JPH0468520A - Heat treatment furnace - Google Patents

Abstract

PURPOSE:To lead out a treated wafer from a furnace core tube in a short time by moving the core tube and a heater mutually in accordance with a heat treatment process of the wafer in a heat treatment furnace provided with the core tube for containing the wafer and the heater enclosing the core tube. CONSTITUTION:A front hatch 2 is opened and a boat 6 whereon a wafer 5 is mounted is inserted to a furnace core tube 3. In the process, a heater 4a is positioned at the side of a rear hatch 7. Then, the front hatch 2 is closed, air is evacuated from an evacuation port 8, reaction gas is introduced when a specified vacuum degree is attained, and the heater 4a is moved to a position of the boat 6. Thereby, the wafer 5 is heated to 600 to 850 deg.C and thermally reacts, and a thin film is formed. As soon as film formation of the wafer 5 is finished, the heater 4a moves to the side of the rear hatch 7 from a position of the boat 6. Then, the interior of the furnace core tube is returned to atmospheric state and the boat 6 is taken out of the furnace core tube 3a. It is thereby possible to reduce time for putting in and out of the wafer to and from a furnace without forming an oxide film which is an unnecessary and impeditive film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat treatment furnace for heat-treating a wafer, which is a semiconductor substrate, to perform impurity diffusion, thin film formation, etc.

[Conventional technology]

FIGS. 2 and 3 are a cross-sectional view of a main part and a cross-sectional view taken along line AA, showing an example of a conventional heat treatment furnace. Conventionally, as shown in FIGS. 2 and 3, a heat treatment furnace of this kind has a furnace core tube 3 for housing a boat 6 on which wafers 5 are mounted, a furnace core tube 3, and a furnace core tube 3. It had a heater 4 fixed so as to surround the periphery of the heater 3.

Normally, when forming a thin film on the wafer 5, the temperature inside the furnace core tube is constantly heated to 600 to 850°C by the heater 4. Also, when wafers enter the furnace,
That is, when the boat 6 carrying the wafers 5 is transported into the furnace core tube 3, the wafers 5 are transported to a position in the furnace surrounded by the heaters 4. Furthermore, when entering the furnace, 02 in the clean room is placed between the wafer 5 on the boat 6 and the wafer.
is transported while being rolled up and exposed to the high-temperature atmosphere inside the furnace. Therefore, in a film forming process in which there is a conductive part between the surface of the wafer and the vapor-phase grown film to be formed,
The furnace is completed in a short period of time and the inside of the furnace is evacuated to prevent the intake of

The positional relationship between the boat 6 after the furnace and the heater 4 remains the same until just before the boat 6 is taken out of the furnace.

On the other hand, during unloading, since the boat 6 and wafers 5 are exposed to high temperatures, after the end cap 1 is opened, the boat 6 must be pulled out into the clean room at a speed that does not cause the wafers 5 to break. It was slowly cooled down and pulled out.

[Problem to be solved by the invention]

In the conventional heat treatment furnace described above, the heater is fixed, so the portion of the furnace core tube where the wafer is located is always at 60°C.
It is heated to 0-850°C.

Therefore, while the wafer is being placed in the furnace, the 02 drawn in from outside the furnace core tube is exposed to the high temperature atmosphere inside the furnace, and a thermal oxide film is formed on the surface of the wafer. This thermal oxide film is
If formed in a contact hole, which is a conductive part on a wafer, the contact may cause conduction failure.

Further, when unloading the wafer, there is a drawback that it is necessary to take a long time to cool the wafer sufficiently in order to prevent cracking due to thermal expansion of the wafer.

An object of the present invention is to provide a heat treatment furnace which eliminates such drawbacks and allows processed wafers to be pulled out from the furnace core tube in a shorter time after heat treatment without forming unnecessary oxide films. That's true.

[Means to solve the problem]

The heat treatment furnace of the present invention includes a furnace core tube for storing wafers and a heater surrounding the furnace core tube, in which the furnace core tube and the heater move relative to each other according to the heat treatment process of the wafer. It is characterized by

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of the main parts of a heat treatment furnace showing one embodiment of the present invention. In this heat treatment furnace, as shown in the figure, a heater 4a can be moved to a longer furnace core tube 3a. Of course, in this embodiment, although not shown in the drawings, the furnace core tube 3a is fixed on a stand, and a support stand that supports the heater 4a is attached to the stand via a moving mechanism. . Further, the length of the furnace core tube 3a is designed such that, for example, when the heater 4a moves toward the rear hatch 7, the temperature at a partial position of the boat 6 is less than 300°C. At such a temperature, even if oxygen is present between the wafers 5, the contact openings on the wafers will be
Thermal oxide film hardly grows.

Next, the operation of this heat treatment furnace will be explained. First, open the front hatch 2 and open the board 6 on which the wafer 5 is mounted.
Insert into the furnace core tube 3. At this time, the heater 4a is located on the rear hatch 7 side. Next, the front hatch 2 is closed and air is removed from the exhaust port 8. Next, when a predetermined degree of vacuum is reached, a reaction gas is introduced and the heater 4a is moved to the position of the boat 6. As a result, the wafer 5 has 600 to 8
It is heated to 50° C., causing a thermal reaction and forming a thin film. Next, as soon as the film formation on the wafer 5 is completed, the heater 4a
Move from the position of the boat 6 to the rear hatch 7 side. Next, the inside of the furnace core tube is returned to atmospheric conditions, and the boat 6 is taken out from the furnace core tube 3a. Since the wafer 5 is sufficiently cooled while the heater 4a is moved and the inside of the furnace core tube is returned to the atmosphere, it is possible to take the wafer out of the furnace in a shorter time. Further, although this embodiment has been described using a horizontal heat treatment furnace, a vertical heat treatment furnace can also be applied.

〔Effect of the invention〕

As explained above, the present invention allows the heater to be moved so that the position for heating the furnace core tube can be changed.
Before heating the wafer, oxygen is drawn in from outside the furnace core tube.
It can be degassed and unnecessary heating due to movement of the heater can be avoided. Therefore, there is an effect that a heat treatment furnace can be obtained in which an unnecessary and obstructive oxide film is not formed and the time required for loading and unloading wafers from the furnace can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of a heat treatment furnace showing an embodiment of the present invention, and FIGS. 2 and 3 are a sectional view of the main part and a sectional view taken along line AA, showing an example of a conventional heat treatment furnace. 1... End cap, 2... Front hatch, a
...Furnace core tube, a...Heater 5...Unim 6...Auto, 7...Real hatch, 8...Exhaust port.

Claims (1)

[Claims] A heat treatment furnace comprising a furnace core tube for storing wafers and a heater surrounding the furnace core tube, wherein the furnace core tube and the heater move relative to each other according to the heat treatment process of the wafer. Furnace.