JPS6216519A - Heat-treating method for heat equalizing tube of semiconductor diffusion furnace - Google Patents

Abstract

PURPOSE:To form an oxide film uniformly on the inner surface of a heat-equalizing tube as well as to perform the cleaning of the inner surface of the heat-equalizing tube uniformly by a method wherein the heat-equalizing tube and a gas-introducing cap are airtightly connected to a high-temperature furnace, gas is introduced from a gas introducing cap, the inner surface of the heat-equalizing tube is cleaned or an oxide film is formed thereon. CONSTITUTION:A heat equalizing tube is constructed in such a manner that the airtightness of the internal part of the heat-equalizing tube can be maintained by the pushing spring 6 provided at the handle part of a gas-introducing cap 4a and a gas exhausting cap 4b which are provided outside a furnace. The quality of material of the gas-introducing cap 4a and the gas-exhausting cap 4b is selected from the high-purity and airtight material which can resist the temperature of 1,200 deg.C or above. As the high-purity packing material 5 can resist the high temperature of 1,200 deg.C or above, high-purity quartz, wool or the alumina fiber and the like whereon a refining treatment is performed are considered suitable. O2 gas or the mixed gas and the like of O2 gas and HCl gas is introduced from the gas introducing hole provided at the edge of the handle part of the gas introducing cap 4a, and the furnace is heated up to 1,200 deg.C or above using a heater 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of heat treating the inner surface of a soaking tube used in a semiconductor diffusion furnace using high-temperature gas.

[Conventional technology]

Generally, this type of soaking tube is used as a member for uniformly heating a woofer, which is a semiconductor material, during semiconductor manufacturing. An important characteristic of the soaking tube is that it is not only made of high-purity material with low volatilization of impurities, but also that it is gas-impermeable to prevent the wafer inside the tube from being contaminated by impurities volatilized from the furnace wall during heating. sexuality is required.

In order to satisfy the above characteristics, for example, there is a soaking tube made of recrystallized silicon carbide whose pores are impregnated with silicon. The recent development of the semiconductor industry is remarkable, and as semiconductors become more highly integrated,
There is an increasing demand for prevention of impurity volatilization from soaking tubes. 1200-1300 as a method of preventing impurity volatilization
A heat treatment method is carried out in which a high-purity oxide film is formed on the inner surface of the soaking tube with O2 gas or the inner surface of the soaking tube is cleaned with HCl gas or the like at a high temperature of C.

Conventionally, as shown in FIG. 2, the above-mentioned heat treatment method connects a high-purity quartz gas inlet cap 1a and a gas outlet cap 1b to both ends of a soaking tube 2, and connects the opening of the gas inlet cap 1a. The structure was such that 02 gas and HCl gas were introduced through the gas discharge cap 1b and discharged from the gas discharge cap 1b. Furthermore, the soaking tube 2 is heated to 1200 m by the heating heater 3.
It was supposed to be heated above C.

[Problem that the invention seeks to solve]

In the above-mentioned heat treatment method, when a soaking tube is heat-treated by introducing a stone gas, the temperature cannot be raised above 1200 C in the vicinity of the connection between the soaking tube and the cap. Therefore, the above connection part should be installed outside the furnace, or
By installing it in a temperature range of 0 C or lower, a decrease in airtightness due to softening of the stone cap was prevented.

As mentioned above, since the heat treatment temperature was different between the center of the soaking tube and the connection areas at both ends, the formation of an oxide film by 02 gas on the inner surface of the soaking tube and the cleaning of the inner surface by HCl gas etc. were uneven. However, sufficient purity could not be achieved.

The present invention provides a method for heat treating a soaking tube that eliminates the above-mentioned drawbacks.

[Means for solving problems]

That is, the present invention provides a heat treatment method for a soaking tube used in a semiconductor diffusion furnace, in which the soaking tube and the gas introduction cap are heated at 120° C.
Connect airtightly through a high-purity packing material directly in a high-temperature furnace at 0 C or higher, and feed HCl gas, 02 gas, etc. from the gas introduction cap to clean the inner surface of the soaking tube or remove the oxide film. It is characterized by forming.

〔composition〕

Next, the present invention will be explained with reference to FIG. In FIG. 1, a soaking tube 2 for a semiconductor diffusion furnace is installed in the furnace, and the soaking tube 2
A gas introduction cap 4a is connected to one end of the gas inlet, and a gas discharge cap 4b is connected to the other end thereof through a high-purity packing material 5, respectively. The handle of the gas inlet cap 4a and the gas exhaust cap 4b installed outside the furnace is configured to maintain airtightness inside the soaking tube by means of a push spring 6.

The above airtightness is achieved when the spring pressure is 15V4 and the furnace temperature is 130V.
At 0 C:, the pressure inside the tube can reach a positive pressure of 1000100O. The materials for the gas introduction cap 4a and the gas discharge cap 4b are selected from those that can withstand high temperatures of 1200° C. or higher, are airtight, and have high purity.

Preferably, it is made of recrystallized silicon carbide impregnated with silicon, which is the same material as the soaking tube for semiconductor diffusion furnaces. Furthermore, since the high purity packing material 5 according to the present invention is required to withstand high temperatures of 1200° C. or higher and to be highly pure, it is preferably made of high purity quartz wool or alumina fibers that have been purified with HCl gas.

After creating such a structure, 02 gas or a mixed gas of 02 gas and HCl gas, etc. is introduced from the gas introduction hole provided at the end of the handle of the gas introduction cap 4a, and the inside of the furnace is heated to 1200° C. or higher using the heater 3. By doing so, heat treatment can be performed on the inner surface of the soaking tube to form an oxide film using O2 gas and to clean the inner surface using HCl gas or the like.

The present invention will be explained by examples.

〔Example〕

As shown in FIG. 1, a soaking tube for a semiconductor diffusion furnace made of recrystallized silicon carbide was installed in a heat treatment furnace.

The soaking tube has an outer diameter of 5L% and an inner diameter of ψ100mm.
The interior of the oven was heated to 1300° C., and 541 n×Qi of 02 gas was flowed from the gas inlet for 50 minutes to form an oxide film on the inner surface of the soaking tube. A 2 μm thick oxide film was observed both in the center of the heat soaking tube and in the vicinity of the connection with the cap. In this example, quartz wool was used as the packing material, and recrystallized silicon carbide, which is the same material as the soaking tube, was used as the cap.

For comparison, an oxide film was formed using the conventional installation method shown in FIG. 2 under the same conditions as described above.

In this comparative example, the cap is made of stone material,
The connection between the soaking tube and the cap was heated to about 1000°C. In the conventional case, the central part of the soaking tube was measured to have a thickness of 2 μm, the same as in the embodiment according to the present invention, but the thickness decreased as it approached the connection part, and the thickness was 0.7 μm near the connection part. Ta.

That is, according to the present invention, a uniform oxide film was formed on the inner surface of the soaking tube for a semiconductor diffusion furnace.

〔Effect of the invention〕

As described above, the present invention makes it possible to heat the entire soaking tube for a semiconductor diffusion furnace at the same temperature, and to
Because it is possible to uniformly form an oxide film using two gases and to clean the inner surface using HCl gas or the like, it can be said to be the last method of heat treatment for soaking tubes used in diffusion furnaces for semiconductor manufacturing.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a method of heat treating a soaking tube for a semiconductor diffusion furnace according to the present invention. FIG. 2 is a schematic cross-sectional view showing a conventional heat treatment method for a soaking tube for a semiconductor diffusion furnace. 1a...Quartz gas introduction cap 1b...
... Quartz discharge cap 2 ... Soaking tube for semiconductor diffusion furnace 3 ... Heater 4a
...Gas introduction cap 4b...
・Yap during gas discharge 5...Packing material 6...Press spring patent applicant Tokai Konetsu Kogyo Co., Ltd. Figure 1 Figure 2. figure

Claims (1)

[Claims] In a heat treatment method for a soaking tube used in a semiconductor diffusion furnace, the soaking tube, a gas inlet cap, and a gas discharge cap are connected airtight directly through a high-purity packing material in a high-temperature furnace of 1200°C or higher, and the gas is introduced. H from the cap
A heat treatment method for a soaking tube for a semiconductor diffusion furnace, the method comprising feeding Cl gas, O_2 gas, etc. to clean the inner surface of the soaking tube or forming an oxide film.