JPS5825224A - Vapor growth unit - Google Patents

Abstract

PURPOSE:To rialize a homogeneous growth of a film by a method wherein susceptor-suported semiconductor wafers with some specified distance between them are vertically arranged and a gas supply pipe provided between the tube inner wall and the susceptors injects gas in a direction 10-30 deg. apart from the center of the axis and the supply pipe itself rotates along the tube wall, in a vapor growth unit with a horizontally set reactor tube. CONSTITUTION:In a reaction tube 1 surrounded with a high frequency coil 4, a plurality of semiconductor substrates 3 on susceptors 2 are vertically arranged with some distance between them. In the gap between the wall and the susceptors 2, a gas supplying pipe 6 lies provided with a multiplicity of nozzles and the supply end of the pipe 6 is bent to run along the axis of the tube 1. In the tube wall opposite to the supply pipe 6, a suction port 5 is provided wherethrough the used gas is taken out. In this construction, the direction of the nozzles is so oriented that the injected gas therefrom is 10-30 deg. deviated from the tube central axis, and the supply pipe 6 is caused to rotate along the tube wall. This setup ensures a homogeneous distribution of impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vapor phase growth apparatus, and particularly to a vapor phase growth apparatus with improved film thickness distribution.

When manufacturing semiconductor devices, the epitaxial growth of single crystal silicon (Sl)9 and the vapor phase growth method of growing insulating films and polycrystalline St on the semiconductor substrate surface are important, and there are various types of growth equipment. have been developed, but devices using horizontal reaction tubes are the most commonly used. Figure 11 shows an example of such a growth apparatus. This example is a side sectional view of a reduced pressure vapor phase growth apparatus using a disk susceptor, and the total length is 1.
Susceptors 2 are perpendicularly spaced at 20-m intervals inside a quartz reaction tube 1 with a diameter of 200 m and a semiconductor substrate 3 is held on both sides, and the susceptors 2 are heated by a high-frequency coil 4 outside the tube.
This is a structure in which the semiconductor substrate is heated to a high temperature. The inside of the reaction tube is depressurized by vacuum suction from the gas suction port 5, and the reaction gas is injected from the gas supply capillary 6 to be decomposed on the semiconductor substrate 3 which has reached a high temperature, and is then deposited on the surface thereof.

For example, when trying to epitaxially grow a single crystal S1 on a semiconductor substrate 3, monosilane (Si&) gas, which is a reactive gas, is injected through a large number of injection ports that are thrown into the gas supply capillary 6. However, in order to make the thickness of the epitaxially grown film uniform, the gas supply thin tube 6 injects the reaction gas inside the reaction tube 1 while repeatedly moving from side to side along the upper part of the tube wall. FIG. 2 is an enlarged cross-sectional view of the AA' cross section in FIG. Single-crystal Si is grown while repeatedly moving left and right through the steps shown by broken lines.

The purpose of providing the gas supply thin tube 6 in the longitudinal direction inside the reaction tube and moving it from side to side along the tube wall is, of course, to form a homogeneous grown film, but it does not necessarily ensure satisfactory growth. No membrane was obtained. According to conventional data, for example, there may be a difference in film thickness of 4511 even within one substrate, and even between multiple substrates, the average value of warpage film thickness may be 3μ.
There is a variation from 15 to 15 pa, which is by no means small. The purpose of the present invention is to form a grown film with a more uniform quality using a growth apparatus having such a structure.The feature of the present invention is that it is provided in the reaction tube in the longitudinal direction, and is provided along the shoulder inner wall of the reaction tube. This is a vapor phase growth apparatus with a structure in which the injection direction of the bus injection lower of the gas supply thin tube that supplies the reaction gas while moving inside the tube is constantly deviated by 10 to 30 degrees from the axial center of the reaction tube. This will be explained in detail with reference to 1w.

The pipe diameter of the gas supply thin tube 6 in the example described in Section 1 is 16-,
A large number of injection lowers with a hole diameter of 1-10 mm are provided, and the chart in FIG. 3 shows experimental data for growing the Evita mid-Shall layer by changing the hole directions in various ways. In the figure, the case where the hole direction of the injection lower is directed toward the axial center of the reaction tube is assumed to be 0, and the angle (θ) is 215" and 45° (J3
The data is for the case where the vertical axis is the film thickness, and the horizontal axis is the horizontal position of the reaction tube, which is about 30 mm when held on the screen of the susceptor.
This is a chart showing the film thickness (average value) of a number of semiconductor substrates 3. As is clear from the figure, the film thickness difference is largest when the injection lower is oriented toward the axis center at θ−〇°, and θ
- 匍.

In the case of
The result was that the difference in film thickness was the smallest between No.1 and No.1.

Furthermore, when the film thickness distribution within one semiconductor substrate is I-0°, a 45-film thickness difference occurs as described above, but when θ-90°
In the case of 29Lθ ■ 1411 in the case of 45'', the measurement value with the smallest difference was obtained when the film thickness distribution within the substrate was θ-n, 5@. The heating temperature of the substrate is approximately 900°C, and the S contained in the heating gas is
The results were obtained at tH, gas concentration 2L, gas weight 1°54-, but it is clear that the above-mentioned tendency will occur even if the conditions change, and we conducted a more detailed experiment by changing the injection direction. However, when the angle between 10° and 30° was 22.5°, similar good results were obtained in 10. Therefore, the present invention has a structure in which the injection direction of the injection lower is shifted slightly from the axial center by 2 degrees, and the injection is directed at an angle of 10 to 30''. Fig. 4 shows a growth apparatus according to the present invention. In the cross-sectional view, the injection lower of the gas supply capillary 6 is located 022 from the axial center of the reaction tube.
．． 5. The structure is oriented in the opposite direction, and the injection gas is ejected in the direction of the arrow as the gas supply capillary 6 rotates.

The above description is based on one embodiment, but the gas supply thin tube 6
It is certain that even better results will be obtained if the injection ports are arranged so that they are shifted to both the left and right sides, rather than being shifted to only one direction. In this way, the present invention makes the film thickness uniform within the substrate,
Furthermore, this is a vapor phase growth apparatus that uniformizes the film thickness of a large number of substrates grown at the same time, which naturally results in a uniform impurity concentration distribution, which greatly contributes to improving the yield and quality of semiconductor devices.

It should be noted that the present invention provides a similar effect to a heater-heated growth apparatus that does not use a susceptor, and is applicable not only to epitaxially grown layers but also to phosphosilicate glass films, silicon nitride films, silicon oxide groups, or polycrystalline growth layers. Needless to say, it is also effective when applied to the growth of Si.

[Brief explanation of the drawing]

Figure 1 is a side cross-sectional view of a vapor phase growth apparatus, Figure 2 is a cross-sectional view of a conventional vapor phase growth apparatus, Figures 11 and 3 are graphs of experimental data when the gas injection direction is changed, and Figure 4 is a diagram of the present invention. 1 is a cross-sectional view of a vapor phase growth apparatus according to the present invention. In the figure, 1 is a reaction tube, 2 is a susceptor, 3 is a semiconductor substrate, 4 is a high frequency coil, 5 is a gas suction port, 6 is a gas supply thin tube, and 7 is a gas injection port. Fig. 1 Fig. 2 klε sound tank force'self 1 (tt position Fig. 4 97-

Claims (1)

[Claims] In a vapor phase growth apparatus using a horizontal reaction tube in which a plurality of substrates are arranged perpendicularly to the longitudinal direction of the reaction tube and a film is grown on the surface of the substrate, A gas phase characterized in that the gas injection direction of the gas supply thin tube that supplies the reaction gas while moving inside the tube along the circumferential inner wall of the reaction tube is deviated by 10" to 30 degrees from the axial center of the reaction tube. growth equipment.