JP2010173921A - Silicon carbide joined body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joined body having high joining strength and airtightness and being excellent in size accuracy in a hollow part. <P>SOLUTION: The silicon carbide joined body where a first silicon carbide sintered body 11 and a second silicon carbide sintered body 12 are joined via joining layers 141, 142 consisting of metal silicon and silicon carbide has the airtight hollow part 15 between a plurality of the joining layers 141, 142 in its cross section. The silicon carbide joined body is characterized in that surfaces facing to the airtight hollow part 15 of the first and second silicon carbide sintered bodies have a surface roughness Rz of 2.5 &mu;m or more. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a silicon carbide bonded body. In particular, the present invention relates to a joined body suitable for a member that requires airtightness and high adhesion at a joint. For example, the present invention can be applied to a liquid recovery unit in an immersion exposure apparatus and a shower plate that is a gas supply unit such as a CVD apparatus.

Silicon carbide is excellent in heat resistance and corrosion resistance, and is often used as a member for semiconductor manufacturing equipment, but silicon carbide has a high sintering temperature and the atmosphere is also under an inert gas. There is a limit in size to form. Therefore, various joining techniques have been proposed.

For example, Patent Document 1 discloses that an air-pressure-sintered SiC sintered body having a bulk density of 2.8 g / cm ³ or more is joined to Si, and open pores that open to the joint surface of the normal-pressure sintered SiC sintered body. And a technique for joining via a filling part made of Si integral with the joint part, in which granular Si having a particle size of 0.05 mm is mixed with ethanol to form a paste, An example in which 02 mm plate-like Si is interposed between SiC sintered bodies and joined is shown.

Patent Document 2 discloses that a bonded surface of two or more silicon carbide-based members is coated with a slurry containing a resin and a silicon powder as a carbon source and then bonded, and then the bonded silicon carbide-based member. Is baked at a temperature of 900 to 1300 ° C. in a vacuum or an inert atmosphere to carbonize the resin, and then the carbonized silicon carbide-based member is baked at a temperature of 1300 ° C. or higher in a vacuum or an inert atmosphere. A manufacturing method of a silicon carbide-based member joined body is shown in which silicon carbide is formed on the joint surface by processing and reacting and sintering carbon from silicon and resin.

JP 2002-145679 A JP-A-60-161384

However, as in the inventions described in Patent Document 1 and Patent Document 2, in a method in which metal silicon powder or the like is filled and bonded, or metal silicon of a plate material is used as a bonding material, bleeding from the bonded portion occurs. There were many problems. For example, in the case of a joined body having a hollow portion, the amount of metallic silicon that melts and exudes cannot be controlled. It was happening.

In particular, in an immersion exposure apparatus, a CVD apparatus, or the like, there are members having a shape that is difficult to be integrally formed such that a fine groove or hole for supplying or recovering liquid or gas is formed and a hollow portion is formed. In order to form such a fine structure, the shape of the hollow portion formed by bonding must be precisely adjusted, so the shape accuracy of the hollow portion has been a big problem.

The present invention has been made in view of these problems, and provides a silicon carbide bonded body that has a high bonding strength and airtightness, and that can provide a bonded body having a hollow portion with excellent shape accuracy even when it has a hollow portion. .

In order to solve these problems, the present invention provides a silicon carbide in which a first silicon carbide sintered body and a second silicon carbide sintered body are bonded via a plurality of bonding layers made of metal silicon and silicon carbide. A surface of a bonded body having a hermetic hollow portion between a plurality of the bonding layers and facing the hermetic hollow portion of the first and second silicon carbide sintered bodies in the cross section thereof A silicon carbide joined body having a roughness Rz (JIS B0601: 2001) of 2.5 μm or more is provided.

By forming a bonding layer made of metal silicon and silicon carbide, and by adjusting the surface roughness Rz on the surface of the silicon carbide sintered body facing the hermetic hollow portion formed between the plurality of bonding layers in the cross section, the hollow portion The shape accuracy can be increased.

The surface roughness Ra of the joint surfaces of the first and second silicon carbide sintered bodies is preferably 0.6 μm or less. As for the bonding surface, it is preferable to reduce the surface roughness Ra (JISB0601: 2001) to improve the airtightness.

The bonding layer preferably has a silicon carbide content of 5 to 20% by mass. By including silicon carbide in the metal silicon, it is possible to suppress the seepage, and to adjust the surface roughness Rz of the silicon carbide sintered body in the hollow portion, the shape accuracy of the hollow portion can be improved.

The average particle size of silicon carbide contained in the bonding layer is preferably 1 to 20 μm. By adjusting the surface roughness Rz of the silicon carbide sintered body in the hollow part and further adjusting the silicon carbide content of the bonding layer and the average particle diameter of silicon carbide, the seepage into the hollow part can be suppressed.

The silicon carbide joined body of the present invention achieves a 4-point bending strength of 250 MPa or more in accordance with JIS R1624. In addition to airtightness, it has excellent bonding strength, so it can be used as various members. It is particularly suitable for a member having many hollow portions formed between the joining layers.

It is possible to provide a silicon carbide bonded body that has a high bonding strength and airtightness, and that can provide a bonded body having a hollow portion with excellent shape accuracy even when it has a hollow portion.

Schematic sectional view showing a method for manufacturing a silicon carbide joined body of the present invention. The hollow part expansion schematic sectional drawing of the silicon carbide joined body of this invention. The schematic sectional drawing which showed the silicon carbide joined body shape. The schematic sectional drawing which showed the silicon carbide joined body shape.

Hereinafter, the silicon carbide bonded body of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a method for manufacturing a silicon carbide bonded body according to the present invention. FIG. 1 (c) shows an example of the silicon carbide bonded body according to the present invention.

As shown in FIG. 1 (c), the silicon carbide bonded body of the present invention includes a first silicon carbide sintered body 11 and a second silicon carbide sintered body 12, a plurality of bonding layers 141 and a bonding layer 142. Thus, an airtight hollow portion 15 is formed between the bonding layer 141 and the bonding layer 142.

In the present invention, the airtightness of the hollow portion is achieved by the bonding layer. As described in Patent Documents 1 and 2, when joining silicon carbide sintered bodies with metal silicon powder or metal silicon plate, the seepage when the metal silicon powder or the like melts is remarkable, and there is a gap in the joining layer. Is likely to occur. On the other hand, since silicon carbide is contained in the present invention, even if it is melted, the seepage can be suppressed to a small extent, so that a gap is not easily formed in the bonding layer. Therefore, since it can join without a gap, airtightness can be improved. Here, as an airtightness standard, an equivalent standard leak amount in a helium leak test by a bombing method in accordance with JISZ2331 is set to be smaller than 1 × 10 ⁻⁶ Pa · m ³ / s.

The hermetic hollow portion is formed between the plurality of bonding layers in the cross section of the silicon carbide bonded body. Therefore, the airtight hollow portion includes not only the groove as shown in the figure but also an internal space that does not communicate with the outside as in the groove. Further, there are a plurality of bonding layers of the silicon carbide bonded body in the cross section including the airtight hollow portion, and the bonding layer in the bonded body may be one. For example, this is a case where the bonding layer is annular.

Further, it is desirable that the surface roughness Rz of the surfaces of the first silicon carbide sintered body 11 and the second silicon carbide sintered body 12 facing the airtight hollow portion 15 is 2.5 μm or more. By setting the surface roughness Rz to the above range for the portion that is not bonded by the bonding layer and using metal silicon containing silicon carbide as the bonding layer, the seepage into the hollow portion can be suppressed. This is because the surface roughness Rz of the portion where the bonding is not performed is sufficiently rougher than the surface roughness Ra of the bonding surface, so that the silicon carbide particles in the bonding layer are uneven in the portion where the adjacent bonding is not performed. This is because the movement is suppressed. From such a viewpoint, the surface roughness Rz of the portion where bonding is not performed is preferably 2.5 μm or more, and more preferably 20 to 40 μm. The upper limit of the surface roughness Rz of the bottom and side surfaces of the groove is not particularly limited. However, if Rz is larger than 40 μm, there is a risk of cracking and the like, which is not preferable.

FIG. 2 is an enlarged schematic cross-sectional view of the hollow portion of the silicon carbide joined body of the present invention. The plurality of bonding layers 241 and 242 and the surfaces 21 b and 22 b of the silicon carbide sintered body face the hollow portion 25. By controlling the surface roughness Rz of the surfaces 21b and 22b as described above, the seepage of metal silicon into the hollow portion can be suppressed.

At this time, the surface roughness Ra of the bonding surfaces of the first and second silicon carbide sintered bodies that are in contact with the bonding layer is preferably 0.6 μm or less. This is because the bonding layer made of metal silicon containing silicon carbide is firmly adhered to the bonding surface having a small surface roughness Ra, and the bonding layer contains silicon carbide. This is because it is difficult to flow after the contact. Therefore, it is desirable that the surface roughness Ra of the joint surface is small and the surface roughness Rz of the surface facing the hollow portion is large. From such a viewpoint, the surface roughness Ra of the joint surface is preferably 0.6 μm or less, and more preferably 0.3 μm or less.

FIG. 3 shows a modified example of the joined body. The first silicon carbide sintered body 31 is provided with a groove 31b that forms a hollow portion. Such a groove forms a hollow portion between the plurality of bonding layers, and the surface thereof faces the hollow portion. Therefore, even in such a configuration, it is desirable that the surface facing the hollow portion, that is, the bottom surface and the side surface of the groove have a surface roughness of Rz 2.5 μm or more. The shape of the groove in FIG. 3 is a square shape in which the bottom surface and the side surface form a right angle. can do.

In FIG. 4, grooves 41b and 42b are formed in both the first and second silicon carbide sintered bodies 41 and. Also in this case, as in the case of FIG. 3, it is desirable that the bottom surface and the side surface of the groove have a surface roughness Rz of 2.5 μm or more.

Next, the manufacturing method of the silicon carbide joined body of this invention is demonstrated. The silicon carbide sintered bodies 11 and 12 shown in FIG. 1 can be produced by a molding method such as press molding, CIP molding, and casting molding, and a sintering method such as atmospheric pressure sintering, pressure sintering, and reaction sintering. . The surface roughness Ra of the joint surfaces 11a and 12a can be adjusted by grinding with a surface grinder and further by lapping or the like.

Usually, an oxide film is formed on the surface of the silicon carbide sintered body, and as it is, the wettability with metal silicon is insufficient, so that a reduction treatment such as applying and heating carbon is performed. . However, when carbon is applied, reaction sintering may also occur due to the reaction between metallic silicon and carbon, which may reduce the bonding strength. Therefore, in this invention, it joins, without performing such a reduction process.

Further, in joining silicon carbide sintered bodies via a joining material, the reduction treatment as described above is generally performed after a treatment for roughening the joining surface by blasting or the like. This is to increase the bonding strength by generating an anchor effect between the bonding surface and the bonding layer. However, in the present invention, conversely, the surface roughness Ra of the joint surface is reduced. The reason for this is that an oxide film is formed on the surface of the silicon carbide sintered body, which causes a decrease in wettability with metallic silicon. In the bonding method of the present invention, the surface roughness Ra is smaller. This is because the bonding strength can be increased. This is considered to be because when the surface roughness Ra is large, the influence of the oxide film on the surface is large and it becomes difficult to wet.

FIG. 1B shows a state in which raw material powder layers 131 and 132 serving as a bonding layer are formed on the bonding surface 11 a of the first silicon carbide sintered body 11. The bonding layer can be formed by wet-mixing silicon carbide and metal silicon, forming a slurry, and filling the bonding surface of the base material. Alternatively, dry-mixed powder may be filled in the bonding surface 11a of the first silicon carbide sintered body 11. In addition, a raw material sheet obtained by previously forming a sheet of silicon carbide and metal silicon by adding a binder or the like may be installed on the bonding surface. Depending on the shape of the joined body to be produced, positional deviation may occur unless the raw material powder or the raw material sheet is firmly adhered to the joining surface of the first silicon carbide sintered body 11, and therefore an adhesive is used as necessary. Or may be heated. In addition, when organic substances, such as a binder, are added, it is desirable to degrease so that reaction of carbon and metal silicon may not occur in the bonding layer. Degreasing is possible, for example, by heating in the atmosphere of 500 to 700 ° C.

In FIG. 1B, a plurality of raw material powder layers 131 and 132 are formed. In order to form in this way, a mask is applied so that a space is formed between both layers, a sheet molded in a predetermined shape is used, a raw material powder is filled, or a raw material sheet is installed Alternatively, it may be removed by blasting or the like to form a space. In addition, in the example of FIGS. 1-4, although the hollow part is formed between two joining layers, this invention is not limited to this, A joining layer is two or more, Comprising: In which is 1 or more.

Adjustment of the surface roughness Rz of the surface facing the airtight hollow portion of the silicon carbide sintered body is not particularly limited as long as it can be roughened by sandblasting or the like, and can be performed by various methods.

The purity of the metal silicon used for the bonding layer is preferably 97% or more, more preferably 99% or more, and still more preferably 99.9% or more. This is because when there are many impurities, the melting temperature is lowered, and problems such as seepage occur.

The content of silicon carbide in the bonding layer is preferably 5 to 20% by mass. When the content rate of silicon carbide is less than 5% by mass, when the metal silicon is melted, the metal silicon cannot be held on the joint surface and may leak into the hollow portion. In addition, when the silicon carbide content is greater than 20% by mass, silicon carbide is present in a relatively large amount, and metal silicon is difficult to melt and integrate with each other. As a result, there is a risk that adhesion to the joint surface cannot be obtained. Moreover, since voids are easily generated in the bonding layer, the bonding strength may be significantly reduced.

The average particle size of silicon carbide in the bonding layer is desirably 1 to 20 μm. When the average particle diameter of silicon carbide is less than 1 μm, the surface area of silicon carbide is large, so that there is a risk that wetting of metal silicon will be insufficient. If the wetting is not sufficient, voids are likely to be generated in the bonding layer, and the bonding strength may be significantly reduced. When the average particle size of silicon carbide is larger than 20 μm, the specific surface area in contact with the metal silicon is reduced, so that the effect of suppressing the reduction in viscosity at the time of melting the metal silicon is reduced. As a result, the metal silicon can move in the bonding layer, so that bleeding into the hollow portion occurs and there is a possibility that voids may be formed between the silicon carbide particles after the metal silicon has oozed out.

Next, the bonding surface 12a of the second silicon carbide sintered body 12 is brought into contact with the raw material powder layers 131 and 132 and bonded by heat treatment. The heat treatment temperature is preferably 1410 to 1500 ° C. at which metal silicon melts, and the heat treatment time is preferably 30 to 60 minutes. The heat treatment atmosphere is preferably in a vacuum, and preferably 0.01 kPa to 1 kPa. Moreover, it is desirable to apply a load of 4 to ²⁰ g / cm ² at the time of joining. If a load greater than this is applied, the carbonization of the metallic silicon at the joint proceeds and the joining strength tends to decrease, such being undesirable.

Hereinafter, the present invention will be described with reference to test examples of bonding strength and airtightness.

The silicon carbide sintered body was formed by a CIP method using a commercially available silicon carbide powder (UF-10 manufactured by Stark) and fired at 2100 ° C. in argon. A silicon carbide sintered body (silicon carbide sintered body 31: φ50 mm, thickness 25 mm, counterbore 31b: φ5, depth 2 mm, silicon carbide sintered body 32: φ50 mm, thickness 25 mm) as shown in FIG. 3 is produced. did. These shape processes were performed by a known method such as surface grinding, and the surface roughness Ra of the joint surface was adjusted. About the part used as the surface which faces a hollow part, the sandblasting process was performed. The surface roughness was measured based on JISB0601: 2001.

Next, formation of the raw material powder layer of the bonding layer will be described. After silicon carbide powder (average particle size 10 μm) and metal silicon are wet-mixed at a mass ratio of 1: 9 to form a slurry, filled in the joint surface of the first silicon carbide sintered body, and dried at 100 ° C., The raw material powder layer was formed by processing. When filling the raw material powder slurry, a mask was applied to the surface portion facing the hollow portion. The thickness of the raw material powder layer was 500 μm. In addition, the average particle diameter of silicon carbide powder is a median diameter (D50) by laser diffraction type particle size distribution measurement.

Next, the second silicon carbide sintered body was brought into contact with the raw material powder layer and subjected to heat treatment for bonding. The heat treatment temperature in the bonding step was 1450 ° C., the heat treatment time was 30 minutes, and the heat treatment atmosphere was in vacuum (0.1 kPa). Further, a load of 15 g / cm ² was applied at the time of joining.

By the above method, the surface roughness Rz of the surface facing the airtight hollow portion of the silicon carbide sintered body, the surface roughness Ra of the bonding surface of the silicon carbide sintered body, the silicon carbide content in the bonding layer, and the silicon carbide The joined body was produced by changing the average particle size. For comparison, a joined body was produced using the metal silicon powder described above as a joining material.

About the joining layer, the cut surface was observed with the optical microscope, and the hollow part was investigated. For the bonding strength, a test piece (3 mm × 4 mm × 40 mm) was cut out from the bonded body, and a four-point bending test (JISR1624 compliant) with a lower span of 30 mm and an upper span of 10 mm was performed to determine the bonding strength. The airtightness test was performed by a bombing method in accordance with JISZ2331. Regarding the observation of the hollow part, the joined body was cut so as to pass through the hollow part having a diameter of 5 mm and a depth of 2 mm, and the presence or absence of metal silicon was observed visually. The results are shown in Table 1. In the evaluation of the hollow portion, the case where the bonding material did not ooze out was evaluated as ◯, and the case where the bonding material was closed was evaluated as x.

In Test Nos. 3 to 9, 14, 16 to 20, 23 to 24, and 27, the equivalent reference leak amount was 1 × 10 ⁻⁶ Pa · m ³ / s or less, and the hollow portion was not blocked. . The bonding strength was 253 to 284 MPa, which was a high value of 250 MPa or more.

On the other hand, in No. 1 and No. 2 where the surface roughness Rz of the hollow portion is large, the equivalent reference leak amount is 1 × 10 ⁻⁶ Pa · m ³ / s or more, and the He leak is remarkable. Moreover, the bonding strength showed a low value of less than 200 MPa. This is because the surface of the hollow portion is smooth, so that the silicon carbide particles in the bonding layer can be easily moved.

On the other hand, in Nos. 10 to 11 having a large surface roughness Ra of the joint surface, the equivalent reference leak amount was 1 × 10 ⁻⁶ Pa · m ³ / s or more, and the He leak was remarkable. Moreover, the bonding strength showed a low value of less than 200 MPa. The cause of the leakage and the decrease in bonding strength is that the surface roughness Ra of the bonding surface is 0.6 μm or more, so the influence of the oxide film on the silicon carbide bonding surface becomes significant, the wettability of the bonding layer decreases, and the voids This is thought to have occurred.

In No. 12-13 with little silicon carbide content rate, obstruction | occlusion of the hollow part was recognized in the hollow part observation of the cut surface of a conjugate | zygote. This is probably because the silicon carbide in the bonding layer has a low volume ratio, so when the metal silicon is melted, the metal silicon cannot be held on the bonding surface and oozes out into the hollow portion. Moreover, in No. 25-26 with much silicon carbide content rate, an equivalent reference amount is 1 * 10 < ^-6 > Pa * m < ³ > / s or more, He leak was recognized and obstruction | occlusion was recognized by the hollow part. Moreover, the bonding strength showed a low value of less than 200 MPa. This is because there is a relatively large amount of silicon carbide and it is difficult for the metal silicon to melt and integrate, so that the metal silicon reacts with the carbon in the furnace and the fluidity is lowered, so that adhesion with the joint surface cannot be obtained. At the same time, it is considered that voids are easily generated in the bonding layer.

Further, in No. 15 in which the particle size of silicon carbide is small, the equivalent reference leak amount is 1 × 10 ⁻⁶ Pa · m ³ / s or more, and the He leak is remarkable. Moreover, the bonding strength showed a low value of less than 200 MPa. This is presumably because the silicon carbide has a large surface area, so that the metal silicon is insufficiently wetted and voids are generated in the bonding layer. In Nos. 21 to 22 having a large silicon carbide particle size, the equivalent reference amount was 1 × 10 ⁻⁶ Pa · m ³ / s or more, a He leak was observed, and a clogging in the hollow portion was also observed. Also, the bonding strength was low. This is because the specific surface area in contact with the metal silicon is reduced, the effect of suppressing the decrease in viscosity at the time of melting the metal silicon is reduced, and the metal silicon can move within the bonding layer, so that the seepage into the hollow portion is prevented. It is considered that voids remain between the silicon carbide particles that are generated and the metal silicon has moved.

Furthermore, in No. 28, in the observation of the hollow portion of the cut surface of the joined body, the hollow portion was clogged. This is probably because silicon carbide was not included in the bonding layer, so that bleeding, positional deviation, and voids occurred.

10, 30, 40; joined bodies 11, 21, 31, 41; first silicon carbide sintered bodies 12, 22, 32, 42; first silicon carbide sintered bodies 11a, 12a; joined surfaces 21b, 31b, 41b; surfaces 22b, 42b facing the hollow part; surfaces 131, 132 facing the hollow part; raw powder layers 141, 142, 241, 242, 34, 44; bonding layers 15, 25; hollow part

Claims (4)

A silicon carbide joined body in which a first silicon carbide sintered body and a second silicon carbide sintered body are joined via a joining layer made of metal silicon and silicon carbide,
In its cross section, it has an airtight hollow portion between the plurality of bonding layers,
A silicon carbide joined body, wherein the first and second silicon carbide sintered bodies have a surface roughness Rz of 2.5 μm or more facing the airtight hollow portion. 2. The silicon carbide bonded body according to claim 1, wherein a surface roughness Ra of a bonding surface of the first and second silicon carbide sintered bodies is 0.6 μm or less. The silicon carbide bonded body according to claim 1, wherein the bonding layer has a silicon carbide content of 5 to 20 mass% and an average particle size of silicon carbide of 1 to 20 μm. The silicon carbide joined body according to claim 1 or 2, wherein a four-point bending strength in accordance with JIS R1624 is 250 MPa or more.

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