JPS6236812A - Semiconductor thin film vapor phase growth device - Google Patents

Abstract

PURPOSE:To allow a uniform growth of a semiconductor thin film with a small flow amount of gas by a method wherein a gas is introduced downward from an introduction inlet, turned the direction at the bottom of a coaxial tube, flows upwards, blows out from a small hole, and flows into a ring-shaped space which is formed by the coaxial tube with the bottom and the wall of the reaction tube. CONSTITUTION:The material gas and the carrier gas introduced from a gas introduction inlet 2 pass through a circular tube 5 provided just under the gas introduction inlet 2, are splashed onto the bottom of a coaxial tube with bottom 6 provided on the outer circumference of the circular tube 5, rise within the ring-shaped space 16 formed with the circular tube 5 and the coaxial tube with bottom 6, pass through plural small holes 7 bored near the upper end section of the coaxial tube with bottom 6, and are finally introduced into a ring-shaped space section 9 formed with a reaction tube 1 and the coaxial tube with bottom 6. Since a buffle plate 8 with small hole 10 is provided in the ring-shaped space section 9, the flow of the gases is further uniformed and introduced onto a crystalline substrate 15 on a rotating susceptor 4 to uniformly grow a semiconductor film with reaction such as thermal decomposition, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a semiconductor thin film vapor phase growth apparatus, and more specifically, the present invention relates to a semiconductor thin film vapor phase growth apparatus, and more specifically, a uniform gas flow is created in a bottomed turning tubular part, and a small gas flow rate is used to generate a uniform gas phase growth apparatus. The present invention also relates to a semiconductor thin film vapor phase growth apparatus capable of growing semiconductor thin films with few surface defects.

(Prior Art) Conventionally, a barrel-type vertical furnace is shown in FIGS. 3 to 5. As shown in FIG. 3, a polygonal truncated pyramid-shaped carbon susceptor (41), 1: in a reaction tube (40) has a substrate crystal (42).
is placed and heated to a predetermined temperature by high frequency induction using an external RF coil (43). Kas introduction date (45)
The raw material gas (46) introduced from the substrate crystal (42)
) The semiconductor thin film is deposited on the substrate crystal (42) by a reaction such as thermal decomposition near the surface, and then exhausted from the exhaust port (47). Note that the tube wall of the reaction tube is cooled by flowing a refrigerant through a cooling jacket (44), thereby suppressing decomposition of raw Negative 1 gas around the tube wall. On the other hand, the one shown in Fig. 4 has a hemispherical susceptor cap (4
8) on the susceptor (41) to open the gas inlet (45).
This is to avoid disturbing the flow of the raw material waste (46) that has been introduced.

However, the semiconductor thin film vapor phase growth apparatus shown in FIG. 3 and FIG. The speed is low, and convection tends to occur because the susceptor (41) is at a high temperature while the reaction tube (40) is at a low temperature. Therefore, in order to grow a uniform semiconductor thin film, the flow of the raw material gas must overcome convection and become laminar, but this requires a large gas flow rate, which reduces the yield. Not only that, if there is convection, reaction products will adhere to the upper part of the reaction tube (40), which will peel off during thin film growth and form the substrate crystal (42).
) adheres to L and contributes to surface defects.

Furthermore, the one shown in FIG. 5 has a structure in which the raw material gas (46) is blown out in a jet form from a nozzle (49) provided in one part of the susceptor (41), but the -F part of the nozzle (49) There is a problem in that it is difficult to obtain a steep doping profile because the gas in the space cannot be replaced quickly.

Therefore, in view of the above-mentioned viewpoint, the present inventors previously proposed a semiconductor thin film vapor phase growth apparatus (Japanese Patent Application No. 58-206294) as shown in FIGS. 6 and 7. In this example, the portion of the reaction tube (21) from the gas inlet (22) to the top surface of the susceptor (23) is constructed with a concentric tube portion with a bottom on the inside, and the portion between the reaction tube portion on the outside and this portion An annular space part (24
), and a baffle plate (25) is provided in this annular space (24), which allows the raw material gas to flow uniformly into the susceptor at a relatively high velocity. (23) J- is supplied to the crystal substrate (26)l.

(Problem to be solved by the invention) However, in the device shown in Fig. 6, three gas inlets are arranged at equal intervals.
When we conducted an experiment with the baffle plate (25), we found that the gas blowing speed at the gas inlet (22) was too high.
Despite this, the gas velocity is high just below the gas inlet (22) and slow between the gas inlets, resulting in uneven gas flow, which sometimes causes the gas to curl.

Therefore, the present invention is based on such patent application No. 58-2062.
The purpose of this paper is to improve the apparatus shown in No. 94 and create a uniform gas flow in concentric tubular sections, and to propose a semiconductor thin film vapor phase growth apparatus that has a small gas flow, is uniform, and has few surface defects.

(Means for solving the problem) The above object is to provide a circular gas inlet tube from the gas inlet of the reaction tube toward the susceptor in a semiconductor thin film vapor phase growth apparatus having a barrel-type vertical furnace. A concentric tube with a bottom is provided to cover the circular tube, and the upper end of the concentric tube with a bottom is fixed to the reaction tube, and a plurality of small holes are bored in the vicinity of the tube, so that the gas flows downward from the inlet side. The liquid is introduced in the opposite direction, changes direction at the bottom of the bottomed concentric tube, flows upward, blows out from the plurality of small holes, and then flows out into the annular space formed by the bottomed concentric tube and the wall of the reaction tube. This could be achieved using a semiconductor thin film vapor phase growth apparatus featuring the following characteristics.

(Example) An example of an embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, the symbol (A) indicates a semiconductor thin film vapor phase growth apparatus according to the present invention, and this semiconductor thin film vapor phase growth apparatus (A
) has a gas inlet (2) (inner diameter 2 r o ) at the top,
Reaction tube (1) equipped with an exhaust port (3) at the bottom (inner fp
2r5), a polygonal truncated pyramid-shaped susceptor (4) rotatably provided inside the reaction tube (1), and a circle provided from the gas inlet (2) toward the susceptor (4). This circular tube (5) is formed by a tube (5).
) is provided with a bottomed concentric tube (6) whose upper end is fixed to the reaction tube (1). -F circular tube (5) is covered with this bottomed concentric tube (6).

A plurality of small holes (7) are bored near the upper end of the bottomed concentric tube (6). (8), (8)...ha"
- The annular space between the reaction tube (1) and the bottomed concentric tube (6) (
This baffle plate (8) shows the baffle plate provided in 9).
, (8)... have small holes (10), (io) at predetermined positions.
... has been drilled.

On the other hand, around the reaction tube (1) shown in - is a cooling jacket) (
11) is provided, and a refrigerant inlet (12) is provided at the lower part on the negative side, and a refrigerant discharge r1 (13) is provided at the other side. Further, an RF coil (14) is disposed on the outside of the cooling jacket (11). (15
) indicates the crystal substrate on the susceptor (4).

Since the semiconductor thin film vapor phase growth apparatus (A) is configured as described in -1-, in its operation, first, the raw material gas and carrier gas introduced from the gas inlet (2) are The spray passes through the circular tube (5) provided directly below the circular tube (5) and hits the bottom of the bottomed concentric tube (6) provided on the outer periphery of the circular tube (5). It rises in the annular space (16) with the bottomed concentric tube (6), passes through a plurality of small holes (7) bored near the upper end of the bottomed concentric tube (6), and reacts. It is introduced into the annular space (9) formed by the tube (1) and the bottomed concentric tube (6). This annular space (9) has a small hole (10),
(10), (10)... are perforated on the baffle plate (8
), (8)... are provided, so that the gas flow is further made uniform, and the susceptor (4') is in a rotating state.

is introduced into the crystal substrate (15), and a semiconductor thin film is uniformly grown by reactions such as thermal decomposition.

On the other hand, regarding the susceptor, the upper surface of the susceptor (4) is arranged parallel to the bottom of the bottomed concentric tube (6).

In addition, -1- of this bottomed concentric tube (6) and susceptor (4)
The distance d2 between the surfaces is 2 mm or less, which allows the susceptor (
4) can freely rotate without contacting the bottom of the bottomed concentric tube (6). Further, the outer diameter 2r4 of the bottomed concentric tube (6) is set to be less than or equal to the diameter p 2 r6 of the inscribed circle of the upper surface of the susceptor (4), but it is set to a value as close to 2 r e as possible. Furthermore, the inner diameter 2 r 3 of the bottomed concentric tube (6) and the outer diameter 2 of the circular tube (5)
It is desirable that r2 and the inner diameter 2r1 satisfy the following relationship so that the gas passage cross-sectional areas are equal.

3' 2 □'' - Gap d between the circular tube (5) and the bottom of the bottomed concentric tube (6)
1 is desirably made as small as possible because it is necessary to increase the gas velocity so that the gas is not heated by heat from the upper part of the susceptor (4).

Next, what is shown in FIG. 2 shows the other side of the embodiment of the semiconductor thin film vapor phase growth apparatus (A) according to the present invention, and in this figure, the same symbols as in FIG. 1 mean the same things. In this example, a thin tube (1) for introducing carrier gas is placed in the center of the circular tube (5a).
7), the tip of this introduction thin tube (17) is opened at the bottom of the bottomed concentric tube (6a), and the base end is exposed and fixed from the side of the gas introduction port (2a). There is. Thereby, the carrier gas can be blown onto the susceptor (4), and the above-mentioned low and low concentric tube (6a) and this susceptor (4a) can be blown.
), gas can be prevented from stagnation in the gaps between the two, and a steeper interface can be obtained.

(Operations and Effects of the Invention) The semiconductor thin film vapor phase growth apparatus according to the present invention as described in 2. has a circular tube extending from the gas inlet of the reaction tube toward the susceptor, and a bottomed tube covering the circular tube. A concentric tube is provided, and one end of the bottomed concentric tube is fixed to and resides in the reaction tube, and a plurality of small holes are bored in the vicinity thereof, while reacting with the bottomed concentric tube. A plurality of small holes are bored in the annular space between the tube and a Tuffle plate as appropriate. Therefore, (1) the raw material gas and carrier gas introduced from the gas inlet are made uniform and guided to the crystal substrate on the susceptor, and the semiconductor thin film is uniformly grown with a small gas flow rate, improving the yield ( 2) The doping profile and the steepness of the hetero interface are improved.

(3) Reaction organisms no longer adhere to the L portion of the reaction tube, and surface defects on the substrate crystal caused by reaction products are eliminated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of an embodiment of a semiconductor thin film vapor phase growth apparatus according to the present invention, FIG. 2 is a sectional view showing another example of the semiconductor thin film vapor growth apparatus according to the present invention, and FIGS. 3 to 7 are sectional views showing a conventional example. FIG. Symbol (A)... Semiconductor thin film vapor phase growth apparatus (1)...
Reaction tube (2)...Gas inlet (3)...Exhaust [1
(4)...Susceptor (5)...Circular tube (6)...
Bottomed concentric tube (8)...Eight full plate (11)...Cooling jacket (14)...RF coil (Fig. 1 N\r Fig. 6 Fig. 7 °1). O. Q 0 23゜ Oo Procedural amendment (voluntary) March 11, 1985 Display of the case of Michibu Uga, Director General of the Agency 1985 Patent Application No. 176170 Name of the invention Case of a person who corrects semiconductor thin film vapor phase growth equipment Relationship Patent applicant address 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Name (52
9) Furukawa Electric Co., Ltd. 4.1 Address 1 Address 5.7 6. Number of inventions increased by amendment 07. Column 8 of "Detailed explanation of the invention" of the specification subject to amendment, Contents of amendment (1) ) Page 2 of the specification, line 5 f) "Uniformly in the concentric tube with a bottom" is corrected to "uniformly in the annular space created by the concentric tube with a bottom and the reaction tube." (2) Page 3, lines 16-17 of the same book
Correct the phrase ``Not only does it not flow well, but also convection occurs'' to ``As a result, the raw material yield does not increase, and convection also occurs''. -Rinichi

Claims (2)

[Claims] (1) In a semiconductor thin film vapor phase growth apparatus having a barrel-type vertical furnace, a circular gas introducing tube is provided from the gas inlet of the reaction tube toward the susceptor, and a concentric tube with a bottom is provided to cover this circular tube, The upper end of this bottomed concentric tube is fixed to the reaction tube, and a plurality of small holes are bored in the vicinity thereof,
The gas is introduced downward from the inlet side, changes direction at the bottom of the bottomed concentric tube, flows upward, and then blows out from the plurality of small holes, forming an annular shape formed by the bottomed concentric tube and the wall of the reaction tube. A semiconductor thin film vapor phase growth apparatus characterized by a device that allows the flow to flow into space. (2) Semiconductor thin film vapor phase growth according to claim 1, characterized in that a baffle plate with a plurality of small holes is provided in the annular space between the bottomed concentric tube and the reaction tube. Device.