JPH0845651A - Multi-layer ceramic heater - Google Patents

Abstract

PURPOSE:To heat an object effectively and attain a high temp. while the electric power is saved, by furnishing a low emission rate layer on the surface opposite the heating surface. CONSTITUTION:A double-layer ceramic heater is prepared by laminating insulative layer and conductive layer, wherein the insulative layer is made of nitrides of silicon, aluminum, boron or oxides such as alumina, quartz, etc., while the conductive layer is made of a high melting point metal such as W, Pt, Ta or conductive ceramics such as SiC, carbon, etc. A low emission rate layer having a rate of emission below 0.2 is provided on the surface opposite the heating surface. The low emission rate layer is made of a high melting point metal such as W, Ta, Mo, Pt using such method as sputtering, EB evaporation, CVD, etc. Thereby the object can be heated effectively, and a high temp. be attained while the electric power is saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is useful for heating a substrate or wafer when forming a thin film by a chemical vapor deposition method or a sputtering method, since it is capable of performing uniform soaking heating on a multilayer ceramic heater. The present invention relates to a multilayer ceramic heater.

[0002]

2. Description of the Related Art As a heating reaction of a wafer in molecular beam epitaxy, CVD, sputtering, etc. in a semiconductor product manufacturing process, pyrolytic boron nitride (P-BN) is used.
It is said that it is effective to use a composite ceramic heater of graphite and pyrolithic graphite (PG).
3-241921), this product is easier to install than conventional tantalum wire heaters and has no troubles such as thermal deformation, disconnection and short circuit, and is easy to use. Is also easy to obtain.

[0003]

However, in recent years, there has been a demand for a device having a large diameter and a high operating temperature, which is accompanied by an increase in power consumption required for heating and heat insulation. There is a demand for simplification of the equipment required for. Therefore, generally, in heating a wafer in a semiconductor process, the heater is used for heating only one side, and the other side is covered with a heater shield in which high melting point metal thin films such as Mo and W are stacked so as not to lose heat. Although the thing used is this, the energy required for heating is almost determined by the performance of its heat shield, and if it is strengthened it becomes an energy saving type heater, but to strengthen this heat shield, there is space for it It has the disadvantages of being necessary, costly and complicating the device.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a multi-layer ceramic heater which solves the above disadvantages and drawbacks, and it relates to a multi-layer planar ceramic heater having an insulating layer and a conductive layer laminated thereon. A low emissivity layer having an emissivity of 0.2 or less is provided on the surface opposite to the heating surface.

That is, the present inventors have conducted various studies to develop a multi-layer ceramic heater which satisfies the requirements of large diameter and high temperature, saves energy, and can simplify the heat insulating structure. In order to save energy, it was found that heat loss can be reduced by providing a layer with low emissivity on the surface without heating, and this low emissivity layer has an emissivity of 0.2 on the surface opposite to the heating surface. The present invention has been completed by confirming that the following is required. This will be described in more detail below.

[0006]

The present invention relates to a multi-layer ceramic heater, which is a multi-layer planar ceramic heater having an insulating layer and a conductive layer laminated as described above, and radiates to a surface opposite to the heating surface. The low emissivity layer having a coefficient of 0.2 or less is provided. Since the heat loss can be reduced by providing the low emissivity layer, this heater can be an energy saving type. The advantage is given.

As shown in FIG. 3, the multi-layer ceramic heater is formed by laminating an insulating layer and a conductive layer. The insulating layer is made of a nitride such as silicon nitride, aluminum nitride or boron nitride, or alumina, The conductive layer may be made of an oxide such as quartz, and the conductive layer may be made of a refractory metal such as W, Pt, or Ta, or a conductive ceramic such as SiC or carbon.

However, the heat conduction of this material is dominated by radiation particularly in a vacuum in processes such as sputtering, CVD deposition, and MBE at a high temperature of 600 ° C. or higher, which influences the emissivity (ε) of the material surface. Therefore, if the emissivity (ε) of the surface to be heated is increased and the emissivity (ε) of the opposite surface is decreased, the object to be heated can be efficiently heated, and heat will be generated in other directions. It has been found that the object can be heated to a high temperature with low power consumption if it is prevented from being transmitted. Therefore, in the multilayer ceramic heater of the present invention, a low emissivity layer is provided on the surface opposite to the heating surface. Is provided. One example is shown in FIG.

[0009] the heat transfer amount Q Hatsugi formula (1) of the radiation from the low emissivity layer _{Q = 4.88A 1 ((T 1} /100) 4 - (T 2/100) 4) / ((1 / ε
₁ ) + (1 / ε ₂ ) -1) A ₁ : heater area, T ₁ : heater temperature T ₂ : heated object temperature ε ₁ : heater emissivity ε ₂ : calculated by the heated object emissivity, This radiation is reduced by reducing the emissivity (ε ₁ ) of the heated object, the heating source, and thus this heat loss is reduced. Therefore, in this multi-layer ceramic heater, if a layer having a small emissivity (ε ₁ ) is provided on the side not to be heated, the radiant heat loss is reduced on that side, so this heater is an energy-saving type. , This emissivity (ε ₁ ) is 0.2
If it is larger than this, the amount of heat transfer will be large, so 0.2 or less is required.

The low-emissivity layer may be formed by providing a refractory metal such as W, Ta, Mo, or Pt by a method such as a sputtering method, an EB vapor deposition method, a CVD method, or the like. This makes it possible to make this heater most suitable for energy-saving type whose surface emissivity is 0.2 or less. In addition, according to this multilayer ceramic heater, power consumption can be reduced and heat shield can be reduced, and thereby the apparatus itself can be made compact. In addition, this product has the advantage that it can fully exert its effects in heating large area wafers and in high temperature processes of 1,000 ° C or higher.

[0011]

EXAMPLES Next, examples of the present invention will be given. Example A comb-shaped heater having a thickness of 50 μm was formed on one surface of an Al ₂ O ₃ plate having a thickness of 5 mm and a diameter of 100 mm by W paste.
On the opposite surface, three types were prepared: one that does nothing, one that Pt is vapor-deposited to a thickness of 10 μm by an EB gun, and one that is Pt surface mirror-finished by polishing.

The emissivity of the back surface of this heater is as shown in Table 1. The electric power required to heat this heater to 500 ° C. and 1,000 ° C. was measured, and the results shown in FIG. 1 were obtained. It was confirmed that the multi-layer ceramic heater of the present invention can achieve high temperature with less electric power.

[0013]

[Table 1]

[0014]

The present invention relates to a multi-layer ceramic heater, which is a multi-layer planar ceramic heater having an insulating layer and a conductive layer laminated as described above.
A low emissivity layer with an emissivity of 0.2 or less is provided on the surface opposite to the heating surface.
This has the advantage that the object to be heated can be efficiently heated and can be heated to a high temperature with low power consumption.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between electric power (W) and stable temperature (° C.) of a multilayer ceramic heater according to an example of the present invention.

FIG. 2 shows a cross-sectional view of a multilayer ceramic heater of the present invention.

FIG. 3 is a cross-sectional view of a conventional multilayer ceramic heater.

[Explanation of symbols]

 1 ... Substrate 2 ... Conductive layer 3 ... Low emission layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Kawada 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd. Precision Materials Research Laboratory

Claims (3)

[Claims] 1. A multi-layer planar ceramic heater comprising a laminate of an insulating layer and a conductive layer, wherein a low emissivity layer having an emissivity of 0.2 or less is provided on a surface opposite to a heating surface thereof. And multi-layer ceramic heater. 2. The insulating layer is made of a nitride such as silicon nitride, aluminum nitride, or boron nitride, or an oxide such as alumina or quartz, and the conductive layer is a refractory metal such as W, Pt, or Ta, or SiC. , E.g., conductive ceramics such as carbon, and the low emissivity layer is made of W, Pt, T
The multilayer ceramic heater according to claim 1, which is made of a high-purity metal such as a. 3. The multi-layer ceramic heater according to claim 1, wherein the insulating layer is boron nitride formed by a CVD method, and the conductive layer and the low emissivity layer are formed by CVD, a screen pattern or the like. .