WO2001084887A1

WO2001084887A1 - Ceramic heater

Info

Publication number: WO2001084887A1
Application number: PCT/JP2001/003777
Authority: WO
Inventors: Yasuji Hiramatsu; Yasutaka Ito
Original assignee: Ibiden Co., Ltd.
Priority date: 2000-04-29
Filing date: 2001-05-01
Publication date: 2001-11-08

Abstract

A ceramic heater comprises resistance heating body patterns on a substrate and buffer areas among the adjacent resistance heating body patterns so as to prevent thermal interference among the adjacent resistance heating body patterns. The controllability of the uniform temperature distribution in the heating surface of the substrate is especially excellent.

Description

Satsuki Itoda Ceramics

The present invention relates to a ceramic heater mainly used in the semiconductor industry, and more particularly to a ceramic heater excellent in uniform control of temperature distribution on a substrate heating surface.

In recent years, semiconductors have been used not only in the electronics industry but also as one of the indispensable components in various industries. For example, a typical semiconductor chip is manufactured by slicing a silicon single crystal into a predetermined thickness to produce a silicon wafer, and then forming a plurality of integrated circuits and the like on the silicon wafer.

In the manufacturing process of this semiconductor chip, a silicon wafer placed on an electrostatic chuck is subjected to various processes such as etching and CVD to form a conductive circuit or to apply a resin for resist. After that, heating and drying are performed. Ceramic heaters are often used for such treatments. For example, Japanese Patent Application Laid-Open Nos. Hei 11-43030 and Hei 4-43049 disclose ceramic ceramics made of carbide or nitride.

However, these techniques have a problem that the temperature distribution on the substrate heating surface tends to be non-uniform. For example, a ceramic heater as shown in FIG. 1 has a configuration in which resistance heating elements are arranged concentrically or spirally. In the case of such a resistive heating element pattern having an even arrangement, if the pattern is divided into two or more to be individually controlled, interference occurs due to each pattern. In this case, if power is applied excessively in one pattern, it will affect the temperature distribution of other patterns, and it will be impossible to control the temperature distribution accurately over the entire substrate. . An object of the present invention is to provide a ceramic having excellent controllability of uniform temperature distribution on a substrate heating surface. An object of the present invention is to provide a heater.

Another object of the present invention is to provide a plurality of heating element patterns provided on a single substrate, so that heat interference does not occur between adjacent resistance heating element patterns. The idea is to design the layout of the turns.

Five

Disclosure of the invention

The inventors have found that the problems with the prior art, especially when a single ceramic substrate is provided with a plurality of resistance heating element patterns composed of individually controllable circuits, In order to overcome the problem of non-uniform temperature distribution 0 due to heat interference between body patterns, we found that it is effective to provide a buffer area of appropriate size between each pattern. That is, the present invention is a ceramic heater according to the following gist configuration.

(1) In a ceramic heater having a plurality of resistance heating element patterns forming independent circuits on the surface or inside of the ceramic substrate, a buffer area is provided between the adjacent resistance heating element patterns. Is provided.

(2) The buffer region is a region for mitigating heat interference occurring between adjacent resistive heating element patterns.

(3) The ceramic substrate has a circular shape.

(4) The ceramic substrate is made of a carbide ceramic or a nitride ceramic.

(5) The surface of the ceramic substrate is covered with an insulating layer.

(6) The insulating layer is formed of a layer coated with an oxide ceramic.

(7) The buffer region has a width in a radial direction of the ceramic substrate and a size within a range of 0.5% to 35.5% of the substrate diameter.

(8) The buffer region has a width that is more than about twice the distance between the respective resistance heating elements in the resistance heating element pattern. (9) A ceramic heater having a resistance heating element formed on the surface or inside of a ceramic substrate, wherein a non-resistance heating element formation area is provided between resistance heating element formation areas comprising two or more circuits. Ceramic ceramic evening.

(10) The ceramic substrate according to the above (9) is characterized in that it has a disk shape. (Iii) The ceramic substrate according to the above (9) is characterized in that it is a charcoal nitride or a nitride ceramic.

(12) The width in the radial direction of the non-resistance heating element forming region is 0.5% to 35% of the diameter of the ceramic substrate.

(13) The width in the diameter direction of the non-resistance heating element formation region is characterized by exceeding twice the diametric width between the resistance heating elements constituting the resistance heating element formation region.

As described above, the present invention is a ceramic heater in which a plurality of resistance heating element patterns constituting independent circuits that are individually controlled are provided on the surface or inside of a ceramic substrate.

Thus, according to the present invention, by arranging two or more individually controllable resistance heating elements on the ceramic substrate, the temperature of the ceramic substrate can be controlled for each part. In particular, in the present invention, if a thermocouple, a thermopure, or the like is attached and the temperature of the ceramic substrate is measured, the applied power can be controlled for each resistance heating element pattern, and the temperature distribution on the substrate heating surface can be finely adjusted. Will be able to

As described above, when the temperature of the ceramic substrate is partially controlled, if a large area is applied to a specific resistance heating element pattern when the formation area of each resistance heating element pattern is close to each other, In addition, when the temperature of this portion rises, the influence spreads to other adjacent resistance heating element pattern formation regions, and furthermore, they interfere with each other. In this case, in general, the input power of the other (the latter) resistive heating element pattern must be reduced, and complicated temperature control is required, making it difficult to accurately control the temperature distribution on the heated surface. Become.

Therefore, in the present invention, a buffer area, which is a non-resistance heating element forming area, is provided between the respective resistance heating element patterns. This buffer area is composed of adjacent resistance heating element patterns This is a region for mitigating the thermal interference that occurs between one another. With such a buffer area, even if a large amount of electric power is applied to one resistive heating element pattern and the temperature of this area rises, the effect of the temperature rise is affected by the presence of the buffer area. Precise temperature distribution can be controlled without spreading to other resistance heating element pan formation areas.

For example, FIG. 2 shows that the temperature of a laminar heater having the conventional resistance heating element pattern shown in FIG. 1 is raised to 140 ° C., and a semiconductor wafer at 25 ° C. is placed on the surface of the ceramic substrate. FIG. 9 shows a temporal change in temperature in the middle, center, and outer peripheral portions of the ceramic substrate when held at an interval of 0 zm. In this conventional ceramic heater, the temperature of each part did not stabilize and the temperature distribution was not even after 40 seconds as shown in the figure. On the other hand, in the case of the ceramic heater having the resistive heating element pattern according to the present invention shown in FIG. 4, due to the existence of the buffer area, the settling has already been set after the elapse of 40 seconds as shown in FIG. The temperature distribution is almost completely uniform. As described above, in the ceramic heater of the present invention, the buffer area is provided between each of the individually controlled resistance heating element patterns, so that the influence of the temperature change of another adjacent resistance heating element pattern can be reduced. This can be eliminated or reduced, and uniform control of the temperature distribution on the heating surface of the ceramic substrate can be performed quickly and accurately.

The ceramic heater of the present invention is formed by combining concentric, spiral, and bent (wavy) resistance heating element patterns and disposing them in the radial direction. The buffer area, that is, the area where the resistance heating element pattern is not formed, is an area where the resistance heating element pattern is formed and an area where another resistance heating element circuit is formed adjacent to the area. And where no so-called resistance heating element is formed.

In particular, when a spiral or concentric pattern is formed on a circular ceramic substrate, the size (distance) of the buffer area in the radial direction of the substrate is determined by the distance between adjacent resistance heating elements in each pattern. It is desirable to make the width larger than the space between them, especially more than twice (radial space). The size (interval) in the radial direction of the substrate between the patterns of the resistance heating elements and the turns is 0.5% to 35%, preferably 0.5% to 35%, in the radial direction (width) of the circular ceramic substrate. Should be about 5% to 30%. In this regard, if the width of the buffer area between the respective resistive heating element patterns is smaller than the above-mentioned width, or if the spacing in the radial direction of the ceramic substrate is less than 5%, heat interference occurs. If it exceeds 0%, the temperature in the buffer region becomes too low, and in any case, the temperature distribution on the heating surface tends to be uneven. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a rear view of a ceramic substrate illustrating a conventional resistance heating element pattern, FIG. 2 is a graph showing a temperature distribution of a conventional ceramic heater, and FIG. 3 is a temperature distribution of a ceramic heater according to the present invention. FIG. 4 is a rear view of a ceramic substrate illustrating a resistance heating element pattern according to the present invention, and FIG. 5 is a partial cross-sectional view of the ceramic heater, which is partially cut away. FIG. BEST MODE FOR CARRYING OUT THE INVENTION

The ceramic substrate of the present invention uses a nitride ceramic or a carbide ceramic as a ceramic substrate, and preferably forms an oxide ceramic insulating layer on the surface thereof. This is because nitride ceramics as a substrate material tend to have a low volume resistance at high temperatures due to solid solution of oxygen and the like, and carbide ceramics have conductivity unless they are highly purified. By coating the substrate with an oxide ceramic, a short circuit between the patterns can be prevented even at high temperatures or even when impurities are contained, and the temperature controllability can be further facilitated.

Examples of the nitride ceramic constituting the ceramic substrate include metal nitride ceramics, for example, aluminum nitride, silicon nitride, boron nitride, titanium nitride, and the like. The above-mentioned carbide ceramics include metal carbide ceramics, for example, silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, tanste carbide. And the like. It should be noted that an oxide ceramic may be used as the ceramic substrate, and alumina, silica, glasslite, mullite, zirconia, beryllia, and the like can be used.

It is desirable to include a sintering aid in the ceramic substrate material. For example,

5 Alkali metal oxides, alkaline earth metal oxides, and rare earth oxides can be used as sintering aids for aluminum nitride. Among these sintering aids, CaO, Y ₂ 〇 _3, Na ₂ 0, Li. 〇, Rb ₂ 0 ₃ are preferred. Also, alumina may be used. The content of these sintering aids is desirably 0.1 to 20 wt%. In the case of silicon carbide, it is preferable to use B ₄ C, C, or ALN as a sintering aid.

It is desirable that the ceramic substrate contains about 5 to 500 ppm of carbon. By including carbon in the substrate material, the ceramic substrate can be blackened, and when used as a heater, the radiation characteristics of radiant heat can be expected to be improved. The carbon may be amorphous or crystalline. When amorphous carbon is used, it is possible to prevent a decrease in volume resistivity at high temperatures, and when using crystalline one, it is possible to prevent a decrease in thermal conductivity at high temperatures. Because you can. Therefore, depending on the application, both crystalline carbon and amorphous carbon may be used in combination. Further, the content of carbon is more preferably 50 to 2000 ppm.

0 It is desirable that the ceramic substrate has a diameter of 20 Omm or more, especially 12 inches (300 mm) or more. This is because it can be adapted to the next generation of semiconductor wafers. The thickness is preferably 5 Omm or less, particularly preferably 25 mm or less. The reason is that when the thickness of the ceramic substrate exceeds 25 mm, the heat capacity of the ceramic substrate becomes large, and the temperature follow-up property in the case of heating and cooling via the temperature control means 5 is reduced. In this sense, it is optimal that the thickness of the substrate is about 5 mm or more, and the thickness is preferably more than 1.5 mm. As the insulating layer covering the surface of the substrate, an oxide ceramic is desirable, and specifically, silica, alumina, mullite, cordierite, beryllia, or the like can be used. Alternatively, the insulating layer may be formed by subjecting a sol solution obtained by hydrolyzing and polymerizing an alkoxide to spin coating, followed by baking, or by performing a treatment such as sputtering or CVD. In addition, the insulating layer may be an oxide layer formed by oxidizing the surface of a ceramic substrate.

In the ceramic heater of the present invention, the semiconductor wafer is directly mounted on the surface (heating surface) of the ceramic substrate on which the wafer is mounted, and the semiconductor wafer is supported on support pins (reflection pins) or spacers. For example, a certain distance may be interposed between the ceramic substrate and the wafer and held. In this case, the distance between the substrate heating surface and the semiconductor wafer is desirably about 5 to 500 μm.

In the ceramic substrate, a bottomed hole 6 can be provided as needed to embed a thermocouple as a side temperature element. This is because the temperature of the ceramic substrate is measured by the thermocouple, and based on the data, the voltage and the current to each resistance heating element pattern are changed to effectively control the temperature distribution of the entire substrate. The size of the junction of the metal wires of the thermocouple should be the same as or larger than the diameter of each metal wire. For example, 0.5 mm or less is preferable. With this configuration, the heat capacity of the junction is reduced, and the temperature can be accurately and quickly converted to a current value. As a result, the temperature controllability is improved, and the difference in the temperature distribution on the substrate heating surface can be reduced.

As the thermocouple, for example, as shown in JIS-C-162 (1980), K-type, R-type, B-type, S-type, E-type, J-type and T-type Can be used. This thermocouple may be bonded to the bottom of the bottomed hole using gold brazing, silver brazing, or the like, or may be inserted into the bottomed hole and sealed with a heat-resistant resin. Well, both may be used in combination. As the heat-resistant resin, for example, a thermosetting resin, particularly, an epoxy resin, a polyimide resin, a bismaleimide-triazine resin, or the like can be used. These resins may be used alone or in combination of two or more. Also, For gold brazing, it is selected from 37-80.5wt% Au-63-; L9.5wt% Cu alloy, 81.5-82.5wt Au-18.5-17.5wt% Ni alloy At least one is preferred. These are because the melting temperature is 900 ° C or higher, and it is difficult to melt even in a high temperature region. As the silver solder, for example, an Ag—C 11-based solder can be used.

In the ceramic heater of the present invention, as shown in FIG. 4, it is necessary that the resistance heating element is divided into at least two or more patterns composed of independent circuits that can be controlled individually. More preferably, it is divided into the following patterns. Since the resistance heating element pattern is divided into a plurality of parts, the amount of heat generated is changed by individually controlling the power supplied to each resistance heating element pattern, and the temperature distribution of the entire substrate, that is, the temperature of the wafer heating surface The distribution can be finely adjusted. As examples of the pattern of the resistance heating element, concentric, spiral, eccentric, bent (wavy), etc. are well suited.

When forming a resistive heating element pattern on the surface of a ceramic substrate, a conductive paste containing metal particles is applied to the surface of the ceramic substrate to form a conductive paste layer having a predetermined pattern, which is then baked. And firing the above metal particles. The firing of the metal particles is desirably performed so that the metal particles fuse with each other and between the metal particles and the ceramic.

FIG. 4 is an example of a preferred embodiment of the resistance heating element pattern of the present invention. In this example, a concentric resistive heating element pattern 2a is provided on the front surface (substrate back surface) of the ceramic substrate 1 opposite to the non-heated surface, a central portion is provided with two concentric resistive heating elements, The resistance heating element patterns 2b, 2b, and the outer periphery are divided into four wavy resistance heating element patterns 2c in the circumferential direction, each with a buffer area 3 It was formed.

In other words, between the resistive heating element pattern 2a and the resistive heating element pattern 2b, between the resistive heating element pattern 2b, and the resistive heating element pattern 2c, and at the peripheral portion of the substrate, in the circumferential direction. Four adjacent resistance heating element patterns 2c A fixed size buffer area 3 is provided. Due to the presence of the buffer region 3, for example, even if a large amount of power is applied to the resistance heating element pattern 2 b and the temperature rises, the buffer region 3 exists, and concentric circular resistance heating element patterns 2 a and The wavy resistance on the outside has no effect on the heating element pattern 2c and does not interfere with each other.c Therefore, the temperature such as lowering the temperature of the resistance heating element pattern 2a or the resistance heating element pattern 2c No control is required, and the temperature difference on the heated surface of the substrate can be reduced quickly with simple control.

Each of the resistance heating element patterns 2 a, 2 b, 2 b ′, and 2 c is formed in a concentric, spiral, or bent (wave-shaped) pattern as described above. It is desirable to form a circuit in the evening formation region. This is because it is easier to control if the control unit is a single circuit.

The thickness of the resistance heating element itself is preferably about 1 to 30 m, more preferably 1 to 10 m.

When the resistive heating element is patterned on the surface of the ceramic substrate 1, the line width of the resistive heating element is preferably about 0.1 to 20 mm, more preferably about 0.1 to 5 mm. . Such a resistance heating element can vary its resistance value depending on its width and thickness, but the above range is the most practical. The resistance value increases as the thickness decreases and the resistance decreases.

By arranging the resistance heating element as described above, the heat generated from the resistance heating element is diffused throughout the ceramic substrate while propagating in the thickness direction of the substrate, and the object to be heated (silicon wafer) The temperature distribution on the surface where the object is heated is made uniform, and as a result, the temperature in each part of the object to be heated is made uniform.

This resistance heating element may have a rectangular or elliptical cross section, but is preferably flat. This is because the flattened surface is more scattered toward the wafer heating surface, and thus it is difficult to achieve a non-uniform temperature distribution on the wafer heating surface. That is, the aspect ratio (width of the heating element / thickness of the heating element) of the cross section of the resistance heating element is desirably about 10 to 500,000. Adjusting this range will increase the resistance of the heating element. This is because the uniformity of the temperature of the wafer heating surface can be ensured. When the thickness of the heating element is constant, if the aspect ratio is smaller than the above range, the amount of heat transmitted in the direction of the heating surface of the ceramic substrate 1 to the wafer decreases, and the heat distribution approximated to the pattern of the heating element becomes smaller. It occurs on the heated surface, and conversely the aspect ratio

"5 If it is too large, the temperature directly above the center of the resistance heating element will be high, and eventually a temperature distribution similar to the pattern of the heating element will be generated on the wafer heating surface. Then, it is preferable that the aspect ratio of the cross section is 10 to 500. The aspect ratio of the resistance heating element is as follows when the resistance heating element is formed on the surface of the substrate. If it is formed inside, it is desirably 200 to 500,000.

The aspect ratio can be increased when the resistance heating element is formed inside the substrate. However, when the resistance heating element is provided inside, the distance between the wafer heating surface and the heating element becomes shorter, and This is because it is necessary to make the heating element itself flat because the temperature uniformity of the heating element decreases.

5 The conductive paste for forming such a resistance heating element is not particularly limited, but contains metal particles or conductive ceramic for ensuring conductivity, and also contains a resin, a solvent, a thickener, etc. Is preferred. As the metal particles, for example, noble metals (gold, silver, platinum, palladium), lead, tungsten, molybdenum, nickel and the like are preferable. These may be used alone or in combination of two or more. This is because these metals are relatively hard to oxidize and have sufficient resistance 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. If it is too small, less than 0.1 m, it is liable to be oxidized, while if it exceeds 100 m ', sintering becomes difficult and the resistance value becomes large. The shape of the metal particles may be spherical or scaly. Use these metal particles -In that case, it 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 heating element and the nitride ceramic is improved. This is advantageous because it can ensure that the resistance can be increased.

5 Examples of the resin used for the conductor base include an epoxy resin and a phenol resin. Examples of the solvent include isopropyl alcohol. Examples of the thickener include cellulose.

As described above, it is desirable that the conductor paste is formed by adding a metal oxide to metal particles and sintering the metal particles and the metal oxide as a resistance heat generator. As described above, by sintering the metal oxide together with the metal particles, the ceramic substrate, ie, the nitride ceramic or the carbide ceramic, can be brought into close contact with the metal particles. That is, it is not clear why mixing metal oxides improves the adhesion to nitride ceramics or carbide ceramics, but the surface of metal particles and the surfaces of nitride ceramics and carbide ceramics are slightly oxidized. This does not mean that the oxide films are formed by sintering through the metal oxide to form an integrated film, thereby improving the adhesion between the metal particles and the nitride ceramic or the carbide ceramic. It is thought.

As the above-mentioned metal oxide, for example, at least one selected from the group consisting of lead oxide, zinc oxide, silica, boron oxide (B ₂ 〇 ₃ ), alumina, methanol and titania is preferable. This is because these oxides can improve the adhesion between the metal particles and the nitride ceramic or the carbide ceramic without increasing the resistance value of the heating element.

The lead oxide, zinc oxide, silica, boron oxide (B ₂ 0 _3), alumina, Itsutori §, the proportion of titania, when the 1 0 0 parts by weight of the total amount of the metal oxide, by weight, 5 lead oxide But:! ~ 10, silica 1 ~ 30, boron oxide 5 ~ 50, zinc oxide 20 ~ 70, alumina; ~ 10, yttria is 1 ~ 50, titania is 1 ~ 50, and the total is preferably adjusted within a range not exceeding 100 parts by weight. By adjusting the amounts of these oxides within these ranges, the adhesion to nitride ceramics can be particularly improved.

The amount of the metal oxide to be added to the metal particles is preferably from 0.1 wt% to less than 10 wt%. Further, when the heating element is formed by using the conductor paste having such a configuration, the sheet resistivity is preferably 1 to 45 πιΩ / port.

If the sheet resistivity exceeds 45 πιΩΖ, the calorific value becomes too small with respect to the applied voltage, and it is difficult to control the calorific value of a ceramic substrate provided with a resistive heating element on its surface. If the added amount of the metal oxide is 1 O wt% or more, the sheet resistivity exceeds 50 πιΩΖ, and the calorific value becomes too small, so that the temperature control becomes difficult and the uniformity of the temperature distribution decreases. I do.

When the resistance heating element is formed on the surface of the substrate, the surface of the heating element is desirably covered with a metal coating layer 8 as shown in FIG. This is to prevent the internal resistance heating element (metal sintered body) from being oxidized and changing the resistance value. The thickness of the metal covering layer 8 to be formed is preferably 0.1 to 10 zm. The metal used for forming the metal coating layer 8 is not particularly limited as long as it is a non-oxidizing metal. Specific examples include gold, silver, palladium, platinum, and nickel. Can be These may be used alone or in combination of two or more. Of these, nickel is preferred.

The resistance heating element 2 requires a connection terminal 9 with pins for connecting to an external power supply. The connection terminal 9 is attached to the resistance heating element 2 via a solder layer 10. This is because the thermal diffusion of the solder is prevented. Examples of the connection terminal 9 include, for example, terminal pins made of console.

When the connection terminal 9 is connected, an alloy such as silver-lead, lead-tin, and bismuth tin can be used as the solder. The thickness of the solder layer 10 is preferably 0.1 to 50 m. This is because the range is sufficient to secure connection by soldering. Next, a method of manufacturing the ceramic heater of the present invention will be described.

Here, a manufacturing method in which a resistance heating element is formed inside a ceramic heater is described. explain.

(1) Manufacturing process of ceramic substrate

A slurry is prepared by mixing a sintering aid such as yttria or a binder as necessary with the powder of the above-mentioned nitride ceramic or carbide ceramic, and then preparing the slurry.

-5 Make granules into granules by spray-drying, etc., and place the granules in a mold or the like and pressurize them into a plate-like shape to produce a green body.

Next, in order to embed a temperature measuring element such as a thermocouple or a portion serving as a through hole 4 into which a lift pin 5 for supporting a silicon wafer can be vertically moved as required, in the above-described formed body. The portion which becomes the bottomed hole 6 of the above is formed.

Next, the formed body is heated, fired, and sintered to produce a ceramic plate. After that, the ceramic substrate 1 is manufactured by processing into a predetermined shape, but may be a shape that can be used as it is after firing. In addition, by performing heating and firing while applying pressure, it is possible to manufacture a ceramic substrate 1 having no pores. Heating and firing may be performed at a temperature equal to or higher than the sintering temperature. However, in the case of nitride ceramic 5 or carbide ceramic, the temperature is 100 to 250 ° C.

(2) Process of printing conductor paste for resistance heating element on ceramic substrate

The conductor paste is generally a high-viscosity fluid composed of metal particles, a resin, and a solvent. The conductor paste is printed on the portion where the resistance heating element is to be provided by screen printing or the like to form a conductor paste layer. The resistance heating element should be printed in a pattern as shown in Fig. 4 because it is necessary to keep the entire substrate at a uniform temperature. The conductor paste layer is desirably formed so that the cross section of the resistance heating element 2 after firing is rectangular and flat.

(3) firing of conductive paste

The conductor paste layer printed on the bottom surface of the ceramic substrate 1 is heated and baked to remove the resin and the solvent, and the metal particles are sintered and baked on the bottom surface of the substrate 1 to form the resistance heating element 2 . The heating and firing temperature is preferably from 500 to 100 ° C.

If the above-mentioned metal oxide is added to the conductor paste, the metal particles, substrate and Since the metal oxide and the metal oxide are sintered and integrated, the adhesion between the resistance heating element 2 and the ceramic substrate 1 is improved.

(4) Formation of metal coating layer

It is desirable to provide a metal coating layer 8 on the surface of the resistance heating element 2. The metal coating layer 8 can be formed by electrolytic plating, electroless plating, sputtering or the like, but in consideration of mass productivity, electroless plating is optimal.

(5) Installation of terminals, etc.

A connection terminal 9 for connection to an external power supply is attached to an end of the pattern of the resistance heating element 2 via a solder layer 10. In addition, thermocouples are fixed to the bottomed holes 6 with silver braze, gold braze, etc., sealed with polyimide or other heat-resistant resin, and the production of ceramic heaters is completed.

.

In the ceramic heater of the present invention, an electrostatic electrode may be provided to serve as a static chuck, or a cap top conductor layer may be provided to serve as a wafer prober. 5 Example

(Example 1) Manufacture of ceramic ceramic made of aluminum

(1) A composition consisting of 100 parts by weight of aluminum nitride powder (average particle size: 1.1 u), 4 parts by weight of yttria (average particle size: 0.4 urn), 12 parts by weight of acryl-based binder and alcohol is spray-dried. A granular powder was produced.

0 (2) Next, the above granular powder was placed in a mold and molded into a flat plate to obtain a green compact. The green sheet is drilled to form a through hole 4 for inserting a pin 5 of a silicon wafer and a bottomed hole 6 for embedding a thermocouple (diameter: 1.1 mm, depth 2 mm).

(3) The processed compact was hot-pressed at 1800 ° C and a pressure of 200 kg / cm to obtain a 5 mm-thick 3 mm thick aluminum plate.

Next, a disk having a diameter of 8 inches (210 mm) was cut out from the plate to obtain a ceramic plate (ceramic substrate 1). (4) A conductive paste was printed on the ceramic substrate 1 obtained in the above (3) by screen printing. The printing patterns were two concentric patterns and four wavy patterns on the outer periphery as shown in FIG. The distance between the resistance heating element pattern 2a and the resistance heating element pattern 2b is 1 mm, the distance between the resistance heating element pattern 2b and the resistance heating element pattern 25c is 20mm, and the resistance heating element pattern 2 c The distance between them is 8 mm.

The distance between the circumferentially adjacent resistance heating element patterns 2c is 8 mm. Also,

-The distance between each heating element in each resistance heating element pattern was 1 mm.

As the conductive paste, Solvent PS 603D manufactured by Tokuka Chemical Laboratory, which is used for forming through holes in printed wiring boards, was used. This conductive paste is a silver-lead paste, and based on 100 parts by weight of silver, lead oxide (5 wt%), zinc oxide (55 wt%), silica (10 wt%), boron oxide (25 wt%) and It contained 7.5 parts by weight of metal oxide consisting of alumina (5 wt%). The silver particles had an average particle size of 4.5 μm and were scaly.

(5) Next, the ceramic substrate on which the conductive paste is printed is heated and fired at 780 ° C. 5 to sinter the silver and lead in the paste and to bake the substrate 1 to generate resistance heat. Body 2 formed. The silver-lead resistance heating element 2 had a thickness of 5 m, a width of 2.4 mm, and an area resistivity of 7.7 πιΩ / m2.

(6) The ceramic substrate 1 prepared in (5) above was treated with nickel sulfate 80 g / l, sodium hypophosphite 24 g / l, sodium acetate 12 g / l, boric acid 8 g / l, and ammonium chloride 6 gZl. The metal coating layer (nickel layer) 8 having a thickness of 1 m was deposited on the surface of the silver-lead resistance heating element 2 by immersing it in an electroless nickel plating bath composed of an aqueous solution.

(7) A silver-lead solder paste (manufactured by Tanaka Kikinzoku) was printed by screen printing on the portion where the connection terminals 9 with pins for securing connection to the power supply were to be formed, thereby forming a solder layer 150. Next, Kovar external terminal connection pins 9 were placed on the solder layer 10 and reflowed by heating at 420 ° C., and the connection terminals 9 were attached to the surface of the resistance heating element 2. (8) A thermocouple was buried in the bottomed hole 6 for temperature control, filled with polyimide resin, and baked at 190 ° C for 2 hours to obtain a ceramic heater (Fig. 4). .

(Example 2) Manufacture of ceramic powder with resistance heating element inside

(1) Aluminum nitride powder (manufactured by Tokuyama, average particle size: LI j), yttria (average particle size: 0.4 jam), 4 parts by weight, acrylic binder, 11.5 parts by weight, dispersing agent, 0.5 parts by weight A green sheet having a thickness of 0.47 mm was obtained by molding using a paste obtained by mixing 53 parts by weight of alcohol composed of ethanol and ethanol by a dough plate method.

(2) Next, after drying this green sheet at 80 ° C for 5 hours, a through hole 4 into which a 1.8 mm, 3.0 mm, and 5.0 mm diameter silicon wafer riff pin 5 is inserted by punching And a part to be a through hole (connection pad) for connection with the connection terminal pin 9 were provided.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of l〃m, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of ethereal solvent, and 0.3 parts by weight of a dispersant are mixed to form a conductive paste. A was prepared.

A conductive paste B was prepared by mixing 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of a terpionone solvent, and 0.2 parts by weight of a dispersant. Prepared.

The conductive paste A was printed on a green sheet by a screen printing method to form a conductive paste layer. As the printing pattern, three concentric patterns as shown in FIG. 4 were formed near the center and four wavy patterns were formed on the outer periphery. The distance between the resistance heating element pattern 2a and the resistance heating element pattern 2b is 7 O mm, the distance between the resistance heating element pattern 2b and the resistance heating element pattern 2c is 20 mm, and The distance between the heating elements is 2 mm.

Further, in order to connect the connection terminal 9 to the resistance heating element 2 provided inside the substrate, the through-hole provided in the substrate 1 was filled with the conductive paste B.

Tungsten paste is further printed on the green sheet after the above processing -37 green sheets not to be laminated were stacked on the upper side (heating surface) and 13 on the lower side at 130 ° C and a pressure of 80 kg / cm.

(4) Next, the obtained laminate was degreased in a nitrogen gas at 600 ° C for 5 hours, and subjected to a hot press at 1890 ° C and a pressure of 150 kg / cm for 3 hours to form a 3 mm-thick aluminum nitride 5 plate. I got a body. This is cut out into a 210mm disk, with a thickness of 6 zm and a width of 1

A ceramic heater having a 0 mm resistance heating element embedded therein was obtained.

(5) Next, after polishing the plate-like body obtained in (4) with a diamond grindstone, a mask is placed, blasting is performed with glass beads, and bottomed holes for thermocouples 6

(Diameter: 1.2 mm, depth: 2.0 mm).

0 (6) Further, a part of the hole for the through hole is cut out to form a concave portion, and a gold solder made of Ni—Au is used in the concave portion, and heated and reflowed at 700 ° C. to form an outer portion made of Kovar. The connection terminal 9 for power supply connection was fixed.

The connection of the connection terminals 9 is desirably a structure that supports the tungsten support at three points. This is because connection reliability can be ensured.

5 (7) Next, the thermocouple of Example 1 for temperature control was inserted and buried in the bottomed hole 6, embedded with a silicon sol, and dried at 100 ° C for 1 hour to produce a ceramic heater. Completed.

(Comparative Example 1)

As in Example 1, a single concentric resistive heating element pattern 2 having spirals having different diameters arranged on the entire substrate as shown in FIG. The diameter of the ceramic substrate 1 is 210 mm, the resistance heating element pattern is 2.4 mm, the distance between the patterns-is 2.4 mm, and the radial width between the resistance heating elements is 4.8 mm.

(Comparative Example 2)

It is the same as in Example 1, but has three spiral (concentric) patterns as shown in FIG. 1, and four wavy patterns on the outer periphery. The distance between the resistive heating element pattern 2a and the resistive heating element pattern 2b is 77mm, the distance between the resistive heating element pattern 2b and the resistive heating element pattern 2c is 20mm, and the distance between the adjacent Resistance heating element pattern The distance between 2c is 0.8 mm. The distance between the resistance heating elements in the resistance heating element pattern is l mm.

The ceramic heaters of Example 1 and Comparative Example 1 were connected to a temperature controller (Omron E5ZE) equipped with a calculation unit, a power supply unit, and a control unit, and the temperature was raised to 140 ° C. Over time, the change in the surface temperature of the ceramic substrate over time was measured when the wafer with the temperature sensor at 25 ° C. was held close to a distance of 100 μm. The results are shown in FIGS. 2 and 3. FIG. 3 shows Example 1 and FIG. 2 shows Comparative Example 1.

In Example 1, the temperature returned to 140 ° C. after the elapse of 40 seconds, and was completely settled. However, in Comparative Example 1, it was not settled even after 40 seconds had elapsed. It took 60 seconds to settle.

The settling time for the example and the comparative example, and the temperature difference of the heated surface temperature when heated to 200 ° C. were measured. The results are shown in Table 1 below.

Table 1

From the above results, according to the ceramic heater of the present invention, it was confirmed that the temperature distribution on the heating surface can be easily and reliably uniformized with a simple control when the resistance heating element is divided into a plurality and controlled. .

Industrial applicability

INDUSTRIAL APPLICABILITY The ceramic heater of the present invention is used for an apparatus for manufacturing a semiconductor or inspecting a semiconductor. Examples include an electrostatic chuck, a wafer prober, and a susceptor. When used as an electrostatic chuck, in addition to the resistance heating element, an electrostatic electrode,

When the RF electrode is used as a wafer prober, a check top conductor layer is formed on the surface as a conductor, and the guard electrode and ground electrode are conductive inside. It is formed as a body. Further, the ceramic substrate for a semiconductor device of the present invention is preferably used at 100 ° C. or higher, preferably 200 ° C. or higher. The upper temperature limit is 800 ° C.

Claims

The scope of the claims

(1) In a ceramic heater having a plurality of resistive heating element patterns constituting independent circuits on the surface or inside of a ceramic substrate, a buffer area is provided between the adjacent heating element patterns. A special feature of Ceramic Hi.

(2) The ceramic capacitor according to claim 1, wherein the buffer region is a region for mitigating heat interference occurring between adjacent resistive heating element patterns.

(3) The ceramic heater according to claim 1, wherein the ceramic substrate is circular.

(4) The ceramic heater according to claim 1, wherein the ceramic substrate is a carbide ceramic or a nitride ceramic.

(5) The ceramic heater according to claim 1, wherein the surface of the ceramic substrate is covered with an insulating layer.

(6) The ceramic heater according to claim 5, wherein the insulating layer is a layer coated with an oxide ceramic.

(7) The ceramic heater according to claim 1, wherein the buffer region has a width in a radial direction of the ceramic substrate and a size within a range of 0.5% to 35% of a substrate diameter. .

(8) The ceramic storage device according to (1) or (7), wherein the buffer area has a width that is more than about twice a distance between the respective resistance heating elements in the resistance heating element pattern.

(9) A ceramic heater having a resistance heating element formed on the surface or inside of a ceramic substrate, wherein a non-resistance heating element formation area is provided between resistance heating element formation areas comprising two or more circuits. Ceramic ceramic evening.

(10) The ceramic heater according to (9), wherein the ceramic substrate has a disk shape.

(11) The ceramic substrate is made of a carbide or nitride ceramic. A ceramic holster according to claim 9.

(12) The ceramic heater according to (9), wherein a radial width of the non-resistance heating element-free region is 0.5% to 35% of a diameter of the ceramic substrate.

(13) The diametrical width of the resistance heating element non-formation area is more than twice the diametrical width between the resistance heating elements forming the resistance heating element formation area. Ceramic hero evening.