JPH03245524A - Cooling method for vapor growth device - Google Patents

Abstract

PURPOSE:To avoid the adherence-deposition of any reaction products by a method wherein the outer wall of a reaction vessel is divided into multiple regions for enabling the outer walls in respective regions to be cooled down by multiple cooling systems; the outer wall temperature and/or the refrigerant temperatures after cooling down process in respective regions are compared to control the refrigerant temperatures for equalizing the outer wall temperatures of the vessel. CONSTITUTION:A cooling system of a reaction vessel 1 is composed of three hoods 101-103 e.g. from upstream side encircling the whole vessel 1; an individual cooling system is composed of cooling blowers 111 113, heat exchamgers 121-123 for air cooling arranged above respective hoods to be exhausted through lower exhaust ports 131-133 while cooling down the outer periphery of the vessel 1 by the cold air from respective blowers 111-113. In such a constitution, the part at the highest temperature of the susceptor for mounting a semiconductor substrate 3 contained in the vessel 1 is cooled down by the cooling system positioned in the central part while the parts at relatively low temperature are cooled down by the other cooling systems on both sides. Furthermore, respective cooling systems are fitted with thermocouples 14 and a blower control system 15 to control the refrigerant temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a cooling method for a vapor phase growth apparatus for forming a thin film on a semiconductor substrate, in which a reaction gas reacts on the inner wall surface of a reaction vessel of the vapor phase growth apparatus. In order to prevent undesirable reaction products from forming and adhering to the inner wall surface, the outer wall of the reaction vessel is divided into multiple areas and multiple cooling systems are installed, and the temperature is controlled individually according to the temperature of each wall surface. The present invention relates to a method for cooling a vapor phase growth apparatus in which the outer wall of a reaction vessel is cooled to a required temperature.

Conventional technology There are various reactor types for vapor phase growth equipment that produces thin films on semiconductor substrates such as silicon, but the semiconductor substrate is placed on a carbon graphite susceptor and housed in the required reaction vessel. The required reaction gas is heated by various heating methods such as radiant heat using an infrared lamp placed outside the reaction vessel, high frequency induction heating using a high frequency oscillation coil, and resistance heating using a resistor embedded in the susceptor. It consists of a configuration in which the vapor phase growth is performed by introducing the

These reaction vessels are generally called quartz chambers and are made of quartz, and in order to prevent reaction products from gas-phase reactions from accumulating on the inner walls of the reaction vessels, the entire vessel is air-cooled or water-cooled and the entire vessel is cooled externally. It is cooled all at once.

For example, in the case of a so-called horizontal vapor phase growth apparatus in which a plate-shaped susceptor is placed horizontally or tilted in a cylindrical reaction vessel placed horizontally, or in the case of a generally polygonal pyramid-shaped susceptor placed in a barrel-shaped reaction vessel placed vertically. In the case of a so-called barrel-type vapor phase growth apparatus in which a susceptor is rotatably arranged, a hood is placed outside an infrared lamp and a high-frequency oscillation coil that are installed around the outer periphery of the container so as to completely surround them.
Cold air from the cooling blower is blown from all directions around the reactor to cool the entire reaction vessel.

In the case of a so-called vertical vapor phase growth apparatus in which a table-shaped susceptor is rotatably arranged inside a dome-shaped reaction vessel and a high-frequency oscillation coil is installed below the susceptor, a large hood similar in shape to the reaction vessel is placed over the susceptor. The entire reaction vessel is cooled while the cold air from the cooling blower is introduced from the upper end of the hood to the lower peripheral edge of the reaction vessel.

Problems to be Solved by the Invention In any conventional vapor phase growth apparatus, radiant heat from the susceptor causes local heating of the reaction vessel, making it impossible to prevent reaction products from accumulating on the walls of the reaction vessel.

When this reaction product is deposited on the wall surface, that area is heated even more locally in the next reaction, resulting in further deposition of the reaction product.

This deposit peels off from the wall surface of the container and adheres to the surface of the semiconductor substrate, causing deterioration in the quality of the semiconductor substrate.

Furthermore, in order to remove this deposit, the reaction vessel must be cleaned periodically, which also causes a decrease in productivity.

In view of the current situation, it is an object of the present invention to provide a means for preventing the deposition of reaction products on the wall surface of a reaction vessel that occurs due to local heating of the reaction vessel.

SUMMARY OF THE INVENTION As a result of various studies aimed at preventing the accumulation of reaction products on the wall surface of a reaction vessel, this invention solves the problem that local heating of the reaction vessel occurs because the entire vessel is cooled all at once. Focusing on the accumulation of reaction products, for example, the outer wall of the reaction vessel is divided into several regions, the temperature of the outer wall of the reaction vessel is constantly monitored, and this is fed back or feedforward to the cooling system. By cooling that region with individual refrigerant temperatures and making the temperature of the outer wall of the reaction vessel uniform, the accumulation of the reaction products can be prevented.
This invention was completed after discovering that the cleaning interval for reaction vessels can be made longer than before.

That is, the present invention provides a method of dividing the outer wall of the reaction container into a plurality of regions and controlling the temperature of each region when cooling the outer wall of the reaction container of the various vapor phase growth apparatuses mentioned above to a required temperature using a refrigerant such as air. A plurality of systems of cooling devices are provided that can individually cool the outer wall, and the temperature of the outer wall and the coolant temperature after cooling are compared between each region to control the coolant temperature of each cooling device. This is a method of cooling a vapor phase growth apparatus characterized by making the temperature uniform.

DISCLOSURE OF THE INVENTION BASED ON DRAWINGS FIG. 1 is a longitudinal sectional view showing a cooling device according to the present invention applied to a horizontal vapor phase growth apparatus. FIGS. 2a and 2b are graphs showing the distribution of container wall temperature, with FIG. 2a showing the conventional case and FIG. 2B showing the case of the present invention.

FIG. 3 is a vertical cross-sectional view showing a cooling device according to the present invention applied to a vertical vapor phase growth apparatus. FIG. 4 is a longitudinal sectional view showing a cooling device according to the present invention applied to a barrel type vapor phase growth apparatus.

Top section, flJ1 Structure As shown in Figure 1, the horizontal vapor phase growth apparatus has a plate-shaped susceptor (SiC-coated carbon graphite) placed in a horizontally arranged cylindrical quartz reaction vessel (1).
2) is placed horizontally, and the semiconductor substrate (3) is placed on the susceptor (2).
) is placed in the reaction vessel (1), heated by an infrared lamp or high-frequency oscillation coil (4) placed around the reaction vessel (1) at a predetermined interval, and then released from the reaction gas inlet (5) of the reaction vessel (1). A growth source gas is introduced, a vapor phase growth reaction is performed on the substrate (3), and the reaction gas is exhausted from the gas exhaust port (6).

The cooling device for the reaction vessel (1) has three hoods (101 to 103) arranged from the upstream side so as to surround the whole, and above each hood (101 to 103) there is a cooling device that sends cooling air. Blower (111-113) and heat exchanger (121-123) for cooling air are provided to constitute an individual cooling system, and each cooling blower (111-113) is provided with a heat exchanger (121-123) for cooling air.
13) is exhausted through the lower exhaust ports (131 to 133) while cooling the outer periphery of the reaction vessel (1).

In order to form an independent cooling system by dividing the outer circumference of the reaction vessel (1) into a plurality of regions, at least the susceptor (2)
It is necessary to divide the reaction vessel (1) into an area where it is heated the most due to the radiant heat from the hood (1), and another area where it is heated the most.
102) and other areas.

In addition, each region, that is, each cooling system, is equipped with a measuring device (143) such as a thermocouple for measuring the temperature of the outer wall of the reaction vessel (1) at a required location or multiple locations within the region, and a measuring device (143) such as a thermocouple to measure the temperature measurement value. In response to this, a control device (15) is installed to control the capacity of the cooling blower (ii3). In addition, in Figure 1, in order to simplify the illustration, the hood (1
03) are shown.

Effect: When heating of the susceptor (2) and the semiconductor substrate (3) begins, the temperature of the outer wall of the reaction vessel (1) is monitored;
In the blower cooling system of an area that is heated more than other areas, the refrigerant temperature is controlled and the reaction vessel (1) of each area is heated.
Control the temperature of the outer wall to be uniform.

In a conventional reaction vessel consisting of a single cooling system, as shown in FIG. 2a, the temperature of the outer wall at the center of the reaction vessel becomes high and the reaction products accumulate on the inner wall surface. In this case, as shown in the figure, since the high-temperature parts can be individually cooled, the temperature of the outer wall of the reaction vessel (1) can be made uniform, and adhesion and deposition of reaction products can be prevented.

According to this invention, it is possible to control the temperature of the reaction vessel so that the reaction gas does not cause reaction deposition on the inner wall of the reaction vessel, and to prevent reaction products from forming on the inner wall of the reaction vessel during vapor phase growth. Deposition can be prevented, the quality of the semiconductor substrates produced is improved, and the cleaning cycle of the reaction equipment is reduced from 1.5 to 1.5 times compared to conventional methods.
Since it can be more than doubled, productivity is also greatly improved.

In this invention, the temperature control method of the reaction vessel is such that, as described above, the temperature of the outer wall of the reaction vessel in each area is monitored and compared, and feedback control is performed on the cooling system in the high temperature area. By monitoring the temperature of the cooling system and the refrigerant temperature of the cooling system, for example, the temperature before and after cooling, and comparing these with those in other areas, it is possible to increase or decrease the amount of air sent to the cooling system in high temperature areas, or to adjust the required heat exchanger capacity in advance. A uniform outer wall surface temperature of the reaction vessel can be obtained by performing feedback or feedforward control such as increasing the temperature.

Example 2 Configuration As shown in FIG. 3, a vertical vapor phase growth apparatus has a table-shaped susceptor (2) on which a semiconductor substrate (3) is placed in a dome-shaped reaction vessel (1), which is rotatably arranged. A high-frequency oscillation coil (4) for heating is provided below the susceptor (2), and a growth source gas is introduced and ejected from a reaction gas nozzle (7) penetrating through the center of the susceptor (2).
) After the vapor phase growth reaction is carried out on the upper surface, the reaction gas is discharged from a gas exhaust port (6) provided below.

The cooling device for the reaction vessel (1) consists of 3 parts, which are divided into 3 parts in the dome-shaped reaction vessel (1) in the horizontal direction so as to surround the whole of the reaction vessel (1).
Two hoods (101 to 1o3) are arranged around the periphery, and each hood (101 to 103) has a cooling blower (111 to 113) that sends cooling air, and a heat exchanger (101 to 113) to cool the air. 121 to 123) are provided to constitute an individual cooling system, and the cold air from each cooling blower (111 to 113) passes through the other exhaust port (131 to 133) while cooling the outer periphery of the reaction vessel (1). It consists of a structure that is exhausted by

Each cooling system is equipped with measuring devices (141 to 14) such as thermocouples to measure the temperature of the outer wall of the reaction vessel (1) in the area
3), and in response to the temperature measurement value, the cooling blower (111
A control device (15) is installed to control the capabilities of the devices (113) to 113).

Effects The cooling method according to the present invention provides a plurality of cooling systems as in the case of Example 1, and controls the temperature of the refrigerant individually according to the temperature of the outer wall surface of the reaction vessel (1) in each region. The outer wall can be cooled to the required temperature.

In the case of a vertical vapor phase growth apparatus, a high-frequency oscillation coil (4) for heating is provided below the susceptor (2), so the reaction vessel (1) in the middle hood (102) area near the susceptor (2) is This is the region that gets heated the most, and the lower region does not require a relatively large amount of cooling because heat is conducted to the base plate (8) side.

Gyofan! As shown in FIG. 4, the barrel-type vapor phase growth apparatus has a substantially polygonal pyramid-shaped susceptor (2) that can accommodate a large number of semiconductor substrates (3) in a vertically arranged barrel-type reaction vessel (1).
) is rotatably arranged, and the reaction vessel (1)
An infrared lamp (9) for heating is provided on the outer periphery of the lamp.

As in Example 2, the cooling device for the reaction vessel (1) has three hoods (10□ to 103) in three areas: upper, middle, and lower.
) are arranged around the cooling blower, forming a three-system cooling system including a cooling blower, a heat exchanger, a measuring device, and a control device.

Effects In the case of barrel type vapor phase growth equipment, a large susceptor (
2) in the middle area of the wide area facing the reaction vessel (1).
) is heated by radiant heat, by intensively cooling this area, the temperature of the outer wall surface of the reaction vessel (1) can be made uniform, and the adhesion and deposition of reaction products can be prevented. According to this invention, in various vapor phase growth apparatuses, it is possible to cool the reaction vessel temperature to a temperature at which reaction products do not accumulate or adhere during vapor phase growth, thereby reducing the adhesion or deposition of reaction products. Therefore, the cleaning of the reaction vessel is different from the conventional method 1.
This eliminates the need for a long period of 5 to 2 times more, improving the productivity of the reactor, and reducing the adhesion of deposited products to the substrate due to low profits, which also suppresses the occurrence of crystal defects in the semiconductor substrate. I can do it.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a cooling device according to the present invention applied to a horizontal vapor phase growth apparatus. FIGS. 2a and 2b are graphs showing the distribution of container wall temperature, with FIG. 2a showing the conventional case and FIG. 2B showing the case of the present invention. FIG. 3 is a vertical cross-sectional view showing a cooling device according to the present invention applied to a vertical vapor phase growth apparatus. FIG. 4 is a longitudinal sectional view showing a cooling device according to the present invention applied to a barrel type vapor phase growth apparatus. DESCRIPTION OF SYMBOLS 1... Reaction container, 2... Susceptor, 3... Semiconductor substrate, 4... High frequency oscillation coil, 5... Reaction gas inlet, 6... Gas exhaust port, 7... Reaction gas nozzle ,
8...Base plate, 9...Infrared lamp, 10
1-103...Hood, 111-113...Blower-121-123...Heat exchanger, 131-133...
・Exhaust port, 141-143...Measuring device, 15...
Control device. Figure 1 Figure 2 (α) (b) Temperature distribution Temperature distribution

Claims (1)

[Claims] 1. When cooling the reaction vessel of a vapor phase growth apparatus, when cooling the outer wall to a required temperature, the outer wall of the reaction vessel is divided into a plurality of regions, and the outer wall of each region can be cooled individually. It is characterized by providing multiple systems of cooling devices, comparing the outer wall temperature and/or coolant temperature after cooling between each region, controlling the coolant temperature of each cooling device, and making the outer wall temperature of the reaction vessel uniform. Cooling method for vapor phase growth equipment.