JPS5823926B2 - heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat treatment apparatus, particularly to a heat treatment apparatus such as an open tube diffusion furnace.

FIG. 1 shows a conventional example of an open tube diffusion furnace used for manufacturing semiconductor devices and the like.

In FIG. 1, 1 is a process tube 2 made of a quartz glass tube or the like, and 3 is a soaking tube made of a magnetic tube or the like placed around the outside of the process tube 1. It is a heater using a high frequency coil etc.
Gas used in the heat treatment is introduced into the process tube 1 from an injector 11 at one end thereof, and is exhausted from a tube port 12 at the other end.

However, in such a diffusion furnace, the larger the cross-sectional area of the pipe opening 12, the more the outside air enters into the interior, as indicated by the reference numeral 4.

When a silicon wafer is oxidized in a steam atmosphere, for example, this circulation of outside air causes an adverse effect such as a large difference in oxide film thickness depending on the position of the silicon wafer in the furnace and the position on the wafer.

The movement of gas within the furnace cross section in section A-A in Figure 1 is as shown by the arrow in Figure 2, and this flow of gas passes through the high-temperature soaking section and is heated. When the gas enters the low-temperature region, it is thought to be cooled near the pipe wall, causing a downward flow along the pipe wall, and as a result of this action, the above-mentioned outside air flows further toward the lower part of the pipe. It makes it easier to get into it.

In order to prevent outside air from entering the pipe from the pipe opening, conventional methods have used end caps that effectively reduce the opening area of the pipe opening, and baffle plates for shielding outside air. A method is adopted as shown in FIG.

That is, in this FIG. 3, 5 is an end cap that closes the pipe opening 12, 6 is a baffle plate inserted into the pipe,
Reference numeral 7 designates a boat for loading and unloading objects to be treated, and 8 designates a pull-out rod of this boat 7.

However, when using the end cap 5, it is not possible to obtain sufficient adhesion to the pipe opening 12 of the process tube 1 with good reproducibility, and when using the baffle plate 6, the inner diameter of the process tube 1 Adjust the diameter of the baffle plate 6 to its full extent,
In particular, it is necessary to reduce the gap between the inner bottom side of the tube and the lower side of the baffle plate, but since large-diameter process tubes are easily deformed by their own weight during heat treatment, this gap cannot be reduced in practice, and outside air It was impossible to prevent this from happening.

In order to prevent the outside air drawing action that occurs in the pipe mouth furnace due to the convection action in the conventional open tube furnace described above, the present invention provides a guide member in the pipe mouth furnace that prevents the convection action. It is something that

The following is an example of applying this invention to an open tube diffusion furnace.
This will be explained in detail with reference to FIGS. 4 to 6.

4 and 5 show one embodiment, and in each of these figures, the same reference numerals as in FIGS. 1 to 3 indicate the same or corresponding parts.

In the open-tube diffusion furnace according to this embodiment, a guide plate 10a such as a quartz glass plate is inserted into the tube opening 12 of the process tube 1 over a predetermined length in a layered manner in the furnace length direction. A guide member 10 is provided.

Therefore, since the guide member 10 is provided in this way, the convection shown in FIG. 2 at the pipe opening 12 is hindered.
This reduces the pressure difference caused by the upward flow, which suppresses the intrusion of outside air.Furthermore, by extending the guide member 10 to just behind the boat 7, the boat 7 can be pulled out. It is possible to reduce the circulation of outside air during the process, and it is possible to obtain functions and effects superior to those of the end cap 5 and the baffle plate 6.

FIG. 6 shows another embodiment of the present invention, and as is clear from FIG. 6, the guide member 10 includes a plurality of guide tubes 10b made of the same material in the furnace length direction. The same effect can be obtained by inserting them in a stacked manner.

As described in detail above, according to the present invention, the circulation of outside air occurring at the pipe mouth can be sufficiently prevented by simply providing a guide member for preventing convection in the pipe mouth furnace. In addition to improving the defects seen in conventional end gear lath baffle plates, a fully automated system can be introduced by using the guide member of this invention in combination with a boat loader. (2) The amount of processing per batch can be increased, and uniform diffusion, oxidation treatment, etc. can be easily performed.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the configuration of a normal open-tube diffusion furnace;
The figure is an explanatory diagram showing the gas flow along line A-A' as above, and Figure 3 is a schematic diagram showing the configuration of an open-tube diffusion furnace to which conventional means for suppressing the circulation of outside air is applied. Fig. 4 is a schematic diagram showing the configuration of an embodiment of the invention when applied to an open-tube diffusion furnace, Fig. 5 is a perspective view of the main parts of the same, and Fig. 6 is a perspective view showing an embodiment of the same. It is a diagram. 1... Process tube, 2... Soaking tube, 3
... Heater, 7 ... Boat, 8 ...
... Pull-out rod, 10 ... Guide member, 10a.
...Guidance board, 10b...Guidance tube.

Claims (1)

[Claims] 1. A heat treatment apparatus in an open-tube furnace, characterized in that a plurality of guide members are provided in the tube opening opening to the outside in a layered manner in the furnace length direction to prevent convection in the front opening of the furnace.