JPH05148100A - Apparatus for heat treatment of semiconductor and method therefor - Google Patents

Abstract

PURPOSE:To increase the cooling rate after heat treatment and to unify the semiconductor properties by making a leak hole passing through the grinding surfaces between a cylindrical tank accommodating a semiconductor together with a treatment raw material gas and its lid so as to be openable and closable. CONSTITUTION:A lid 5 is placed over a cylindrical tank 1 for accommodating a semiconductor wafer 13 and a treatment raw material gas 14 to tightly seal both the units through the grinding surfaces 3 and 6 of both the units. The lid 5 and the cylindrical tank 1 are elevatably supported by an upper shaft 8. A leak hole 7 is made so as to pass through the grinding surfaces 3 and 6 and the leak hole 7 is designed so as to be openable and closable by rotating the upper shaft 8. The cylindrical tank 1 is accommodated in a chamber 9 and the chamber 9 is filled with an inert gas 10 having a pressure higher than the vapor pressure in the cylindrical tank 1 in a state where the leak hole 7 is closed. The semiconductor wafer 13 is heat-treated by heaters 15 and 16 and the leak hole 7 is then opened so as to cool the semiconductor wafer 13 while leaking the inert gas 10 in the chamber 9 into the cylindrical tank 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor heat treatment apparatus.

[0002]

2. Description of the Related Art A compound semiconductor wafer containing a high dissociation pressure element such as GaAs or InP is exposed to high temperatures when exposed to As,
There is a problem that P and the like cause dissociation and the surface of the wafer is roughened to impair the crystallinity. 3 and 4 show a conventional apparatus for heat treating a semiconductor while suppressing these dissociations.
The heat treatment apparatus shown in FIG.
A high dissociation pressure element simple substance 14 such as s or P is accommodated, and the semiconductor wafer 13 is fixed to the support 12 and accommodated therein. The cylindrical container 1 is supported by the lower shaft 4 and is arranged in a heating furnace including heaters 15 and 16. Then, after evacuating the inside of the cylindrical container 1, an inert gas is supplied, the lid 5 supported by the upper shaft 21 is lowered, and the sliding surfaces 3 and 6 are joined and hermetically sealed. The sliding surfaces 3 and 6 may have an inverted truncated cone shape. Thereafter, the heater 16 heats the high dissociation pressure element simple substance 14 to maintain a predetermined vapor pressure, and the heater 15 heats the semiconductor wafer 13 to perform heat treatment. After heat treatment, heater 1
The output of 5 and 16 is reduced or stopped and cooled. Figure 4
In the heat treatment apparatus of FIG. 3, the heater 17 is arranged below the heater 16 to provide a low temperature zone for cooling in the apparatus of FIG. It moves to and cools.

[0003]

The above heat treatment apparatus is
The high dissociation pressure element gas may leak from the joint between the container and the lid to contaminate the environment, and the high dissociation pressure element may be desorbed from the semiconductor wafer surface due to the leakage. Further, it is necessary to make the semiconductor crystal uniform in various characteristics, and the characteristics may vary depending on the annealing conditions from the heat treatment step. Therefore, it may be necessary to cool the heat treatment temperature early. However, in the apparatus of FIG. 3, it is difficult to obtain a sufficiently high cooling rate due to the radiant heat remaining in the container. Further, in the apparatus shown in FIG. 4, the operation is complicated because a plurality of temperature zones are passed, and it is difficult to maintain the same annealing condition. Therefore, the present invention eliminates the above drawbacks,
An object of the present invention is to provide a heat treatment apparatus and a heat treatment method capable of preventing leakage of a high dissociation pressure element gas and obtaining a high cooling rate in a cooling step.

[0004]

The present invention has a cylindrical container for accommodating a semiconductor and a processing gas raw material and a lid, and it is possible to seal the lid and / or the cylindrical container up and down by the sliding surface of both. A heat treatment for a semiconductor in which a shaft for supporting the semiconductor is provided, a heater for heating a semiconductor and a processing gas raw material is provided around the cylindrical container, which are housed in a chamber, and a reduced pressure exhaust system and an inert gas supply system are connected to the chamber. In the apparatus, a heat treatment apparatus for a semiconductor, characterized in that a leak hole penetrating the abutting surface is provided, and the leak hole can be opened and closed by rotating the shaft, and the semiconductor heat treatment apparatus is used. Then, with the leak hole closed, the chamber is filled with an inert gas having a pressure higher than the vapor pressure inside the cylindrical container to heat-treat the semiconductor, and then the leak hole is closed. A semiconductor heat treatment method characterized by cooling the semiconductor while leaking inert gas in the chamber in the cylindrical container and release. In addition, in order to more completely prevent the high dissociation pressure element gas leak from the cylindrical container, it is preferable that the sliding portion of the cylindrical container and the lid has an inverted truncated cone shape. In addition, it is preferable to provide a flexible portion on the support shaft of the lid or the cylindrical container to enable correction of a slight misalignment between the cylindrical container and the lid and inclination of the cylindrical container.

[0005]

1 is a cross-sectional view of a semiconductor wafer heat treatment apparatus according to one embodiment of the present invention, and FIG. 2 is a diagram showing the opening and closing of a leak hole provided on the sliding surface between the upper portion of the cylindrical container and the lid shown in FIG. It is an enlarged view for explaining. A thin tube 2 at the lower end of the cylindrical container 1.
Are connected to each other, the sliding surface 3 at the upper end is formed into an inverted truncated cone shape, the high dissociation pressure element simple substance 14 is accommodated in the thin tube 2, and the semiconductor wafer 13 is fixedly accommodated in the support 12 in the cylindrical container 1. .. It is also possible to replace the wafer support 12 and heat-treat the semiconductor ingot. The bottom surface of the lid 5 is also provided with a truncated cone-shaped sliding surface 6 with respect to the sliding surface 3 of the cylindrical container 1. The cylindrical container 1 is supported by the lower shaft 4 and the lid 5 is supported by the upper shaft 8, and is disposed in a chamber 9 equipped with heaters 15 and 16. Then, the vacuum exhaust pipe 11 and the inert gas supply pipe 10 are connected to the bottom of the chamber 9. The leak hole 7, which is a feature of the present invention, is
It is provided so as to penetrate the sliding surface 3 of the cylindrical container 1 and the sliding surface 6 of the lid 5, and the leak hole 7 is opened and closed by rotating the upper shaft 8 as shown in FIG. In addition, although the heat treatment apparatus of FIG. 1 explained the case where a vertical cylindrical container was used, it can be arranged horizontally.

Next, a heat treatment procedure for the semiconductor wafer will be described. First, the high dissociation pressure element simple substance 14 and the semiconductor wafer 13 are housed in the cylindrical container 1, and the cylindrical container 1 is placed in the chamber 9 by the lower shaft 4 and sealed by the sliding surface. Then, the inside of the chamber 9 is evacuated and then the upper shaft 8 is lowered to bring the lid 4 into contact with the cylindrical container 1 to seal it. Then, with the leak hole 7 closed, an inert gas is introduced into the chamber 9 and kept at a pressure higher than the pressure in the cylindrical container at the time of heat treatment, and then the heaters 15 and 16 are energized to provide a high dissociation pressure element. The simple substance 14 and the semiconductor wafer 13 are heated, the predetermined high dissociation pressure element gas vapor pressure is held in the chamber 9, and the semiconductor wafer 10 is held at the processing temperature for heat treatment for a predetermined time. After the heat treatment is completed, the upper shaft 8 is rotated to slightly open the leak hole 7, the heaters 15 and 16 are stopped to cool it to near room temperature, and then the chamber 9 is evacuated once and then the cylindrical container 1 is removed. The lid 5 is released, and then the inside of the chamber 9 is returned to atmospheric pressure with an inert gas, and then the chamber 9 is opened to take out the semiconductor wafer.

According to the present invention, the leak hole is provided on the sliding surface of the cylindrical container and the lid as described above, the leak hole can be opened and closed by rotating the lid, and the leak hole is opened in the cooling step after the heat treatment. The cooling rate can be increased, and the cooling rate can be easily controlled.

[0008]

EXAMPLE A GaAs 4-inch wafer was heat-treated in the heat treatment apparatus shown in FIG. First, metal As is put into the thin tube of the container, the above-mentioned wafer polished to a mirror state is set on a flat support tool made of carbon, and they are housed in a quartz container in which a Nikawa ring is bonded to the bonding portion. Then, the container was placed in the chamber, and the entire chamber was evacuated to about 2.7 × 10 ⁻⁴ Pa with the lid opened. Then, the lower shaft was driven to bring the container into contact with the lid, and a load was applied to the upper shaft to bring them into close contact.
At that time, the leak hole was kept closed. Then, nitrogen gas is applied to the chamber for several atm or more, and the wafer portion is heated to 1200 ° C. just below the melting point of GaAs at a temperature of metal A
s was heated to 610 ° C. and annealed as it was for 8 hours.

Thereafter, the following cooling operations (1) to (5) were performed, and the average cooling rate was about 7 to 10 ° C./minute for 25 to 35 minutes. Loosen the load applied to the lid, rotate the upper shaft, slightly open the leak hole and allow the nitrogen gas in the chamber to flow into the container, then evacuate the chamber again and close the leak hole. The lid was closed by applying a load, nitrogen gas was allowed to flow into the chamber, and the above operations 1 to 3 were repeated until the wafer was cooled to a predetermined temperature.
Then, the wafer was taken out after cooling to room temperature as usual. For comparison, according to the conventional method, the annealed wafer was cooled in a normal method with the leak holes closed, the heater was stopped in a normal method at an average cooling rate of about 5 ° C./minute to 950 ° C. in 50 minutes, After that, the wafer was taken out after cooling to room temperature by a usual method. As described above, in the embodiment of the present invention, the wafer can be cooled at a higher cooling rate as compared with the conventional method, and the obtained GaAs wafer has more As precipitates, which is one of its characteristics. It was possible to reduce the size and make it uniform.

[0010]

According to the present invention, by providing a leak hole in the sliding portion between the cylindrical container and the lid, the cooling rate after the heat treatment is increased, the cooling rate is easily controlled, and the characteristics of the semiconductor crystal are facilitated. Can be made uniform.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heat treatment apparatus that is one specific example of the present invention.

FIG. 2 is an enlarged view for explaining opening and closing of a leak hole provided in a sliding portion between the cylindrical container and the lid of FIG.

FIG. 3 is a sectional view of a conventional heat treatment apparatus.

FIG. 4 is a sectional view of another conventional heat treatment apparatus.

Claims (2)

[Claims] 1. A cylindrical container for containing a semiconductor and a processing gas raw material, and a lid, which can be hermetically sealed by a sliding surface between them.
A shaft for supporting the lid and or the cylindrical container so as to be able to move up and down is provided, a heater for heating the semiconductor and the processing gas raw material is provided around the cylindrical container, and they are housed in a chamber,
In a semiconductor heat treatment apparatus in which a reduced pressure exhaust system and an inert gas supply system are connected to the chamber, a leak hole penetrating the abutting surface is provided, and the shaft can be rotated to open and close the leak hole. A semiconductor heat treatment apparatus characterized by: 2. The semiconductor heat treatment apparatus according to claim 1, wherein the chamber is filled with an inert gas having a pressure higher than the vapor pressure inside the cylindrical container with the leak hole closed to heat the semiconductor. Then, the semiconductor heat treatment method is characterized in that the semiconductor is cooled while the leak hole is opened to leak the inert gas in the chamber into the cylindrical container.