JPH044749B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a heat treatment apparatus, and particularly to a vertical diffusion furnace for heat treating semiconductor substrates (wafers).

(Prior art) Conventionally, as a vertical diffusion furnace, for example, Fig. 4 a and b
The following are known.

In the figure, 1 is a reaction tube having an opening 2 at the bottom. At the top of this reaction tube 1 is an inlet 3 for the reaction gas.
An exhaust port 4 is provided in the lower side wall of the reaction tube 1.
is provided. The opening 2 of the reaction tube 1 is provided with a cap 5 that moves up and down, thereby opening and closing the opening 2. A boat pedestal 6 is provided above the cap 5, and a boat 7 for setting a plurality of wafers (not shown) horizontally is provided on the boat pedestal 6. The boat pedestal 6 is provided to efficiently hold the boat 7 in the soaking area or to block heat radiation from inside the reaction tube 1 to prevent the temperature of the cap 5 from rising. An exhaust section 9 is provided on the lower side wall of the jacket 8 to prevent the reaction gas from staying in the jacket.

In a vertical diffusion furnace having such a structure, the reaction gas enters through the inlet 3 of the reaction tube 1, flows around the boat 7, and is then discharged to the outside through the opening 9 of the jacket 8 and the exhaust port 4 of the reaction tube 1. be done. Also,
When the cap 5 is lowered after the heat treatment, it becomes as shown in FIG. 4b. Here, the opening 2 of the reaction tube 1 and the opening 9 of the jacket 8 are each exposed to the outside air, but the boat 7 is shielded from the outside air by the jacket 8. If the gap between the reaction tube 1 and the jacket 8 is very small and the cross-sectional area of the opening is small, the reaction gas will be exhausted from the exhaust port 3 of the reaction tube 1 and the opening 9 of the reaction tube 1 and the jacket 8, and the reaction gas will be exhausted from the outside air. never enters jacket 8.

However, in actual cases, since the jacket 8 is moved up and down, there is a certain amount of clearance as an operational margin, and the reaction gas is transferred between the reaction tube 1 and the jacket 8.
The gas is sufficiently exhausted through the gap between the tubes and the exhaust port 4 of the reaction tube 1.
Therefore, it flows back through the opening 9 of the jacket 8, which is lower than the opening 2 of the reaction tube 1. This causes contamination and the like to the wafers set on the boat 7, causing deterioration of the characteristics of the semiconductor device.
By the way, if the flow rate of the reaction gas is increased extremely, the exhaust gas will no longer be exhausted only from the gap between the reaction tube 1 and the jacket 8 or from the exhaust port 3 of the reaction tube 1, and the reaction gas will also be exhausted from the opening 9 of the jacket 8 and will be exhausted to the outside air. backflow is prevented. However, in order to prevent backflow, a large flow rate of the reaction gas is required, and there are problems such as the need to increase the size of the flow rate control device of the gas doping unit. Further, there are problems such as a large amount of high-temperature reaction gas being released into the clean room.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and provides a heat treatment apparatus that prevents outside air from flowing back into the reaction tube and can obtain wafers with good device characteristics. The purpose is to

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a reaction tube having an opening for entering and exiting a boat at one end side and having an inlet and an outlet for a reaction gas, and an opening of the reaction tube. A cap that opens and closes, a boat installed directly on the cap or via a boat cradle, a cylindrical jacket provided on the outer periphery of the boat and having an exhaust opening, and an opening for the reaction tube after heat treatment. and a ring-shaped member that can be divided into a plurality of parts to close the gap between the jacket and the jacket.

(Function) According to the present invention, the gap between the reaction tube and the jacket can be effectively reduced by providing a ring-shaped member that can be divided into a plurality of parts to close the gap between the opening of the reaction tube and the jacket after heat treatment. , it is possible to prevent outside air from flowing back into the reaction tube. Therefore, if a semiconductor device is manufactured from a wafer heat-treated using the heat treatment apparatus according to the present invention, a semiconductor device having good device characteristics can be obtained.

(Example) An example of the present invention will be described below in Figures 1a and b and 2.
This will be explained with reference to the figures and FIG.

11 in the figure is a reaction tube having an opening 12 at the bottom. A reaction gas inlet 13 is provided at the upper part of the reaction tube 11, and an exhaust port 14 is provided at the lower side wall of the reaction tube 11. The reaction tube 1
A cap 15 that moves up and down is provided in the first opening 12, and the opening 12 is opened and closed by this. A boat pedestal 16 is provided above the cap 15 and has a protrusion 16a at the center of the top. Here, the boat pedestal 16 is used to efficiently hold the boat described later in the soaking area or to hold the reaction tube 1
The cap 15 is provided in order to block heat radiation from inside the cap 15 and prevent the temperature of the cap 15 from rising. A plurality of wafers (not shown) are mounted on the protrusion 16a of the boat pedestal 16.
A boat 17 is provided for horizontally setting. A cylindrical jacket 18 surrounding the boat 17 is provided on the edge of the boat pedestal 16. An exhaust section 19 is provided on the lower side wall of the jacket 18 to prevent the reaction gas from remaining in the jacket. In addition, the reaction tube 1
A ring-shaped member 20, which is divided into two parts, is provided near the lower end of the ring 1, as shown in FIG. When the cap 15 is lowered after heat treatment, this member 20 is assembled to fill the gap between the reaction tube 11 and the jacket 18, as shown in FIG.
At the bottom of the ring-shaped member 20, the member 20
A sensor 21 is provided that detects the position of and automatically adjusts the position to an appropriate position.

In a vertical diffusion furnace with such a structure, the reaction tube 1
The reaction gas introduced from the inlet 13 of the reaction tube 1 passes around the boat 17 and is further discharged to the outside through the exhaust part 19 of the jacket 18 and the outlet 14 of the reaction tube 11. At this time, the ring-shaped member 20 is not needed and is located away from the lower end of the opening 12 of the reaction tube 11 (as shown in FIGS. 1A and 2). on the other hand,
When the cap 18 is lowered after the heat treatment, the ring-shaped member 20 moves to the lower end of the opening 12 of the reaction tube 11 and comes as close as possible to the outer wall of the jacket 18 to form a ring. Here, the member 20 fills the gap between the reaction tube 11 and the jacket 18 and reduces the area of the opening 12 of the reaction tube 11.

According to the above embodiment, since the ring-shaped member 20 that can be divided into a plurality of parts is provided near the reaction tube 11, the following effects are achieved.

When the cap 15 is lowered after heat treatment, if the member 20 is combined and moved to the lower end of the reaction tube 11, the gap between the reaction tube 11 and the jacket 18 is filled by the member 20, and the gap is effectively filled. becomes smaller. As a result, this gap and the exhaust port 14 of the reaction tube are insufficient to exhaust the reaction gas, and the gas that cannot be exhausted from between the walls and the exhaust port of the reaction tube is pushed downward. Therefore, the reaction gas is also exhausted from the exhaust part 19 of the jacket 18, and backflow of outside air is prevented.

It is no longer necessary to make the gap between the jacket 18 and the reaction tube 11 smaller than necessary, the margin of vertical movement is increased, and troubles are reduced.

By combining it with the ring-shaped member 20, a large degree of freedom is created in the shape of the jacket 18, and various deformed jackets can now be used.

It is possible to reduce the release of hot reaction gas into the clean room.

The temperature near the opening 12 of the reaction tube 11 can be reduced.

In the above embodiment, a case where the ring-shaped member is divided into two parts is described, but the present invention is not limited to this, and the ring-shaped member can be divided into three or more parts.

Further, in the above embodiment, a case has been described in which the position of the ring-shaped member is detected by a sensor, but the sensor is not necessarily necessary, and the position may be adjusted manually, for example.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a heat treatment apparatus that prevents outside air from flowing back into the reaction tube and that produces a semiconductor device with good element characteristics.

[Brief explanation of drawings]

Figure 1a is a sectional view of a vertical diffusion furnace according to an embodiment of the present invention during heat treatment, Figure 1b is a sectional view of the same vertical diffusion furnace after heat treatment, and Figure 2 is a reduced version of Figure 1a. 3 is a reduced plan view of FIG. 1b, FIG. 4a is a sectional view of a conventional vertical diffusion furnace during heat treatment, and FIG. 4b is a sectional view of the same vertical diffusion furnace after heat treatment. be. 11... Reaction tube, 12... Opening, 13... Inlet,
14... Discharge port, 15... Cap, 16... Boat pedestal, 17... Boat, 18... Jacket, 19... Discharge part, 20... Ring-shaped member, 21... Sensor.

Claims (1)

[Scope of Claims] 1. A reaction tube having an opening for entering and exiting a boat at one end and having an inlet and an outlet for reactant gas, respectively, and a cap for opening and closing the opening of the reaction tube;
A boat attached directly to the cap or via a boat cradle, a cylindrical jacket provided on the outer periphery of the boat and having an exhaust opening, and a gap between the opening of the reaction tube and the jacket after heat treatment. A heat treatment apparatus comprising a ring-shaped member that can be divided into a plurality of parts. 2. The heat treatment apparatus according to claim 1, wherein the ring-shaped member is divided into two parts. 3. A claim characterized in that the boat is attached to the cap via a boat holder, and a sensor is provided below the ring-shaped member to adjust the member to an optimal position between the reaction tube and the jacket. The heat treatment apparatus according to item 1.