JPH0691011B2 - Semiconductor thin film vapor phase growth equipment - Google Patents

Description

The present invention relates to a semiconductor thin film vapor phase growth apparatus,
Specifically, in a semiconductor thin film vapor phase growth apparatus having a barrel type vertical furnace, a concentric tubular structure is provided between a gas inlet and a susceptor so that a semiconductor thin film can be uniformly grown with a small gas flow rate. The reaction furnace of the semiconductor thin film vapor phase epitaxy apparatus is roughly classified into a horizontal type and a vertical type. Among them, a so-called barrel type vertical type furnace having a barrel type susceptor is said to have excellent mass productivity.

1 to 3 show a conventional barrel type vertical furnace, in which a polygonal truncated pyramidal carbon susceptor, a so-called barrel type susceptor (2) in a reaction tube (1) is shown in FIG. The substrate crystal (3) is placed, and the outside is subjected to high-frequency heating by the RF coil (4), and a cooling jacket (5) is provided to allow a coolant such as cooling water to pass through the cooling jacket to control the temperature of the reaction tube wall. The source gas (7) introduced from the upper gas introduction port (6) causes a reaction near the surface of the susceptor (2) to grow a semiconductor thin film on the substrate crystal (3), and to grow a uniform thin film. Therefore, crystal growth is performed while rotating the susceptor (2). (8) is an exhaust port. The barrel type vertical furnace shown in FIG. 2 has the same structure as that shown in FIG. 1, but a hemispherical cap (9) is placed on the susceptor to prevent turbulence of gas flow on the upper surface of the barrel type susceptor. Has been.

However, in the barrel type vertical furnace shown in FIGS. 1 and 2, there is a large free space in the upper part of the susceptor. In this part, the gas cross-sectional area is large, so the gas velocity is small, and the susceptor Is high temperature, but the reaction tube is low temperature, so convection easily occurs. Therefore, in order to achieve uniform growth of the semiconductor thin film, it is necessary to overcome the convection of the gas to form a laminar flow, but for that purpose, a large gas flow rate is required, and the yield cannot be increased. Further, it is not preferable to provide the cap shown in FIG. 2 because the susceptor portion becomes large and the apparatus becomes large when the substrate crystal exchanging front chamber is provided.

In the apparatus shown in FIG. 3, the reactor structure including the reaction tube is almost the same as the former two, but the source gas is guided from the gas inlet (11) provided in the susceptor support rod (10) and the nozzle (12 )
(12 ') has a jet-like structure so that a large gas velocity can be obtained with a small gas flow rate.
However, this device has a complicated structure and the gas in the upper part of the nozzle is not replaced promptly. The doping gas remaining in the film is taken into the high-purity thin film, which makes it difficult to obtain a sharp doping profile.

The present invention has been made to address the drawbacks of the conventional semiconductor thin film vapor phase growth apparatus having a barrel type vertical furnace, and it is possible to obtain a uniform semiconductor thin film with a small gas flow rate without complicating the apparatus. It is designed to grow.

That is, the present invention relates to a semiconductor thin film vapor phase growth apparatus having a barrel type vertical furnace, in which a portion from the gas inlet of the reaction tube to the upper surface of the susceptor is constituted by a concentric tube portion having a bottom inside and the reaction tube outside. And a gas rectifier consisting of a baffle plate are provided in the annular space to form an annular space between them and the source gas is made uniform at a relatively large speed. It is supplied to the substrate crystal on the susceptor. As the concentric tubular structure, a concentric cylindrical or concentric conical tubular structure is usually used. The size of the concentric tube is preferably such that the diameter of the lower end portion thereof is substantially the same as the diameter of the upper end portion of the asceptor.

The present invention will be described in detail below with reference to embodiments shown in the drawings.

FIG. 4 shows an example of the barrel type vertical furnace of the present invention.
The upper structure of the reaction tube (21) is a concentric cylindrical structure having an annular space portion (23) by forming the inside of the reaction tube (21) with a bottomed concentric cylindrical portion (22). ) Is a gas rectifier (25) consisting of multiple baffle plates (24)
Is provided.

The raw material gas (27) introduced from the gas introduction port (26) is mixed while passing through the gas rectifier (25), and at the same time, adjusted to a uniform gas velocity, and the barrel type susceptor (28) in a rotating state. Guided by the upper substrate crystal (29), the semiconductor thin film is uniformly grown. In addition, (30) is a cooling jacket,
(31) is an RF coil, and (32) is an outlet. In this embodiment, since only one gas inlet (26) is provided, there will be a considerable difference in gas velocity between the gas inlet side and the opposite side. The velocity is adjusted to be uniform in the pass area.

Further, not only one gas inlet but also a plurality of gas inlets may be provided in the annular portion at the upper end of the reaction tube (21) at equal intervals.

In such a barrel type vertical furnace of the present invention, there is no free space above the susceptor (28), and the gas inlet (26)
Since the passage area from the top to the upper surface of the susceptor (28) is small, a stable gas flow with a relatively large velocity can be obtained with a small flow rate, and as a result, a uniform semiconductor thin film can be grown on the substrate crystal (29). Also, the yield is improved. Furthermore, since the space volume through which the gas passes from the gas inlet (26) to the upper surface of the susceptor (28) is small, gas replacement in this region can be performed in a short time, so that the steepness and steep heterogeneity of the doping profile can be achieved. An interface is obtained.

Next, FIG. 5 shows another embodiment of the present invention.
Replace the upper structure of the reaction tube (21 ') with the bottomed concentric cone tube (2
2 ') has a concentric conical tubular structure having an annular space portion (23'), and the upper part of the reaction tube (21 ') and the concentric conical tube part (22') have a polygonal pyramid of the susceptor at the lower part thereof. It has the same inclination as that of the table, and the upper bent portion of the reaction tube (21 ') is designed to substantially coincide with the position of the upper surface of the susceptor.

[Brief description of drawings]

1 to 3 are sectional views showing a conventional example of a barrel type vertical furnace of a semiconductor thin film vapor phase growth apparatus, and FIGS. 4 and 5 are semiconductor thin film vapor phases of the present invention shown in Examples, respectively. It is sectional drawing of the barrel type vertical furnace of a growth apparatus. 21, 21 '…… Reaction tube 22 …… Concentric cylindrical section 22´ …… Concentric conical tube section 23, 23 ′ …… Annular space section 24 …… Baffle plate 25 …… Gas rectifier 26 …… Gas inlet 27 …… Source gas 28 …… Barrel type susceptor 29 …… Substrate crystal 30 …… Cooling jacket 31 …… RF coil 32 …… Exhaust port

Claims (2)

[Claims] 1. In a semiconductor thin film vapor phase growth apparatus having a barrel type vertical furnace, a portion from a gas inlet of a reaction tube to an upper surface of a susceptor is formed by a concentric tube portion having a bottom inside and the reaction on the outside. Semiconductor thin film vapor phase growth apparatus having a concentric tubular structure in which an annular space is formed between the tube and the tube. 2. The semiconductor thin film vapor phase growth apparatus according to claim 1, wherein the concentric tubular structure is one of a concentric cylindrical structure and a concentric conical tubular structure.