JPS63181414A - Apparatus for forming semiconductor film - Google Patents

Abstract

PURPOSE:To prevent a reaction gas from producing a deposit on the inside of a reaction vessel which would inhibit epitaxy to be performed therein and to enable temperature to be increased rapidly, by providing a wafer table formed of a material having desirable infrared absorption properties and desirable heat conductivity and an infrared radiation source outside the reaction vessel so as to be opposed to the wafer table. CONSTITUTION:Infrared rays radiated from an infrared lamp 3 are transmitted by the outer wall of a reaction vessel 1 and absorbed by a wafer table 2 whereby the table is heated uniformly. A thermo couple 9 detects a temperature of the heated table and power supply to the infrared lamp 3 is control led according to the output from the thermo couple 9, so that the temperature of the table 2 is held at a certain level and a wafer 4 is heated at fixed temperature. Further, since the reaction vessel 1 is formed of quartz or the like, no deposit is formed thereon by a reaction gas under such working conditions and, therefore, epitaxy within the vessel is not inhibited thereby. The temperature can be increased rapidly by increasing the capacity of the infrared lamp 3 according to a heat capacity of the material table 2. Further, the temperature can be lowered rapidly by decreasing the heat capacity of the table 2 according to an amount of supply of the reaction gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for forming a semiconductor film by low pressure vapor phase growth.

[Conventional technology]

Vapor phase deposition (hereinafter referred to as CvD) is generally used in semiconductor development processes, but in particular when forming a semiconductor film by low pressure CVD, for example, DC-7000
E-type silicon epitaxial single crystal growth apparatus (manufactured by Kokusai Denki KK) or the apparatus disclosed in Japanese Patent Application Laid-Open No. 58-95748 is used; in the former, quartz or the like is used. A susceptor was provided to place the sample on the bottom of the hemispherical bell jar, and a high-frequency current was passed through a coil installed below the susceptor. Using heat generated by the eddy current generated in the susceptor, the sample was placed on the top surface of the susceptor. The sample is heated, the pressure inside the bell jar is reduced, and a reaction gas is supplied into the bell jar.

In the latter case, a susceptor made of a material with good infrared absorption and thermal conductivity, such as carbon, is provided inside the metal container, and a material with infrared transmission, such as quartz, is provided at the bottom of the container. The system uses an infrared lamp to heat the scissor receptor through the window, heats the sample placed on it, simultaneously reduces the pressure in the container, and supplies the reactant gas into the container. ing.

Note that these devices are used to raise and lower the temperature at a relatively high speed when epitaxially growing a semiconductor film. The film is epitaxially grown.

[Problem that the invention seeks to solve]

However, in the former case, the temperature in the bell jar is low compared to the temperature increase in the susceptor, and the reaction gas comes into contact with the susceptor and decomposes on the high-temperature sample and the susceptor, and then deposits in the form of a film. During epitaxial growth of a semiconductor film, deposits re-evaporate during cleaning and cooling of the semiconductor surface of a substrate, contaminating the surface of the substrate and inhibiting epitaxial growth.

Furthermore, since a high-frequency electromagnetic field is used, in a reduced-pressure atmosphere, the reaction gas is ionized by the high-frequency electromagnetic field and a plasma state is generated, resulting in a problem that the controllability of the reaction situation by the reaction gas deteriorates rapidly.

On the other hand, in the latter case, deposits adhere to the inside of the container as described above, inhibiting epitaxial growth, and in order to reduce the pressure inside the container, the thickness of the window material is set to have sufficient strength against the pressure difference between the inside and outside of the window. If the window is made larger, the weight will increase and the parts that attach to the container must be made stronger, which means that the window will be made smaller. This causes problems such as a decrease in the transmission area and a decrease in heating efficiency.

[Means for solving problems]

In order to solve the above-mentioned problem, the present invention is constructed by the following means.

That is, in a semiconductor film forming apparatus using a reduced pressure vapor phase growth method, a cylindrical reaction vessel made of a material that is transparent to infrared rays and has properties that prevent deposits from reacting gas from adhering to it; It is equipped with a sample stage made of a material with good infrared absorption and thermal conductivity, and an infrared radiation source provided outside the reaction vessel to face the sample stage.

[Effect]

Therefore, the sample stage is heated by the infrared rays from the infrared radiation source through the reaction vessel, which also heats the sample on the sample stage, and prevents deposits caused by the reaction gas from adhering into the reaction vessel.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to figures showing examples.

Figure 1 is a side view showing the structure of the cylindrical material, which is made of materials such as quartz (Sigh) glass and sapphire, which have properties that prevent deposits from reacting gas from adhering to them, and which have infrared transmittance. A reaction vessel 1 is provided, and a sample stage 2 made of a material with good infrared absorption and thermal conductivity such as hegraphite carbon is provided in the vessel 1, and a sample stage 2 made of a material with good infrared absorption and thermal conductivity such as hegraphite carbon is provided below the sample stand 2 and outside of the reaction vessel 1. A tubular infrared lamp 3 is provided opposite the sample stage 2 as an infrared radiation source.

In addition, a sample 4 such as silicon (St) is placed on the sample stage 2, and an exhaust pipe 5 is airtightly connected to the right side of the reaction vessel 1, and a vacuum pump is connected to the right side of the reaction vessel 1. While the pressure inside the reaction vessel 1 is reduced at 6, a gas source 8 is connected to the left side of the vessel 1 via a pipe T connected in an airtight manner, and the reaction gas is reacted with this gas source 8. It is to be supplied into the container 1.

In addition, a horizontal hole is drilled on the side of the sample stage 2, and a thermocouple 8 is inserted into this.
The temperature of the infrared lamp 3 is detected and the power supply status to the infrared lamp 3 is controlled.

Therefore, the infrared rays emitted from the infrared lamp 3 pass through the outer wall of the reaction vessel 1 and are absorbed by the sample stage 2, heating it evenly. Since the power supplied to the infrared lamp 3 is controlled by the detection output and the temperature of the sample stage 2 is maintained constant, the sample 4 is heated to a constant temperature accordingly.

However, in a reduced pressure atmosphere, the temperature of the sample stage 2 and the sample 4 will be different, but in a steady state, the temperature difference is constant and the force is constant. It is sufficient to make the correction.

In addition, since the reaction vessel 1 is made of quartz or the like, deposits caused by the reaction gas do not adhere under the operating conditions.
This does not inhibit epitaxial growth.

That is, for example, the substrate temperature of sample 4 is 400°C, the pressure of the reaction gas GeHa is about 0.3 torr, and Ge
When epitaxial growth is performed, no (Ge) is deposited above 810°.

Note that this is an S1 film formation using a reaction gas of 5izHs,
GaA using reactive gases Ga(CHs)s and AsHs
The same applies to the formation of s.

Therefore, high-speed heating can be achieved by increasing the capacity of the infrared lamp 3 according to the heat capacity of the sample stage 2, and by decreasing the heat capacity of the sample stage 2 according to the amount of reactant gas supplied. , high-speed cooling temperature can be controlled.

According to the experimental example, the dimensions are 20α×20crIM×1.5c
Using a sample stage 2 made of graphite carbon with rn1SiC code, the supply rate of reaction gas H2 was 31/rm,
Under conditions of a pressure of 5 torr, the temperature of the sample stage 2 can be lowered from 700° C. to 400 t within 10°.

Furthermore, under the above conditions, when the temperature of the sample stage 2 is kept constant at 700°C, the temperature of the sample 4 is about 600°C, and after the temperature of the sample stage 2 is kept constant, the temperature of the sample 4 is about ±1. ℃
The required time of about 2i or less was sufficient to reach a constant value.

On the other hand, when a cylindrical quartz tube is used as the reaction vessel 1, a wall thickness of about 5 mm is sufficient for strength, it is easy to manufacture, and airtight connection with the exhaust pipe 5 and piping 7 is possible. It is easy to use, and the length of the seal can be made relatively short due to the O-ring at the connection part, which improves airtightness.The connection part can also be separated from the infrared lamp 3, and the airtightness can be improved by heating. The decline can be prevented.

In addition, since deposits caused by the reaction gas do not adhere, epitaxial growth is not inhibited, and the infrared transmittance of the reaction vessel 1 does not decrease, the heating efficiency by the infrared lamp 3 is always good.

In addition, when it becomes necessary to clean the reaction vessel 1, the shape of the reaction vessel 1 is simple, and it is easy to remove it from the exhaust pipe 5 and piping 7 and wash it together with the sample stage 2 with acid etc. be.

Figure 2 shows an example of the arrangement of infrared radiation sources along the X-Y line in Figure 1.
This is a cross-sectional view. In this case, rod-shaped heaters 11 are used as infrared radiation sources, and a plurality of heaters are arranged in parallel to the outside of the lower part of the reaction vessel 1, facing both sides and the lower part of the sample stage 2. , and these are surrounded by a reflecting plate 12 to make the vertical surface temperature distribution of the sample stage 2 uniform.

Further, in this case, a plurality of horizontal holes are made in the sample stage 2, and thermocouples 9a to 9C are inserted into each hole, and each heater 11 is controlled by these.

Therefore, in this case, it is possible to freely increase the total capacity of the heater 11, which facilitates high-speed heating.

On the other hand, when the sample 4 has infrared transmittance, an infrared lamp 3 is disposed on the upper outer side of the reaction vessel 1 so as to face the sample stage 2, and heating can also be performed from the upper surface side.

Furthermore, if it is necessary to raise the temperature of the sample stage 2 on the reactant gas supply side to remove the cooling effect of the reactant gas, use a 10-gen lamp as an infrared radiation source and change the distribution density of the heater wire. Alternatively, a plurality of heaters 11 and the like may be arranged along the outer periphery of the cross section of the reaction vessel 1, and the power supplied thereto may be individually controlled.

Therefore, with a simple and inexpensive configuration, an apparatus suitable for low-pressure CVD method that does not inhibit epitaxial growth and can freely raise and lower the temperature at high speed has been realized. , maintenance becomes extremely easy.

However, the cross-sectional shape of the reaction vessel 1 may be elliptical or angular, various types of infrared radiation sources can be used, and the SIC code of the sample stage 2 is omitted because it is a container for cleaning. Various modifications are possible, such as using other temperature sensors in place of the thermocouples 9, 9a to 9c.

〔Effect of the invention〕

As is clear from the above description, the present invention has a simple and inexpensive configuration, and deposits caused by the reaction gas do not adhere to the inside of the reaction vessel, thereby preventing epitaxial growth from being inhibited, and at the same time reducing heating efficiency due to infrared rays. Since there is no heat loss, the temperature can be raised and lowered at high speed, and a large number of wafers etc. can be processed at once, remarkable effects can be obtained in the formation of semiconductor films by the low pressure CVD method.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, FIG. 1 is a side view showing the configuration, and FIG. 2 is an X-Y line in FIG.
lifr page diagram. 1...Reaction container, 2...Fist/sample stand, 3...Infrared lamp, 4...Sample, 11...Heater.

Claims (1)

[Claims] A semiconductor film forming apparatus using a reduced pressure vapor phase growth method includes a cylindrical reaction vessel made of a material that is transparent to infrared rays and has properties that prevent deposits from reacting gas from adhering to it; 1. A semiconductor film forming apparatus comprising: a sample stage made of a material with good properties and thermal conductivity; and an infrared radiation source provided outside the reaction vessel to face the sample stage.