JPH01207927A - Thermal treatment apparatus - Google Patents

Abstract

PURPOSE:To avoid-air-back diffusion by a method wherein a door provided at one of the openings of a core tube is composed of a double-door and an exhaust tube us connected to a tube wall between the two doors. CONSTITUTION:A quartz tube 1 is used as a core tube. An inner door 7 is provided inside an outer door 6 which closes an opening at the end of the quartz tube 1 opposite to the end to which a gas introducing tube 4 is connected. The two doors are linked with a quartz bar 8 and an exhaust tube 5 is connected to the tube wall between the two doors 6 and 7. A small gap is provided between the inner door 7 and the quartz tube 1. Even if the outside atmosphere penetrates through the gap of the outer door 6, it is discharged through the exhaust tube 5 with reactive gas and does not enter the space inside the inner door 7 and does not reach around heated objects. With this constitution, the inner door 7 serves as a barrier against the outside atmosphere and air-back diffusion can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat treatment apparatus used when heating a silicon plate in a gas for oxidation or impurity diffusion.

[Conventional technology]

To oxidize and diffuse a silicon plate, it is necessary to heat the silicon plate in a gas. This heat treatment is performed in an electric furnace in a quartz tube through which gas is passed. When storing a silicon plate in a quartz tube, if you slide the support stand with the silicon plate upright onto the quartz tube surface, there is a risk that dust adhering to the tube surface will fly up and adhere to the silicon plate surface. This was done by placing it on a fork and inserting it through one opening of the quartz tube, a so-called soft landing.

[Problem to be solved by the invention]

Although not shown, FIG. 2 shows a state in which a quartz support 3 on which a silicon plate 2 is erected is inserted by soft landing into a quartz tube 1 as a furnace core tube wrapped with a heating wire. The quartz tube 1 has a gas introduction tube 4 at one end. Exhaust pipe 5 near the other end
is attached, and the opening for inserting the support stand 3 on the exhaust pipe 5 side is closed by a door 6. However, it is difficult to completely block off the large entrance for inserting the fork with the door 6, so outside air enters through the small gap, which causes air back day that adversely affects the silicon plate 2 during the heat treatment process of oxidation and diffusion. A fusion phenomenon occurs.

An object of the present invention is to solve the above-mentioned problems and provide a heat treatment apparatus in which air bank diffusion does not occur.

[Means to solve the problem]

In order to solve the above problems, the device of the present invention has two parallel doors connected to each other that close the opening at the other end of the reactor tube, which has a gas inlet at one end. It is assumed that there is a slight gap between the door and the wall of the core tube, and an exhaust port is opened in the wall of the core tube between both doors.

[Effect]

The gas introduced from the inlet passes around the heated object such as a silicon plate housed inside by soft landing, and enters the space of the outer door through the gap between the inner door and the tube wall of the core tube. Exit outside through the exhaust port. Even if outside air enters through the gap in the outer door, it is exhausted along with the gas from the exhaust port and does not enter the internal space through the inner door, so it does not reach the surroundings of the heated object.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and parts common to those in FIG. 2 are given the same reference numerals. As is clear from the figure, an inner door 7 is added inside the door 6 that closes the opening at the opposite end of the quartz tube 1 from the gas introduction pipe 4, and the two doors are connected by a quartz rod 8. The exhaust pipe 5 is connected to the pipe wall between the doors 6 and 7. There is a slight gap between the inner door 7 and the quartz tube 1, and after inserting the support base 3 into the quartz tube by soft landing, the outer door 6 is inserted without the inner door 7 coming into contact with the wall of the quartz tube 1. This allows the opening of the quartz tube to be closed. In the case of oxidation, a carrier gas containing oxygen or water vapor, and in the case of diffusion, impurities to be diffused is introduced from the introduction pipe 4. The remaining gas that has oxidized and diffused the silicon plate 2 on the support base 3 comes out from the gap between the inner door 7 and the wall of the quartz tube 1 and is exhausted from the exhaust pipe 5. On the other hand, outside air that enters the space between the outer door 6 and the inner door 7 through the unavoidable gap that occurs between the outer door 6 and the quartz tube 1 is also exhausted from the exhaust pipe 5, so that it cannot enter the space through the inner door 7. do not have.

〔Effect of the invention〕

According to the present invention, by doubling the door at one opening of the reactor core tube and providing an exhaust port in the tube wall between them, even if outside air may enter through the outer door, the reaction inside the reactor core tube can be prevented. The inner door acts as a barrier to the outside air and prevents air back diffusion, and the material to be heated can be inserted without contacting the core tube wall with a soft landing. A large opening can be provided in the reactor core tube, and it can be used extremely effectively particularly for oxidation or diffusion heat treatment of large-diameter silicon plates.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heat treatment apparatus according to an embodiment of the present invention, and FIG.
The figure is a sectional view of a conventional device.

Claims (1)

[Claims] (1) It has two parallel doors connected to each other that close the opening at the other end of the furnace tube with a gas inlet at one end, and the inner door has a small gap between it and the wall of the furnace tube. A heat treatment device characterized by having a gap and having an exhaust port opened in the tube wall of the furnace tube between both doors.