JP2002246286A - Ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater constituted in a structure that even in the case where a support pin is provided in a ceramic substrate to hold a semiconductor wafer at a constant distance apart from the heating surface of the ceramic substrate, a warpage and the like are not generated in the ceramic substrate and the whole semiconductor wafer can be heated at a uni form temperature. SOLUTION: A ceramic heater is constituted in such a structure that a heating unit is formed in the surface or the interior of a ceramic substrate and the ceramic heater is characterized in that the heater is constituted in such a structure that a recessed part is provided in the heating surface of the substrate and a support pin is inserted and fixed in the recessed part via a C-ring.

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 as an apparatus for manufacturing and inspecting a semiconductor, for example, for drying a photosensitive resin applied on a semiconductor wafer.

[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.

However, in such a heater, an object to be heated, such as a semiconductor wafer, is placed in contact with the ceramic substrate, and the temperature distribution on the surface of the ceramic substrate is reflected on the semiconductor wafer, and the semiconductor wafer is exposed. Etc. could not be heated at a uniform temperature. Further, in order to heat the semiconductor wafer or the like at a uniform temperature, if the surface temperature of the ceramic substrate is to be made uniform, very complicated control is required, and it is not easy to control the temperature.

Therefore, as shown in FIG. 9, the present applicant first forms a through-hole 37 in which holes having different diameters communicate with each other as shown in FIG. After the support pins 48 having the shape shown in FIG. 9 are inserted so as to protrude slightly from the surface of the ceramic substrate 31 via the support pins 48, the support pins 48 having a shape shown in FIG. 9 are fixed. A method has been proposed in which the semiconductor wafer 19 is held at a distance from the semiconductor wafer 19 and the semiconductor wafer 19 is heated.

As described above, when the support pins 48 are provided so as to slightly protrude from the surface of the ceramic substrate and the semiconductor wafer 19 is held by the support pins 48, the semiconductor wafer is moved at a predetermined distance from the surface of the ceramic substrate. Since the semiconductor wafer can be held in a separated state, the semiconductor wafer is heated by radiation or convection from the ceramic substrate. Therefore, usually, the temperature distribution on the surface of the ceramic substrate is not directly reflected on the semiconductor wafer, and the semiconductor wafer is heated more uniformly, and the temperature distribution is hardly generated on the semiconductor wafer.

[0007]

However, in the above-described method, a plurality of through holes 37 are formed in the ceramic substrate 31 and the support pins 48 are fixed using the through holes 37. When the silicon wafer 19 is to be heated using such a method, the strength of the ceramic substrate 31 is reduced due to the formation of the through holes 37. In particular, in a high-temperature region of 100 ° C. or higher, the strength is greatly reduced. As a result, the ceramic substrate 31 is slightly warped and the flatness is reduced, and the distance between the silicon wafer and the heating surface differs depending on the location. Therefore, there is a problem that the silicon wafer 19 may not be heated at a uniform temperature.

[0008]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of examining a method of holding the semiconductor wafer at a constant distance from the substrate surface without lowering the strength of the ceramic substrate, a recess was provided on the ceramic substrate heating surface, and the support pins were fixed in the recess. By adopting the method, the support pins can be provided without deteriorating the strength of the ceramic substrate, so that even in a high-temperature region, the semiconductor wafer can be heated at a uniform temperature. It was completed.

That is, a ceramic heater according to a first aspect of the present invention is a ceramic heater having a heating element formed on the surface or inside of a ceramic substrate, wherein a concave portion is provided on a heating surface of the ceramic substrate, and the concave portion is provided in the concave portion. A support pin is inserted and fixed via a C-ring.

A ceramic heater according to a second aspect of the present invention is a ceramic heater having a heating element formed on the surface or inside of a ceramic substrate, wherein a concave portion is provided on a heating surface of the ceramic substrate, and the concave portion is provided in the concave portion. The support pin is fitted and fixed.

According to the first and second ceramic heaters of the present invention, since the ceramic substrate for fixing the support pins is not a through hole but a concave portion, the strength of the ceramic substrate is low. Does not drop. That is,
When a through-hole is formed, the ceramic layer does not exist at all in the through-hole, so that the strength at a high temperature is greatly reduced. However, when the concave portion is formed, the ceramic layer exists under the concave portion, and the ceramic layer does not break at this portion.

Therefore, the ceramic heater is, for example, 1
Even when heated to 00 ° C. or more, warpage due to the influence of gravity or the like hardly occurs on the ceramic substrate, and the flatness is maintained.
Therefore, the distance between the semiconductor wafer and the ceramic substrate is substantially constant over the entire heating surface of the ceramic substrate, and the semiconductor wafer can be heated at a uniform temperature. Also,
In the present invention, since the semiconductor wafer is supported via the support pins, impurities caused by the sintering aid such as an alkali metal do not migrate from the ceramic substrate surface to the semiconductor wafer, and the semiconductor wafer is not contaminated. . Furthermore, since the support pins are fixed to the concave portions, unlike the case where the support pins are fixed to the through holes, the support pins do not fall off due to an accident or the like.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a ceramic heater according to a first embodiment of the present invention will be described. A ceramic heater according to a first aspect of the present invention is a ceramic heater in which a heating element is formed on a surface or inside of a ceramic substrate, a concave portion is provided on a heating surface of the ceramic substrate, and the concave portion is provided via a C-ring. The support pin is inserted and fixed.

FIG. 1 is a plan view schematically showing an example of the ceramic heater according to the first aspect of the present invention, and FIG.
FIG. 2B is a partially enlarged cross-sectional view showing a part thereof.
FIG. 2 is a perspective view showing a state in which a support pin is inserted into and fixed to the ceramic heater shown in FIG. 1 via a C-ring. In this ceramic heater 10, a resistance heating element 1 composed of a plurality of circuits is provided inside a ceramic substrate 11 formed in a disk shape.
2 are formed in a concentric pattern. In addition, these resistance heating elements 12 are connected so that double concentric circles close to each other are sequentially connected as a set of circuits by a resistance heating element formed of a straight line, thereby forming a single line. The circuit is configured.

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.

In a portion near the center of the ceramic substrate 11, a lifter pin through hole 15 for inserting a lifter pin for supporting the silicon wafer 19 when the silicon wafer 19 is delivered or the like is provided. A bottomed hole 14 for inserting and fixing a temperature measuring element such as a thermocouple is formed in the bottom surface of the device.

Further, a plurality of recesses 17 are provided on the heating surface of the ceramic substrate 11, and support pins 18 are fixed to the recesses 17 via C-rings 29. As shown in FIG. 1, these support pins 18 are relatively non-heat-generating regions in the outer peripheral portion, and four are provided at a portion on the circumference of the concentric circle and one at the center of the ceramic substrate 11. Are provided in total. The four support pins 18 located on the circumference of the concentric circle are provided at positions to be rotated.

As described above, in the first aspect of the present invention, a concave portion is provided on the heating surface of the ceramic substrate, and the support pin is inserted and fixed into the concave portion via the C-ring. The diameter of this recess is 1-1.
00 mm is desirable, and 2 to 10 mm is more desirable. This is because if it is too large, a cooling spot is generated.

The depth of the concave portion is one of the thickness of the ceramic substrate.
0-90% is desirable. This is because if the recess is too deep, the strength of the ceramic substrate is reduced, so that the flatness is reduced.

The shape of the concave portion in plan view is not particularly limited, and may be triangular or square, but is preferably circular. This is because the support pins are fixed via the C-ring.

The number of recesses is preferably 5 to 8 when the diameter of the ceramic substrate is about 210 mm, and 5 to 10 when the diameter is about 300 mm. If the number of the support pins is too small, the distance between the support pins becomes too wide, and the silicon wafer bends. As a result, the distance between the silicon wafer and the ceramic substrate varies, and the entire silicon wafer becomes uniform. Heating becomes difficult. on the other hand,
This is because if the number of the support pins is too large, there are problems in terms of the complexity of the manufacturing process and the manufacturing cost.

As for the position of the concave portion, it is desirable that the concave portion is widely dispersed on the ceramic substrate and provided at a position to be rotated with respect to the center. By providing the support pins in such a form, when the silicon wafer is heated, the silicon wafer does not bend, the distance between the silicon wafer and the ceramic substrate becomes uniform, and the silicon wafer can be heated uniformly. It is.

On the other hand, when the concave portions are unevenly distributed on the ceramic substrate and / or are provided at irregular intervals, a portion where the concave portions are widely formed is formed, and the semiconductor wafer is bent at the portion. As a result, the distance between the silicon wafer and the ceramic substrate becomes non-uniform, making it difficult to heat the silicon wafer uniformly.

Specifically, for example, as shown in FIG. 1, a plurality of concave portions are provided at equal intervals on the concentric circle of the ceramic substrate in a region which is a relatively outer peripheral portion of the ceramic substrate. An arrangement in which one concave portion is provided in the center portion of the ceramic substrate, or, as shown in FIG. And a plurality of recesses are provided on the circumference of the ceramic substrate so as to be rotated with respect to the center, and one recess is provided at the center of the ceramic substrate.

It is desirable that the recess be formed as far as possible from the resistance heating element in a region where the resistance heating element is not formed. This is because, when the concave portion is provided adjacent to the resistance heating element, there is a possibility that uniform heat transfer is prevented in the ceramic substrate.

A support pin is fixed to the recess through a C-ring. The C-ring is a C-shaped spring as shown in FIG. 2 (b).
When inserted into the recess 17, it is fixed in contact with the inner wall of the recess 17. Although the configuration of the support pin will be described in detail later, generally, the support pin is formed integrally with a columnar body and a fixed portion formed at the lower end of the columnar body and having a diameter larger than the columnar body. When the C-ring is inserted into the concave portion and fixed by pressing it against the fixing portion of the support pin, the fixing portion is pressed by the C-ring, so that the support pin is securely fixed in the concave portion. . The C-ring is preferably made of metal, particularly stainless steel, a Ni alloy, or the like, which does not easily rust.

Next, the support pins will be described. FIG.
(A) And (b) is the front view which showed typically the support pin provided in a recessed part in the ceramic heater of 1st this invention.

The following are conceivable as the support pins. The support pin 18 shown in FIG. 3A has a columnar portion 181 having a cone at its tip and in contact with the semiconductor wafer, and a columnar portion 1.
A fixed portion 182 formed at the lower end of 81 and having a diameter larger than the columnar portion 181 is integrally formed. Further, the support pin 28 shown in FIG. 3B has a columnar portion 281 having a semicircular sphere in contact with the semiconductor wafer at the tip,
The diameter formed at the lower end of the column 281 is
A fixing portion 282 larger than 1 is integrally formed.

As described above, the columnar body constituting the support pin may have a shape based on a cylinder and a cone.
A shape based on a cylinder and a hemisphere may be used. Further, a shape based on a prism and a pyramid, for example, a shape based on a triangular prism and a triangular pyramid, a shape based on a square prism and a quadrangular pyramid, and the like may be used, but a shape based on a cylinder and a cone, Alternatively, a shape based on a cylinder and a hemisphere is preferable. This is because the C-ring can be inserted smoothly.

The fixing portions 182 and 282 are desirably cylindrical. This is because a shape that fits into the recess is preferable. Further, the height of the fixing portions 182 and 282 needs to be smaller than the depth of the concave portion. This is because the C-ring needs to fit in the recess.

It is desirable that the support pin has a spire or semispherical tip such as a cone. This is because, when the semiconductor wafer is placed on the support pins, the semiconductor wafer comes into point contact with the semiconductor wafer and no hot spot or the like is formed on the semiconductor wafer.

The support pins of the ceramic heater according to the first aspect of the present invention are desirably made of ceramic, and are made of an oxide ceramic such as alumina or silica, which has a low thermal conductivity, in order to prevent the generation of hot spots and the like. Desirably.

In the above ceramic heater, it is desirable that the support pins protrude from the heating surface of the ceramic substrate at the same height. If the heights of the support pins are all the same, when the semiconductor wafer is placed, the semiconductor wafer becomes parallel to the heating surface of the ceramic substrate, and all the support pins support the semiconductor wafer. Does not occur. As a result, the distance between the semiconductor wafer and the ceramic substrate becomes uniform, and the semiconductor wafer can be uniformly heated. On the other hand, when the protruding heights of the support pins are different, the semiconductor wafer is tilted, and the support pins having a low height do not come into contact with the semiconductor wafer, so that bending occurs. As a result, the distance between the semiconductor wafer and the ceramic substrate varies, making it difficult to uniformly heat the semiconductor wafer.

In the first aspect of the present invention, when the silicon wafer is supported by the support pins, the height of the support pins is 5 to 50 from the surface or the heating surface of the ceramic substrate.
It is desirable that the height be 00 μm, particularly 5 to 500 μm. When the separation height is less than 5 μm, the temperature of the semiconductor wafer becomes non-uniform due to the influence of the temperature distribution of the ceramic substrate, and when it exceeds 5000 μm, the temperature of the semiconductor wafer hardly rises. This is because the temperature difference increases.

When the pillar portion of the support pin is cylindrical, the diameter is preferably 0.5 to 10 mm. If the size is too small, there is a risk of breakage when the semiconductor wafer is placed, and if the size is too large compared to the fixed portion, the C-ring cannot be inserted. It is desirable that the fixing portion of the support pin has a shape and a size that can fit into the concave portion. This is because if the fixing portion is too small compared to the size of the recess, the support pin is not stable.

In the ceramic heater according to the first aspect of the present invention, the resistance heating element may be provided inside the ceramic substrate as shown in FIG. 1, or may be provided outside the ceramic substrate. Is also good.

The pattern of the resistance heating element is not particularly limited. For example, double concentric circles close to each other as shown in FIG. 1 may be connected as a set of circuits by a linear resistance heating element. Are connected so as to form a single line, and a pattern in which a series of circuits are formed, as shown in FIG. 22l are formed therein, and a resistance heating element 2 having a concentric pattern is formed therein.
A pattern in which 2m to 22p are formed can be considered.

A repetitive pattern of a circular arc in which a concentric pattern is divided into a plurality of straight lines including the center, and adjacent circuits are connected by bending lines, respectively. Further, for example, a spiral pattern, an eccentric pattern, a repeated pattern of bent lines, and the like can also be used.
These may be used together, or they may be used in combination with a part of the pattern shown in FIG. 1 or FIG.

When the resistance heating element is provided, it may be formed on the surface (bottom surface) of the ceramic substrate as described above.
It may be embedded inside a ceramic substrate. When the heating element is formed inside the ceramic substrate, it is desirable that the resistance heating element is 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 temperature is too close to the heating surface, so that the heat propagating in the ceramic substrate is not sufficiently diffused, and a temperature variation occurs on the heating surface.

When the resistance heating element is formed inside the ceramic substrate, a plurality of resistance heating element forming layers may be provided. In this case, it is desirable that the resistance heating element is formed in some layer so as to complement each other, and that the pattern is formed in any region when viewed from above the heating surface. As such a structure, for example, a structure in which the staggered arrangement is provided. Note that the resistance heating element may be provided inside the ceramic substrate, and the resistance heating element may be partially exposed.

When a resistance heating element is provided on the surface of the ceramic substrate, the heating surface is desirably opposite to the surface on which the resistance heating element is formed. 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 resistance 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. The method of sintering the metal particles on the surface of is preferred. The sintering of the metal is sufficient if the metal particles and the metal particles and the ceramic are fused.

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

When a resistance heating element is formed inside the ceramic substrate 11, the width of the resistance heating element should be 5-20.
μm is preferred. When a resistance heating element is formed on the surface of the ceramic substrate 11, the width of the resistance heating element is set to 0.1 mm.
1-20 mm is preferable, and 0.1-5 mm is more preferable.

Although the resistance value of the resistance heating element can be varied depending on its width and thickness, the above range is most practical. The resistance value increases as the resistance value decreases and the resistance value decreases. The thickness and width of the resistance heating element when formed inside the ceramic substrate are larger, but when the resistance heating element is provided inside, the distance between the heating surface and the heating element becomes shorter, and the surface temperature becomes lower. Since the uniformity is reduced, it is necessary to increase the width of the resistance heating element itself.In order to provide the resistance heating element inside, there is no need to consider adhesion with nitride ceramics or the like. A high melting point metal such as molybdenum or a carbide such as tungsten or 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 resistance heating element has the above-described thickness and width.

By setting the formation position of the resistance heating element in this way, the heat generated from the resistance heating element is diffused throughout the ceramic substrate while the heat is being propagated, and the object to be heated (semiconductor wafer) is heated. The temperature distribution on the surface is made uniform, and as a result, the temperature in each part of the object to be heated is made uniform.

Further, in the pattern of the resistance heating element in the ceramic heater of the present invention, as shown in FIG. 4, the resistance heating element pattern formed on the outermost periphery is a pattern divided in the circumferential direction. Thus, it is possible to perform fine temperature control at the outermost periphery of the ceramic heater whose temperature tends to decrease, and it is possible to suppress variations in the temperature of the ceramic heater. Furthermore, the pattern of the resistance 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 resistance 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 resistance heating element / the thickness of the resistance heating element) is 10 to 5000.
It is desirable that By adjusting to this range, the resistance value of the resistance heating element can be increased, and the uniformity of the temperature of the heating surface can be ensured.

When the thickness of the resistance heating element is constant, if the aspect ratio is smaller than the above range, the amount of heat transmission in the direction of the heating surface of the ceramic substrate becomes small, and the heat distribution approximates the pattern of the resistance heating element. If the aspect ratio is too large, on the other hand, if the aspect ratio is too large, the temperature immediately above the center of the resistance heating element will be high, and eventually, a heat distribution similar to the pattern of the resistance heating element will occur on the heating surface. Would. Therefore, considering the temperature distribution, the aspect ratio of the cross section is 1
It is preferably from 0 to 5000.

When the resistance heating element is formed on the surface of the ceramic substrate, the aspect ratio is desirably 10 to 200. When the resistance heating element is formed inside the ceramic substrate, the aspect ratio is desirably 200 to 5000.

When the resistance heating element is formed inside the ceramic substrate, the aspect ratio becomes larger. However, when the resistance heating element is provided inside, the distance between the heating surface and the resistance heating element becomes shorter. This is because the temperature uniformity of the surface is reduced, and it is necessary to flatten the resistance heating element itself.

Further, when forming a resistance heating element,
The conductive paste is not particularly limited, but preferably contains not only metal particles or conductive ceramic for ensuring conductivity, but also a resin, a solvent, a thickener, and the like.

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.

Although 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 flakes or a mixture of spheres and flakes, the metal oxide between the metal particles is easily retained, and the adhesion between the resistance heating element and the nitride ceramic or the like is improved. And it is advantageous because 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 desirable that the conductive paste is obtained by adding a metal oxide to metal particles and sintering the metal particles and the metal oxide as a resistance heating element.
Thus, by sintering the metal oxide together with the metal particles, it is possible to bring the nitride ceramic or the carbide ceramic, which is the ceramic substrate, into close contact with 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 surfaces of the metal particles and the surfaces 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, oxidized
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 resistance 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 resistance heating element. As the metal foil, it is preferable to use a nickel foil or a stainless steel foil as a resistive heating element by patterning 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 resistance heating element is formed is preferably 1 mΩ / □ to 10 Ω / □. When the area resistivity is less than 1 mΩ / □, the resistivity is too small and the calorific value is too small to function as a resistance heating element. On the other hand, when the area resistivity exceeds 10 Ω / □, the applied voltage On the other hand, the calorific value becomes too large, and it is difficult to control the calorific value of the ceramic substrate provided with the resistance heating element on the surface of the ceramic substrate. From the viewpoint of controlling the heat generation, the area resistivity of the resistance heating element is 1 to 50 mΩ / □.
Is more preferred. However, when the area resistivity is increased,
Since the pattern width (cross-sectional area) can be increased and the problem of disconnection hardly occurs, in some cases, 50 mΩ
/ □ may be preferable in some cases.

When the resistance heating element is formed on the surface of the ceramic substrate 21, it is desirable that a metal coating layer (see FIG. 5) 220 be formed on the surface of the resistance 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 preferably 0.1 to 10 μm.

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 resistance heating element requires a terminal for connection to a power supply, and this terminal is attached to the resistance heating element via solder. Nickel prevents thermal diffusion of solder. Examples of the connection terminal include an external terminal 13 made of Kovar.

When the resistance heating element is formed inside the ceramic substrate 11, no coating is necessary since the surface of the resistance heating element is not oxidized. When the resistance heating element is formed inside the ceramic substrate 11, a part of the resistance heating element may be exposed on the surface, and a through hole for connecting the resistance heating element is provided in the terminal portion. The terminals may be connected and 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 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 the ceramic heater, the larger the diameter of the semiconductor wafer in which the deflection is likely to occur, and the more effective the configuration of the present invention functions. The diameter of the ceramic substrate is particularly preferably 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

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. If the thickness is more than 5 mm, the heat is difficult to propagate, and the heating efficiency tends to decrease. 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 the temperature of the semiconductor wafer can be measured more accurately.

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.

As shown in FIG. 1, it is desirable 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 above temperature measuring element may be adhered to the bottom of the bottomed hole using gold brazing or silver brazing, or may be inserted into the bottomed hole and then 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 solder, 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 ceramic forming the ceramic heater of the present invention is preferably a nitride ceramic or a carbide ceramic. Nitride ceramics and carbide ceramics have a lower 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, it does not warp or warp due to heating .
Therefore, the ceramic substrate can be made thin and light. Furthermore, the thermal conductivity of the ceramic substrate is high,
Since 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 above-mentioned 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.

[0082] 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.

Further, the ceramic substrate may contain a sintering aid. As the sintering aid, for example,
Examples thereof include alkali metal oxides, alkaline earth metal oxides, and rare earth oxides. Among these sintering aids,
_{CaO, Y 2 O 3, Na} 2 O, Li 2 O, Rb 2 O are preferred. Their content is 0.1 to 20% by weight.
Is preferred. Further, it may contain alumina. The porosity of the ceramic substrate is preferably 0 or 5% or less. This is because mechanical strength is high and insulation properties are excellent.

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 secured.

As the insulating layer, an oxide ceramic is desirable, and 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 ensured, and if it exceeds 1000 μm, the thermal conductivity from the heating element to the ceramic substrate is hindered. 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.

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 brightness of the ceramic substrate is 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
0, each color is divided into 10 between these black lightness and white lightness so that the perception of the brightness of the color becomes the same rate, and displayed 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.

According to the ceramic heater of the first aspect of the present invention, since the portions formed on the surface of the ceramic substrate for fixing the support pins are not the through holes but the concave portions, the strength of the ceramic substrate does not decrease. In addition, the ceramic substrate is not warped, and the flatness is kept constant. Accordingly, the distance between the semiconductor wafer and the heating surface of the ceramic substrate is substantially constant, and the entire semiconductor wafer can be heated at a uniform temperature.

Next, the ceramic heater according to the second embodiment of the present invention will be described. The ceramic heater according to the second aspect of the present invention comprises:
A ceramic heater having a heating element formed on the surface or inside of a ceramic substrate, wherein a recess is provided on a heating surface of the ceramic substrate, and a support pin is fitted and fixed in the recess. Things.

FIG. 4 is a bottom view schematically showing an example of the second ceramic heater of the present invention, and FIG.
FIG. 5B is a partially enlarged cross-sectional view showing a part thereof, and FIG.
FIG. 5 is a perspective view schematically showing how the support pins are fixed to the ceramic substrate in the ceramic heater shown in FIG. 4.

In the ceramic heater 20, the ceramic substrate 21 is formed in a disk shape, and resistance heating elements 22 a to 22 h having a repeated pattern of eight divided bending lines are formed on the outermost surface of the surface of the ceramic substrate 21. On the inner side, resistance heating elements 22i to 22l each formed of a repetitive pattern of four divided bent lines are formed, and further inside, resistance heating elements 22m to 22p formed of concentric patterns are arranged at equal intervals. External terminals 23 serving as input / output terminals are connected to both ends of each resistance heating element via a metal coating layer 220.
In addition, a socket (not shown) having a conductive wire is attached to the external terminal 23, and the conductive wire is connected to a power supply or the like.

Further, a lifter pin through hole 25 for inserting a lifter pin 16 for carrying the semiconductor wafer 19 or the like is formed in a portion near the center of the ceramic substrate 21, and a temperature measurement hole is formed on the bottom surface 21 b. A bottomed hole 24 for inserting an element (not shown) is formed.

Further, a plurality of recesses 27 are provided on the heating surface of the ceramic substrate 21, and support pins 38 are fitted and fixed in the recesses 27. These recesses 27 are relatively non-heating element forming regions in the outer peripheral portion, four in the portion on the circumference of the concentric circle, four in the portion inside the concentric circle, and the central portion of the ceramic substrate 21. And one in total.

As described above, in the second aspect of the present invention, the concave portion is provided in the ceramic substrate, and the support pin is fitted and fixed in the concave portion. The shape of the concave portion in plan view is not particularly limited, and may be a circular shape, or may be a shape based on a square, for example, a triangular shape, a square shape, or the like.

When the shape of the concave portion in a plan view is circular, the diameter is preferably 0.5 to 10 mm. If the recess is too small, it will be difficult to insert the support pin,
The support pins are likely to break when inserted and fitted.

The depth of the concave portion is one of the thickness of the ceramic substrate.
0-90% is desirable. As in the first aspect of the present invention, if it is too deep, the strength of the ceramic substrate is reduced, so that the flatness is reduced. If it is too shallow, the support pins may come off from the concave portions. In the second aspect of the present invention, since the support pins are fitted and fixed without using metal fittings, springs and the like, it is preferable that the support pins are somewhat deeper than the recesses according to the first aspect of the present invention. This is because the contact area between the support pin and the concave portion increases, and the support pin is less likely to come off.

The number of recesses is preferably 5 to 8 when the diameter of the ceramic substrate is about 210 mm, and 5 to 10 when the diameter is about 300 mm. If the number of the support pins is too small, the distance between the support pins is too wide, and the silicon wafer is bent. As a result, the distance between the silicon wafer and the ceramic substrate varies, and the entire silicon wafer is uniformly formed. Heating becomes difficult. On the other hand, if the number of support pins is too large, there are problems in terms of complexity of the manufacturing process and manufacturing cost.

As for the position of the concave portion, it is preferable that the concave portion is widely dispersed on the ceramic substrate and provided at a position to be rotated with respect to the center. By providing the support pins in such a form, when the silicon wafer is heated, the silicon wafer does not bend, the distance between the silicon wafer and the ceramic substrate becomes uniform, and the silicon wafer can be heated uniformly. It is.

On the other hand, if the concave portions are unevenly distributed on the ceramic substrate and / or if the concave portions are provided at irregular intervals, a portion where the interval between the concave portions is large is formed, and bending occurs in the semiconductor wafer at that portion. As a result, the distance between the silicon wafer and the ceramic substrate becomes non-uniform, making it difficult to heat the silicon wafer uniformly.

More specifically, similarly to the first embodiment of the present invention, for example, as shown in FIG.
An arrangement in which a plurality of concave portions are provided at equal intervals and one concave portion is provided at the center of the ceramic substrate, or a circle which is concentric with the ceramic substrate in a region which is a relatively outer peripheral portion of the ceramic substrate as shown in FIG. A plurality of recesses are provided at equal intervals on the circumference and on the circumference of concentric circles on the inner circumference, and one recess is provided at the center of the ceramic substrate.

Further, as in the first aspect of the present invention, it is desirable that the recess is formed at a position as far as possible from the resistance heating element in a region where the resistance heating element is not formed. The recess
This is because, if provided adjacent to the resistance heating element, uniform heat transfer may be hindered in the ceramic substrate.

FIG. 6 is a front view schematically showing a support pin according to the second invention. Although the shape of the support pin 38 is not particularly limited, as shown in FIG. 6, a spire portion 38a and a column
8b. This support pin 38 does not have a fixing portion unlike the first invention,
The support pins 38 are inserted and fitted into the recesses 27 formed in the ceramic substrate 21 and fixed without using metal fittings, springs and the like.

The shape of the support pin may be a shape based on a cylinder and a cone, or may be a shape based on a cylinder and a hemisphere. In addition, shapes based on prisms and pyramids, for example, shapes based on triangular prisms and pyramids, shapes based on quadrangular prisms and square pyramids, and the like may be used. In order to fit and fix the concave portion, it is necessary that the concave portion has the same shape as the planar view.

Since the tip of the support pin 38 is spire or hemispherical, it comes into point contact with the silicon wafer mounted on the ceramic substrate provided with the support pin, and no hot spot or the like is formed on the silicon wafer. . The material of the support pin is the same as that of the first invention.

In the ceramic heater according to the second aspect of the present invention, it is preferable that the support pins protrude from the heating surface of the ceramic substrate at the same height as in the case of the first aspect of the present invention. If the heights of the support pins are all the same, when the semiconductor wafer is placed, the semiconductor wafer becomes parallel to the heating surface of the ceramic substrate, and all the support pins support the semiconductor wafer. Does not occur. As a result, the distance between the semiconductor wafer and the ceramic substrate becomes uniform, and the semiconductor wafer can be uniformly heated. On the other hand, if the protruding heights of the support pins are different,
The semiconductor wafer is tilted, and the supporting pins having a low height do not come into contact with the semiconductor wafer, so that bending occurs. As a result, the distance between the semiconductor wafer and the ceramic substrate varies, making it difficult to uniformly heat the semiconductor wafer.

In the second aspect of the present invention, the height of the support pins is, as in the first aspect of the invention, when the semiconductor wafer is supported by the support pins, and the height of the silicon wafer is five to five from the surface of the ceramic substrate or the heating surface. It is desirable that the height be 5000 μm, particularly 5 to 500 μm. The separation height is 5μ
If it is less than m, the temperature of the semiconductor wafer will be 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 will not easily rise, and as a result, the temperature difference of the semiconductor wafer will increase. Because.

In the ceramic heater according to the second aspect of the present invention, the resistance heating element may be provided inside the ceramic substrate as shown in FIG. 1, or may be provided as shown in FIG. It may be provided outside the ceramic substrate.

The pattern of the resistance heating element is not particularly limited, and includes the same pattern as that of the first embodiment of the present invention, and the same shape and material. Further, the characteristics such as the shape and material of the ceramic substrate constituting the ceramic heater of the second present invention are the same as those of the first present invention, so that the description thereof is omitted here.

According to the ceramic heater of the second aspect of the present invention, since not the through hole but the concave portion is formed on the surface of the ceramic substrate for fixing the support pin, the strength of the ceramic substrate can be reduced even in a high temperature region. As a result, the ceramic substrate does not warp and the flatness is kept constant. Therefore, the distance between the semiconductor wafer and the heating surface of the ceramic substrate is substantially constant, and the entire semiconductor wafer can be heated at a uniform temperature.

Next, a method for manufacturing the ceramic heater of the first invention and the ceramic heater of the second invention will be described. Since the ceramic heater of the first invention and the ceramic heater of the second invention are different only in the shape of the support pins and otherwise the same, the two inventions are put together to produce the ceramic heater of the invention. This will be described as a method. First, the resistance heating element 1 is placed inside the ceramic substrate 11.
A method of manufacturing the ceramic heater (see FIGS. 1 and 2) in which No. 2 is formed will be described with reference to FIG.

(1) Step of Manufacturing 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 manufactured using the paste.

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

As the solvent, at least one selected from α-terpineol and glycol is desirable. A paste obtained by mixing these is formed into a sheet shape by a doctor blade method to produce a green sheet 50. The thickness of the green sheet is preferably 0.1 to 5 mm.

(2) Step of Printing Conductive Paste on Green Sheet A metallic paste for forming the resistance heating element 12 or a conductive paste containing conductive ceramic is printed on the green sheet 50 to form the conductive paste layer 120. The conductive paste filling layer 130 for the through hole 13a is formed in the through hole.
To form 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 conductor paste is printed is laminated on and under the green sheet 50 (see FIG. 7A). 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) Step of firing green sheet laminate The green sheet laminate is heated and pressed to sinter the green sheet and the conductive paste therein. 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.

The obtained sintered body is subjected to blasting such as sand blasting to form a concave portion 17 in which a support pin 18 is provided (see FIG. 7B). In FIG. 7B,
Although the size of the concave portion 17 is considerably large, it is actually smaller than the size of the ceramic substrate 11.

It is desirable that the concave portions 17 are formed so that the support pins 18 are widely dispersed on the ceramic substrate 11 and are located at positions to be rotated with respect to the center of the ceramic substrate 11.

The lifter pin through hole 1 into which the lifter pin 16 for supporting the semiconductor wafer 19 is inserted is provided.
5. A bottomed hole 1 for embedding a temperature measuring element such as a thermocouple
4. A blind hole or the like that exposes the through hole 13a is formed (see FIG. 7C).

The step of forming the bottomed holes and the concave portions 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 through holes and the concave portions can be formed by performing blasting such as sand blasting after surface polishing. Further, an external terminal 13 is connected to a through-hole 13a for connecting to the internal resistance heating element 12, and is heated and reflowed. Heating temperature is 200-7
00 ° C. is preferred.

Next, 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.
Seal with heat resistant resin such as polyimide. Also, recess 1
7, the support pin 18 is inserted and fixed using the C-ring 29, and the production of the ceramic heater 10 is completed (FIG. 7).
(D)). The support pin shown in FIG. 6 may be inserted into the concave portion, fitted therein, and fixed.

Next, a ceramic heater 20 having a resistance heating element 22 formed on the bottom surface of a ceramic substrate 21 (see FIGS. 4 and 5).
8) will be described with reference to FIG.

(1) Step of Producing Ceramic Substrate The above-mentioned 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,
1500-2000 ° C.

The obtained ceramic substrate 21 is subjected to blasting such as sand blasting to form a recess 27.
It is desirable that the concave portions 27 are formed so that the support pins 28 are widely dispersed on the ceramic substrate 21 and are rotated about the center of the ceramic substrate 21.

Further, drilling or the like is performed to form a portion serving as a lifter pin through hole 25 for inserting a lifter pin 16 for supporting the semiconductor wafer 19 or a bottomed hole for embedding a temperature measuring element such as a thermocouple. 24 is formed. (See FIG. 8A).

(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. This conductor paste is printed on a portion where the resistance heating element 22 is to be provided by screen printing or the like, thereby forming a conductor paste layer. The conductor paste layer is desirably formed so that the cross section of the resistance 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 fired to remove the resin and the solvent, sinter the metal particles, and bake on the bottom surface of the ceramic substrate 21, The resistance heating element 22 is formed (see FIG. 8B). The temperature of the heating and firing is preferably from 500 to 1000C. If the above-described oxide is added to the conductor paste, the metal particles, the ceramic substrate and the oxide are sintered and integrated, so that the adhesion between the resistance 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 resistance heating element 22 (see FIG. 8C). The metal coating layer 220 can be formed by electrolytic plating, electroless plating, sputtering, or the like, but in consideration of mass productivity, electroless plating is optimal.

(5) Attachment of Terminals and the like Terminals (external terminals 23) for connection to a power supply are attached to the end of the pattern of the resistance heating element 22 by soldering. Further, a thermocouple (not shown) is fixed to the bottomed hole 24 with silver solder, gold solder, or the like, and sealed with a heat-resistant resin such as polyimide. Further, the support pins 38 are fitted and fixed in the concave portions 27, and the manufacture of the ceramic heater 20 is completed (see FIG. 8D).

[0135]

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, 3 and 7) (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 type Using a paste obtained by mixing 11.5 parts by weight of a resin binder, 0.5 parts by weight of a dispersant, and 53 parts by weight of alcohol composed of 1-butanol and ethanol, molding was performed by a doctor blade method to form a 0.47 mm thick sheet. A green sheet 50 was produced.

(2) Next, this green sheet 50
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.
A 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 was printed on a green sheet by screen printing to form a conductor paste layer 120 for a resistance heating element. 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.

The green sheet 50 after the above processing
Further, 37 sheets of green sheets 50 on which the conductor paste was not printed were laminated on the upper side (heating surface) and 13 on the lower side, and pressed at 130 ° C. and a pressure of 8 MPa to form a laminate (FIG. 7). (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 15M.
Hot pressing was performed at Pa for 10 hours to obtain a ceramic plate having a thickness of 4 mm. This was cut into a 310 mm disc to obtain a ceramic plate having a 6 μm thick and 10 mm wide resistance heating element 12 inside.

(5) Next, after polishing the ceramic plate obtained in (4) with a diamond grindstone, a mask is placed, and a blast treatment with SiC particles or the like is performed to achieve a diameter of 3 mm.
Five concave portions 17 having a depth of 2 mm and a depth of 2 mm were formed. Recess 17
As shown in FIG. 1, four were arranged at equal intervals on the circumference of a concentric circle with the ceramic substrate, and one was arranged at the center of the ceramic substrate.

A support pin 18 having the shape shown in FIG. 2 is inserted into each of the five recesses 17, and a stainless steel C-ring 29 is fitted into the recess 17, whereby the support pin 18 is moved. Fixed. This support pin 1
In No. 8, the fixing portion 182 had a diameter of 3 mm, the columnar portion 181 had a diameter of 2 mm, and a length of about 2.1 mm. The support pins 18 protruded from the heating surface 11a by 100 μm.

Further, a bottomed hole 14 for inserting a thermocouple is formed on the bottom surface, and a lifter pin through hole 15 for inserting a lifter pin 16 for carrying a semiconductor wafer or the like is formed. did. (See FIG. 7B)

(6) Next, the portion where the through-hole 13a is formed is cut out to form a blind hole 13b (FIG. 7).
(Refer to FIG. 7 (c)), and using a gold solder made of Ni-Au in the blind hole 13b, an external terminal 13 made of Kovar was connected by heating and reflowing at 700 ° C. (refer to FIG. 7 (d)). Also,
A thermocouple (not shown) for temperature control was inserted into the bottomed hole 14 and sealed with polyimide.

(7) Next, the ceramic heater 10 obtained by the above-described process is fitted into a heat insulating ring of a support container (not shown), and then the ceramic substrate 11 is fixed to the heat insulating ring by using bolts, fixtures and the like. The hot plate unit was obtained by fixing and drawing out the conductive wire and the lead wire from the bottom surface of the heat shielding member of the support container.

Example 2 Production of Ceramic Heater (See FIGS. 4, 5 and 8) (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 placed in a mold and formed into a flat plate to obtain a formed product (green).

(3) Next, the 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 4 mm. Next, a disk having a diameter of 300 mm was cut out from the plate to obtain a ceramic plate (ceramic substrate 21). Drilling was performed on the ceramic substrate 21 to form a through hole 25 for inserting a lifter pin 26 of a silicon wafer and a bottomed hole 24 for embedding a thermocouple.

Further, a mask is placed on the upper side (heating surface) of the ceramic substrate 21, and blast treatment with SiC particles or the like is performed to form a recess 27 having a diameter of 2 mm and a depth of 2.5 mm.
Individual pieces were formed (see FIG. 8A). The arrangement of the recesses 27 is such that four are provided at equal intervals on the circumference of the concentric circle of the ceramic substrate 21 on the relatively outer side, and four are provided at equal intervals on the inner circumference of the concentric circle. In this configuration, one recess 27 is provided at the center of the ceramic substrate.

Then, in each of these concave portions 27,
A support pin 38 made of alumina having the shape shown in FIG. 5 was inserted and fixed so that the tip end protruded from the heating surface 11 a of the ceramic substrate 11. Specifically, the support pin 38 is
After putting a little in 7, using a mallet and tapping lightly,
Fitted in the recess. This support pin 38 has a diameter of 2 m.
m, and the length was about 2.6 mm. This support pin 38
Protruded 100 μm from the heating surface 31a.

(4) Ceramic substrate 2 obtained in (3) above
1, a conductor paste layer was formed by screen printing.
The printing pattern was the pattern shown in FIG. As the conductor paste, Ag 48% by weight, Pt 21% by weight,
SiO ₂ 1.0% by weight, B ₂ O ₃ 1.2% by weight, ZnO
4.1 wt%, PbO 3.4 wt%, ethyl acetate 3.4
% Of butyl carbitol and 17.9% by weight of butyl carbitol.

This conductor paste was an Ag-Pt paste, and the silver particles had an average particle size of 4.5 μm and were scaly. The Pt particles have an average particle size of 0.5
μm was spherical.

(5) Further, after forming the conductor 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 the resistance heating element 22 (see FIG. 8B). The resistance heating element 22 has a thickness of 5 μm.
m, the width was 2.4 mm, and the sheet resistivity was 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. 8 (c)).

(7) Next, a silver-lead solder paste (manufactured by Tanaka Kikinzoku Co., Ltd.) is printed by screen printing on the portion to which the external terminal 23 for securing the connection with the power supply is attached, and a solder layer (not shown) is formed. 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. 8 (d))

(8) A thermocouple (not shown) for controlling the temperature was inserted into the bottomed hole 24 and sealed with polyimide. Thus, the manufacture of the ceramic heater 20 of the present invention has been completed. (9) Next, the ceramic heater 20 obtained by the above process is fitted into a heat insulating ring of a supporting container (not shown), and then the ceramic substrate 11 is fixed to the ceramic substrate 11 by using bolts, fixtures and the like.
Was fixed to a heat insulating ring, and the conductive wire and the lead wire were pulled out from the bottom surface of the heat shielding member of the support container, to obtain a hot plate unit.

Comparative Example 1 Production of Ceramic Heater A ceramic heater was produced in the same manner as in Example 1 except for the following steps. That is, in the step (5), instead of providing the concave portion, as shown in FIG. 9, the ceramic substrate 31 is provided with a through hole 37 in which holes of different diameters communicate with each other. The support pin 48 having the cross-sectional shape shown was fixed using the metal fitting 39.

A silicon wafer was placed on the ceramic heaters according to Examples 1 and 2 and Comparative Example 1, and the temperature was raised to 300 ° C. by energizing, and evaluated by the following method.

[0159]Evaluation method  (1) Flatness Using a laser displacement meter, measure the flatness of the ceramic substrate.
Was. This flatness is defined as one point being 0 (base point) and other arbitrary points.
Check how much of the 7 points are displaced from the base point, and
Is the average of The results are shown in Table 1.

(2) In-plane temperature uniformity at steady state A silicon wafer was placed on the ceramic heaters according to the examples and comparative examples, and was supported via support pins. After the temperature was raised to 300 ° C., the silicon wafer was thermo-viewed. The maximum temperature and the minimum temperature were measured, and the temperature difference was calculated. Table 1 shows the results.

[0161]

[Table 1]

As shown in Table 1, all of the ceramic heaters according to the examples had good flatness, and the in-plane temperature distribution of the silicon wafer in a steady state was small. This is because, in the ceramic heater according to the embodiment, what is formed on the surface of the ceramic substrate to fix the support pins is as follows.
It is considered that the strength of the ceramic substrate did not decrease because the recess was formed instead of the through hole. As a result, the ceramic substrate did not warp and the flatness was good. That is, when the flatness is good, the distance between the silicon wafer and the heating surface becomes constant, so that the temperature distribution hardly occurs.

On the other hand, in the comparative example, the flatness was not so good, and the temperature distribution was large due to this.
It is considered that this is because the strength of the ceramic substrate is reduced due to the provision of the through-hole in the ceramic substrate, and the ceramic substrate is warped, thereby reducing the flatness. That is, when the flatness decreases, the distance between the silicon wafer and the heating surface of the ceramic substrate is not constant, and the in-plane temperature distribution increases.

[0164]

As described above, according to the ceramic heaters according to the first and second aspects of the present invention, the through holes formed on the surface of the ceramic substrate for fixing the support pins are provided. Since it is not a concave part, the strength of the ceramic substrate does not decrease, and
The flatness is improved. As a result, the distance between the semiconductor wafer and the heating surface of the ceramic substrate is kept substantially constant, and the entire semiconductor wafer can be heated at a uniform temperature. Also,
In the present invention, since the semiconductor wafer is supported via the support pins, impurities do not transfer from the surface of the ceramic substrate to the semiconductor wafer, and the semiconductor wafer is not contaminated. Further, since the support pins are fixed in the recesses,
Unlike the case where the support pins are fixed to the through holes, the support pins do not fall off due to an accident or the like.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a ceramic heater of the first invention.

2 (a) is a partially enlarged cross-sectional view of the ceramic heater shown in FIG. 1, and FIG. 2 (b) inserts and fixes a support pin to the first ceramic heater of the present invention via a C-ring. It is a perspective view showing a situation.

FIGS. 3A and 3B are front views schematically showing a support pin of the first invention.

FIG. 4 is a bottom view schematically showing an example of the ceramic heater of the second invention.

5A is a partially enlarged cross-sectional view of the ceramic heater shown in FIG. 4, and FIG. 5B is a perspective view schematically showing a state where a support pin provided on the ceramic heater of the present invention is fixed. is there.

FIG. 6 is a front view schematically showing a support pin of the second invention.

FIGS. 7A to 7D are cross-sectional views schematically showing a part of a manufacturing process of the ceramic heater shown in FIG.

FIGS. 8A to 8D are cross-sectional views schematically showing a part of a manufacturing process of the ceramic heater shown in FIG.

FIG. 9A is a partially enlarged cross-sectional view schematically showing a ceramic heater in which a support pin is inserted and fixed in a through hole formed in a ceramic substrate, and FIG. FIG. 3 is a perspective view of a metal fitting used in the embodiment.

[Explanation of symbols]

 10, 20, 30 Ceramic heater 11, 21, 31 Ceramic substrate 11a, 21a, 31a Heating surface 11b, 21b, 31b Bottom surface 12, 22a to 22o Resistance heating element 14, 24 Bottomed hole 130 Conductive paste layer 13, 23 External terminal 13a through hole 13b blind hole 14, 24 bottomed hole 15, 25 through hole for lifter pin 16 lifter pin 17, 27 recessed portion 18, 28, 38, 48 support pin 181, 281 columnar portion 182, 282 fixing portion 19 semiconductor wafer 220 Metal coating layer 29 C-ring 37 Through hole 39 Metal fitting 50 Green sheet

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) KA04

Claims (2)

[Claims] 1. A ceramic heater having a heating element formed on a surface or inside of a ceramic substrate, wherein a concave portion is provided on a heating surface of the ceramic substrate, and a support pin is inserted into the concave portion via a C-ring. A ceramic heater characterized by being fixed. 2. A ceramic heater having a heating element formed on the surface or inside of a ceramic substrate, wherein a concave portion is provided on a heating surface of the ceramic substrate, and a support pin is fitted and fixed in the concave portion. A ceramic heater, characterized in that: