JPS6348838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of producing a CVD film on a silicon wafer using a diffusion furnace type CVD apparatus.

The diffusion furnace type used in this invention is a device commonly called a low pressure CVD device or LPCVD, in which a vacuum pump is placed on the exhaust side of the diffusion furnace.
It is a CVD device. Silicon dioxide films, nitride films, polysilicon films, etc. are produced using this diffusion furnace type low pressure CVD equipment, but this equipment in particular
The combination of SiH ₄ and O ₂ is effective when used to produce silicon dioxide films. below,
An example of a silicon dioxide production process using SiH ₄ and O ₂ will be explained.

The apparatus shown in FIG. 1 has conventionally been used to produce this type of CVD film. In the figure, 1 is a reaction tube, 2 is a boat, 3 is a silicon wafer, 4 is a gas inlet, 5 is a gas outlet, 6 is a heater, 7 is an inlet side fitting, and 8 is an outlet side fitting. Next, using the conventional equipment shown in Figure 1,
The method for producing CVD films will be explained. First, the silicon wafer 3 is placed on the boat 2 and inserted into the reaction tube 1. Next, SiH ₄ and O ₂ gases are simultaneously introduced from the inlet 4 to the silicon wafer 3 and the reaction tube 1.
It passes through the gap with the inner peripheral surface and is exhausted from the outlet 5. At this time, a CVD film (silicon dioxide film) is generated on the surface of the silicon wafer.

By repeating the reaction cycle, silicon dioxide is deposited on the inner wall of the reaction tube 1 and the boat 2.
It also adheres to the top. The silicon dioxide powder and dust that have adhered in this way are blown up into the reaction tube 1 when silicon wafers are put in and taken out of the boat, and then they adhere to the surface of the silicon wafer that is intended to produce silicon dioxide, generating foreign matter. It causes. In order to prevent foreign matter from forming on the wafer surface, the reaction tube should be removed and cleaned after the reaction cycle has been repeated a certain number of times or after the total thickness of the produced film reaches a certain amount. It is necessary to replace the reaction tube with a new one.

However, if the reaction tube is replaced frequently, the reaction tube 1, including the inlet side fitting 7 and the outlet side fitting 8, must be removed, which requires a great deal of time and effort, and the equipment is damaged. The operating rate will drop significantly.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and is designed to prevent dust and the like that are stirred up when the silicon wafer is taken in and out of the reaction tube from adhering to the silicon wafer.
It is also an object of the present invention to provide a method for easily exchanging reaction tubes. The structure of the device used in this invention is shown in FIG. In Fig. 2, 1 is an outer reaction tube (hereinafter referred to as outer tube), 2 is a boat,
3 is a silicon wafer, 4 is a gas inlet, 5 is a gas outlet, 6 is a heater, 7 is an inlet side fitting, 8 is an outlet side fitting, 9 is an inner reaction tube (hereinafter abbreviated as the inner tube)
It is. Next, the method of the present invention will be explained with reference to FIG.

First, the silicon wafer 3 is placed on the boat 2 and placed inside the inner tube 9, and in this state, the inner tube 9 is inserted into the outer tube 1. Next, a CVD film is formed as in the conventional method. Then, the inner tube 9 with the silicon wafer 3 still placed therein is taken out from the outer tube 1, and the boat 2 is pulled out from the inner tube 9. Here, the inner tube 9 is the outer tube 1
The dimensions are determined so that the inner surface of the outer tube is covered as completely as possible. Of course, no mounting jig or the like is required for the inner tube, and the cylindrical reaction tube is simply placed inside the outer tube.

Although the above embodiments have been described with reference to the case where the present invention is applied to a silicon dioxide production process, it goes without saying that the present invention is also effective when applied to other processes such as polysilicon and silicon nitride films.

Next, another CVD apparatus that can be used in the present invention will be explained with reference to FIG. In this device, the inner tube 9 is provided with a convex portion 9a and a collar 9b at one end. Providing the convex portion 9a in this manner facilitates attachment and detachment.

Therefore, according to the method of the present invention, a first tube (outer tube), a heater provided outside the first tube, and a second heater provided insertably into the first tube are provided. tube (inner tube), and with the object to be treated placed in the second tube, the second tube and the object to be treated are connected to the first tube.
The second tube is inserted into the second tube, and the object to be treated is placed inside the tube.
The tube inserted into the first tube is inserted into the object to be treated.
A CVD film is generated, and the second tube and the object to be treated are taken out from the first tube while the object to be processed after the CVD film is formed is placed in the second tube. The second tube prevents dust from being drawn in by convection when wafers are taken in and out, and since the wafers are placed inside the second tube when wafers are taken in and out, even if dust is generated, it can be directly removed from the wafers. It can be prevented from adhering to the surface.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a CVD apparatus used in the conventional method, and FIGS. 2 and 3 are cross-sectional views of the apparatus used in the method of the present invention. 1... Reaction tube (first tube), 2... Boat, 3... Silicon wafer, 4... Gas inlet, 5... Gas outlet, 6
...Heater, 7...Inlet side fitting, 8...Outlet side fitting, 9...Inner reaction tube (second tube). Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 Using a first pipe, a heater provided outside the first pipe, and a second pipe insertably provided into the first pipe, the heater is heated inside the second pipe. In a device that generates a CVD film on a processed material, there is a step of inserting the second tube and the processed material into the first pipe while the processed material is placed in the second pipe, and a step in which the processed material is placed in the pipe. a step of generating a CVD film on the object to be treated while inserting a second tube located in the first tube into the first tube;
A method for producing a CVD film, comprising the steps of taking out the second tube and the object to be processed from the first tube while the object to be processed after CVD film generation is placed in the second tube.