JP2002313533A - Planar ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar ceramic heater with excellent durability, always securing stable heat generation and heat radiation by stably ensuring electric power supply to a resistance heating element by an electric power supply terminal. SOLUTION: This planar ceramic heater has a planar ceramic base material 2 one main face of which forms a radiating-heating face; a resistance heating element 3 arranged being embedded in the ceramic base material 2; and an electric power supply terminal 1 with one end connected to the resistance heating element 3 and with the other end side led out to the other main face side of the ceramic base material 2. At least the outer peripheral surface, exposed to a high-temperature atmosphere, of the electric power supply terminal 1 is covered with a plated layer 1b of gold, platinum or a double-layer form of gold and platinum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar ceramic heater, and more particularly, to a planar ceramic heater which imparts oxidation resistance to a power supply terminal to maintain stable heat radiation and heat generation.

For example, in the production of semiconductors, semiconductor wafers are subjected to processing such as PVD, plasma CVD, plasma etching, and optical etching.
In addition, these processings are generally performed while arranging a workpiece on the surface of a planar ceramic heater (heating element) and heating the workpiece. In order to obtain a semiconductor having high performance or high reliability with good yield and mass production, heat treatment is one important factor.

[0003] Here, the planar ceramic heater includes, for example, a resistance heating wire (or a coil) such as a tungsten wire or a molybdenum wire inside a dense and gas-tight ceramic sintered body (ceramic base material), for example, a spiral or ceramic wire. It is buried in a zigzag shape. The power supply terminal for the resistance heating element has a structure led out of the ceramic base. The power supply terminal is made of, for example, tungsten, molybdenum, nickel, or the like, and the ceramic base is made of, for example, alumina, silica, aluminum nitride, silicon nitride, or sialon. Aluminum nitride is attracting attention in terms of thermal conductivity and corrosion resistance.

[0004] This type of ceramic heater is
Generally, it is manufactured by the following means. The first means is to dispose a resistance heating element formed by the resistance heating wire on one main surface of a base material (green sheet) for a ceramic base, and to stack a heater cover sheet on the resistance heating element surface while supplying power. In this method, the terminals are inserted into and incorporated into the cover sheet, and then subjected to degreasing under predetermined conditions, hot pressing at a required temperature, and the like, followed by sintering and integration.

[0005] A second means is to prepare a plate-shaped ceramic base material forming a heat-radiating / heat-generating surface and a plate-shaped ceramic base material forming a heater cover in advance. This is a method in which a resistance heating element formed by a heating wire is arranged, and a bonding agent layer is interposed to be joined and integrated. Here, a hole corresponding to a connected portion of the resistance heating element is formed in the plate-shaped ceramic base material forming the heater cover, and a power supply terminal is attached to the formed hole, and the conductive material is electrically conductive. The electrical connection is made by filling the paste. In any of the first and second means, the formation of the resistance heating element is also performed by screen printing of a paste for the resistance heating element, laser processing of a tungsten plate, punching punching, or the like.

[0006]

By the way, in the heat treatment in the semiconductor manufacturing process, the durability and good yield of the planar ceramic heater used as a heat source are ensured in view of the working rate and cost reduction. Is assumed. In other words, the planar ceramic heater is required to maintain stable heat radiation / heat generation capacity, uniformity of in-plane temperature distribution, and the like. However, in the configuration of the conventional planar ceramic heater, the power supply terminal is likely to be deteriorated, and there are problems in durability, stable heat radiation, heat generation, and the like.

That is, when the planar ceramic heater is mounted, for example, as a member of a semiconductor manufacturing apparatus, a heat radiating / heating main body (ceramic base material in which a resistance heating element is embedded) mounts and processes a semiconductor wafer. Therefore, it is mounted in a processing chamber where the atmosphere can be appropriately adjusted. On the other hand, the power supply terminal is usually led out through the wall of the processing chamber into the atmosphere outside the processing chamber, and is set so as to easily supply required power from the outside.

[0008] Further, in the configuration of the manufacturing apparatus, it can be said that the power supply terminal is led out to the atmosphere when the planar ceramic heater performs a heat radiation / heat generation operation.
The temperature rises to a considerably high temperature because it is adjacent to the processing chamber of several hundred degrees Celsius. That is, the power supply terminal made of tungsten inevitably takes a state of being exposed to the high-temperature atmosphere, so that the oxidation reaction proceeds in the exposed region. In addition, the progress of the oxidation reaction not only causes a decrease in the power supply capacity or power supply capability of the power supply terminal, but also causes a decrease in mechanical strength of the power supply terminal, greatly impairing durability and the like. Become.

As described above, in the case of the conventional planar ceramic heater, there is a possibility that heat generation and heat dissipation may be impaired due to a function deterioration phenomenon caused by oxidation of the power supply terminal. That is, the difficulty in constantly supplying the required power and the difficulty in ensuring uniformity of the in-plane temperature distribution impair, for example, semiconductor manufacturing / processing efficiency or productivity. In addition, such a problem poses a serious problem in increasing productivity and the like by increasing the diameter of a semiconductor wafer. In other words, in order to cope with the increase in the diameter of the workpiece, the diameter of the planar ceramic heater needs to be increased, and at this time, the stability of heat radiation and heating temperature required for the planar ceramic heater is impaired. This means that it is not possible to respond to improvements in productivity.

The present invention has been made in view of the above circumstances, and has an excellent durability in which power supply from a power supply terminal to a resistance heating element is stably ensured, and stable heat generation and heat radiation are always obtained. The purpose is to provide a ceramic heater.

[0011]

According to a first aspect of the present invention, there is provided a planar ceramic base material having one main surface serving as a heat radiating / heating surface, a resistance heating element embedded and arranged in the ceramic base material, A planar ceramic heater having one end connected to the resistance heating element and the other end side having a power supply terminal led out to the other main surface side of the ceramic base, wherein the outer periphery of the power supply terminal is exposed to at least a high-temperature atmosphere; A surface ceramic heater characterized in that the surface is coated with gold, platinum or a multi-layer plating of gold and platinum.

According to a second aspect of the present invention, in the planar ceramic heater according to the first aspect, the plating layer to be coated is formed as a plurality of layers in the order of a gold plating layer and a platinum plating layer.

According to a third aspect of the present invention, in the planar ceramic heater according to the first or second aspect, the thickness of the plating layer to be coated is 5 to 70 μm.

According to the first to third aspects of the present invention, a resistance heating element is embedded and arranged in a planar ceramic substrate, and the other end of a power supply terminal having one end connected to the resistance heating element is placed outside the ceramic substrate. In the configuration of the derived planar ceramic heater, at least the outer peripheral surface of the power supply terminal exposed to the high temperature atmosphere is coated with a gold plating layer, a platinum plating layer, or a gold plating layer and a platinum plating layer to provide oxidation resistance The main point is what you do. That is, by coating the outer peripheral surface of the power supply terminal, which is easily heated to a high temperature and exposed to the atmosphere, with a thin layer of a noble metal that is chemically stable even at a high temperature, the contact with the air is cut off and the power supply terminal is connected to the power supply terminal. Maintain and demonstrate stable functions or performance.

In the first to third aspects of the present invention, the planar ceramic base material is, for example, an alumina-based or silica-based
Examples thereof include aluminum nitride, silicon nitride, and sialon. Aluminum nitride is particularly preferable in terms of thermal conductivity and corrosion resistance. The resistance heating element embedded and arranged in the ceramic substrate is formed by forming a resistance heating wire (or coil) such as a tungsten wire, a molybdenum wire, a nichrome wire or the like in a spiral or zigzag shape. Further, the power supply terminal having a structure led out of the ceramic base is made of, for example, tungsten, molybdenum, nickel, Inconel, Kovar, Super Invar, or the like.

In the first to third aspects of the present invention, the metal forming the plating layer covering at least the outer peripheral surface of the power supply terminal exposed to the high-temperature atmosphere is gold or platinum. Here, the coating plating layer is selected according to the material and use of the power supply terminal. For example, when the power supply terminal is made of tungsten, a gold plating layer, a gold plating layer—a platinum plating layer, or a gold plating layer—a platinum plating layer—a gold plating layer—a platinum plating layer is selected.

That is, the plating layer coating of the power supply terminal is
It is desirable to select a combination exhibiting affinity with the material of the power supply terminal. Here, the thickness of the plating layer is about 5 to 70 μm, and preferably about 10 to 30 μm in either case of a single layer or a laminated type. If the thickness is small, pinholes remain and corrosion resistance is impaired. Tend.
On the other hand, when the film thickness is large, the plating layer tends to peel off easily due to the stress of the film. The formation of the gold plating layer and the platinum plating layer is carried out by a conventional means, that is, by plating the outer peripheral surface of the power supply terminal using an aqueous solution of gold chloride or platinum chloride as a plating solution.

In the first to third aspects of the present invention, the ceramic sintered body having the resistance heating element embedded and built therein is generally obtained by the following means. For example, an aluminum nitride-based sintered body is granulated from a slurry obtained by adding and mixing a sintering aid and a binder to aluminum nitride powder having an average particle size of about 0.01 to 5 μm, and forming the granules into a desired shape and size. After thermal degreasing of organic components,
It is manufactured by sintering in a high temperature inert atmosphere of 1800 ° C. or higher.

The sintering aid is exemplified by yttrium oxide and the like, and the binder is exemplified by polyvinyl butyral. Prior to high-temperature sintering, it is desirable to provide grooves for disposing and embedding a resistance heating element on one main surface of the molded body in advance.

In addition, when the resistance heating element is embedded in the aluminum nitride-based base material, the resistance heating element is positioned and arranged between the facing surfaces of the aluminum nitride-based members to be combined. A bonding agent such as an aluminum nitride-yttrium oxide-lithium oxide paste or the like is printed or applied to form a bonding layer.
It is performed by heating at a temperature of about 0 to 1750 ° C.

[0021]

An embodiment will be described below with reference to FIGS. 1, 2 (a), 2 (b) and 3. FIG.

First, in order to temporarily confirm the effect of imparting acid resistance, a plurality of tungsten rod-shaped power supply terminals having a diameter of 4 mm and a length of 230 mm were prepared. On the other hand, a gold plating solution as an aqueous solution of gold chloride and a platinum plating solution as an aqueous solution of platinum chloride were prepared. One of the rod-shaped power supply terminals is immersed and arranged in a gold plating solution, a plating voltage is applied between the electrode and a counter electrode, and a gold plating process is performed for 60 minutes. A power supply terminal (sample 1) is manufactured. FIG. 1 shows a cross-sectional structure of a manufactured power supply terminal 1. In FIG. 1, reference numeral 1a denotes a rod-shaped power supply terminal main body made of tungsten, and 1b denotes a gold plating layer (A
u).

Further, according to the conditions of the above embodiment, a power supply terminal (sample 2) whose outer peripheral surface is covered with a gold (Au) plating layer 1b having a thickness of 20 μm, and FIG. Gold (Au) with a 25 μm-thick outer peripheral surface showing the structure
Plating layer 1b ₁ - platinum (Pt) plating layer 1b ₂ coated with the power supply terminal (Sample 3), the outer peripheral surface is 50 [mu] m (Sample 4), as shown a cross-sectional structure in FIG. 2 (b) or 60
μm (sample 5) gold plating layer 1b ₁ -platinum plating layer 1b
₂ - gold plating layer 1b 1 _- each platinum plating layer 1b coated powered terminal ₂ was produced. Also, for comparison,
A power supply terminal (comparative example) in which the coating of the plating layer 1b on the outer peripheral surface was omitted was produced.

Next, each power supply terminal having the above configuration is connected to 800
Table 1 shows the results of examining the oxidation resistance based on the change in weight before and after the treatment by leaving the sample in air at 100 ° C. for 100 hours.

[0025]

[Table 1]

As can be seen from Table 1, the rate of change in weight increase due to oxidation is 1/20 or less in the case of the power supply terminal according to each sample (Example) as compared with the case of the power supply terminal of the comparative example. The thinner the thickness of the coating plating layer, the lower the tendency was, and it was confirmed that the coating plating layer exhibited remarkably excellent oxidation resistance.

Next, an embodiment of a planar ceramic heater incorporating the power supply terminal 1 whose outer peripheral surface is covered with a plating layer will be described. FIG. 3 is an enlarged cross-sectional view showing a configuration of a main part of the planar ceramic heater.
6 mm thick aluminum nitride-based base material having a main surface serving as a heat dissipation / heating surface.
And a 6 mm-thick aluminum nitride-based base material layer 2b that leads out the power supply terminal 1 to the other main surface side by hot pressing via a bonding agent layer (not shown) and is integrally formed. Reference numeral 3 denotes a resistance heating element made of a tungsten wire having a diameter of 0.4 mm.
The power supply terminal 1 is embedded between the terminals a and 2b and connected to the connected terminal portion.

That is, in the configuration of this planar ceramic heater, the outer peripheral surface of the power supply terminal 1, which is at least extracted from the aluminum nitride base material layer 2b and exposed to the air, has a gold or platinum plating layer 1b. It is covered with.

In the configuration of the planar ceramic heater, at least the power supply terminal derived from the aluminum nitride base material layer 2b and having the outer peripheral surface of the power supply terminal body 1a exposed to the atmosphere covered with a gold plating layer 1b or the like. There are five types, each using the supply terminal 1, and for comparison,
A planar ceramic heater using the power supply terminal according to the comparative example was also manufactured.

Next, each of the planar ceramic heaters having the above-described configuration is separately positioned and mounted in the processing chamber of the semiconductor manufacturing apparatus, the processing chamber is set to a reduced pressure Ar-based atmosphere, and power is supplied to the planar ceramic heater. , Process chamber temperature to 7
It was set to be kept at 50 ° C. In the positioning mounting of the planar ceramic heater, a part of the power supply terminal 1 is led out of the processing chamber and is exposed to the high-temperature atmosphere.

In the heating operation of the above-mentioned planar ceramic heater, in the case of each planar ceramic heater according to the embodiment, the property change due to oxidation of the power supply terminal 1 area which is led out of the processing chamber and exposed to the atmosphere is prevented. Therefore, a stable power supply is performed as compared with the comparative example. In other words, stable heat dissipation in the planar ceramic heater
Heat generation is easily and constantly ensured.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the shape and material of the resistance heating element, the material of the input power terminal, or the material, shape and dimensions of the ceramic base material can be selected and set according to the application. In addition, the present invention can be applied to configurations such as an electrostatic chuck and a susceptor with a built-in electrode.

[0033]

According to the first to third aspects of the present invention, the portion of the power supply terminal exposed to the high-temperature atmosphere is covered with a thin plating layer having excellent chemical stability even in the high-temperature atmosphere. Therefore, performance degradation due to oxidation of the power supply terminal is eliminated, and a highly durable planar ceramic heater having stable power supply capability is provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a configuration of a main part of a power supply terminal according to an embodiment.

FIGS. 2A and 2B are cross-sectional views illustrating an example of a configuration of a main part of a power supply terminal according to another embodiment.

FIG. 3 is a cross-sectional view illustrating a configuration of a main part of the planar ceramic heater according to the embodiment.

[Explanation of symbols]

1 ...... the power supply terminal 1a ...... power supply terminal body _1b, 1b 1, 1b ₂ ...... plating layer 2 ...... aluminum nitride substrate 3 ...... resistance heating element

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[Procedure amendment]

[Submission Date] April 18, 2001 (2001.4.1
8)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuhiro Fujita 30 Soya, Hadano-shi, Kanagawa Prefecture Toshiba Ceramics Co., Ltd. (72) Inventor Noriaki Kashiwa 30 Soya, Hadano-shi, Kanagawa Toshiba Ceramics Co., Ltd. Inventor Akira Miyazaki 30 Soya, Hadano-shi, Kanagawa F-term in Toshiba Ceramics Co., Ltd. Development Research Laboratory (reference) GA04

Claims (3)

[Claims] 1. A planar ceramic base having one main surface serving as a heat dissipation / heating surface, a resistance heating element embedded and arranged in the ceramic base, one end connected to the resistance heating element, and the other end connected to the resistance heating element. A planar ceramic heater having a power supply terminal led out on the other main surface side of the ceramic base material, wherein at least the outer peripheral surface of the power supply terminal exposed to the high-temperature atmosphere is made of gold, platinum or gold and platinum. A planar ceramic heater characterized by being coated with layered plating. 2. The planar ceramic heater according to claim 1, wherein the plating layer to be coated is formed in a multilayer structure in the order of a gold plating layer and a platinum plating layer. 3. The plating layer to be coated has a thickness of 5 to 70 μm.
The planar ceramic heater according to claim 1 or 2, wherein: