JPH05144736A - Reduced-pressure vapor phase growth apparatus - Google Patents

Abstract

PURPOSE:To prevent a thermal oxide film from being grown on the surface of a semiconductor substrate before a prescribed film is grown when the semiconductor substrate is put into a furnace and to stabilize a semiconductor device in a reduced-pressure vapor phase growth apparatus. CONSTITUTION:In a state that a heating mechanism 7 has been detached from an outer tube 5, semiconductor substrates 1 are loaded on a boat 2, and they are inserted into a vacuum tank which is constituted of the outer tube 5 and a flange 11. After an evacuation operation, an air component is replaced by nitrogen gas. After that, the heating mechanism 7 is moved to a position where the tank is heated around the outer tube 5, and its temperature is stabilized. Then, a material gas is made to flow, and a film as a target is grown. When the film is formed by this procedure, the prescribed film can be grown without growing a thermal oxide film by the residual air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduced pressure vapor phase growth apparatus, and more particularly to a heating mechanism for controlling the temperature of a vacuum chamber of the apparatus.

[0002]

2. Description of the Related Art FIG. 3 shows an outline of conventional vertical vacuum deposition. As shown in FIG. 3, the semiconductor substrate 1 is loaded on the boat 2 on the boat support 3 and inserted into the inner pipe 6.

A vacuum chamber composed of the outer tube 5, the flange 11 and the hatch 4 is exhausted from a vacuum exhaust port 9 by a vacuum exhaust device. A heating mechanism 7 is provided around the outer tube 5 to keep the inside of the tank at a predetermined temperature.

The material gas for vapor phase growth is introduced into the tank through the material gas introduction pipe 8. Vapor growth is heating mechanism 7
After inserting the semiconductor substrate 1 into a tank previously maintained at a constant temperature (500 to 800 ° C.) by, the vacuum is continuously evacuated to −10 ⁻² Torr, and an inert gas is flown from the material gas introduction pipe 8. This is realized by stabilizing the temperature of the semiconductor substrate while maintaining the pressure of -10 ^-1 Torr and then flowing the material gas.

At this time, since the semiconductor substrate is inserted into the tank under atmospheric pressure, the semiconductor substrate is exposed to atmospheric components at a high temperature (500 to 800 ° C.) from the start of insertion to the completion of vacuum evacuation. Therefore, an oxide film grows on the surface before growing a desired film.

As a preventive measure, a method is often used in which a semiconductor substrate is inserted while a large amount of nitrogen gas is allowed to flow from the nitrogen gas inlet 16 from the real side of the tank to reduce atmospheric components in the tank.

[0007]

In this conventional vapor phase growth apparatus, it is possible to reduce atmospheric components in the tank by inserting a semiconductor substrate while flowing a large amount of nitrogen gas from the inner side of the tank. Since the tank entrance side is open,
It is not possible to completely remove atmospheric components. For this reason,
There is a high risk that an extremely thin oxide film will grow on the surface.

With the recent miniaturization of semiconductor devices,
The thinning of the capacitance insulating film and the miniaturization of contacts have advanced, and the ultra-thin oxide film before film formation, which has not been a problem in the past, also has a great influence on the device yield. However, the conventional device has a problem that a stable yield cannot be obtained.

Further, the flow of the nitrogen gas in the conventional vapor phase growth apparatus is opposite to the flow direction of the material gas, and there is a problem that the particles are likely to be wound up and the yield of the semiconductor device is lowered. It was

An object of the present invention is to provide a semiconductor substrate insertion furnace,
It is an object of the present invention to provide a low pressure vapor phase growth apparatus that prevents a thermal oxide film from growing on the surface of a substrate before the growth of a predetermined film.

[0011]

In order to achieve the above object, in a reduced pressure vapor phase growth apparatus according to the present invention, a reduced pressure for growing a desired thin film on a semiconductor substrate has a vacuum chamber and a heating mechanism. In the vapor phase growth apparatus, a vacuum chamber is used to grow a thin film on a semiconductor substrate inside, and a heating mechanism is for heating the vacuum chamber and is provided so that it can be displaced relative to the vacuum chamber. It is a thing.

[0012]

The semiconductor substrate is inserted by keeping the inside of the bath at a low temperature to prevent the particles from being wound up and to prevent the oxide film from growing on the surface of the substrate.

[0013]

The present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a reduced pressure vapor phase growth apparatus according to an embodiment of the present invention.

In FIG. 1, the structure of the vacuum chamber, the gas introduction pipe, and the vacuum exhaust method are the same as those of the conventional device.

In the figure, according to the invention, the heating mechanism 7
Is attached to the heating mechanism support guide 12 of the heating mechanism moving mechanism 10, and the heating chamber moving mechanism 10 causes the vacuum chamber (4,
It is provided so as to be relatively displaceable with respect to (5, 11).

Therefore, the heating mechanism 7 can select a position where the vacuum chamber is heated around the outer tube 5 and a position where the vacuum chamber is completely removed from the outer tube 5 and the vacuum chamber is not heated.

Further, the vacuum chamber has a structure in which nitrogen gas, material gas and pretreatment gas can be supplied by the respective supply systems 13, 14 and 15.

The film formation in this apparatus is performed in the following procedure. First, with the heating mechanism 7 removed from the outer tube 5, the semiconductor substrate 1
Is loaded on the boat 2 and is inserted into the vacuum chamber for vacuum evacuation.

After the vacuum chamber is evacuated to a pressure of -10 ^-3 Torr or less, 5 SLM of nitrogen gas is supplied from the nitrogen gas supply system 13 through the material gas introduction pipe 8. In this state, the heating mechanism 7 is moved to a position where the tank is heated around the outer tube 5,
Wait 40 minutes for the temperature to stabilize.

After that, the nitrogen gas is switched to the material gas of the material gas supply system 14 to form a film. At this time, the heating mechanism 7
Is divided into 3 zones and temperature can be controlled independently,
The temperature is set in advance so that the film thickness in the vacuum chamber is uniform, and is maintained at a constant temperature distribution regardless of the movement of the heating mechanism 7.

Example 2 Next, film formation in Example 2 of the present invention will be described. With the heating mechanism 7 removed from the outer tube 5, the semiconductor substrate is inserted into the vacuum chamber and evacuated.

After evacuation was performed until the pressure in the vacuum chamber became 10 ⁻³ Torr or less, 10% HF gas was supplied to 10% from the pretreatment gas supply system 15 while flowing 1 SLM of nitrogen gas.
Run at 0 sccm for 10 minutes.

After stopping the HF gas, 5 SL of nitrogen gas is supplied.
After flowing for 10 minutes, the heating mechanism 7 is moved to a position for heating the tank around the outer tube 5, and the temperature is stabilized for 40 minutes. After that, the nitrogen gas is switched to the material gas to form a film.

In Example 1, the thickness of the oxide film before the growth of the predetermined film is 4 to 5Å, which is the same as the film thickness that has already been grown before the start of the work, compared with 10 to 20Å of the conventional example. Has been reduced.

On the other hand, in the second embodiment, since there is pretreatment with HF gas, there is almost no oxide film, and 0 to 1
It has become Å.

[0026]

As described above, the present invention has a structure in which the relative position of the heating mechanism of the reduced-pressure vapor phase growth apparatus to the vacuum chamber is changed. After the pre-treatment, the heating mechanism is moved to heat the inside of the bath, so compared to the conventional technology, the growth of ultra-thin oxide film on the surface of the semiconductor substrate is completely prevented without the risk of particle winding. Vapor growth can be realized, and the yield of semiconductor devices can be stabilized.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a reduced pressure vapor phase growth apparatus according to the present invention.

FIG. 2 is a schematic view showing a conventional low pressure vapor phase growth apparatus.

[Explanation of symbols]

 1 semiconductor substrate 2 boat 3 boat support 4 hatch 5 outer pipe 6 inner pipe 7 heating mechanism 8 material gas introduction pipe 9 vacuum exhaust port 10 heating mechanism moving mechanism 11 flange 12 heating mechanism support guide 13 nitrogen gas supply system 14 material gas supply System 15 Pretreatment gas supply system 16 Nitrogen gas inlet for oxide film prevention

Claims (1)

[Claims] 1. A reduced pressure vapor phase growth apparatus for growing a desired thin film on a semiconductor substrate, comprising a vacuum chamber and a heating mechanism, wherein the vacuum chamber internally grows a thin film on the semiconductor substrate. The reduced pressure vapor phase growth apparatus is characterized in that the heating mechanism heats the vacuum chamber and is provided so as to be capable of relative displacement with respect to the vacuum chamber.