JPH0940491A - Method for growing semiconductor crystal film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly simplify equipment by eliminating the need for a pressing gas and to obtain crystal films having the quality identical to the quality obtain able when the films are formed by a two-flow MOCVD method. SOLUTION: The mounting surfaces of substrates S1 , S2 are disposed to face each other. Susceptors 2, 3 are arranged to face each other above and below apart a required spacing. A nozzle 4a of reactive gases G is arranged to face the spacing between both susceptors 2 and 3. While the susceptors 2, 3 are kept rotated, the substrates S1 , S2 are heated and the reactive gases are passed between the two susceptors 2 and 3 from the nozzle 4a, by which the crystal films are grown on the surfaces of the substrates S1 , S2 without using the pressing gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a semiconductor crystal film by passing a reaction gas through the surface of a substrate.

[0002]

2. Description of the Related Art FIG. 3 discloses a crystal film grown on the surface of a substrate, which is disclosed in Japanese Patent Laid-Open No. 4-164895, in which a reaction gas is flowed along the surface of the substrate while a pressure gas is flowed perpendicularly to the substrate. let a schematic diagram showing a preferred state of the method of growing a nitrogen compound semiconductor crystal film according to so-called two-flow -MOCVD method, reference numeral 11 is a susceptor, S _1, S ₂ denotes a substrate.

The susceptor 11 is rotatably supported at its central portion so as to be rotatable in the direction of the arrow, and its surface is substantially flush with the surface of the susceptor 11 in the recesses 11a and 11b formed in the surface thereof. Substrates S ₁ and S ₂ are mounted.

G ₁ is a reaction gas composed of a mixed gas of trimethylgallium (TMG) gas, H ₂ gas, N ₂ gas, NH ₃ gas, etc., and is parallel to the surface of the susceptor 11 on one side of the susceptor 11. Is blown out from the nozzle installed in
_They are distributed along the surfaces of the susceptor 11 and the substrates S ₁ and S ₂ .

G₂Is N₂, H₂Pressing gas consisting of gas etc.
Yes, susceptor 11 and substrate S₁, S ₂Against the surface of
It is shed in the direction orthogonal to this.

The pressing gas G ₂ is mainly used for the following purpose. That is, for example, GaN, InGaN, A
Since the growth of the crystal film of the III-V group compound semiconductor containing N such as lGaN usually proceeds at a high temperature of 700 ° C. or higher, for example, 1000 ° C. or higher, thermal convection occurs on the susceptor 11 and the reaction gas G ₁ is susceptor 11 surface, to show a tendency to flow in the upward away from the substrate S _1, S ₂ surface other words, since the intact results in insufficient reaction gas supply amount, reaction gas G ₁ by a pressing gas G ₂ The susceptor 1
(1) It is to eliminate the reaction gas shortage on the surfaces of the substrates S ₁ and S ₂ by pressing on the surface side.

That is, in the two-flow MOCVD method, when the reaction gas G ₁ is caused to flow along the surfaces of the susceptor 11 and the substrates S ₁ and S ₂ at a predetermined flow velocity, the reaction gas G ₁ is generated by the high temperature susceptor 11. Due to the heat convection, as the distance from the nozzle increases, it tends to separate from the surfaces of the susceptor 11 and the substrates S ₁ and S ₂ and rise, but the pressing gas G ₂
The susceptor 11, flowing in a direction perpendicular to the surface of the substrate S _1, S _2, susceptor 11, the substrate S _1, away from the surface of S _2, the reaction gas G ₁ a susceptor 11 to be Ukiagaro,
The contact area between the reaction gas G ₁ and the substrate S _1, S ₂ by pressing toward the surface side of the substrate S _1, S ₂ is increased, thereby achieving a promotion of the reaction.

[0008]

By the way, in such a conventional growth method, the pressing gas G ₂ needs to flow over substantially the entire surfaces of the substrates S ₁ and S _2. Therefore, as the number of substrates increases, a large amount of pressing gas is generated. There is a problem that G ₂ is required, the pressure gas supply nozzle facility becomes large, and the running cost becomes high.

The present invention has been made in view of the above circumstances, and an object thereof is to simplify the facility by eliminating the need for a pressing gas, and to perform high-quality film formation efficiently with a small apparatus. Another object of the present invention is to provide a method for growing a semiconductor crystal film that enables cost reduction.

[0010]

A method for growing a semiconductor crystal film according to a first invention is a method for growing a semiconductor crystal film on a substrate while using a reaction gas while heating the substrate. It is characterized in that a pair of opposed members facing each other are provided, a substrate is mounted on at least one of the opposed surfaces, and a reaction gas is allowed to flow between the opposed surfaces.

When the extending direction of the gap between the both facing surfaces is the lateral direction, the substrate is preferably mounted on at least the upper facing surface in consideration of the direction of thermal convection.

Further, when the extending direction of the gap between the both facing surfaces is the lateral direction and the substrate is mounted on the both facing surfaces, the flow of the reaction gas is taken into consideration in consideration of the direction of thermal convection. It is preferable to be made from the central lower position between.

Further, in order that the reaction gas reaches the substrate more uniformly, it is preferable that the facing member holding the substrate rotates.

Further, in order to obtain uniform film growth on the surface of the substrate, it is desirable to inject the reaction gas in parallel to the substrate.

Further, it is suitable for growing a semiconductor crystal film of a nitrogen compound such as GaN, InGaN and AlGaN.

In the method for growing a semiconductor crystal film according to the second aspect of the invention, the extending direction of the gap between the opposing surfaces is the vertical direction, and the reaction gas is passed from below between the opposing surfaces. It is characterized by

The method for growing a semiconductor crystal film according to a third aspect of the invention is characterized in that the reaction gas is blown from one or a plurality of nozzles between the opposing surfaces.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to the drawings showing the embodiments thereof. (Embodiment 1) FIG. 1 is a schematic side view showing an embodiment of a method for growing a semiconductor crystal film according to the present invention, in which 1 is a reaction tube, 2 and 3 are susceptors constituting a pair of opposing members, Reference numeral 4 denotes a reaction gas supply pipe, and S ₁ and S ₂ denote substrates.

The reaction tube 1 is constructed by fitting end plates 1b and 1c to both ends of a cylindrical body 1a made of quartz and capable of seeing through.
The inside can be set to an appropriate degree of vacuum. As shown in FIG. 2 (a), a pair of susceptors 2 and 3, which are opposed to each other at a predetermined interval (1 to 10 mm), are axially supported by support arms at the center of the inside of the reaction tube 1. It is installed in the state.

The susceptors 2 and 3 are each formed in a disc shape,
Recesses 2a, 3 into which the substrates S ₁ , S ₂ are fitted are provided on the respective facing surfaces.
Each has a.

The reaction gas supply pipe 4 is introduced from one side of the reaction tube 1 through the end plate 1b, and the nozzle portion 4a at the tip thereof is located on one side of the susceptors 2 and 3 between the facing surfaces. It faces almost the center of the gap.

An exhaust pipe 5 having a diameter larger than that of the reaction gas supply pipe 4 is provided at the center of the opposite end plate 1c.

Reference numeral 6 denotes a heating coil, which is located at a position facing the area where the susceptors 2 and 3 are disposed, and is a cylindrical body 1 of the reaction tube 1.
It is arranged concentrically with the outer periphery of a.

Each of the susceptors 2 and 3 is pivotally supported by a support arm at the center of the back surface thereof, and can be horizontally rotated in the same direction or in the opposite direction by a drive source (not shown).

In the first embodiment, the substrates S ₁ and S ₂ made of, for example, sapphire are mounted in the recesses 2a and 3a of the susceptors 2 and 3, and the susceptors 2 and 3 are horizontally arranged around their central axes. Rotate.

While energizing the coil 6 to heat the substrates S ₁ and S ₂ to a predetermined temperature, trimethylgallium (TMG) gas + ammonia (NH) is supplied through the reaction gas supply pipe 4 and the nozzle 4a.
₃ ) A reaction gas G prepared by mixing gas + hydrogen (H ₂ ) gas is supplied into the reaction tube 1.

The reaction gas G is supplied from the nozzle 4a to the susceptor 2,
Blown between 3, they flow along opposite substrate S _1, S ₂ as a guide, in contact with the substrate S _1, S ₂ surface G
The aN crystal is grown to form a film.

The reaction gas may be supplied from individual nozzles for each type of gas. In this case, a plurality of nozzles are arranged in parallel so as to face the gaps between the susceptors 2 and 3 facing each other. As a result, the conditions such as the nozzle position and the jetting speed can be controlled independently, and a better film can be formed and the quality of the crystal film can be improved.

In the first embodiment described above, each susceptor 2,
Although the case where the substrates S ₁ and S ₂ are mounted facing each other has been shown, the substrates may be mounted on only one of them.

When the substrate is mounted on only one of the susceptors 2 or 3, it is desirable to mount it on the upper susceptor 2 in consideration of the effect of thermal convection on the reaction gas. When two substrates are installed, the nozzle 4a is positioned below the center of the gap between the susceptors 2 and 3 in consideration of the effect of thermal convection in order to make the growth layers on both substrates have the same film quality. It is desirable to position it closer.

Further, in this case, it is desirable that both the susceptors 2 and 3 rotate in the same direction so as to suppress the turbulence of the reaction gas flow. (Numerical example) Two substrates whose main surface is the c-plane of sapphire are mounted on the facing surfaces of the carbon susceptors which are arranged facing each other at an interval of 1 to 10 mm in the upper and lower directions, and the substrates are heated to 1150 ° C. While heating, NH ₃ as a reaction gas:
3.2 l / min, TMG: 24 μmol / min, H ₂ gas 1
l / min was passed between the carbon susceptors to form a film.

As a result, the two substrates (wafers) on which the GaN growth layer having substantially the same quality as the growth layer obtained by the two-flow MOCVD method are formed, have the reaction gas flow rates required in the conventional method. It was confirmed that the gas flow rate was about 40%. (Embodiment 2) FIG. 2B is a schematic view showing Embodiment 2 of the present invention. In this Embodiment 2, the reaction tube 1 shown in FIG. This corresponds to a state in which they are arranged so as to be substantially vertical.

In the second embodiment, the susceptors 2 and 3 are vertically arranged at predetermined intervals (1 to 10 mm) with the mounting surfaces of the substrates S ₁ and S ₂ facing each other. Each can be rotated in the vertical plane. A nozzle for supplying a reaction gas is installed at the lower end of the gap between the two susceptors 2 and 3 and at substantially the center of the gap.

In the second embodiment, since the reaction gas blown out from the nozzle receives the heat causing the heat convection from the susceptors 2 and 3 on both sides substantially equally, the deviation of the reaction gas flow is small. A uniform film can be formed on S ₁ and S ₂ .

The number of substrates may be one, and in this case, it may be attached to either side of the susceptors 2 and 3. The other structure is substantially the same as that of the first embodiment, and the description is omitted.

Of course, according to the present invention, a plurality of growth layers can be sequentially formed on the substrate.

[0037]

As described above, in the first aspect of the invention, the substrate is mounted on at least one of the facing surfaces of the pair of facing members, and the reaction gas is passed between the facing members to form a film. Therefore, the reaction gas is guided to the opposite surface and naturally flows along the substrate surface, so that no pressing gas is required, the reaction gas and the substrate are contacted without waste, and a homogeneous crystal growth film is obtained. As a result, the amount of reaction gas can be significantly reduced.

That is, in the first aspect of the present invention, the substrate is mounted on at least one of the opposing surfaces of the pair of opposing members, and the reaction gas is allowed to flow between them so that the opposing surface serves as a guide for the reaction gas. It is functional and requires no pressing gas as in the prior art, and allows the reaction gas to efficiently flow along the substrate surface.

In the second aspect of the present invention, the reaction gas is caused to flow from the lower side between the facing members facing each other in the vertical direction, so that the heat generated by the facing members having a high temperature exerts a heat convection on the reaction gas flow. That is, the adverse effect can be reduced, and a uniform film can be formed.

That is, in the second aspect of the invention, the influence of heat convection due to the heat of the facing member can be reduced by causing the reaction gas to flow vertically.

In the third aspect of the invention, the equipment can be simplified by supplying the reaction gas from one nozzle, and the reaction gas can be individually supplied from the plurality of nozzles. The blowing position and the like can be controlled, and uniform film formation can be performed on each substrate surface, and the quality of the crystal film can be improved.

That is, in the third aspect of the invention, the reaction gas is allowed to flow from one or a plurality of nozzles between the susceptor so that the reaction gas flow and the surface of the substrate are efficiently contacted. It becomes possible to flow through.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an embodiment of the method of the present invention.

2A is an enlarged schematic view of the susceptor shown in FIG. 1, and FIG. 2B is a schematic view showing another arrangement example of the susceptor.

FIG. 3 is a schematic diagram showing an implementation state of a conventional method.

[Explanation of symbols]

1 reaction tube 2,3 susceptor 4 reaction gas supply tube 4a nozzle 5 exhaust tube S ₁ , S ₂ substrate

Claims (3)

[Claims] 1. A method for growing a semiconductor crystal film on a substrate using a reaction gas while heating the substrate, comprising a pair of opposing members whose opposing surfaces are spaced apart from each other and opposed to each other. A method for growing a semiconductor crystal film, comprising mounting a substrate on at least one side and allowing a reaction gas to flow between the opposite surfaces. 2. The semiconductor crystal according to claim 1, wherein the extending direction of the gap between the facing surfaces is a vertical direction, and the reaction gas is allowed to flow between the facing surfaces from below. Membrane growth method. 3. The method for growing a semiconductor crystal film according to claim 1, wherein the reaction gas is blown from one or a plurality of nozzles between the opposing surfaces.