JPS6342375A - Vapor growth device - Google Patents

Abstract

PURPOSE:To optimize the concn. of the gaseous flow in the reaction chamber of a barrel type vapor growth device by constituting the reaction chamber of a bell-jar having the shape, the outside circumferential length of which decreases gradually from the upper gas introducing port side toward the lower gas discharge port side. CONSTITUTION:A susceptor 10 for holding the material 1 is constituted of the approximately pyramidal shape consisting of plural slopes and is mounted to a revolving shaft 11 suspended perpendicularly from a base plate in such a manner that said susceptor can be freely rotated. The susceptor 10 is introduced into the tulip-shaped bell-jar 12. A gaseous raw material is introduced from the gas introducing port 14 provided with an upper closing member 13 into the reaction chamber 15 and is discharged from the gas discharge port 16 provided to a lower closing member 16. A high-frequency coil 17 is disposed to the outside circumferential part of the bell-jar 12. The bell-jar 12 in the above-mentioned constitution is formed to the shape, the outside circumference of which is gradually decreased from the gas introducing port 14 side toward the gas discharge port 16 side. The gaseous flow and concn. in the reaction chamber 15 are thereby optimized and the uniformity of the thickness of the formed thin film is improved, by which the yield of the product is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to an improvement in a barrel-type vapor phase growth apparatus for vapor phase growth of a required semiconductor thin film on a substrate by chemical reaction, ensuring an optimal raw material gas flow. The present invention relates to a vapor phase growth apparatus that can improve film thickness uniformity and product yield.

BACKGROUND ART Today, in the mass production of integrated circuits, raw material gas is introduced from one side into a bell jar containing a substrate heated to high temperature, and a thin film of a specific composition is formed on the substrate by a vapor phase chemical reaction.
A vapor phase growth apparatus is used in which exhaust gas is discharged from the other end of a bell jar.

In general, in order to uniformly form a thin film to the required thickness on a substrate using a vapor phase growth apparatus, it is necessary to optimally select and maintain various factors such as temperature, pressure, gas concentration, and substrate surface. .

Various types of vapor phase growth equipment, such as horizontal, vertical, and barrel types, have been developed based on the fluid dynamics of the raw material gas in the bell jar and the heating method of the substrate. It is known that the uniformity of thickness is adversely affected, and in particular, it has been pointed out that non-uniform gas concentration within the reaction chamber causes a decrease in yield.

The barrel type vapor phase growth apparatus shown in FIG. 3 has the advantages of horizontal and vertical types, and the susceptor (2) that holds the substrate (1) and is rotationally driven has a plurality of (IA'f = JF planes). The raw material gas is supplied to a cylindrical reaction chamber (5) through a gas inlet (4) provided in a member that closes the upper opening of a dome-shaped or tulip-shaped bell jar (3) as shown in the figure. The gas is introduced into the bell jar (3
), an infrared lamp or a high frequency coil (high frequency coil (7) is shown here) is arranged. In addition, in the case of the barrel type using the dome-shaped bell jar, all of the bell jars are arranged upside down except that the susceptors (2) are tilted in the same direction.

In such a vapor phase growth apparatus, there is a tendency to increase the number of substrates processed in one batch, but uneven gas flow and uneven gas concentration distribution pose problems, so it is difficult to uniformly process substrates and susceptors that are heated objects. For the purpose of heating, it is necessary to adjust the distance between the high frequency coil (7) of the heating source and the susceptor (2), consider the arrangement of the high frequency coil (7), and in the case of infrared lamps, adjust the output for each band. Then, the amount of heat to the heated body is controlled, the temperature distribution on the substrate (1) is made uniform, and the gas flow rate is increased by means such as reducing the pressure to increase the supply of raw material gas, A method was taken to improve the non-uniformity of the film thickness on each substrate in the gas flow direction.

However, even with the above method, the non-uniformity of the gas concentration distribution is not resolved and the thickness of the grown thin film becomes non-uniform. Therefore, the susceptor is placed approximately parallel to the gas flow, and the gas concentration in the vertical direction on the substrate is measured. A method of supplying replenishment raw material gas based on the results has been proposed (Japanese Patent Application Laid-open No. 75999/1983), but performing such gas concentration measurement and replenishment in real time requires sophisticated calculation control and requires operational labor. This led to various problems.

Purpose of the Invention The present invention is capable of improving the uniformity of the thickness of a thin film grown on a substrate in a barrel-type vapor phase growth apparatus with simple operation without complicated gas concentration control. The aim is to create a vapor phase growth device that can improve product yield.

Structure and Effects of the Invention As a result of various studies aimed at uniformly growing a thin film on a substrate in a vapor phase growth apparatus, the present invention has developed a structure in which the outer circumference gradually decreases from the gas inlet side toward the lower gas outlet. It has been discovered that by configuring the reaction chamber with a bell jar made of 300% gas, the gas flow and concentration within the reaction chamber can be optimized, the uniformity of the formed thin film thickness can be improved, and the product yield can be improved.

That is, this invention arranges a pyramid-shaped susceptor with its top facing the gas inlet in a bell jar with gas inlet and outlet ports in the vertical direction, and performs chemical reactions such as hydrogen reduction and thermal decomposition. In a barrel-type vapor phase growth apparatus that grows a crystal layer on a substrate in a vapor phase, from the gas inlet side toward the lower gas outlet,
This is a vapor phase growth apparatus characterized in that a reaction chamber is constituted by a bell jar having a shape whose outer circumference gradually decreases.

In this invention, the gas discharge 1 below the gas inlet side
7J, by configuring the reaction chamber with a bell jar with a shape whose outer circumference gradually decreases, the gas flow and concentration within the reaction chamber can be optimized, improving the uniformity of the formed thin film thickness and improving the product process. However, the relationship between the inclination angle of the susceptor and the aperture inclination angle of the pyramidal bell jar with the top facing the gas inlet side depends on the dimensions of the bell jar, the two dimensions of the susceptor shape, the gas flow, etc. It is necessary to make an appropriate selection taking into account the following conditions.

DISCLOSURE OF THE INVENTION BASED ON THE DRAWINGS FIG. 1 is a longitudinal sectional view of a barrel-type vapor phase growth apparatus according to the present invention. FIG. 2 is a longitudinal sectional view of another vapor phase growth apparatus of the present invention.

In the vapor phase growth apparatus shown in FIG. 1, a susceptor (10) that holds a substrate (1) has a substantially pyramidal shape with a plurality of inclined surfaces, and a rotating shaft (11) is suspended perpendicularly to a base. The bell jar (12) is attached to a tulip-shaped bell jar (12), and is rotatably held in the bell jar (12).
) The source gas is introduced into the reaction chamber (15) from the gas inlet (14) provided in the member (13) that closes the opening at the top of the bell jar (12), and the gas jJI= JJI is output from the outlet (16), and a high frequency coil (17) is disposed around the outer periphery of the bell jar (12). Although an infrared lamp can be used as the heating source, an example using a high frequency coil will be shown here.

The bell jar (12) has a shape in which the outer circumference gradually decreases from the gas inlet (14) side toward the lower gas outlet (16).

In the barrel type vapor phase growth apparatus shown in FIG. ), the bell jar (22) is rotatably held and arranged to cover the bell jar (22), which has a gas inlet (22) in the center of the head.
24), and the outer circumference length in the horizontal direction gradually decreases toward the lower opening, and the raw material gas enters the reaction chamber (2) in the bell jar (22) from the upper gas inlet (24).
5) The gas descends inside the bell jar (22) and is discharged from a member that closes the opening at the bottom of the bell jar (22) or from a gas outlet (26) provided in the base, and a high frequency coil (27) is arranged around the outer periphery of the bell jar (22). This is the configuration that will be used. Although an infrared lamp can be used as the heating source, here we show an example using a high-frequency coil.As mentioned above, the shape of the bell jar (12 x 22) can be adjusted depending on the inclination angle of the susceptor (10 x 20), etc. The special shape according to the invention has the following advantages.

That is, in general, the raw material gas is heated and expands as it goes downward in the conventional cylindrical reaction chamber (5) (see Figure 3), which creates buoyancy and lowers the flow velocity everywhere on the downstream side. turbulence, the concentration of the raw material gas is high on the upstream side and low on the downstream side,
The thickness of the film formed on the downstream substrate tended to be non-uniform, but by creating a reaction chamber with a so-called tapered shape (15 to 25) in which the outer circumferential length is temporarily reduced according to the present invention, the thickness of the film formed on the downstream substrate can be improved. Since the area passing through the tube is reduced, the flow rate becomes faster, and a uniform film can be obtained with less influence of buoyancy.

Note that if the bell jar is made cylindrical and the inclination angle of the susceptor is made gentler, the situation is considered to be relatively similar to the above case, but the shape of the susceptor changes, the holding area of the substrate changes,
This is not preferable because it causes various problems such as a change in gas concentration.

Example Using the barrel type vapor phase growth apparatus shown in Fig. 1, susceptor: hexagonal pyramid diagonal length upper side 250 mm, lower side 280 mm, rotation speed 6/min Bell jar: upper diameter 335 mm, lower diameter 310 mm
, distance between the high frequency coil and the light reflecting structure; 20 to 35 mm
Heating time: 1 hour Heating temperature: 1200°C, reaction time: 30 minutes Semiconductor gas: 5iC14 When vapor phase growth was performed using the apparatus of the present invention under the following conditions, compared to the conventional apparatus in which the bell jar had a cylindrical shape with a diameter of 335 mm, , the formed thin film thickness became uniform, and the film thickness variation was reduced by 10%.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a barrel type vapor phase growth apparatus according to the present invention. FIG. 2 is a vertical 18I-illustration diagram of another vapor phase growth apparatus of the present invention. FIG. 3 is a vertical sectional view of a conventional barrel type vapor phase growth apparatus. 1... Substrate, 10.20... Susceptor, 12.2
2...Quartz bell jar, 14.24...Gas inlet, 15.25...Reaction chamber, 16.26...Gas outlet, I7, 27...High frequency coil.

Claims (1)

[Claims] 1 A substantially pyramid-shaped susceptor with its top facing the gas inlet is placed in a bell jar with gas inlet and outlet ports in the vertical direction, and a chemical reaction such as hydrogen reduction or pyrolysis is used to form a susceptor on the substrate. A barrel-type vapor phase growth apparatus for growing a crystal layer in a vapor phase, characterized in that the reaction chamber is configured with a bell jar whose outer circumference gradually decreases from the gas inlet side toward the lower gas outlet. Vapor phase growth equipment.