JPH0547668A - Crystal growth method for compound semiconductor - Google Patents

Abstract

PURPOSE:To grow an upper layer compound semiconductor crystal of high quality when different type compound semiconductors are grown at the same temperature and to form an abrupt hetero boundary by simultaneously supplying carrier gas and gas having heavier specific weight than that of the carrier gas when a material of an element for constituting a compound semiconductor crystal is supplied. CONSTITUTION:When an InAs crystal is grown on a substrate 3, (CH3)3In and AsH3 are used as materials. The (CH3)3In and AsH3 are switched by a valve (b), alternately supplied to a reaction tube 1, and grown. H2 is used as the carrier gas, and Ar is simultaneously supplied at the time of supplying the (CH3)3In. Thus, since a surface temperature of the substrate 3 can be effectively lowered, the (CH3)3In can be supplied to the surface of the substrate in an undecomposed state as it is, and the methyl indium reaching the substrate 3 is eliminated as it is or rapidly decomposed to become In so as to contribute to the growth. Accordingly, an InAs atomic layer epitaxial growth can be conducted at 400 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor crystal growth method, and more particularly, to a compound semiconductor crystal growth method for growing a compound semiconductor crystal by using atomic layer epitaxial growth that enables crystal growth in atomic layer units. Regarding the improvement of the method. In recent years, for the purpose of developing electronic devices with new functions by improving the performance of electronic devices by improving their performance and further achieving excellent physical properties not found in conventional bulk materials, compound semiconductor crystal There is a strong demand for a compound semiconductor crystal growth method capable of controlling the impurity concentration in atomic layer units.

[0002]

2. Description of the Related Art Conventionally, in an atomic layer epitaxial growth method using an organic metal, for example, when growing a high quality InAs crystal, trimethylindium [(CH ₃ ) ₃ In, TMI] is used as an In raw material and As material is used as an As raw material. arsine (AsH _3), the growth temperature (substrate temperature)
The temperature was set to 350 ° C., and each source gas was alternately supplied onto the substrate crystal to grow the monoatomic layer. When growing a good quality GaAs crystal, trimethylgallium [(CH ₃ ) ₃ Ga, TMG] is used as a Ga raw material, AsH ₃ is used as an As raw material, the growth temperature is set to 500 ° C., and each raw material gas is alternately changed. Then, it was supplied onto the substrate crystal to grow the monoatomic layer. In addition, H ₂ was used as a carrier gas for both InAs crystal and GaAs crystal growth.

[0003]

However, in the above-described conventional compound semiconductor crystal growth method, when growing a compound semiconductor crystal (InAs / GaAs) having a hetero interface, as shown in FIG. 4, InAs and GaAs are grown. Since there is no place where the growth temperatures are different from each other, when the growth temperature is set to 350 ° C in accordance with InAs, GaA
The growth of s does not occur, and since the temperature is high when the growth temperature is set to 500 ° C. in accordance with GaAs, mutual diffusion of constituent atoms occurs near the hetero interface, making it difficult to form a steep hetero interface. There was a problem.

On the other hand, InAs / InAs and GaAs / G
In the case of homoepitaxial growth in which homogenous compound semiconductors such as aAs are grown, the above-mentioned problems such as the growth of the upper compound semiconductor crystal and the difficulty of forming a steep hetero interface do not occur.
The above problem arises in the case of heteroepitaxial growth in which heterogeneous compound semiconductors such as P / GaP and InAs / GaAs are grown.

Therefore, the present invention is based on InP / GaP and InA.
When growing heterogeneous compound semiconductors such as s / GaAs at approximately the same temperature without changing the growth temperature, good quality GaP or Ga
An object of the present invention is to provide a compound semiconductor crystal growth method capable of growing an upper layer compound semiconductor crystal such as As, and making it difficult to cause mutual diffusion of constituent atoms at the hetero interface to form a steep hetero interface. There is.

[0006]

In order to achieve the above object, the method for growing a compound semiconductor crystal according to the present invention simultaneously supplies a gas having a specific gravity higher than that of a carrier gas to be supplied when a raw material of an element constituting the compound semiconductor crystal is supplied. In addition to the supply, the raw material and the other raw material constituting the compound semiconductor crystal are alternately supplied into the growth chamber to grow the compound semiconductor crystal.

In the present invention, the raw material of the element constituting the compound semiconductor crystal may be a raw material having a lower decomposition temperature than other raw materials constituting the compound semiconductor crystal. Is trimethylindium. Examples of the combination mode of the carrier gas according to the present invention and the gas having a higher specific gravity than the carrier gas include H ₂ / Ar, H ₂ / N ₂ , H ₂ / Ne, and H ₂ /
Kr, H ₂ / Xe, H ₂ / Rn, Ar / Ne, Ar / K
r, Ar / Xe, Ar / Rn, N ₂ / Ne, N ₂ / K
r, N ₂ / Xe, N ₂ / Rn and the like can be mentioned.

[0008]

In the present invention, for example, an InAs crystal is used as a conventional MO
In the case of growing using a CVD method apparatus, TMI and AsH ₃ are used as raw materials as described later as an example,
This TMI and AsH ₃ are alternately supplied to grow. H ₂ is used as the carrier gas, but argon (Ar) is used as the carrier gas when supplying TMI.

In the past, when atomic layer epitaxial growth of InAs was carried out at a substrate surface temperature (growth temperature) of 400 ° C. or higher, TMI was decomposed in the vapor phase because of the high growth temperature, and InAs was deposited on the substrate surface. It was supplied in the form of atoms. Then, In is bonded to each other on the surface of the substrate, and it is not possible to obtain the self-limiting effect in which the growth automatically stops at one atomic layer.

On the other hand, in the present invention, the carrier gas to be supplied, for example, H ₂ (molecular weight 2), which has a higher specific gravity, for example, A
Since the substrate surface temperature can be effectively lowered by using r (molecular weight 40), TMI can be supplied to the substrate surface without decomposition. Therefore, the methylindium that reaches the substrate can be desorbed as it is, or can be quickly decomposed into In, which can contribute to the growth. Therefore, since it is possible to prevent methyl indium from being adsorbed on In, atomic layer epitaxial growth of InAs having a self-limiting effect can be performed at 400 ° C. or higher.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a vapor phase growth apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a quartz reaction tube, and in this quartz reaction tube 1, a substrate 3 mounted on a carbon susceptor 2 is arranged. 4 is connected to the carbon susceptor 2 and is arranged above the quartz reaction tube 1.
Reference numeral 5 is a pressure controller for appropriately evacuating the inside of the quartz reaction tube 1. Reference numeral 5 denotes a quartz reaction tube 1 arranged around the quartz reaction tube 1.
An RF coil that heats the inside. 6 is TMI gas, TM
It is a gas switching valve for appropriately switching and introducing G gas, AsH ₃ gas and H ₂ gas into the quartz reaction tube 1, and this gas switching valve 6 is further connected to a pressure controller 7 for vacuum evacuation. The temperature of the substrate 3 is measured by a thermocouple passing through the carbon susceptor 2 and the like.

In this embodiment, the atomic layer epitaxial growth of the (InAs) ₁ (GaAs) ₁ superlattice on the InP (100) substrate is conventionally used for the MO-CVD method, and the vapor phase growth apparatus shown in FIG. 1 is used. Was carried out as described below, and the results were obtained as shown in FIG. In this embodiment, the growth apparatus shown in FIG. 1 is used, and the growth pressure is, for example, 20 To.
The growth was performed at rr and the growth temperature at 500 ° C. TMI
The bubbler temperatures of TMG and TMG were 5.5 ° C. and 3.0 ° C., respectively, and Ar and H ₂ carriers were aerated to supply the respective raw materials. Then, as shown in FIG. 3, the TMI supply time X is shown in FIG.
Is set as shown on the abscissa of FIG.
Growth thickness per cycle (InAs) ₁ (GaAs)
_{1 The} ratio to the thickness of one monolayer was determined.

In this embodiment, as shown in FIG.
When the supply time of I reaches about 3 seconds, the growth thickness does not increase even if the supply time X is further increased, and the atomic layer epitaxial growth in which the growth thickness per cycle is kept at one molecular layer is achieved. The effect is that it can be done. Therefore, even at a growth temperature of 500 ° C., atomic layer epitaxial growth can be performed without decomposing TMI in the vapor phase, and the growth temperature region of atomic layer epitaxial growth of a compound semiconductor containing In can be expanded. Therefore, it can greatly contribute to the development of an electronic device material having a hetero interface composed of a compound semiconductor having greatly different physical properties.

In the above embodiment, the case where Ar is used as the chemically inert carrier gas having a higher specific gravity than H ₂ has been described, but the present invention is not limited to this, and N ₂ and Ne are used. , Kr, Xe, Rn, etc. may be used.

[0015]

According to the present invention, InP / GaP and In
When heterogeneous compound semiconductors including 3-5 group and 2-6 group such as As / GaAs are grown at approximately the same temperature without changing the growth temperature, a good quality upper layer compound semiconductor crystal such as GaP or GaAs is grown. In addition, it is possible to prevent the mutual diffusion of the constituent atoms at the hetero interface and form a steep hetero interface.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a result of a growth thickness per one cycle according to an embodiment of the present invention.

FIG. 3 is a diagram showing growth conditions according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a problem of a conventional example.

[Explanation of symbols]

 1 quartz reaction tube 2 carbon susceptor 3 substrate 4 pressure controller 5 RF coil 6 gas switching valve 7 pressure controller

Claims (3)

[Claims] 1. A gas having a specific gravity higher than that of a carrier gas supplied when supplying a raw material of an element constituting a compound semiconductor crystal is simultaneously supplied into the growth chamber, and the raw material and another raw material constituting the compound semiconductor crystal. And (3) are alternately supplied into the growth chamber to grow a compound semiconductor crystal. 2. The method for growing a compound semiconductor crystal according to claim 1, wherein the raw material of the element constituting the compound semiconductor crystal is a raw material having a lower decomposition temperature than other raw materials constituting the compound semiconductor crystal. 3. A step of growing, on the compound semiconductor crystal, a second compound semiconductor crystal having a decomposition temperature of constituent elements higher than that of the compound semiconductor crystal, and the compound semiconductor crystal of the opposite side is grown at the high decomposition temperature. The method for growing a compound semiconductor crystal according to claim 1, wherein the compound semiconductor crystal is grown.