JP2002334820A - Ceramic heater for heating semiconductor wafer or liquid crystal substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater which is used for heating a semiconductor wafer or a liquid crystal substrate and capable of heating a target, such as semiconductor wafer or liquid crystal substrate more uniformly than normally, because a part of the semiconductor wafer or the like adjacent to a through-hole bored in the ceramic heater is hardly decreased in temperature, when an object of heating, such as the semiconductor wafer or the liquid crystal substrate, is placed on it and is heated. SOLUTION: A heating body is provided on the surface of a disk-like of a disk-like ceramic board or inside the board, and a through-hole in which a lifter pin is inserted is bored in the ceramic board for the formation of a ceramic heater used for heating a semiconductor wafer or a liquid crystal substrate. The above through-hole has a tapered shape, whose one opening located on the one surface of the ceramic heater brought into contact with the semiconductor wafer or the like, is larger in diameter than its other opening located on the other surface of the ceramic heater opposed to the former.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater used for drying, sputtering, etc., mainly in the semiconductor industry, and more particularly, to a ceramic heater for manufacturing or inspecting semiconductor or liquid crystal substrates.

[0002]

2. Description of the Related Art Conventionally, heaters using a metal substrate such as stainless steel or an aluminum alloy have been used in semiconductor manufacturing and inspection apparatuses including an etching apparatus and a chemical vapor deposition apparatus. However, the metal heater has a problem that the temperature control characteristic is poor, and the thickness is large, so that the heater is heavy and bulky, and the corrosion resistance to corrosive gas is also poor.

On the other hand, Japanese Patent Application Laid-Open No. 11-40330 discloses a heater using a ceramic such as aluminum nitride instead of a metal heater.

Usually, ceramic heaters of this type include:
As shown in FIG. 7, a resistance heating element 42 is formed inside a ceramic substrate 41, and a through hole 45 for inserting a lifter pin is formed. By inserting the lifter pins into the through holes 45 and moving the lifters up and down, the semiconductor wafers and the like are relatively easily received from the previous process,
Further, a semiconductor wafer or the like can be transferred to a subsequent process. Reference numeral 44 denotes a bottomed hole 44 for embedding a temperature measuring element such as a thermocouple, and 43 denotes a resistance heating element 42.
Is an external terminal for connecting to a power supply.

[0005]

However, when an object to be heated such as a semiconductor wafer or a liquid crystal substrate is heated using the ceramic heater 40 having such a through-hole 45, the vicinity of the through-hole 45 is locally localized. A so-called cooling spot, which is low in temperature, causes a problem in that the temperature of the semiconductor wafer, the liquid crystal substrate, etc. decreases in this area, making it difficult to uniformly heat the semiconductor wafer, the liquid crystal substrate, etc. There has occurred.

The present invention has been made in view of such a conventional problem. Even if a through hole for a lifter pin is formed, a cooling spot does not occur in a through hole portion of a heating surface, and a semiconductor is formed. An object of the present invention is to provide a ceramic heater that can uniformly heat an object to be heated such as a wafer or a liquid crystal substrate.

[0007]

In order to solve the above problems, a ceramic heater for heating a semiconductor wafer or a liquid crystal substrate according to the present invention comprises a heating element formed on the surface or inside of a disk-shaped ceramic substrate. A ceramic heater for heating a semiconductor wafer or a liquid crystal substrate provided with a through hole for inserting a lifter pin into a substrate,
The diameter of the through-hole on the heating surface side for heating the object to be heated,
The diameter is larger than the diameter on the opposite side (hereinafter, referred to as the bottom side) of the heating surface.

In a ceramic heater for heating a semiconductor wafer or a liquid crystal substrate provided with a through hole for inserting a lifter pin, the side wall of the through hole is usually in contact with a gas having a lower temperature than the substrate portion. The temperature decreases around the side wall of the hole, and a cooling spot is generated on the heated surface.

When a semiconductor wafer, a liquid crystal substrate, or the like is placed on the semiconductor wafer or the ceramic heater for heating the liquid crystal substrate, heat is taken away by the cooling spot at the cooling spot, so that the temperature of that portion decreases, and The temperature uniformity of the wafer, the liquid crystal substrate, and the like is lost.

However, according to the ceramic heater for heating a semiconductor wafer or a liquid crystal substrate of the present invention, the diameter of the through-hole on the heating surface side is larger than the diameter of the surface on the opposite side of the heating surface. In the portion where the spot is generated, the solid constituting the substrate does not exist, and the space occupies a large proportion and the heat capacity decreases. Therefore, the temperature of the semiconductor wafer, the liquid crystal substrate and the like near the through hole is hardly reduced, and the heating object such as the semiconductor wafer and the liquid crystal substrate can be more uniformly heated.

Further, when forming a through-hole having a diameter on the heating surface side larger than a diameter on the bottom surface side, the through-hole is formed of a columnar portion and an enlarged-diameter portion which increases in diameter as approaching the heating surface. In other words, if it is configured to have a funnel shape, the stored gas stays in the funnel-shaped portion, and the cooling spot itself does not expand, so that the heated object such as a semiconductor wafer, a liquid crystal substrate, etc. can be further uniformized. Can be heated. In addition, the through hole having the above shape can be formed relatively easily by using a drill or the like, so that the through hole can be efficiently formed. The enlarged portion heats the wafer and the like while keeping the space. This is because when the filling member is filled in the enlarged diameter portion, the ceramic and the filling member slide to generate particles.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A ceramic heater for heating a semiconductor wafer or a liquid crystal substrate according to the present invention has a heating element formed on the surface or inside of a disk-shaped ceramic substrate, and for inserting a lifter pin through the ceramic substrate. A ceramic heater for heating a semiconductor wafer or a liquid crystal substrate provided with a through-hole, wherein the diameter of the through-hole on the heating surface side for heating an object to be heated is larger than the diameter on the bottom surface side. I do. In the following description, the ceramic heater for heating a semiconductor wafer or a liquid crystal substrate will be simply referred to as a ceramic heater. In the present invention, the diameter of the through hole on the heating surface side is preferably 1.2 to 10 times the diameter on the opposite side of the heating surface. This is because if the diameter on the heating surface side is less than 1.2 times the diameter on the opposite side of the heating surface or more than 10 times, the heat storage effect cannot be obtained.

FIG. 1 is a plan view schematically showing a ceramic heater of the present invention, and FIG. 2 is a partially enlarged cross-sectional view schematically showing the ceramic heater of FIG. In this ceramic heater, a heating element is formed inside a ceramic substrate.

In this ceramic heater 10, the ceramic substrate 11 is formed in a disk shape, and the heating surface 11 a of the ceramic heater 10 is heated so that the entire temperature thereof is uniform. A heating element 12 having a concentric pattern is formed.

Immediately below the end of the heating element 12, a through hole 13a is formed.
Is formed in the bottom surface 11b, and the external terminal 13 is inserted into the blind hole 13b and joined with a brazing material or the like (not shown). Further, a socket (not shown) having a conductive wire is attached to the external terminal 13, for example, and the conductive wire is connected to a power supply or the like.

A bottomed hole 14 for inserting a temperature measuring element (not shown) is formed in the bottom surface of the ceramic substrate 11.

Further, a through hole 15 for inserting a lifter pin 16 is provided near the center of the ceramic substrate 11.
Individually formed. As shown in FIG. 2, the through hole 15 includes a columnar portion 15a and an enlarged diameter portion 15b that increases in diameter as approaching the heating surface. The through hole 15 has a funnel shape as a whole, and a cooling spot is generated. In the easy part, the solid constituting the substrate hardly exists, and instead, a gas such as air exists.

Accordingly, the heat capacity of the portion where the cooling spot is apt to be generated is reduced, and due to the presence of this portion, the portion of the semiconductor wafer 39 where the temperature is lowered is less likely to be generated. Since gas such as air accumulates heat and stays in the portion where
Can be uniformly heated. In FIG. 2, the through-hole 15 approaches the heating surface from the vicinity of the heating surface, specifically, a position where the ratio of the distance from the heating surface of the ceramic substrate to the thickness of the ceramic substrate is 2/3 or less. Has a shape that is suddenly expanding,
A through-hole having a shape that gradually increases in diameter from the vicinity of the bottom surface side may be used in order to make it easier for gas such as stored air to stay in the vicinity of the heating surface.

When heating the semiconductor wafer 39 using the ceramic heater 10, the semiconductor wafer 39 is received using the lifter pins 16, and then the semiconductor wafer 39 is placed on a heating surface, and the ceramic heater is energized. By heating the lifter pins 16 in a state where the lifter pins 16 slightly protrude from the heating surface 11 a of the ceramic substrate 11, the lifter pins 16 are held at a certain distance from the heating surface 11 a of the ceramic substrate via the lifter pins 16. The semiconductor wafer 39 may be supported and the semiconductor wafer 39 may be heated.

In particular, when a semiconductor wafer or the like is placed so as to be in contact with a heating surface, it is usually susceptible to a cooling spot near the through-hole.
As described above, since the diameter of the through-hole on the heating surface side is large and a cooling spot is not easily generated, the semiconductor wafer and the like can be more uniformly heated than before.

Before and after the step of performing a heat treatment or the like using the ceramic heater of the present invention, this through hole 1
After the lifter pin 16 is inserted through the
By moving the semiconductor wafer up and down, the semiconductor wafer and the like can be relatively easily received from the previous process, and the semiconductor wafer and the like can be transferred to the subsequent process.

When a semiconductor wafer or the like is supported on the lifter pins 16, the semiconductor wafer or the like and the ceramic substrate do not slide, so that no particles are generated from the ceramic substrate.

Further, by arranging a pin or the like having a projection structure on the surface of the ceramic substrate, the lifter pins are held slightly protruding from the heating surface of the ceramic substrate in the same manner as the semiconductor wafer. It is possible to heat a semiconductor wafer or the like in a state in which the heating surface of the ceramic substrate and the like are separated from each other.

In the ceramic heater of the present invention, the heating element may be formed inside the ceramic substrate, or may be formed outside the ceramic substrate.

FIG. 3 is a bottom view schematically showing another example of the ceramic heater of the present invention. FIG. 4 is a partially enlarged sectional view schematically showing the ceramic heater of FIG. In this ceramic heater, a heating element is formed on the surface of the ceramic substrate.

In the ceramic heater 20, the ceramic substrate 21 is formed in a disk shape, and a heating element 22 having a concentric pattern is formed on the surface of the ceramic substrate 21.
Are formed, and external terminals 23 serving as input / output terminals are connected to both ends thereof via a metal coating layer 220. Further, a bottomed hole 24 for inserting a temperature measuring element (not shown) is formed on the bottom surface of the ceramic substrate 21.

Further, a through hole 25 for inserting the lifter pin 16 is provided near the center of the ceramic substrate 21.
The through holes 25 are formed in the same manner as in the case of the ceramic heater 10 and have a cylindrical portion 25a and an enlarged diameter portion 25b.
The solid which forms the substrate hardly exists in the portion where the cooling spot is easily generated. Therefore, the heat capacity of a portion where a cooling spot is easily generated can be greatly reduced, and the semiconductor wafer 39 can be heated more uniformly.

Further, by inserting the lifter pins 16 through the through holes 25 and moving them up and down, a semiconductor wafer or the like can be carried, and the lifter pins 16 are made to protrude from the heating surface 21 a of the ceramic substrate 21. Thus, the semiconductor wafer 39 can be held apart from the ceramic substrate 21a.

In the ceramic heater of the present invention, the shape of the through-hole is not particularly limited as long as the diameter on the heating surface side is larger than the diameter on the bottom surface side. As shown in FIG. 2, it is preferable to be constituted by a columnar portion and an enlarged diameter portion.

The number of through holes formed in the ceramic substrate is preferably three or more. When there are two or less through holes,
This is because it becomes difficult to stably support an object to be heated such as a semiconductor wafer by the lifter pin inserted into the through hole. The number of through-holes is not particularly limited as long as it is three or more, but even in the case of the present invention, there is no substitute for the fact that a cooling spot is easily generated in the through-hole portion. The number is preferably not too large,
For example, it is desirable that the number is 11 or less.

Although the position of the through hole is not particularly limited, the through hole is formed in a region where the distance from the center to the outer edge of the ceramic substrate is 1/2 or more from the center. It is desirable. More stable,
This is because a semiconductor wafer or the like can be supported. Also, since the volume of the outer peripheral part is larger than that of the central part,
When a through hole is formed near the center, the heat capacity of the central portion is reduced by forming the through hole, and the temperature is likely to be high at the central portion. And the temperature of the heating surface can be made uniform.

In addition, since the semiconductor wafer and the like can be more stably supported and the semiconductor wafer and the like can be more uniformly heated, the above-mentioned through-hole is formed in one circle concentric with the ceramic substrate. It is desirable to be formed at substantially equal intervals on the circumference.

When four or more through holes are formed in the ceramic substrate, one through hole may be provided at the center of the ceramic substrate. With the lifter pins, the semiconductor wafer or the like can be held apart from the ceramic substrate, and when heated, the bending of the central portion of the semiconductor wafer or the like can be prevented,
As a result, the distance between the semiconductor wafer or the like and the ceramic substrate becomes constant, and the semiconductor wafer or the like can be uniformly heated.

When the semiconductor wafer or the like is separated and held by the lifter pins and heated, the height at which the lifter pins inserted into the through holes project from the heating surface of the ceramic substrate is 5 to 5000 μm. That is, the semiconductor wafer or the like is placed 5 to 5000 μm from the heating surface of the ceramic substrate.
It is desirable to keep them apart. If it is less than 5 μm, the temperature of the semiconductor wafer or the like becomes uneven due to the influence of the temperature distribution of the ceramic substrate, and if it exceeds 5000 μm, the temperature of the semiconductor wafer or the like hardly rises.
This is because the temperature of the outer peripheral portion of the semiconductor wafer or the like becomes low. The heated object and the heating surface of the ceramic substrate
It is more preferable that the distance is 500 μm.
It is even more desirable to be spaced apart by μm.

The diameter of the through hole is preferably 1 to 100 mm, more preferably 1 to 20 mm. When the diameter of the through hole is a trapezoidal shape in cross section, the diameter of the through hole refers to the diameter of the bottom and the center of the heating surface. When it consists of a part, it shall mean the diameter of the columnar part.

If the diameter of the through-hole is less than 1 mm, the lifter pins inserted into the through-hole become too thin, so that it becomes difficult to stably mount a semiconductor wafer or the like on the lifter pins. When the diameter exceeds 100 mm, the through hole is too large, so that a cooling spot is easily generated on the heating surface under the influence of gas present inside the through hole, and the portion where the through hole exists and the through hole do not exist. Since the heat capacity at a certain area of the ceramic substrate differs between the portions, the temperature of the heating surface tends to be non-uniform, and the semiconductor wafer or the like may not be heated uniformly.

In the ceramic heater of the present invention, the diameter of the ceramic substrate is desirably 200 mm or more. This is because the larger the diameter of a ceramic heater, the larger the diameter of a semiconductor wafer or the like in which bending is likely to occur, so that the configuration of the present invention functions effectively. . The diameter of the ceramic substrate is especially 12 inches (300 mm)
It is desirable that this is the case. This is because it will become the mainstream of next-generation semiconductor wafers and the like.

The thickness of the ceramic substrate is 25 mm
It is desirable that: This is because if the thickness of the ceramic substrate exceeds 25 mm, the temperature followability decreases. Further, its thickness is desirably 0.5 mm or more. When the thickness is smaller than 0.5 mm, the strength of the ceramic substrate itself is reduced, so that the ceramic substrate is easily broken. More preferably, it is more than 1.5 and 5 mm or less. When the thickness is more than 5 mm, the heat is difficult to propagate, and the heating efficiency tends to decrease. On the other hand, when the thickness is less than 1.5 mm, the heat propagating in the ceramic substrate is not sufficiently diffused, so that the temperature variation on the heating surface is caused. May occur, and the strength of the ceramic substrate may be reduced to cause breakage.

In the ceramic heater according to the present invention, a bottomed hole is provided on the ceramic substrate from the side opposite to the heating surface on which the object to be heated is placed, toward the heating surface, and the bottom of the bottomed hole is moved from the heating element. It is also desirable to form the heating element relatively close to the heating surface and to provide a temperature measuring element (not shown) such as a thermocouple in the bottomed hole.

The distance between the bottom of the bottomed hole and the heating surface is:
It is desirable that the thickness be 0.1 mm to 1/2 of the thickness of the ceramic substrate. Thereby, the temperature measurement location is closer to the heating surface than the heating element, and more accurate measurement of the temperature of the semiconductor wafer or the like becomes possible.

The distance between the bottom of the bottomed hole and the heating surface is 0.1 mm
If the thickness is less than the above, heat is dissipated, and a temperature distribution is formed on the heating surface. If the thickness exceeds 1/2, the temperature is easily affected by the temperature of the heating element, and the temperature cannot be controlled. This is because it is formed.

The diameter of the bottomed hole is desirably 0.3 mm to 5 mm. This is because if it is too large, the heat dissipation will be large, and if it is too small, the workability will be reduced and the distance to the heating surface cannot be equalized.

It is preferable that a plurality of the bottomed holes are arranged symmetrically with respect to the center of the ceramic substrate and form a cross. This is because the temperature of the entire heating surface can be measured.

As the temperature measuring element, for example, a thermocouple,
Platinum resistance thermometers, thermistors and the like can be mentioned. As the thermocouple, for example, JIS-C-1602 (1
980), K type, R type, B type, S type
Type, E-type, J-type, and T-type thermocouples, and among them, a K-type thermocouple is preferable.

It is desirable that the size of the junction of the thermocouple is the same as or larger than the diameter of the strand, and is 0.5 mm or less. This is because, if the junction is large, the heat capacity increases and the responsiveness decreases. It is difficult to make the diameter smaller than the diameter of the strand.

The temperature measuring element may be adhered to the bottom of the bottomed hole using gold brazing, silver brazing, or the like, or may be inserted into the bottomed hole and sealed with a heat-resistant resin. , May be used in combination. Examples of the heat-resistant resin include a thermosetting resin, particularly an epoxy resin, a polyimide resin, a bismaleimide-triazine resin, and the like. These resins may be used alone or in combination of two or more.

As the above-mentioned gold brazing material, 37-80.5% by weight Au-63-19.5% by weight Cu alloy, 81.5-8%
2.5% by weight: Au-18.5 to 17.5% by weight: Ni
At least one selected from alloys is desirable. These are because the melting temperature is 900 ° C. or higher and it is difficult to melt even in a high temperature region. As a silver solder, for example, Ag
-A Cu-based material can be used.

The material of the ceramic substrate constituting the ceramic heater of the present invention is not particularly limited. For example, a nitride ceramic or a carbide ceramic is preferable. Nitride ceramics and carbide ceramics have a smaller coefficient of thermal expansion than metals and have much higher mechanical strength than metals, so even if the thickness of the ceramic substrate is reduced,
Does not warp or warp due to heating. Therefore, the ceramic substrate can be made thin and light. Further, since the thermal conductivity of the ceramic substrate is high and the ceramic substrate itself is thin, the surface temperature of the ceramic substrate quickly follows the temperature change of the heating element. That is, the surface temperature of the ceramic substrate can be controlled by changing the voltage and the current value to change the temperature of the heating element.

As the nitride ceramic, for example,
Examples include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. These may be used alone or 2
More than one species may be used in combination.

Examples of the carbide ceramic include silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide. These may be used alone or in combination of two or more.

Of these, aluminum nitride is most preferred. The highest thermal conductivity is 180W / m · K,
This is because it has excellent temperature followability.

When a nitride ceramic, a carbide ceramic, or the like is used as the ceramic substrate, an insulating layer may be formed if necessary. Nitride ceramics have a tendency to decrease in volume resistance at high temperatures due to oxygen solid solution, etc.Carbide ceramics have conductivity unless particularly highly purified. This is because, even if it contains, a short circuit between circuits can be prevented and the temperature controllability can be ensured.

The insulating layer is preferably made of an oxide ceramic, specifically, silica, alumina, mullite,
Cordierite, beryllia and the like can be used.
Such an insulating layer may be formed by spin-coating a sol solution obtained by hydrolyzing and polymerizing an alkoxide on a ceramic substrate, followed by drying and firing, or by sputtering, CVD, or the like. Further, an oxide layer may be provided by oxidizing the surface of the ceramic substrate.

The thickness of the insulating layer is desirably 0.1 to 1000 μm. If the thickness is less than 0.1 μm, the insulating property cannot be secured, and if the thickness exceeds 1000 μm, the thermal conductivity from the heating element to the ceramic substrate is impaired. Further, it is desirable that the volume resistivity of the insulating layer is 10 times or more (same measurement temperature) as the volume resistivity of the ceramic substrate. If it is less than 10 times, a short circuit cannot be prevented.

Further, the ceramic substrate of the present invention contains carbon, and its content is desirably 200 to 5000 ppm. This is because the electrode can be concealed and black body radiation can be easily used.

The ceramic substrate has a brightness of JI.
It is desirable that the value based on the definition of SZ8721 be N6 or less. This is because a material having such a lightness is excellent in radiant heat and concealing property. Where the lightness N
Sets the ideal black lightness to 0 and the ideal white lightness to 1
Each color is divided into 10 so that the perception of the brightness of the color becomes equal between the brightness of black and the brightness of white, and the symbols are indicated by symbols N0 to N10. The actual measurement is performed by comparing the color charts corresponding to N0 to N10. In this case, the first decimal place is 0 or 5.

When the heating element is provided, it may be formed on the surface (bottom surface) of the ceramic substrate or may be embedded inside the ceramic substrate. When the heating element is formed inside the ceramic substrate, the heating element is desirably formed at a position of 60% or less in the thickness direction from the surface opposite to the heating surface. If it exceeds 60%, the heat propagating in the ceramic substrate is not sufficiently diffused because it is too close to the heating surface,
This is because temperature variations occur on the heating surface.

When the heating element is formed inside the ceramic substrate, a plurality of heating element forming layers may be provided. In this case, it is desirable that the heating elements are formed in some layers so that the patterns of the respective layers complement each other, and when viewed from above the heating surface, the patterns are formed in any regions.
As such a structure, for example, a structure in which the staggered arrangement is provided. The heating element may be provided inside the ceramic substrate, and the heating element may be partially exposed.

When a heating element is provided on the surface of the ceramic substrate, the heating surface is desirably opposite to the heating element forming surface. This is because the ceramic substrate plays a role of thermal diffusion, so that the temperature uniformity of the heating surface can be improved.

When the heating element is formed on the surface of the ceramic substrate, a conductor paste containing metal particles is applied to the surface of the ceramic substrate to form a conductor paste layer having a predetermined pattern, which is then baked. A method of sintering metal particles on the surface is preferred. The sintering of the metal is sufficient if the metal particles and the metal particles and the ceramic are fused.

When a heating element is formed inside a ceramic substrate, its thickness is preferably 1 to 50 μm. When a heating element is formed on the surface of the ceramic substrate, the thickness of the heating element is preferably 1 to 30 μm,
-10 μm is more preferred.

When a heating element is formed inside the ceramic substrate, the width of the heating element is preferably 5 to 20 μm. When a heating element is formed on the surface of the ceramic substrate, the width of the heating element is preferably 0.1 to 20 mm,
0.1-5 mm is more preferable.

The resistance of the heating element can be varied depending on its width and thickness, but the above range is most practical. The resistance value increases as the resistance value decreases and the resistance value decreases. When the heating element is formed inside the ceramic substrate, both the thickness and the width are larger.However, when the heating element is provided inside, the distance between the heating surface and the heating element becomes shorter, and the uniformity of the surface temperature is improved. It is necessary to increase the width of the heating element itself, and it is not necessary to consider the adhesion to nitride ceramics etc. to provide the heating element inside, so high melting point of tungsten, molybdenum, etc. Metals, carbides such as tungsten and molybdenum can be used, and the resistance value can be increased. Therefore, the thickness itself may be increased for the purpose of preventing disconnection and the like. Therefore, it is desirable that the heating element has the above-described thickness and width.

By setting the formation position of the heating element in this way, while the heat generated from the heating element propagates, it diffuses throughout the ceramic substrate and heats the object to be heated (such as a semiconductor wafer). Is uniformed, and as a result, the temperature in each part of the object to be heated is equalized.

The pattern of the heating element in the ceramic heater of the present invention is not limited to the concentric pattern shown in FIG. 1, but may be, for example, a spiral pattern, an eccentric pattern, or a repetitive pattern of bent lines. Etc. can also be used. These may be used in combination. In addition, by making the heating element pattern formed on the outermost periphery into a pattern divided in the circumferential direction, it is possible to perform fine temperature control on the outermost periphery of the ceramic heater, whose temperature tends to decrease, It is possible to suppress temperature variations. Furthermore, the pattern of the heating element divided in the circumferential direction may be formed not only on the outermost periphery of the ceramic substrate but also on the inside thereof.

The heating element may have a rectangular or elliptical cross section, but is preferably flat. This is because the flat surface is more likely to dissipate heat toward the heating surface, so that the temperature distribution on the heating surface is less likely to occur. The aspect ratio of the cross section (the width of the heating element / the thickness of the heating element) is preferably 10 to 5000. By adjusting to this range, the resistance value of the heating element can be increased, and the uniformity of the temperature of the heating surface can be ensured.

When the thickness of the heating element is constant, if the aspect ratio is smaller than the above range, the amount of heat propagation in the direction of the heating surface of the ceramic substrate becomes small, and the heat distribution approximated to the pattern of the heating element is reduced. On the other hand, if the aspect ratio is too large, the temperature directly above the center of the heating element becomes high, and eventually, a heat distribution approximate to the pattern of the heating element is generated on the heating surface. Therefore, in consideration of the temperature distribution, the aspect ratio of the cross section is preferably 10 to 5000.

When the heating element is formed on the surface of the ceramic substrate, the aspect ratio is 10 to 200. When the heating element is formed inside the ceramic substrate, the aspect ratio is 20.
It is desirable to set it to 0 to 5000.

The aspect ratio becomes larger when the heating element is formed inside the ceramic substrate.
This is because, when the heating element is provided inside, the distance between the heating surface and the heating element is shortened, and the temperature uniformity of the surface is reduced. Therefore, it is necessary to flatten the heating element.

The conductive paste used for forming the heating element is not particularly limited, but may contain metal particles or conductive ceramic for securing conductivity, and may further include a resin, a solvent, and a thickener. And the like are preferred.

As the metal particles, for example, noble metals (gold, silver, platinum, palladium), lead, tungsten, molybdenum, nickel and the like are preferable, and among them, noble metals (gold, silver, platinum, palladium) are more preferable. Also,
These may be used alone, but it is desirable to use two or more kinds in combination. This is because these metals are relatively hard to oxidize and have a resistance value sufficient to generate heat. Examples of the conductive ceramic include carbides of tungsten and molybdenum. These may be used alone or in combination of two or more.

The metal particles or conductive ceramic particles preferably have a particle size of 0.1 to 100 μm. 0.1μ
If the particle size is too small, it is easily oxidized.
If the thickness exceeds μm, sintering becomes difficult and the resistance value increases.

Even if the shape of the metal particles is spherical,
It may be scaly. When these metal particles are used, they may be a mixture of the above-mentioned spheres and the above-mentioned flakes. When the metal particles are scaly, or a mixture of spherical and scaly, it is easy to hold the metal oxide between the metal particles, and the adhesion between the heating element and the nitride ceramic is improved. This is advantageous because it can be ensured and the resistance value can be increased.

As the resin used for the conductor paste,
For example, an epoxy resin, a phenol resin, and the like can be given. Examples of the solvent include isopropyl alcohol. Examples of the thickener include cellulose and the like.

As described above, it is preferable that the metal paste is added to the metal particles in the conductor paste, and the heating element is formed by sintering the metal particles and the metal oxide. By sintering the metal oxide together with the metal particles in this manner, the ceramic particles, ie, the nitride ceramic or the carbide ceramic, can be adhered to the metal particles.

It is not clear why the mixing of the metal oxide with the nitride ceramic or the carbide ceramic improves the adhesion, but the surface of the metal particles and the surface of the nitride ceramic and the carbide ceramic are slightly oxidized. It is considered that an oxide film is formed by sintering and integrating the oxide films via the metal oxide, and the metal particles adhere to the nitride ceramic or the carbide ceramic.

As the metal oxide, for example,
Lead, zinc oxide, silica, boron oxide (B _Two O_Three ), Al
Selected from the group consisting of Mina, Yttria and Titania
At least one is preferred.

This is because these oxides can improve the adhesion between the metal particles and the nitride ceramic or the carbide ceramic without increasing the resistance value of the heating element.

The ratio of the above-mentioned lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is as follows: 1-10, silica 1-30, boron oxide 5-50, zinc oxide 20-70, alumina 1
-10, yttria 1-50, titania 1-50, and the total is preferably adjusted within a range not exceeding 100 parts by weight. By adjusting the amounts of these oxides in these ranges, the adhesion to the nitride ceramic can be particularly improved. The amount of the metal oxide added to the metal particles is preferably 0.1% by weight or more and less than 10% by weight.

Further, a metal foil or a metal wire can be used as the heating element. As the metal foil, nickel foil,
It is desirable to use a stainless steel foil as a heating element by forming a pattern by etching or the like. The patterned metal foil may be bonded with a resin film or the like. Examples of the metal wire include a tungsten wire and a molybdenum wire.

The area resistivity when the heating element is formed is preferably 1 mΩ / □ to 10 Ω / □. When the sheet resistivity is less than 1 mΩ / □, the resistivity is too small and the amount of heat generated is small, so that it becomes difficult to function as a heating element. On the other hand, when the sheet resistivity exceeds 10 Ω / □, the applied voltage On the other hand, the calorific value is too large, and it is difficult to control the calorific value of the ceramic substrate provided with the heating element on the surface of the ceramic substrate. From the viewpoint of controlling the amount of generated heat, the area resistivity of the heating element is more preferably 1 to 50 mΩ / □. However, when the area resistivity is increased, the pattern width (cross-sectional area) can be increased, and the problem of disconnection is less likely to occur. Therefore, in some cases, it is preferable to set the resistance to 50 mΩ / □.

When the heating element is formed on the surface of the ceramic substrate 21, it is desirable that a metal coating layer (see FIG. 4) 220 be formed on the surface of the heating element. This is to prevent the internal metal sintered body from being oxidized to change the resistance value. The thickness of the metal coating layer 220 to be formed is
0.1 to 10 μm is preferred.

The metal used for forming the metal coating layer 220 is not particularly limited as long as it is a non-oxidizing metal. Specifically, for example, gold, silver, palladium, platinum,
Nickel and the like can be mentioned. These may be used alone or in combination of two or more. Among these,
Nickel is preferred.

The heating element 12 requires a terminal for connection to a power supply, and this terminal is connected to the heating element 12 via solder.
This is because nickel prevents thermal diffusion of the solder. Examples of the connection terminal include an external terminal 13 made of Kovar.

When the heating element is formed inside the ceramic substrate, the surface of the heating element is not oxidized, and thus no coating is required. When the heating element is formed inside the ceramic substrate 11, a part of the heating element may be exposed on the surface, and a through hole for connecting the heating element is provided in the terminal portion, and the terminal is connected to the through hole. , May be fixed.

When connecting the connection terminals, as the solder,
Alloys such as silver-lead, lead-tin, and bismuth-tin can be used. The thickness of the solder layer is 0.1 to 50.
μm is preferred. This is because the range is sufficient to secure connection by soldering. In addition, the ceramic heater of the present invention can be used in a temperature range of 100 to 800 ° C.

Next, a method for manufacturing the ceramic heater of the present invention will be described. First, a ceramic heater having a heating element 12 formed inside a ceramic substrate 11 (see FIGS. 1 and 2)
5) will be described with reference to FIG.

(1) Step of Producing Ceramic Substrate First, a ceramic powder such as a nitride ceramic is mixed with a binder, a solvent and the like to prepare a paste, and a green sheet 50 is produced using the paste.

As the above ceramic powder such as nitride, aluminum nitride or the like can be used. If necessary, a sintering aid such as yttria, a compound containing Na or Ca, or the like may be added. The binder is preferably at least one selected from an acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol.

Further, as the solvent, at least one selected from α-terpineol and glycol is desirable. A paste obtained by mixing these is shaped into a sheet by a doctor blade method to produce a green sheet. The thickness of the green sheet is preferably 0.1 to 5 mm.

(2) Step of Printing Conductor Paste on Green Sheet A metal paste for forming the heating element 12 or a conductor paste containing conductive ceramic is printed on the green sheet 50 to form a conductor paste layer 120. Then, a conductive paste filling layer 130 for the through hole 13a is formed in the through hole. These conductive pastes contain metal particles or conductive ceramic particles.

The average particle diameter of the tungsten particles or molybdenum particles is preferably 0.1 to 5 μm. If the average particle size is less than 0.1 μm or more than 5 μm, it is difficult to print the conductive paste. As such a conductive paste, for example, 85 to 87 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 polyvinyl alcohol; A composition (paste) in which 1.5 to 10 parts by weight of at least one solvent selected from α-terpineol and glycol is mixed.

(3) Green Sheet Laminating Step The green sheet 50 on which the conductor paste is not printed is
The green sheet 50 on which the conductive paste is printed is laminated on and under the green sheet 50 (see FIG. 5A). At this time, the green sheets 50 on which the conductive paste is printed are stacked so that they are positioned at 60% or less of the thickness of the stacked green sheets. Specifically, the number of stacked green sheets on the upper side is preferably 20 to 50, and the number of stacked green sheets on the lower side is preferably 5 to 20.

(4) Green Sheet Laminate Firing Step The green sheet laminate is heated and pressed to sinter the green sheet and the internal conductive paste. The heating temperature is preferably from 1000 to 2000 ° C., and the pressure is preferably from 10 to 20 MPa. Heating is performed in an inert gas atmosphere. As the inert gas, for example, argon, nitrogen, or the like can be used.

Next, a semiconductor wafer 3 is placed on the obtained sintered body.
A through-hole 15 is formed through which a lifter pin 16 for supporting 9 is inserted. At this time, using a drill with a normal blade, after forming a cylindrical through hole, using a drill with a blade capable of forming a conical recess, from the heating surface side to the through hole portion By performing the processing, the through hole 15 including the columnar portion 15a and the enlarged diameter portion 15b can be formed. By the sandblasting process, a through hole having the above shape can be formed, and a through hole having a trapezoidal longitudinal section can also be formed.

The through-hole 15 is formed in the ceramic substrate 11
It is desirable to form them at substantially equal intervals on one circumference having a concentric circle relationship. Lifter pins 16 inserted into through holes 15 are widely dispersed on ceramic substrate 11 and
This is because the semiconductor wafer 39 can be kept more horizontal because the intervals are equal.

Further, a bottomed hole 14 for embedding a temperature measuring element such as a thermocouple is formed in the ceramic substrate (FIG. 5).
(B)). Thereafter, a blind hole 13b is formed to expose a through hole 13a for connecting the heating element 12 to the external terminal 13.
To form (See FIG. 5 (c))

The step of forming the bottomed holes and the through holes may be performed on the green sheet laminate, but is preferably performed on the sintered body. This is because during the sintering process, there is a possibility of deformation.

The formation of the through holes and the bottomed holes is usually performed after surface polishing. After that, the external terminal 13 is connected to the through hole 13a for connecting to the internal heating element 12, and is heated and reflowed. Heating temperature is 200-50
0 ° C. is preferred.

Further, a thermocouple (not shown) as a temperature measuring element is attached to the bottomed hole 14 with a silver solder, a gold solder, or the like, and sealed with a heat-resistant resin such as polyimide. The process ends (see FIG. 5D).

Next, a method of manufacturing the ceramic heater 20 in which the heating element 22 is formed on the bottom surface of the ceramic substrate 21 (see FIGS. 3 and 4) will be described with reference to FIG.

(1) Step of Manufacturing Ceramic Substrate The above-described ceramic powder such as nitride such as aluminum nitride or silicon carbide is added to yttria (Y ₂ O
₃ ) and sintering aids such as B ₄ C, compounds containing Na and Ca,
After preparing a slurry by blending a binder and the like, the slurry is granulated by a method such as spray drying, and the granules are molded into a plate by pressing into a mold,
A green form is produced.

Next, the formed body is heated, fired and sintered to produce a ceramic plate. After that, the ceramic substrate 21 is manufactured by processing into a predetermined shape, but may be a shape that can be used as it is after firing. By performing heating and firing while applying pressure, it is possible to manufacture a ceramic substrate 21 having no pores. Heating and firing may be performed at a sintering temperature or higher.
0 to 2500 ° C. In oxide ceramics,
1500 ° C to 2000 ° C.

Further, lifter pins 1 for supporting semiconductor wafer 39 are formed in the same manner as described above.
6 are formed. The method of forming the through holes is the same as in the case of the ceramic heater having a resistance heating element inside. Further, a bottomed hole 24 for embedding a temperature measuring element such as a thermocouple in the ceramic substrate is formed. (See FIG. 6 (a))

(2) Step of Printing Conductive Paste on Ceramic Substrate The conductive paste is generally a high-viscosity fluid composed of metal particles, resin and solvent. The conductor paste is printed on a portion where the heating element 22 is to be provided by screen printing or the like to form a conductor paste layer. The conductor paste layer is desirably formed such that the cross section of the heating element 22 after firing has a rectangular and flat shape.

(3) Firing of Conductive Paste The conductive paste layer printed on the bottom surface 21b of the ceramic substrate is heated and baked to remove the resin and the solvent, sinter the metal particles, and bake on the bottom surface of the ceramic substrate 21, The heating element 22 is formed (see FIG. 6B). The temperature of the heating and firing is preferably from 500 to 1000C. If the above-mentioned oxide is added to the conductor paste, metal particles,
Since the ceramic substrate and the oxide are sintered and integrated, the adhesion between the heating element 22 and the ceramic substrate 21 is improved.

(4) Formation of Metal Coating Layer Next, a metal coating layer 220 is formed on the surface of the heating element 22 (see FIG. 6C). The metal coating layer 220 can be formed by electrolytic plating, electroless plating, sputtering, or the like. However, considering mass productivity, electroless plating is optimal. (5) Attachment of terminals etc. Terminals (external terminals 23) for connection to a power supply are attached to the ends of the pattern of the heating element 22 by soldering. In addition, a thermocouple (not shown) is fixed to the bottomed hole 24 with a silver solder, a gold solder, or the like, and sealed with a heat-resistant resin such as polyimide, thereby completing the manufacture of the ceramic heater 20 (see FIG. 6D). ).

The ceramic heater of the present invention can be used as an electrostatic chuck by providing an electrostatic electrode inside a ceramic substrate. Further, by forming a chuck top conductor layer on the surface, it can be used as a ceramic substrate for a wafer prober.

[0109]

The present invention will be described in more detail with reference to the following examples. (Example 1) Production of ceramic heater (see FIGS. 1, 2 and 5) (1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Co., average particle size 0.6 μm), 4 parts by weight of alumina, acrylic resin binder Using a paste obtained by mixing 11.5 parts by weight, 0.5 part by weight of a dispersant, and 53 parts by weight of alcohol composed of 1-butanol and ethanol, green sheets having a thickness of 0.47 mm were formed by a doctor blade method. 50 were produced.

(2) Next, this green sheet 50 is
After drying at 0 ° C. for 5 hours, a portion to be a through hole 13a was provided by punching.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of an α-terpineol solvent, and 0.3 part by weight of a dispersant are mixed to form a conductor. Paste A was prepared.
Conductive paste B was prepared by mixing 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpineol solvent, and 0.2 parts by weight of a dispersant.

The conductor paste A is printed on a green sheet by screen printing, and the conductor paste layer 1 for the heating element is printed.
20 were formed. The printing pattern was a concentric pattern as shown in FIG. Further, a conductive paste B was filled into a portion to be a through hole 13a for connecting the external terminal 13, thereby forming a filling layer 130.

Green sheet 50 after the above processing
Further, 37 sheets of green sheets 50 on which no conductor paste was printed were laminated on the upper side (heating surface) and 13 sheets on the lower side, and pressed at 130 ° C. and a pressure of 8 MPa to form a laminate (FIG. 5). (A)).

(4) Next, the obtained laminate was degreased in nitrogen gas at 600 ° C. for 5 hours, and at 1890 ° C. under a pressure of 15 M
Hot pressing was performed at Pa for 10 hours to obtain a ceramic plate having a thickness of 4 mm. This was cut out into a 310 mm disk shape to obtain a ceramic plate having a heating element 12 with a thickness of 6 μm and a width of 10 mm inside.

(5) Next, after polishing the ceramic plate obtained in (4) with a diamond grindstone,
A bottomed hole 14 for inserting a thermocouple was formed. Further, a lifter pin 1 for transporting a semiconductor wafer or the like is provided.
6 (diameter: 3 mm) were formed with three through holes 15 (see FIG. 5B).

In the through hole 15, the diameter of the cylindrical portion 15a is 3.5 mm and its length is 2 mm, the depth (length) of the enlarged diameter portion 15b is 2 mm, and the diameter of the enlarged diameter portion 15b on the heating surface. Was 7 mm (see FIG. 2). Also, the through hole 1
5 is a diameter 2 which is concentric with the ceramic substrate 11.
They were formed on a circumference of 00 mm at equal intervals.

(6) Next, the portion where the through hole 13a is formed is cut out to form a blind hole 13b (FIG. 5).
(See FIG. 5 (c)), and the external terminal 13 made of Kovar was connected to the blind hole 13b by heating and reflowing at 700 ° C. using a gold solder made of Ni—Au (see FIG. 5 (d)).

(7) A thermocouple (not shown) for temperature control was buried in the bottomed hole 14 to complete the manufacture of the ceramic heater 10 of the present invention.

Example 2 Production of Ceramic Heater (See FIGS. 3, 4 and 6) (1) Aluminum Nitride Powder (Average Particle Size: 0.6 μm)
100 parts by weight, yttria (average particle size: 0.4 μm) 4
The composition consisting of parts by weight, 12 parts by weight of an acrylic binder and alcohol was spray-dried to prepare a granular powder.

(2) Next, this granular powder was put into a mold and molded into a flat plate to obtain a formed product (green).

(3) Next, this formed form was heated at 1800 ° C.
Hot pressing was performed at a pressure of 20 MPa to obtain an aluminum nitride plate having a thickness of 5 mm. Next, a disk having a diameter of 310 mm was cut out from the plate to obtain a ceramic plate (ceramic substrate 21). The ceramic substrate 21 is drilled and lifter pins 16 (diameter: 3
mm) into which a through hole 25 (diameter: 3.5 mm) is inserted.
And a bottomed hole 24 for embedding a thermocouple (see FIG. 6A).

In the through hole 15, the diameter of the cylindrical portion 15a is 3.5 mm and its length is 3 mm, the depth (length) of the enlarged diameter portion 15b is 2 mm, and the diameter of the enlarged diameter portion 15b on the heating surface. Was 10 mm (see FIG. 4). The through-holes 25 were formed at equal intervals on a circumference having a diameter of 40 mm and a concentric relationship with the ceramic substrate 21.

(4) Ceramic substrate 2 obtained in (3) above
1, a conductor paste layer was formed by screen printing.
The printing pattern was a concentric pattern shown in FIG. As the conductor paste, Ag 48% by weight, Pt
21 wt%, _SiO 2 1.0 _{wt%, B 2} O 3 1.2 wt%, ZnO4.1 wt%, PbO3.4 wt%, ethyl acetate 3.4 wt%, butyl carbitol 17.9 wt% A composition having the following composition was used. This conductor paste was an Ag-Pt paste, and the silver particles had a mean particle size of 4.5 μm and were scaly. Further, the Pt particles were spherical with an average particle diameter of 0.5 μm.

(5) After forming the conductive paste layer, the ceramic substrate 21 is heated and fired at 780 ° C.
Ag and Pt in the conductor paste were sintered and baked on the ceramic substrate 21 to form a heating element 22 (see FIG. 6B). The heating element 22 had a thickness of 5 μm, a width of 2.4 mm, and a sheet resistivity of 7.7 mΩ / □.

(6) Nickel sulfate 80 g / l, sodium hypophosphite 24 g / l, sodium acetate 12 g / l,
The ceramic substrate 21 prepared in the above (5) is immersed in an electroless nickel plating bath composed of an aqueous solution having a concentration of boric acid of 8 g / l and ammonium chloride of 6 g / l.
2 a 1 μm thick metal coating layer (nickel layer) 22
0 was precipitated (see FIG. 6 (c)).

(7) Next, a silver-lead solder paste (manufactured by Tanaka Kikinzoku Co., Ltd.) is printed by screen printing on the portion where the external terminal 23 for securing the connection to the power supply is to be attached, and the solder layer (not shown) is printed. Was formed. Next, the external terminals 23 made of Kovar were placed on the solder layer, and heated and reflowed at 420 ° C. to attach the external terminals 23 to the surface of the heating element 22. (See Fig. 6 (d))

(8) A thermocouple (not shown) for temperature control was sealed in the bottomed hole 24 with polyimide, and the production of the ceramic heater 20 of the present invention was completed.

Comparative Example 1 Manufacture of Ceramic Heater Similar to the conventional case, except that a cylindrical through hole (diameter: 3.5 mm) for inserting a lifter pin (diameter: 3.0 mm) was formed in a ceramic substrate. In the same manner as in Example 1, a ceramic heater was manufactured.

Comparative Example 2 Example 1 was repeated except that a plug made of AlN that could be fitted into the through hole was fitted into the through hole.
A ceramic heater was manufactured in the same manner as described above.

A silicon wafer was placed on the ceramic heaters according to Examples 1 and 2 and Comparative Examples 1 and 2 via lifter pins, and the temperature was raised to 300 ° C. by energizing, and evaluated by the following method. . The lifter pins protruded 50 μm from the heating surface of the ceramic heater, and the portion of the silicon wafer supported by the lifter pins was 50 μm away from the heating surface.

Evaluation Method (1) Uniformity of Temperature in Heating Surface During Heating The temperature of the ceramic heater was raised to 300 ° C. in 45 seconds while the silicon wafer with the thermocouple was placed thereon, and the silicon wafer was heated in the process of raising the temperature. The difference between the maximum and minimum temperatures was investigated. Table 1 shows the results.

(2) Particle Number of Silicon Wafer After the temperature of the ceramic heater was raised to 300 ° C.,
The number of particles generated on the silicon wafer was measured. Table 1 shows the results.

[0133]

[Table 1]

As is clear from Table 1, in the ceramic heater according to the example, the temperature of the silicon wafer at the time of temperature rise was uniform. On the other hand, in the ceramic heater according to Comparative Example 1, the temperature variation when the temperature of the silicon wafer was raised was large, and the temperature was decreased particularly at the portion corresponding to the portion where the through-hole was formed. This is because the ceramic heater according to Comparative Example 1 has a large heat capacity at the cooling spot portion because the through hole has a cylindrical shape and does not expand in the vicinity of the heating surface. It is considered that the temperature was lowered at a portion corresponding to the portion where was formed. On the other hand, in the ceramic heater of the embodiment, since the through-hole has a columnar shape and an enlarged diameter portion and is enlarged near the heating surface, the heat capacity of a portion where a cooling spot is easily generated is small. It is considered that the temperature of the silicon wafer did not easily vary. Further, in the ceramic heater according to Comparative Example 2, since a plug made of AlN was fitted in the through-hole and there was no portion where a cooling spot was likely to occur, the temperature of the silicon wafer at the time of temperature rise was uniform. there were.

In the ceramic heaters according to Examples 1 and 2 and Comparative Example 1, almost no particles were generated because the silicon wafer was mounted via the lifter pins. In the heater, the ceramic heater and the plug made of AlN slid during heating, and a large amount of particles were generated on the silicon wafer.

Example 3 In Example 3, a ceramic heater was manufactured in the same manner as in Example 1 except that the ratio of the diameter of the enlarged portion on the heating surface to the diameter of the columnar portion was changed. . Then, a silicon wafer with a thermocouple is placed on the manufactured ceramic heater via lifter pins,
The wafer was heated to 00 ° C., and the difference between the maximum temperature and the minimum temperature of the silicon wafer was examined. FIG. 8 shows the result.

In FIG. 8, ΔT on the vertical axis represents the temperature difference (° C.) between the maximum temperature and the minimum temperature of the silicon wafer, and the ratio of the horizontal axis represents the diameter of the enlarged portion on the heating surface of the ceramic heater. And the ratio to the diameter of the columnar portion (diameter of the enlarged diameter portion / diameter of the columnar portion).

As is apparent from FIG. 8, when the ratio of the diameter of the enlarged diameter portion on the heating surface to the diameter of the columnar portion is less than 1.2 or more than 10, the temperature difference ΔT of the silicon wafer becomes large. turn into.

[0139]

According to the ceramic heater for heating a semiconductor wafer or a liquid crystal substrate of the present invention, the diameter of the through hole formed in the ceramic substrate on the side of the heating surface for heating the object to be heated is opposite to that of the heating surface. Because it is larger than the diameter,
The proportion of the gas in the portion where the cooling spot occurs is increased, and the heat capacity is reduced. Therefore, the temperature of the semiconductor wafer, the liquid crystal substrate and the like near the through hole is hardly reduced, and the heating object such as the semiconductor wafer and the liquid crystal substrate can be more uniformly heated.

[Brief description of the drawings]

FIG. 1 is a bottom view schematically showing a ceramic heater of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the ceramic heater shown in FIG.

FIG. 3 is a bottom view schematically showing another example of the ceramic heater of the present invention.

4 is a partially enlarged cross-sectional view of the ceramic heater shown in FIG.

FIGS. 5A to 5D are cross-sectional views schematically showing a part of a manufacturing process of the ceramic heater shown in FIG.

FIGS. 6A to 6D are cross-sectional views schematically showing a part of a manufacturing process of the ceramic heater shown in FIG.

FIG. 7 is a bottom view of a conventional ceramic heater.

FIG. 8 shows a temperature difference (ΔT) of a silicon wafer when the silicon wafer is heated using the ceramic heater according to the third embodiment, and ((diameter of enlarged portion on heating surface) / (diameter of columnar portion)). 6 is a graph showing a relationship with the graph.

[Explanation of symbols]

 10, 20 Ceramic heater 11, 21 Ceramic substrate 11a, 21a Heating surface 11b, 21b Bottom surface 12, 22 Heating element 120 Conductive paste layer 130 Filling layer 13, 23 External terminal 13a Through hole 13b Bag hole 14, 24 Bottom hole 15, 25 through-hole 15a, 25a cylindrical portion 15b, 25b enlarged diameter portion 16, 26 lifter pin 220 metal coating layer 39 semiconductor wafer 50 green sheet

Claims (3)

[Claims] A ceramic heater for heating a semiconductor wafer or a liquid crystal substrate, wherein a heating element is formed on the surface or inside of a disk-shaped ceramic substrate, and a through-hole for inserting a lifter pin through the ceramic substrate is provided. The semiconductor heater for heating a semiconductor wafer or a liquid crystal substrate, wherein the diameter of the through-hole on the heating surface side for heating the object to be heated is larger than the diameter on the opposite side of the heating surface. 2. The ceramic heater for heating a semiconductor wafer or a liquid crystal substrate according to claim 1, wherein said through-hole comprises a cylindrical portion and a diameter-enlarging portion whose diameter increases as approaching a heating surface. 3. The diameter of the through hole on the heating surface side is 1.2 to 10 times the diameter on the opposite side of the heating surface.
Or the ceramic heater for heating a semiconductor wafer or a liquid crystal substrate according to 2.