JP5466439B2 - Ceramic joined body, ceramic heater, electrostatic chuck and susceptor - Google Patents

Description

The present invention relates to a ceramic joined body. The ceramic joined body of the present invention is particularly suitable for a ceramic heater, an electrostatic chuck, a susceptor or the like.

In the semiconductor manufacturing process, film formation and etching are performed to form an integrated circuit on a silicon wafer. In these steps, in order to uniformly process the silicon wafer, it is important to uniformly heat and maintain the entire surface of the wafer at a predetermined temperature. For heating the wafer, heating by a ceramic heater is widely used, and a heating resistor, an electrostatic chuck electrode, and an RF electrode are widely used. This ceramic heater includes a heating resistor terminal and an electrostatic chuck electrode terminal, and a sheath thermocouple is inserted into a part of the heater for temperature measurement. These terminals are connected to a copper wire or a nickel wire and drawn out of the processing chamber of the silicon wafer. The same applies to the sheath thermocouple.

The environment for processing the silicon wafer is a high temperature and corrosive gas atmosphere. Under such an environment, corrosion of the terminals and conductors occurs unless the terminals and conductors are protected. Therefore, a protective tube is often provided in the ceramic heater, and a terminal and a thermocouple are often disposed therein (see Patent Document 1).

For example, Patent Document 1 discloses a bonded body in which a cylindrical body made of nitride ceramic is bonded to the bottom surface of a nitride ceramic substrate in which a conductor is provided, and the inside of the nitride ceramic substrate. Has been proposed that contains 5% by mass or more of a sintering aid. Since this joined body is different from the content of the sintering aid in the cylindrical body and the content of the sintering aid in the nitride ceramic substrate, the nitride ceramic substrate, the tubular body, There is a relationship that forms a gentle slope curve between the distance from the surface of the nitride ceramic substrate and the content of the sintering aid at the interface and in the vicinity of the interface.

As a result, the sintering aid in the aluminum nitride substrate diffuses into the cylindrical body with a small amount of the sintering aid, and the aluminum nitride particles present at the interface between the aluminum nitride substrate and the cylindrical body are: According to the diffusion of the sintering aid, it joins and grows. The aluminum nitride particles that have grown at the interface between the aluminum nitride substrate and the cylindrical body firmly bond the aluminum nitride substrate and the cylindrical body. In such bonding, there is no need to bond the nitride ceramic substrate and the columnar body via the ceramic bonding layer, or to apply a solution containing a sintering aid to the surfaces to be bonded. Corrosion resistance at the interface and its vicinity can be improved.

JP 2003-292386 A

However, in the bonded body as described above, diffusion of the sintering aid and grain growth occur at the bonded interface, and thus the characteristics of the sintered body at the bonded interface and in the vicinity thereof change. In particular, when the thermal conductivity and volume resistivity change, it becomes difficult to uniformly treat the silicon wafer when the joined body is used as a ceramic heater or the like.

Further, when diffusion or grain growth occurs, the sintered body is likely to be deformed. Especially in ceramic heaters and electrostatic chucks, heating resistors and electrodes are embedded in the sintered body, and the distance between these and the silicon wafer is extremely important for the uniform processing of the silicon wafer. Deformation of the sintered body is not preferable.

The present invention has been made in view of these problems, and provides a ceramic joined body with little deformation and no change in the properties of the sintered body at and near the joining interface.

In order to solve these problems, the present invention provides the following inventions (1) to (8) .
(1) A ceramic joined body in which the first ceramic sintered body and the second ceramic sintered body are joined without using a joining material, and the first and second ceramic sintered bodies are common to each other. to, aluminum nitride, as a main component one of aluminum oxide and silicon nitride, the first and second one or both of the ceramics sintered body includes a subcomponent, the second ceramic sintered body The ceramic has a thermal conductivity smaller than that of the first ceramic sintered body, and the subcomponent of one ceramic sintered body does not diffuse into the other ceramic sintered body. Joined body.
(2) The ceramic joined body according to (1), wherein the first ceramic sintered body and the second ceramic sintered body do not show grain growth during joining.
(3) The ceramic joined body according to (1) or (2), wherein the first ceramic sintered body has a metal conductor embedded therein.
(4) The first ceramic sintered body has a plate shape having a main surface on which the substrate is placed, and the second ceramic sintered body has an end portion of the first ceramic sintered body. The ceramic joined body according to any one of (1) to (3), which has a cylindrical shape joined to a surface on the back side of the main surface.
(5) The ceramic joined body according to (3) , wherein the metal conductor is a heating resistor, an electrostatic electrode, or an RF electrode.
(6) A ceramic heater using the ceramic joined body according to any one of (3) to (5) .
(7) An electrostatic chuck using the ceramic joined body according to any one of (3) to (5) .
(8) A susceptor using the ceramic joined body according to any one of (3) to (5) .

There is no change in the properties of the sintered body at and near the bonding interface, and a ceramic bonded body with less deformation can be provided.

It is a schematic sectional drawing of a ceramic joined body. It is an example of a measurement of a subcomponent of a ceramic joined body. It is an example of a measurement of the average particle diameter of a ceramic joined body. It is a schematic sectional drawing of a ceramic heater.

Hereinafter, it will be described in more detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a ceramic joined body 10 of the present invention. The first ceramic sintered body 11 and the second ceramic sintered body 12 are joined without using a joining material.

What showed the example which measured the amount of the subcomponent contained in both sintered compacts from the 1st ceramic sintered compact 11 toward the 2nd ceramic sintered compact 12 about the junction part A of this ceramic joined body 10 is shown. FIG.

In FIG. 2, the first and second ceramic sintered bodies are mainly composed of components common to each other,
An example of measurement was shown in which both the first and second ceramic sintered bodies contain subcomponents, and the first ceramic sintered body contains more subcomponents than the second ceramic sintered body. As can be seen from FIG. 2, in the ceramic joined body, it can be seen that the amount of subcomponents is different at the joining interface which is the boundary between the first ceramic sintered body and the second ceramic sintered body. The amount of each subcomponent is equal to that before bonding, and indicates that the subcomponent has not diffused into the sintered ceramics after bonding.

The reason why such a bonded body is obtained is that the bonding is not performed using subcomponents such as a sintering aid contained in the ceramic sintered body, but diffusion of the main ceramic component is used. "One or both of the first and second ceramic sintered bodies contain subcomponents, and the subcomponent of one ceramic sintered body does not diffuse into the other ceramic sintered body. "When both ceramic sintered bodies contain subcomponents as described above, they do not diffuse with each other, one ceramic sintered body contains subcomponents and the other contains subcomponents. If not, it means that the auxiliary component has not diffused from the one ceramic sintered body to the other ceramic sintered body.

With such a configuration, the sintered body characteristics do not change due to diffusion of subcomponents at or near the bonding interface, so that the thermal conductivity and volume resistivity do not change. Therefore, for example, when a ceramic joined body is used as a ceramic heater, it becomes easy to uniformly treat a silicon wafer.

FIG. 3 shows the average grain at each measurement position of the crystal particles of both sintered bodies from the first ceramic sintered body 11 toward the second ceramic sintered body 12 in the joined portion A of the ceramic joined body 10. The diameter was measured. In the example of FIG. 3, the ceramic bonded body has different particle sizes with the bonding interface as a boundary. And the particle size of both sintered compacts does not change before and after joining. That is, no grain growth is observed during bonding.

In this way, it is possible to suppress deformation of the ceramic joined body by suppressing grain growth. In particular, when it is applied to a ceramic heater or electrostatic chuck in which a heating resistor or an electrode is embedded in the sintered body, it exerts a great effect in uniformly processing a silicon wafer.

FIG. 4 shows a ceramic joined body according to the present invention applied to a ceramic heater. The ceramic heater 20 is formed by joining a plate-shaped first ceramic sintered body 21 having a main surface 21a on which a workpiece such as a silicon wafer is placed and a cylindrical second ceramic sintered body 22. . The back surface 21b of the first ceramic sintered body 21 and the end portion 22a of the second ceramic sintered body 22 are joined together as joint surfaces.

In the first ceramic sintered body 21, metal conductors such as a heating resistor 23 and a temperature measuring element 24 such as a thermocouple are embedded. The above example is a ceramic heater, but in the case of an electrostatic chuck or susceptor, an electrostatic electrode or an RF electrode is embedded. When a ceramic heater and an electrostatic chuck or susceptor are used in combination, a plurality of these may be embedded. In a member such as a ceramic heater in which a metal conductor such as a heating resistor is embedded, it is necessary to uniformly heat or adsorb the member. Therefore, the main surface 21a on which the object to be processed is placed and the metal conductor The distance must be controlled with extremely high accuracy. Therefore, a large deformation occurring when the first ceramic sintered body and the second ceramic sintered body are joined can be a fatal defect in a ceramic heater or the like.

In this invention, since the deformation | transformation of the sintered compact at the time of joining is suppressed, the above problems do not arise. Therefore, if the metal conductor is embedded with high accuracy in the first ceramic sintered body used for bonding, the accuracy of the metal conductor after bonding is maintained.

The ceramic heater of FIG. 4 has a structure in which a back surface 21b of the main surface 21a of the plate-shaped first ceramic sintered body 21 and an end portion 22a of the cylindrical second ceramic sintered body are joined. Have. The ceramic heater is installed in a vacuum chamber that is a processing chamber for an object to be processed. The vacuum chamber and the ceramic heater are fixed on the other end side of the second ceramic sintered body. The vacuum chamber is fixed via, for example, a flange 25. The flange can be configured to be vacuum-tight by an air-tight mechanism such as an O-ring. The second ceramic sintered body 22 and the flange 25 may be fixed by bonding with a bonding material such as ceramics, metal, glass, or a fixing bolt.

The heating resistor 23 and the temperature measuring element 24 embedded in the first ceramic sintered body 21 are connected to a power supply line 26 and a temperature measuring element conducting wire 26, and a cylindrical second ceramic sintered body cylinder is formed. It passes through and is connected to a temperature control device (not shown) via a feedthrough 28 provided in the flange 25.

By joining the first ceramic sintered body 21 and the second ceramic sintered body 22, the inside of the cylinder of the second ceramic sintered body 22 and the inside of the vacuum chamber are hermetically sealed. Therefore, since the inside of the cylinder is normally exposed to the atmosphere, the heating resistor 23 and the temperature measuring element 24 are connected to each other by, for example, an oxidation-resistant nickel feeder or the like by a method such as welding or brazing. be able to. In addition, when the inside of the cylinder and the outside of the vacuum chamber are joined to the flange by providing an airtight mechanism, the inside of the cylinder should be in a vacuum or inert gas atmosphere to create an environment where a thermocouple vulnerable to oxidation can be used. it can.

The thermal conductivity of the second ceramic sintered body 22 is preferably smaller than the thermal conductivity of the first ceramic sintered body 21. This is to prevent the heat of the first ceramic sintered body from escaping through the second ceramic sintered body. The thermal conductivity of the sintered body can be adjusted by increasing the average particle diameter of the first ceramic sintered body and decreasing the average particle diameter of the second ceramic sintered body.

The volume resistivity of the second ceramic sintered body is preferably 1 × 10 ¹⁴ Ωcm or more. This is because when a voltage is applied to the metal conductor embedded in the first ceramic sintered body, the leakage current flowing into the chamber through the second ceramic sintered body can be reduced.

The ceramics constituting the first and second ceramic sintered bodies can be aluminum nitride, aluminum oxide, silicon nitride, silicon carbide, or the like. The composition of each ceramic is determined according to the required characteristics. In particular, as the first ceramic sintered body, it is preferable to use a ceramic having a volume resistivity of 1 × 10 ⁸ Ω · cm or more at an operating temperature. As the material of the first ceramic sintered body having such physical properties, aluminum nitride or silicon nitride can be used. Of these, aluminum nitride is excellent in thermal conductivity, and is therefore suitable for ceramic heaters that require heat responsiveness and soaking.

Examples of the auxiliary component include additives for adjusting resistance and color tone and increasing strength in addition to the sintering aid. It is preferable to make these content less than 10 mass%. This is because it is difficult to suppress diffusion and grain growth when a large amount of subcomponents are contained. Therefore, it is preferable that 90 mass% or more of a main component is contained. As the sintering aid, in the case of aluminum nitride, rare earth element oxides such as yttrium oxide, calcium oxide and the like are used. In the case of silicon nitride, for example, yttrium oxide, aluminum oxide, magnesium oxide, or the like can be used.

As the metal conductor embedded in the first ceramic sintered body, a heat-resistant metal such as foil, plate, wire, mesh, or fibrous molybdenum or tungsten can be used. These function as heating resistors, electrostatic electrodes, or RF electrodes. Other metal conductors include temperature measuring elements such as thermocouples. For example, when aluminum nitride having excellent thermal conductivity is used as the ceramic, the firing temperature is 1600 to 2000 ° C., and as a thermocouple that can withstand this firing temperature, a JIS-regulated B thermocouple (Pt—Rh alloy, heat resistant temperature 1820) ° C or higher), R thermocouple, S thermocouple (Pt-Rh alloy / Pt, heat resistant temperature of 1760 ° C or higher) W-Re thermocouple (2400 ° C or higher), Ir-Rh thermocouple (Ir-40% Rh / Ir-50% Rh, heat resistant temperature of 2000 ° C. or higher) can be used. A sheath thermocouple may be used.

Next, a method for manufacturing a ceramic joined body will be described.

As the ceramic raw material of the ceramic sintered body, a commercially available ceramic powder can be used, and a granulated powder obtained by adding a binder to a ceramic powder to which an auxiliary component such as a sintering aid is added can be suitably used.

After the ceramic powder is molded by a known method such as uniaxial molding, pressure molding such as CIP, or casting, the obtained ceramic compact is sintered.

For the sintering, various methods such as atmospheric pressure sintering, gas pressure sintering, and hot press sintering in which the atmosphere is controlled to nitrogen or argon can be employed. However, the first ceramic sintered body is preferably produced by hot press sintering. In order to obtain a sintered body in which a metal conductor is embedded with high accuracy, hot press sintering is suitable.

In order to embed a metal conductor in the first ceramic sintered body with high accuracy, a plate-shaped formed body is formed using a high-precision press jig, a metal conductor is disposed on the formed body, and the metal A method in which ceramic powder is filled on a molded body on which conductors are arranged and press molding with a press jig is effective. Thereafter, by performing hot press sintering, a ceramic sintered body in which the metal conductor is embedded with high accuracy can be obtained.

The joining surface of the ceramic sintered body is preferably lapped and the flatness is controlled. It is preferable that the flatness of the bonding surface is 10 μm or less, and further, for example, when divided into 10 × 10 mm, the mutual difference in flatness of adjacent areas is 0.2 μm or less. Moreover, it is preferable that the surface roughness Rz (JISB0601-2001) of the joint surface is set to ½ or less of the average particle diameter. By adjusting the joining surface in this way, airtight joining with sufficient strength becomes possible.

The bonding temperature of the ceramic sintered body is set to a temperature that is equal to or higher than the temperature at which sintering shrinkage starts and does not generate creep. For example, the temperature is preferably 1400 to 1650 ° C. for aluminum nitride and 1100 to 1350 ° C. for silicon nitride. Also, the sintering temperature is lower than the sintering temperature of the first and second ceramic sintered bodies, more preferably lower than the sintering temperature. If it is such a range, it can join, suppressing the diffusion and grain growth of a subcomponent.

The pressure applied at the time of joining is preferably 1 to 20 MPa. By setting the temperature within such a range and sintering at the predetermined temperature, it is possible to obtain a bonded body with small deformation while suppressing the diffusion and grain growth of subcomponents.

Of the metal conductors, the thermocouple can be installed by forming a fine hole in the first ceramic sintered body by machining after firing and inserting a sheath thermocouple. In addition, wiring via via holes can be applied.

After joining, the main surface of the first ceramic sintered body in the joined body is subjected to planar polishing such as lapping and polishing to finish the surface on which the workpiece can be placed. At this time, since the metal conductor is embedded with high accuracy, the distance between the metal conductor and the main surface can be finished with high accuracy.

A method such as welding or brazing can be employed for the connection between the metal conductor, the feeder line, and the conductive line. At this time, the metal conductor embedded in the ceramic sintered body is exposed by grinding such as a machining center and connected to the exposed portion. For the connection, a metal conductor and a conductive wire or the like may be directly welded, or a connection terminal may be used and connected via a terminal.

Hereinafter, the present invention will be described with reference to examples and comparative examples.

[Joining of aluminum nitride sintered bodies (production Nos. 1 to 5)]
Here, an aluminum nitride disc (first ceramic sintered body) to which yttrium oxide embedded with metal was added and a cylinder (second ceramic sintered body) made of only aluminum nitride were joined.

[Production of disc]
A powder mixture composed of 97% by mass of aluminum nitride powder and 3% by mass of yttrium oxide powder was formed, filled in a mold, and subjected to uniaxial pressure treatment at a pressure of 9.8 MPa. As a result, a first layer having a diameter of 220 mm and a thickness of 10 mm was formed.

Next, a 190 mm diameter tungsten mesh (wire diameter: 0.1 mm, mesh size: 30 mesh) serving as an electrode was placed on the first layer. Subsequently, the previously formed powder mixture was filled on the electrode to a predetermined thickness to form a second layer. Then, hot press firing was performed at a pressure of 10 MPa at a firing temperature of 1800 and 1850 ° C. for a firing time of 2 hours to obtain a sintered body of φ220 × 15 mm. A part of this sintered body was cut out, and the average particle diameter was determined by SEM observation of the cut surface. The average particle size was calculated by the line intercept method. In the line intercept method, the average particle diameter was calculated by drawing a line segment intersecting at least 15 particles.

The sintered body was ground so that the distance from the surface to tungsten was 1 mm and 9 mm. Next, lapping was performed, and the flatness of a surface (main surface 21a in FIG. 4) having a distance of 1 mm from the surface to tungsten was set to 3 μm or less. Similarly, for the surface having a distance from the surface to tungsten of 9 mm (joint surface 21b in FIG. 4), the flatness was set to 10 μm or less, and the surface roughness Rz was set to ½ or less of the average particle diameter. Further, when the joint surface was divided into 10 × 10 mm, the mutual difference in flatness of adjacent areas was set to 0.2 μm or less.

[Cylinder production]
Aluminum nitride granules were obtained by adding IPA, an organic binder, and a plasticizer to aluminum nitride powder as a raw material, followed by mixing and spray-drying. This granule was CIP-molded, fired at normal pressure with a firing temperature of 1900 and 2000 ° C. and a firing time of 6 hours, and then cylindrical processing was performed to obtain a cylinder with an outer diameter of 70 mm, an inner diameter of 30 mm, and a length of 120 mm. One end face of this cylinder was cut, and the average particle diameter was determined by SEM observation.

Lapping was performed on one end surface of the cylinder (end portion 22a in FIG. 4) so that the flatness was 10 μm or less and the surface roughness Rz was 1/2 or less of the average particle diameter. Further, when one end face was divided into 10 × 10 mm, the mutual difference in flatness of adjacent areas was set to 0.2 μm or less.

[Joint and evaluation]
The joining surface of the disc and the one end surface of the cylinder were superposed and joined by hot press firing. The flatness was measured with a laser interferometer before and after joining the main surfaces of the disks. Further, the air density of the joint was measured with a helium leak detector by a bombing method. Further, the presence or absence of grain growth of the sintered body after bonding was measured by SEM observation of the cut surface, and the presence or absence of diffusion of subcomponents was measured by EPMA. For the measurement of the average particle size, the average particle size at each position was determined by the line intercept method along the bonding interface every 15 μm from the position of 15 μm from the bonding interface.

As a comparative example, a joined body using a joining material was produced (Production No. 6). The same disk and cylindrical aluminum nitride sintered body as described above were used. The calcium carbonate powder was blended so as to be 28 mass% in terms of calcium oxide, the yttrium oxide powder was 26 mass%, and the aluminum oxide powder was 46 mass%, and a binder and a plasticizer were added and mixed to obtain a paste. The paste was applied to the joint surface of the disc and one end surface of the cylinder, self-leveled, and then degreased at 500 ° C. These surfaces were combined and joined under the conditions shown in Table 1.

[Joining of silicon nitride sintered body (production Nos. 7 and 8)]
In the bonding of the silicon nitride sintered body, a disk and cylinder bonding test was performed without embedding the metal conductor. Needless to say, embedding of a metal conductor can also be applied to bonding of silicon nitride sintered bodies.
[Production of disc]
94% by mass of silicon nitride powder, 3% by mass of yttrium oxide powder, 3% by mass of magnesium hydroxide powder in terms of magnesium oxide, IPA, organic binder and plasticizer are added, mixed, and spray-dried As a result, silicon nitride granules for disks were obtained. This granule was CIP-molded and subjected to normal pressure firing at a firing temperature of 1700 ° C. and a firing time of 6 hours, thereby obtaining a disc having a diameter of 200 × 10 mm. A part of this sintered body was cut out, and the average particle diameter was determined by SEM observation of the cut surface.

The joint surface of this disk was ground and lapped so that the flatness was 10 μm or less and the surface roughness Rz was ½ or less of the average particle diameter. Further, when the joint surface was divided into 10 × 10 mm, the mutual difference in flatness of adjacent areas was set to 0.2 μm or less. The main surface of this disk was lapped to a flatness of 5 μm or less.

[Cylinder production]
By mixing 94% by mass of silicon nitride powder, 3% by mass of yttrium oxide powder, and 3% by mass of aluminum oxide powder, adding IPA, organic binder and plasticizer, mixing, spray drying and drying Silicon nitride granules were obtained. This granule was CIP-molded and fired at normal pressure with a firing temperature of 1700 ° C. and a firing time of 6 hours, and then cylinder processing was performed to obtain a cylinder with an outer diameter of 70 mm, an inner diameter of 30 mm, and a length of 120 mm. One end face of this cylinder was cut, and the average particle diameter was determined by SEM observation. One end face of this cylinder was ground and lapped so that the flatness was 10 μm or less and the surface roughness Rz was ½ or less of the average particle diameter. Further, when one end face was divided into 10 × 10 mm, the mutual difference in flatness of adjacent areas was set to 0.2 μm or less.

[Joint and evaluation]
The joining surface of the disc and one end surface of the cylinder were overlapped and joined under the conditions shown in Table 1. The flatness was measured with a laser interferometer before and after joining the main surfaces of the disks. Further, the air density of the joint was measured with a helium leak detector by a bombing method. Further, the presence or absence of grain growth of the sintered body after bonding was measured by SEM observation of the cut surface, and the presence or absence of diffusion of subcomponents was measured by EPMA. For the measurement of the average particle size, the average particle size at each position was determined by the line intercept method along the bonding interface every 15 μm from the position of 15 μm from the bonding interface.

[Joint aluminum oxide sintered body (production No. 9)]
In joining aluminum oxide sintered bodies, a joining test of a disk and a cylinder was performed without embedding a metal conductor. Needless to say, embedding of a metal conductor can also be applied to bonding of aluminum oxide sintered bodies.

[Production of disc]
Aluminum oxide granules for disk were obtained by adding 99.99% pure aluminum oxide powder as a raw material, IPA, an organic binder and a plasticizer, mixing, and spray drying. This granule was CIP-molded and subjected to normal pressure firing at a firing temperature of 1500 ° C. and a firing time of 6 hours, thereby obtaining a disc having a diameter of 200 × 10 mm. A part of this sintered body was cut out, and the average particle diameter was determined by SEM observation of the cut surface. The main surface of this disk was ground and lapped so that the flatness was 5 μm and the surface roughness Rz was ½ or less of the average particle diameter. Further, when the joint surface was divided into 10 × 10 mm, the mutual difference in flatness of adjacent areas was set to 0.2 μm or less. The joining surface on the back side of the main surface was lapped to a flatness of 3 μm.

[Cylinder production]
Add 95% pure aluminum oxide (the balance is 3% by weight silicon oxide, 1% by weight calcium oxide, 1% by weight magnesium oxide), IPA, organic binder and plasticizer, and mix and spray dry. Thereby, the aluminum oxide granule for cylinders was obtained.
The granules were CIP-molded, fired at normal pressure with a firing temperature of 1600 ° C. and a firing time of 6 hours, and then subjected to cylindrical processing to obtain a cylinder with an outer diameter of 70 mm, an inner diameter of 30 mm, and a length of 120 mm. One end face of this cylinder was cut, and the average particle diameter was determined by SEM observation. One end face of this cylinder was ground and lapped so that the flatness was 2 μm and the surface roughness Rz was ½ or less of the average particle diameter. Further, when one end face was divided into 10 × 10 mm, the mutual difference in flatness of adjacent areas was set to 0.2 μm or less.

[Joint and evaluation]
The joining surface of the disc and one end surface of the cylinder were overlapped and joined under the conditions shown in Table 1. The flatness was measured with a laser interferometer before and after joining the main surfaces of the disks. Further, the air density of the joint was measured with a helium leak detector by a bombing method. Further, the presence or absence of grain growth of the sintered body after bonding was measured by SEM observation of the cut surface, and the presence or absence of diffusion of subcomponents was measured by EPMA. For the measurement of the average particle size, the average particle size at each position was determined by the line intercept method along the bonding interface every 15 μm from the position of 15 μm from the bonding interface.

In Production Nos. 1 to 3, the change in flatness of the main surface before and after joining was small and the airtightness of joining was high. As a result of investigating the presence or absence of subcomponent diffusion and grain growth in these joints, no diffusion of magnesium and yttrium was observed for the subcomponent, and the average grain size was constant at each measurement position, and grain growth. Was not recognized. In the measurement of the diffusion of the subcomponents and the average particle diameter, the results as shown in FIG. 2 were obtained.

Production No. 4 could not be joined because the joining temperature was low. In Production No. 5, diffusion of subcomponents and grain growth were observed. The flatness of the main surface was significantly deteriorated and greatly deformed. In the production No. 6 using the bonding material, the deformation was significant. From the measurement result of EPMA, it was confirmed that the bonding material component diffused into the sintered body.

In Production Nos. 7 to 9, the change in flatness of the main surface before and after joining was small, and the airtightness of joining was high. As a result of examining the diffusion of subcomponents and the presence or absence of grain growth in these joined bodies, no diffusion of yttrium, aluminum and magnesium, and silicon, calcium and magnesium was observed for the subcomponents. The diameter was constant and no grain growth was observed. In the measurement of the diffusion of the subcomponents and the average particle diameter, the results as shown in FIG. 2 were obtained.

10, 20 Bonded body 11, 21 First ceramic sintered body 12, 22 Second ceramic sintered body 21a Main surface 11a, 21b Bonded surface 12a, 22a End

Claims (8)

A ceramic joined body in which the first ceramic sintered body and the second ceramic sintered body are joined without using a joining material,
The first and second ceramic sintered bodies have one of aluminum nitride, aluminum oxide and silicon nitride as a main component in common with each other,
The ceramic sintered body of either one or both of the first and second contains a subcomponent,
The thermal conductivity of the second ceramic sintered body is smaller than the thermal conductivity of the first ceramic sintered body,
A ceramic joined body, wherein the subcomponent of one ceramic sintered body is not diffused into the other ceramic sintered body.   The ceramic joined body according to claim 1, wherein the first ceramic sintered body and the second ceramic sintered body do not show grain growth during joining.   The ceramic joined body according to claim 1 or 2, wherein the first ceramic sintered body has a metal conductor embedded therein. The first ceramic sintered body has a plate shape having a main surface on which a substrate is placed;
The ceramic according to any one of claims 1 to 3, wherein the second ceramic sintered body has a cylindrical shape in which an end portion is joined to a surface on the back side of the main surface of the first ceramic sintered body. Joined body. The ceramic joined body according to claim 3 , wherein the metal conductor is a heating resistor, an electrostatic electrode, or an RF electrode. A ceramic heater using the ceramic joined body according to any one of claims 3 to 5 . An electrostatic chuck using the ceramic joined body according to claim 3 . A susceptor using the ceramic joined body according to any one of claims 3 to 5 .

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