JPH0616499B2 - Vapor phase epitaxial growth system - Google Patents

Description

The present invention relates to a vapor phase epitaxial growth apparatus, and more particularly to a vapor phase epitaxial growth apparatus having a vertical reaction tube.

[Conventional technology]

FIG. 6 shows a conventional vapor phase epitaxial growth apparatus. Conventionally, this type of vertical vapor phase epitaxial growth apparatus holds single crystal substrates 24 in a substrate holder 23 so as to be stacked horizontally at a certain interval, and under reduced pressure, the resistance heating furnace 25 keeps the temperature at about 900 ° C to 1200 ° C. Heat the substrate 2
The surface of No. 4 was made to grow epitaxially by introducing a silane-based gas such as dichlorosilane (SiH ₂ Cl ₂ ), hydrogen (H ₂ ) and a doping gas. The reaction tube has a double structure, and the outer tube 20 maintains a vacuum and rotates the single crystal substrate 24.
A reaction gas is supplied to the inner tube 21 through a nozzle 26, and the reaction gas is exhausted through a gas exhaust hole 27 provided uniformly over the entire circumference of the cylindrical surface of the inner tube 21.

[Problems to be solved by the invention]

In the conventional vapor phase epitaxial growth apparatus described above, the gas exhaust holes 27 provided for exhausting the reaction gas are evenly distributed on the cylindrical surface of the inner pipe 21, so that the reaction gas is exhausted in all directions. Therefore, there is a drawback that the flow of the gas ejected from the nozzle 26 is disturbed.

In order to grow a good quality epitaxial film having a uniform film thickness and no defects in the vapor phase growth method, it is basically important that the reaction gas flow is in a uniform laminar flow state on the substrate wafer 24.

The vertical vapor phase epitaxial growth system has the advantage of being able to perform epitaxial growth on a large number of wafers at a time by batch processing, but it is difficult to make the flow on each wafer a uniform laminar flow state, and the film thickness uniformity is poor with conventional systems. However, there is a defect that a defect occurs and it is difficult to obtain a high-quality epitaxial film.

[Means for solving problems]

The vapor phase epitaxial apparatus of the present invention comprises a vapor phase having an outer reaction tube, an inner reaction tube having a gas discharge hole on its wall surface, a substrate holder provided in the inner reaction tube and a nozzle having a reaction gas discharge hole. In the epitaxial growth apparatus, the gas discharge hole provided on the wall surface of the internal reaction tube is provided only on the wall surface of the internal reaction tube on the side facing the nozzle and the substrate holder.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view of the first embodiment of the present invention. This apparatus includes a pedestal 3 for supporting the apparatus, a reaction tube having a double tube structure including an outer tube 1 and an inner tube 2, a substrate holder 4 for holding a single crystal substrate 5, a resistance heating furnace 6 and a reaction gas. It is composed of a supply nozzle 7.

The reaction gas is ejected from the nozzle 7 and is exhausted from the exhaust port 9 through the gas exhaust hole 8 provided in the cylindrical surface of the inner pipe 2.
This gas exhaust hole does not exist on the nozzle 7 side of the cylindrical surface of the inner pipe 2 as shown in the sectional view of the inner pipe AA ′ in FIG. 2, but is provided only on the opposite side in a 180 ° region. There is.

Therefore, the flow of the reaction gas becomes smooth, and the concentration of the reaction gas becomes uniform over the entire surface of the single crystal substrate 5, so that a uniform epitaxial film can be formed in the substrate surface.

The following is an example of epitaxial film growth according to this embodiment.
100 pieces of silicon single crystal substrates with a diameter of 150 mm are set on the substrate holder 4 at intervals of 8 mm, and the substrate holder 4 is rotated at a rotation speed of 10 revolutions per minute (10 rpm) to bring the temperature inside the reaction tube to 1100 ° C. did. 20 H ₂ from nozzle 7
/ Min, SiH ₂ Cl ₂ 1 / min, pH ₃ 3 ml / min
At a pressure of 5 torr and 5 μm on the silicon single crystal substrate 5.
Of silicon epitaxial film was grown.

This result will be described in comparison with the result when a silicon epitaxial film is grown by the conventional vapor phase epitaxial growth apparatus shown in FIG. 6 under the same growth conditions.

FIG. 3 shows a silicon epitaxial film thickness distribution in a wafer when the conventional growth apparatus and the growth apparatus of the present invention are used. When the conventional growth apparatus is used, the thickness distribution is thin in the peripheral portion of the silicon substrate and is thick in the central portion, but the growth apparatus of the present invention significantly improves the thickness distribution, and a good thickness distribution within ± 4% is obtained. Was obtained. Also, the resistance distribution in the wafer plane was similarly improved.

Further, the film thickness distribution and the resistance distribution between the wafers could be suppressed within ± 4%. In addition, a MOS diode is formed on the epitaxial film grown in this way, and MO
When the carrier lifetime was measured by the S C-t method, a value of 5 × 10 ⁻³ sec or more was obtained for any wafer, and the value of the normal bulk silicon wafer measured as a reference for comparison was 1 Since it was × 10 ^-3 sec, it can be said that the crystallinity of the epitaxial film is sufficiently good.

FIG. 4 is a sectional view showing a second embodiment of the present invention and corresponds to the sectional view taken along the line AA ′ of FIG. 1 in the first embodiment.

In this embodiment, unlike the above-described first embodiment, the region where the gas discharge holes 8 are provided is within the range of 30 ° when viewed from the center of the inner tube 2 on the side opposite to the nozzle 7. is there. When a silicon epitaxial film was grown under the same conditions as in the first embodiment, a film thickness distribution within the wafer as shown in FIG. 5 was obtained. In the second embodiment, the growth rate is ⅓ as compared with the first embodiment, and three times time is required to obtain the same film thickness, but the film thickness within ± 2% There is an advantage that a distribution can be obtained.

In the above-mentioned first and second embodiments, the nozzle holes faced the wafer, but similar results were obtained even if the nozzle holes were turned in the opposite direction. In addition, although the number of nozzles 7 is one in the first and second embodiments, the number of nozzles 7 is two and three.
Good results were obtained for the book as well. in this way,
By not providing the gas discharge hole 8 on the wall surface of the inner tube in the vicinity of the nozzle 7, good results could be obtained regardless of the direction of the nozzle hole and the number of nozzles 7.

〔The invention's effect〕

As described above, according to the present invention, the gas discharge hole 8 provided on the wall surface of the inner tube 2 of the vapor phase epitaxial growth apparatus is only on the semicircular wall surface opposed to the nozzle 7 via the central axis of the inner tube 2. The reaction gas flow path is controlled so that the reaction gas is uniformly supplied over the entire surface of the single crystal substrate 5. As a result, there is an effect of improving the film thickness distribution, the resistance distribution, and the crystallinity of the epitaxial film.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a silicon vapor phase epitaxial growth apparatus of the present invention, and FIG. 2 is an inner tube A of the first embodiment of the present invention.
-A 'line sectional view, FIG. 3 is a diagram showing the film thickness distribution of the silicon epitaxial film of the first embodiment, and FIG. 4 is the AA' line of the inner tube of the second embodiment of the present invention. Sectional view, Figure 5 is second
FIG. 6 is a view showing the film thickness distribution of the silicon epitaxial film of the embodiment, and FIG. 6 is a sectional view of a conventional vapor phase epitaxial growth apparatus. 1 ... Outer tube, 2 ... Inner tube, 3 ... Stand, 4 ... Substrate holder, 5 ... Single crystal substrate, 6 ... Resistance heating furnace, 7 ... Nozzle, 8 ... Gas discharge hole, 9 ...... Exhaust port, 20 …… Outer tube, 21 …… Inner tube, 22 …… Stand, 23 …… Substrate holder, 24 …… Silicon single crystal substrate, 25 …… Resistance heating furnace, 26 …… Nozzle, 27 ・ ・ ・… Gas outlet, 28 …… exhaust port.

Claims (2)

[Claims] 1. A vapor phase epitaxial growth apparatus having an outer reaction tube, an inner reaction tube having a gas discharge hole 6 on its wall surface, a substrate holder provided in the inner reaction tube and a nozzle having a reaction gas discharge hole. The vapor phase epitaxial growth apparatus, wherein the gas discharge hole provided on the wall surface of the internal reaction tube is provided only on the wall surface of the internal reaction tube on the side facing the nozzle and the substrate holder. . 2. The inner reaction tube has a circular cross-sectional shape, and a gas discharge hole provided in a wall surface of the inner reaction tube has the inside on a side facing the nozzle and the central axis of the inner reaction tube. The vapor phase epitaxial growth apparatus according to claim 1, wherein the gas discharge hole is provided only on an anti-circumferential wall surface of the reaction tube.