JPH06132227A - Vapor growth method - Google Patents

Abstract

PURPOSE:To perform a crystal growth with high intra-plane uniformity of a group III mixed crystal composition in the vapor growth of a III-V compound semiconductor crystal containing In and Ga. CONSTITUTION:A carbon susceptor 4 is heated by a high-frequency coil 6, a group V raw material and a group III raw material gas except for In are introduced into a reaction tube 3 from a first raw material introducing port 1 near the susceptor 4, and a TMI using an inert gas as a carrier is introduced independently of the other group III raw material gas into the reaction tube 3 from a second raw material introducing port 2 distant from the susceptor 4 to grow a thin film on a InP substrate 5, whereby the intra-plane uniformity of the group III mixed crystal composition on the substrate is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth method for III-V compound semiconductor crystals.

[0002]

2. Description of the Related Art In the metal-organic vapor phase epitaxy method (MOVPE method) used for manufacturing optical devices and high-speed devices, crystals having good characteristics can be grown over a large area, and active research has been promoted. Came.

In recent years, the analysis of carrier gas flow in a reaction tube has been advanced by simulation (Journal of Crystal Growth (Journal of Crystal Growth)).
fCrystal Growth), Volume 100, 5
(P. 45), good crystal characteristics are becoming obtainable not only under reduced pressure growth but also under normal pressure growth (Journal of Applied Physics (Journal)).
of Applied Physics, 67th
Vol. 12, p. 7578).

FIG. 3 shows a generally used reaction tube shape. Many of the raw materials used in the MOVPE method correspond to Lewis acids and Lewis bases, and intermediate products (adducts)
Easy to form. In particular, the formation of intermediate products becomes remarkable in atmospheric pressure growth. Therefore, as shown in FIG. 3, in order to reduce the contact between the group III raw material and the group V raw material, the first raw material introduction port 1 and the second raw material introduction port 2 are separately provided as the raw material introduction ports. The raw material introduction ports 1 and 2 are passed through the quartz reaction tube 3 to extend to the vicinity of the semiconductor crystal substrate 7 on the carbon susceptor, and the group V raw material is fed from the first raw material introduction port 1.
Group III raw materials are separately introduced from the second raw material introduction port 2 (Journal of Crystal Growth (Jou
rnal of Crystal Growth),
107, 192). In the figure, 6 is a high frequency coil.

[0005]

When growing a III-V group compound semiconductor crystal containing In and Ga using the horizontal reaction tube shown in FIG. 3, trimethylindium (TMI) and trimethylgallium (TMG) at the crystal growth temperature are used. )
Because the decomposition rates of the
The homogeneity of the group composition was reduced.

An object of the present invention is to solve this problem and to provide a vapor phase growth method for a III-V group compound semiconductor having excellent in-plane uniformity of doping.

[0007]

In order to achieve the above object, a vapor phase growth method according to the present invention comprises a substrate installed on a susceptor in a horizontal reaction tube and a plurality of raw material inlets having different diffusion distances to the susceptor. A group III source gas and a group V source gas containing trimethylindium (TMI) are introduced into the reaction tube from the above, and these are brought into contact with the substrate on the susceptor, and the group III-V compound semiconductor containing In and Ga is placed on the substrate. A vapor-phase growth method for growing a crystal, wherein trimethylindium (TMI) is introduced from a raw material inlet located at the farthest distance from the susceptor, and other group III source gas and group V source material other than trimethylindium (TMI) are introduced. Gas is introduced through another raw material inlet.

Further, in the vapor phase growth method according to the present invention, a substrate is placed on a susceptor in a horizontal reaction tube, and trimethylindium (TMI) is introduced into the reaction tube from a plurality of raw material inlets having different diffusion distances to the susceptor. A Group III source gas containing V and a Group V source gas containing V are introduced, and these are brought into contact with the substrate on the susceptor to contain In and Ga on the substrate II
A vapor phase epitaxy method for growing a group IV compound semiconductor crystal, wherein trimethylindium (TMI) is introduced from a raw material inlet located farthest from a susceptor using an inert carrier gas to produce trimethylindium (TMI).
The group III source gas and the group V source gas other than I) are
It is introduced from another raw material inlet.

[0009]

When the crystal growth is performed by introducing trimethylindium (TMI) and trimethylgallium (TMG), which are group III source gases, through the second source inlet 2 using the horizontal reaction tube shown in FIG. In the group III composition of the above, In is excessive on the upstream side and Ga is excessive on the downstream side. It is considered that this is because the TMI used at the crystal growth temperature has a higher decomposition rate than TMG and thus decomposes faster, and the source gas is exhausted on the downstream side and the concentration decreases.

Further, when triethylgallium (TEG) is used as a raw material for gallium, the decomposition rate of the raw material is slower than that of TMG, so that the uniformity of the group III composition is further deteriorated. When triethylindium (TEI) is used as the indium raw material, the intermediate reaction with the group V raw material becomes active, and the In concentration is lowered due to the adduct formation reaction, and the group III composition is more uniform. descend.

Therefore, in the present invention, as a method for reducing the supply of TMI to the upstream portion of the substrate, only TMI is introduced from the second raw material introduction port located farthest from the susceptor, and the other group III except TMI is introduced. By utilizing the fact that the diffusion distance of TMI is longer than that of the raw material, the group III mixed crystal composition in the substrate surface is made uniform.

Further, in the present invention, as a method of slowing down the decomposition rate of TMI raw material, the carrier gas of TMI is an inert gas. It is generally known that the decomposition mechanism of an organic metal having a methyl group is hydrogenolysis in a hydrogen carrier gas and thermal decomposition in an inert gas (Journal of Electrochemical Society (Journal). of Electrochemical
al Society), Vol. 132, p. 677).
Furthermore, it is known that pyrolysis has a slower decomposition rate than hydrocracking. Therefore, in the present invention, the carrier gas of TMI is an inert gas, and the TMI is TM of hydrogen carrier gas.
It is not mixed with G, but is introduced independently from the second raw material introduction port located at the farthest distance from the susceptor, and the decomposition rate of TMI is reduced to homogenize the group III mixed crystal composition in the plane of the substrate. To do.

[0013]

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

(Embodiment 1) FIG. 1 is a block diagram showing an apparatus using a vapor phase growth method according to Embodiment 1 of the present invention.

In FIG. 1, a carbon susceptor 4 is provided on the central wall of a quartz reaction tube 3 and has a size of 2 inches I
The nP substrate 5 is supported by the carbon susceptor 4 and installed in the reaction tube 3. 6 is a high frequency coil.

The raw material introduction port is divided into two parts, the upper and lower parts, and the first raw material introduction port 1 and the second raw material introduction port 2 are arranged in this order from the side closer to the carbon susceptor 4.

An InGaAa layer lattice-matched to the InP substrate is grown using trimethylindium (TMI), trimethylgallium (TMG), and arsine (AsH ₃ ) as raw materials.

In the first embodiment, the carbon susceptor 4 is heated by the high frequency coil 6. Then, TMI is made independent from other group III source gas and group V source gas,
I was introduced into the reaction tube 3 from the second raw material introduction port 2 which is the farthest distance from the susceptor 4 using hydrogen carrier gas. On the other hand, the group III source gases other than TMI and the group V source gases (TMG, AsH ₃ ) were introduced into the reaction tube 3 through the first source inlet 1 using a hydrogen carrier gas.

The pressure in the reaction tube 3 is 760 Torr, the carrier gas flow rate is 10 SLM, and the In
When the GaAs layer was grown, the lattice irregularity due to X-ray diffraction in the plane of the 2-inch InP substrate was within 1 × 10 ⁻³ ,
The in-plane uniformity of the group III composition was good.

(Embodiment 2) FIG. 2 is a constitutional view showing an apparatus used in a vapor phase growth method according to Embodiment 2 of the present invention. The apparatus of this embodiment has the same configuration as that of the first embodiment.

In the present embodiment, the group III source gas other than TMI and the group V source gas were introduced into the reaction tube 3 from the first source inlet 1 using hydrogen carrier gas.

The TMI is made independent of the other group III source gas and the group V source gas (TMG, AsH ₃ ), and the TMI uses the nitrogen carrier gas and the second source material introduction port 2 which is the farthest distance from the susceptor 4. It was introduced into the reaction tube 3.

The pressure of the reaction tube 3 is 760 Torr, the carrier gas flow rate is 10 SLM, and the In
When the GaAs layer was grown, the lattice mismatch due to X-ray diffraction in the plane of the 2-inch InP substrate was within 5 × 10 ^−4.
The in-plane uniformity of the group II composition was extremely good.

On the other hand, TMI is changed to T by hydrogen carrier gas.
When introduced through the second raw material inlet 2 together with MG,
The lattice mismatch due to X-ray diffraction in the plane of the 2-inch InP substrate is
It was about 10 ⁻³ .

[0025]

As described above, by using the present invention,
Using a horizontal reaction tube having a plurality of raw material inlets, In and G
In a vapor phase growth method of growing a III-V group compound semiconductor crystal containing a on a substrate, by introducing trimethylindium (TMI) from a raw material introduction port farthest from a susceptor, independently of other III group raw materials. , I
Crystal growth with high in-plane uniformity of the II group composition can be performed.

By further introducing trimethylindium (TMI) using an inert carrier gas, II
Crystal growth with high in-plane uniformity of group I composition can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an apparatus used in a vapor phase growth method according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing an apparatus used for a vapor phase growth method according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing an apparatus used in a conventional vapor phase growth method.

[Explanation of symbols]

 1 1st raw material inlet 2 2nd raw material inlet 3 Quartz reaction tube 4 Carbon susceptor 5 InP substrate 6 High frequency coil 7 Semiconductor crystal substrate

Claims (2)

[Claims] 1. A substrate is placed on a susceptor in a horizontal reaction tube, and trimethylindium (TMI) is introduced into the reaction tube from a plurality of raw material inlets having different diffusion distances to the susceptor.
A group III source gas and a group V source gas containing hydrogen are introduced, and these are brought into contact with the substrate on the susceptor to bring In
A vapor phase growth method for growing a III-V compound semiconductor crystal containing Ga and Ga, wherein trimethylindium (TMI) is introduced from a raw material inlet located farthest from the susceptor, and trimethylindium (TMI) is removed. Another group III source gas and group V source gas are introduced from another source inlet, which is a vapor phase growth method. 2. A substrate is placed on a susceptor in a horizontal reaction tube, and trimethylindium (TMI) is introduced into the reaction tube from a plurality of raw material inlets having different diffusion distances to the susceptor.
A group III source gas and a group V source gas containing hydrogen are introduced, and these are brought into contact with the substrate on the susceptor to bring In
A vapor phase growth method for growing a III-V group compound semiconductor crystal containing Ga and Ga, wherein trimethylindium (TMI) is introduced from a raw material introduction port farthest from the susceptor using an inert carrier gas, A vapor phase growth method, characterized in that the other group III source gas and the group V source gas other than trimethylindium (TMI) are introduced from another source inlet.