JP2831925B2 - Manufacturing method of 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.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor device such as an etching apparatus and a chemical vapor deposition apparatus, a so-called stainless steel heater or a heater of an indirect heating system has been generally used.
However, when these heat sources are used, particles may be generated by the action of the halogen-based corrosive gas,
Also, thermal efficiency was poor. To solve these problems,
The present inventors have proposed a ceramic heater in which a wire made of a high melting point metal is embedded in a dense ceramic base material. The wire is spirally wound inside the disc-shaped substrate, 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.

When manufacturing such a ceramic heater, a wire made of a high melting point metal is wound to obtain a wound body, and terminals are connected to both ends of the wound body. On the other hand, ceramic powder is charged into a press molding machine and preliminarily 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. The wound body is accommodated in this concave portion, and a ceramic powder is filled thereon, and this powder is uniaxially pressed to form a disc-shaped molded body, and the disc-shaped molded body is hot-pressed and sintered. A sintered body is manufactured.

On the other hand, at present, especially in a semiconductor process, the size of a semiconductor wafer tends to increase in order to increase the amount of semiconductor that can be processed at one time. Therefore,
When applied to such an application, it is necessary to increase the area of the ceramic heater. However, when the area of the ceramic heater becomes large, it becomes difficult to maintain the uniformity of the temperature distribution, and the possibility that the substrate is broken by thermal stress due to a heating cycle increases. For these reasons, it is generally difficult to increase the size of the disk-shaped ceramic heater.

Therefore, the present inventor studied installing a ring-shaped ceramic heater on the outer periphery of the disk-shaped ceramic heater. This is to make it possible to uniformly heat the entire semiconductor wafer having a large size.

[0006]

However, as described above,
It has been found that the following problem occurs when the annular ceramic heater and the disc-shaped ceramic heater are manufactured separately. That is, the following steps are required to manufacture an annular ceramic heater. As schematically shown in FIG. 8, the lower mold 4 of the press molding machine is used.
Is fitted with the formwork 1. On the lower mold 4, a predetermined amount of ceramic powder is filled along the inner surface 1 a of the mold 1. This ceramic powder is preformed until it has a certain degree of hardness. For example, a wire-shaped resistance heating element 3A is accommodated in the recess, and a ceramic powder is filled thereon, and the powder is uniaxially pressed to form a disk-shaped molded body 12. At this time, the resistance heating element 3A is embedded only on the outer peripheral side of the disc-shaped molded body 12, and the resistance heating element is not embedded on the inner peripheral side.

[0007] The disc-shaped compact is hot-press sintered to produce a disc-shaped fired body 17 as shown in FIG. A resistance heating element 3 </ b> A is buried inside the ceramic base 15 on the outer peripheral side. This ceramic substrate 1
7 is subjected to surface grinding, and then its side peripheral surface is ground so as to be circular. Next, the inner peripheral side of the ceramic base 15 is cut out by ultrasonic processing or the like, and as shown in FIG. 9B, a disc-shaped waste material 30 is cut out. As a result, a disk-shaped ceramic heater 6 having an annular shape in plan view is formed. At this time, the resistance heating element 3A is provided inside the annular ceramic base 8. A disc-shaped ceramic heater is provided in the inner peripheral surface 8a of the ceramic base 8.

However, according to such a manufacturing method, it is necessary to separately manufacture the annular heater 6 and the disk-shaped heater. That is, it is necessary to install the resistance heating element on the pre-formed body, form the formed body, fire the formed body, and perform the surface grinding and the circular processing. For this reason, the total time required for the production becomes longer, and the production equipment, especially the molding die and the hot press firing equipment are occupied for a long time,
Manufacturing costs increase.

Further, as shown in FIG. 9A, once the ceramic base 15 is manufactured, it is necessary to remove and discard the waste material 30 as shown in FIG. 9B. Therefore, the ceramic powder, which is the material of the waste material 30, is wasted, and the steps required for manufacturing the waste material 30, such as molding and hot press firing, are wasted.

[0010] Further, a mold as schematically shown in FIG.
It is also conceivable to manufacture an annular ceramic heater by using it as a mold for press molding or a mold for hot pressing. Here, the case where the mold of FIG. 10 is used for hot press sintering will be described. A lower mold 33 is installed in a mold frame 31, and the lower mold 33 has cylindrical projections 3.
3a are formed. The upper die 32 is provided with an annular projection 32a as viewed in plan. The annular shaped body 34 includes a resistance heating element 3A on the outer peripheral side. The molded body 34 is set around the projection 33a of the lower die 33, and the projection 32a is fitted and fixed to the projection 33a. Hot press sintering is performed in this state.

However, after firing, the outer peripheral surface of the sintered product of the compact 34 reacts with the inner peripheral surface 31a of the mold 31 and
The inner peripheral surface of the sintered product of the molded body 34 is
Reacts with the side peripheral surface 33b, thereby producing black scale. Therefore,
In order to remove an annular sintered product (ceramic heater) from this mold, it is necessary to break the hot press mold. In such a method, since an expensive hot press mold needs to be disposable and used, the cost is extremely high, which is impractical.

An object of the present invention is to shorten the total time required for manufacturing a ceramic heater, simplify the manufacturing process,
The purpose is to improve the utilization efficiency of the manufacturing equipment and reduce the manufacturing cost.

Further, an object of the present invention is to prevent the generation of waste materials as described above, thereby eliminating waste of materials of waste materials, and eliminating waste of equipment and energy required for production of waste materials. It is to be.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a ceramic heater in which a resistance heating element is embedded in a ceramic base, and includes a resistance heating element inside a molded body made of ceramic powder. The method comprises the steps of: embedding a plurality of molded articles; firing the molded article to produce a fired article; and dividing the fired article to produce a plurality of ceramic heaters.

[0015]

According to the present invention, a plurality of ceramic heaters are prepared by embedding a plurality of resistance heating elements inside a molded body, dividing the fired body after the firing step. That is, although one formed body is formed in the forming step and one fired body is formed in the firing step, as a result, a plurality of ceramic heaters can be manufactured.

Needless to say, conventionally, in order to manufacture a plurality of ceramic heaters, a plurality of formed bodies had to be manufactured in a forming step, and a plurality of fired bodies had to be manufactured also in a firing step. . Therefore, according to the present invention, the total time required for manufacturing the ceramic heater can be shortened, the manufacturing process can be simplified, the utilization efficiency of the manufacturing equipment can be improved, and the manufacturing cost can be reduced.

In a preferred embodiment of the present invention, the molded body has a disk shape, and the inner peripheral resistance heating element and the outer peripheral resistance heating element are embedded in the molded body. By dividing the fired body, a disc-shaped ceramic heater in which the inner peripheral resistance heating element is embedded and a planar annular ceramic heater in which the outer peripheral resistance heating element is embedded are manufactured.

Therefore, in addition to the above-described functions and effects, the above-described waste material 30 is not generated. As a result, it is possible to eliminate waste of the material of the waste material and waste of equipment, energy, and the like necessary for manufacturing the waste material.

In another embodiment of the present invention, a disc-shaped ceramic heater in which a resistance heating element is embedded is manufactured by dividing the fired body, wherein the molded article has a disc shape. .

In certain fields, it is necessary to manufacture a number of relatively small ceramic heaters, as opposed to semiconductor wafers. In such a case, if a plurality of ceramic heaters can be cut out from one disc-shaped fired body, the effect of simplifying the manufacturing process and improving the utilization efficiency of the manufacturing equipment is particularly large, and therefore, the manufacturing efficiency is greatly increased. Cost can be reduced.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Ceramics constituting a substrate include silicon nitride, aluminum nitride, sialon and the like.
According to the study of the present inventors, silicon nitride is particularly preferable from the viewpoint of thermal shock resistance, and aluminum nitride is preferable from the viewpoint of corrosion resistance to halogen-based corrosive gases and the like. Tungsten, as a high melting point metal constituting the resistance heating element,
Molybdenum, alloys thereof and the like are preferred.

An embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. As schematically shown in FIG.
The mold 1 is fitted to the lower mold 4 of the press molding machine. The ceramic powder is preformed until it has a certain degree of hardness. For example, wire-shaped resistance heating elements 3A, 3A
B is accommodated in the concave portion, and a ceramic powder is filled thereon, and the powder is subjected to uniaxial pressure molding to form a disk-shaped molded body 2. At this time, the resistance heating element 3A is embedded on the outer peripheral side of the disc-shaped molded body 2, and the resistance heating element 3B is embedded on the inner peripheral side.

The disk-shaped molded body 2 is hot-pressed and sintered.
As shown in FIG. 2A, a disc-shaped fired body 7A is manufactured. A resistance heating element 3A is embedded inside the ceramic substrate 5A on the outer peripheral side. A resistance heating element 3B is embedded inside the ceramic base 5A on the inner peripheral side. The ceramic base 7A is subjected to surface grinding, and then its side peripheral surface is ground so as to be circular.

Next, the inner peripheral side of the ceramic base 5A is hollowed out by ultrasonic processing or the like. As a result, as shown in FIGS. 2B and 3, a disc-shaped ceramic heater 6 having an annular shape in plan view can be manufactured, and
The disk-shaped ceramic heater 16 can be manufactured.

Inside the annular ceramic base 8,
A resistance heating element 3A is provided. Terminals 9A and 9B are connected to ends of the resistance heating element 3A, respectively. In the present embodiment, the resistance heating element 3A makes about two turns between the terminals 9A and 9B, but the number of turns is not particularly limited. A resistance heating element 3B is embedded inside the disc-shaped ceramic base 18. At the end of the resistance heating element 3B,
Terminals 9C and 9D are respectively connected.

A disc-shaped ceramic heater 16 is provided in the inner peripheral surface 8a of the ceramic base 8. Inner circumference 8
a and the side peripheral surface 18a of the base 18 are opposed to each other.

In the present embodiment, in addition to the above-described effects of the present invention, after the ceramic heater is manufactured,
Since no waste material remains, the cost of manufacturing waste material can be reduced.

As described with reference to FIGS. 1, 2 and 3,
Manufacturing experiments were actually performed on the above examples. However, the material of the resistance heating elements 3A and 3B is purity 99
%, A 0.5 mm diameter tungsten wire was used. The tungsten wire was spirally wound to obtain a wound body.
The diameter of the spiral shape of the wound body was 5 mm, and the pitch of the spiral was 0.5 mm.

The tungsten wire thus obtained was stretched so as to have a predetermined heat generation ratio, and terminals 9A, 9B, 9C and 9D were connected to both ends of the wound body, respectively. Figure 1
The wound body was installed and fixed on each of the annealing molds having the shape of each of the resistance heating elements 3A and 3B shown in FIG. 3, and in this state, heat treatment was performed at 1000 ° C. in a vacuum.

As the ceramic powder, silicon nitride powder after calcination was used. During uniaxial pressing,
Using a mold press, a pressure of 200 kg / cm ² was applied. The hot pressing process is performed at 1800 ° C in a nitrogen atmosphere.
It was carried out in.

After the disc-shaped fired body 7A thus obtained was subjected to cylindrical grinding and surface grinding, the disc-shaped fired body was subjected to X-ray photography to confirm the planar position of the tungsten wire. Then, it was processed by an ultrasonic processing machine having a frequency of 16 kHz and an output of 1000 watts, and divided to obtain ceramic heaters 6 and 16.

In this division, the heaters 6 and 16 are finally separated along the circular cutting line. First,
One main surface of the disc-shaped fired body 7A was turned upward, and a half was cut along the cutting line when viewed in the thickness direction. Then
The disc-shaped fired body 7A was repeatedly turned, the other main surface was turned upward, and the other half as viewed in the thickness direction was cut along the cutting line.

The terminals 9A, 9B, 9C and 9D were machined by electric discharge machining. Finally, the outer diameter of the disk-shaped ceramic heater 16 was 157 mm, and the thickness was 17 mm. The inner diameter of the annular ceramic heater 6 is set to 160
mm, the outer diameter was 235 mm, and the thickness was 17 mm. Here, it is preferable that the gap between the disc-shaped heater and the annular heater be t / d ≧ 8, where t is the thickness of the heater and d is the gap. If t / d is smaller than 8, that is, if the gap d is relatively large, a cold spot is likely to occur in the gap.

The ceramic heaters 6 and 16 prepared as described above were examined by an X-ray flaw detection test, an ultrasonic flaw detection test, and a zycro test. The appearance and the inside of the ceramic heater had no cracks, chips or damage. Did not.

Next, the insulation performance of each ceramic heater was examined using an apparatus schematically shown in FIG. However, in FIG. 4, the terminals 9A, 9B, 9C, and 9D are shown in one cross section for convenience of explanation. Also,
The ceramic heater 16 is formed with an insertion hole 4 for inserting a thermocouple for temperature measurement and control.
6 was formed.

First, the heaters 6 and 16 were allowed to stand in a stainless steel container 10. Next, water 11 was poured into the container 10 until the height of the surface of each terminal of each heater 6 and 16 was reached. At this time, water 11 was also injected into the insertion hole 4 and the screw hole 14 of the thermocouple. Then, using an insulation resistance measuring instrument (mega tester), the resistance 9A between the terminal 9A and the stainless steel container 10A, and the terminal 9C between the terminal 9C and the insertion hole 4 of the thermocouple B
And the resistance ΩC between the terminal 9C and the screw hole 14.
, A DC voltage of 500 V was applied and the resistance value was measured.

It was confirmed that each of these resistance values was 1000 MΩ or more. Terminal 9A─Stainless steel container 10
The resistance ΩA in the interval A is regarded as an insulation resistance value between the terminal and the ceramic substrate (other than the terminal installation surface). As a result, Ω
It was confirmed that the values of A, ΩB, and ΩC were respectively 2000 MΩ or more.

The ceramic heaters 6, 16 are
In vacuum, raise the temperature from room temperature to 1000 ° C,
The sample was kept at 1000 ° C. for 2 hours, and a heating test was performed. The temperature rising rate was 10 ° C./min. As a result, no problem occurred in the controllability and stability of the ceramic heater.

Next, an embodiment will be described in which the shape of the molded body is a disk shape and the fired body is divided to produce a disk-shaped ceramic heater in which a resistance heating element is embedded.

In this embodiment, a disk-shaped fired body 7B shown in FIG. 5 is manufactured. For this purpose, first, the ceramic powder is pre-molded to a certain degree of hardness. For example, four wire-shaped resistance heating elements 3C are accommodated in the recesses of the preform, and ceramic powder is filled thereon, and this powder is uniaxially pressed to form a disc-shaped molded body.

The disc-shaped compact is sintered by hot press to produce a disc-shaped fired body 7B as shown in FIG.
Four resistance heating elements 3C are embedded in the ceramic base 5B. Surface grinding of the ceramic base 5B,
Next, the side peripheral surface is ground so as to be circular.

Next, while inspecting the position of each resistance heating element 3C, the ceramic base 5B is hollowed out by ultrasonic processing or the like. As a result, as shown in FIGS. 6 and 7, a total of four disc-shaped ceramic heaters 26 can be manufactured.

Inside each disc-shaped ceramic substrate 28,
Each of the resistance heating elements 3C is provided. Terminals 9E and 9F are connected to the ends of the resistance heating element 3C, respectively. In the present embodiment, the resistance heating element 3C is connected to the terminal 9
Between E and 9F, there are about three rounds, but the number of rounds is not particularly limited.

As a result of cutting out four ceramic heaters 26 from the disc-shaped fired body 7B, 4
The circular holes 21 are left.

[0045]

As described above, according to the present invention, when manufacturing a plurality of ceramic heaters, the total time required for manufacturing the ceramic heater is shortened, the manufacturing process is simplified, and the utilization efficiency of the manufacturing equipment is reduced. And the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a molded body 2 molded in a mold of a press molding machine.

FIG. 2A is a sectional view showing a ceramic fired body 7A. (B) shows the ceramic heaters 6 and 16
FIG.

FIG. 3 is a plan view showing a state where the ceramic heater 16 is installed inside the ceramic heater 6;

FIG. 4 is a cross-sectional view showing a state where ceramic heaters 6 and 16 are installed in a container 10 for measuring an insulation resistance value.

FIG. 5 is a plan view showing a disc-shaped fired body 7B.

FIG. 6 shows a waste material 20 and a disc-shaped ceramic heater 2
FIG.

FIG. 7: Waste material 20 and disc-shaped ceramic heater 2
FIG.

FIG. 8 shows a molded body 12 molded in a mold of a press molding machine.
It is sectional drawing which shows typically.

FIG. 9A is a sectional view showing a disc-shaped fired body 17; (B) is a sectional view showing the annular ceramic heater 6 and the waste material 30.

FIG. 10 is a cross-sectional view schematically showing a hot press mold having a shape for manufacturing a ring-shaped ceramic heater.

[Explanation of symbols]

2, 12 molded body 3A outer peripheral resistance heating element 3B inner peripheral resistance heating element 3C resistance heating element 4 thermocouple insertion hole 5A 5B disc-shaped ceramic base 6 annular ceramic heater 7A disc-shaped ceramic fired body 8 Annular ceramic base 9A
9B 9C 9D 9E terminal 10 Stainless steel container 11 Water 16, 26 Disc-shaped ceramic heater 18, 28 Disc-shaped base 20, 30 Waste material

Continuation of the front page (56) References JP-A-63-216283 (JP, A) JP-A-2-86086 (JP, A) JP-A-4-324276 (JP, A) JP-A-4-101380 (JP) JP-A-4-98784 (JP, A) JP-A-5-94865 (JP, A) JP-A-3-126393 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB Name) H05B 3/20-3/38

Claims (3)

(57) [Claims] 1. A method of manufacturing a ceramic heater in which a resistance heating element is embedded in a ceramic substrate, comprising: embedding a plurality of resistance heating elements inside a molded body made of ceramic powder; A step of producing a fired body by firing the ceramic heater; and a step of forming a plurality of the ceramic heaters by dividing the fired body. 2. The molded body has a disk shape. An inner peripheral resistance heating element and an outer peripheral resistance heating element are buried inside the molded body, and the fired body is divided. 2. The ceramic heater according to claim 1, wherein a disk-shaped ceramic heater in which an inner peripheral resistance heating element is embedded and a planar annular ceramic heater in which the outer peripheral resistance heating element is embedded are manufactured. Method. 3. A disk-shaped ceramic heater in which the molded body has a disk-like shape and the fired body is divided to produce a disk-shaped ceramic heater in which each of the resistance heating elements is embedded.
A method for manufacturing the ceramic heater according to claim 1.