JP7531316B2 - Manufacturing method of SiC sintered member - Google Patents

Description

The present invention relates to a method for manufacturing SiC sintered components.

In semiconductor manufacturing equipment, the base used as a mounting platform for a ceramic electrostatic chuck or the like that holds a substrate such as a wafer on its surface is heated together with the electrostatic chuck, so it is preferable that the thermal expansion coefficient be similar to that of the electrostatic chuck, and that high-frequency power may be applied to the base, so that the base is made of a material with a low volume resistivity. One such material is sintered SiC.

However, since the sintering temperature for SiC sintered bodies is high and they are difficult to process, bases made of SiC sintered bodies have not yet been put to practical use.

Patent Document 1 discloses a technique for integrating ceramic calcined bodies by firing them under normal pressure and load at a temperature higher than the normal firing temperature. However, it only gives examples of integrating alumina calcined bodies and mullite calcined bodies under a load with a weight placed on them, and does not give examples of integrating SiC calcined bodies.

Patent Document 2 also discloses a technique for obtaining ceramic sintered bodies of different thicknesses by hot-pressing two sintered bodies. The sintered bodies are said to include ceramic powder, ceramic molded bodies, ceramic degreased bodies, and ceramic sintered bodies. However, only examples using aluminum nitride powder are given, and no examples using SiC calcined bodies are given.

Japanese Patent Application Publication No. 6-298574 JP 2000-141336 A

However, the techniques described in Patent Documents 1 and 2 above have the problem that, in reality, it is not possible to integrate SiC calcined bodies by sintering them together. When integrating SiC sintered bodies by diffusion bonding, since SiC sintered bodies are difficult to process, it takes a lot of time to polish or grind the bonding surfaces. Furthermore, when SiC molded bodies or SiC degreased bodies are integrated by sintering them together, the recesses formed in them deform during sintering, making it impossible to obtain a hollow structure with high dimensional accuracy.

The present invention was made in consideration of these circumstances, and aims to provide a method for manufacturing SiC sintered components that can produce SiC sintered components with hollow structures with high dimensional accuracy in a short period of time.

The first method for producing a SiC sintered member of the present invention includes the steps of calcining a first SiC molded body at a temperature of 1200°C or more and 1900°C or less to obtain a first SiC calcined body, calcining a second SiC molded body at a temperature of 1200°C or more and 1900°C or less to obtain a second SiC calcined body, forming a first plane on the first SiC calcined body, forming a second plane on the second SiC calcined body, forming a recess on at least one of the first plane or the second plane, stacking the first SiC calcined body and the second SiC calcined body with the first plane and the second plane in contact with each other, and firing the stacked first SiC calcined body and the second SiC calcined body at 2000°C or more and 2200°C or less while applying a pressure of 10 kgf/cm2 or ^more in the stacking direction.

The second method for producing a SiC sintered member of the present invention includes the steps of calcining a first SiC molded body at a temperature of 1200° C. or more and 1900° C. or less to obtain a first SiC calcined body, calcining a second SiC molded body at a temperature of 1200° C. or more and 1900° C. or less to obtain a second SiC calcined body, forming a first flat surface on the first SiC calcined body, forming a second flat surface on the second SiC calcined body, and forming a recess on at least one of the first flat surface or the second flat surface. The method includes the steps of: forming, on at least one of the first plane or the second plane, a Si sprayed film obtained by thermal spraying, or a bonding material made of silicon powder or SiC powder obtained by heat-treating a paste; stacking the first SiC calcined body and the second SiC calcined body in a state in which the first plane and the second plane are in contact with each other via the bonding material; and firing the stacked first SiC calcined body and the second SiC calcined body at 1900° C. or higher and 2200° C. or lower while applying a pressure of 0.005 kgf/ ^cm2 or higher in the stacking direction.

According to the first and second manufacturing methods of the present invention for producing a SiC sintered member, it is possible to obtain a SiC sintered member having a hollow structure derived from the recesses. The first and second planes and recesses are formed on the first and second SiC calcined bodies, and the grinding, polishing, and other operations required to form these can be performed in a shorter time than when these are formed on a SiC sintered body. In addition, it is possible to improve the dimensional accuracy of the hollow structure of the SiC sintered member derived from the recesses, compared to when SiC molded bodies with recesses are sintered together to form an integrated body.

Furthermore, according to the first manufacturing method of SiC sintered parts of the present invention, compared to the technology disclosed in Patent Document 1 above, in which sintering is performed under a small load applied using a weight, sintering is performed while applying a pressure of 10 kgf/ ^cm2 (=0.98 MPa) or more, which makes it possible to improve the bonding strength and densify the SiC sintered parts.

In the first method for producing a SiC sintered member of the present invention, it is preferable that a sintering aid containing boron is interposed between the first plane and the second plane in the stacking step.

In this case, since the sintering aid is present on the bonding surface, sintering in the vicinity of the bonding surface is promoted, and it is possible to improve the bonding strength.
A third method for producing a SiC sintered member of the present invention includes a step of calcining a first SiC molded body at a temperature of 1200° C. or more and 1900° C. or less to obtain a first SiC calcined body, a step of calcining a second SiC molded body at a temperature of 1200° C. or more and 1900° C. or less to obtain a second SiC calcined body, a step of calcining a third SiC molded body at a temperature of 1200° C. or more and 1900° C. or less to obtain a third SiC calcined body, a step of forming a first plane on the first SiC calcined body, a step of forming a second plane on the second SiC calcined body, and The method includes the steps of: forming a recess in at least one of the first plane or the second plane; stacking the first SiC calcined body and the second SiC calcined body in a state in which the first plane and the second plane are in contact with each other via a bonding material; and stacking the third SiC calcined body on the outside of the first SiC calcined body or the second SiC calcined body in the stacking direction via a release material; and firing the stacked first SiC calcined body, the second SiC calcined body, and the third SiC calcined body at 1900° C. or higher and 2200° C. or lower while applying a pressure of 0.005 kgf/cm2 or higher in the stacking direction to the stacked first SiC calcined body, the second SiC calcined body, and the third SiC calcined ^body .
According to the third method for producing a SiC sintered member of the present invention, by applying pressure to the stepped or recessed portion of the first or second SiC calcined body while the third SiC calcined body is placed through a release material, the third SiC calcined body shrinks in the same manner as the first and second SiC calcined bodies during firing, making it possible to uniformize the pressure applied during firing and improve the bonding strength. In addition, after firing, the sintered body portion corresponding to the third SiC calcined body can be easily peeled off, making it unnecessary to remove it by machining or the like.

In the third method for producing a SiC sintered member of the present invention, for example, the bonding material is any one of silicon powder, SiC powder, and a Si thermal sprayed film.

In addition, in the first to third methods for manufacturing a SiC sintered member of the present invention, it is preferable to include a step of storing the first SiC calcined body and the second SiC calcined body prior to the step of forming the recess.

In this case, by storing the first and second SiC calcined bodies prepared in advance, it is possible to obtain a SiC sintered member in a time that is at least shorter than the time required for calcination. In addition, by storing the first and second SiC calcined bodies on which the first and second planes are formed, it is possible to obtain a SiC sintered member in a time that is also shorter than the time required for the process of forming the first and second planes.

In addition, the first and second manufacturing methods of the SiC sintered member of the present invention further include a step of calcining the third SiC compact at a temperature of 1200°C or more and 1900°C or less to obtain a third SiC calcined body, and in the stacking step, the third SiC calcined body is stacked on the outer side of the stacking direction of the first SiC calcined body or the second SiC calcined body via a release material, and in the firing step, the pressure is preferably applied to the stacked first SiC calcined body, the second SiC calcined body, and the third SiC calcined body.

In this case, by applying pressure to the stepped or recessed portion of the first or second SiC calcined body while the third SiC calcined body is placed via a release material, the third SiC calcined body shrinks in the same manner as the first and second SiC calcined bodies during firing, making it possible to equalize the pressure applied during firing and improve the bonding strength. In addition, after firing, the sintered body portion corresponding to the third SiC calcined body can be easily peeled off, making it unnecessary to remove it by machining or the like.

In the first to third methods for manufacturing a SiC sintered member of the present invention, it is preferable that at least one of the first flat surface, the second flat surface and the recessed portion is formed by dry grinding or polishing.

In this case, compared to wet grinding or polishing, the grinding or polishing fluid penetrates into the first or second SiC calcined body, eliminating the risk of impurities remaining in the SiC sintered component.

1 is a flowchart showing a method for manufacturing a SiC sintered member according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing first and second SiC calcined bodies. FIG. 3 is a schematic cross-sectional view showing a state in which the first and second SiC calcined bodies are stacked. FIG. 3 is a schematic cross-sectional view showing a SiC sintered member. 5 is a flowchart showing a method for manufacturing a SiC sintered member according to a second embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing first to third calcined SiC bodies. FIG. 2 is a schematic cross-sectional view showing a state in which first to third calcined SiC bodies are stacked. FIG. 3 is a schematic cross-sectional view showing a SiC sintered member. FIG. 13 is a schematic cross-sectional view showing the first and second SiC calcined bodies in Examples 8, 9, and 11. FIG. 3 is a schematic cross-sectional view showing a state in which the first and second SiC calcined bodies are stacked. FIG. 3 is a schematic cross-sectional view showing a SiC sintered member. 10 is a flowchart showing a method for manufacturing a SiC sintered member according to a third embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing the first and second SiC calcined bodies and a bonding material. FIG. 4 is a schematic cross-sectional view showing a state in which the first and second SiC calcined bodies and the bonding material are stacked. FIG. 3 is a schematic cross-sectional view showing a SiC sintered member. 10 is a flowchart showing a method for manufacturing a SiC sintered member according to a fourth embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing first to third calcined SiC bodies and a bonding material. FIG. 2 is a schematic cross-sectional view showing a state in which the first to third calcined SiC bodies and bonding materials are stacked. FIG. 3 is a schematic cross-sectional view showing a SiC sintered member.

The manufacturing method of the SiC sintered part 10 according to the first embodiment of the present invention will be described with reference to the drawings. Note that the drawings are deformed to clearly show the SiC sintered part 10 and its components, and do not represent the actual proportions, and the directions such as up and down are merely examples.

As shown in FIG. 1, the method for manufacturing a SiC sintered member 10 according to the first embodiment of the present invention includes a first SiC calcined body obtaining step STEP 1, a second SiC calcined body obtaining step STEP 2, a first plane forming step STEP 3, a second plane forming step STEP 4, a recess forming step STEP 5, a stacking step STEP 6, and a firing step STEP 7.

In the first SiC calcined body obtaining step STEP1, referring to FIG. 2A, the first SiC molded body is calcined at a temperature of 1200°C or more and 1900°C or less to obtain the first SiC calcined body 1. In the second SiC calcined body obtaining step STEP2, the second SiC molded body is calcined at a temperature of 1200°C or more and 1900°C or less to obtain the second SiC calcined body 2. The calcination temperatures in the first SiC calcined body obtaining step STEP1 and the second SiC calcined body obtaining step STEP2 may be the same or different.

In the first SiC calcined body obtaining step STEP 1 and the second SiC calcined body obtaining step STEP 2, two SiC molded bodies formed from SiC (silicon carbide) powder are calcined to form the first and second SiC calcined bodies 1 and 2. For example, additives such as a sintering aid and a thermosetting resin binder are appropriately added to and mixed with the SiC powder to prepare a molding raw material, and this molding material is used for pressure molding to form two SiC molded bodies.

The SiC powder is preferably of high purity, preferably 96% or more, more preferably 98% or more. The average particle size of the SiC powder is preferably 0.1 μm or more and 1.0 μm or less, more preferably 0.3 μm or more and 0.8 μm or less.

The mixing method may be either wet or dry, and a mixer such as a ball mill or a vibration mill may be used. Alternatively, a sintering aid may be added to the SiC powder to produce SiC granules, and an additive such as a thermosetting resin binder may be added to the SiC granules, which are then pressure molded to form a SiC molded body. As a molding method, for example, a known method such as uniaxial pressing or cold isostatic pressing (CIP) may be used.

The SiC molded body may be heated at a temperature of 900°C or more and less than 1200°C to obtain a SiC degreased body, and then this SiC degreased body may be heated at a temperature of 1200°C or more and 1900°C or less to obtain the first and second SiC calcined bodies 1, 2. The SiC molded body may also be heated while being continuously heated to a temperature of 1200°C or more and 1900°C or less to obtain the first and second SiC calcined bodies 1, 2.

In the first plane formation step STEP 3, a first plane 1a is formed on the first SiC calcined body 1. In the second plane formation step STEP 4, a second plane 2a is formed on the second SiC calcined body 2. The first plane 1a and the second plane 2a become the surfaces that come into contact in the stacking step STEP 6.

The first and second planes 1a and 2a are formed by polishing or grinding using a surface grinding machine or lapping machine such as an NC lathe or MC processing machine so that the surface roughness Ra is preferably 0.15 μm or more and 0.8 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

In the recess formation step STEP 5, the recess 3 is formed in at least one of the first plane 1a or the second plane 2a. The recess 3 is formed by a grinding process or the like so as to be dug into either the first plane 1a or the second plane 2a, or both.

In the first plane forming step STEP 3 or the second plane forming step STEP 4, the first or second plane 1a, 2a may not be polished or may only be roughly ground, and after the recess 3 is formed in the recess forming step STEP 5, the first or second plane 1a, 2a may be polished or subjected to finish grinding.

When the recesses 3 are formed by carving from both the first and second planes 1a, 2a, these recesses 3 may be integrated when the first and second planes 1a, 2a are brought into contact in the lamination process STEP 5, or may be closed by another plane. In addition, it is preferable to perform chamfering such as R-surface or C-surface on the boundary parts between the first and second planes 1a, 2a and the recesses 3 and the bottom corner parts of the recesses 3.

In addition, in the first plane forming step STEP 3, the second plane forming step STEP 4, or the recess forming step STEP 5, it is preferable to form the first plane 1a, the second plane 2a, or the recess 3 by dry grinding or polishing. This makes it possible to eliminate the risk of impurities remaining in the SiC sintered member 10 due to the infiltration of the grinding fluid or polishing fluid into the inside of the first or second calcined body 1, 2. When performing grinding and polishing, it is preferable to perform both of these processes by dry methods.

Furthermore, a storage step of storing the first and second SiC calcined bodies 1, 2 may be provided before the recess formation step STEP 5. In this way, by storing the first and second SiC calcined bodies 1, 2 prepared in advance, it is possible to obtain the SiC sintered member 10 in a time that is at least shorter than the time required for calcination. In addition, by storing the first and second SiC calcined bodies 1, 2 after the first plane formation step STEP 3 and the second plane formation step STEP 4, it is possible to obtain the SiC sintered member 10 in a time that is also shorter than the time required for the steps of forming the first plane 1a and the second plane 2a.

In the stacking step STEP 6, referring to FIG. 2B, the first SiC calcined body 1 and the second SiC calcined body 2 are stacked with the first plane 1a and the second plane 2a in contact with each other.

In addition, in the lamination step STEP 6, it is preferable to interpose a sintering aid containing boron between the first plane 1a and the second plane 2a. This allows the sintering aid to be present on the first and second planes 1a, 2a that will become the bonding surfaces in the firing step STEP 7, promoting sintering near the bonding surfaces 1a, 2a and improving the bonding strength. For example, an aqueous solution of boric acid can be used as a sintering aid containing boron.

In addition, in the lamination step STEP 6, it is also preferable to perform lamination with a core (not shown) inserted in the recess 3. The core is, for example, a resin body that follows the shape of the recess 3, but it may also be a large number of tiny resin bodies that fill the recess 3. However, it is preferable that the core does not cause undesirable deformation of the recess 3 against the pressure applied in the firing step STEP 7.

In the firing step STEP 7, the stacked first and second SiC calcined bodies 1 and 2 are fired at 2000° C. to 2200° C. while applying a pressure of 10 kgf/cm ² or more in the stacking direction. As a result, referring to FIG. 2C , the first and second SiC calcined bodies 1 and 2 are sintered and integrated to obtain a SiC sintered member 10.

In the firing step STEP 7, pressure sintering is performed by hot pressing, which heats the material while applying pressure at least in the stacking direction. The heating time is preferably 0.1 to 10 hours, more preferably 1 to 5 hours. The firing atmosphere is, for example, an inert gas atmosphere, but may also be a vacuum atmosphere.

If a core is inserted into the recess 3 in the lamination step STEP 6, the core can be removed in or after the firing step STEP 7. For example, if the recess 3 is connected to the outside, the melted core can be discharged to the outside.

When integrating SiC sintered bodies by diffusion bonding, since the SiC sintered bodies are difficult to process, a great deal of time is required to polish the bonding surfaces. In comparison, in the manufacturing method for the SiC sintered member 10 according to the first embodiment of the present invention described above, it is possible to reduce the time required to grind or polish the first and second flat surfaces 1a, 2a and the recesses 3 of the first and second calcined bodies 1, 2. In addition, compared to integrating SiC molded bodies with recesses 3 by firing them, it is possible to improve the dimensional accuracy of the hollow structure of the SiC sintered member 10 resulting from the recesses 3.

Furthermore, compared to the technique disclosed in Patent Document 1, in which firing is performed under a small load using a weight, firing is performed while applying a pressure of 10 kgf/cm2 or ^more , which makes it possible to improve the bonding strength and densify the SiC sintered member 10. Note that a pressure of less than 10 kgf/ ^cm2 is inappropriate because good surface contact between the first and second flat surfaces 1a, 2a of the first and second calcined bodies 1, 2 cannot be obtained during firing, which causes poor bonding.

Next, a method for manufacturing a SiC sintered member 20 according to a second embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 3, the method for manufacturing a SiC sintered member 20 according to the second embodiment of the present invention includes a first SiC calcined body obtaining step STEP 11, a second SiC calcined body obtaining step STEP 12, a third SiC calcined body obtaining step STEP 13, a first plane forming step STEP 14, a second plane forming step STEP 15, a recess forming step STEP 16, a stacking step STEP 17, and a firing step STEP 18.

In the first SiC calcined body obtaining step STEP 11 in FIG. 3, referring to FIG. 4A, the first SiC molded body is calcined at a temperature of 1200°C or more and 1900°C or less to obtain the first SiC calcined body 11. In the second SiC calcined body obtaining step STEP 12, the second SiC molded body is calcined at a temperature of 1200°C or more and 1900°C or less to obtain the second SiC calcined body 12. Note that the calcination temperatures in the first SiC calcined body obtaining step STEP 11 and the second SiC calcined body obtaining step STEP 12 may be the same or different.

The first SiC calcined body obtaining process STEP 11 is similar to the first SiC calcined body obtaining process STEP 1 in FIG. 1 described above, and the second SiC calcined body obtaining process STEP 12 is similar to the second SiC calcined body obtaining process STEP 2 described above, so the explanation is omitted.

In the third SiC calcined body obtaining step STEP 13, the third SiC molded body is calcined at a temperature of 1200°C or more and 1900°C or less to obtain the third SiC calcined body 13. The third SiC calcined body 13 may be obtained in the same manner as the first or second SiC calcined body 11, 12 described above. The calcination temperature in the third SiC calcined body obtaining step 13 may be the same as or different from the calcination temperature in the first or second SiC calcined body obtaining step STEP 11, 12.

The third SiC calcined body 13 is configured in a shape that eliminates steps and recesses on the outside in the stacking direction when the first SiC calcined body 11 and the second SiC calcined body 12 are stacked in the stacking process STEP 17 with the first plane 11a and the second plane 21a in contact with each other, as shown in FIG. 4B. For example, if a ring-shaped step is formed on the outer periphery of the surface on the outside in the stacking direction of the second calcined body 12, the third SiC calcined body 13 is formed as a ring-shaped member having a thickness that is approximately equal to the height of the step.

Next, in the first plane formation step STEP 14, a first plane 11a is formed on the first SiC calcined body 11. In the second plane formation step STEP 15, a second plane 12a is formed on the second SiC calcined body 12.

The first plane forming process STEP 14 is similar to the first plane forming process STEP 3 described above, and the second plane forming process STEP 15 is similar to the second plane forming process STEP 4 described above, so their explanations are omitted.

Next, in the recess formation process STEP 16, a recess 14 is formed in at least one of the first plane 11a or the second plane 12a. The recess formation process STEP 16 is similar to the recess formation process STEP 5 described above, so a description thereof is omitted.

Next, in the stacking step STEP 17, referring to FIG. 4B, the first SiC calcined body 11 and the second SiC calcined body 12 are stacked with the first plane 11a and the second plane 12a in contact with each other.

Furthermore, in the stacking step 17, the third SiC calcined body 13 is stacked on the outer side of the first SiC calcined body 11 or the second SiC calcined body 12 in the stacking direction via a release material 15. As a result, the first to third SiC calcined bodies 11 to 13 are stacked in a flat shape with no steps or recesses on the outer side in the stacking direction. For example, a carbon sheet or a boron nitride sheet can be used as the release material 15. Carbon or boron nitride can also be directly coated on the first SiC calcined body 11 or the second SiC calcined body 12.

Next, in the firing step STEP 18, the stacked first to third SiC calcined bodies 11 to 13 are fired at 2000°C to 2200°C while applying a pressure of 1 MPa or more in the stacking direction. Since the firing step STEP 18 is similar to the firing step STEP 7 described above, a description thereof will be omitted.

Upon completion of the firing step STEP 18, as shown in FIG. 4C, the first and second SiC calcined bodies 11, 12 are sintered and integrated to obtain the SiC sintered member 20. Note that the SiC sintered body (not shown) formed by sintering the third SiC calcined body 13 is only in contact with the SiC sintered member 20 via the release material 15, and is therefore not sintered with the SiC sintered member 20 and can be easily separated from the SiC sintered member 20.

The method for manufacturing the SiC sintered member 20 according to the second embodiment of the present invention described above also has the same effects as the method for manufacturing the SiC sintered member 10 according to the first embodiment of the present invention described above.

Furthermore, in the manufacturing method of the SiC sintered member 20 according to the second embodiment of the present invention, the third SiC calcined body 13 is placed in a step or recess on the outer side of the stacking direction of the first or second SiC calcined body 11, 12 via a release material 15 and then pressurized and fired. During this firing, the third SiC calcined body 13 shrinks in the same way as the first and second SiC calcined bodies 11, 12. This makes it possible to uniform the pressure applied to the first and second SiC calcined bodies 11, 12 during firing and to improve the bonding strength.

Next, a method for manufacturing a SiC sintered member 10 according to a third embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 6, the manufacturing method of the SiC sintered member 10 according to the third embodiment of the present invention includes a first SiC calcined body obtaining process STEP 1, a second SiC calcined body obtaining process STEP 2, a first plane forming process STEP 3, a second plane forming process STEP 4, a recess forming process STEP 5, a bonding material forming process STEP 5-1, a stacking process STEP 6, and a firing process STEP 7.

The first SiC calcined body obtaining process STEP 1, the second SiC calcined body obtaining process STEP 2, the first plane forming process STEP 3, the second plane forming process STEP 4, the recess forming process STEP 5, and the firing process STEP 7 are similar to the steps STEP 1 to STEP 5 and STEP 6 described in the manufacturing method for the SiC sintered member 10 according to the first embodiment of the present invention, and therefore will not be described here.

In the bonding material forming step STEP5-1, a bonding material 6 is formed between the first plane 1a and the second plane 2a. The bonding material 6 contains Si (silicon) or SiC. Methods for forming such a bonding material 6 include a conventionally known wet method in which powder is made into a paste and printed and applied to a plane, and dry methods such as plasma spraying, arc spraying, RF plasma spraying, electromagnetic acceleration plasma spraying, wire explosion spraying, electrothermal explosion powder spraying, flame spraying such as wire flame spraying, powder flame spraying, and rod flame spraying, high velocity flame spraying (HVOF, HVAF), laser spraying, laser-plasma composite spraying, and cold spraying. The spraying raw material may be, for example, granules with an average particle size of 20 μm to 60 μm, or a slurry containing particles with an average particle size of 0.5 μm to 6 μm.

As a result, the bonding material 6 is interposed between the first and second surfaces 1a, 2a that will become the bonding surfaces in the firing process STEP 7, which promotes sintering near the bonding surfaces 1a, 2a and makes it possible to improve the bonding strength.

When the joining material 6 is formed by thermal spraying, for example, metal Si powder having a volumetric median diameter (D50) of 0.5 to 6 μm is thermally sprayed onto the first plane 1a, the second plane 2a, or both planes 1a, 2a using a plasma thermal spraying device, a high velocity oxygen flame (HVOF) thermal spraying device, or the like, to form a Si thermal sprayed film.

When the bonding material 6 is formed using a paste, for example, a Si paste or a SiC paste is prepared by adding metal Si powder or SiC powder having an average particle size of 0.1 to 3 μm, a binder, and an organic vehicle containing a plasticizer, and this paste is applied, printed, sprayed, etc. to the first plane 1a, the second plane 2a, or both of these planes 1a, 2a, and then heat-treated in an air atmosphere or a nitrogen atmosphere at 200°C or higher and lower than 800°C for 0.1 to 5 hours to form the bonding material 6 made of Si powder or SiC powder, etc.

In the stacking step STEP 6, referring to FIG. 7B, the first SiC calcined body 1 and the second SiC calcined body 2 are stacked with the first plane 1a and the second plane 2a in contact with each other via the bonding material 6.

In the firing step STEP 7, the stacked first and second SiC calcined bodies 1 and 2 and the bonding material 6 are fired at 1900° C. to 2200° C. while applying a pressure of 0.005 kgf/cm ² (=490 Pa) or more in the stacking direction. As a result, referring to Fig. 7C, the first and second SiC calcined bodies 1 and 2 are sintered and integrated to obtain a SiC sintered member 10.

In the firing step STEP 7, sintering is performed by normal pressure firing with a load applied at least in the stacking direction, or by hot pressing in which heating is performed under pressure. The heating time is preferably 0.1 to 10 hours, more preferably 1 to 5 hours. The firing atmosphere is, for example, an inert gas atmosphere, but may also be a vacuum atmosphere.

When SiC sintered bodies are joined together to form an integrated body, it takes a long time to polish the joining surfaces because the SiC sintered bodies are difficult to process. In comparison, in the manufacturing method for the SiC sintered member 10 according to the third embodiment of the present invention described above, it is possible to reduce the time required to grind or polish the first and second flat surfaces 1a, 2a and the recesses 3 of the first and second calcined bodies 1, 2. In addition, it is possible to improve the dimensional accuracy of the hollow structure of the SiC sintered member 10 resulting from the recesses 3, compared to when SiC molded bodies with the recesses 3 are sintered together to form an integrated body.

In addition, since the first and second calcined bodies 1 and 2 can be integrated by firing them via the bonding material 6, the pressure applied in the firing process STEP 7 can be small, which reduces equipment constraints and contributes to lower costs.

It should be noted that a pressure of less than 0.005 kgf/ ^cm2 is inappropriate because good surface contact between the first and second flat surfaces 1a, 2a of the first and second calcined bodies 1, 2 is not obtained during firing, causing poor bonding. It is also preferable to perform firing while applying a pressure of 1 kgf/cm2 or ^more using a hot press machine or the like, because this provides even better bonding of the bonding surfaces.

Next, a method for manufacturing a SiC sintered member 20 according to a fourth embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 8, the manufacturing method of the SiC sintered member 20 according to the fourth embodiment of the present invention includes a first SiC calcined body obtaining process STEP 11, a second SiC calcined body obtaining process STEP 12, a third SiC calcined body obtaining process STEP 13, a first plane forming process STEP 14, a second plane forming process STEP 15, a recess forming process STEP 16, a bonding material forming process STEP 16-1, a stacking process STEP 17, and a firing process STEP 18.

The first SiC calcined body obtaining step STEP 11, the second SiC calcined body obtaining step STEP 12, the third SiC calcined body obtaining step STEP 13, the first plane forming step STEP 14, the second plane forming step STEP 15, and the recess forming step STEP 16 are similar to steps STEP 11 to STEP 15, 16 described in the manufacturing method for SiC sintered member 20 according to the second embodiment of the present invention, and therefore their explanations are omitted. In addition, the bonding material forming step STEP 16-1 and the firing step STEP 18 are similar to steps STEP 5-1, 7 described in the manufacturing method for SiC sintered member 10 according to the third embodiment of the present invention, and therefore their explanations are omitted.

The method for manufacturing a SiC sintered member 20 according to the fourth embodiment of the present invention described above also has the same effects as the method for manufacturing a SiC sintered member 20 according to the second embodiment of the present invention described above.

The present invention is not limited to the manufacturing method of the SiC sintered members 10, 20 specifically described in the first to fourth embodiments above, and can be modified as appropriate within the scope of the claims. For example, the SiC sintered members 10, 20 are formed by integrating two SiC calcined bodies 1, 2 or 11, 12, but may be formed by integrating three or more SiC calcined bodies.

(Examples 1 to 7)
In Examples 1 to 7, in the first and second SiC calcined body obtaining steps STEP 1 and 2, first, a raw material powder was prepared by adding 0.1 to 0.5 mass % of _B4C as a sintering aid, C (carbon), a binder such as PVA as a molding aid, etc. to SiC powder with a purity of 98% and an average particle size of 0.5 μm. Next, this raw material powder was granulated with a spray dryer to obtain granules.

The granules were then filled into a metal mold and uniaxially pressed at a pressure of 20 MPa to obtain two SiC compacts. The bulk density of these SiC compacts was as shown in Table 1. Next, these SiC compacts were fired in a firing furnace in an argon atmosphere at a furnace temperature of 1200°C to 1900°C for three hours to obtain two calcined SiC bodies. The bulk density after calcination and the shrinkage rate due to calcination were as shown in Table 1.

Next, in the first and second plane forming steps STEP 3 and 4, the two SiC calcined bodies were processed into the first and second SiC calcined bodies 1 and 2 in the shape of square plates with sides of 100 mm and heights of 10 mm, as shown in FIG. 2A. The first plane 1a of the first SiC calcined body 1 and the second plane 2a of the second SiC calcined body 2 were ground using a grindstone equipped with diamond abrasive grains of #170 in Examples 1 to 4, 6, and 7. In Example 5, the grindstone was ground using a grindstone equipped with diamond abrasive grains of #600. The grinding was performed dry, without using an abrasive liquid. The average arithmetic mean roughness (Ra) and maximum height (Rz) of the first and second planes 1a and 2a were as shown in Table 1.

Next, in the recess formation step STEP 5, recesses 3 were formed on the second flat surface 2a of the second SiC calcined body 2. The recesses 3 were three linear grooves, each 20 mm wide, 5 mm deep, and 70 mm long. The recesses 3 were formed by MC processing using an end mill with a diameter of 20 mm. The evaluation of the workability of this MC processing is shown in Table 1.

The evaluation was based on the load on the spindle during processing, chatter, and damage to the calcined body. In Table 1, the evaluation "◎" means that the cutting depth in one pass is 0.25 mm or more and the blade feed rate is 250 mm/min or more, which is excellent. The evaluation "◯" means that the cutting depth in one pass is 0.2 mm or more and the blade feed rate is 200 mm/min or more, which is good. The evaluation "△" means that the cutting depth in one pass is 0.15 mm or more and the blade feed rate is 150 mm/min or more, which is acceptable. The evaluation "×" means that the cutting depth in one pass is less than 0.15 mm or the blade feed rate is less than 150 mm/min, which is poor. The evaluation "XX" means that the calcined body was damaged during processing, which is poor.

As a result, it was found that, in terms of workability when forming the recesses 3, it is possible to form the recesses 3 if the calcination temperature is 1200°C or higher and 1900°C or lower, but it is better if it is 1250°C or higher and 1785°C or lower.

Next, in the stacking step STEP 6, referring to FIG. 2B, the first SiC calcined body 1 and the second SiC calcined body 2 were stacked with the first plane 1a and the second plane 2a in contact with each other.

Next, in the firing step STEP 7, the first and second SiC calcined bodies 1 and 2 thus stacked were sandwiched between carbon flat plates as press plates in an argon atmosphere in a firing furnace, and fired for 3 hours at a furnace temperature of 2070° C. while applying a load of 25 kgf/cm ² (=2.45 MPa) in the stacking direction in Examples 1 to 6 and a load of 10 kgf/cm ² (=0.98 MPa) in Example 7. As a result, a SiC sintered member 10 was obtained, as shown in FIG. 2C. The bulk density of the SiC sintered member 10 was as shown in Table 1.

Then, this SiC sintered component 10 was cut to include the joint, the cut surface was polished, and the joint was visually inspected by an experimenter using a magnifying glass or the like. As a result, no poor bonding or damage was found at the joint, and no damage or distortion was found in the hollow structure originating from the recess 3.

The results of Examples 1 to 7 are summarized in Table 1.

(Comparative Example 1)
In Comparative Example 1, a SiC molded body prepared in the same manner as in Examples 1 to 7 was sintered in a sintering furnace in an argon atmosphere at a furnace temperature of 2070° C. for 3 hours to obtain two SiC sintered bodies. That is, in Comparative Example 1, a SiC sintered body was used instead of the SiC calcined bodies 1 and 2. An attempt was made to form a recess 3 in the SiC sintered body by using the MC processing machine that formed the recess 3 in Examples 1 to 7, but this was very difficult and was abandoned midway.

(Comparative Example 2)
In Comparative Example 2, a SiC molded body prepared in the same manner as in Examples 1 to 7 was sintered in a sintering furnace in an argon atmosphere at a furnace temperature of 1100° C. for 3 hours to obtain two SiC calcined bodies. An attempt was made to form recesses 3 in the SiC calcined bodies by using the MC processing machine that formed the recesses 3 in Examples 1 to 7, but the calcined body was damaged during processing, so the attempt was abandoned midway.

(Comparative Example 3)
In Comparative Example 3, the SiC sintered member 30 was produced in the same manner as in Example 7, except that the load applied to the stacked first and second SiC calcined bodies 1 and 2 in the firing step STEP 7 was 5 kgf/ ^cm2 (=0.49 MPa). However, the density of the sintered body was reduced, and poor bonding was observed at the bonding portion of the SiC sintered member 30.

The results of Comparative Examples 1 to 3 are summarized in Table 2.

(Example 8)
In Example 8, as the first and second plane forming steps STEP3 and 4 in FIG. 1, two SiC calcined bodies were processed into a disk-shaped first SiC calcined body 21 having a diameter of 400 mm and a thickness of 10 mm and a disk-shaped second SiC calcined body 22 having a diameter of 400 mm and a thickness of 25 mm, as shown in FIG. 5A. The first plane 21a of the first SiC calcined body 21 and the second plane 22a of the second SiC calcined body 22 were ground using a grindstone equipped with diamond abrasive grains of #170. At this time, the grinding was performed in a dry manner without using an abrasive liquid. The average arithmetic mean roughness (Ra) and maximum height (Rz) of the first and second planes 21a and 22a were as shown in Table 2. In addition, as the recess forming step STEP5 in FIG. 1, recesses 23 and 24 were formed by MC processing similar to that in Example 1. The recess 23 was formed in a circumferential shape with a width of 20 mm and a depth of 5 mm on the second flat surface 22a of the second SiC calcined body 22 so that it could be used as a refrigerant flow path. The recess 24 was formed in an annular shape with a width of 25 mm and a depth of 15 mm on the outer periphery of the surface opposite to the second flat surface 22a of the second SiC calcined body 22. Except for these points, the SiC sintered member 30 was produced in the same manner as in Example 1.

As with Example 1, no poor bonding or damage was found at the joint of this SiC sintered member 30, and no damage or distortion was found in the hollow structure originating from the recess 23. The results of Example 8 are summarized in Table 2. It was confirmed that the SiC sintered member 30 produced in Example 8 can be used as a base for an electrostatic chuck.

Example 9
In Example 9, the first and second calcined SiC bodies 21, 22 were obtained in the same manner as in Example 8, except for the grinding method for the first and second flat surfaces 21a, 22a.

In more detail, the first and second SiC calcined bodies 21, 22 were ground using a grindstone equipped with #600 diamond abrasive grains, and the average arithmetic mean roughness (Ra) of the first and second flat surfaces 21a, 22a was set to 0.27 μm. Furthermore, another SiC sintered body having a flat surface with an arithmetic mean roughness (Ra) of 0.01 μm was used, and dry polishing was performed by sliding at a speed of 0.5 m/min while applying a load of 6000 Pa perpendicular to the surface direction. As a result, the average arithmetic mean roughness (Ra) of the first and second flat surfaces 21a, 21b was 0.18 μm.

Next, the lamination step STEP 6 and the firing step STEP 7 in FIG. 1 were carried out in the same manner as in Example 8. As a result, a SiC sintered member 30 was obtained.

As with Example 8, no poor bonding or damage was found in the bonded portion of this SiC sintered member 30, and no damage or distortion was found in the hollow structure resulting from the recess 23. The results of Example 9 are summarized in Table 3. It was confirmed that the SiC sintered member 30 produced in Example 9 can be used as a base for an electrostatic chuck.

Example 10
In Example 10, as the first and second SiC calcined body obtaining steps STEP 11 and STEP 12 in Fig. 3, two SiC molded bodies were obtained in the same manner as the first and second SiC calcined body obtaining steps STEP 1 and STEP 2 in Example 8. Next, these SiC molded bodies were sintered in a sintering furnace in an argon atmosphere at a furnace temperature of 1500°C for three hours to obtain two SiC calcined bodies.

In addition, as the third SiC calcined body obtaining step STEP 13, a SiC molded body was obtained in the same manner as the first and second SiC calcined body obtaining steps STEP 1 and 2 in Example 1. Next, this SiC molded body was sintered in a sintering furnace in an argon atmosphere at a furnace temperature of 1500°C for three hours to obtain one SiC calcined body.

Next, as the first and second plane forming steps STEP 14 and 15 in FIG. 3, referring to FIG. 4A, the two SiC calcined bodies were processed into a first SiC calcined body 11 having a disk shape with a diameter of 400 mm and a thickness of 10 mm and a second SiC calcined body 12 having a disk shape with a diameter of 400 mm and a thickness of 25 mm. The first plane 11a of the first SiC calcined body 11 and the second plane 12a of the second SiC calcined body 12 were ground using a grindstone equipped with diamond abrasive grains of #170. In addition, one SiC calcined body was processed into a third SiC calcined body 13 having an outer diameter of 400 mm, an inner diameter of 350.5 mm, and a thickness of 14.5 mm.

Next, in the recess formation step STEP 16, a recess 14 was formed on the second flat surface 12a of the second SiC calcined body 12, and a circular recess 25 mm wide and 15 mm deep was formed on the outer periphery of the surface opposite the second flat surface 12a of the second SiC calcined body 12. The recess 14 had a circumferential shape of 10 mm wide and 10 mm deep, corresponding to a flow path for a refrigerant. This recess 14 was formed by MC processing in the same manner as in Example 8.

Next, in the stacking step STEP 17, referring to FIG. 4B, the first SiC calcined body 11 and the second SiC calcined body 12 were stacked with the first plane 11a and the second plane 12a in contact with each other. Furthermore, the third SiC calcined body 13 was placed on the outer periphery of the second SiC calcined body 12 via a release material 15, and below the first plane 11a of the first SiC calcined body 11 via the release material 15. Note that the release material 15 was a carbon sheet having a thickness of 0.25 mm.

Next, in the firing step STEP 18, the first to third SiC calcined bodies 11 to 13 thus stacked were fired in the same manner as in the firing step STEP 7 of Example 1. Thereafter, the fired portion of the third SiC calcined body 13 was peeled off to obtain the SiC sintered member 20, as shown in FIG. 4C.

Then, this SiC sintered member 20 was cut to include the joint, the cut surface was polished, and the joint was visually inspected by an experimenter using a magnifying glass or the like. As a result, no poor bonding or damage was found at the joint, and no damage or distortion was found in the hollow structure originating from the recess 14.

(Example 11)
In Example 11, in the stacking process STEP 6 in FIG. 1 , a boric acid aqueous solution having a concentration of 0.3 g/L was applied to the first surface 21a of the first SiC calcined body 21 and the second surface 22a of the second SiC calcined body 22, and then the first and second SiC sintered bodies 21, 22 were stacked together, and the SiC sintered member 30 was produced in the same manner as in Example 8, except that.

As with Example 8, no poor bonding or damage was observed at the joints of this SiC sintered member 30, and no damage or distortion was observed in the hollow structure originating from the recess 23.

The results of Examples 8 to 11 are summarized in Table 3.

(Examples 12 to 15)
In Examples 12 to 15, the first SiC calcined body obtaining process STEP 1, the second SiC calcined body obtaining process STEP 2, the first plane forming process STEP 3, the second plane forming process STEP 4, and the recess forming process STEP 5 were performed in the same manner as in Example 8 described above.

Next, in the bonding material forming step STEP5-1, in Examples 12 and 15, IPA was used as a solvent, and a Si particle-containing slurry was prepared so that the volume-based median diameter (D50) of the Si particles was 3 μm. Next, using a plasma spraying device, the prepared Si particle-containing slurry was supplied to the nozzle of the plasma device and plasma sprayed on the second surface 2a to form a bonding material 6 made of a Si sprayed film. At this time, the spraying distance was 75 mm. The conditions of the plasma spraying were controlled to a supply power of 65 kW, an Ar gas supply rate of 100 L/min, an N ₂ gas supply rate of 70 L/min, and an H ₂ gas supply rate of 70 mL/min. The thickness of the bonding material 6 was 8 μm.

In Example 13, a Si paste was prepared using metal Si particles with a volume-based median diameter (D50) of 1 μm in an organic vehicle containing PVB as a binder, DBP as a plasticizer, and butyl carbitol acetate as a solvent. The prepared Si paste was applied to the second surface 2a and heat-treated at 200°C in an air atmosphere for 1 hour to form a bonding material 6 made of Si particles and the like. The thickness of the bonding material 6 was 15 μmm.

On the other hand, in Example 14, a SiC paste was prepared using SiC particles with a volume-based median diameter (D50) of 1 μm and the organic vehicle used in Example 13. The prepared SiC paste was applied to the second surface 2a and heat-treated at 200°C in an air atmosphere for 1 hour to form a solid bonding material 6 made of SiC particles. The thickness of the bonding material 6 was 15 μmm.

Next, in the stacking step STEP 6, referring to FIG. 7B, the first SiC calcined body 1 and the second SiC calcined body 2 were stacked with the first plane 1a and the second plane 2a in contact with each other via the bonding material 6.

Next, in the firing step STEP 7, the first and second SiC calcined bodies 1, 2 and the bonding material 6 thus stacked were sandwiched between carbon flat plates as pressing plates in an argon atmosphere in a firing furnace, and fired for 3 hours at a furnace temperature of 2070° C. while applying a load of 0.005 kgf/cm ² (=490 Pa) in Examples 1 to 6 and a load of 10 kgf/cm ² (=0.98 MPa) in Example 7 in the stacking direction. As a result, a SiC sintered member 10 was obtained as shown in FIG. 7C. The bulk density of the SiC sintered member 10 was as shown in Table 4.

Then, this SiC sintered component 10 was cut to include the joint, the cut surface was polished, and the joint was visually inspected by an experimenter using a magnifying glass or the like. As a result, no poor bonding or damage was found at the joint, and no damage or distortion was found in the hollow structure originating from the recess 3.

The results of Examples 12 to 15 are summarized in Table 4.

1, 11, 21...first SiC calcined body; 1a, 11a, 21a...first plane; 2, 12, 22...second SiC calcined body; 2a, 12a, 22a...second plane; 3, 14, 23...recess; 13...third SiC calcined body; 15...peeling material; 6, 16...jointing material; 10, 20, 30...ceramic sintered body.

Claims (9)

calcining the first SiC compact at a temperature of 1200° C. or higher and 1900° C. or lower to obtain a first SiC calcined body;
calcining the second SiC compact at a temperature of 1200° C. or higher and 1900° C. or lower to obtain a second SiC calcined body;
forming a first plane on the first SiC calcined body;
forming a second plane on the second SiC calcined body;
forming a recess in at least one of the first plane or the second plane;
stacking the first SiC calcined body and the second SiC calcined body in a state in which the first plane and the second plane are in contact with each other;
and firing the stacked first SiC calcined body and the second SiC calcined body at 2000°C or higher and 2200°C or lower while applying a pressure of 10 kgf/cm2 or ^higher in the stacking direction. The method for manufacturing a SiC sintered component according to claim 1, characterized in that in the lamination process, a sintering aid containing boron is interposed between the first plane and the second plane. calcining the first SiC compact at a temperature of 1200° C. or higher and 1900° C. or lower to obtain a first SiC calcined body;
calcining the second SiC compact at a temperature of 1200° C. or higher and 1900° C. or lower to obtain a second SiC calcined body;
forming a first plane on the first SiC calcined body;
forming a second plane on the second SiC calcined body;
forming a recess in at least one of the first plane or the second plane;
A step of forming a bonding material made of a Si sprayed film obtained by thermal spraying, or a silicon powder or a SiC powder obtained by heat treating a paste, on at least one of the first plane or the second plane;
laminating the first SiC calcined body and the second SiC calcined body in a state in which the first plane and the second plane are in contact with each other via the bonding material;
and firing the stacked first and second SiC calcined bodies at 1900°C or higher and 2200°C or lower while applying a pressure of 0.005 kgf/ ^cm2 or higher in the stacking direction. The method for manufacturing a SiC sintered member according to any one of claims 1 to 3 , further comprising a step of storing the first SiC calcined body and the second SiC calcined body prior to the step of forming the recess. The method further includes a step of calcining the third SiC compact at a temperature of 1200° C. or more and 1900° C. or less to obtain a third SiC calcined body;
In the stacking step, the third SiC calcined body is stacked on the outer side of the first SiC calcined body or the second SiC calcined body in a stacking direction via a release material;
5. The method for manufacturing a SiC sintered member according to claim 1, wherein in the firing step, the pressure is applied to the first SiC calcined body, the second SiC calcined body and the third SiC calcined body which are stacked. calcining the first SiC compact at a temperature of 1200° C. or higher and 1900° C. or lower to obtain a first SiC calcined body;
calcining the second SiC compact at a temperature of 1200° C. or higher and 1900° C. or lower to obtain a second SiC calcined body;
calcining the third SiC compact at a temperature of 1200° C. or higher and 1900° C. or lower to obtain a third SiC calcined body;
forming a first plane on the first SiC calcined body;
forming a second plane on the second SiC calcined body;
forming a recess in at least one of the first plane or the second plane;
stacking the first SiC calcined body and the second SiC calcined body in a state in which the first plane and the second plane are in contact with each other via a bonding material, and stacking the third SiC calcined body on the outer side of the first SiC calcined body or the second SiC calcined body in a stacking direction via a release material;
The first, second and third SiC calcined bodies were subjected to a pressure of 0.005 kgf/cm in the stacking direction. ² and sintering the mixture at 1900°C or higher and 2200°C or lower while applying the above pressure. 7. The method for producing a SiC sintered member according to claim 6, wherein the bonding material is any one of silicon powder, SiC powder, and a silicon sprayed film. The method for producing a SiC sintered member according to claim 6 or 7, further comprising a step of storing the first SiC calcined body and the second SiC calcined body prior to the step of forming the recess. 9. A method for manufacturing a SiC sintered member according to claim 1, wherein at least one of the first plane, the second plane, and the recess is formed by dry grinding or polishing.

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