JPH10273782A - Substrate heating device in cvd device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow this device to withstand a high temp. oxidizing atmosphere and to remarkably increase the substrate heating temp. by a simple constitution by interposing a washer made of iridium between a heater made of silicon carbide and an electrode made of silicon carbide and fixing the heater and electrode by a clamp made of silicon carbide. SOLUTION: An electrode 12 and a heater 13 are respectively formed of electroconductive silicon carbide withstanding a high temp. oxidizing atmosphere. A female screw 12a is formed at the upper end of the electrode 12, and a bolthole 13a is formed at the prescribed position of the heater 13. In a state in which a washer 17 made of iridium is interposed between the electrode 12 and the heater 13, a bolt 18 made of electroconductive silicon carbide is clamped to fix, by which the substrate heating device is formed. By making the washer 17 of iridium, the electric resistance between the electrode 12 and the heater 13 is almost eliminated, in the heater 13, heat can efficiently be generated, and further, the damage to the washer 17 in a high temp. oxidizing atmosphere can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate heating apparatus for a CVD apparatus, and more particularly, to a method for introducing a source gas containing an oxidizing substance such as oxygen onto a substrate which is heated to a predetermined temperature. The present invention relates to a fixing structure of a heater for heating a substrate in a CVD apparatus for forming an oxide thin film.

[0002]

2. Description of the Related Art As shown in FIG. 3, a CVD apparatus heats a substrate 3 to a predetermined temperature by a heater 2 installed in a reaction chamber 1 and also feeds the reaction chamber 1 through a path 4. A gaseous raw material is introduced therein, and the raw material is reacted on the substrate 3 to form thin films of various compositions.

In such a CVD apparatus, Y1 (S
rBi ₂ Ti ₂ O ₉ ), PZT (Pb (Zr, Ti) O
₃ ), ferroelectrics such as Bi ₄ Ti ₃ O ₁₂ and Bi-Sr-
When forming a superconductor oxide thin film such as a Ca-Cu-O-based or Y-Ba-Cu-O-based thin film, the reaction chamber becomes a high-temperature oxidizing atmosphere. It uses a silicon carbide heater that can withstand the target.

In this case, between the heater made of silicon carbide and the electrode made of silicon carbide, a washer made of molybdenum or platinum is interposed in order to conduct electricity between the two. However, in an actual high-temperature oxidizing atmosphere, a heater or electrode made of silicon carbide reacts, or cracks occur due to oxidation of the electrode, thereby causing electric discharge. Therefore, the heating temperature of the substrate could not be sufficiently increased. For this reason, it was difficult to obtain a good film-forming substrate, and reproducibility was not sufficient.

For example, with a conventional heater, the substrate temperature can only be set at about 450 to 550 ° C., so that the crystallization temperature of the film to be formed cannot be exceeded. After performing the film formation process at ℃
It was necessary to take out the substrate from the reaction chamber, heat it to 600 ° C. or more in another annealing furnace, and perform heat treatment for crystallization.

On the other hand, a molybdenum or platinum washer is interposed between the heater and the electrode, and a reaction between the heater and the electrode is prevented by surrounding the heater portion with an inert gas atmosphere. By adopting a structure that dissipates heat to the low-temperature section to prevent the temperature of the electrode section from becoming too high, various measures have been taken to increase the heating temperature of the substrate. Has become complicated, which has had a major effect on the cost of the apparatus.

Accordingly, an object of the present invention is to provide a substrate heating apparatus capable of withstanding a high-temperature oxidizing atmosphere with a simple structure and capable of greatly increasing the substrate heating temperature.

[0008]

In order to achieve the above object, a substrate heating apparatus in a CVD apparatus according to the present invention has an iridium washer interposed between a heater made of silicon carbide and an electrode made of silicon carbide. In this state, the heater and the electrode are fixed by a fastening tool made of silicon carbide.

Here, it is preferable that the heater, the electrode, and the fastener are all formed of silicon carbide having good conductivity. It is necessary to preheat the electrode section by providing a heater. An example of silicon carbide having good conductivity is conductive silicon carbide described in, for example, Japanese Patent Application Laid-Open No. 2-204363. Since silicon carbide has high purity, it contaminates the reaction chamber. It is particularly preferable because it does not occur.

[0010]

FIG. 1 is a sectional view showing an embodiment of a substrate heating apparatus according to the present invention, and FIG. 2 is an exploded sectional view of a main part. The substrate heating device 10 supports a heater 13 by an electrode 12 erected on a quartz base 11 and covers the heater 13 with a quartz cover 15 having a substrate mounting portion 14. Heater 13 and base 1
A reflector 16 made of stainless steel is provided between the reflector 1 and the reflector 1.

The electrode 12 and the heater 13 are each made of conductive silicon carbide which can withstand a high-temperature oxidizing atmosphere, and as shown in FIG.
A female screw 12a is formed at an upper end of the heater 13, and a bolt hole 13a is formed at a predetermined position of the heater 13. The electrode 12 and the heater 13 are fixed by tightening a conductive silicon carbide bolt 18 with an iridium washer 17 interposed between the electrode 12 and the heater 13.

As described above, since the washer 17 interposed between the electrode 12 and the heater 13 is made of iridium, the electric resistance between the electrode 12 and the heater 13 can be almost eliminated, and the efficiency of the heater 13 can be reduced. Heat can be generated well, and the washer 17 can be prevented from being worn in a high-temperature oxidizing atmosphere.

As a result, the heat generation temperature of the heater 13 can be made much higher than in the prior art, and the substrate can be heated to a sufficiently high temperature state, for example, to about 750 ° C., so that the crystallization temperature becomes 600 to 700 ° C. In the case of producing a crystallized film of a degree, a crystallized film can be obtained by a single film forming operation in a CVD apparatus, and the film forming state is improved, and the reproducibility is improved.

Further, since the washer 17 does not wear out even in a high-temperature oxidizing atmosphere, there is no need to make the heater portion an inert gas atmosphere, so that the size of the CVD apparatus can be reduced.

If the purity of iridium used for the washer 17 is low, the iridium is hardened, the contact resistance (electrical resistance) is increased, and the heat resistance in an oxidizing atmosphere is also reduced. It is preferable that the amount of iron present as an impurity therein is 100 ppm or less.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A heater made of conductive silicon carbide having a predetermined shape,
Prepare an electrode and a bolt and fix them without a washer, use a molybdenum washer, use a platinum washer, and use four types of heaters when using an iridium washer Was prepared. Note that molybdenum and platinum have been conventionally used as materials relatively resistant to a high-temperature oxidizing atmosphere.

Using the heaters (1) to (B),
a _x , Sr _1-x ) TiO ₃ (ferroelectric: barium strontium titanate) thin film (crystallization temperature around 600 ° C)
An experiment was performed to form. The source gas includes Ba (DP
M) ₂ / THF, Sr (DPM) ₂ / THF, Ti (O
Pr) ₂ / THF was used (DPM represents dipivaloylmethane, THF represents tetrahydrofuran), and argon was used as a carrier gas. 2.5SLM total gas flow
The film forming pressure was 5 Torr and the oxygen partial pressure was 50%.

As a result, in the case where the heater and the electrode are fixed without a washer (), electric power is not supplied from the electrode to the heater, and a discharge is generated, so that the substrate cannot be heated and the film is formed. I couldn't do that. When a molybdenum washer was used (), the substrate could be heated only to 450 ° C., and the obtained film was in an amorphous state and had a nonuniform film thickness. In the case of using a washer made of platinum (), although the substrate could be heated to 530 ° C., the obtained film was similarly in an amorphous state, and the film thickness varied. Furthermore, oxides and reaction products were attached to the outer peripheral surfaces of both molybdenum and platinum washers after the experiment, and the electric resistance of the entire heater also increased after the experiment. When the heater was disassembled after the experiment and the weight of the washer was measured, the weight of the molybdenum washer was sharply reduced as compared to before the experiment, and the weight of the platinum washer was also reduced.

On the other hand, when an iridium washer was used (), the substrate could be heated to 750 ° C., and a crystallized film having a uniform thickness and a good state could be obtained. At this time, the temperature of the electrode rose to 840 ° C., but no change was observed in the iridium washer after the experiment, the weight was almost the same, and the electric resistance of the entire heater did not increase. Further, the experiment was repeated, and almost the same result was obtained, and the reproducibility was satisfactory.

[0020]

As described above, according to the substrate heating apparatus of the present invention, since the heating temperature of the substrate can be increased, a crystallized film can be easily produced, and the reproducibility can be improved. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a substrate heating apparatus according to the present invention.

FIG. 2 is an exploded sectional view of a main part.

FIG. 3 is an explanatory diagram of a main part of a CVD apparatus.

[Explanation of symbols]

10: substrate heating device, 11: base, 12: electrode, 13
... heater, 14 ... substrate mounting part, 15 ... cover, 16 ...
Reflector, 17 ... Iridium washer, 18
…bolt

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiko Murakami 585 Tomicho, Funabashi-shi, Chiba Pref.Sumitomo Osaka Cement Co., Ltd.

Claims (1)

[Claims] 1. A substrate heating apparatus used in a CVD apparatus for forming an oxide thin film on a substrate in a high-temperature oxidizing atmosphere,
Between the heater made of silicon carbide and the electrode made of silicon carbide, the heater and the electrode were fixed with a fastener made of silicon carbide in a state where a washer made of iridium was interposed in the CVD apparatus. Substrate heating device.