JPH06151320A - Method of combining terminal of ceramics heater with power supply member - Google Patents

Abstract

PURPOSE:To easily combine the terminal of a ceramics heater with an electric power supply member, in a short time, at a low cost, and prevent generation of deterioration in a resistance heating element at the time of combination. CONSTITUTION:A resistance heating element 5 is buried in a ceramics substratun 4. A terminal 3 is buried in the ceramics substratum 4, and the resistance heating element 5 is connected with the terminal 3. A part of the surface of the terminal 3 is exposed from the ceramics substratum 4. An intermediate layer 2 containing metal is formed on the surface 3a of the terminal 3, and an electric power supply member 1 is brought into contact with the intermediate layer 2. By generating discharge between the terminal 3 and the electric power supply member 1, the metal is partly fused, so that the terminal 3 is bonded to the electric power supply member 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a terminal of a ceramic heater and a power supply member.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus that requires a super clean state, there are known some heating apparatuses for heating a semiconductor wafer in a state of being in contact with a corrosive gas. Of these, the heater with a stainless steel outer shell is corroded by corrosive gas,
Not suitable for the production of high-purity semiconductors. Further, the so-called indirect heating method has a problem that heat loss is large and it takes time to raise the temperature.

In order to solve this problem, the applicant of the present invention has proposed a ceramics heater in which a resistance heating element is embedded in a disc-shaped dense ceramics in Japanese Patent Laid-Open No. 4-87179. The reason why the heater has a disk shape is as follows.

In the case of the conventional stainless steel heater, the heating surface of the semiconductor wafer and the terminal of the resistance heating element are largely separated from each other, and the terminal and the external power supply cable are connected outside the container of the semiconductor manufacturing apparatus. . Therefore, the heated part is exposed to the high temperature and corrosive atmosphere, but the connecting part between the terminal and the power supply cable is not exposed to such high temperature and corrosive atmosphere.

On the other hand, when the ceramic heater is manufactured, the resistance heating element is put into the ceramic powder and is molded, so that the ceramic heater must have a simple shape such as a disk shape.
The same applies because hot press firing is performed in the firing stage. In addition, there is a fired altered layer called black skin on the surface of the fired body after firing, and it is necessary to remove this altered layer by processing. At this time, a grinding process with a diamond grindstone is required, and the processing cost is high if the shape of the fired body is complicated. As described above, the ceramic heater in which the resistor is embedded must have a simple shape such as a disk shape because of difficulty in manufacturing. Therefore, it is structurally difficult to expose the terminals of the heater to the outside of the semiconductor manufacturing container, and the terminals are inevitably exposed to high temperature and corrosive gas.

In order to solve this problem, the present applicant has disclosed in Japanese Patent Laid-Open No. 4-87179 a method of connecting a terminal of a ceramic heater and a power supply member by a heat and corrosion resistant connection. Specifically, there were the following binding methods. Mechanically connecting the terminal and the power supply member by a threading method. Joining the terminal and the power supply member with a brazing material. Between the terminal and the electrode supply member, a powder or foil of a refractory metal such as Mo or W is interposed and heated to a high temperature for diffusion bonding. On the end face of the terminal or the end face of the power supply member, plating, CVD,
Forming a coating layer by thermal spraying, and then diffusion welding or friction welding. Welding.

[0007]

However, in the case of the thread cutting method, since the terminal and the power supply member are made of a hard and brittle refractory metal such as tungsten, it is impossible to process them by a normal die. Therefore, the screw was formed by the electric discharge machining method. However, this method is very expensive and takes a long time. Further, since the vicinity of the terminal is exposed to high temperature for a long time, the resistance heating element may be deteriorated or broken.

[0008] When brazing is used, the maximum is 600.
Sufficient bonding strength could be maintained only up to about ° C. Therefore, it may not be suitable for semiconductor applications where use at a high temperature of 1000 ° C. or higher is expected.
Further, when exposed to high temperatures, brazing components such as magnesium, titanium, and copper may be vaporized, causing a semiconductor defect.

When diffusion bonding is performed using metal powder or metal foil, in the case of tungsten, it is necessary to perform heat treatment at a high temperature of 1700 ° C. or higher for about 2 to 3 hours. As a result, the resistance heating element may be deteriorated or broken, and the ceramics may be deteriorated.

In the method of forming the coating layer by plating, CVD, thermal spraying, etc., the coating layer may be separated from the end face. In addition, the CVD method is extremely expensive.
A method was also studied in which the power supply member and the terminal were brought into close contact with each other, an electric current was applied in this state to melt the vicinity of the interface between both members, and welding was performed. In this case, the vicinity of the end surface of the power supply member was slightly melted, but the terminal side was not melted and both members were not joined. This is probably because heat escapes from the terminals to the ceramics having a relatively large specific heat.

An object of the present invention is to make it possible to easily and cost-effectively connect the terminals of the ceramic heater and the power supply member in a short time. First, it is necessary to prevent deterioration of the resistance heating element and the like.

[0012]

SUMMARY OF THE INVENTION The present invention is directed to a ceramic substrate, a resistance heating element embedded in the ceramic substrate, a resistance heating element connected to the resistance heating element, embedded in the ceramic substrate and part of the surface. A method of connecting a power supply member for supplying power to the resistance heating element to the terminal after preparing a ceramics heater having an exposed terminal, wherein an intermediate layer containing metal is formed on the surface of the terminal. Then, the power supply member is brought into contact with the intermediate layer, and the metal is melted by discharging between the terminal and the power supply member, and the terminal and the power supply member are joined together. The present invention relates to a method of connecting a terminal and a power supply member.

[0013]

First, one embodiment of a ceramic heater to which the present invention can be applied will be described. FIG. 1 is a sectional view schematically showing a state in which a ceramics heater is attached to a thermal CVD device.

Gas for thermal CVD is supplied from the gas supply hole 20 in the direction of arrow A into the container 18 used for semiconductor manufacturing CVD, and the air inside is sucked from the suction hole 19 by a vacuum pump as shown by arrow B. Is discharged. The flange 10 is attached so as to cover the upper opening of the container 18, and the water cooling jacket 17 is attached to the flange 10. The O-ring 16 seals between the flange 10 and the container 18. The flange 10 constitutes the ceiling surface of the container. The case 6 is attached to the lower surface of the flange 10, and the ceramics heater is supported inside the case 6.

A resistance heating element 5 is embedded inside the disk-shaped ceramic substrate 4. In this example, the resistance heating element 5 is embedded in a substantially spiral shape when seen in a plan view. The dimension of the wafer heating surface 4b of the disk-shaped ceramic substrate 4 is set so that a semiconductor wafer can be installed. A terminal 3 (13), which will be described later, is connected to the end of the resistance heating element 5 in the vicinity of the center of the disk-shaped ceramic substrate 4 and the peripheral portion. A power supply member 1 (11) described later is connected to each terminal 3 (13), and the cable 7 is taken out of the container. Electric power is supplied to the resistance heating element 5 via the pair of cables 7, the power supply member 1 (11), and the terminal 3 (13).

The hollow sheath 8 is inserted into the container 26 through the through hole of the flange 10. The tip of the hollow sheath 8 is joined to the back surface 4a side of the ceramic base 4. A thermocouple 9 with a stainless sheath is inserted inside the hollow sheath 8. An O-ring is provided between the hollow sheath 8 and the flange 10 to prevent entry of air.

As can be seen from FIG. 1, since the connecting portion between the terminal 3 (13) and the power supply member 1 (11) is located inside the container 18, it is inevitably exposed to high temperature and corrosive gas. A method of forming the joint portion and the like will be described with reference to FIGS.

As shown in FIG. 2, a columnar terminal 3, for example, is embedded so that the surface 3a is exposed on the rear surface 4a side of the ceramic substrate 4. In this example, the terminal 3 is provided with a small protrusion 3b, and the end of the resistance heating element 5 is a small protrusion 3b.
Being pinched by. An intermediate layer 2 containing a metal powder capable of diffusing is formed on the terminal 3 and the power supply member 1 so as to cover the surface 3a. The end surface 1a of the power supply member 1 is brought into contact with the intermediate layer 2.

The inventor tried to apply a voltage between the power supply member 1 and the terminal 3 in this state to cause a discharge between them. Then, it was found that the intermediate layer 2 was partially dissolved and disappeared, and the power supply member 1 and the terminal 3 were joined as shown in FIG. This bonding strength was sufficiently high, and electrical contact was satisfactory.

According to this method, the power supply member 1 and the terminal 3 can be connected to each other in an extremely short time, simply and at low cost. Moreover, since it can be performed in a short time, the resistance heating element is not deteriorated or broken, and the ceramics are not deteriorated or altered.

As the material of the disk-shaped ceramic substrate 4, silicon nitride, sialon, aluminum nitride or the like is preferable. Silicon nitride and sialon are preferable in terms of thermal shock resistance. Further, aluminum nitride has high corrosion resistance against a fluorine-based corrosive gas such as NF ₃ .

The materials for the resistance heating element 5, the terminal 3 and the power supply member 1 are preferably refractory metals such as tungsten, molybdenum, platinum and nickel, and alloys thereof may also be used. The metal contained in the intermediate layer 2 is preferably in the form of powder, but may be a foil or a small piece as long as it can be dissolved by electric discharge. Further, when the metal forming the terminal 3 and the power supply member 1 is a simple substance, it is preferable to use the same metal. The metal that constitutes the terminal 3 and the power supply member 1
When the metal forming the above is an alloy, it is preferable that the above metal is formed of this alloy. In this case, it is preferable to match the composition ratios of the alloys.

The average particle size of the powder is preferably 5 μm or less. There are several methods for forming the intermediate layer 2. The above powder can be dispersed in an organic solvent, and this dispersion can be applied onto the terminals 3. As the organic solvent, low boiling point organic solvents such as acetone, methanol, ethanol and hexane are preferable. When water or the like is used, the metal is oxidized. Further, an organic binder can be mixed in this dispersion liquid. As another method, the surface 3
The intermediate layer 2 can be formed by thinly printing the above powder on a.

The discharge between the power supply member 1 and the terminal 3 is
It is preferably performed in a non-oxidizing atmosphere, more preferably in an inert gas such as argon or nitrogen.

Specific experimental results of the method shown in FIGS. 2 and 3 will be described. A ceramic heater as shown in FIGS. 1 and 2 was produced. The material of the disk-shaped ceramic substrate 4 is silicon nitride, and the resistance heating element 5, the terminal 3, the power supply member 1
The material was tungsten. Tungsten having an average particle size of 1 μm was dispersed in an organic solvent, and this dispersion was applied on the surface 3a to form the intermediate layer 2. The power supply member 1 was fixed on this, vacuum suction was carried out, and argon gas was filled into the apparatus. At this time, the gas was slowly replaced in order to prevent the powder from being scattered by the air flow. 100A, 10
When a power of several V was supplied and a discharge was generated between the power supply member 1 and the terminal 3, both members were instantly joined.

With respect to this heater, electric power is supplied through a pair of electric power supply members 1 to raise the temperature from room temperature to 1000 ° C. at a rate of 10 ° C./minute, hold at 1000 ° C. for 5 minutes, and hold at 500 ° C. at 10 ° C./minute. Decrease the temperature to ℃, 50
It was naturally cooled below 0 ° C. A stable power supply was possible through this electric heating process.

In the example shown in FIG. 4, the power supply member 1
For example, a circular protrusion 11a is provided at the end of 1. on the other hand,
The resistance heating element 5 was connected to the small protrusion 13b of the terminal 13, and a circular recess 13c, for example, was provided on the opposite side of the small protrusion 13b. The intermediate layer 2 containing the above powder was provided in the recess 13c and the surface 13a, and the protrusion 11a was inserted into the recess 13c. At this time, the power supply member 11 and the terminal 13 were prevented from directly contacting each other. In this state, electric discharge was performed and the power supply member 11 and the terminal 13 were joined. In this embodiment, the power supply member 1
The connection between 1 and the terminal 13 became stronger.

In the example shown in FIG. 5, the hollow sheath 21
The thermocouple 9 is inserted into the cavity 21b of the hollow sheath 21
The thermocouple 9 is located in the tip portion 21a of the. The hollow sheath 21 is made of a refractory metal such as tungsten, molybdenum, or platinum, and functions as a power supply member. Recess 13
The intermediate layer 2 is formed in c, the tip 21a is inserted into the recess 13c, and the electric discharge is generated between the power supply member 21 and the terminal 13. The intermediate layer may not be provided on the surface 13a. An insulating layer is provided between the thermocouple 9 and the power supply member 21.

[0029]

According to the present invention, when the terminal of the ceramics heater and the power supply member are joined, an intermediate layer containing metal is formed on the surface of the terminal, and the power supply member is brought into contact with the intermediate layer. It was possible to partially melt the metal and to bond the terminal and the power supply member by discharging between the power supply member and the power supply member. This bonding strength was sufficiently high, and electrical contact was satisfactory.

According to this method, the power supply member and the terminal can be connected in a very short time, simply and at low cost. Moreover, since it can be performed in a short time, the resistance heating element is not deteriorated or broken, and the ceramics are not deteriorated or altered.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a state in which a ceramics heater is installed in a container 18.

FIG. 2 is a cross-sectional view showing a state where the power supply member 1 is in contact with the intermediate layer 2.

FIG. 3 is a cross-sectional view showing a state in which a power supply member 1 and a terminal 3 are joined together.

FIG. 4 is a cross-sectional view showing a state before the power supply member 11 and the terminal 13 are joined together.

5 is a cross-sectional view showing a state before joining the power supply member 21 and the terminal 13. FIG.

[Explanation of symbols]

 1,11,21 Power supply member 2 Intermediate layer 3,13 terminal 4 Disk-shaped ceramic substrate 5 Resistance heating element 7 Power supply cable

Claims (1)

[Claims] 1. A ceramic substrate, a resistance heating element embedded in the ceramic substrate, and a terminal connected to the resistance heating element, embedded in the ceramic substrate, and having a part of the surface exposed. A method of connecting a power supply member for supplying power to the resistance heating element to the terminal after preparing a ceramics heater, wherein an intermediate layer containing a metal is formed on a surface of the terminal, and the power supply member is formed as follows. Contacting the intermediate layer, and by melting the metal by causing a discharge between the terminal and the power supply member, to join the terminal and the power supply member,
A method for connecting a terminal of a ceramic heater and a power supply member.