JP3495689B2 - 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 ceramic heater substrate used in a semiconductor product manufacturing apparatus or inspection apparatus, and more particularly to a hot plate (heater), a susceptor, an electrostatic chuck or a wafer used for drying semiconductor products. This is a proposal for a ceramic heater useful for a prober.

[0002]

2. Description of the Related Art An integrated circuit or the like provided in a semiconductor product is usually formed by applying a photosensitive resin as an etching resist on a silicon wafer and then etching the resin. In this case, since the photosensitive resin applied on the surface of the silicon wafer is applied by a spin coater or the like, it needs to be dried after the application. The drying process is carried out by placing a silicon wafer coated with a photosensitive resin on a hot plate and heating it. Conventionally, as such a hot plate, that is, a heater, one having a heating element wired on the back surface of a substrate made of a metal plate (aluminum plate) has been used.

[0003]

However, when a heater made of such a metal substrate is used for drying semiconductor products, there are the following problems. Since the substrate of the heater is made of metal, the thickness of the substrate must be 15 mm or more. This is because a thin metal substrate causes warping or distortion due to thermal expansion due to heating, and the wafer mounted on this substrate is damaged or tilted. Moreover, since the conventional heater is thick, it is heavy and bulky.

Further, when the heating temperature of the heater is controlled by changing the voltage and the amount of current applied to the heating element mounted on the substrate, when the thickness of the substrate is large, the temperature of the heater substrate fluctuates in the amount of voltage and current. There is also a problem in that the temperature control characteristics of the substrate are poor because the temperature does not follow quickly.

In order to solve such a problem, there is a conventional method disclosed in JP-A-9-
Japanese Patent No. 306642 and Japanese Patent Application Laid-Open No. 4-324286 propose a ceramic heater using an ALN substrate. However, in the conventional techniques disclosed in these publications, the heating element, the external terminal, and the
There is a problem that the external terminals and the heating element are insulated from each other due to the stress generated due to the difference in the coefficient of thermal expansion of each ceramic.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a ceramic heater which is excellent in temperature raising and lowering characteristics and adsorption ability and which is excellent in connection reliability between a conductor embedded in a substrate and an external terminal.

[0007]

[Means for Solving the Problems] For such problems,
As a means for overcoming this problem, the present invention proposes a ceramic substrate having the following essential configuration. That is, the present invention is to
Inside heating element ceramic substrate is embedded, the bag hole is provided from the substrate surface toward the buried heating element, and comprising to attach an external terminal through the blind bore ceramic
In the quartet , two or more recesses are formed on the inner wall of the bag hole.
Part is provided and the recess is filled with the conductive paste.
The conductive support is formed by and
At least a part of it is exposed on the inner wall surface of the bag hole
A conductive layer is formed on at least a part of the inner wall surface of the bag hole.
It is, and, wherein said heating element through the conductive layer and the external terminal is so as to be electrically connected
Ceramic heater .

In the ceramic heater according to the present invention, it is preferable that a conductive connection pad is provided in contact with the conductor and the bag hole is provided toward the connection pad portion. The external terminal is
It is preferable to electrically connect to a conductor or a conductive connection pad through a brazing material filled in the bag hole.

[0009]

Ceramic heater <br/> according to the present invention DETAILED DESCRIPTION OF THE INVENTION, ceramic-made plate-like member, i.e., the portion of the ceramic substrate, a nitride ceramic or a carbide ceramic insulation, and this substrate In, in the case of a heater, a plate-shaped conductor having a flat cross section, for example, a heating element, is embedded inside the ceramic substrate at a position eccentric from the thickness center in the substrate thickness direction, Moreover, the surface on the side farther from the heating element is the work surface, for example, the heating surface in the case of a heater.

Further, in the case where the present invention is used as a ceramic heater, as a means for electrically connecting a heating element embedded in the substrate and an external terminal, the substrate is directly connected or a connection pad (through hole). ) Through the blind hole
(Pin stand hole for terminal pin insertion) is formed, and by inserting the external terminal in this bag hole, it is possible to directly electrically connect with the heating element at the bottom of the hole or indirectly through the connection pad. It is a ceramic substrate that is designed to make various connections. In the present invention, in particular, by forming at least a part of the inner wall surface of the bag hole by a conductive layer, the electrical connection between the heating element and the external terminal can be achieved without using a conductive connection pad via the part of the conductive layer. The feature is that various connections are possible.

The role of the conductive layer formed on the inner wall surface of the bag hole is effective for ensuring reliable electrical connection between the heating element (or the conductive connection pad) and the external terminal.
In particular, even if the connection between the external terminal and the heating element (or connection pad) is destroyed for some reason, a reliable electrical connection is ensured through the conductive layer formed on the inner wall surface of the bag hole. To be able to do it. Therefore, in the present invention, at least three conductive layers are provided around the bag hole, and at least a part of these conductive layers is exposed on the inner wall surface of the pin hole and comes into contact with the inserted terminal pin. Is desirable. This can be said to be more desirable as the contact area between the external terminal and the conductive layer is increased.

Further, with regard to such a ceramic heater, since one end of the external terminal is inserted and supported in the bag hole, the external terminal (pin) does not rattle and the external terminal is connected. Since it is connected to the heating element through the pad and through the cylindrical bag hole formed in this connection pad, even if a force is applied to the external terminal, stress will be applied to the connection pad and bag hole. You can evenly distribute the force without concentration. Therefore, it is possible to prevent cracks from being generated in the embedded heating element and the ceramic substrate itself, and to effectively prevent the external terminals from falling off.

When the heating element is provided in a plurality of layers in the thickness direction of the substrate, the conductive connection pad is provided with a through hole for connecting the heating elements extending vertically or a heating element and an electrostatic chuck. You may make it function as a through hole for connecting between.

In such a ceramic heater, the substrate is
A ceramic plate-like body, that is, a ceramic substrate is made of an insulating nitride ceramic or carbide ceramic,
And, in this ceramic substrate, the aspect ratio is 1
A structure in which a flat plate-shaped heating element of 0 to 5000 is embedded is used. This ceramic substrate is
It preferably has a thickness of about 5 to 5 mm. This is because if it is too thin, it will break easily.

In the present invention, the reason why an insulating nitride ceramic, a carbide ceramic or an oxide ceramic is used as the ceramic substrate is that these ceramics have a smaller thermal expansion coefficient than metal, and even if they are thin, they warp due to heating. It is not distorted. as a result,
The present invention allows the substrate to be thin and light.
In addition, such a ceramic substrate has high thermal conductivity,
In addition, since the substrate itself is thin, the surface temperature of the ceramic substrate has a characteristic that it easily responds quickly to the temperature change of the heating element. That is, when the voltage and the current amount of the heating element embedded in the ceramic substrate are changed, the changes immediately appear as a temperature change of the substrate heating surface, so that it can be said that the temperature control characteristic and the temperature raising / lowering characteristic are excellent.

As the nitride ceramic, it is desirable to use at least one selected from metal nitride ceramics such as aluminum nitride, silicon nitride, boron nitride and titanium nitride. Further, as the carbide ceramic, it is desirable to use at least one selected from metal carbide ceramics, for example, silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide. As the oxide ceramic, it is desirable to use one or more selected from magnesia, alumina, beryllia, zirconia, cordierite, mullite and titania. Of these ceramics, aluminum nitride is the most preferred. This is because the highest thermal conductivity is 180 W / m · K.

Next, in the ceramic heater, a plate-shaped heating element having a flat cross section is embedded inside the substrate, and the embedded position is embedded at a position eccentric from the center of the substrate in the thickness direction. The surface farther from the heating element is the working surface (heating surface). With a ceramic heater that employs such a configuration, heat propagation is likely to spread uniformly throughout the ceramic substrate, and for example, the pattern of the heating element is projected as it is on the heating surface, resulting in an uneven temperature distribution. There is nothing to do. That is, the temperature distribution on the heating surface can be made uniform.

As described above, the shape of the heating element has a cross-sectional aspect ratio (width of heating element / thickness of heating element) of 10 to 10.
A flat shape having a range of 5000 is desirable. The one having such a shape is characterized in that the temperature distribution on the heating surface can be made more uniform than the one having a perfect circular cross section or a shape having a cross section close to a square. That is, if the cross-sectional aspect ratio of the heating element is less than 10, wasteful heat transfer in the lateral direction (side surface direction of the ceramic substrate) becomes larger than heat transfer from the heating element in the upward direction (wafer heating surface direction). In addition, the temperature distribution is similar to that of the wiring shape of the heating element. On the other hand, when the aspect ratio exceeds 5000, heat is accumulated in the vicinity of the center of the heating element, and an uneven temperature distribution also occurs, so that it becomes impossible to secure the uniformity of the plate surface temperature.

A more preferable aspect ratio is 100 to 30.
00. That is, when the aspect ratio is less than 100, the heating element is likely to become a starting point of cracks, while when it exceeds 3000, the sintering between the green sheets is obstructed at the time of production to form an interface between the green sheets, which becomes the starting point. This is because cracks occur. In the case of a heating element having such an aspect ratio, the impact resistance temperature ΔT of the ceramic substrate is
(Temperature at which cracks and peeling occur when dropped in water) is 150
It works effectively even at temperatures above ℃.

In the case of such a ceramic heater,
The heating element is embedded in a position deviated from the thickness center of the substrate in the thickness direction thereof, and the surface far from the heating element is configured as a working surface (heating surface). The reason for configuring in this way is that heat propagation easily diffuses throughout the heater plate, and is effective in preventing a temperature distribution similar to the pattern of the heating element from occurring on the heating surface. This is because the temperature distribution can be made uniform. That is, it is desirable that the position be embedded at a position which is deviated from the one surface (heating surface) of the substrate by more than 50% to 99%. If it is less than 50%, it is too close to the heating surface and a temperature distribution similar to the pattern of the heating element 2 occurs. On the other hand, if it exceeds 99%, the substrate 1 itself warps and the wafer is damaged. Because.

Specifically, as shown in FIGS. 1 and 2, the heating element 2 preferably has a concentric wiring pattern, for example, in order to make the temperature of the entire ceramic substrate 1 uniform. In the aspect ratio, it is preferable that the plate has a flat plate shape of 1 to 50 μm and a width of 0.3 to 20 mm. Within the above range, it is possible to increase the relative thickness of the heating element for the purpose of preventing disconnection or the like. The reason for limiting the thickness and width in this way is that this range is most practical in controlling the resistance value. Another reason for limiting the structure (thickness, width) of the heating element 2 as described above corresponds to the need to increase the width of the heating element itself. That is, when the heating element 2 is embedded inside the substrate 1, the temperature uniformity of the surface is deteriorated when the distance between the heating surface 1a and the heating element 2 is shortened, so that widening is effective.

When the heating element 2 is provided inside the substrate, it is not necessary to consider the adhesion to the substrate material such as a nitride ceramic, so that a refractory metal such as W or Mo, or W or Mo. Carbides can also be used, and thus the resistance value can be increased. The resistance value increases as the heating element 2 becomes thinner and thinner.

The heating element 2 may have a rectangular cross section, an ellipse, a spindle, or a kamaboko shape as long as it is a flat plate. The reason why the flat plate-shaped body is adopted is that when the heating element is provided inside, the flat shape is more likely to dissipate heat toward the heating surface, so that uneven temperature distribution on the heating surface is less likely to occur. It should be noted that even if the heating element has a flat cross section, a spiral coil shape has the same heat transfer effect as that of the circular cross section, and thus is not included in the present invention.

The heating element 2 may be arranged in a plurality of layers in the thickness direction of the substrate 1. In this case, it is preferable that the patterns of the respective layers are buried in positions complementary to each other when viewed in a plane, so that somewhere on the heating surface must be covered by the pattern of one of the layers. To be buried. For example, the structures are arranged in a zigzag pattern. The heating element 2 may be partly exposed on the surface as long as it is embedded inside the substrate 1.

In the present invention, as a method of embedding the heating element in a predetermined position of the substrate 1, coating on one of the green sheets for laminating a conductive paste containing metal particles,
It can be formed by printing. The conductive paste generally contains a resin, a solvent, a thickener, etc. in addition to metal particles or conductive ceramics for ensuring conductivity. The metal particles are preferably at least one selected from tungsten and molybdenum. This is because these metals are relatively hard to oxidize and have a resistance value sufficient to generate heat. Further, as the conductive ceramic, at least one selected from carbides of W and Mo
More than one species can be used.

The particle size of these metal particles or conductive ceramics is preferably 0.1 to 100 μm.
This is because if it is too fine, it is easily oxidized, and if it is too large, it becomes difficult to sinter and the resistance value increases.

As the resin used for the conductive paste,
Epoxy resin and phenol resin are preferable. Further, isopropyl alcohol or the like is used as the solvent.
Examples of the thickener include cellulose and the like.

In the present invention, since the heating element is formed inside the ceramic substrate, the surface of the heating element is not oxidized. Therefore, it is not necessary to coat the surface of the heating element with an antioxidant or the like.

In the present invention, the heating element 2 is embedded inside the ceramic substrate 1. In this case, in order to connect to the external terminal, the ceramic substrate 1 is connected as described above.
Basically, a pinhole 5 is drilled from the surface of the heating element 2 toward the heating element 2. In addition to that, a connection pad 4 is provided in contact with the heating element 2 and the external terminal 3 is connected via the connection pad 4. You may make it connect. That is, the connection pad 4 can be formed by filling a tungsten paste into a through hole (via hole) opened from the surface opposite to the heating surface of the substrate 1 toward the heating element 2. . The diameter of the connection pad 4 is 0.1 to
The size is preferably 10 mm. That is, if the size of the connection pad 4 is about this size, it is effective in preventing cracks and distortions while preventing disconnection. The connection between the connection pad 4 and the external terminal pin 3 is
This is performed by filling the opening (pin hole) 5 provided in the connection pad 4 with a brazing material and inserting the brazing material together with the pin 3 at the same time. Au-Ni alloy is desirable as the brazing material. This is because the Au-Ni alloy has excellent adhesion to tungsten. The ratio of this Au / Ni alloy is 81.5-
82.5Au / 18.5 to 17.5Ni is preferable. Also, this A
The thickness of the u-Ni alloy layer is 0.1 to secure the connection.
It is desirable to set the thickness to about 50 μm.

In the present invention, the thermocouple 6 can be embedded in the ceramic substrate 1 if necessary. This is because the temperature of the ceramic substrate 1 can be measured with a thermocouple and the temperature of the substrate can be controlled by changing the voltage and current amount based on the data.

In the usage pattern of the ceramic heater of the present invention, as shown in FIG. 2, a plurality of through holes 7 are provided in the ceramic substrate 1, the support pins 8 are inserted into the through holes 7, and the substrate is provided on top of the pins 8. The semiconductor wafer 9 is heated and dried while facing the heating surface of No. 1 and supporting the semiconductor wafer 9. In this usage mode, the support pins 8 can be moved up and down to pass the semiconductor wafer 9 to a carrier (not shown), or the semiconductor wafer 9 can be received from the carrier.

Next, a method for manufacturing the ceramic heater will be described. (1) A step of mixing a ceramic powder such as a nitride ceramic or a carbide ceramic with a binder and a solvent to obtain a green sheet (green molded body): In the processing of this step, such a ceramic powder is aluminum nitride,
Silicon carbide or the like can be used, and if necessary, a sintering aid such as yttria may be added. As the binder, at least one selected from acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinylal
More than one kind is desirable. Further, the solvent is preferably at least one selected from α-terpione and glycol. The paste obtained by mixing these is molded into a sheet by the doctor blade method to produce a green sheet. A through hole 7 for inserting the support pin 8 for the silicon wafer and a recess 11 for embedding a thermocouple can be opened in the green sheet. The through holes 7 and the recesses 11 can be formed by applying a punching method or the like. The thickness of the green sheet is 0.1
About 5 mm is good.

(2) Step of printing a conductive paste which becomes a heating element on the green sheet: In the processing of this step, a conductive paste such as a metal paste or a conductive ceramic is applied to the heating element forming portion on the green sheet. Apply or print. These conductive pastes contain metal particles or conductive ceramic particles. Tungsten or molybdenum is the most suitable as such metal particles, and tungsten or molybdenum carbide is most suitable as the conductive ceramic particles. This is because it is difficult to oxidize and the thermal conductivity does not easily decrease. The average particle diameter of tungsten particles or molybdenum particles is 0.1 to 5
μm is good. This is because it is difficult to print the paste when it is too large or too small. As such a paste, 85 to 97 parts by weight of metal particles or conductive ceramic particles,
1.5 to 10 parts by weight of at least one binder selected from acrylic, ethyl cellulose, butyl cellosolve and polyvinylal, and 1.5 to 1 of at least one solvent selected from α-terpione and glycol.
The most suitable is a tungsten paste or a molybdenum paste prepared by mixing 0 parts by weight.

(3) At least a conductive paste printed green sheet for the heating element 2 obtained in the step (2) and a green sheet not printed with the paste obtained in the same step as the step (1), respectively. Step of laminating one or more sheets: In this step, when two or more layers of green sheets are laminated, each of the green sheets laminated on the upper side (meaning heating surface side) of the green sheet with paste in (2) It is important that the number of green sheets to be laminated on the lower side is smaller than the number of green sheets (1) so that the embedded position of the heating element 2 is eccentric in the thickness direction. Specifically, 20 to 50 sheets are laminated on the upper side and 5 to 20 sheets are laminated on the lower side.

(4) Step of forming a bag hole and a conductive support member in the green sheet laminated material obtained as described above: This step is performed from the surface of the ceramic substrate 1 on the non-heated side to The blind hole 5 is formed by making a hole toward the heating element 2. The bag hole 5 may also be formed by making a hole in the connection pad 4 portion provided adjacent to the heating element 2. At least a part of the inner wall surface of the bag hole 4 is made of a conductor connected to the heating element 2.
For example, as shown in FIG.
The conductive support members 12 as shown in are provided at equal intervals. Then, these conductive supporting members 12 are exposed on the inner wall surface of the bag hole 4, and the external terminal connecting pin 3 inserted into the bag hole 5 is formed.
The electrically conductive support member 12 is used for electrical connection with.

(5) A step of heating and pressing the green sheet laminate to sinter the green sheet and the conductive paste to form a ceramic substrate, a heating element and a connection pad: In this step, the heating temperature is from 1000 to 20
The pressure is 100 to 200 kg / cm ² and the temperature is 00 ° C., and the pressurization is performed in an inert gas atmosphere. Argon, nitrogen, etc. can be used as the inert gas.

(6) Finally, the blind hole 5 provided directly in contact with the heating element 2 or the blind hole 5 provided in the connection pad 4 part.
After printing a solder paste as a brazing material, the external terminal connecting pin 3 is inserted and then heated to reflow the paste. The heating temperature is preferably 200 to 500 ° C. Further, the thermocouple 6 can be embedded in the recess 11 if necessary. In the ceramic heater described above, an electrostatic chuck electrode (not shown) may be embedded between the wafer heating surface and the heating element.

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

Examples Example 1 (ceramic heater) (1) Aluminum nitride powder (manufactured by Tokuyama, average particle size 1.1)
μm) 100 parts by weight, yttria (yttrium oxide, average particle size 0.4 μm) 4 parts by weight, acrylic binder
A composition obtained by mixing 11.5 parts by weight, 0.5 parts by weight of a dispersant and 53 parts by weight of an alcohol composed of 1-butanol and ethanol was used to obtain a green sheet having a thickness of 0.47 mm by a doctor blade. (2) After drying the green sheet at 80 ° C. for 5 hours,
The following conductive paste A was printed on the green sheet forming the heating element 2 by drawing a pattern using a screen printing method. The printing pattern was concentric circles as shown in FIG. (3) Centering on the green sheet on which the tungsten paste forming the heating element 2 is printed, the upper side (heating side)
37 sheets of green sheet on which the conductive paste A for forming the heating element 2 is not printed on the upper side (heating side) and 13 sheets on the lower side opposite to the green sheet, and at 130 ° C and a pressure of 80 kg / cm ² . Laminated. Conductive paste A: 100 parts by weight of tungsten carbide particles having an average particle size of 1 μm, acrylic binder 3.0
Parts by weight, 3.5 parts by weight of α-terpione solvent, dispersant 0.
3 parts by weight were mixed to prepare a conductive paste A. Conductive paste B: 100 parts by weight of tungsten particles having an average particle size of 3 μm, 1.9 parts by weight of an acrylic binder, α
A conductive paste B was prepared by mixing 3.7 parts by weight of a terpione solvent and 0.2 part by weight of a dispersant. (4) 600 ° C of the green sheet laminate in nitrogen gas
Degreasing was performed for 5 hours, and hot pressing was performed at 1890 ° C. and a pressure of 150 kg / cm ² for 3 hours to obtain an aluminum nitride plate-shaped body having a thickness of 3 mm. This is cut into a circle with a diameter of 230 mm and the thickness is 6
A ceramic plate-shaped body having a heating element of μm and a width of 10 mm was formed (FIG. 3 (a)). (5) After polishing the plate-like body obtained in (4) with a diamond grindstone, a hole is punched with the diamond grindstone to form a recess 11 for the thermocouple 6.
With punching, punching diameter 1.8 mm, 3.0 mm,
A through hole 7 (FIG. 2) for inserting a 5.0 mm semiconductor wafer support pin 8 and a blind hole 5 for connecting the heating element 2 and the external terminal connecting pin 3 were provided. (Fig. 3 (b)). (6) Further, a part of the inner wall surface of the bag hole 5 is cut out to form three recesses as shown in FIG. 4, and the conductive paste B is printed and filled to form a conductive support member. 12 is formed, and a brazing material made of a Ni-Au alloy is used for the bag hole 5,
Reflowing was carried out by heating at 0 ° C to fix the external terminal connecting pin 3 made of Kovar (Fig. 3 (c)). The terminal pins 3 are connected by the conductive support member 12 in order to secure the connection reliability. (7) A plurality of thermocouples 6 for suppressing temperature were embedded in the recess to obtain a heater 100 (Fig. 3 (d)).

Example 2 (Silicon Carbide Ceramic Plate Heater) Basically the same as Example 1, except that 100 parts by weight of silicon carbide powder having an average particle size of 1.0 μm, 11.5 parts by weight of an acrylic binder, and 0.5 of a dispersant. A composition obtained by mixing 53 parts by weight of alcohol and 1 part of butanol and ethanol was mixed with a doctor blade to obtain a green sheet having a thickness of 0.50 mm. A ceramic heater was formed by setting the sintering temperature to 1900 ° C.

Comparative Example 1 Basically the same as in Example 1, but the inner wall of the bag hole was not filled with tungsten paste. Regarding the heaters corresponding to the examples and the comparative examples thereof, which are suitable for the present invention, the temperature ranges from room temperature to 6
After conducting the temperature raising / lowering test at 00 ° C. 1000 times, the presence or absence of electrical insulation of the four terminal pins was examined. The results are shown in Table 1.
Although there is no insulated part in the example,
In the comparative example, one part was insulated.

[0048]

[Table 1]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

As described above, the ceramic of the present invention is
According to Kuhita, excellent in lifting temperature characteristic property, it is possible to improve the connection reliability of buried the conductor and the external terminals.

[Brief description of drawings]

FIG. 1 is a schematic view showing a pattern of a heating element.

FIG. 2 is a partial cross-sectional view showing a usage state of a ceramic heater.

FIG. 3 is a schematic diagram showing a manufacturing process of a ceramic heater.

FIG. 4 is a perspective view showing a connection structure portion of a terminal.

[Explanation of symbols]

1 Ceramic substrate 2 heating element 3 External terminal connection pin 4 connection pads 5 bag holes 6 thermocouple 7 through holes 8 Wafer support pins 9 wafers 11 recess 12 Conductive support member

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H05B 3/20 328 H05B 3/20 328 // H01L 21/027 H01L 21/30 567 (56) Reference JP-A-8-306629 (JP, A) JP 11-12053 (JP, A) JP 9-213455 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/68 H01L 21 / 66 H05B 3/02 H05B 3/20 328 H01L 21/027

Claims (4)

(57) [Claims] " 1. A ceramic heater in which a heating element is embedded inside a ceramic substrate, a bag hole is provided from the surface of the substrate toward the embedded heating element, and an external terminal is attached through the bag hole. The inner peripheral wall of the bag hole is provided with two or more recesses, and the recesses are filled with a conductive paste to form a conductive support portion, and at least a part of the conductive support portion is formed in the bag hole. By being exposed to the inner wall surface of the bag hole, a conductive layer is formed on at least a part of the inner wall surface of the bag hole, and the heating element and the external terminal are electrically connected through the conductive layer. A ceramic heater characterized by: 2. A ceramic heater in which a heating element is embedded inside a ceramic substrate, a bag hole is provided from the substrate surface toward the embedded heating element, and an external terminal is attached through the bag hole. , Two or more recesses are provided in the inner peripheral wall of the bag hole, and the conductive support is provided by filling the recesses with a conductive paste,
By exposing at least a part of the conductive support portion to the inner wall surface of the bag hole, a conductive layer is formed on at least a part of the inner wall surface of the bag hole, and the heating element and the outside are connected via the conductive layer. A ceramic heater characterized by being electrically connected to a terminal. 3. The ceramic heater according to claim 1, wherein a conductive connection pad is provided in contact with the heating element, and the bag hole is provided toward the connection pad portion. 4. The ceramic heater according to claim 1, wherein the external terminal is electrically connected to a heating element or a conductive connection pad via a brazing material filled in the bag hole.