JPS60220926A - Vertical vapor growth device - Google Patents

Abstract

PURPOSE:To eliminate positioned deviation to generate in each replacement of sample and to obtain a grown layer with a uniform film thickness by a method wherein a tapered recess part has been prepared bored in the back surface of a susceptor for high-frequency heating, which is housed in the interior of the reaction furnace in such a way as to be able to detach freely, and a tapered protrusion part of the supporting stand is made to fit in the tapered recess part. CONSTITUTION:An RG coil 16 wound around on the outer periphery of a vertical vapor phase reacion furnace 1 provided with a gas lead-in duct 11 on its upper part and a gas lead-out duct 10 outside of its lower part, and a diffusion plate 12, which is located under the lower direction of the duct 11 and is used for making gas disperse homogeneously, and a sample stand 3, on which a sample 2 is placed, are housed in the interior of the furnace 1. A supporting rod made to penetrate the base of the furnace 1 is made to revolve by a rotating unit 9 provided outside of the furnace 1, the point of the rotating unit 9 is made to abut on the base of the sample stand 3 and the sample stand 3 is made to revolve in a prescribed number of revolutions. In this constitution, a tapered recess part 5 has been prepared bored in the central part of the back surface of the sample stand 3. A supporting stand 6 provided with a tapered protrusion part 7 is made to fit in this recess part 5 and the rotating shaft of the rotating unit 9 is fitted in a cylindrical frame 8 protruding in the lower direction from the supporting stand 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a vapor phase growth apparatus for growing a compound semiconductor thin film.

[Prior art and its problems]

Semiconductor lasers, such as gallium aluminum arsenide (Ga
ALAs) As a method for manufacturing semiconductor lasers, trimethyl gallium (TMG), which is a type of organic metal, is used.

Metal Organ pyrolysis vapor phase epitaxy (Metal Organ) is a method that utilizes the thermal decomposition of trimethylaluminum (TMA) and arsine (AsHs), a hydrogen compound of arsenic.
cChemical Vapor Depositio
n: MOCVD method) is known. When implementing the MOCVD method.

From the viewpoint of saving raw material gas, vertical vapor phase growth apparatuses are often used. In other words, in a vertical vapor phase growth furnace, the raw material gas is supplied almost perpendicularly to the upper surface of the crystal substrate, which is the raw material, so the direction of gas supply and the direction of vapor phase growth coincide, and therefore the gas growth can be achieved with a small supply of gas. Phase growth can be performed.

In the vapor phase growth method using thermal decomposition of organic metals, each sample is made of carbon or the like because it serves as a heat source during high-frequency heating. In general, these sample stands are mounted on a support stand made of quartz or the like and are removable to facilitate sample exchange.

This support stand has seven racks for stably supporting the sample stand.
On the other hand, a recess is provided at the bottom of the sample stage to fit into the recess to prevent the sample stage from shifting due to vibrations or the like. However, since the support stand is made of quartz glass, its dimensional accuracy is low, and the recess at the bottom of the sample stand is formed with a clearance of approximately 2W in diameter from the support stand flange. Therefore, each time the sample is replaced, the position of the sample stage changes with respect to the reaction tube. This problem is particularly problematic in systems containing At. That is, in a system containing ht, since At is extremely easily oxidized, it is important to prevent oxygen and moisture from entering the growth system in order to obtain high quality crystals. Furthermore, in order to prevent oxygen and moisture from entering the growth system, it is necessary to prevent oxygen and moisture from being adsorbed inside the reactor. For this reason, when loading and unloading wafers into the reactor, a specially devised front chamber is installed to prevent the inside of the reactor from being exposed to the outside air in order to prevent oxygen and moisture from adsorbing on the reactor inner walls, sample stand, etc. This is how it is done. In such a reaction system, the sample stage is placed in the reactor not directly, but through a machine.

It becomes particularly difficult to place the objects accurately each time on a table made of quartz or the like. For this reason, the annular gap formed between the inner wall of the reaction tube and the sample stage differs around the circumference of the sample stage, and as a result, the flow rate of the raw material gas differs in the circumferential direction each time.

As described above, depending on the force field table and the position where the sample was placed, the film thickness distribution within the wafer surface deteriorated, resulting in poor crystal growth reproducibility and low yield.

[Purpose of the invention]

The purpose of the present invention is to ensure that the sample stage on which the sample is placed is placed with good reproducibility without causing any positional shift each time the sample is replaced, thereby achieving growth with a uniform thickness and stable composition of the crystal growth layer. An object of the present invention is to provide a vapor phase growth apparatus capable of forming a layer.

[Summary of the invention]

The gist of the present invention is that four tapered parts are provided at the bottom of the sample support in the reactor, and the receiving part of the support that supports the sample has the same taper-like convexity as the taper provided at the bottom of the sample support. The reason is that the position of the sample stage can be effectively changed each time the sample is replaced.

〔Effect of the invention〕

According to the present invention, since the sample stage and the support stage fit together through a part of the taper, there is no mechanical positional shift, and a crystal growth substrate having a desired thickness and composition can be efficiently grown during crystal growth. can get. Therefore, when a semiconductor laser, for example, is manufactured using a substrate subjected to crystal growth according to the present invention, the oscillation wavelength can be stabilized.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing a vertical vapor phase growth apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an Aqf type vapor phase growth furnace, and within this growth furnace 1 a sample stage 3 on which a sample 2 is placed is arranged. A tapered recess 5 is formed in the sample table bottom 4, and a support 6VC that supports this is formed with a tapered convex part 7 having the same taper as the tapered recess 5 formed in the sample table bottom 4. has been done.

The sample support stand 3 is rotated by a rotation mechanism 9 via a shaft. A gas outlet duct 10 is connected to the lower part of the growth furnace 1, and a gas introduction duct 11 is connected to the upper part of the reactor 1. The raw material gas introduced from the gas introduction duct 11 is dispersed by the diffusion plate 12, mixed homogeneously, and then thermally decomposed in the reactor 1 to grow crystals on the substrate 2.
The waste gas is discharged from the exhaust gas treatment unit 14 through the three-way valve 13 and is treated therein. Further, a vacuum pump 15 is connected to the three-way valve 13 to provide a mechanism for discharging the gas inside the reactor 1.

On the other hand, a source gas source (not shown) and a flow rate control valve (not shown) are attached to the gas introduction duct 11. In this example, arsine (AsH3) gas diluted with hydrogen as a gas source, hydrogenated selenium (H2Se) gas diluted with hydrogen as a doping gas, and a hydrogen gas supply source are connected. Trimethylgallium (TMG) and trimethylaluminum (TMA), which are vaporized and supplied, are connected to jettilizing (DBZ), which serves as a doping gas. The arsine, trimethylgallium, and trimethylaluminum are thermally decomposed in the reactor to facilitate the vapor phase growth of gallium aluminum arsenide, and the hydrogen gas serves as a carrier gas. Reference number 16 in FIG. 1 is coils E and F for heating the sample to the growth temperature via the sample stage 3.

Next, a case will be described in which a gallium aluminum arsenide thin film growth layer is formed using a vapor phase growth apparatus having the above configuration.

First, the plane orientation (1
After cleaning the GaAs substrate 2 of 00) with an organic solvent, it is chemically etched with a sulfuric acid-based etching solution. Next, after drying the substrate, it is placed on the sample support stand 3 shown in FIG. 2. Next, the inside of the reactor is evacuated and replaced with hydrogen gas. After sufficient gas replacement in the growth reactor, the RF coil 16
Heat to approximately 700°C. Then, the raw material gas mixed to a desired concentration is introduced from the gas introduction duct 11,
Vapor phase growth is performed by flowing these mixed gases from the top to the bottom of the reactor. Since the thickness of the grown film is determined by the supply amount of Group III gases, namely trimethylgallium and trimethylaluminum, the film thickness can be controlled by examining the relationship between the growth time and the growth film thickness in advance and controlling the growth time. .

In products grown using this method, there is no displacement of the sample stage during each growth, and the reproducibility of the film thickness and composition of the grown layer is excellent. A semiconductor laser with excellent wavelength reproducibility was obtained.

Thus, according to this example, a grown layer having a desired composition with a uniform growth thickness can be stably obtained, so that the yield is improved and its industrial value is extremely large.

Note that the present invention is not limited to the embodiments described above. In the above embodiments, the organic metal and the hydrogen compound of arsenic were applied to the vapor phase growth of GaAtAs.
a AL It is also possible to apply to the vapor phase growth of compound semiconductors other than As. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a vapor phase growth apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a sample stand and a support stand for regulating the positional deviation of the sample stand. 1...Growth furnace, 2...Sample, 3...Sample stand, 6...
...Support stand, 9...Rotation mechanism, 10...Gas derivation duct, 11...Gas introduction duct. Agent: Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] A tapered concave portion is provided at the bottom of a removable high-frequency heating susceptor housed in a reactor, and a tapered convex portion that matches the shape is provided on the support base on the side that supports this. Vertical vapor phase growth equipment