JPS61186288A - Apparatus for vapor-phase epitaxial growth of silicon carbide compound semiconductor - Google Patents

Abstract

PURPOSE:To uniformize the film thickness distribution, and to improve the uniformity of a film, by placing a square reaction tube and a susceptor having specific form in a round reaction tube having coolable structure, and enabling the uniform flow of the reaction gas at the upper layer of the substrate crystal. CONSTITUTION:An aquare reaction tube 31 is placed in a coolable round reaction tube 41 near the part where the substrate crystal 11 is to be placed. The reaction tube 31 has rectangular cross-section, and has a bottom part inclined upward toward the flowing direction of the reaction gas. A susceptor 20 for holding a substrate crystal 11 is placed downstream side of the reaction tube 31, and the bottom face in the susceptor 20 is positioned to the same level as the bottom in the reaction tube 31. The flow of the reaction gas can be uniformized by the above apparatus without being disturbed with the susceptor 20, and a uniform film can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vapor phase growth apparatus for epitaxially growing a silicon carbide compound semiconductor crystal on a large substrate crystal with good uniformity.

[Conventional technology]

Conventionally, as a vapor phase epitaxial growth apparatus for silicon carbide compound semiconductors, a water-cooled round reaction tube 4 is used as shown in FIG.
A structure is used in which a susceptor 20 is placed directly inside the susceptor 1, and a substrate crystal to be epitaxially grown is placed on top of the susceptor 20 (IEICE technical research report 5SD82-1).
67).

[Problem that the invention seeks to solve]

However, in this structure, since the susceptor 20 is placed directly inside the round reaction tube 41, the flow of the reaction gas is disturbed at the susceptor 20, making it impossible to epitaxially grow a silicon carbide compound semiconductor with good uniformity on the substrate crystal. There was a drawback.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus capable of eliminating such conventional drawbacks and epitaxially growing a silicon carbide compound semiconductor crystal on a large substrate crystal with good uniformity.

[Means for solving problems]

The present invention provides a vapor phase epitaxial growth apparatus for a silicon carbide compound semiconductor, in which a coolable round reaction tube has a rectangular cross section, and the bottom thereof is located at least in the vicinity of the installation part of a substrate crystal to be epitaxially grown, and the bottom thereof is located in the downstream direction of the flow of a reaction gas. Install a rectangular reaction tube that is facing higher,
Further, on the downstream side of the rectangular reaction tube, a susceptor for mounting a substrate crystal, which has a cavity inside and both ends of the cavity are open to the flow direction of the reaction gas, is arranged so that the bottom surface of the susceptor has a cavity inside the rectangular reaction tube. This is a vapor phase epitaxial growth apparatus for a silicon carbide compound semiconductor, characterized in that the wall surface of the susceptor is coated with silicon carbide.

[Effect]

First, a square reaction tube with a rectangular cross section is installed near the location where the substrate crystal to be epitaxially grown is placed.
A susceptor is provided downstream of the rectangular reaction tube and has a hollow interior and both ends of the cavity are open to the flow direction of the reaction gas. By installing the substrate crystal to be epitaxially grown on the inner bottom surface of the susceptor so that they are on the same plane, the flow of the reaction gas is not disturbed by the susceptor, so the flow of the reaction gas in the upper layer of the substrate crystal is improved. As a result, a silicon carbide compound semiconductor epitaxial film with good uniformity can be obtained. Furthermore, in order to increase the uniformity of the flow of the reaction gas, it is necessary not only to make sure that the inner bottom surfaces of the square reaction tube and the susceptor are on the same plane, but also to make sure that the inner bottom surfaces of the square reaction tube and the susceptor are on the same plane. It is preferable to have a structure in which the upper surface and the upper surface are also on the same plane.

Next, by raising the bottom of the rectangular reaction tube toward the downstream direction of the flow of the reaction gas, the amount of the grown film supplied onto the substrate crystal becomes constant with respect to the flow direction. The film thickness distribution of the film can also be made constant. The angle of the side square reaction tube is preferably in the range of 2 degrees to 20 degrees. If it is less than 2 degrees, the epitaxial film in front of the substrate crystal will be too thick compared to that in the rear, and if it is more than 20 degrees, the epitaxial film in the rear of the substrate crystal will be too thick compared to that in front, which is not preferable.

Furthermore, by using a susceptor that is hollow inside and whose walls are coated with silicon carbide, and by placing the substrate crystal inside it, the part that comes into contact with the reaction gas near the substrate crystal is the inner surface of the susceptor, and the crystal growth temperature is is the same as Therefore, the reaction gas reacts on the wall surface of the susceptor and generates silicon carbide, but since the wall surface of the susceptor is coated with silicon carbide, this silicon carbide only thickens the silicon carbide coating layer, and the silicon carbide produced on the wall surface There is no falling off from the substrate.Therefore, there is no falling material on the substrate crystal, and a uniform growth phase can be obtained.

In addition, using only the square reaction tube is weak in strength and cannot reduce the pressure inside the reaction tube, but by providing a round reaction tube on the outside, it is possible to reduce the pressure inside the reaction tube, and the gas inside the reaction tube can be reduced. This makes it possible to quickly replace the oil and grow under reduced pressure.

The epitaxial growth temperature of silicon carbide is a high temperature of 1,300°C or higher, but by making the round reaction tube have a structure that can be water-cooled, it is possible to prevent deterioration of the reaction tube. The radiation of heat to the outside is suppressed, and the amount of heat coming out of the reaction tube is extremely reduced.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, the cross section 1i [
Yes, CB) is a prisoner (7) a a' arrow view, (C) ii
It is a b b' arrow view of the prisoner. Figure 1 prisoner ~ (at 0,
A square reaction tube 31 is placed inside a round reaction tube 41 equipped with a water cooling chamber 45 on the outside of the tube. The cooling water flows into the water cooling chamber 45 from the cooling water port 43 and flows out from the cooling water outlet 44 . The rectangular reaction tube 31 has a rectangular cross section rearward from the portion 33 in (4) as shown in (B), and the bottom thereof is inclined upward toward the downstream direction of the flow of the reaction gas. ,
It has a structure in which a susceptor 20 can be installed at the rear end.

The inside of the +j flood pipe 20 is hollow, and both ends of the hollow are open to the flow direction of the reaction gas. A susceptor 20 having a cavity and a rectangular cross section is introduced into the square reaction tube 31, and the bottom, side and top surfaces of the susceptor 20 are respectively connected to the bottom, side and top of the inside of the square reaction tube 31. The susceptor 20 is installed inside the susceptor so as to form the same plane. The susceptor 20 is made of graphite, and its wall surface is coated with silicon carbide. A substrate crystal 11 to be epitaxially grown is placed on the inner bottom surface of the susceptor 20 through the open rear end.

SiH4, C3 and taX gases are introduced through the reaction gas introduction pipe 32, and a reaction gas is introduced through the gas introduction pipe 42. Heating is performed by introducing high frequency power from the high frequency coil 50.

In Figure 1, a round reaction tube 4 with an internal diameter of 150H
A square reaction tube 31 with an internal width of 100 m and a bottom inclined at 5 degrees and rising toward the downstream direction, and a rectangular reaction tube 31 with an internal width of 100 m and an internal bottom surface A susceptor 20 having an inclination of 5 degrees and rising toward the downstream direction is used, and is arranged so that the distance between the top surface and the bottom surface inside the susceptor 20 is 15 degrees at (O), and as a substrate crystal 11. , 81 single crystal with a diameter of 3 inches was used, and the (100) plane was used as the plane orientation of the substrate.

After introducing the Sl single crystal substrate 11 and before growth, a rotary vacuum pump was used to exhaust the air component in the reaction tube from the rear open end. Thereafter, hydrogen was introduced through the gas introduction pipes 32 and 42 to fill the inside of the reaction tube with hydrogen at atmospheric pressure.

8LH4 and C1H are used as reaction gases, and hydrogen gas is introduced as a carrier gas through the reaction gas introduction pipe 32. During growth, hydrogen, S, and
The total flow rate of iH4, C, H, was 517mlx. Furthermore, hydrogen was introduced at 31/m through the gas introduction pipe 42 throughout the entire process. First, only hydrogen was flowed through the reaction gas introduction pipe 32, the substrate crystal temperature was maintained at 1200° C. for 10 minutes, and 81 substrates were cleaned. Next, from the reaction gas introduction pipe 32, the concentration is 0.0.
8 mol of C3H was introduced, and the substrate crystal temperature was maintained at field temperature for 1 minute to form a silicon carbide buffer layer on the Si substrate. Thereafter, 5 inches of C3H with a concentration of 0.03 molar and 0.01 molar of C3H were simultaneously introduced from the reaction gas introduction pipe 32, and the substrate crystal temperature was maintained at 1350° C. for 3 hours to grow crystals of silicon carbide.

As a result of the growth as described above, there was no falling object on the substrate crystal even after three hours of growth. Further, the grown film obtained as described above is epitaxially grown on the St substrate, and consists only of a silicon carbide layer over the entire surface of the substrate, and the film thickness distribution is 14.5±0. An excellent uniformity of 5 μm was obtained.

Furthermore, the temperature at a distance of 10 cIIL from the outer surface of the water-cooled round reaction tube was a maximum of 40° C. during growth, and the amount of heat released to the outside of the reaction tube was extremely small.

〔Effect of the invention〕

As described in detail above, according to the present invention, an epitaxial film of a silicon compound semiconductor with good uniformity can be obtained, and a uniform epitaxial growth layer with a uniform film thickness distribution and no falling particles on the substrate crystal can be obtained. It has the effect that can be obtained.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an embodiment of the present invention;
A' arrow view, b b' arrow view of (C) ii, and FIG. 2 are cross-sectional views showing the conventional method. 11... Substrate crystal, 20... Susceptor, 31...
・Square reaction tube, 32...Reaction gas introduction tube, 33...
Portion where the cross section begins to become square, 41...Water-cooled round reaction tube, 42...Gas introduction tube, 43...Cooling water inlet,
44...Cooling water outlet, 50...High frequency coil. Patent applicant: NEC Corporation Patent attorney: W, Shin'4
．． Figure 1 (A) 1, tail plate system 20: susceptor 31゛ square reaction tube 41, waterside round reaction tube Figure 1 (B (C)

Claims (1)

[Claims] (1) In a vapor phase epitaxial growth apparatus for silicon carbide compound semiconductors, at least the vicinity of the installation part of the substrate crystal to be epitaxially grown in the coolable round reaction tube has a rectangular cross section and the bottom is oriented in the downstream direction of the flow of the reaction gas. A rectangular reaction tube that had once been raised is installed, and further, on the downstream side of the rectangular reaction tube, a substrate crystal is mounted, which has a cavity inside, and both ends of the cavity are open to the flow direction of the reaction gas. A silicon carbide compound semiconductor gas susceptor, characterized in that a susceptor is installed so that its inner bottom surface is flush with the inner bottom surface of the square reaction tube, and the wall surface of the susceptor is coated with silicon carbide. Phase epitaxial growth equipment.