, exhibits particle suppression effects, and can be applied as a member for a semiconductor manufacturing apparatus.SOLUTION: The present invention relates to a YAG sintered compact, wherein an arithmetic average roughness Ra is Ra≤0.5 μm and a ratio of a maximum height Rz to a maximum valley depth Rv is Rv / Rz≤0.7 on a specified surface where pores within grains are exposed. Accordingly, the specified surface of the machined surface becomes smooth, plasma resistance is improved, and particle suppression effect is exhibited.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a YAG sintered body, a method for producing the same, a semiconductor manufacturing equipment member using the YAG sintered body, and a gas nozzle. [Background technology]

[0002] Conventionally, in semiconductor manufacturing equipment, when forming a thin film on the surface of a substrate by chemical vapor deposition (CVD) or when microfabrication of the thin film by etching is performed, plasma gas is introduced into a reaction vessel that houses the substrate. Therefore, components such as the reaction vessel and the gas nozzle for introducing the plasma gas into the reaction vessel must have good resistance (plasma resistance) to halogen gases such as plasmatized fluoride gas.

[0003] Patent Document 1 discloses an alumina ceramic sintered body obtained by sintering an alumina ceramic green body formed into a desired shape, or by further grinding the sintered body, and then heat treating the sintered body at 1000 to 1550°C for 0.1 to 6 hours.

[0004] Patent Document 2 describes a method for forming a surface exposed to plasma in a corrosive gas atmosphere such as a fluorine-based or chlorine-based gas, using yttrium aluminum garnet (YAG: Y3Al5O 12 ) sintered body and has a centerline average roughness (Ra) of 1 μm or less.

[0005] Patent Document 3 also discloses a gas nozzle that includes a columnar body made of a sintered ceramic body with a through hole formed therein through which gas flows, one end face of the body having a gas outlet for the through hole, the inner wall of the through hole having a first region located near the outlet and a second region located further inside the body than the first region, the first region and the second region being made of the sintered surface of the ceramic body, and the average crystal grain size in the first region being larger than the average crystal grain size in the second region. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 08-081258 [Patent Document 2] Japanese Patent Application Publication No. 10-236871 [Patent Document 3] Patent No. 6046752 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the alumina sintered body described in Patent Document 1 may have insufficient plasma resistance when used as a component for semiconductor manufacturing equipment. Furthermore, the YAG sintered body described in Patent Document 2 may be subjected to surface processing such as grinding or polishing to achieve the desired shape or surface roughness, but processing damage increases the risk of particles falling off the processed surface due to plasma. Furthermore, depending on the manufacturing conditions, Al2O3 segregation may occur at the grain boundaries of the sintered body, and since Al2O3 has lower plasma resistance than YAG, differences in plasma resistance at the grain boundaries occur.

[0008] Furthermore, when the surface is a sintered surface, as in the gas nozzle described in Patent Document 3, processing after sintering is not possible, so when the nozzle has a complex flow path or is a small component with a narrow flow path, it is difficult to control shrinkage during sintering, and there is a risk that the precision of the flow path will be reduced.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a YAG sintered body that has excellent plasma resistance even on the processed surface, exhibits particle suppression effects, and can be used as a component for semiconductor manufacturing equipment. [Means for solving the problem]

[0010] (1) In order to achieve the above object, the present invention provides the following means: The YAG sintered body of the present invention is a YAG sintered body characterized in that, on a predetermined surface where intragranular pores are exposed, the arithmetic mean roughness Ra satisfies Ra≦0.5 μm and the ratio of maximum height Rz to maximum valley depth Rv satisfies Rv / Rz≦0.7.

[0011] In this way, when the arithmetic mean roughness Ra satisfies Ra≦0.5 μm and the ratio of the maximum height Rz to the maximum valley depth Rv satisfies Rv / Rz≦0.7 on a given surface where intragranular pores are exposed, the given surface of the machined surface becomes smooth, plasma resistance is improved, and particle suppression effects are exerted.

[0012] (2) Furthermore, the YAG sintered body of the present invention is the YAG sintered body described in (1) above, characterized in that the number of intragranular pores observed within an area of ​​80 μm × 60 μm on the specified surface is 40 or less.

[0013] In this way, by limiting the number of intragranular pores observed within an area of ​​80 μm×60 μm on a given surface to 40 or less, the plasma resistance of the given surface can be further improved.

[0014] (3) Furthermore, the YAG sintered body of the present invention is the YAG sintered body described in (1) above, characterized in that the area ratio of aluminum oxide observed within an area of ​​80 μm × 60 μm on the specified surface is 2.0% or less.

[0015] In this way, by setting the area ratio of aluminum oxide observed within an 80 μm×60 μm area on a given surface to 2.0% or less, the plasma resistance of the given surface can be further improved.

[0016] (4) Furthermore, the YAG sintered body of the present invention is the YAG sintered body described in (2) above, characterized in that the area ratio of aluminum oxide observed within an area of ​​80 μm × 60 μm on the specified surface is 2.0% or less.

[0017] In this way, by setting the area ratio of aluminum oxide observed within an 80 μm×60 μm area on a given surface to 2.0% or less, the plasma resistance of the given surface can be further improved.

[0018] (5) A member for semiconductor manufacturing equipment according to the present invention is characterized by comprising the YAG sintered body according to any one of (1) to (4) above.

[0019] In this way, by making the YAG sintered body of the present invention into a semiconductor manufacturing equipment component, the plasma resistance of the processed surface can be improved even after processing the YAG sintered body, and it can be suitably used as a semiconductor manufacturing equipment component that requires plasma resistance.

[0020] (6) A gas nozzle according to the present invention is a gas nozzle used in a semiconductor manufacturing apparatus, characterized in that the member for semiconductor manufacturing apparatus described in (5) above is used.

[0021] In this way, the semiconductor manufacturing equipment member made of the YAG sintered body of the present invention can be used, for example, as a gas nozzle for introducing corrosive gas into a reaction vessel. Since the YAG sintered body of the present invention can improve the plasma resistance of the processed surface after sintering, it can easily be used even for gas nozzles with narrow and complicated gas flow paths.

[0022] (7) The method for producing a YAG sintered body of the present invention is characterized by comprising the steps of preparing a YAG sintered body, processing a predetermined surface of the YAG sintered body to Ra 0.5 μm or less, and heat treating the processed YAG sintered body at a temperature of 1400°C or higher and 1700°C or lower for one hour or longer.

[0023] In this way, by processing a specified surface to Ra 0.5 μm or less and heat-treating it at a temperature of 1400°C to 1700°C for at least one hour, the plasma resistance of the specified surface can be improved, and the YAG sintered body described in (1) to (4) above and components for semiconductor manufacturing equipment, gas nozzles, etc., can be manufactured using this sintered body. Furthermore, processing can be performed after sintering, improving the plasma resistance of the processed surface. Therefore, there is no need to strictly control the shrinkage rate of the molded body during sintering, and precision structures can be manufactured even for small structures with complex flow paths or narrow flow paths. [Effects of the Invention]

[0024] According to the YAG sintered body of the present invention, it is possible to ensure plasma resistance of a predetermined surface among the processed surfaces of the YAG sintered body, and to reduce the risk of particle generation. [Brief explanation of the drawings]

[0025] [Figure 1] This is a diagram showing the positions of grain boundary pores and intragranular pores in an SEM image of the surface of a YAG sintered body. [Figure 2] 1 is a schematic cross-sectional view showing an example of use of a semiconductor manufacturing equipment member according to an embodiment of the present invention. [Figure 3] 1(a) to 1(f) are SEM images of predetermined surfaces of the YAG sintered bodies of Comparative Example 1, Examples 1 to 4, and Comparative Example 2, respectively. [Figure 4] 1 is a table showing test results of Examples and Comparative Examples. [Figure 5] 1 is a table showing the test results of Example 3 and Example 3-2. [Figure 6] 1 is a table showing the test results of Example 3 and Example 3-3. DETAILED DESCRIPTION OF THE INVENTION

[0026] Next, an embodiment of the present invention will be described. In the structural diagrams, the sizes of the components are shown conceptually and do not necessarily represent the actual dimensional ratios.

[0027] [Composition of YAG sintered body] (Embodiment) The YAG sintered body of the present invention has a predetermined surface where intragranular pores are exposed, where the arithmetic mean roughness Ra is Ra≦0.5 μm and the ratio of maximum height Rz to maximum valley depth Rv is Rv / Rz≦0.7. The predetermined surface where intragranular pores are exposed is a processed surface that has been ground, polished, or otherwise processed after sintering the YAG sintered body, and is a portion that is expected to be directly exposed to corrosive gases. An example of a predetermined surface where intragranular pores are exposed is the gas outlet of a gas nozzle.

[0028] Pores in sintered bodies are formed by the state of the raw material powder, mixing conditions, sintering conditions, etc. in the manufacturing process. Among these, grain boundary pores are present on the sintered surface, but intragranular pores are not present on the sintered surface. Almost Pores remaining within the grains (intragranular pores) are exposed to the surface when the sintered body is processed into a predetermined shape or when through-holes are formed. There is a risk that the processed surface with exposed intragranular pores will have reduced plasma resistance.

[0029] Furthermore, after the YAG sintered body is sintered, the surface condition of the processed surface suffers from processing damage such as microcracks and grain defects. Therefore, even if the surface is processed to a surface roughness (Ra) similar to that of the sintered surface, the plasma resistance is sometimes not improved. There are various possible reasons for this, but the inventors have hypothesized that one of the causes is the increase in the maximum valley depth (Rv) due to surface processing, in addition to the exposure of intragranular pores.

[0030] While the maximum peak height (Rp) can be controlled to some extent by surface processing, the maximum valley depth (Rv) is difficult to control by processing such as polishing. If deep portions exist on the surface of a sintered body, there is a possibility that debris generated during processing may get trapped there. If debris that gets trapped in the grooves is not completely removed when the component is cleaned, there is a risk that it will fall off as particles during actual use. Furthermore, if the maximum valley depth (Rv) is large, the valleys will become even deeper when eroded by plasma, increasing the risk of particle generation.

[0031] The inventors discovered that by heat treating a YAG sintered body at a predetermined temperature after processing, it is possible to reduce Rv / Rz without significantly changing Ra, and improve the plasma resistance of the processed surface, and thus completed the present invention.

[0032] The YAG sintered body of the present invention has an arithmetic mean roughness (Ra) of Ra≦0.5 μm on the predetermined surface where the intragranular pores are exposed, and the ratio of the maximum height (Rz) (μm) to the maximum valley depth (Rv) (μm) satisfies Rv / Rz≦0.7. This surface condition results in a smooth surface, improving plasma resistance and suppressing particle generation. Furthermore, the shallow maximum valley depth (Rv) relative to the maximum height (Rz) improves the cleanability of the component. These roughnesses can be confirmed using a stylus-type surface roughness tester (compliant with JIS B 0601). The YAG sintered body of the present invention may or may not satisfy the requirements of Ra≦0.5 μm and Rv / Rz≦0.7 on surfaces other than the predetermined surface. Furthermore, the surfaces other than the predetermined surface may be machined surfaces or annealed surfaces.

[0033] The YAG sintered body of the present invention is mainly composed of yttrium aluminum garnet (hereinafter referred to as YAG). The term "mainly composed of YAG" means that the sintered body contains YAG (Y3Al5O 12) is contained in an amount of 93.0 wt% or more. Components other than YAG may include, for example, composite oxides of Y and Al, such as YAM, YAP, YO, and AlO, or oxides of Y and Al. In addition, specific metal elements or metal oxides may be added to impart specific functions to the YAG sintered compact.

[0034] Intragranular pores exposed on a given surface are more susceptible to plasma erosion than other areas and can cause particle generation. Therefore, it is preferable that their number be small. The YAG sintered body of the present invention preferably has 40 or fewer intragranular pores observed within an 80 μm × 60 μm area on the given surface. This further improves the plasma resistance of the given surface. The number of intragranular pores can be reduced by aligning the average particle size of the raw material powder or by slowing the heating rate during sintering. However, even with strict control of the manufacturing process, it is not possible to eliminate intragranular pores. Therefore, the number of intragranular pores observed within an 80 μm × 60 μm area is usually three or more.

[0035] The number of intragranular pores observed within an 80 μm x 60 μm area on a given surface is determined by taking an image of the surface using a scanning electron microscope (SEM), randomly selecting three 80 μm x 60 μm fields of view, and averaging the number of intragranular pores observed in each field of view. Figure 1 shows the locations of intergranular pores and intragranular pores in an SEM image of the surface of a YAG sintered compact. As such, intergranular pores and intragranular pores can easily be identified as different entities in an SEM image.

[0036] Localized structural irregularities due to the segregation of aluminum oxide (Al2O3) alone may occur at the grain boundaries of YAG sintered bodies. Since the parts present as aluminum oxide alone have lower plasma resistance than the parts present as other YAG, they are susceptible to plasma erosion and can cause particle generation. Therefore, it is preferable to minimize such segregated parts.

[0037] In the YAG sintered body of the present invention, the area ratio of aluminum oxide observed within an 80 μm × 60 μm area on a predetermined surface is preferably 2.0% or less. This further improves the plasma resistance of the predetermined surface. Furthermore, if the condition of the predetermined surface exposed to at least corrosive gases satisfies an arithmetic mean roughness Ra of 0.5 μm or less and a ratio Rv / Rz (maximum height (Rz) to maximum valley depth (Rv)) of 0.7 or less, the segregated portions are in good contact with adjacent YAG particles, making it difficult for particles to fall off due to plasma erosion of the segregated portions. Aluminum oxide segregation can be reduced by increasing the mixing time of the raw material powder.

[0038] The area percentage of aluminum oxide on a given surface can be confirmed as follows. First, a given surface of a YAG sintered body is photographed with a scanning electron microscope (SEM) at 2000x magnification. Next, areas of a given color tone in the SEM image are confirmed to be aluminum oxide segregation. To do this, the same surface is subjected to EDS analysis to confirm the Y, Al, and O peaks of the given area. If no Y peak is observed in the given area but peaks of Al and O are confirmed, the given area can be identified as aluminum oxide segregation. The photographed image is then subjected to image processing such as binarization using image analysis software WinROOF (manufactured by Mitani Shoji Co., Ltd.), and the area percentage of the given color tone is determined. Note that the area percentage of aluminum oxide observed within an 80 μm × 60 μm area on the given surface is defined as 2.0% or less when the area percentages determined in each of three randomly selected visual fields are 2.0% or less.

[0039] The YAG sintered compact preferably contains 1000 ppm or less of metal elements, excluding yttrium and aluminum. By keeping the total content of metal elements, excluding yttrium and aluminum, at 1000 ppm or less, plasma resistance can be sufficiently ensured. Examples of metal elements, excluding yttrium and aluminum, include Si, Ca, Na, Mg, Ti, Cr, Fe, Ni, Cu, and P. Metalloid elements, such as Si and P, are also included in the metal elements of the present invention. Furthermore, if specific metal elements or metal oxides are added to impart specific functions to the YAG sintered compact, these metal elements are excluded from the above amounts. Materials added to impart specific functions to the YAG sintered compact can be added in amounts of 0.1 wt% or more.

[0040] These trace metals tend to condense mainly in the grain boundary layers of YAG sintered bodies, making them more susceptible to corrosion in a plasma environment than YAG. If the corrosion of trace metal components progresses first, the corrosion of the grain boundaries causes particle shedding, resulting in a deterioration of plasma resistance. For this reason, it is preferable to keep the content of metal elements other than yttrium and aluminum as low as possible. Therefore, the content of metals other than yttrium and aluminum is preferably 500 ppm or less, and more preferably 300 ppm or less. The lower limit of the content of metal elements other than yttrium and aluminum is preferably as low as possible. However, since impurities may be unavoidably present in the raw material powder or during the manufacturing process, the content can be set to, for example, 1 ppm or more. Note that in order to keep the trace metal content within the above range, it is necessary to control the raw material powder or manufacturing process to prevent impurities from being mixed in.

[0041] The contents of yttrium and aluminum in the YAG sintered body in terms of oxides, and the contents of metal elements other than yttrium and aluminum contained in the YAG sintered body can be measured by glow discharge mass spectrometry (GD-MS).

[0042] The YAG sintered body preferably has a relative density of 98% or more. By making the relative density sufficiently high, plasma resistance can be increased, the strength of the sintered body is excellent, and it can be suitably used as a large component.

[0043] The relative density of a YAG sintered body can be expressed as (sintered body density / theoretical density) × 100 (%). The theoretical density is the density of YAG alone (4.55 g / cm 3 ) and the sintered density was measured by the Archimedes method for the density of the YAG sintered body.

[0044] The YAG sintered body of the present invention has excellent plasma resistance even on the surface processed after firing, so it can be used as a component for semiconductor manufacturing equipment. In particular, it does not require strict control of the shrinkage rate of the molded body during firing, and it is possible to produce precise structures even in cases where the molded body has a complex flow path or a small structure with a narrow flow path, so it is suitable for components for such semiconductor manufacturing equipment, such as gas nozzles.

[0045] [Configuration of semiconductor manufacturing equipment components] Next, a semiconductor manufacturing equipment member of the present invention will be described. Fig. 2 is a schematic cross-sectional view showing an example of use of a semiconductor manufacturing equipment member according to an embodiment of the present invention. The semiconductor manufacturing equipment member of the present invention can be suitably used, for example, as a vessel body 21 or a lid 22 constituting a reaction vessel 20 used in a plasma device 100, such as a film-forming device for forming a thin film on a substrate W, such as a semiconductor wafer or a glass substrate, or an etching device for performing microfabrication on the substrate W, in a semiconductor manufacturing process or a liquid crystal manufacturing process, and can be suitably used particularly as a gas nozzle 10.

[0046] For example, in a film forming apparatus, a source gas containing a corrosive gas is introduced into a reaction vessel 20 using a gas nozzle 10, and a thin film is formed on a substrate W by a plasma CVD (Chemical Vapor Deposition) method in which the source gas is converted into plasma. Also, in an etching apparatus, a halogen-based corrosive gas is introduced into a reaction vessel 20 using a gas nozzle 10 as a source gas, and the corrosive gas is converted into plasma to form an etching gas, thereby performing microfabrication on the substrate W.

[0047] The gas nozzle 10 has a gas supply port 11 through which gas such as a corrosive gas is supplied from a gas supply unit not shown, a gas exhaust port 12 through which gas is discharged into the reaction vessel 20, and a nozzle hole 13 that connects the gas supply port 11 and the gas exhaust port 12.

[0048] The semiconductor manufacturing equipment member according to the embodiment of the present invention is a member having a portion exposed to a corrosive gas or a corrosive chemical, and in this case, is a member constituting at least a portion of the portion of the gas nozzle 10 exposed to the corrosive gas, for example, the portion including the nozzle hole 13, or the portion exposed inside the reaction vessel 20. However, the semiconductor manufacturing equipment member may also constitute the entire gas nozzle 10. Furthermore, the semiconductor manufacturing equipment member may be, for example, the vessel body 21 or the lid 22 constituting the reaction vessel 20, or a portion thereof.

[0049] By using the YAG sintered body of the present invention as a semiconductor manufacturing equipment component, plasma resistance as a semiconductor manufacturing equipment component can be ensured even if the surface is processed after firing, and the risk of particle generation can be reduced. Furthermore, even if a complex flow path is formed after firing or a small structure with a narrow flow path is formed, plasma resistance can be ensured.

[0050] [Manufacturing method for YAG sintered body] Next, a method for manufacturing a YAG sintered body of the present invention will be described. The method for manufacturing a YAG sintered body of the present invention includes the steps of preparing a YAG sintered body before heat treatment, processing the prepared YAG sintered body, and heat treating the processed YAG sintered body. The step of preparing a YAG sintered body before heat treatment can be performed by a conventional manufacturing method, for example, forming a molded body by a casting method or a CIP molding method, and firing it to obtain a sintered body. An example of the step of preparing a YAG sintered body before heat treatment will be described below.

[0051] First, yttrium oxide powder and aluminum oxide powder are prepared as raw material powders for the YAG sintered body. The purity of each powder is preferably 99.9% or higher, more preferably 99.99% or higher. The average particle size of each powder is preferably 0.1 μm or higher and 10 μm or lower.

[0052] Next, yttrium oxide powder and aluminum oxide powder are weighed out so that the YAG sintered body will have the desired composition ratio, calculated as oxides, after sintering. The desired composition ratio is 37.5 mol% Y, calculated as oxide (YO), and 62.5 mol% Al, calculated as oxide (AlO). While deviations of approximately 1.0 mol% are permitted, it is preferable to keep the composition ratio as close to the desired ratio as possible. The desired composition ratio, in terms of the weight ratio of yttrium oxide powder to aluminum oxide powder, is approximately 57:43.

[0053] Next, the raw material powders are mixed. Each powder is placed in a pot together with a binder (PVA, etc.), and then crushed and mixed by wet mixing using a ball mill to prepare a raw material slurry. Ion-exchanged water or a dispersant may be used to prepare the raw material slurry. For example, resin balls may be used in the ball mill. The mixing time is preferably, for example, from 15 hours to 45 hours.

[0054] Next, the slurry obtained in the mixing step is dried and granulated. For example, a method for obtaining a granulated powder from the slurry can be mentioned in which the slurry is dried in a hot water bath to remove the solvent from the slurry, and the obtained powder is passed through a sieve. Alternatively, a spray dryer can be used.

[0055] Next, the granulated powder obtained in the granulation step is molded to form a compact. As a molding method, a method of putting the granulated powder obtained into a mold and press-molding can be used. As a press-molding method, known methods such as uniaxial press molding, cold isostatic pressing (CIP), and hot press can be used. In addition, in the case of press molding, the molding pressure can be, for example, 98 MPa.

[0056] Next, the compact is fired. The compact is fired in an oxidizing atmosphere or a vacuum atmosphere at a temperature of 1600°C to 2000°C, thereby obtaining a YAG sintered compact before heat treatment. The firing time is preferably 1 hour to 20 hours. The temperature rise rate is preferably, for example, 30°C / hour to 100°C / hour. If necessary, a degreasing step may be added before the firing step. Also, a step of compressing the YAG sintered compact using a hot isostatic press (HIP) to densify it may be added. By such steps, a YAG sintered compact before heat treatment can be prepared.

[0057] In the process of processing the prepared YAG sintered body, the predetermined surface of the prepared YAG sintered body is processed to Ra 0.5 μm or less. The reason for making the arithmetic mean roughness Ra sufficiently small at this stage is that Ra does not change significantly in the heat treatment process. The processed surfaces other than the predetermined surface may or may not be processed to Ra 0.5 μm or less.

[0058] The heat treatment process involves heat-treating the processed YAG sintered compact at a temperature between 1400°C and 1700°C for at least one hour. The heat treatment atmosphere is preferably an oxidizing atmosphere or a vacuum atmosphere. By including this heat treatment process, the surface condition of the processed surface can be improved, even if the sintered YAG sintered compact is subjected to post-processing, and plasma resistance can be improved. Furthermore, there is no need to strictly control the shrinkage rate of the compact during sintering, making it possible to fabricate precise structures even in cases where the compact has complex flow paths or small structures with narrow flow paths.

[0059] By such a process, it is possible to ensure plasma resistance of a predetermined surface among the processed surfaces of the YAG sintered body, and to manufacture a YAG sintered body that can reduce the risk of particle generation.

[0060] [Examples and Comparative Examples] Example 1 The yttrium oxide raw material powder (purity 99.9%, average particle size 1 μm) and aluminum oxide powder (purity 99.99%, average particle size 0.5 μm) were weighed out so that the weight ratio of yttrium oxide raw material powder (purity 99.9%; average particle size 0.5 μm) to aluminum oxide powder was 57:43.

[0061] Next, the weighed raw material powder was added to a pot along with 2.0 wt% of a PVA binder as a binder, 0.3 wt% of a water-soluble acrylic dispersant as a dispersant, and an appropriate amount of ion-exchanged water, and then wet-mixed in a ball mill using resin balls to form a raw material slurry. The mixing time was 36 hours.

[0062] Next, this raw material slurry was dried and granulated using a spray dryer, and the granulated powder was placed in a mold and formed into a compact using cold isostatic pressing (CIP). The formed compact was then sintered at 1700°C in air for 10 hours at a heating rate of 60°C / hour. Several test pieces measuring 50mm square and 2mm thick were cut out from the sintered YAG compact.

[0063] Next, the cut-out test pieces were subjected to surface grinding and polishing. The surface grinding and polishing were performed so that the surface roughness Ra of the specified surface was 0.5 μm or less. Next, the processed YAG sintered body was heat-treated in an oxidizing atmosphere at a temperature of 1400 °C for 1 hour. In this way, the test piece of the YAG sintered body of Example 1 was produced.

[0064] Example 2 A test piece of the YAG sintered body of Example 2 was prepared under the same conditions as in Example 1, except that the heat treatment temperature was set to 1500°C.

[0065] Example 3 A test piece of the YAG sintered compact of Example 3 was prepared under the same conditions as in Example 1, except that the heat treatment temperature was set to 1600°C.

[0066] Example 4 A test piece of the YAG sintered compact of Example 4 was prepared under the same conditions as in Example 1, except that the heat treatment temperature was set to 1700°C.

[0067] (Comparative Example 1) A test piece of the YAG sintered body of Comparative Example 1 was prepared under the same conditions as in Example 1, except that no heat treatment was carried out after the surface grinding and polishing.

[0068] (Comparative Example 2) The surface of the compact was processed, but after firing at 1700°C, no surface grinding, polishing, or heat treatment was performed. A test piece of the YAG sintered compact of Comparative Example 2 was prepared. The weighing, mixing, and firing conditions were the same as those of Example 1.

[0069] (Comparative Example 3) A test piece of the YAG sintered compact of Comparative Example 3 was prepared under the same conditions as in Example 1, except that the heat treatment temperature was set to 1300°C.

[0070] Comparative Example 4 A test piece of the YAG sintered compact of Comparative Example 4 was prepared under the same conditions as in Example 1, except that the heat treatment temperature was set to 1800°C.

[0071] (Example 3-2) A YAG sintered body was produced using the same raw materials and conditions as in Example 1, except that the heating rate during sintering was 100°C / hour. A test piece was cut out from the sintered body, and a YAG sintered body of Example 3-2 was produced under the same conditions as in Example 3.

[0072] (Example 3-3) A YAG sintered body was produced using the same raw materials and conditions as in Example 1, except that the mixing time of the raw material powder of the YAG sintered body was 15 hours. A test piece was cut out from the sintered body, and a YAG sintered body of Example 3-3 was produced under the same conditions as in Example 3.

[0073] [Evaluation method] (Surface condition (roughness)) For each test piece of the examples and comparative examples, the arithmetic mean roughness (Ra), maximum height (Rz), and maximum valley depth (Rv) were measured before and after the heat treatment. The arithmetic mean roughness (Ra), maximum height (Rz), and maximum valley depth (Rv) were measured using a stylus-type surface roughness meter (in accordance with JIS B 0601).

[0074] (Number of intragranular pores) For each test piece in the examples and comparative examples, the number of intragranular pores on a predetermined surface was calculated after heat treatment. To calculate the number of intragranular pores, a scanning electron microscope (SEM) was used to photograph a predetermined surface of each test piece at 2000x magnification, and the number of intragranular pores in a field of view of 80 μm × 60 μm was confirmed. The number of intragranular pores was determined by photographing three randomly selected locations on each test piece and rounding up the decimal point of the average number of intragranular pores observed.

[0075] (area ratio of aluminum oxide) For each test piece in the examples and comparative examples, the area percentage of aluminum oxide (Al2O3) on a predetermined surface after heat treatment was calculated. To calculate the area percentage of aluminum oxide, a scanning electron microscope (SEM) was used to photograph a predetermined surface of each test piece at 2000x magnification, and the area percentage of simple aluminum oxide present at the grain boundaries was confirmed. EDS analysis was used to confirm in advance that areas with a predetermined color tone in the SEM image were aluminum oxide, and image processing such as binarization was performed using the image analysis software WinROOF to confirm this. The area percentage of aluminum oxide was determined by photographing three randomly selected areas of the test piece, and the maximum area percentage confirmed was used as the area percentage.

[0076] [Evaluation results] Figures 3(a) to (f) are SEM images of the surfaces of the YAG sintered bodies of Comparative Example 1, Examples 1 to 4, and Comparative Example 2, respectively. Figure 3(a) shows no heat treatment after surface processing. Figures 3(b) to (e) show the heat treatment temperature gradually increasing after surface processing. Figure 3(f) shows the appearance of the hardened surface without surface processing. As can be seen from these, as the heat treatment temperature is increased from the processed surface that was not heat treated after surface processing, the surface condition of the processed surface approaches that of a hardened surface. This is numerically represented by the Ra value and the Rv / Rz value.

[0077] 4 to 6 are tables showing the test results for the examples and comparative examples. As shown in the table in FIG. 4, the YAG sintered compacts of the present invention did not show a significant change in the arithmetic mean roughness Ra value due to the heat treatment process after surface processing, but the Rv / Rz value decreased due to the heat treatment process. The YAG sintered compacts of Examples 1 to 4 have improved surface conditions compared to Comparative Example 1, which was not heat-treated after surface processing. The Rv / Rz values ​​are 0.7 or less, and plasma resistance is improved. In particular, Examples 3 and 4 have Rv / Rz values ​​similar to Comparative Example 2, ensuring plasma resistance comparable to that of Comparative Example 2. On the other hand, Comparative Example 1 has Rv / Rz values ​​exceeding 0.7 because the processing marks remain intact. Comparative Example 1 has Rv / Rz values ​​exceeding 0.7, which may lead to particle generation originating from the processing marks, resulting in low plasma resistance.

[0078] Examples 1 to 4 and Comparative Examples 3 and 4 showed that the heat treatment temperature is preferably 1400°C or higher and 1700°C or lower. It was found that if the heat treatment temperature is lower than 1400°C, the Rv / Rz value cannot be sufficiently reduced, and plasma resistance may not be sufficiently high. This is thought to be because micrograin growth is not promoted when the heat treatment temperature is low. It was also found that if the heat treatment temperature is higher than 1700°C, the Rv / Rz value cannot be sufficiently reduced, and plasma resistance may not be sufficiently high. This is thought to be because if the heat treatment temperature is high, grain growth is promoted too much, causing changes in the surface condition due to coarse particles, resulting in an increase in Ra.

[0079] Furthermore, in Example 3-2, in which the heat treatment temperature was the same as in Example 3 but the temperature rise rate was changed as a heat treatment condition, the number of intragranular pores increased. The increased intragranular pores make the sample more susceptible to plasma erosion than other areas and can cause particle generation, so it is preferable to minimize the number of intragranular pores exposed on the surface. Note that in Comparative Examples 1 and 3, there was no heat treatment process or the heat treatment temperature was low, making it difficult to measure the intragranular pores due to the surface condition, and therefore measurement was not possible.

[0080] Furthermore, in Example 3-3, in which the heat treatment temperature was the same as in Example 3 but the mixing time of the raw material powder was changed, the area ratio of aluminum oxide increased. Since the part existing as simple aluminum oxide has lower plasma resistance than the part existing as YAG, it is susceptible to erosion by plasma and can cause particle generation, so it was found that it is preferable to keep the area ratio of segregated part existing as simple aluminum oxide as small as possible.

[0081] From the above results, it was confirmed that the YAG sintered body of the present invention has excellent plasma resistance even on the processed surface and is a YAG sintered body that can be used as a member for semiconductor manufacturing equipment.

[0082] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention. [Explanation of symbols]

[0083] 10 Gas Nozzle 11 Gas supply port 12 Gas outlet 13 Nozzle hole 20 reaction vessel 21 Container body 22 Lid 100 Plasma equipment W substrate

Claims

1. A YAG sintered body, On a predetermined surface, the arithmetic mean roughness Ra satisfies Ra≦0.5 μm, and the ratio of the maximum height Rz to the maximum valley depth Rv satisfies Rv / Rz≦0.7 and Rv / Rz≦(68 / 33)Ra, A YAG sintered body characterized in that the number of intragranular pores observed within an area of ​​80 μm×60 μm on the predetermined surface is 3 or more.

2. 2. The YAG sintered body according to claim 1, wherein the number of intragranular pores observed within an area of ​​80 μm×60 μm on the predetermined surface is 40 or less.

3. 2. The YAG sintered body according to claim 1, wherein the area ratio of aluminum oxide observed within an area of ​​80 μm×60 μm on the predetermined surface is 2.0% or less.

4. 3. The YAG sintered body according to claim 2, wherein the area ratio of aluminum oxide observed within an area of ​​80 μm×60 μm on the predetermined surface is 2.0% or less.

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

6. A gas nozzle used in a semiconductor manufacturing apparatus, A gas nozzle comprising the semiconductor manufacturing equipment member according to claim 5.

7. A method for producing a YAG sintered body, comprising: preparing a YAG sintered body containing yttrium aluminum garnet as a main component; a step of processing a predetermined surface of the YAG sintered body to Ra 0.5 μm or less; and heat treating the processed YAG sintered body at a temperature of 1400°C to 1700°C for 1 hour or more.

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