JPH0195517A - Apparatus and method for manufacturing compound semiconductor - Google Patents

Abstract

PURPOSE:To make further uniform the thickness of a semiconductor film by rotating for vapor phase growth a susceptor around an axis perpendicular to the upper surface of the susceptor, the susceptor being disposed at an angle less than 45 deg. with respect to the horizontal flow of stock gas for a compound semiconductor. CONSTITUTION:A susceptor 2 is provided, which is rotatably mounted in the inside of a lateral reaction table 1, on the upper surface of which a substrate 3 for vapor phase growth is placed. The susceptor 2 is supported by a shaft 5 such that the upper surface thereof is slanted at an angle less than 45 deg. with respect to a horizontal plane, and is rotated around the shaft 5. Vapor phase growth is performed by rotating the susceptor 2 around the central axis thereof. Hereby, a compound semiconductor can uniformly be grown at each location on the substrate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a compound semiconductor manufacturing (MOCVD) device and method for vapor phase growth using a reaction tube, and particularly relates to a compound semiconductor manufacturing (MOCVD) device and method for vapor phase growth using a reaction tube.
(2) The present invention relates to a compound semiconductor manufacturing apparatus using a horizontal reaction tube for epitaxially growing organometallic compounds of the V, V, and Vl groups on a substrate.

[Prior Art] Semiconductor manufacturing methods by vapor phase growth (MOCVD) using organometallic compounds that have been developed can be broadly classified into two types. That is, one uses a vertical reaction tube, and the other uses a horizontal reaction tube. This is a method in which the gas flow is directed downward and hits the semiconductor growth substrate 3 almost vertically.
In the latter method, as shown in FIG. 4, a gas of an organometallic compound is flowed horizontally in a horizontal reaction tube 1, and this gas flow is directed toward a semiconductor growth substrate 3 placed diagonally. . In FIGS. 3 and 4, 2' and 2' are susceptors, and 6 is an exhaust pipe.

In the conventionally developed semiconductor manufacturing method using the vapor phase growth method using the vertical reaction tube shown in FIG. 3, it is usually necessary to heat the substrate 3. Since turbulence tends to occur in the gas flow, it is difficult to produce a semiconductor with a uniform composition, making it difficult to obtain a semiconductor with good performance.

As a vapor phase growth method that does not have such difficulties, a reaction apparatus that can prevent the generation of turbulent flow due to heat in the vicinity of the organometallic gas substrate 3 is shown in FIG. A method using the horizontal reaction tube 1 was developed, and by oriented the semiconductor film growth substrate 3 at an angle to the gas flow, the gas flow was made laminar. It is said that the problems of the semiconductor film growth apparatus used have been solved.

[Problems to be Solved by the Invention] As mentioned above, when manufacturing a compound semiconductor using a horizontal reaction tube, in order to minimize turbulence in the flow of reactive gas, it is conventional to place the substrate in the flow of reactive gas. It is installed at an inclination angle of 45° or less with respect to the axis. However, when making compound semiconductors using this method, it is inevitable that there will be a considerable distance from the front end of the substrate placed in the reaction tube to the back end, and crystals formed at the front end of the substrate and crystals formed at the back end of the substrate will inevitably be separated by a considerable distance. It was inevitable that the structure would be different from that of the crystals that had been produced.

In conventionally developed horizontal reaction tubes, or horizontal furnaces, the vapor phase growth rate is high on the upstream side of the raw material gas flow, so the raw material concentration tends to be attenuated downstream of the substrate and the raw material composition tends to be different from that on the upstream side. There are some drawbacks, and it cannot be said to be sufficient for producing semiconductor films with precise epitaxial growth, stoichiometry control, and lattice mismatch control. For example, if a GaAs substrate of 1c+n angle is used and the substrate is not rotated as in the comparative example described later, but the other conditions are exactly the same as the operating conditions of the device of the present invention, and a compound semiconductor is produced, GaAs The lattice mismatch rate of an epitaxial thin film grown on a substrate varies as much as ±0.25% depending on the location of the grown film. This is considered to be due to non-uniformity in the concentration distribution of each reactive gas component on the substrate when a horizontal reactor is used.

This means that the concentration ratio X of the organometallic compounds used in the reaction tube is the concentration of the organometallic compounds A and h used respectively [A],
[B] is expressed by the relationship, where the concentration ratio X and the lattice mismatch rate Δa /
This is because a satisfies a linear relationship.

As a way to prevent such inconveniences, a supplementary gas introduction pipe is installed near the substrate in addition to the raw material gas inlet, and the gas inlet is placed upstream of the substrate to eliminate the difference in gas concentration downstream of the substrate and to ensure a uniform gas composition. However, this method of introducing an auxiliary gas has the disadvantage that the structure of the reactor itself is extremely complicated, and the growing semiconductor film is likely to have non-uniform film thickness. Ta.

[Means for Solving the Problems] The present inventors have conducted studies to develop a semiconductor vapor phase growth apparatus that has the advantages of a horizontal reaction tube and is less likely to cause the above-mentioned disadvantages of the horizontal reaction tube. As a result, the present invention was completed. A feature of the present invention is that a susceptor is installed perpendicularly to the upper surface of the horizontal reaction tube, which is installed at an angle of 45 degrees or less with respect to the horizontal flow direction of the gas, in a horizontal reaction tube that horizontally supplies raw materials for compound semiconductors in a gaseous state. The process involves vapor phase growth while rotating around a central axis. That is, according to the present invention, in a vapor phase growth apparatus for compound semiconductors, a material for compound semiconductors is supplied in a vapor phase into a horizontal reaction tube, and a semiconductor is grown in vapor phase on a substrate on a susceptor provided in the reaction tube. , the horizontal reaction tube is arranged so that the compound semiconductor raw material is supplied horizontally, the upper surface of the susceptor is inclined at an angle of 45@ or less with respect to the horizontal plane, and the upper surface of the susceptor is inclined with respect to the upper surface of the susceptor at an angle of 45@ or less There is provided a compound semiconductor manufacturing apparatus characterized in that a means for rotating the susceptor about a vertical central axis is provided; In a compound semiconductor manufacturing method in which a semiconductor is vapor-phase grown on a substrate on a susceptor provided in There is provided a compound semiconductor manufacturing method characterized in that the susceptor is rotated about a central axis perpendicular to the upper surface of the susceptor while being tilted at the following angle to perform vapor phase growth on the substrate.

[Function] As described above, in the present invention, the upper surface of the susceptor on which the substrate is placed in the horizontal reaction tube is inclined at an angle of 45@ or less with respect to the horizontal plane, and the susceptor is further rotated around its central axis. Since the vapor phase growth is performed while slowing down, the compound semiconductor grows uniformly at each position on the substrate.

In addition, since the reaction tube used in the present invention is a horizontal reaction tube,
Because the flow of the gaseous material, which is a raw material for compound semiconductor manufacturing, inside the reaction tube can be made as a laminar flow, it is possible to prevent airflow turbulence due to the convection of reactive gas near the substrate, as in the case of using a vertical reaction tube. Since this does not easily occur, a compound semiconductor having a desired composition and crystal structure can be produced.

[Embodiments] Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the main parts of the compound semiconductor manufacturing apparatus of the present invention,
That is, it is a side sectional view of a portion of the reaction tube.

A susceptor 2 rotatably mounted inside the horizontal reaction tube 1 is provided, and a substrate 3 on which vapor phase growth is to be performed is placed on the upper surface of the susceptor 2. The susceptor 2 has a support shaft 5 such that its upper surface is inclined at an angle of 45° or less with respect to the horizontal plane.
It is supported by

In the illustrated example, the upper surface of the susceptor 2 is inclined by 5'' with respect to the horizontal plane, but the larger the angle, the higher the efficiency of vapor phase growth, so it can be increased or decreased as necessary. This is an opening 1a for an inlet, into which raw materials are introduced from a device not shown.An exhaust pipe 6 is inserted into the opening 1b at the right end of the reaction tube 1 in a telescoping manner.In the center of the exhaust pipe 6 is a rotating A shaft 4 is rotatably attached, and a gear 7 is attached to the left side of the shaft 4. This rotating shaft 7 is connected to a motor as a drive source (not shown) outside the exhaust pipe 6, and its rotational drive is The force is transmitted to the gear 7. The gear 7 engages with the uneven teeth 2b provided around the susceptor 2, so that rotation of the gear 7 causes
The susceptor 2 will rotate around the support shaft 5. Note that this support shaft 5 is perpendicular to the upper surface 2a of the susceptor 2 and coincides with the central axis of the susceptor 2.

The horizontal reaction tube 1 is made of quartz glass and has an inner diameter of 100 mm.

A length of 850 mm is used. The susceptor 2 itself is made of carbon, and its upper surface 2a is provided with a recess (not shown), and by placing the substrate 3 in this recess, the substrate 3 will be displaced during rotation of the susceptor 2. This is prevented. Note that the outer surface of the susceptor 2 is coated with silicon carbide.

The tip of the support shaft 5 is configured to fit into the center hole 2c provided on the lower surface of the susceptor 2, and the support shaft 5 is made of quartz glass. Further, the gear 7, the tooth portion 2b, and the rotating shaft 4 are also made of quartz glass. The reason why quartz glass is used in the parts that generate rotational friction is that by using a material that is inert to reactive gases, it prevents the adsorption of reactive gases and 1. This is to prevent unnecessary dust from being generated by using a material with high hardness.

A 1 cm square GaAs substrate was used as the substrate 3, and the inclination angle with respect to the horizontal gas flow axis was set to 5'' as described above.The rotational speed of the susceptor 2 was 1r, p, 1.
The semiconductor growth temperature was 700° C. and the pressure was 2° Torr. The homogeneity and quality of the manufactured semiconductors are not directly affected by the rotational speed of the susceptor, but if the rotational speed is too high, dust, etc. will be generated at parts that cause friction, such as the gear 7, rotating shaft 4, and support shaft 7. This is not desirable. Therefore, it is desirable to have a value of about 3 r, p, m or less.

Among organometallic compounds, trimethylgallium (
TMGa), )limethylindium (TMIn), V
Arsine (As Hs ) and phosphine (PH3) were used as the group compounds, the V1m ratio was set to 100, and [T
A compound semiconductor was prepared under the conditions of a gas flow rate of 24 cm/s and a ratio of M Ga] + [TMIn] as shown in the table, and the degree of lattice mismatch (Δa/a
) are shown in the table.

From the results shown in the table, it can be seen that when the compound semiconductor manufacturing apparatus of the present invention is used, the lattice mismatch rate can be made extremely small.

In the above embodiment, only one substrate 3 was used, but it is also possible to arrange a plurality of substrates on the upper surface 2a of the susceptor 2. The inclination angle of the substrate 3 with respect to the flow of the reactive gas, which is the compound semiconductor raw material, must be 45" or less. If this inclination angle becomes too large, turbulence will occur in the flow of the reactive gas, and it will not be uniform. This makes it difficult to manufacture a compound semiconductor with excellent properties.Usually, this inclination angle is preferably 30 degrees or less as shown in the above embodiment, and may be 0@.

[Effects of the Invention] As explained in detail above, according to the compound semiconductor manufacturing apparatus and method of the present invention, the upper surface of the susceptor in the horizontal reaction tube is inclined at an angle of 45@ or less with respect to the horizontal direction, and the susceptor is Since vapor phase growth is performed on the substrate placed on the top surface of the susceptor while rotating around the central axis, it is possible to perform extremely uniform vapor phase growth compared to conventional equipment and methods, resulting in a homogeneous This makes it possible to manufacture compound semiconductors with a wide range of properties. That is, the variation in lattice mismatch depending on the location of the epitaxially grown crystal can be significantly improved compared to the lateral MOCVD method without rotation. Furthermore, there is also the effect that the yield can be improved during mass production.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing the main parts of an embodiment of the compound semiconductor manufacturing (MOCVD) apparatus of the present invention, FIG. 2 is a plan view for explaining the rotation mechanism of the susceptor in FIG. 1, and FIG. 4 is a side sectional view showing the main parts of a conventional vertical compound semiconductor manufacturing apparatus, and FIG. 4 is a side sectional view showing the main parts of a conventional horizontal compound semiconductor manufacturing apparatus without a rotation mechanism. 1.゜...Reaction tube 2.2', 2'...Susceptor 2a...Susceptor top surface 2b...Tooth portion 3...
・Platform 4.4'... Rotating shaft 5...
Susceptor support shaft 6.6'...Exhaust pipe 7...Gear Inventor Kawanishi Hideo Fuuzai Seitoshi Akito Applicant Mitsubishi Rayon Co., Ltd.

Claims (7)

[Claims] (1) In a vapor phase growth apparatus for compound semiconductors, which supplies raw materials for compound semiconductors in a vapor phase into a horizontal reaction tube and causes the semiconductor to grow in vapor phase on a substrate on a susceptor provided in the reaction tube, the compound, The horizontal reaction tube is arranged so that semiconductor raw materials are supplied in a horizontal direction, and the upper surface of the susceptor is inclined at an angle of 45 degrees or less with respect to the horizontal plane, and the upper surface of the susceptor is inclined at an angle of 45 degrees or less with respect to the horizontal plane, and A compound semiconductor manufacturing apparatus, comprising means for rotating the susceptor about a central axis. (2) The upper surface of the susceptor is approximately 30 degrees relative to the horizontal plane.
2. The compound semiconductor manufacturing apparatus according to claim 1, wherein the compound semiconductor manufacturing apparatus is inclined at an angle of .degree. (3) The rotating means includes a rotating shaft that transmits power from a drive source external to the reaction tube, a gear attached to one end of the rotating shaft, and a gear attached to the outer periphery of the susceptor. 2. The compound semiconductor manufacturing apparatus according to claim 1, further comprising teeth that engage with each other. (4) The compound semiconductor manufacturing apparatus according to claim 3, wherein the rotating shaft, the gear, and the tooth portion are made of quartz glass. (5) A compound semiconductor manufacturing method in which a compound semiconductor raw material is supplied in a vapor phase into a horizontal reaction tube, and a semiconductor is grown in a vapor phase on a substrate on a susceptor provided in the reaction tube. The susceptor is supplied horizontally into the horizontal reaction tube, and the susceptor is rotated about a central axis perpendicular to the top surface of the susceptor while the top surface of the susceptor is inclined at an angle of 45 degrees or less with respect to the horizontal plane. A method for manufacturing a compound semiconductor, comprising performing vapor phase growth on the substrate. (6) The upper surface of the susceptor is approximately 30 degrees relative to the horizontal plane.
6. The compound semiconductor manufacturing method according to claim 5, wherein the susceptor is rotated while being tilted by .degree. (7) Add the susceptor to 3r. p. m. 6. The compound semiconductor manufacturing method according to claim 5, wherein the compound semiconductor manufacturing method is rotated at the following speed.