JPH0646624B2 - Heat treatment equipment - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a heat treatment apparatus, and particularly to a heat treatment apparatus (oxidation / diffusion / annealing) using an electric furnace to prevent air from entering a high temperature portion of a furnace core tube. The present invention relates to a heat treatment apparatus suitable for reduction.

[Background of the Invention]

FIG. 1 shows a conventional horizontal electric furnace equipped with, for example, a soft landing mechanism. When heat-treating a wafer using this apparatus, as shown in FIG. 1, a susceptor 2 on which a wafer 1 is placed is set on a fork 4 fixed to a soft landing frame 3, and a horizontal electric furnace (heater 6 , Soaking tube 7) Insert into the furnace core tube 9. After heat treatment for a predetermined time, the wafer 1 is pulled out together with the pedestal 3 and the forks 4. At this time, the fork is made of high-purity quartz and uses a tube having a diameter equal to or larger than that of the heat-treated wafer. When inserting into the fork pipe, a lid cannot be provided at the furnace opening, so that a large amount of air enters the furnace core pipe. Atmosphere gas becomes non-uniform in the tube, especially near the furnace opening, which is a cause of non-uniform film thickness distribution in the wafer surface of 10% or more when a thin oxide film is formed, for example.

[Object of the Invention]

The object of the present invention is to solve the above conventional problems, in the heat treatment process using a heat treatment furnace, prevent the surrounding air from entering the furnace core tube, and perform the heat treatment uniformly,
An object of the present invention is to provide a heat treatment apparatus capable of reducing contamination of a furnace core tube and a heat treatment wafer.

[Outline of Invention]

The present inventor has obtained the following new findings as a result of detailed examination of the invasion of air into the furnace core tube. (1) When air does not have a lid at the furnace opening, it penetrates into the central part of the furnace core without being diluted. (2) By providing a lid at the furnace opening, the concentration of invading air is reduced and the penetration depth is increased. Becomes shallow. Therefore,
It is extremely effective to provide a lid on the furnace opening as a measure for reducing air intrusion into the furnace core tube. On the other hand, as described above, in the electric furnace equipped with the soft landing mechanism, the furnace opening could not be covered. Therefore, as a result of studying measures against air intrusion into the furnace core tube equipped with a soft landing mechanism, it was found that the fork itself should have the function of the furnace mouth cover.

Example of Invention

Embodiment An embodiment of the present invention will be described with reference to FIG. As shown in FIG. 2, in a fork 4 having an outer diameter of 12 cm, the fork having the same diameter as the fork before and after the portion where the susceptor 2 is set has a length of 20 cm.
cm quartz tubes 9 and 10 were provided. Both ends of the cylinder are closed, and holes 11 and 12 having a diameter of 5 mm are opened for removing air. Further, with respect to the cylinder 10, the operation range of the forks is adjusted so that the forks are retained in the furnace core tube and serve as a furnace lid even when the forks are pulled out. The hole 11 provided in the cylinder 9 is provided at the end far from the furnace core tube 8, that is, the end opposite to the wafer 1, so that the outside air that has entered the cylinder 9 when it is inserted into the furnace core tube 8 can flow. However, since the wafer 1 is not contaminated and the hole 12 provided in the tube 10 is provided at the end close to the furnace core tube 8, the gas supplied from the furnace core tube 8 side is supplied into the tube 10. Is filled with, the impurity gas such as the outside air does not flow out from the cylinder 10 even when it is inserted into the furnace core tube 8, and the sample is not contaminated.
The heat treatment can be performed in a desired atmosphere.

When oxidation was performed at 1000 ° C. for 10 minutes using an electric furnace equipped with the above forks and having a soft landing mechanism, the nonuniformity of the oxide film thickness could be controlled to ± 3% or less.

In addition, the effect is not known even if the cylinder part is integrated with the fork.

The above embodiment was carried out with respect to an electric furnace having a soft landing mechanism. However, as shown in FIG. 3, in an electric furnace not having a soft landing mechanism, the effect of the present invention is obtained even when the fork comes into contact with the furnace core tube. It's a cute In addition,
In FIG. 3, symbols 13 and 14 indicate a jig base and a drawing bar, respectively.

As shown in the above embodiments, according to the present invention, by providing the fork supporting the wafer with the function of the lid, even when the electric furnace having the soft landing mechanism is used, the inside of the wafer having the oxidized film thickness is It has the effect of improving the uniformity of distribution.

〔The invention's effect〕

According to the present invention, since it is possible to reduce the invasion of air from the furnace opening into the furnace core tube, (1) with the decrease of the oxygen concentration in the furnace core tube, it is possible to form a thin oxide film with good uniformity, (2) Oxidation of the wafer is reduced by reducing the oxygen concentration during thermal annealing, (3) The amount of dust and contamination around the furnace entering the furnace core tube can be reduced, (4) Due to changes in the environment (humidity, etc.) around the furnace This has the effect of reducing fluctuations in heat treatment characteristics.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining an electric furnace having a conventional soft landing mechanism, and FIGS. 2 and 3 are views showing different embodiments of the present invention. 1 ... Wafer, 2 ... Soceptor, 3 ... Fork stand, 4 ... Fork, 5 ... Fork transport mechanism, 6 ...
Heater, 7 ... Soaking tube, 8 ... Furnace core tube, 9, 10 ... Tube for preventing air intrusion, 11, 12 ... Air vent hole.

Claims (1)

[Claims] 1. A furnace core tube having an opening at one end, a susceptor for inserting a sample to be heat-treated inserted into the furnace core tube through the opening, and a side closer to the furnace core tube than the susceptor. The first cylinder arranged, the second cylinder arranged on the side farther from the furnace core tube than the susceptor, the susceptor, the first cylinder, and the second cylinder in cooperation with each other. In the heat treatment apparatus having a control means to be inserted into the furnace core tube, the first cylinder is provided with an air vent opening only at the end close to the furnace core tube and the other end is closed, and the second cylinder is An opening for bleeding air is provided only at the end far from the furnace core tube and the other end is closed, and the control means is arranged such that when the susceptor is pulled out from the furnace core tube, the first cylinder is inside the furnace core tube. A heat treatment apparatus having a function of controlling so that the heat treatment is stopped.