JP2662360B2 - Manufacturing method of ceramic heater and ceramic heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic heater which can be used in various semiconductor manufacturing apparatuses, etching apparatuses, and the like, and a ceramic heater.

[0002]

2. Description of the Related Art Conventionally, as a heat source in a semiconductor manufacturing apparatus, a so-called stainless steel heater or an indirect heating type has been generally used. However, when these heat sources are used, there has been a problem that particles are generated due to the action of the halogen-based corrosive gas, and heat efficiency is poor.
In order to solve such a problem, the present inventor has proposed a ceramic heater in which a wire made of a high melting point metal is embedded in a disk-shaped base made of dense ceramics. The wire is spirally wound inside the disc-shaped base, and terminals are connected to both ends of the wire.
It has been found that such a ceramic heater has excellent characteristics especially for semiconductor production.

[0003]

However, it has been found that some problems also occur in such a disk-shaped ceramic heater, particularly for manufacturing reasons. That is,
In order to manufacture the above-described ceramic heater, first, a wire or wire of a high melting point metal is wound to obtain a wound body, and terminals (electrodes) are bonded to both ends of the wire.
On the other hand, ceramic powder is charged into a press molding machine and pre-molded until a certain degree of hardness is obtained. At this time, continuous concave portions or grooves are provided on the surface of the preform along a predetermined planar pattern. Then, the wound body is accommodated in the concave portion, and the ceramic powder is further filled thereon. Then, the ceramic powder is uniaxially pressed to form a disk-shaped molded body, and the disk-shaped molded body is subjected to hot press sintering.

However, when arranging the above-mentioned wound body on the preformed body along a predetermined planar pattern, it is necessary to manually insert the wound body along the concave portion of the preformed body. This is a very complicated task. In this case, a positional shift occurs and a shape collapse occurs. As a result, the position of the resistance heating element is still not constant inside the ceramic base after sintering.
A portion having a high calorific value and a portion having a low calorific value occur. As a result,
The temperature of the heating surface of the heater becomes uneven, and the heating characteristics of the heater are not constant. If the temperature of the heating surface of the heater becomes uneven, the thickness of the semiconductor film becomes non-uniform, especially in the case of a semiconductor manufacturing apparatus, which causes a semiconductor defect.

An object of the present invention is to embed the above-mentioned resistance heating element in a ceramic molded body so that the burying operation can be performed easily and in a short time, and to prevent displacement of the embedment position of the resistance heating element. It is to be.

[0006]

Means for Solving the Problems According to the present invention, a winding body formed by winding a high melting point metal wire is held in a predetermined planar pattern, and then the primary recrystallization starting temperature of the high melting point metal is obtained. In the following, the wound body is heat-treated in a non-oxidizing atmosphere to obtain a resistance heating element, the resistance heating element is buried inside the ceramic molded body, and then the ceramic molded body is sintered to form a ceramic base. The present invention relates to a method for manufacturing a ceramic heater, which obtains a ceramic heater having a resistance heating element embedded in a predetermined planar pattern inside the ceramic base.

Further, the present invention is a ceramic heater comprising a ceramic base and a resistance heating element embedded in the ceramic base along a predetermined planar pattern, wherein the resistance heating element has a high melting point. Resistance heating obtained by heat treatment in a non-oxidizing atmosphere at a temperature lower than the primary recrystallization start temperature of the refractory metal while holding a wound body formed by winding a metal wire along a predetermined planar pattern. The present invention relates to a ceramic heater which is a body.

[0008]

Hereinafter, an embodiment of the present invention will be described. First, a wire of a high melting point metal is wound to obtain a wound body 1 having, for example, a shape as shown in FIG. In this example, the wound body 1 in which the wire is wound in a spiral shape is used, but the shape of the spiral in the width direction can be a circle, an ellipse, a quadrilateral, or the like. In the stage of FIG. 1A, the pitch of the spirally wound body 1 in the helical length direction is relatively small.

Next, the wound body is held in a predetermined planar pattern. As this means, any method can be adopted, but it is desirable to house it in a groove provided in a mold along this pattern. At this stage, there are roughly two methods. In the first method, a winding body 2 to be processed having a planar pattern as shown in FIG. The pattern made in this example is
For two-zone heater. That is, of the three cylindrical terminals 3, one is connected to the outer end of the wound body 2 to be processed, one is connected to the inner end of the wound body 2, and the other is these. It is connected between. In the wound body 2 to be processed, the outermost peripheral portion 2a has a dense spiral pitch, and the intermediate portion 2b between the outermost peripheral portion 2a and the inner terminal 3 has a spiral spiral pitch. Circumference part 2c
Has a relatively dense spiral pitch.

A mold 4 as shown in FIGS. 2A and 2B is prepared. On the front side of the mold 4, a groove 4a having a substantially rectangular cross section in the width direction is formed. The planar pattern of the groove 4a is
The pattern is the same as that of the wound body 2 to be processed. Then, the wound body 2 to be processed in FIG. 1B is accommodated in the groove 4a.

In the second method, the wound body 1 shown in FIG.
Is stretched, and then sequentially housed in the groove 4a of the mold 4,
Thereby, the wound body 2 to be processed is formed in the groove 4a. According to the second method, as compared with the first method, it is possible to save the trouble of transferring the wound body 2 to be processed from the jig to the mold 4. However, on the other hand, since the mold 4 is subjected to a heat treatment described later, the cost is higher than that of the jig. According to the first method, the operation rate of the high-cost mold 4 is higher than that of the second method.

Next, the roll 2 to be treated is heat-treated in a non-oxidizing atmosphere at a temperature not higher than the primary recrystallization start temperature of the high melting point metal constituting the roll 1 to obtain a resistance heating element. Then, the resistance heating element is embedded in the ceramic molded body, and then the ceramic molded body is sintered. At this stage, in this embodiment, the following method was used.

FIGS. 3A to 3D are cross-sectional views schematically showing a procedure for manufacturing a disc-shaped ceramic molded body. First, a ceramic powder is filled in the upper part of the lower mold 6A (inside of the frame 5), and press-formed once to obtain a preformed body 7. Drill holes to accommodate the terminals, and place the resistance heating element 12 on the preform 7
Is installed so that the terminal 3 is located below the resistance heating element 12. The ceramic powder 8 is filled on the resistance heating element 12. Next, as shown in FIG. 3C, the ceramic powder is uniaxially pressed with the upper mold 6B and the lower mold 6A to obtain a ceramic molded body 9. Next, as shown in FIG. 3D, the lower mold 6A is raised and the ceramic molded body 9 is taken out.

Next, the ceramic molded body 9 is sintered to densify the ceramic, thereby obtaining a disk-shaped ceramic base. The back side of the ceramic base is ground to obtain a ceramic heater. Most preferably, the ceramic molded body 9 is sintered by a hot press method.
After sintering under normal pressure or pre-sintering under normal pressure, sintering may be performed by hot isostatic pressing.

According to the above-described embodiment, the wound body 2 to be processed
Is housed in the groove 4a and is subjected to the heat treatment, so that the planar pattern of the resistance heating element is given shape retention. Therefore, when the resistance heating element 12 is placed on the preform 7, the resistance heating element can be easily and quickly transferred. Since the wound body 2 described above is three-dimensionally deformed, it has conventionally been very difficult to install the wound body 2 on the preform 7 while maintaining this planar pattern.
Moreover, even when the resistance heating element 12 is installed and after the installation,
The displacement of the buried position of the resistance heating element 12 was reduced, and the uniformity of the heating surface of the ceramic heater was also improved.

Further, by subjecting the wound body 2 to be heat-treated in a non-oxidizing atmosphere, it is possible to suppress deterioration and deterioration of the wound body 2 to be processed.

Examples of the dense ceramic constituting the base include silicon nitride, aluminum nitride, sialon, and the like. According to the study of the present inventors, the thermal shock resistance of the heater is high when silicon nitride is used. Also, when aluminum nitride is used, a high corrosion resistance effect can be obtained with respect to a halogen-based corrosive gas. As the high melting point metal constituting the resistance heating element 12, tungsten, molybdenum, platinum, or an alloy thereof is preferable.

The wound body 2 to be processed is heat-treated at a temperature equal to or lower than the primary recrystallization start temperature of the refractory metal constituting the wound body 2. If the heat treatment temperature exceeds the secondary recrystallization start temperature, the resistance heating element 12 becomes brittle.

FIG. 4 shows the relationship between the heat treatment temperature and the strength of the tungsten wire. Heat treatment temperature is about 1200 ℃
If it exceeds, a decrease in tensile strength has begun. Therefore, it is considered that the vicinity of 1200 ° C. is the primary recrystallization start temperature. At around 1500 ° C., primary recrystallization is almost complete.
Then, in the region where the heat treatment temperature is about 2000 ° C. to about 2200 ° C., the tensile strength is significantly reduced again. From this, it is considered that the secondary recrystallization start temperature is about 2000 ° C. Actually, when observing the metal structure after heat treatment, the heat treatment temperature was 21
In the case of 50 ° C., the fibrous structure has been cut and secondary recrystallization has occurred. When the heat treatment temperature is 2350 ° C., only the secondary recrystallization structure is obtained, and the secondary recrystallization has been completed.

Further, the strength of the resistance heating element 12 after the heat treatment is preferably higher, and the deterioration and deterioration due to the heat treatment must be minimized. In this sense, the heat treatment is preferably performed at a temperature lower than the primary recrystallization start temperature of the refractory metal. In addition, in order to impart shape retention to the resistance heating element 12, the heat treatment is preferably performed at a temperature of 800 ° C. or higher. When the refractory metal is tungsten, if the above heat treatment is performed at 800 to 900 ° C., sufficient shape retention can be obtained and the resistance heating element does not deteriorate.

In the present invention, the roll is heat-treated in a non-oxidizing atmosphere. As such a non-oxidizing atmosphere, 10 ^-3
Vacuum below torr, hydrogen atmosphere, and inert gas atmosphere such as nitrogen and argon are included.

As the material of the mold 4, a material that is not easily deteriorated or deteriorated by the above heat treatment is used. Specifically, ceramics such as alumina, silicon carbide and silicon nitride, and high melting point metals such as stainless steel, nickel and tungsten are preferable.

Hereinafter, specific experimental results will be described. The heat treatment of the wound body 2 is performed by the method shown in FIGS. 1 and 2, a disc-shaped ceramic molded body is produced by the method shown in FIG. 3, and this is sintered to form a disc for 8 inches. A ceramic heater was obtained. However, the mold 4 was formed from high-purity alumina ceramics. In addition, the atmosphere when heat-treating the wound body 2 to be treated was as shown in Table 1, and the heat treatment temperature was changed as shown in Table 1. The heat treatment time was 1 hour. Silicon nitride powder was used as the material of the ceramic molded body 9, and a tungsten wire was used as the material of the wound body 1. The thickness of this tungsten wire is φ0.
The winding pitch was 2.5 mm.

Then, the surface state of the resistance heating element after heat treatment and the presence or absence of embrittlement were confirmed. Further, the resistance heating element was transferred from the mold 4 onto the preform and placed thereon. Then, after molding and sintering as shown in FIG. 3, the position of the resistance heating element in the ceramic base was examined by X-ray, and the positional deviation from the target position was measured.
Also, the same measurement as above was performed when the above heat treatment was not performed. Table 1 shows the results.

[0025]

[Table 1]

When the present invention was not applied, the displacement of the resistance heating element was large, and the uniformity of the heating surface was impaired. According to the present invention, these points have been greatly improved. Moreover, it was confirmed that when the resistance heating element was heat-treated according to the present invention, the resistance heating element could be easily and quickly installed on the preform 7.

[0027]

According to the present invention, a wound body is accommodated in a groove provided in a mold along a predetermined planar pattern, and primary recrystallization of a high melting point metal constituting the wound body is performed. Since the wound body is heat-treated at a temperature equal to or lower than the starting temperature, shape retention is imparted to the planar pattern of the resistance heating element. Therefore, when the resistance heating element is embedded in the ceramic molded body, the resistance heating element can be easily and quickly transferred. Since the wound body described above deforms three-dimensionally,
Conventionally, embedding in a ceramic molded body while maintaining this planar pattern has been a very difficult task. In addition, even when the resistance heating element is buried and after the resistance heating element is buried, the displacement of the buried position of the resistance heating element is reduced, thereby improving the uniformity of the heating surface of the ceramic heater. Further, by performing heat treatment on the wound body in a non-oxidizing atmosphere, deterioration and deterioration of the wound body can be suppressed.

[Brief description of the drawings]

FIG. 1A is a front view showing a wound material 1;
(B) is a plan view schematically showing the wound body 2 to be processed.

FIG. 2A is a cross-sectional view showing a mold 4, and FIG. 2B is a plan view showing a state where a wound body 2 to be processed is accommodated in a groove 4a of the mold 4. FIG.

FIGS. 3 (a), (b), (c), and (d) are cross-sectional views schematically showing a procedure for manufacturing a disc-shaped ceramic molded body 9. FIG.

FIG. 4 is a graph showing a relationship between the strength of a tungsten wire and a heat treatment temperature.

[Explanation of symbols]

1 roll material, 2 rolls to be processed, 3 terminals, 4
Mold, 4a groove, 7 preform, 9 disc-shaped ceramics, 12 resistance heating element

Claims (2)

(57) [Claims] 1. A wound body formed by winding a wire of a high melting point metal is held in a predetermined planar pattern, and is then placed in a non-oxidizing atmosphere at a temperature lower than the primary recrystallization start temperature of the high melting point metal. The wound body is heat-treated to obtain a resistance heating element, the resistance heating element is buried inside the ceramic molded body, and then the ceramic molded body is sintered to form a ceramic base and a predetermined inside of the ceramic base. A method for manufacturing a ceramic heater, comprising: obtaining a ceramic heater having a resistance heating element embedded along a planar pattern. 2. A ceramic heater comprising a ceramic base and a resistance heating element embedded inside the ceramic base along a predetermined planar pattern, wherein the resistance heating element is a linear body of a high melting point metal. Is a resistance heating element obtained by performing a heat treatment in a non-oxidizing atmosphere at a temperature equal to or lower than a primary recrystallization start temperature of the refractory metal while holding a wound body formed by winding the refractory metal along a predetermined planar pattern, Ceramic heater.