JPH0613263Y2 - MOCVD equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a MOCVD apparatus capable of growing good-quality semiconductor crystals.

(B) Conventional Technology The MOCVD (Metal Organic Chemical Vapor Deposition) method has been extensively researched at present as a growth method that has excellent film thickness controllability and can grow high quality crystals.

FIG. 3 shows, for example, Journal of C-ysta.
L Growth, 68 (1984), P.I. 483-4
FIG. 89 is a cross-sectional view of a conventional MOCVD apparatus as shown at 89. In the figure, (1) is a reaction tube, (2) is a reaction tube (1)
To the reaction tube (1) for introducing the raw material gas, (4) is an exhaust tube communicating with the reaction tube (1), the other end is connected to an exhaust pump (not shown), The inside of the pipe (1) is decompressed and exhausted. (5) is a susceptor made of graphite or the like, which is arranged in the reaction tube (1). (6) is a substrate placed on the susceptor (5) on which a desired crystal is formed.
Reference numeral (7) is an RF (high frequency) coil provided around the reaction tube (1) where the susceptor (5) and the substrate (6) are located, and the susceptor (5)
The substrate (6) is heated via. (8) is a cooling tube provided around the reaction tube (1), which cools the reaction tube (1) by flowing water as shown by the arrow in the figure, and the undesired reaction of the raw material gas reacted in the air The reactant (11) is trapped off. Therefore, the crystal growth in such a conventional apparatus is performed by decomposing and depositing only the source gas reaching the substrate (6) on the substrate (6). That is, according to the above-mentioned structure, since the undesired reaction product reacted in the air does not adhere to the substrate (6), the conventional apparatus can form high quality crystals with few defects.

(C) Problems to be solved by the invention However, in such a conventional apparatus, the reaction product (11) adheres to the cooling pipe (1) at every growth, so that the reaction pipe above the substrate (6) is finally formed. The reactant (11) piled up on (1) falls and scatters, and this adheres on the growing substrate (6), thereby causing defects in the grown crystal. In addition, the stacked reactants (11) disturb the flow of the raw material gas in the reaction tube (1), resulting in uneven growth.

Therefore, conventionally, the reaction tube (1) had to be removed and washed with aqua regia every 30 to 40 times of growth. However, when the reaction tube (1) is washed, impurities such as H ₂ O remain in the reaction tube (1), so that the reaction atmosphere at the time of growth changes, and good crystals cannot be obtained. Therefore, after cleaning, it is necessary to perform preliminary growth 2-3 times, which causes problems such as an increase in running cost of the crystal growth step and a decrease in manufacturing yield.

(D) Means for Solving the Problems The present invention comprises a reaction tube, a gas introduction tube and a gas exhaust tube communicating with the reaction tube, and a cooling tube arranged along the inner wall of the reaction tube. In order to solve the above problem, the cooling pipe is slidable along the longitudinal direction of the reaction pipe, and / or a vibration means for vibrating the cooling pipe is connected to the cooling pipe. It is characterized by being

(E) Action The device of the present invention arranges a cooling tube in the reaction tube and makes it slidable, so that the cooling tube is attached to the cooling tube around the substrate every time the amount of reactant attached increases. By sliding, the cooling tube around the substrate can be made to have a clean surface free from reactants. Further, in the device of the present invention, a vibrating means is connected to the cooling pipe, and after growth, the cooling pipe is vibrated to remove the reactant attached to the cooling pipe on the upper part of the substrate and easily dropped or scattered. You can

(F) Embodiment FIG. 1 shows an embodiment of the device of the present invention, and the same parts as those of the conventional device of FIG. That is, (1) is a reaction tube, and (2) is a gas introduction tube communicating with the reaction tube (1). Further, (3) is a flange made of stainless steel, which is in close contact with the reaction tube (1) through an O-ring. Although omitted in FIG. 3, this is a well-known configuration. An exhaust pipe (4) communicates with the reaction pipe (1) through the flange (3). (5) is a susceptor, (6) is a substrate, and (7) is an RF coil, which are arranged in the same manner as the conventional device. (8) is a cooling pipe.
It is placed in the reaction tube (1). Such a cooling pipe (8) is a reaction pipe.
It has a cylindrical shape along the inner wall of (1), and in the state of FIG. 1, it is focused on two pipes on the flange (3) side of the susceptor (5) and taken out to the outside through the flange (3). There is. The cooling pipe (8) is in the longitudinal direction (left-right direction in the figure) in the reaction tube (1).
It is possible to slide to. In addition, the two tubes of the cooling pipe (8) are flanged via the O-ring like the normal reaction pipe (1).
It is in close contact with (3). (9) is a well-known multivibrator that generates a voltage having an arbitrary frequency, and (10) is a piezoelectric vibrator connected to the multihubrator (9). The piezoelectric vibrators (10) are respectively fixed to the two cooling pipes (8), and when a voltage is applied from the multivibrator (9), the cooling pipes (8) vibrate according to the frequency. The vibrating means is not limited to the multivibrator (9) and the piezoelectric vibrator (10), and other vibrating means such as a vibrating means using a motor may be used.

Thus, in the device of the present embodiment, during crystal growth, by flowing water through the cooling pipe (8) as in the conventional device, the undesired reaction product (11) produced by the reaction of the source gas in the air was generated. The reaction product (11) is trapped in the cooling pipe (8) to prevent the reactant (11) from adhering to the substrate (6). After the growth, H ₂ gas was flowed,
While heating the susceptor (5), the cooling pipe (8) is vibrated by using the multivibrator (9), and the reaction product (11) attached to the cooling pipe (8) above the substrate (6) is easily dropped or scattered. ) Is removed. At this time, if the frequencies of the two multivibrators (9) are changed to, for example, 5 KHz and 1 KHz, a standing wave is not generated in the cooling pipe (8) and the reactant (11) can be efficiently removed. As a result, the reactant (11) flying onto the substrate (6) during the growth is greatly reduced. However, not all the reactants (11) are removed by the vibration of the multivibrator (9) and the piezoelectric vibrator (10), and the reactants (1) that are not removed by the vibration as the number of growth increases (1
1) gradually accumulates. In this case, in the device of the present embodiment, the cooling pipe (8) is slid in the downstream direction of the raw material gas (rightward in the figure), so that the surface of the cooling pipe (8) on which the reactant (11) is not attached May be arranged around the substrate (6). As a result, crystal growth with few crystal defects can be performed without cleaning the reaction tube (1) for a long period of time.

FIG. 2 shows InGaP using the device of this example and the conventional device.
This is a measurement of the change in the crystal defect density with respect to the number of crystal growths during the production of crystals. In the figure, the solid line shows the apparatus of this embodiment, as described above, when the multivibrator (9) is used and the cooling pipe (8) is slid (A), and cooled at the number of times indicated by the arrow in the figure. Slide of tube (8) was performed. Also, the alternate long and short dash line indicates the multivibrator in this embodiment.
The case where only (9) is used is shown (B), and the broken line shows the case where the conventional device is used (C). As is clear from the figure, by using the device of this embodiment, the crystal defect density with respect to the number of times of growth can be significantly reduced as compared with the conventional device. Although not shown in the figure, the crystal defect density with respect to the number of times of growth can be reduced as compared with the conventional device also in the case where only the cooling pipe (8) is slid in the device of this embodiment.

(G) Effect of the Invention According to the device of the present invention, the cooling pipe arranged in the reaction tube is made slidable, and / or the vibration pipe is connected to the cooling pipe so that the cooling pipe is attached to the cooling pipe above the substrate. Since it is possible to suppress as much as possible the reactant that drops and scatters on the substrate during crystal growth, crystal growth with few crystal defects can be performed for a long period of time. Therefore, the manufacturing yield can be improved and the running cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the device of the present invention, FIG. 2 is a characteristic diagram showing a change in crystal defect density with respect to the number of times of growth in the device of the present invention and a conventional device, and FIG. 3 is a sectional view showing the conventional device. Is. (1) …… Reaction tube, (2) …… Gas introduction tube, (3) …… Flange, (4) …… Exhaust tube, (5) …… Susceptor, (6) …… Substrate,
(7) ... RF coil, (8) ... cooling tube, (9) ... multivibrator, (10) ... piezoelectric vibrator, (11) ... reactant.

Claims (1)

[Scope of utility model registration request] 1. A reaction tube, a gas introduction tube and a gas exhaust tube communicating with the reaction tube, and a cooling tube arranged along an inner wall of the reaction tube, wherein the cooling tube is of the reaction tube. An MOCVD apparatus, which is slidable in the longitudinal direction, and / or a vibration means for vibrating the cooling pipe is connected to the cooling pipe.