JP2002231420A - Ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater capable of uniformizing a temperature of a heating surface of a silicon wafer, and capable of preventing damage of the silicon wafer. SOLUTION: In this ceramic heater, a resistance heating element composed of two or more circuits is formed on a surface or the inside of a disk-shaped ceramic substrate having a diameter of 200 mm or more. At least one circuit of the resistance heating element is divided in the circumferential direction, and includes a concentric circle or spiral pattern. The total number of circuits of the resistance heating element is 3 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Detailed description of the invention]

[0002]

2. Description of the Related Art Semiconductor products are manufactured through a process of forming a photosensitive resin on a semiconductor wafer as an etching resist and etching the semiconductor wafer. This photosensitive resin is a liquid and is applied to the surface of the semiconductor wafer using a spin coater or the like.However, it must be dried after application, and the applied semiconductor wafer is placed on a heater and heated. become. Conventionally, as a metal heater used for such an application, a heater in which a resistance heating element is arranged on the back surface of an aluminum plate has been adopted.

[0003] However, such a metal heater has the following problems.
There were the following problems. First, because it is made of metal,
The thickness of the ceramic substrate must be as thick as about 15 mm. This is because, in a thin metal plate, warping or distortion occurs due to thermal expansion caused by heating, and the semiconductor wafer mounted on the metal plate is damaged or tilted. However, when the thickness of the ceramic substrate is increased, the weight of the heater increases and the heater becomes bulky.

[0004] The heating temperature is controlled by changing the voltage or the amount of current applied to the resistance heating element.
Since the metal plate is thick, the temperature of the ceramic substrate does not quickly follow changes in voltage and current amount, and it is difficult to control the temperature.

Therefore, as proposed in Japanese Patent Publication No. 8-8247 and Japanese Patent Application Laid-Open No. 11-40330, a temperature near a heating element is measured by using a nitride ceramic having a heating element. Meanwhile, techniques for controlling the temperature have been proposed.

[0006]

However, when a semiconductor wafer is to be heated by using such a technique, a temperature difference occurs on a surface of the ceramic heater to be heated (hereinafter referred to as a heating surface), and the semiconductor wafer is heated. The temperature difference between the semiconductor wafers is increased, the degree of curing of the resin cured product on the semiconductor wafer becomes uneven, and the semiconductor wafer is damaged by thermal shock caused by the temperature difference on the heater surface. .
Further, in order to increase the accuracy of temperature control, even when a temperature near each of the resistance heating elements composed of a plurality of circuits is measured and a different current is applied to each resistance heating element,
Again, a temperature difference sometimes occurred on the heated surface.

The inventors of the present invention have conducted intensive studies on the causes of such a temperature distribution on the heated surface, and as a result,
Despite the temperature control, such a problem occurs because a resistance heating element composed of an appropriate number of circuits corresponding to the size (diameter) of the substrate is not formed on the ceramic substrate. It was found that it was. Also,
Outer peripheral portion of ceramic substrate (1 radius of ceramic substrate)
/ 2), the fact that the temperature is likely to be non-uniform due to heat radiation from the outer edge of the ceramic substrate, and particularly in the process of increasing the temperature (transient characteristics), the fact that the tendency is noticeable appears. Was. In addition, the present inventors have newly found that such a problem is likely to occur when a ceramic substrate having a high thermal conductivity such as a nitride ceramic or a carbide ceramic is used, since the temperature tends to be non-uniform.

[0008]

The inventors of the present invention have further studied and found that a ceramic heater in which a resistance heating element composed of two or more circuits is formed on the surface or inside of a ceramic substrate. When trying to configure a uniform temperature, the resistance heating element should be a circuit divided in the circumferential direction, a circuit of concentric circles or a spiral pattern,
By finding that the total number of circuits is three or more, it has been found that the temperature difference on the heated surface of the object to be heated such as a semiconductor wafer can be reduced, and the first invention has been completed.

Further, the present inventors have found that a certain relationship is established between the diameter of the ceramic substrate and an appropriate total number of circuits of resistance heating elements provided on the ceramic substrate, and have completed the second present invention. It led to.

That is, a ceramic heater according to a first aspect of the present invention is a ceramic heater in which a resistance heating element composed of two or more circuits is formed on the surface or inside of a disk-shaped ceramic substrate having a diameter of 200 mm or more. At least one circuit of the resistance heating element is circumferentially divided and includes a concentric circle or a spiral pattern, and the total number of circuits of the resistance heating element is three or more. It is a heater.

A ceramic heater according to a second aspect of the present invention is a ceramic heater in which a resistance heating element composed of two or more circuits is formed on the surface or inside of a disk-shaped ceramic substrate. At least one of the circuits is divided in a circumferential direction and includes a concentric circle or a spiral pattern. Further, the number of circuits of the resistance heating element and the diameter r (mm) of the ceramic substrate are different from each other. The ceramic heater is characterized in that the following equation (1) is satisfied. n ≧ r ^1.94 × 10 ^-4 (1)

Further, the ceramic heater may be 100 to
Preferably, it is used at 800 ° C.

The ceramic heater includes a temperature measuring element for measuring the temperature of the ceramic substrate, a control section for supplying power to the resistance heating element comprising the plurality of circuits, and a temperature measuring element for measuring the temperature of the ceramic substrate. A storage unit for storing temperature data, and a calculation unit for calculating power required for the resistance heating element from the temperature data are provided, and different powers are supplied to a plurality of circuits of the resistance heating element, respectively. It is desirable to be constituted so that.

Further, the ceramic substrate is preferably made of a nitride ceramic or a carbide ceramic.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ceramic heater of the first invention and the ceramic heater of the second invention described above are the same except for the diameter of the ceramic substrate and the total number of circuits of the resistance heating element. Therefore, different points and different effects of the two inventions will be described first, and thereafter, the ceramic heater of the first invention and the ceramic heater of the second invention will be collectively described as the ceramic heater of the invention. I do.

The ceramic heater according to the first aspect of the present invention is a ceramic heater in which a resistance heating element composed of two or more circuits is formed on the surface or inside of a disk-shaped ceramic substrate having a diameter of 200 mm or more. At least one circuit of the body is circumferentially divided and includes a concentric or spiral pattern, and the total number of circuits of the resistance heating element is three or more.

In the first ceramic heater of the present invention, the diameter of the ceramic substrate is 200 mm or more, and the total number of circuits of the resistance heating elements formed on the ceramic substrate is 3 or more. For a ceramic substrate with a diameter of 200 mm or more,
As described above, since the temperature of the heating surface is likely to be uneven, singular points such as hot spots and cooling spots may be locally generated. This is because the total number of circuits needs to be 3 or more. For the same reason, when the diameter is 300 mm or more, it is desirable that the total number of circuits of the resistance heating element be 7 or more. Further, it is desirable that the total number of circuits of the resistance heating element is set to 20 as an upper limit. If the total number exceeds 20, it interferes with each other and makes temperature control difficult.

The ceramic heater according to the present invention is a ceramic heater in which a resistance heating element comprising two or more circuits is formed on the surface or inside of a disk-shaped ceramic substrate,
At least one circuit of the resistance heating element is divided in the circumferential direction and includes concentric circles. Further, the total number n of circuits of the resistance heating element and the diameter r (m) of the ceramic substrate
m) is characterized by the following equation (1). n ≧ r ^1.94 × 10 ^-4 (1)

In the ceramic heater according to the second aspect of the present invention, the total number n of circuits of the resistance heating element and the diameter r (m) of the ceramic substrate
m), the total number of circuits of the resistance heating element with respect to the area of the heating surface of the ceramic substrate becomes sufficiently large, and the area to be heated by one circuit becomes an appropriate range. Variations in the amount of generated heat in the circuit can be reduced, and fine control of the amount of generated heat can be easily and accurately performed. As a result, for example, it is possible to prevent a low-temperature region such as a cooling spot from being generated at a boundary portion of the circuit, and it is possible to make the temperature of the heating surface of the ceramic heater uniform. Therefore, the object to be heated can be heated uniformly, and for example, the degree of cure of the cured resin on the semiconductor wafer can be made uniform, and the semiconductor wafer can be prevented from being damaged.

In the ceramic heater according to the second aspect of the present invention, the above equation (1) showing the relationship between the diameter of the ceramic substrate and the total number of circuits of the resistance heating element will be described with reference to an example. Consider a ceramic heater in which a resistance heating element whose total number of circuits is 6 is formed on a disk-shaped ceramic substrate. First, the diameter of the ceramic substrate is 210 (m
In the case of m), when this diameter is substituted into the above equation (1), n
≧ 3.2. That is, the total number of circuits only needs to be four or more, and this ceramic heater satisfies the relationship of the above equation (1). On the other hand, if the diameter of the ceramic substrate 11 is 3
In the case of 00 (mm), when this diameter is substituted into the above equation (1), n ≧ 6.4. That is, it is understood that the total number of circuits is required to be 7 or more, and this ceramic heater does not satisfy the relationship of the above equation (1) and needs to be divided into smaller circuits.

That is, in order to satisfy the relationship of the above equation (1), it is necessary to increase the total number of circuits of the resistance heating element as the diameter of the ceramic substrate increases, and the diameter of the ceramic substrate is 200 (mm) or more. The ceramic heater requires three or more circuits, and the ceramic heater having a ceramic substrate diameter of 210 (mm) requires four or more circuits, and the ceramic substrate has a diameter of 300 (m).
In the case of the ceramic heater m), seven or more circuits are required.

The ceramic heater of the present invention has a resistance heating element divided into two or more circuits in the circumferential direction.
The reason for this configuration is that, for example, it is difficult to control the temperature of the heating surface in a circuit composed only of concentric circles. In this way, by dividing the resistance heating element into two or more circuits in the circumferential direction and performing control, it is possible to eliminate non-uniformity of the temperature distribution on the same circumference and heat the object to be heated. The temperature of the surface (heating surface) can be made uniform. In particular, since the temperature is likely to be uneven near the outer periphery due to heat radiation, it is desirable that the circuit at the outer periphery is divided into two or more circuits in the circumferential direction. In this case, the resistance heating element divided into two or more circuits in the circumferential direction does not need to be present in the entire outer peripheral portion,
It only has to exist in the region of the outer peripheral portion. Further, it is more preferable that the resistance heating element divided in the circumferential direction of the outer peripheral portion has an outermost peripheral pattern. This is because the temperature of the outermost portion is most likely to be non-uniform, and it is necessary to control the temperature of this portion. However, this does not deny the formation of the resistance heating element further on the outer circumference of the resistance heating element formed in the outer peripheral portion and divided in the circumferential direction. Furthermore, the resistance heating element divided into two or more circuits in the circumferential direction may exist not only in the outer peripheral part but also in the inner part.

However, like the ceramic heater in JP-A-8-125001, the resistance heating elements 92a to 92a
92k is continuous between the inner part and the outer part, and
In the case of a circuit divided in the circumferential direction (see FIG. 10)
Is not included in the ceramic heater of the present invention. This is because in the ceramic heater having such a configuration, the temperature becomes uneven in the diameter direction of the inner portion of the ceramic substrate, and the ceramic substrate is likely to be warped.

The warpage of the ceramic substrate is 60 μm.
It is desirable that: If the warpage exceeds 60 μm, the variation in distance between the semiconductor wafer to be heated and the ceramic substrate becomes large, so that the semiconductor wafer cannot be heated uniformly.

As a method of heating a semiconductor wafer, the semiconductor wafer is directly mounted on a ceramic substrate,
There are two types of methods: a heating method and a heating method in which the semiconductor wafer and the ceramic substrate are separated by 5 to 5000 μm. In any case, the warpage of the ceramic substrate is preferably 60 μm or less.

The ceramic heater of the present invention has a concentric or spiral-shaped resistance heating element. By forming the resistance heating element in such a pattern, it is possible to eliminate unevenness in temperature in the diameter direction of the ceramic substrate and also prevent warpage of the ceramic substrate. In particular, the inner part (1/1 of the radius of the ceramic substrate)
Since the temperature in the diametric direction is more non-uniform than in the circumferential direction in the portion from the inner portion to the inner portion, the circuit in the inner portion preferably has a concentric or spiral pattern. Note that a resistance heating element divided into two or more circuits in the circumferential direction and a concentric or spiral pattern resistance heating element may be mixed in the inner portion of the ceramic substrate. This is because unevenness in the temperature of the inner portion of the ceramic substrate can be eliminated, and warpage of the ceramic substrate can be prevented.

Therefore, in the ceramic heater of the present invention,
It is desirable to form a resistance heating element divided into two or more circuits in the circumferential direction on the outer peripheral part, and to form a concentric or spiral-shaped resistance heating element on the inner part. When these resistance heating elements work together, the temperature of the heating surface of the ceramic substrate becomes uniform, the warpage does not occur in the ceramic substrate, the distance between the ceramic substrate and the semiconductor wafer becomes constant, and the semiconductor wafer Can be uniformly heated. Further, in the ceramic heater according to the present invention, in particular, it is possible to eliminate the non-uniformity of the temperature on the heating surface of the ceramic substrate which occurs in the process of increasing the temperature (transient characteristics).

1 and 9 are bottom views schematically showing one example of the ceramic heater of the present invention, and FIG. 2 is a partially enlarged sectional view showing a part thereof.

In this ceramic heater 10, a resistance heating element 12 is formed on a bottom surface 11b opposite to a heating surface 11a of a ceramic substrate 11 formed in a disk shape. The resistance heating elements 12 are arranged on the outermost periphery of the ceramic substrate 11 in the form of arc patterns repeatedly formed so as to draw a part of a concentric circle. The resistance heating elements 12a to 12d are partially cut inside. The resistive heating elements 12e to 12h having a concentric pattern are arranged.

The outermost resistance heating element 12a is formed by repeating a circular arc-shaped pattern obtained by dividing a concentric circle into four in the circumferential direction, and ends of adjacent arcs are connected by a bent line to form a series of circuits. ing. Then, four circuits of the resistance heating elements 12a to 12d having the same pattern are formed close to each other so as to surround the outer periphery, and constitute an overall annular pattern.

The ends of the resistance heating elements 12a to 12d are formed inside an annular pattern in order to prevent the occurrence of a cooling spot or the like. It is extended toward.

Resistance heating elements 12a-1 formed on the outermost periphery
Inside the 2d, there are formed resistance heating elements 12e to 12h each formed of a circuit of a concentric pattern whose part is cut off. In the resistance heating elements 12e to 12h, a series of circuits is formed by connecting the ends of adjacent concentric circles sequentially with resistance heating elements formed of straight lines.

The resistance heating elements 12a to 12d, 12
e, between 12f, 12g, 12h, belt-like (annular)
Heating element non-forming area is provided, and also in the center part,
A circular heating element non-formation area is provided. Therefore, as a whole, an annular resistance heating element forming area and a heating element non-forming area are alternately formed from the outside to the inside,
By appropriately setting these areas in consideration of the size (diameter) and thickness of the ceramic substrate, the temperature of the heating surface can be made uniform.

The resistance heating elements 12 (12a to 12h)
An external terminal 33 serving as an input / output terminal is connected to both ends thereof via a metal coating layer 120. Further, a through hole 15 for inserting a lifter pin 36 supporting a semiconductor wafer 39 is formed in a portion near the center.
Bottom hole 1 for inserting thermocouple 17 as a temperature measuring element
4 are formed.

The diameter of the ceramic substrate 11 is 210 (m
m), as described above, the total number of circuits needs to be 4 or more. In this ceramic heater 10, the resistance heating elements are composed of eight circuits of the resistance heating elements 12a to 12h. In this case, the above equation (1) is satisfied, the amount of heat generated by the resistance heating element can be controlled with high accuracy, and the temperature of the heating surface can be made uniform.

FIG. 4 is a bottom view schematically showing another example of the ceramic heater of the present invention, and FIG. 5 is a partially enlarged sectional view showing a part thereof. This ceramic heater 50
In the figure, a resistance heating element 52 (52a to 52h) is formed inside a ceramic substrate 51 formed in a disk shape.

That is, on the outermost periphery of the ceramic heater 50, resistance heating elements 52a to 52d each having a repetitive pattern of bent lines divided into four are arranged, and inside the resistance heating elements 52e to 52h each having a circuit of a concentric pattern.
Are arranged at regular intervals.

Further, similarly to the ceramic heater shown in FIG. 1, a plurality of through holes 55 are formed, and a plurality of bottomed holes 54 are formed. Immediately below the ends of the resistance heating elements 52a to 52h. , A through hole 58 is formed.
The blind hole 59 exposing the through hole 58 is formed on the bottom surface 51.
b, the external terminal 53 is inserted into the blind hole 59,
They are joined by a brazing material (not shown).

The diameter of the ceramic substrate 51 is 210 (m).
m), the total number of circuits is required to be 4 or more. In this ceramic heater 50, the resistance heating elements are composed of eight circuits of resistance heating elements 52a to 52h. The formula is established, the amount of heat generated by the resistance heating element can be controlled accurately, and the temperature of the heating surface can be made uniform.

The total number of circuits of the resistance heating element formed in the ceramic heater of the present invention is, as described above, a ceramic heater having a ceramic substrate having a diameter of 210 (mm).
4 or more, and the diameter of the ceramic substrate is 300 (mm)
In the ceramic heater described above, the number is 7 or more, but the upper limit is not particularly limited. However, from the viewpoint of avoiding the complexity of the manufacturing process, reducing the manufacturing cost, and controlling the resistance heating element as easily as possible, the total number of circuits of the resistance heating element is 210 mm in diameter of the ceramic substrate. In this case, it is desirable that the number be 10 or less. When the diameter of the ceramic substrate is 300 (mm), the diameter is preferably 20 or less.

The pattern of the resistive heating element is not particularly limited. For example, the pattern shown in FIG. 1 is a combination of a circular arc repetition pattern and a concentric pattern, and FIG.
And the like, in which resistance heating elements 52a to 52d, which are repetitive patterns of bent lines, are formed on the outermost periphery, and resistance heating elements 52e to 52h, which are concentric patterns, are formed therein. Also, for example, a spiral pattern, an eccentric pattern, a repeating pattern of a bent line, and the like can be used. These may be used in combination, and these may be used in combination with the pattern shown in FIG. 1 or FIG. You may.

Among them, the finer control of the heat generation can be performed in the outer peripheral portion of the ceramic substrate, which has a large heat radiation, and therefore, the pattern shown in FIG. As shown in FIG. 4, a resistive heating element including at least two or more circuits in the circumferential direction is arranged on the outermost periphery of the ceramic substrate, like the pattern in which the repetitive pattern of the bent lines and the concentric pattern are used together. In addition, a pattern in which a resistance heating element composed of another circuit is formed inside the resistance heating element disposed on the outermost periphery is desirable.

The pattern divided in the circumferential direction means that a plurality of line segments are drawn from the center of the ceramic substrate to the outer periphery.
This is a pattern formed in a region divided by the line segment. Usually, it is desirable that all the areas have the same size. The number of divisions is not limited to four as shown in FIG. 1, but may be three or five as long as it is two or more.
Usually, as the size of the ceramic substrate increases,
It is desirable to increase the number of divisions.

1 and 4, the resistance heating element 1
2a to 12d and 52a to 52d are resistance heating elements arranged at the outermost periphery.
It is desirable that the area be formed in a region 90% or more from the center to the distance from the outer periphery to the center. If it is less than 90%, the area of the resistance heating element formed on the outermost periphery becomes too large, so that it becomes difficult to control the temperature of the heating surface.

In FIG. 9, a resistance heating element 12i, 1
2j are formed. In this case, the ceramic substrate 81
The uneven temperature in the circumferential direction in the inner part of the rim can be eliminated. The ceramic heater of the present invention has a
Preferably, it is used at 800 ° C.

It is desirable that the difference between the number of circuits of the resistive heating element formed on the outermost periphery and the number of circuits of the resistive heating element formed therein is within ± 1. If the number of circuits on the outermost periphery is extremely large, the number of circuits in the inside will be small, and it will be difficult to accurately control the amount of heat generation inside the ceramic substrate. This is because accurate temperature control cannot be performed.

In the present invention, the resistance heating element may be formed on the surface (bottom surface) of the ceramic substrate, or the resistance heating element may be embedded inside the ceramic substrate. When the resistance heating element is formed on the surface of the ceramic substrate 11, a conductive paste containing metal particles is applied to the surface of the ceramic substrate 11 to form a conductive 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 on the surface of the ceramic substrate 11, the thickness of the resistance heating element should be 1 to 30.
μm is preferable, and 1 to 10 μm is more preferable. Also,
When a resistance heating element is formed inside the ceramic substrate 11, the thickness is preferably 1 to 50 μm.

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

The resistance value of the resistance 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 resistance heating element is formed inside the ceramic substrate 11, both the thickness and the width are larger. However, when the resistance heating element is provided inside, the distance between the heating surface and the resistance heating element becomes shorter, and Since the temperature uniformity is reduced, it is necessary to increase the width of the resistance heating element itself, and there is no need to consider the adhesion with nitride ceramics etc. Since high melting point metals such as molybdenum and carbides such as tungsten and molybdenum can be used, and the resistance value can be increased, 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 as it propagates, and heats the object to be heated (semiconductor wafer). 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.

The resistance heating element may be rectangular or elliptical in 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 and the aspect ratio is smaller than the above range, the ceramic substrate 11
The amount of heat that propagates in the direction of the heating surface decreases, and a heat distribution similar to the pattern of the resistance heating element is generated on the heating surface. Conversely, if the aspect ratio is too large, the portion directly above the center of the resistance heating element The temperature becomes high, and eventually, a heat distribution approximate to the pattern of the resistance 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 resistance heating element is formed on the surface of the ceramic substrate 11, the aspect ratio is 10 to 200. When the resistance heating element is formed inside the ceramic substrate 11, the aspect ratio is 200 to 5000. desirable.

Although the resistance heating element has a larger aspect ratio when formed inside the ceramic substrate 11,
This is because if the resistance heating element is provided inside, the distance between the heating surface and the resistance heating element is shortened, and the temperature uniformity of the surface is reduced. Therefore, it is necessary to flatten the resistance heating element itself.

The resistance heating element of the present invention is
Is formed at a position close to the bottom surface 11b of the ceramic substrate 11 facing the heating surface 11a, and the distance from the heating surface 11a to the bottom surface 11b is 5%.
It is desirable that the position be more than 0% and up to 99%.
If it is less than 50%, the temperature distribution is generated because it is too close to the heating surface. Conversely, if it exceeds 99%, the ceramic substrate 11 itself is warped and the semiconductor wafer is damaged. .

When the resistance heating element is formed inside the ceramic substrate 11, 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.

The conductive paste is not particularly limited, but preferably contains not only metal particles or conductive ceramic for ensuring conductivity, but also resin, solvent, 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 the metal particles and sintering the metal particles and the metal oxide as the 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 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 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.

The area resistivity when the resistance heating element is formed is preferably from 0.1 mΩ to 10 Ω / □. When the area resistivity is less than 0.1 mΩ / □, the width of the resistive heating element pattern must be very thin, about 0.1 to 1 mm, in order to secure a heat generation amount. If the wire breaks due to chipping or the like, the resistance value fluctuates, and if the sheet resistivity exceeds 10Ω / □, the heating value cannot be secured unless the width of the resistive heating element pattern is increased. This is because the degree of freedom in design is reduced, and it becomes difficult to make the temperature of the heating surface uniform.

When the resistance heating element is formed on the surface of the ceramic substrate 11, it is desirable that a metal coating layer (see FIG. 2) 120 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 120 to be formed is preferably 0.1 to 10 μm.

The metal used for forming the metal coating layer 120 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 12 requires a terminal for connection to a power supply. This terminal is attached to the resistance heating element 12 via solder. However, nickel prevents heat diffusion of the solder. is there. An example of the connection terminal is an external terminal 33 made of Kovar.

When the resistance heating element is formed inside the ceramic substrate 11, no coating is required 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, 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.

The ceramic heater according to the present invention has a temperature measuring element for measuring the temperature of the ceramic substrate, a control section for supplying power to the resistance heating element comprising the plurality of circuits, and a temperature measuring element for measuring the temperature. A storage unit for storing temperature data; and a calculation unit for calculating power required for the resistance heating element from the temperature data, wherein different power is supplied to a plurality of circuits of the resistance heating element, respectively. It is desirable to be configured. Since the calculation unit is provided, even if there is a sudden temperature change (disturbance), the power required for each circuit of the heating element can be accurately calculated based on the temperature measurement result. Because it can be.

FIG. 3 is a block diagram schematically showing a ceramic heater 40 as an example of the present invention. In the ceramic heater 40, the ceramic substrate 41 is formed in a disk shape, and a resistance heating element 42 is formed on a bottom surface 41 b of the ceramic substrate 41.

In order to heat the heating surface 41a of the ceramic substrate 41 so that the entire temperature thereof becomes uniform, an arc formed by concentric circles divided in the circumferential direction is formed on the outermost periphery of the bottom surface 41b of the ceramic substrate 41. Is provided so as to surround the outer periphery, and a concentric pattern of resistance heating elements 42b is formed inside the resistance heating elements 42a.

The diameter of the ceramic substrate 41 is 210 (m
m), the number n of circuits is 4 as described above.
The ceramic heater 40 has a pattern similar to that of the ceramic heater shown in FIG. 1, and the total number of circuits is eight, which satisfies the relationship of the expression (1).

The resistance heating elements 42 (42a, 42b)
An external terminal 43 serving as an input / output terminal is connected to both ends thereof via a metal coating layer 420. A socket 20 is attached to the external terminal 43, and the socket 20 is connected to a control unit having a power supply. Also,
A through hole 45 for inserting a lifter pin 36 supporting the semiconductor wafer 39 is formed in a portion near the center,
Further, a bottomed hole 44 for inserting a thermocouple 47 as a temperature measuring element is formed.

The ceramic substrate 41 has a bottom surface 41.
A bottomed hole 44 is provided from the b side, and a thermocouple 47 as a temperature measuring element is fixed to the bottom of the bottomed hole 44. This thermocouple 47 is connected to the storage unit 21 and each thermocouple 47
Can be measured at regular intervals, and the data can be stored. And this storage unit 21
Is connected to the control unit 23 and is connected to the calculation unit 22 to calculate a voltage value and the like controlled by the calculation unit 22 based on the data stored in the storage unit 21. Based on this, the control unit 23 Thus, a predetermined voltage is applied to each resistance heating element 42 so that the temperature of the heating surface 41a can be made uniform.

Next, the operation of the ceramic heater 40 will be described. First, when power is supplied to the ceramic heater 40 by operating the control unit 23,
Although the temperature of the ceramic substrate 41 itself starts to rise, the surface temperature of the outer peripheral portion becomes slightly low.

The data measured by the thermocouple 47 is stored in the storage unit 2
1 is stored once. Next, this temperature data is calculated by the arithmetic unit 2
2, and the calculation unit 22 calculates a temperature difference ΔT at each measurement point, and further calculates data ΔW necessary for uniforming the temperature of the heating surface 41a.

For example, the resistance heating element 42a and the resistance heating element 4
If there is a temperature difference ΔT in 2b and the resistance heating element 42a is lower, power data ΔW that makes ΔT zero is calculated, transmitted to the control unit 23, and the power based on this is generated by the resistance heating element 42a. It is put into the body 42a to raise the temperature.

Regarding the power calculation algorithm, the simplest method is to calculate the power required for raising the temperature from the specific heat of the ceramic substrate 41 and the weight of the heating area. In addition, a correction coefficient due to the resistance heating element pattern is taken into account. May be. Alternatively, a temperature rise test may be performed on a specific resistance heating element pattern in advance, and a function of the temperature measurement position, the input power, and the temperature may be obtained in advance, and the input power may be calculated from this function. Then, the applied voltage and the time corresponding to the power calculated by the calculation unit 22 are transmitted to the control unit 23, and the control unit 23 supplies power to each resistance heating element 42 based on the values.

As for the temperature control method, it is desirable to use the above method. For example, when the temperature exceeds a predetermined set temperature, the supply of power is stopped for each circuit of the resistance heating element, and the temperature becomes lower than the predetermined set temperature. Then, a control or the like for restarting the supply of power may be used. For the supplied power, a control or the like for keeping the power constant at the time of supply without performing an operation or the like may be used. Further, the temperature control method is not limited to these.

The ceramic forming the ceramic heater 10 of the present invention is preferably a nitride ceramic or a carbide ceramic. Nitride ceramics and carbide ceramics have a smaller coefficient of thermal expansion than metals and have much higher mechanical strength than metals.
Even if the thickness of 1 is reduced, it does not warp or warp due to heating. Therefore, the ceramic substrate 11 can be made thin and light. Further, since the thermal conductivity of the ceramic substrate 11 is high and the ceramic substrate itself is thin, the surface temperature of the ceramic substrate quickly follows the temperature change of the resistance heating element. That is, the resistance heating element 1 is changed by changing the voltage and the current value.
By changing the temperature of 2, the surface temperature of the ceramic substrate can be controlled. In addition, nitride ceramics and carbide ceramics have a high thermal conductivity, so that the temperature variation due to the heating element pattern is likely to occur. Therefore, the configuration of the present invention functions more effectively than oxide ceramics.

As the above 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.

The carbide ceramics include, for example, silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, tungsten carbide and the like. 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 as 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.

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 resistance 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 thickness of the ceramic substrate 11 is 0.5 to 5
mm is preferred. If the thickness is less than 0.5 mm, the strength is reduced and the material is easily damaged. On the other hand, if the thickness is more than 5 mm, heat is difficult to propagate, and the heating efficiency is deteriorated.

The diameter of the ceramic substrate 11 is 20
0 mm or more is desirable. This is because the temperature of the heating surface is more likely to be non-uniform as the ceramic substrate has a larger diameter, and the configuration of the present invention functions effectively. In addition, a substrate having such a large diameter can mount a large-diameter semiconductor wafer. The diameter of the ceramic substrate is
In particular, it is desirable to be 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

In the ceramic heater 10 of the present invention,
The ceramic substrate 11 has a heating surface 1 on which an object to be heated is placed.
1a, a bottomed hole 14 is provided toward the heating surface 11a from the opposite side, and the bottom of the bottomed hole 14 is formed relatively closer to the heating surface 11a than the resistance heating element 12. It is desirable to provide a temperature measuring element such as a pair 17.

It is preferable that the distance between the bottom of the bottomed hole 14 and the heating surface 11a is 0.1 mm to 1/2 of the thickness of the ceramic substrate. Is also close to the heating surface 11a, which enables more accurate measurement of the temperature of the semiconductor wafer.

If the distance between the bottom of the bottomed hole 14 and the heating surface 11a is less than 0.1 mm, heat is radiated, and a temperature distribution is formed on the heating surface 11a. This is because the temperature is easily affected by the body temperature, the temperature cannot be controlled, and a temperature distribution is formed on the heating surface 11a.

The diameter of the bottomed hole 14 is 0.3 mm to 5 mm.
It is desirable that This is because if it is too large, the heat dissipation increases, and if it is too small, the workability decreases and the distance to the heating surface 11a cannot be equalized.

As shown in FIG. 1, it is desirable that a plurality of the bottomed holes 14 are arranged symmetrically with respect to the center of the ceramic substrate 11 so as to 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.

The size of the junction of the thermocouple is preferably equal to 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 14 using gold brazing, silver brazing or the like.
And then sealed with a heat-resistant resin, or both 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.

Next, a method for manufacturing the ceramic heater of the present invention will be described. 6A to 6D are cross-sectional views schematically showing a method for manufacturing a ceramic heater in which a resistance heating element on the bottom surface of a ceramic substrate is formed.

(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 formed into granules by a method such as spray drying, and the granules are put into a mold or the like and pressed to be formed into a plate shape, thereby forming a green body (green). Is prepared. Next, the formed body is heated, fired and sintered to produce a ceramic plate. Thereafter, the ceramic substrate 11 is manufactured by processing it into a predetermined shape.
(A)).

By performing heating and firing while applying pressure, a ceramic substrate 11 having no pores can be manufactured. Heating and firing may be performed at a sintering temperature or higher.
0 to 2500 ° C. In oxide ceramics,
1500 ° C to 2000 ° C.

Next, as necessary, a portion serving as a through hole 15 for inserting a lifter pin for supporting a semiconductor wafer and a bottomed hole for embedding a temperature measuring element such as a thermocouple 17 are formed in the ceramic substrate 11. A portion to be 14 is formed.

(2) Step of Printing Conductive Paste on Ceramic Substrate The conductive paste is a highly viscous fluid composed of metal particles composed of two or more kinds of noble metals, a resin, and a solvent. The following formula (1) is established between the total number n of circuits of the resistance heating element 12 provided on the ceramic substrate 11 and the diameter r (mm) of the ceramic substrate 11 by screen printing or the like of the conductive paste. A conductor paste layer to be a resistance heating element pattern is formed. n ≧ r ^1.94 × 10 ^-4 (1)

At this time, a conductor paste layer is formed on the outermost periphery of the ceramic substrate 11 so as to form at least two or more circuits divided in the circumferential direction, and the inside of the conductor paste layer printed on the outermost periphery is formed. Then, it is desirable to form a conductor paste layer that becomes another circuit. The pattern formed on the outermost periphery of the ceramic substrate as the resistance heating element pattern includes, for example, the repetition pattern of arcs shown in FIG. 1, the repetition pattern of bending lines shown in FIG. 4, and the like. The pattern formed therein may be, for example, a concentric pattern. Further, it is desirable that the conductive paste layer is formed so that the cross section of the resistance heating element 12 after firing is square and flat.

(3) Firing of Conductive Paste The conductive paste layer printed on the bottom surface of the ceramic substrate 11 is heated and fired to remove the resin and the solvent, and sinter the metal particles.
The resistance heating element 12 is formed (FIG. 6B). 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 and the ceramic substrate is improved.

(4) Formation of Metal Coating Layer A metal coating layer 120 is provided on the surface of the resistance heating element 12 (FIG. 6C). The metal coating layer 120 can be formed by electrolytic plating, electroless plating, sputtering, or the like. However, considering mass productivity, electroless plating is optimal.

(5) Attachment of Terminals and the like Terminals (external terminals 33) for connection to a power supply are attached to the end of the pattern of the resistance heating element 12 by soldering. Further, the thermocouple 17 is fixed to the bottomed hole 14 with silver brazing, gold brazing or the like,
After sealing with a heat-resistant resin such as polyimide, the manufacture of the ceramic heater is completed (FIG. 6D). In the ceramic heater of the present invention, an electrostatic chuck may be provided by providing an electrostatic electrode, or a chuck top plate for a wafer prober may be provided by providing a chaptop conductor layer.

[0112]

The present invention will be described in more detail below. (Example 1) Production of a ceramic heater made of aluminum nitride (see FIGS. 1 and 2) (1) Aluminum nitride powder (average particle size: 1.1 μm) 1
A composition comprising 00 parts by weight, 4 parts by weight of yttria (average particle size: 0.4 μm), 12 parts by weight of an acrylic binder and alcohol was spray-dried to prepare a granular powder.

(2) Next, the granular powder was put into a mold and molded into a flat plate to obtain a green body. (3) The processed form is processed at 1800 ° C., pressure: 2
Hot pressing was performed at 0 MPa to obtain an aluminum nitride plate having a thickness of 3 mm. Next, a diameter 310
mm was cut out to obtain a ceramic plate (ceramic substrate) 11.

Drilling is performed on this molded body to form a portion serving as a through hole 15 for inserting a lifter pin for supporting a semiconductor wafer and a portion serving as a bottomed hole 14 for embedding a thermocouple (diameter: 1.1 mm, depth 6 mm) (FIG. 6).
(A)).

(4) The ceramic substrate 11 obtained in the above (3)
Then, a conductor paste was printed by screen printing, and a conductor paste layer was formed such that the total number of circuits of the resistance heating element 12 was eight. This is a value set so that the following equation (1) is established between the total number n of the circuits of the resistance heating elements 12 provided on the ceramic substrate 11 and the diameter r (mm) of the ceramic substrate 11. . n ≧ r ^1.94 × 10 ⁻⁴ (1) Incidentally, in this case, n ≧ 6.8. In addition, as shown in FIG. 1, as the printing pattern, a repetition pattern of circular arcs formed by dividing a concentric circle in the outermost circumference in the circumferential direction and a concentric pattern inside the same are formed.

As the conductive paste, Solvest PS603D manufactured by Tokuri Chemical Laboratory, which is used for forming through holes in a printed wiring board, was used. This conductor paste is a silver-lead paste, and is based on 100 parts by weight of silver.
Containing 7.5 parts by weight of a metal oxide consisting of lead oxide (5% by weight), zinc oxide (55% by weight), silica (10% by weight), boron oxide (25% by weight) and alumina (5% by weight) Met. The silver particles have an average particle size of 4.5 μm.
m, it was scaly.

(5) Next, the ceramic substrate 11 on which the conductive paste is printed is heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and to form the ceramic substrate 11
To form a resistance heating element 12 (FIG. 6).
(B)). The silver-lead resistance heating element 12 has a thickness of 5 μm,
The width was 2.4 mm, and the sheet resistivity was 7.7 mΩ / □.

(6) An electroless nickel plating bath composed of an aqueous solution having a concentration of 80 g / l nickel sulfate, 24 g / l sodium hypophosphite, 12 g / l sodium acetate, 8 g / l boric acid, and 6 g / l ammonium chloride was used. The ceramic substrate 11 prepared in (5) is immersed in the silver-lead resistance heating element 1.
A metal coating layer (nickel layer) having a thickness of 1 μm was deposited on the surface of No. 2 (FIG. 6C).

(7) A silver-lead solder paste (manufactured by Tanaka Kikinzoku Co., Ltd.) was printed by screen printing on a portion where a terminal for securing connection to a power supply was to be formed, thereby forming a solder layer. Next, an external terminal 33 made of Kovar was placed on the solder layer, and heated and reflowed at 420 ° C. to attach the external terminal 33 to the surface of the resistance heating element 12.

(8) A thermocouple for controlling temperature is formed in the bottomed hole 14.
And a ceramic adhesive (Aron Ceramic manufactured by Toa Gosei Co., Ltd.)
Was obtained (FIG. 6 (d)). Further, a control unit having a power supply,
Temperature controller with storage unit and operation unit (Omron Corporation)
E5ZE), the wires from the control unit 23 were connected to the ceramic heater 10 via the external terminals 33, and the wires from the thermocouple 17 were connected to the storage unit 21. Thus, the manufacture of the ceramic heater 10 was completed. .

Example 2 Manufacture of Aluminum Nitride Ceramic Heater (See FIG. 4) When a conductor paste is printed on a ceramic substrate by screen printing, a circle is formed on the outermost periphery as shown in FIG. A ceramic heater in which a resistance heating element is formed on the bottom surface of a ceramic substrate in the same manner as in Example 1 except that a repetitive pattern of bent lines formed by being divided in the circumferential direction and a concentric pattern are formed inside thereof. And the above-mentioned temperature controller was connected. However, the actual repetition pattern of the bending line has a smaller interval than that shown in FIG.
Therefore, the number of repetitions was large and the width was wide. The total number of circuits in the pattern was set to eight. This is a value set so that the relationship of the above equation (1) is established between the total number n of circuits of the resistance heating element 52 provided on the ceramic substrate 51 and the diameter r (mm) of the ceramic substrate 51. Incidentally, also in this case, n ≧ 6.8.

Example 3 Production of a Ceramic Heater Made of Silicon Carbide Average Particle Size 1.1 μm (Dia-Chic by Yakushima Electric Works)
C-1000) silicon carbide and a sintering temperature of 190
0 ° C., and the surface of the obtained ceramic substrate was 1500 ° C.
In the same manner as in Example 1 except that a 1 μm thick SiO ₂ layer was formed on the surface by baking for 2 hours, a ceramic heater made of silicon carbide was manufactured, and the above temperature controller was connected.

Example 4 Production of a Ceramic Heater Made of Aluminum Nitride (See FIG. 8) When a conductor paste is printed on a ceramic substrate by screen printing, a concentric pattern as shown in FIG. Was formed in the same manner as in Example 1 except that a ceramic heater 70 was manufactured, and the above-mentioned temperature controller was connected. The total number of circuits in the pattern was 16. This is because the resistance heating element 7 provided on the ceramic substrate 71
2 and the diameter r (m) of the ceramic substrate 71.
m) is set so that the relationship of the above equation (1) holds. FIG. 8 is a bottom view schematically showing a resistance heating element pattern in the ceramic heater of the present invention. In the ceramic heater 70, resistance heating elements 72 a to 72 h formed of a repetitive pattern of bent lines divided in the circumferential direction are provided on the outermost periphery of the ceramic substrate 71.
Are formed, and on the inner periphery thereof, resistance heating elements 72i to 72l each having a similar repetitive pattern of bent lines are formed. Further, concentric resistance heating elements 72m to 72p are formed on the inner periphery thereof, and the total number of circuits is 16.

(Example 5) Manufacturing of a ceramic heater made of aluminum nitride (see FIG. 9) When a conductor paste was printed on a ceramic substrate by screen printing, as shown in FIG. A ceramic heater was manufactured and the above-mentioned temperature controller was connected in the same manner as in Example 1 except that a pattern divided into two in the circumferential direction was formed in the portion. The total number of circuits in the pattern was 9. This is the total number n of circuits of the resistance heating element 12 provided on the ceramic substrate 11.
It is a value set so that the relationship of the above equation (1) is established between the value and the diameter r (mm) of the ceramic substrate 11.

Comparative Example 1 Production of Aluminum Nitride Ceramic Heater (See FIG. 7) As described in Japanese Patent Application Laid-Open No. H11-40330, the pattern of the resistance heating element was changed to a concentric pattern only (see FIG. 7). 7), a ceramic heater 60 was manufactured in the same manner as in Example 1, and the above-mentioned temperature controller was connected. This is because although the relationship of the above equation (1) holds between the total number n of the circuits of the resistance heating elements provided on the ceramic substrate and the diameter r (mm) of the ceramic substrate, the circuit is divided in the circumferential direction. The pattern has no circuit.

(Comparative Example 2) Manufacture of a ceramic heater made of aluminum nitride Example 1 was repeated except that the number of circuits composed of inner concentric patterns was set to 2 and the total number of circuits was set to 6 for the pattern of the resistance heating element. A ceramic heater was manufactured in the same manner as described above, and the above-mentioned temperature controller was connected. This is a value set so that the relationship of the above equation (1) does not hold between the total number n of the circuits of the resistance heating elements provided on the ceramic substrate and the diameter r (mm) of the ceramic substrate 61.

Comparative Example 3 Manufacture of Ceramic Heater Made of Aluminum Nitride (See FIG. 10) As described in Japanese Patent Application Laid-Open No. 8-125001, the pattern of the resistance heating element was changed between the inner part and the outer part of the ceramic substrate. A ceramic heater was manufactured in the same manner as in Example 1 except that the circuit was a continuous circuit at a portion and was divided in the circumferential direction (see FIG. 10). A thermostat was connected. this is,
The total number n of circuits of the resistance heating element provided on the ceramic substrate
And the diameter r (mm) of the ceramic substrate, the relationship of the above equation (1) is satisfied, but there is no circuit having a concentric or spiral pattern.

Comparative Example 4 Production of a Ceramic Heater Made of Aluminum Nitride A ceramic heater was produced in the same manner as in Example 1, except that the diameter of the ceramic substrate was 200 mm and the total number of circuits was 2. Connected. This is set so that the relationship of the above equation (1) does not hold between the total number n of the circuits of the resistance heating elements provided on the ceramic substrate and the diameter r (mm) of the ceramic substrate. .

(Test Example) The diameter of the ceramic substrate was 150
A ceramic heater was manufactured and the above-mentioned temperature controller was connected in the same manner as in Comparative Example 1 except that mm was used. This is because although the relationship of the above equation (1) holds between the total number n of the circuits of the resistance heating elements provided on the ceramic substrate and the diameter r (mm) of the ceramic substrate, the circuit is divided in the circumferential direction. The pattern has no circuit.

The ceramic heaters according to Examples 1 to 5, Comparative Examples 1 to 4, and Test Examples obtained through the above steps were evaluated by the following indexes. Table 1 shows the results.

[0131]Evaluation method  (1) Temperature distribution in the heating plane at the time of steady state A system with a 17-point temperature measuring element (Pt resistance thermometer)
Using a recon wafer, the in-plane temperature distribution was measured.
The temperature distribution is based on the maximum and minimum temperatures at 200 ° C.
Shown by temperature difference. (2) Transient in-plane temperature distribution Measure the in-plane temperature distribution when the temperature rises from room temperature to 190 ° C.
Specified. The temperature distribution shows the highest and lowest temperatures during heating.
Shown by the maximum value of the temperature difference from the temperature. (3) The amount of warpage of the ceramic substrate
Manufactured). (4) In-plane temperature within 10 mm from the outer periphery of the ceramic substrate
Temperature distribution Silicon wafer with 10 points temperature measuring element
Was used to measure the in-plane temperature distribution of the heated surface. Temperature distribution
Is the difference between the maximum and minimum temperatures at 200 ° C
Show. (5) Temperature distribution of silicon wafer The silicon wafer is separated from the ceramic substrate by 100 μm.
Then, the temperature distribution was measured with a thermoviewer. Temperature distribution
Is the difference between the maximum and minimum temperatures at 200 ° C
Indicated.

[0132]

[Table 1]

As is clear from Table 1, the ceramic heaters according to the examples all had small in-plane temperature distributions in the steady state and the transient state. This is because the ceramic heater according to the embodiment satisfies the following formula (1), which satisfies the following expression (1), which indicates the relationship between the total number n of circuits of the resistance heating elements provided on the ceramic substrate and the diameter r (mm) of the ceramic substrate. Because the body was formed, the total number of circuits of the resistance heating element with respect to the area of the heating surface of the ceramic substrate became sufficiently large, the area to be heated by one circuit became an appropriate range, and the variation in the amount of heat generated within one circuit was reduced. As a result, it is considered that fine control of the calorific value can be performed with high accuracy, and the heating surface becomes uniform. n ≧ r ^1.94 × 10 ^-4 (1)

On the other hand, the ceramic heater according to the comparative example
As compared with the ceramic heater according to the example, the in-plane temperature distribution during the steady state and during the transition was large. This is Comparative Example 2
Is not formed as in the ceramic heater according to the above, the number of circuits of the number of circuits satisfying the above equation (1) is not formed, and the total number of circuits of the resistance heaters with respect to the area of the heating surface is small. Since the heating area was too large, or because the pattern of the resistance heating element was not divided in the circumferential direction as in the ceramic heater according to Comparative Example 1, it was difficult to control the heating area. It is considered that it was difficult to control with high accuracy, and the heating surface could not be made uniform.

The temperature distribution on the heating surface of the ceramic heater according to Comparative Example 1 is the same as the temperature distribution at the outer peripheral portion, that is, is caused by the temperature distribution at the outer peripheral portion. The temperature distribution of the heating surface of the heater is different from the temperature distribution of the outer peripheral portion, that is, not due to the temperature distribution in the outer peripheral portion, but due to a temperature difference between the outer peripheral portion and the inside thereof. This is because the pattern of the resistance heating element formed on the ceramic heater according to Comparative Example 1 is not divided in the circumferential direction, and the area heated by the circuit formed on the outer peripheral portion where temperature distribution is likely to occur is too large. Therefore, it is considered that temperature control in the outer peripheral portion became difficult, and a temperature distribution occurred in the outer peripheral portion. Further, in the ceramic heater according to Comparative Example 3, since the resistance heating element was only the pattern divided in the circumferential direction, the ceramic substrate was likely to be warped greatly and the silicon wafer could not be uniformly heated. Can be In the ceramic heater according to Comparative Example 4, since the total number of circuits was less than 3, local temperature control could not be performed, and it was estimated that the temperature difference was large. Furthermore, the ceramic heaters according to the test examples show that a ceramic heater having a ceramic substrate with a diameter of less than 200 mm has a small temperature distribution even when only a concentric resistive heating element is used. Therefore,
It was considered that the adjustment as in the present invention was necessary for a ceramic heater having a ceramic substrate having a diameter of 200 mm or more.

[0136]

As described above, according to the ceramic heater of the present invention, it is possible to easily and precisely control the amount of generated heat with high accuracy, so that the temperature of the heating surface of the semiconductor wafer can be made uniform. it can. As a result, the degree of cure of the resin cured product on the semiconductor wafer can be made uniform, and damage to the semiconductor wafer can be prevented.

[Brief description of the drawings]

FIG. 1 is a bottom view schematically showing a pattern of a resistance heating element in 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 block diagram schematically showing another example of the ceramic heater of the present invention.

FIG. 4 is a bottom view schematically showing a pattern of a resistance heating element in the ceramic heater of the present invention.

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

FIGS. 6A to 6D are cross-sectional views schematically showing a part of a manufacturing process of a ceramic heater having a resistance heating element formed on a bottom surface according to the present invention.

FIG. 7 is a bottom view schematically showing a pattern of a resistance heating element in the ceramic heater of the present invention.

FIG. 8 is a bottom view schematically showing a pattern of a resistance heating element in the ceramic heater of the present invention.

FIG. 9 is a bottom view schematically showing a pattern of a resistance heating element in the ceramic heater of the present invention.

FIG. 10 is a bottom view schematically showing a pattern of a resistance heating element of a ceramic heater disclosed in JP-A-8-125001.

[Explanation of symbols]

10, 40, 50, 60, 70, 80 Ceramic heaters 11, 41, 51, 61, 71, 81 Ceramic substrate 11a, 41a Heating surface 11b, 41b Bottom surface 12 (12a to 12j), 42 (42a, 42b), 5
2 (52a to 52h) Resistance heating element 120, 420 Metal coating layer 14, 44, 54 Bottomed hole 15, 45, 55 Through hole 17, 47 Thermocouple 20 Socket 21 Storage unit 22 Operation unit 23 Control unit 33, 43 External Terminal 36 Lifter pin 39 Semiconductor wafer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/20 393 H01L 21/30 567 F term (Reference) 3K034 AA02 AA06 AA08 AA10 AA16 AA19 AA21 AA34 AA37 BB06 BB14 BC04 BC12 DA04 DA05 HA10 JA02 JA10 3K058 AA86 BA19 CA12 CA23 CA46 CA52 CA61 CA69 CE12 CE19 CE23 3K092 PP20 QA05 QB08 QB12 QB32 QB43 QB44 QB51 QB74 QB76 QC19 QC52 RF03 RF11 RF17 UA05 UA06 VV22 5046

Claims (5)

[Claims] 1. A ceramic heater having a resistance heating element comprising two or more circuits formed on a surface or inside a disk-shaped ceramic substrate having a diameter of 200 mm or more, wherein at least one circuit of the resistance heating element comprises: A ceramic heater which is divided in a circumferential direction, includes a concentric circle or a spiral pattern, and wherein the total number of circuits of the resistance heating element is three or more. 2. A ceramic heater in which a resistance heating element composed of two or more circuits is formed on the surface or inside of a disk-shaped ceramic substrate, wherein at least one circuit of the resistance heating element is arranged in a circumferential direction. It is divided and includes a concentric circle or a spiral pattern, and further has a total number n of circuits of the resistance heating element and a diameter r (mm) of the ceramic substrate.
And the following formula (1) is satisfied. n ≧ r ^1.94 × 10 ^-4 (1) 3. The ceramic heater according to claim 1, wherein the ceramic heater is 100 to 80.
The ceramic heater according to claim 1, which is used at 0 ° C. 4. A temperature measuring element for measuring a temperature of the ceramic substrate, a control unit for supplying electric power to a resistance heating element comprising the plurality of circuits, and a storage for storing temperature data measured by the temperature measuring element. And a calculation unit for calculating the power required for the resistance heating element from the temperature data, and a plurality of circuits of the resistance heating element are configured to be supplied with different powers, respectively. The ceramic heater according to claim 1. 5. The ceramic heater according to claim 1, wherein said ceramic substrate is made of a nitride ceramic or a carbide ceramic.