JP2006315955A - Ceramic member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic member of a low cost type, which has excellent plasma resistance and excellent mechanical properties such as bending strength and toughness. <P>SOLUTION: The ceramic member is manufactured by a method having the following steps: a step, wherein a raw material powder is prepared by compounding, for example, 0.1-15 wt.%, expressed in terms of yttria, solution, which contains at least 0.01-1 wt.% magnesia and yttrium, to alumina particles having 0.1-1.0 μm average particle diameter; a step, wherein the raw material powder is molded and the resultant molding is subjected to calcination treatment; and a step, wherein the calcined molding is subjected to a heat treatment in an atmosphere containing a hydrogen gas, to produce yttrium aluminum garnet, and allow the resultant product to leach to the surface and form a film and, simultaneously, sinter the molding. Thus, a YAG layer having ≥2 μm thickness is formed on the surface of the alumina sintered compact. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ceramic member, and more particularly to a ceramic member that not only exhibits excellent plasma resistance in a halogen-based corrosive gas atmosphere but also has excellent mechanical properties.

In the manufacturing process of a semiconductor device, an etching device or a sputtering device that performs fine processing on a semiconductor wafer, a CVD device that forms a film on a semiconductor wafer, or the like is used. And in these manufacturing apparatuses, the structure provided with the plasma generation mechanism is taken for the purpose of high integration. For example, a helicon wave plasma etching apparatus is known as schematically shown in FIG.

  Here, 1 is a processing chamber in which an antenna 2, an electromagnet 3, and a permanent magnet 4 are installed on the outer periphery. The processing chamber 1 has an etching gas supply port 5 and a vacuum exhaust port 6, and a lower electrode 8 that supports the semiconductor wafer 7 is installed in the processing chamber 1. The antenna 2 is connected to a first high-frequency power source 10 via a first matching network 9, and the lower electrode 8 is connected to a second high-frequency power source 12 via a second matching network 11. .

  Etching by this etching apparatus is performed as follows. First, the semiconductor wafer 7 is placed on the lower electrode 8 that supports the semiconductor wafer 7 and the inside of the processing chamber 1 is evacuated, and then an etching gas is supplied. Next, a high frequency current having a frequency of 13.56 MHz is supplied to the antenna 2 and the lower electrode 8 from the corresponding high frequency power supplies 10 and 12 via the matching networks 9 and 11, respectively. On the other hand, a high-density plasma is generated in the processing chamber 1 by passing an electric current through the electromagnet 3, and this plasma energy decomposes the etching gas into an atomic state, and the film formed on the upper surface of the semiconductor wafer 7. Etching is performed.

By the way, this type of manufacturing apparatus uses a corrosive gas such as a chlorine-based gas such as boron chloride (BCl ₃ ) or a fluorine-based gas such as carbon fluoride (CF ₄ ) as an etching gas. Plasma resistance is required for components exposed to plasma in a corrosive gas atmosphere, such as the inner wall portion 1, the monitoring window, the microwave introduction window, and the lower electrode 8. In response to such demands, ceramic members such as alumina-based sintered bodies, silicon nitride-based sintered bodies, and aluminum nitride-based sintered bodies are used as the plasma-resistant member.

  However, ceramic members such as the above-mentioned alumina-based sintered bodies, silicon nitride-based sintered bodies, and aluminum nitride-based sintered bodies gradually corrode when exposed to plasma in a corrosive gas atmosphere. Since the constituting crystal particles are detached, so-called particle contamination occurs. That is, the detached particles adhere to the semiconductor wafer 7, the lower electrode 8, and the like, adversely affect the quality and accuracy of film formation, and there is a problem that the performance and reliability of the semiconductor are easily impaired.

Further, the CVD apparatus is also required to have corrosion resistance because it is exposed to a fluorine-based gas such as fluorine nitride (NF ₃ ) under plasma during cleaning.

  A ceramic member made of a sintered body of yttrium aluminum garnet (so-called YAG) has been proposed to solve the above-mentioned problem of corrosion resistance (Japanese Patent Laid-Open No. 10-236871). That is, the surface exposed to plasma in a halogen-based corrosive gas atmosphere is formed of a yttrium aluminum garnet sintered body having a porosity of 3% or less, and the surface has a center line average roughness (Ra) of 1 μm or less. Members are known.

  However, although this yttrium aluminum garnet sintered body is excellent in terms of plasma resistance, there is a problem that mechanical properties such as bending strength and fracture toughness are inferior. Here, inferior mechanical properties (for example, brittleness) means that the member is likely to be damaged / damaged in the process of cleaning operation, for example, and the material itself is relatively expensive. Together, this leads to an increase in manufacturing cost of manufacturing equipment or semiconductors.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low-cost ceramic member having high plasma resistance and excellent mechanical properties such as bending strength and fracture toughness.

  The invention according to claim 1 is a ceramic member characterized by having a base material substantially made of an alumina sintered body and an yttrium aluminum garnet layer having a thickness of 2 μm or more formed on the surface of the base material.

  According to a second aspect of the present invention, in the ceramic member of the first aspect, the substrate surface is coated with an yttrium aluminum garnet layer so that the alumina crystal particles in the alumina sintered body are not exposed.

  According to a third aspect of the present invention, in the ceramic member according to the first or second aspect, the thickness of the yttrium aluminum garnet layer is 150 μm or less.

  According to a fourth aspect of the present invention, in the ceramic member according to any one of the first to third aspects, the substrate is an alumina sintered body in which the amount of yttrium aluminum garnet increases in a gradient from the inside toward the surface. Features.

  According to a fifth aspect of the present invention, in the ceramic member according to any one of the first to fourth aspects, the amount of yttrium aluminum garnet in the alumina sintered body is 5% by weight or less.

  A sixth aspect of the present invention is the ceramic member according to any one of the first to fifth aspects, wherein the average crystal grain size of the alumina crystal particles in the alumina sintered body is 200 μm or less.

  In the first to sixth aspects of the invention, the reason why the yttrium aluminum garnet layer is leachably coated and formed on the surface of the alumina base material substantially made of an alumina sintered body is considered to be as follows. . That is, the yttrium component present on the surface of the alumina raw material particles is converted into yttrium aluminum garnet by heating, and at the same time, the grain boundary is reduced due to the grain growth of the alumina particles. It is considered that the aluminum garnet gradually moves to the surface of the sintered body.

  In the first to sixth aspects of the invention, the yttrium aluminum garnet layer covering the surface of the alumina base material needs to have a thickness of 2 μm or more. That is, if the thickness is less than 2 μm, the required plasma resistance cannot be sufficiently provided. Further, it is desirable that the alumina substrate surface on which the yttrium aluminum garnet layer is formed is coated so that there is no exposed portion of the alumina substrate. That is, when the alumina base material is exposed, when exposed to plasma in a corrosive gas atmosphere, the exposed portion is locally corroded, and microscopic particles are likely to be generated. Further, the thickness of the yttrium aluminum garnet layer is preferably 150 μm or less. That is, even if it exceeds 150 μm, it is effective, and on the contrary, it becomes an obstacle to cost reduction.

  In addition, the base material substantially composed of an alumina sintered body means that the main component of the base material is an alumina sintered body, and in particular, a sintered body having an alumina composition of 85% by weight or more. Is preferred. And, by forming an yttrium aluminum garnet layer of 2 μm or more on such a substrate surface, particularly preferably, the yttrium aluminum garnet layer is formed so as to be leached and coated during sintering of the alumina sintered body. It functions as a ceramic member having plasma resistance and mechanical properties.

  In the case where the surface of the alumina base material is coated with an yttrium aluminum garnet layer and the alumina base material is an alumina sintered body in which the amount of yttrium aluminum garnet increases gradually from the inside to the surface, the alumina base Since the difference in thermal expansion coefficient between the base material and the yttrium aluminum garnet layer is alleviated, a ceramic member having improved peel resistance in a heating cycle (heat cycle) is formed.

  Here, the amount of yttrium aluminum garnet in the alumina base material is desirably 5% by weight or less, more preferably 3% by weight or less in order to obtain a ceramic member having higher fracture toughness. Further, the inside of the alumina base material means, for example, the vicinity of the center of gravity in the case of a ceramic member in which an yttrium aluminum garnet layer is formed on the entire outer surface of the base material. In addition, in order to impart plasma resistance to only a specific surface of the base material, a member obtained by arbitrarily cutting a ceramic member having a structure in which the entire outer surface is covered with an yttrium aluminum garnet layer is also within the scope of the ceramic member referred to herein. included.

  The alumina base material (sintered body) preferably has an average particle size of the sintered body crystal of 200 μm or less, more preferably 5 to 200 μm, and still more preferably 10 to 40 μm. Here, when the average particle diameter exceeds 200 μm, it becomes difficult to uniformly disperse the yttrium aluminum garnet whose amount gradually increases from the inside toward the surface in the alumina sintered body. That is, local scattering of yttrium aluminum garnet is likely to occur, and it becomes difficult to obtain higher peeling resistance in the heat cycle of the yttrium aluminum garnet layer. Here, the average particle diameter is a value measured by a planimetric method.

  In addition, in the sintering process of the ceramic member, when taking the step of leaching and forming an yttrium aluminum garnet layer on the surface of the alumina base material, magnesia (magnesium sulfate or magnesium nitrate hydrate) or the like may be added. It is preferable to add about 1% by weight to control the growth of crystal grains.

  The ceramic member according to the first to sixth aspects of the invention can be manufactured, for example, as follows. That is, generally, alumina particles having an average particle diameter of 0.1 to 1.0 μm, at least 0.01 to 1% by weight of magnesium compound in terms of magnesia, and 0.1 to 15% by weight in terms of yttria. The raw material powder which added and mixed the yttrium compound was prepared.

  Subsequently, after granulating the raw material powder, the raw material powder is molded, for example, by an isostatic press, and the compact is subjected to a calcination (degreasing) treatment. Thereafter, the calcined molded body is heated in an atmosphere containing hydrogen gas to produce yttrium aluminum garnet, and leached to the surface by grain growth of alumina to form a film. A desired ceramic member can be easily obtained by sintering.

  The granulated raw material powder may be molded by other molding means such as extrusion molding, injection molding, cast molding, etc. instead of being performed by an isostatic press. In preparation of the granulation raw material, instead of producing particles as a solution containing yttrium, a method of adding and blending yttrium or its compound particles (powder) may be adopted if uniform dispersion is possible.

  Here, it is preferable to select the alumina particles as the main component of the raw material powder within a range of an average particle size of about 0.1 to 1.0 μm. The reason is that, in the final sintering process, the crystal grains of alumina cause abnormal growth, and the surface leaching and film formation of yttrium aluminum garnet tend to be impaired.

  Further, the addition of magnesia is for appropriately controlling the crystal particles of the sintered body constituting the base material mainly composed of the alumina, and the composition ratio is selected from 0.01 to 1% by weight. The additive composition of the magnesia component may be a magnesium compound that becomes magnesia by heating, such as magnesium sulfate or magnesium nitrate. However, the addition amount is selected to be 0.01 to 1% by weight in terms of magnesia.

  Furthermore, the addition of a solution containing yttrium produces the required yttrium aluminum garnet and leaches and forms a film on the surface of the alumina-based sintered body, contributing to plasma resistance, and converted to yttria. It is selected to be 0.1 to 15% by weight. The solution containing yttrium is, for example, yttrium nitrate, yttrium acetate, yttrium chloride, or one or more of these hydrates dissolved in pure water or alcohols.

  In the inventions according to claims 7 to 10, for example, preparation of a slurry by stirring and mixing magnesia, yttrium component, binder resin and medium liquid to raw material powder mainly composed of alumina particles is performed by, for example, a rotary ball mill. Moreover, granulation from the prepared slurry is performed by, for example, a spray dryer method. And the shaping | molding which used the obtained granulated powder as a raw material is performed by general pressure molding systems, such as an isostatic pressing, extrusion molding, injection molding, or casting.

  Furthermore, calcination of the molded body using the granulated powder as a raw material is performed at a temperature of about 600 to 1300 ° C. in the atmosphere, and the temperature and time are determined by the shape and dimensions of the molded body. Moreover, sintering after calcination is performed at a temperature of about 1700 to 1850 ° C. in an atmosphere containing hydrogen gas, for example, in a hydrogen stream.

  In addition, this sintering suppresses the rapid growth of crystal grains in the process, but more smoothly generates yttrium aluminum garnet, and promotes leaching / film formation to the surface side of the generated yttrium aluminum garnet. In addition, select and set the temperature increase rate of sintering slightly slower or the sintering time slightly longer.

  In the ninth and tenth aspects of the present invention, the heat treatment for the yttrium aluminum garnet produced in the calcination or sintering process and leached and formed on the surface is performed for the purpose of densifying the yttrium aluminum garnet layer. In other words, when the yttrium aluminum garnet layer leached and formed on the surface of the sintered body is thin or rough, for example, heat treatment is performed at a temperature of 1700 to 1850 ° C., and yttrium is formed on the surface. Since the aluminum garnet layer is softened and remelted to form a dense layer, plasma resistance can be improved.

  The ceramic member can be manufactured by the following procedure. That is, according to the invention of claim 11, an alumina molded body or calcined body containing magnesium and yttrium is prepared, and a powder layer, molded body or calcined body of yttrium aluminum garnet is formed on the surface of the molded body or calcined body. The bodies are stacked and arranged and sintered in an atmosphere containing hydrogen. Alternatively, according to the invention of claim 12, a powder layer, a molded body or a calcined body of yttrium aluminum garnet is laminated and arranged on the surface of a sintered body provided with an yttrium aluminum garnet layer, and in an atmosphere containing hydrogen. Sinter.

  In the first to sixth aspects of the present invention, the base material is essentially formed of an alumina sintered body and the surface is covered with an yttrium aluminum garnet layer. In other words, it is based on an alumina sintered body that has excellent mechanical properties such as bending strength and fracture toughness, while the yttrium aluminum garnet layer with excellent plasma resistance covers the surface exposed to plasma. ing.

  Here, when the substrate is a structure of an alumina sintered body in which the amount of yttrium aluminum garnet is increasing in a gradient from the inside toward the surface, high heat cycle resistance is exhibited. In addition, the above-mentioned yttrium aluminum garnet layer coating improves plasma resistance, eliminates damage and damage during cleaning operations, etc., and has excellent heat cycle resistance with no risk of particle contamination Function as.

  Therefore, it contributes effectively to the manufacture and processing of a semiconductor with high performance and reliability without adversely affecting the quality and accuracy of the film formation while preventing the increase in the manufacturing cost of the manufacturing apparatus or semiconductor.

  According to the above manufacturing method, an yttrium aluminum garnet layer having a surface exposed to plasma having excellent plasma resistance while having an alumina sintered body layer having excellent mechanical properties such as bending strength and fracture toughness as a base material. It is possible to provide a ceramic member having a structure coated with a high yield and mass production. In particular, it is easy to adopt a structure in which the yttrium aluminum garnet layer is leached and formed on the surface of the alumina sintered body in which the amount of yttrium aluminum garnet increases in a gradient from the inside to the surface. The ceramic member which has can be provided.

  According to the first to sixth aspects of the present invention, the base material is an alumina sintered body having excellent mechanical properties such as bending strength and fracture toughness, while the yttrium aluminum garnet layer having excellent plasma resistance covers the surface. It has become the composition. Therefore, the occurrence of damage or damage in the cleaning operation is eliminated, and there is no possibility of causing particle contamination.

  In other words, while suppressing and preventing an increase in manufacturing costs of semiconductor manufacturing equipment or semiconductors, durability that effectively contributes to the manufacture and processing of highly reliable semiconductors without adversely affecting the quality and accuracy of film formation Can be provided. In particular, when the composite layer is interposed between the alumina base material and the yttrium aluminum garnet layer, it exhibits excellent heat cycle resistance, so it can be used for repeated heating and cooling. Suitable.

  Hereinafter, an embodiment will be described with reference to FIG.

  First embodiment

The average relative alumina particles 100 parts by weight of the particle diameter 0.3μm, MgSO ₄ · 7H ₂ O to 750ppm magnesia _{terms, Y (CH 3 COO) 3} · 4H 2 O The composition system of 1.5 parts by weight yttria terms An appropriate amount of ion-exchanged water and 2 parts by weight of polyvinyl alcohol are added to the mixture, and the mixture is stirred and mixed to prepare a slurry. Next, the prepared slurry is granulated with a spray dryer, and the resulting granulated powder is 100 MPa in a hydrostatic pressure press (CIP). A molded body having a thickness of 10 mm, a width of 100 mm, and a length of 100 mm was obtained.

  The molded body was calcined at a temperature of 900 ° C. in the atmosphere, and then sintered at a temperature of 1790 ° C. in a hydrogen gas atmosphere to produce a ceramic member. As a result of identifying this ceramic member by X-ray diffraction (XRD), yttrium aluminum garnet was present in addition to alumina on the surface and inside of the sintered body (ceramic member).

  That is, when the cross section of the sintered body was observed and imaged with an electron microscope, the entire surface of the substrate, which was substantially an alumina sintered body, was covered with an yttrium aluminum garnet layer as shown in FIG. It was confirmed that this was a broken ceramic member. In FIG. 1, the white portion is a yttrium aluminum garnet crystal particle layer, the black portion is an alumina crystal particle, the A portion is an yttrium aluminum garnet layer, and the B portion is a substrate portion substantially made of an alumina sintered body.

  In addition, it is confirmed that the amount of yttrium aluminum garnet increases in an inclined manner from the inside (lower side) of the base material to the surface (upper side). Further, it was confirmed that the surface of the base material was covered with an yttrium aluminum garnet layer having a thickness of 20 to 30 μm so that an exposed portion of the aluminum crystal particles (sintered body) was not present.

  Further, when the average particle diameter of the alumina crystal particles was measured by the planimetric method using the inverted electron image, it was 20 μm. Furthermore, when the inside (center part) of the base material was cut out and ICP emission analysis was performed to measure the amount of yttrium aluminum garnet, it was 0% by weight.

When a 10 × 10 mm square test piece was cut out from the sintered body and the fracture toughness was measured by the IF method using a Vickers indenter, it was 4.0 MPa · m ^1/2 and the fracture toughness value of the alumina sintered body The value was comparable. Further, when the three-point bending strength was measured for both sintered bodies, a value of 350 MPa was shown. In addition, the fracture toughness value of the yttrium aluminum garnet sintered body is a brittle material having a one-to-two MPa · m ^1/2 and a three-point bending strength of about 200 to 300 MPa.

Further, from the sintered body, test pieces having a thickness of 2 mm and a 10 × 10 mm square each having a surface of the sintered body are cut out and attached to a parallel plate type RIE apparatus, with a frequency of 13.56 MHz, a high frequency source 500, and a high frequency bias of 300 W. When the plasma exposure test was conducted under the conditions of CF ₄ / O ₂ / Ar = 30: 20: 50 and gas pressure 0.6665 Pa (5 mTorr), the etching rate (nm / Hr) was 1 or less.

  Further, 10 test pieces each having a thickness of 2 mm and a size of 20 × 20 mm, each having a sintered body surface on one side, were cut out from the sintered body, placed in an atmospheric furnace heated to 400 ° C. for 10 minutes, and taken out of the furnace at room temperature. The heat cycle was cooled to 100 times, but no peeling of the yttrium aluminum garnet layer was observed. In other words, the dense yttrium aluminum garnet layer and the alumina base material on the surface are integrated through a portion where the amount of yttrium aluminum garnet increases in a gradient from the inside to the surface in the alumina base material. Along with this, excellent heat cycle resistance is exhibited. Here, exhibiting excellent heat cycle resistance indicates that it can sufficiently withstand a heat cycle by, for example, plasma radiation (durability).

Second Example With respect to 100 parts by weight of alumina particles having an average particle diameter of 0.3 μm, 750 ppm of MgSO ₄ · 7H ₂ O in terms of magnesia and 3 parts by weight of Y (CH ₃ COO) ₃ • 4H ₂ O in terms of yttria An appropriate amount of ion-exchanged water and 2 parts by weight of polyvinyl alcohol are added to the above composition system, and stirred and mixed to prepare four types of slurry. Next, each of the prepared slurries is granulated with a spray dryer, and the obtained granulated powder is molded with a hydrostatic pressure press (CIP) at a pressure of 100 MPa, and has a thickness of 10 mm, a width of 100 mm, and a length of 100 mm. Each molded body was obtained.

  The molded body was calcined at 900 ° C. in the atmosphere, and then sintered at 1790 ° C. in a hydrogen gas atmosphere to produce a ceramic member. As a result of identifying this ceramic member by X-ray diffraction (XRD), yttrium aluminum garnet was present in addition to alumina on the surface and inside of the sintered body (ceramic member). That is, when the cross section of the sintered body was observed and imaged with an electron microscope, the entire surface of the substrate, which was substantially an alumina sintered body, was covered with an yttrium aluminum garnet layer, as in the first example. It was confirmed that this was a broken ceramic member.

  In this ceramic member, it is confirmed that the amount of yttrium aluminum garnet is increasing in a gradient from the inside (lower side) of the base material to the surface (upper side). Further, it was confirmed that the surface of the base material was covered with an yttrium aluminum garnet layer having a thickness of 20 to 70 μm so that an exposed portion of the aluminum crystal particles (sintered body) was not present.

  Further, when the average particle diameter of the alumina crystal particles was measured by the planimetric method using the inverted electron image, it was 20 μm. Furthermore, the inside (center part) of the base material was cut out and ICP emission analysis was performed to measure the amount of yttrium aluminum garnet. As a result, it was 0.5% by weight.

When a 10 × 10 mm square test piece was cut out from the sintered body and the fracture toughness was measured by the IF method using a Vickers indenter, the fracture toughness of the alumina sintered body was 3.9 MPa · m ^1/2. The value was comparable to the value. Further, when the three-point bending strength was measured for both sintered bodies, a value of 340 MPa was shown.

  Moreover, when a plasma exposure test was performed under the same conditions as in the case of the first example, a test piece having a thickness of 2 mm and a 10 × 10 mm square each having a single-sided sintered body surface was cut out from the sintered body. The etching rate (nm / Hr) was 1 or less in all cases. Similarly, 10 test pieces each having a thickness of 2 mm and a 20 × 20 mm square each having a sintered body surface on one side are cut out from the sintered body, placed in an atmospheric furnace heated to 400 ° C. for 10 minutes, and taken out of the furnace at room temperature. The heat cycle was cooled to 100 times, but no peeling of the yttrium aluminum garnet layer was observed.

  That is, in the ceramic member, the dense yttrium aluminum garnet layer and the alumina base material are integrated through a portion in which the amount of yttrium aluminum garnet is inclined from the inside to the surface in the alumina base material. As a result, excellent heat cycle resistance was exhibited.

Third Example With respect to 100 parts by weight of alumina particles having an average particle diameter of 0.3 μm, 0.1 part by weight of silica particles having an average particle diameter of 0.3 μm and MgSO ₄ .7H ₂ O are converted to 750 ppm in terms of magnesia, Y ( An appropriate amount of ion-exchanged water and 2 parts by weight of polyvinyl alcohol are added to a composition system containing 5.0 parts by weight of CH ₃ COO) ₃ · 4H ₂ O in terms of yttria, and a slurry is prepared by stirring and mixing. Next, the prepared slurry was granulated with a spray dryer, and the obtained granulated powder was molded with a hydrostatic pressure press at a pressure of 100 MPa to obtain a molded body having a thickness of 10 mm, a width of 100 mm, and a length of 100 mm. .

  The molded body was calcined at a temperature of 900 ° C. and then sintered at a temperature of 1790 ° C. in a hydrogen gas atmosphere to obtain a ceramic member. As a result of identifying this ceramic member by X-ray diffraction (XRD), yttrium aluminum garnet was present in addition to alumina on the surface and inside of the sintered body (ceramic member). That is, when the cross section of the sintered body was observed and imaged with an electron microscope, the entire surface of the substrate, which was substantially an alumina sintered body, was covered with an yttrium aluminum garnet layer, as in the first example. It was confirmed that this was a broken ceramic member.

  Further, it is confirmed that the amount of yttrium aluminum garnet in the ceramic member increases in an inclined manner from the inside (lower side) of the base material to the surface (upper side). Furthermore, it was confirmed that the surface of the base material was covered with an yttrium aluminum garnet layer having a thickness of 5 to 50 μm so that no exposed portion of the aluminum crystal particles (sintered body) was present.

  Further, when the average particle diameter of the alumina crystal particles was measured by the planimetric method using the inverted electron image, it was 20 μm. Furthermore, the inside (center part) of the base material was cut out, ICP emission analysis was performed, and the amount of yttrium aluminum garnet was measured and found to be 0.8% by weight.

When a 10 × 10 mm square test piece was cut out from the sintered body and the fracture toughness was measured by the IF method using a Vickers indenter, the fracture toughness of the alumina sintered body was 3.9 MPa · m ^1/2. The value was comparable to the value. Furthermore, when the three-point bending strength of this sintered body was measured, it showed a value of 340 MPa.

  Moreover, when a plasma exposure test was performed under the same conditions as in the case of the first example, a test piece having a thickness of 2 mm and a 10 × 10 mm square each having a single-sided sintered body surface was cut out from the sintered body. The etching rate (nm / Hr) was 1 or less in all cases. Similarly, 10 test pieces each having a thickness of 2 mm and a 20 × 20 mm square each having a sintered body surface on one side were cut out from the sintered body, and the heat cycle was performed 100 times under the same conditions as in the first example. No peeling of the yttrium aluminum garnet layer was observed.

  That is, in the ceramic member, the dense yttrium aluminum garnet layer and the alumina base material are integrated through a portion in which the amount of yttrium aluminum garnet is inclined from the inside to the surface in the alumina base material. As a result, excellent heat cycle resistance was exhibited.

Fourth Example An appropriate amount of ion-exchanged water and 2 parts by weight of polyvinyl alcohol were added to a composition system containing 750 ppm of MgSO ₄ · 7H ₂ O in terms of magnesia with respect to 100 parts by weight of alumina particles having an average particle diameter of 0.3 μm. The slurry was prepared by stirring and mixing. This slurry was granulated with a spray dryer, and the resulting granulated powder was molded with a hydrostatic pressure press (CIP) at a pressure of 10 MPa to obtain a molded body having a thickness of 10 mm, a width of 100 mm, and a length of 100 mm. On the other hand, with respect to 100 parts by weight of yttrium aluminum garnet powder having an average particle diameter of 0.8 μm, an appropriate amount of ion-exchanged water is added to a composition system containing 0.5 parts by weight of ammonium polycarboxylate as a dispersant, and the mixture is stirred and mixed. A slurry was prepared.

  The slurry of the yttrium aluminum garnet was applied to the entire surface of the alumina compact and dried in a dryer at 40 ° C. Thereafter, the calcined body obtained by calcining at a temperature of 900 ° C. was calcined at a temperature of 1790 ° C. in a hydrogen gas atmosphere to obtain a ceramic member.

  As a result of identifying the ceramic member by X-ray diffraction (XRD), yttrium aluminum garnet was not present in addition to alumina on the surface and inside of the sintered body (ceramic member). That is, when the cross section of the ceramic member was observed and imaged with an electron microscope, it was confirmed that the ceramic member was an alumina-based ceramic member whose entire surface was covered with an yttrium aluminum garnet layer having a thickness of 20 to 30 μm.

  Further, when the average particle diameter of the alumina crystal particles was measured by the planimetric method using the inverted electron image, it was 20 μm. The inside (center part) of the base material was cut out and ICP emission analysis was performed to measure the amount of yttrium aluminum garnet, which was 0% by weight.

When a 10 × 10 mm square test piece was cut out from the sintered body and the fracture toughness was measured by the IF method using a Vickers indenter, it was 4.1 MPa · m ^1/2 and the fracture toughness of the alumina sintered body. The value was comparable to the value. Further, when the three-point bending strength of this sintered body was measured, it showed a value of 360 MPa.

  Moreover, when a plasma exposure test was performed under the same conditions as in the case of the first example, a test piece having a thickness of 2 mm and a 10 × 10 mm square each having a single-sided sintered body surface was cut out from the sintered body. The etching rate (nm / Hr) was 1 or less in all cases. Similarly, 10 test pieces each having a thickness of 2 mm and a 20 × 20 mm square each having a sintered body surface on one side are cut out from the sintered body and subjected to a heat cycle test under the same conditions as in the first embodiment. Local peeling of the yttrium aluminum garnet layer was confirmed before heat cycle 100 times 2 in 3 out of 10 pieces.

  It should be noted that a molded body or calcined body containing magnesium and yttria in an alumina granulated powder, and a yttrium aluminum garnet shaped body or calcined body is laminated on the surface of the molded body or calcined body to form hydrogen. A ceramic member having the same characteristics can be obtained even when sintered in an atmosphere containing. Moreover, the ceramic member which concerns on the 1st and 2nd Example, ie, the sintered compact which provided the yttrium aluminum garnet layer in the alumina-type base material surface, is made into the base material, The powder layer of the yttrium aluminum garnet is formed in the base material surface. Similarly, a ceramic member having the required characteristics can be obtained by laminating the formed body or calcined body again and sintering in an atmosphere containing hydrogen.

Comparative Examples 1 and 2
In the case of the first embodiment, alumina particles having an average particle size of 2.0 μm are used instead of alumina particles having an average particle size of 0.3 μm, and the calcining temperature of the calcined body is set to 1760 ° C. (Comparative Example 1). In addition, Y (CH ₃ COO) ₃ .4H ₂ O is 20 parts by weight instead of 1.5 parts by weight in terms of yttria, and the calcining temperature of the calcined body is 1770 ° C. (Comparative Example 2) Prepared two types of ceramic members under the same conditions as in the first embodiment.

  For these ceramic members, under the same conditions as in the first embodiment, the properties and thickness of the yttrium aluminum garnet layer formed on the alumina base material surface, identification by X-ray diffraction (XRD), alumina crystal particles Average particle size measurement, confirmation of change in the amount of yttrium aluminum garnet from the inside of the alumina base material (downward) to the surface (upper side), measurement of the amount of yttrium aluminum garnet inside the base material (center), fracture toughness value Tests such as three-point bending strength, plasma exposure test, and heat cycle were conducted.

In the case of Comparative Example 1, the yttrium aluminum garnet layer is not uniformly formed on the surface, the exposed portion of the alumina crystal particles is about 60% in area ratio, the average particle size of the alumina crystal particles is 3 μm, the inside of the base material (Center) Yttrium aluminum garnet amount 1% by weight, Confirmation of slant change in yttrium aluminum garnet amount from the inside of the alumina base material to the surface, Fracture toughness value 3.5 MPa · m ^1/2 , Three-point bending It was confirmed that portions having an intensity of 350 MPa and an etching rate (nm / Hr) of 10 by plasma exposure were locally scattered, and heat cycle measurement was impossible.

On the other hand, in the case of Comparative Example 2, the thickness of the yttrium aluminum garnet layer is 80 to 120 μm on the surface, the average particle diameter of alumina crystal particles is 20 μm, the amount of yttrium aluminum garnet in the base material (center part) is 8% by weight, and the alumina type Confirmation of gradient change of yttrium aluminum garnet amount from the inside of the substrate to the surface, fracture toughness value 3 MPa · m ^1/2 , three-point bending strength 280 MPa, etching rate (nm / Hr) 1 or less by plasma exposure, heat Cleared 100 cycles.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the alumina-based substrate may be a sintered body made of only alumina, and further, the kind of the sintering aid, the composition ratio of these additive components, etc. are appropriately determined according to the use / purpose of use of the ceramic member. You may choose.

According to the above method, a ceramic member having excellent mechanical properties such as bending strength and fracture toughness and excellent plasma resistance can be provided with high yield and mass production suitable for a semiconductor manufacturing apparatus.

The reflection electron image figure which shows the structure | tissue and state of the cut surface of the plasma-resistant member which concerns on an Example. Sectional drawing which shows schematic structure of a CVD apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Processing chamber 2 ... Antenna 3 ... Electromagnet 4 ... Permanent magnet 5 ... Etching gas supply port 6 ... Vacuum exhaust port 7 ... Semiconductor wafer 8 ... Lower electrode 9 ... First matching network 10 …… First high frequency power supply 11 …… Second matching network 12 …… Second high frequency power supply

Claims (6)

  A ceramic member comprising a base material substantially made of an alumina sintered body and an yttrium aluminum garnet layer having a thickness of 2 μm or more formed on the surface of the base material.   2. The ceramic member according to claim 1, wherein the substrate surface is coated with an yttrium aluminum garnet layer so that the alumina crystal particles in the alumina sintered body are not exposed.   The ceramic member according to claim 1 or 2, wherein a thickness of the yttrium aluminum garnet layer is 150 µm or less.   The ceramic member according to any one of claims 1 to 3, wherein the substrate is an alumina sintered body in which the amount of yttrium aluminum garnet increases in a gradient from the inside toward the surface.   The ceramic member according to any one of claims 1 to 4, wherein an amount of yttrium aluminum garnet in the alumina sintered body is 5% by weight or less. The ceramic member according to any one of claims 1 to 5, wherein the average crystal grain size of the alumina crystal particles in the alumina sintered body is 200 µm or less.

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