JPH0657635B2 - Vapor phase growth equipment - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a vapor phase growth apparatus for growing a III-V compound semiconductor thin film crystal using an organometallic compound as a raw material.

(Prior art and its problems) GaAs using trimethylgallium (TMG) as an organic metal compound and arsine gas as a hydride of Group V
A conventional technique for growing a crystal will be described.

Conventionally, as shown in FIG. 1, a TMG gas inlet 1 and an arsine gas inlet 2 are provided, and a conductive susceptor 4 such as carbon is fixedly arranged in a reaction tube 6, and the susceptor 4 is
The structure is such that the substrate 3 is arranged on the top. In order to grow the crystal, a high frequency is applied to the high frequency heating coil 5 and the susceptor 4 is heated to 750 ° C. by the induction heating method. next,
When TMG and arsine gas are introduced into the reaction tube 6, each gas decomposes in the vicinity of the heated substrate 3 and becomes GaAs and grows on the substrate 3. In this growth,
In order to obtain a high quality compound semiconductor crystal, the cleanliness of the surface of the substrate 3 is important. Particularly in the case of so-called heteroepitaxial growth in which a compound semiconductor crystal is grown on silicon, the inside of the reaction tube 6 is set to a hydrogen atmosphere to keep the silicon substrate at a high temperature of about 1000 ° C. to remove dirt and a natural oxide film on the surface of the substrate 3. A cleaning process to do so is essential. However, in the conventional apparatus, the decomposition products of GaAs crystals and TMG deposited on the tube wall of the reaction tube 6 downstream of the substrate 3 during the previous growth are higher than the GaAs growth temperature due to the high temperature of 1000 ° C. during the cleaning treatment, There is a problem that the reaction tube 6 evaporates from the tube wall and adheres to the substrate 3, so that the cleaning process contaminates the substrate. Due to the contamination, a so-called anti-phase domain in which GaAs (100) and GaAs (00) are mixed is generated when a Si (100) substrate is used.

Further, conventionally, in order to remove the product adhering to the tube wall of the reaction tube 6, a method of flowing HCl and cleaning it by etching has been adopted. In the case of homoepitaxial growth in which a GaAs crystal is grown on a GaAs substrate, the above-mentioned cleaning with HCl (cleaning treatment) is effective. However, when silicon is used as the substrate 3, the reaction tube 6 is not removed even after cleaning.
The trace amount of HCl retained inside corrodes the SiO ₂ used in the reaction tube 6, and the oxygen component of this SiO ₂ changes to the silicon substrate 3
However, there is a drawback that the compound semiconductor crystal does not grow because the surface of the compound is oxidized.

(Object of the Invention) It is an object of the present invention to provide a vapor phase growth apparatus capable of keeping a clean surface of a silicon substrate and growing a compound semiconductor on the silicon substrate by using an organic metal raw material for crystal growth. .

(Characteristics of the Invention) The present invention is provided with a cleaning treatment space in which a hydride gas of a group V element flows and a substrate can be temporarily stored in a reaction tube, and a cleaning treatment of a substrate is performed in the cleaning treatment space. It is configured such that the substrate can be moved to a position where the hydride gas of the group V element and the organometallic compound gas of the group III element flowing out from the cleaning processing space merge to perform vapor phase growth. Is the most important feature. In the conventional technique, the substrate is fixed in the reaction tube, and III is attached to the substrate.
It is configured to send a mixed gas of an organometallic compound gas of a group element and a hydride gas of a group V element. The above points differ from the prior art.

(Example) Hereinafter, the Example of this invention is described in detail.

FIG. 2 is a block diagram of a vapor phase growth apparatus according to the present invention. In this example, trimethylgallium and arsine are used to make Ga
An example of growing an As crystal on a Si substrate will be described, but the present invention is not limited to the above combination, and a compound semiconductor such as GaP or InP is grown using trimethylgallium, trimethylindium, phosphine, or the like. It can also be applied in cases.

In FIG. 2, 11 is a trimethylgallium gas inlet,
12 is an arsine gas inlet, 13 is a silicon substrate, 14 is a carbon susceptor, 15 is a high-frequency heating coil, 16 is a cleaning processing space in which arsine flows and the substrate can be temporarily stored, 17 is an exhaust port, and 18 is a substrate. A rod for moving, 19 is a squeeze, 20 is a reaction tube, 21 is a flow of trimethylgallium gas, and 22 is a flow of arsine gas. The trimethylgallium gas inlet 11 is an HC for cleaning the inside of the reaction tube 20.
l Also serves as a gas inlet. It is important that the inlet for the HCl gas does not have the same flow path as the arsine gas, and another inlet may be installed. The reaction tubes 20 are all made of quartz glass. Fig. 3 shows the cleaning processing space 16 for the temporary storage of substrates.
The case where the substrate 13 is housed is shown. In such an arrangement of the substrate 13, gas components other than arsine outside the cleaning processing space 16 for temporarily housing the substrate are swept away by the flow 22 of arsine gas and do not enter the cleaning processing space.

In order to grow GaAs on the Si substrate 13 using the above apparatus, it is carried out as follows. After cleaning the Si substrate 13, the natural oxide film formed on the surface is removed with an HF aqueous solution and immediately put into the reaction tube 20. Move the susceptor 14 on which the substrate 13 is placed to the position shown in FIG.
Introduce H ₂ gas from 11 and 12. A high frequency power is applied to the high frequency heating coil 15 to heat the substrate 13 to 1000 ° C. to perform a cleaning process for removing a natural oxide film and dirt on the surface of the substrate 13. Next, the temperature of the substrate 13 is lowered to 400 ° C., and arsine gas is introduced through the inlet 12 and flowed as indicated by 22. next,
Introduce trimethylgallium gas from the inlet 11 and
After 21 becomes steady, the rod 18 is moved to draw the substrate out of the cleaning processing space 16, and the substrate 13 is placed in the confluence region where the trimethylgallium gas flow 21 and the arsine gas flow 22 merge as shown in FIG. Start growing as arranged. After 2 minutes, the substrate 13 is placed again in the arrangement state shown in FIG. 3 to stop the growth. Through such growth process, Si substrate
A 200 Å thick GaAs film was grown on 13. Next, 750 ℃
Then, the temperature of the substrate 13 was raised and the arrangement of FIG. With such a process, the film thickness on the Si substrate 13 is 2.
At 5 μm, a mirror-like GaAs film that inherited the orientation of the substrate 13 was grown. When the crystallinity of the grown film was examined by an X-ray two-crystal diffraction method, it was a single crystal having no anti-phase domain equivalent to the half-value width of the diffraction line of the bulk GaAs crystal.

After the above growth process, GaAs polycrystal has grown on the susceptor 14. In order to remove this, the susceptor 14 was kept in the arrangement shown in FIG. 2, HCl gas was introduced from the inlet 11, and the susceptor 14 was heated to 1000 ° C. to remove the GaAs polycrystal. Then, stop the HCl gas, flow H ₂ gas, and press the susceptor 1
The HCl gas component soaked in 4 was volatilized. During this cleaning process, H ₂ gas was constantly flown through the inlet 12 so that the cleaning component 16 did not contain HCl components. The process of growing the GaAs crystal on the Si substrate 13 described in the above example was repeated again, but the same good growth as in the first time was successful, and reproducibility was confirmed. This is a reaction tube
This is because the 20 and the susceptor 14 are well cleaned and there is no residual HCl or GaAs, and the Si substrate 13 is kept clean.

4 (a) and 4 (b) are a longitudinal sectional view and a lateral sectional view showing a second embodiment of the present invention. The apparatus of this embodiment is of a vertical type, and the substrate 33 is placed on a disc-shaped susceptor 34, and the substrate 33 is moved by rotating the susceptor 34 as described in the first embodiment. For growth, the substrate 33 is placed on the susceptor 34 as in the first embodiment, and the substrate 33 is placed in the cleaning treatment space 36 immediately below the arsine gas inlet 32 by operating the susceptor rotating shaft 38. 39 is a squeeze. First, the H ₂ gas was introduced from the arsine gas inlet 32, and the substrate 33 was introduced by the high frequency heating coil.
Is heated to perform a cleaning process for removing the natural oxide film on the surface of the substrate 33. Next, the flow of arsine gas 42
And trimethylgallium gas flow 41 are introduced through respective inlets 32 and 31, the susceptor 34 is rotated, and a fourth region is formed in the confluence region where arsine gas and trimethylgallium gas merge.
The substrate 33 is positioned and grown as shown by the dotted lines in FIGS.

In Examples 1 and 2, the high frequency induction heating method was used for heating, but an infrared lamp may be used. In addition, it goes without saying that in the first and second embodiments, H ₂ gas may be mixed with each of arsine gas and trimethylgallium gas and used as a carrier gas. Further, although one substrate is shown in FIG. 4, a plurality of substrates may be placed.

(Effect of the Invention) As described above, the vapor phase growth apparatus according to the present invention is provided with the cleaning treatment space in which the hydride gas of the group V element flows in the reaction tube and the substrate can be temporarily stored. At the gas outlet of the above, a merging region where the hydride gas of the group V element and the group III organometallic compound gas merge is obtained, and the substrate can move to the cleaning space and the merging region. Because of the structure with the above mechanism, HCl is used for cleaning the susceptor and reaction tube.
Even if it is used, the substrate remains in the cleaning process space until it remains just before growth.
Can be kept in a HCl-free atmosphere. Therefore, since the surface of the substrate can be kept clean during the growth, it is possible to grow a compound semiconductor having no antiphase domain with good reproducibility. Further, after using HCl, there is no need to perform a long-term purging for expelling residual HCl from the reaction tube, so that there is an effect that the use efficiency of the apparatus is improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the concept of a conventional vapor phase growth apparatus, FIG. 2 is a schematic vertical sectional view showing a first embodiment of the apparatus of the present invention, and FIG. 3 is a view for explaining the operation of the apparatus of the present invention. Vertical section schematic,
4 (a) and 4 (b) are a longitudinal sectional view and a transverse sectional view taken along the line IV-IV showing the second embodiment of the present invention. 1 ... Trimethylgallium gas inlet, 2 ... Arsine gas inlet, 3 ... Substrate, 4 ... Susceptor, 5 ... High frequency heating coil, 11 ... Trimethylgallium gas inlet, 12 ... Arsine gas inlet, 13 ... Substrate, 14 ... Susceptor, 15 ... High frequency heating coil, 16 ... Cleaning space, 17 ... Exhaust port, 18 ... Rod for moving substrate, 19 ... Squeezing, 20 ... Reaction Tube, 21 ... Trimethylgallium gas flow,
22 …… Arsine gas flow, 31 …… Trimethylgallium gas inlet, 32 …… Arsine gas inlet, 33 …… Substrate, 34 …… Susceptor, 35 …… High frequency heating coil, 36 …… Cleaning space, 37 ...... Exhaust port, 38 ...... Susceptor rotating shaft, 39 ...... Squeezing, 41 ...... Trimethylgallium gas flow, 42 ...... Arsine gas flow.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-53-20763 (JP, A) JP-A-60-25227 (JP, A) JP-A-62-145725 (JP, A)

Claims (3)

[Claims] 1. A group III element containing an organometallic compound gas and V
By supplying a hydride gas of a group V element in a vapor phase growth apparatus for transporting the group element with a hydride gas into the reaction tube and growing a III-V group compound semiconductor crystal on the substrate accommodated in the reaction tube, The reaction tube is provided with a cleaning processing space formed so that the organometallic compound gas does not flow thereinto and capable of temporarily storing the substrate.
At the gas outlet of the cleaning processing space, a merging region where the hydride gas and the organometallic compound gas merge is formed, and the substrate moves to the cleaning processing space and the merging region. A vapor phase growth apparatus having a mechanism capable of performing the above. 2. The cleaning treatment space comprises a small chamber connected to the hydride gas inlet and having a squeezed opening for introducing a flow of the hydride gas into the reaction tube.
2. The substrate according to claim 1, wherein the substrate is formed so as to be able to move between the cleaning processing space and the confluence region in the reaction tube through the aperture. Vapor growth equipment. 3. The cleaning processing space is squeezed between an upper tube wall of the vertical reaction tube and a susceptor for holding a substrate arranged in the reaction tube at an appropriate distance from the upper tube wall. Is formed by being separated from the reaction tube by a mechanism, an inlet for the hydride gas is provided in the upper tube wall in the cleaning processing space, and the substrate on the susceptor is cleaned by the rotating mechanism of the susceptor. Formed so as to be mutually movable between the merging region formed in the vicinity of the introduction port of the organometallic compound gas provided on the upper wall of the reaction tube outside the chemical treatment space and the cleaning space. The vapor phase growth apparatus according to claim 1, wherein