JP2533679B2 - Plate-shaped ceramic heater and method for manufacturing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plate-shaped ceramics heater that can be suitably used in a semiconductor manufacturing apparatus and the like, and a manufacturing method thereof.

(Prior art and its problems) The heating temperature at the time of high temperature processing required for semiconductor manufacturing is in the range of several hundred to 1000 ° C, and such high temperature processing steps include oxidation diffusion, thin film formation, annealing and gettering. , Sintering, etc.

In semiconductor manufacturing equipment requiring a super clean state, a corrosive gas such as a chlorine gas or a fluorine gas is used as a deposition gas, an etching gas, or a cleaning gas. Therefore, if a conventional heater in which the surface of the resistance heating element is coated with a metal such as stainless steel or Inconel is used as a heating device for heating the wafer in contact with these corrosive gases, these gases are used. Exposure to chlorides, oxides,
Unfavorable particles such as fluoride having a particle diameter of several μm are generated. Therefore, there are problems in impurity contamination and corrosion resistance.

Therefore, an infrared lamp is installed on the outside of the container that is exposed to deposition gas, etc., an infrared transmission window is installed on the outer wall of the container, and infrared rays are radiated to a heated object made of a material with good corrosion resistance such as graphite, to be heated An indirect heating type wafer heating device has been developed for heating a wafer placed on the upper surface of the wafer. However, this type has a larger heat loss than the direct heating type, it takes longer to raise the temperature, and the transmission of infrared rays is gradually hindered due to the deposition of the CVD film on the infrared ray transmission window. There is a problem that the window absorbs heat and the window is heated.

Further, a so-called high-frequency heating method is known, but it is difficult to control the temperature by this method and the wafer heating region cannot be soaked.

(Process leading to the invention) In order to solve the above problems, the present inventors newly embed a spiral resistance heating element in a disc-shaped dense ceramic, and hold this ceramic heater in a graphite case. The heating device was examined. As a result, this heating device was found to be an extremely excellent device that eliminated the above-mentioned problems.

However, it has been found that a new problem arises when this ceramic heater is used in an actual semiconductor device.

That is, since a spiral resistance heating element is embedded inside the ceramic molded body and fired by the hot pressing method, in order to prevent the resistance heating element from breaking during pressing, the resistance heating element,
It was necessary to give rigidity to the ceramic molded body. Therefore, it is necessary to increase the wire diameter of the linear resistance heating element and the thickness of the disk-shaped ceramic molded body to some extent, and it is not possible to reduce the thickness and form a fine heating element pattern.

For this reason, the resistance heating element is easily distorted during press molding, and the shape of the resistance heating element is different for each product, resulting in large variations in temperature distribution. Further, when the resistance heating element was embedded even in the outer peripheral portion of the ceramic molded body, cracks and breakage occurred in this molded body.

Furthermore, due to the above restrictions, it is not possible to reduce the thickness of the heater to reduce its heat capacity and increase the amount of heat generation, resulting in a slow response to changes in surface temperature and a slow heating rate. We could not increase the productivity of semiconductors.

(Problems to be Solved by the Invention) An object of the present invention is to prevent impurity contamination, to have excellent corrosion resistance and thermal shock resistance, and to overcome variations in temperature distribution among products, response speed, and slow temperature rising speed. It is to resist such a ceramic heater and its manufacturing method.

(Means for Solving the Problem) The present invention is formed by printing inside a disk-shaped silicon nitride sintered body and a silicon nitride sintered body, and is higher than the sintering temperature of the silicon nitride sintered body. It has a film-shaped resistance heating element made of a metal having a melting point, and contains Yb ₂ O ₃ and E in the silicon nitride sintered body.
_{r 2 O 3, Y 2 O} 3, Tm 2 O 3 and Lu ₂ O ₃ two or more rare earth oxides selected from the group consisting of are contained 50 mol of the total amount of rare earth oxide % To 95 mol% is occupied by one of the rare earth oxides, 50 mol% to 5 mol% is occupied by other rare earth oxides, and oxygen contained in the silicon nitride sintered body (from rare earth oxides Amount (excluding oxidation introduced)
The molar amount of the ratio of the rare earth oxide to the molar amount of SiO ₂ when converted into SiO ₂ is characterized in that it is a 0.4 to 1.3,
The present invention relates to a plate-shaped ceramics heater.

The present invention also provides a step of producing a disc-shaped silicon nitride compact; a resistance heating element paste containing metal powder having a melting point higher than the sintering temperature of the silicon nitride compact on the surface of the disc-shaped silicon nitride compact. A printing step of printing a disk-shaped silicon nitride molded body by covering at least the surface side of the disk-shaped silicon nitride molded body with a silicon nitride molding material; and sintering the silicon nitride heater molded body by a hot pressing method. A method for manufacturing a disk-shaped ceramics heater, comprising: Yb ₂ O ₃ , Er ₂ O ₃ , Y ₂ O ₃ , Tm ₂ O in a disk-shaped silicon nitride molded body and a silicon nitride molding material. ₃ and 2 or more rare earth oxides selected from the group consisting of Lu ₂ O ₃ is contained, and one kind of rare earth oxide occupies 50 mol% to 95 mol% of the total amount of rare earth oxides added. , 50 mol% to 5 mol% is occupied by other rare earth oxides And oxygen contained in the silicon nitride sintered body after sintering (excluding oxide introduced from the rare earth oxide)
When the amount of SiO ₂ is converted to SiO ₂ , the ratio of the molar amount of rare earth oxide to the molar amount of SiO ₂ is 0.4 to 1.3.

The resistance heating element paste may be printed in advance inside the “disk-shaped silicon nitride molded body”, and in this case, the resistance heating element is laminated after sintering.

(Example) First, a disk-shaped ceramics heater according to an example of the present invention will be described.

1 and 2 are partial cross-sectional views showing the silicon nitride ceramic heaters 1 and 11, respectively, and FIGS. 4 and 5 are cutaway plan views showing examples of resistance heating element patterns.

In this embodiment, a film-shaped resistance heating element 3 made of a metal having a melting point higher than the sintering temperature of the sintered body 2 is formed inside the disc-shaped silicon nitride sintered body 2 by printing. At this time, a plurality of layers (three layers in this example) of the resistance heating element 3 can be provided as shown in FIG. 1, and one layer can be provided as shown in FIG. A method of forming the resistance heating element 3 will be described later.

The resistance heating element 3 is formed in a pattern as shown in FIGS. 4 and 5, for example.

In the example shown in FIG. 4, the end portion 3a of the film-shaped resistance heating element is formed from the outer peripheral portion of the disk-shaped sintered body 2 toward the central portion, and the circular inner peripheral electrode 3b is provided. A central heating portion 3c is provided inside 3b, the end of the central heating portion 3c is connected to the connecting portion 3d, and a circular outer peripheral electrode 3e is formed from the heater outer peripheral side end of the connecting portion 3d to the entire heater outer peripheral edge portion. did. Then, a plurality of fan-shaped wiring patterns 3f as a whole are formed in a region between the inner peripheral electrode 3b and the outer peripheral electrode 3e, and this region is filled with a plurality of fan-shaped wiring patterns 3f (in order to make it easy to see in FIG. 4, , The pattern 3f is omitted in part.). As a result, mainly the inside of the inner peripheral electrode 3b is heated by the central heating portion 3c, and the space between the inner peripheral electrode 3b and the outer peripheral electrode 3e is heated by a plurality of fan-shaped wiring patterns 3f.

Also in the example of FIG. 5, a plurality of fan-shaped wiring patterns 3g are also formed between the inner peripheral electrode 3b and the outer peripheral electrode 3e to fill the space between the electrodes 3b and 3e (pattern 3g). Are partially omitted in the figure.).

FIG. 6 is a sectional view showing a state where the ceramics heater is attached to the thermal CVD device. Here, the resistance heating element 3 is not shown in the drawings for easy viewing.

In FIG. 6, 18 is a container used for semiconductor manufacturing CVD, 1 (or 11) is a disk-shaped ceramic heater for heating a wafer, which is attached to a case 7 inside thereof, and the size of the wafer heating surface 6 Is set to, for example, 4 to 8 inches, which is a size in which a wafer can be installed.

Gas for thermal CVD is supplied to the inside of the container 18 from the gas supply hole 16, and the air inside is exhausted from the suction hole 17 by a vacuum pump. Electric power is supplied from the outside through the electrode members 20 at the center and the end of the disk-shaped ceramic heater 1 (11), and the disk-shaped ceramic heater 1 (11) is, for example, 1100.
It can be heated to about ° C. 10 is a flange with a water cooling jacket 15 that covers the upper surface of the case 7, and is an O-ring.
The space between the side wall of the container 18 and 14 is sealed by 14 to form the ceiling surface of the container 18. Reference numeral 8 denotes a hollow sheath that is inserted into the inside of the container 18 by penetrating the wall surface of the flange 10 of the container 18 as described above, and is joined to the ceramic heater 1 (11). A thermocouple 9 with a stainless steel sheath is inserted inside the hollow sheath 8. Hollow sheath 8 and container 18
An O-ring is provided between the flange 10 and the flange 10 to prevent atmospheric air from entering.

It is preferable that the wafer heating surface 6 is a smooth surface. Especially when the wafer is directly set on the wafer heating surface 6, it is necessary to set the flatness to 500 μm or less to prevent the deposition gas from entering the back surface of the wafer. There is.

The disk-shaped ceramics heater of this embodiment can provide the following effects.

(1) Since the film-shaped resistance heating element 3 is formed inside the disk-shaped silicon nitride sintered body 2, it is possible to solve problems such as contamination of the inside of the apparatus and deterioration of thermal efficiency in the case of the indirect heating method.

(2) Since the silicon nitride sintered body is used as the heater base, it has high corrosion resistance against a corrosive gas and high thermal shock resistance, and cracks do not occur in the base even after repeated heating and cooling.

(3) Since the film-shaped resistance heating element is formed by printing, press molding is easy, and the film-shaped resistance heating element is less likely to be distorted during press molding. Therefore, the same pattern can be formed for each product without variation due to molding, and the difference in temperature distribution can be reduced. Further, since the pattern is formed by printing, it is possible to form a finer pattern as compared with the spiral heating element. Furthermore, even if a film-shaped resistance heating element is formed near the outer periphery of the disc-shaped sintered body 2, cracks are less likely to occur because the sintered body 2 is not unduly stressed.

Moreover, since the resistance heating element is in the form of a film, the molded body can be easily press-molded even if the heater wall thickness is reduced to reduce the heat capacity. Therefore, the response of the heater to changes in the surface temperature can be increased, and the heating rate of the heater can be increased.

In this sense, the thickness of the sintered body 2 is preferably 8 mm or less.

(4) In recent years, semiconductors are in the process of integration, and large-sized wafers are being used in the semiconductor manufacturing process. For example, in 16M DRAM, adoption of 8-inch type wafers is being considered. In order to form a fine pattern on such a semiconductor, it is important to uniformize the film formation and prevent the distortion of the wafer. In this respect, since the heater of this example is a resistance heating type,
Excellent heat uniformity.

(5) As shown in FIG. 1, when a plurality of film-shaped resistance heating elements 3 are provided, the heat generation amount per one layer can be suppressed to be small.

(6) When the metal forming the film-shaped resistance heating element 3 is tungsten or molybdenum, the adhesion between the resistance heating element 3 and the sintered body 2 is excellent.

(7) Conventionally, there is a ceramic heater in which a conductive ceramic paste is printed inside an insulating ceramic molded body and the molded body is sintered to form a conductive ceramic pattern. However, in such a heater, a phenomenon called a so-called heat spot occurs, which causes a breakage of the heating element.

In this respect, also in the present embodiment, even if the resistance heating element 3 made of a refractory metal is formed, as shown in FIG. 3, if there are small holes 4, for example, the cross-sectional area around the small holes 4 is small. The heat spot portion 5 is generated. Since the specific resistance of this portion is larger than that of the surroundings, the amount of heat generation increases and the temperature rises. This vicious cycle in which the specific resistance further increases due to this temperature rise leads to disconnection of the resistance heating element 3.

However, as shown in FIGS. 4 and 5, when a plurality of fan-shaped wiring patterns 3f or 3g are formed between the outer peripheral electrode 3e and the inner peripheral electrode 3b, the outer peripheral electrode 3e and the inner peripheral electrode 3b are separated from each other. Since they are connected in parallel, even if any one of the wiring patterns 3f or 3g is disconnected as described above, the other patterns are maintained as normal. Therefore, even if one of the wiring patterns 3f or 3g is broken, the uniform heat distribution can be maintained to some extent, so that the heater can be used. In this sense, the number of fan-shaped wiring patterns is preferably 30 or more.

In each of the above examples, the shape of the ceramic heater is
In order to uniformly heat the circular wafer, it is preferable to have a disk shape, but other shapes such as a square disk shape and a hexagonal disk shape may be used. Further, these ceramics heaters can also be applied to ceramics heaters in plasma etching devices, photo-etching devices and the like.

As a silicon nitride sintered body, the silicon nitride sintered body disclosed by the present applicant in Japanese Patent Application No. 62-29919 (Japanese Patent Laid-Open No. 63-10067) has high strength at high temperature and high thermal conductivity. Particularly preferred.

That is, this silicon nitride sintered body is Y ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂
It is a mixed powder of two or more kinds of rare earth oxides of O ₃ and Lu ₂ O ₃ and a silicon nitride raw material powder, and any one of the selected rare earth oxides has a total addition amount of rare earth oxides. with 95 mol% or less, selected total amount of rare earth oxide oxygen (excluding oxygen introduced from the rare earth oxide) of SiO ₂ in terms of SiO ₂ contained in the sintered body after sintering A mixed powder having a molar ratio of 0.4 to 1.3 is molded, the molded body is preferably calcined, and then the molded body is hot-press fired according to the present invention. In this silicon nitride sintered body,
Oxides of rare earth elements with small cation radius (Er ₂ O ₃ , Y
₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ ), preferably, Yb ₂ O ₃ is added in an amount of 50 to 9 based on the total amount of the rare earth oxide.
By mixing 5 mol%, more preferably Y ₂ O ₃ and Yb ₂ O ₃ , the densification of the silicon nitride sintered body is promoted. Even when a rare earth element having a large cation radius is used, it has a densification promoting effect, but its strength at high temperatures (1400 ° C) is not high. This is because the apatite structure containing a rare earth element having a large cation radius and the grain boundary phase having a small cation radius have different properties.

95% of the total amount of rare earth oxides added to any one of the rare earth oxides
Limiting to mol% or less is to lower the eutectic point, improve the wettability, in the liquid phase obtained by mixing two kinds outside this range.
This is because the densification effect of lowering the viscosity does not appear and a dense silicon nitride sintered body cannot be obtained. It should be noted that this addition amount includes at least Yb ₂ O ₃ , and Yb ₂ O ₃ is preferably 50 to 95 mol% of the total addition amount of the rare earth oxide, and Y ₂ O ₃ and Yb ₂ O ₃
Is more preferably Y ₂ O ₃ / Yb ₂ O ₃ = 50/50 to 5/95 in terms of molar ratio.

The total added molar amount of the rare earth oxides is the amount of oxygen contained in the sintered body after sintering (excluding oxygen introduced from the rare earth oxides)
The addition amount of the rare earth oxide is determined so that the ratio to the molar amount of SiO ₂ converted to O ₂ is 0.4 to 1.3, because the grain boundary liquid phase having a densification effect by adding in this ratio range is determined. Is obtained, and the grain boundary phase can be made substantially a crystalline phase having an apatite structure. If this ratio exceeds 1.3, a grain boundary liquid phase having a densification effect cannot be obtained and Ln ₄ Si ₂ O ₇ N
_A large amount of ₂ (Ln: rare earth element) is contained in the crystal phase. While the ratio is
If it is less than 0.4, a grain boundary liquid phase with a densification effect can be obtained, but Ln ₂ Si ₂ O ₇ (Ln: rare earth element) is included in the crystal phase, making it impossible to obtain a high-strength sintered body at high temperature. . In order to densify and become a high-strength and high-strength sintered body, at least the grain boundary phase of the silicon nitride particles substantially consists of a crystal phase, and at least 50% or more of the grain boundary phase needs to be a crystal phase having an apatite structure. It is desirable that substantially all are crystalline phases having an apatite structure. The molar ratio is more preferably 0.5 to 1.2.

An apatite crystal phase is a crystal phase of the same crystal structure as a hexagonal crystal having a chemical formula of Y ₁₀ (SiO ₄ ) ₆ N ₂ typified by JCPDS card 30-1462, and contains two or more rare earth elements. In the mixed-added sintered body of No. ₃ , the rare earth element ion is substituted at the position occupied by the Y ion of the crystal of Y ₁₀ (SiO ₄ ) ₆ N ₂ , and even if two or more kinds of rare earth elements are solid-dissolved. In addition, there is a case where O is substituted for the N position and the Y position becomes a hole in order to maintain electrical neutrality.

The amount of SiO ₂ is the amount of oxygen in the sintered body obtained by chemical analysis in consideration of the amount of oxygen contained in the silicon nitride raw material powder and the amount of oxygen introduced by the oxidation of silicon nitride during preparation. The amount of oxygen contained in the sintered body is subtracted by the additive, and the remaining amount of oxygen is converted to SiO ₂ . Therefore, when using a silicon nitride sintered body raw material powder with a small amount of oxygen, a silicon nitride raw material powder to which SiO ₂ has been added separately, or a powder in which the oxygen content has been increased by calcining the raw material powder, and due to a change in the preparation method, When the introduction amount is increased or decreased, the addition amount of the rare earth oxide is increased or decreased according to the SiO ₂ amount. The amount of SiO ₂ is preferably 1.0 to 5.0% by weight in order to obtain the amount of grain boundary phase for densification. If it is 1.0% by weight or less, the total amount of rare earth oxides is small and the amount of liquid phase for densification is insufficient, and if it is 5.0% by weight or more, the grain boundary phase becomes excessive and the high temperature strength is remarkably lowered and the silicon nitride content is low The original strength characteristics of the silicon nitride sintered body are lost.

Next, the procedure for manufacturing the disc-shaped ceramic heater of FIG. 1 will be described with reference to FIGS. 7 to 9.

First, a sintering aid is added to the silicon nitride raw material powder. At this time, it is preferable to further add a tungsten compound or a molybdenum compound, because it has the effect of blackening the sintered body.

From the viewpoint of sinterability, it is preferable that the silicon nitride raw material has a large α content. The oxygen content is preferably 1 to 3% by weight.

Next, these raw materials are mixed in distilled water with an attritor or the like. Thereafter, if necessary, iron removal and sieving are performed, and a granulating binder is added to the mixed powder to prepare a granulated powder. Next, this granulated powder is subjected to sizing, water content adjustment, sieving, and left as required.

After this, it is preferable to employ either of the following two types of steps.

(A) As shown in FIG. 7, a granulated powder, which is a silicon nitride molding material, is press-molded to produce a molded body 21, and the molded body 21 is preferably calcined at 400 to 800 ° C. to give strength. Then, a paste containing a metal having a melting point higher than the sintering temperature of the silicon nitride sintered body is printed on the surface 21a of the compact after calcination to form the resistance heating element paste layer 23. Then, this molded body
The upper surface of 21 is filled with granulated powder again and pressed to form,
The resistance heating element paste layer 23 is formed again on this molded body. Then, granulated powder is further filled on this and press-molded to obtain a disk-shaped silicon nitride compact 24 as shown in FIG. Then, the resistance heating element paste layer 23 is further printed on the surface 24a of the disk-shaped silicon nitride compact 24.

Then, the surface 24a of the disk-shaped silicon nitride molded body 24,
A disk-shaped silicon nitride heater molded body 25 shown in FIG. 9 is manufactured by covering with granulated powder which is a silicon nitride molding material and press-molding again.

Finally, this molded body 25 is preferably calcined at a temperature of preferably 400 to 800 ° C., and then hot pressed and sintered at a temperature of 1700 to 2100 ° C.

Organic substances are not fully decomposed at calcination temperatures below 400 ℃. On the other hand, at 800 ° C. or higher, the raw material silicon nitride is oxidized.

The reason for limiting the sintering temperature is that, at a temperature lower than 1700 ° C., the sinterability is not sufficient, high densification does not occur and strength is low. Meanwhile 2100
In the region exceeding ° C, silicon nitride is decomposed and pores increase inside the sintered body, resulting in insufficient densification.

(B) As shown in FIG. 7, the granulated powder is formed into a sheet to form a molded body 21, and the resistance heating element paste 23 is printed on the surface 21a of the molded body. Then, the resistance heating element paste 23 is laminated as shown in FIG. 9 by the method described above to produce a disk-shaped silicon nitride heater molded body 25, and the silicon nitride heater molded body 25 is processed as described above. Calcined to
Hot press sinter.

Further, in the example of FIGS. 7 to 9, three layers of resistance heating element paste layers 23 are formed, but in FIG. 7, the surface 21a of the disk-shaped silicon nitride compact 21 is covered with the granulated powder and press-formed. Then, a disk-shaped silicon nitride heater molded body can be manufactured by this, and the heater 11 shown in FIG. 2 can be manufactured by calcination and hot press sintering.

 Next, an experimental example will be described more specifically.

The heater of FIG. 1 was manufactured according to the method of (b) above. Here, the resistance heating element paste layer 23 was formed by screen printing, and the width of this layer was 500 μm and the thickness was 30 μm. The dimensions of the disk-shaped ceramics heater were 200 mm in diameter and 5 mm in thickness. The calcination temperature for scattering the binder is 450 ℃, and the pressure during hot press sintering is 200at.
m, and the sintering temperature was 1850 ° C.

 The composition of the resistance heating element paste was as follows.

The composition of the resistance heating paste used was a paste consisting of 70 weight percent tungsten powder and 5 weight percent Mo powder, 25 weight percent ethyl cellulose dissolved in butyl carbitol.

 The following silicon nitride was used.

1.32 wt% of Y ₂ O ₃ and 5.37 wt% of Yb ₂ O ₃ were added to 93.31 wt% of silicon nitride powder having a specific surface area of 15 m ² / g, an oxygen content of 1.5 wt% and an alpha conversion rate of 96%. This mixed powder was molded, calcined, and hot pressed and sintered.

The following experiments were conducted on the heater 1 thus obtained. As the pattern of the resistance heating element, that shown in FIG. 4 was adopted.

(Rate of temperature rise) 25 V was applied to the heater, and the time required for temperature rise from room temperature to each of the following temperatures was measured.

Room temperature → 400 ℃ 7 seconds Room temperature → 600 ℃ 12 seconds Room temperature → 800 ℃ 18 seconds Room temperature → 1000 ℃ 25 seconds (Temperature distribution) 600 ℃ to 1000 ℃ for the entire surface of 200mm diameter wafer
When the temperature distribution when heated to ℃ was measured by an infrared radiation thermometer, it was ± 1 ℃. Further, when heated to 400 ° C to 600 ° C, it was ± 1.4 ° C.

(Response to Pressure Fluctuation) First, the wafer heating surface is heated to 600 ° C., nitrogen gas is introduced into the container in FIG.
-Changed from ^-6 torr to 100 torr. Then, it took 1 second for the temperature of the wafer heating surface to recover to 600 ° C ± 3 ° C.
It took 4 seconds to recover to 00 ℃ ± 1 ℃.

Comparative example Nichrome wire resistance heating element embedded in coil shape, diameter 150m
Using a stainless steel heater having a thickness of 15 mm and a thickness of 15 mm, each test result described above was performed.

(Rate of temperature rise) 200 V was applied to the heater, and the time required for temperature rise from room temperature to each of the following temperatures was measured.

Room temperature → 400 ℃ 24 seconds Room temperature → 600 ℃ 39 seconds Room temperature → 800 ℃ 93 seconds Room temperature → 1000 ℃ No increase in temperature after 3 minutes.

(Temperature distribution) 400 ℃ ～ 600 on the entire surface of the wafer heated surface with a diameter of 150mm
When the temperature distribution when heated to ℃ was measured by an infrared radiation thermometer, it was ± 2.5 ℃. Further, it was ± 3 ° C when heated to 650 ° C to 700 ° C, and ± 4 ° C when heated to 750 to 800 ° C.

(Response to Pressure Fluctuation) First, the wafer heating surface is heated to 600 ° C., nitrogen gas is introduced into the container in FIG.
-Changed from ^-6 torr to 100 torr. It took 20 seconds for the temperature of the wafer heating surface to recover to 600 ° C. ± 3 ° C.

(Effect of the Invention) According to the plate-shaped ceramics heater and the method for manufacturing the same according to the present invention, since the resistance heating element is formed inside the plate-shaped silicon nitride sintered body, the device as in the case of the conventional stainless steel heater is used. There is no deterioration of thermal efficiency as in the case of indirect heating method or internal pollution of.

Moreover, since the silicon nitride sintered body is used as the heater substrate, it has high corrosion resistance and high thermal shock resistance.

Furthermore, since the film-shaped resistance heating element is formed by printing, it is easy to mold, it is less likely to be distorted during molding as compared with the spiral resistance heating element, and it is possible to form a finer pattern. Even if the resistance heating element paste is printed in the vicinity of the outer periphery of the disc-shaped sintered body, no undue stress is applied to this portion. Due to such ease of molding, it is possible to reduce the thickness of the sintered body and reduce its heat capacity, which speeds up the response of the heater to changes in the surface temperature,
In addition, the heating rate of the heater can be increased.

Moreover, since the heater substrate is made of a silicon nitride sintered body having a high temperature strength and the film-shaped resistance heating element is made of a metal having a melting point higher than the sintering temperature of the sintered body, a conventional stainless steel heater or the like is used. Can be used stably at higher temperatures.

Furthermore, two or more kinds selected from the group consisting of Yb ₂ O ₃ , Er ₂ O ₃ , Y ₂ O ₃ , Tm ₂ O ₃ and Lu ₂ O ₃ in the disk-shaped silicon nitride molded body and the silicon nitride molding material. Other rare earth oxides,
Of the total amount of rare earth oxides added, 50 mol% to 95 mol% is occupied by one kind of rare earth oxide, 50 mol% to 5 mol% is occupied by other rare earth oxides, and sintering of silicon nitride after sintering is performed. Compounded so that the ratio of the molar amount of rare earth oxide to the molar amount of SiO ₂ when converting the amount of oxygen (excluding oxidation introduced from rare earth oxide) contained in the body to SiO ₂ is 0.4 to 1.3. To do. As a result, the densification of the silicon nitride sintered body is promoted, and the heat from the film-shaped resistor easily conducts in the substrate,
The uniform heating property of the heating surface of the heater is improved, and the heat resistance of the entire heater is high, so that the heater can be used at high temperatures for a long time.

[Brief description of drawings]

1 and 2 are partial sectional views showing a disk-shaped ceramics heater according to an embodiment of the present invention, FIG. 3 is a sectional view for explaining a heat spot, and FIGS. 4 and 5 are films respectively. Plan view showing the formation pattern of the plate-shaped resistance heating element, FIG. 6 is a sectional view showing a state in which the disk-shaped ceramics heater is attached to the CVD device, and FIGS. 7, 8, and 9 are disk-shaped ceramics heaters. It is a sectional view for explaining a manufacturing process. 1,11 …… Disk-shaped ceramic heater 2 …… Disk-shaped silicon nitride sintered body 3 …… Membrane resistance heating element 3b …… Inner peripheral electrode, 3e …… Outer peripheral electrode 3f, 3g …… Overall fan shape Pattern 5 …… Heat pot part, 6 …… Wafer heating surface 18 …… Container 21 …… Molded body by sheet molding or press molding 23 …… Resistance heating element paste layer 24 …… Disk-shaped silicon nitride molded body 24a …… Surface of disk-shaped silicon nitride molded body 25 ... Disk-shaped silicon nitride heater molded body

Claims (2)

(57) [Claims] 1. A disk-shaped silicon nitride sintered body, and a film formed of a metal having a melting point higher than the sintering temperature of the silicon nitride sintered body formed by printing inside the silicon nitride sintered body. It has a resistance heating element.
_It contains two or more rare earth oxides selected from the group consisting of ₂ O ₃ , Er ₂ O ₃ , Y ₂ O ₃ , Tm ₂ O ₃ and Lu ₂ O ₃ , and the total amount of rare earth oxide added. 50% to 95% by mol of the rare earth oxides, 50% to 5% by mol.
Is occupied by other rare earth oxides, and the amount of oxygen (excluding oxidation introduced from the rare earth oxides) contained in the silicon nitride sintered body is converted into SiO ₂ , and the rare earths relative to the molar amount of SiO ₂ A plate-shaped ceramic heater characterized in that the molar ratio of oxides is 0.4 to 1.3. 2. A step of producing a disc-shaped silicon nitride compact; a resistance heating element containing, on the surface of the disc-shaped silicon nitride compact, a metal powder having a melting point higher than the sintering temperature of the silicon nitride compact. A printing step of printing a paste; a step of covering at least the surface side of the disk-shaped silicon nitride molded body with a silicon nitride molding material to produce a disk-shaped silicon nitride heater molded body; and hot pressing the silicon nitride heater molded body A method of manufacturing a disk-shaped ceramics heater, comprising: a sintering step of sintering by a method, wherein Yb ₂ O ₃ , Er ₂ O ₃ and Y _{2 are} contained in the disk-shaped silicon nitride molded body and the silicon nitride molding material. It contains two or more kinds of rare earth oxides selected from the group consisting of O ₃ , Tm ₂ O ₃ and Lu ₂ O ₃ , in which 50 mol% to 95 mol% of the total amount of the rare earth oxides are rare earth oxides. One kind of oxide occupies 50 mol% to 5 mol Percent accounted other rare earth oxides, and oxygen contained in the silicon nitride sintered body after sintering (excluding oxide introduced from the rare earth oxide) amount of SiO ₂ when converted into SiO ₂ of A method for producing a plate-shaped ceramic heater, characterized in that the mixture is made such that the molar ratio of the rare earth oxide to the molar amount is 0.4 to 1.3.