JPH10163115A - Vapor growth device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the uneveness of the thickness and carrier concentration of a semiconductor film within a wide region of a susceptor by making symmetrical and uniform the flow of a feed gas in a reactor container during the growth of a semiconductor deposition film, and at the same time stabilizing the decomposition of the feed gas on the susceptor. SOLUTION: A feed gas is supplied from a gas introduction port 7 provided at the reverse side of a susceptor 4, is diffused radially on the reverse side of the susceptor, allowed to flow on the surface of the susceptor 4 along a channel formation body 20 provided on the susceptor 4, and is discharged from an exhaust port 10 provided at the center of the susceptor 4. Also, by heating or cooling the channel formation body 20 as needed, temperature control in the diameter direction of the susceptor 4 is performed precisely and easily, thus extremely reducing uneveness of the thickness of a deposition film and the characteristics of a semiconductor film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vapor phase growth apparatus for performing metal organic chemical vapor deposition (MOCVD), which is a kind of vapor phase growth method.

[0002]

2. Description of the Related Art In general, the MOCVD method uses a low-cost substrate because crystals can be grown on a heterogeneous substrate.
A large amount of crystals can be supplied at low cost. FIG. 2 shows a cross-sectional structure of a conventional vertical vapor phase growth apparatus. In the figure, reference numeral 1 denotes a reaction vessel, 2 denotes a reaction gas outlet, and 4 denotes a semiconductor substrate provided in the reaction vessel. 5 is a heating device for heating the susceptor 4, 7 is a raw material gas inlet, 6 is a drive shaft for supporting and rotating the susceptor 4, and includes a drive motor 9 and a gear mechanism 8. Rotate. Reference numeral 10 denotes a material gas exhaust port.

Next, the operation will be described. The susceptor 4 provided in the reaction vessel 1 is heated to a predetermined temperature (500 to 800 ° C.) by a heating device 5 provided in the reaction vessel.
Heated. At this time, the gas sent from the raw material gas inlet reaches the substrate 3 placed on the susceptor 4 from the gas outlet 2 and grows a semiconductor crystal film on the surface of the substrate 3 by thermal decomposition. Further, the source gas is exhausted from the exhaust port 10 through the gap 11 between the reaction vessel 1 and the susceptor 4. Here, during the film growth, the susceptor 4 is rotated by the rotation of the drive shaft 6 to achieve uniform crystal growth in the rotation direction.

[0004]

The conventional vertical vapor phase epitaxy apparatus is constructed as described above,
Is located at the center of the susceptor, the gas flow is uniform near the outlet, but it is difficult to obtain a uniform flow at the outer periphery of the susceptor, and the position of the gas exhaust port 10 is Due to the asymmetry, when the diameter of the susceptor is large, or when a thin deposited film is required, the thickness of the deposited film may vary due to uneven gas flow. Furthermore, since the introduction gas outlet 2 has a nozzle shape, there is a problem that the decomposition reaction of the raw material is not stable in the vicinity of the outlet, and the carrier concentration in the deposited film varies. The present invention makes the flow of the source gas in the reaction vessel symmetric and uniform during the growth of the semiconductor deposited film, stabilizes the decomposition of the source gas on the susceptor, and increases the thickness of the semiconductor film in a wide area of the susceptor. And to reduce the variation in carrier concentration.

[0005]

According to a first aspect of the present invention, there is provided a vapor phase growth apparatus according to the present invention, wherein a raw material gas is supplied from a gas inlet provided on a back side of a susceptor. Once diffused radially on the susceptor substrate mounting back surface, it flows on the susceptor surface along the gas flow path forming body provided on the susceptor substrate mounting surface, and out of the reaction vessel from the exhaust port provided in the center of the susceptor. It is characterized by exhausting.

[0006] A vapor phase growth apparatus according to a second aspect of the present invention is characterized in that, in the first aspect of the invention, the flow path forming body has a structure capable of heating or cooling.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 shows an embodiment of the present invention, and FIG.
This will be described in detail based on FIG. In FIG. 1, the same components as those in FIG. 2 according to the conventional method are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 will be described taking as an example a case where a GaAs film is epitaxially grown on a GaAs substrate by MOCVD. A raw material gas composed of trimethylgallium (TMG) and arsine (AsH ₃ ) was supplied from a gas supply device (not shown) through a gas inlet 7 provided in the lower cylindrical portion 1b of the reaction vessel 1 using hydrogen gas as a carrier. The reaction gas flows from the lower part of the susceptor drive shaft 6 along the drive shaft 6, and diffuses on the back surface of the susceptor 4 in the direction in which the diameter of the susceptor increases, and then flows between the substrate mounting surface of the susceptor 4 and the flow path forming body 20. It flows through the formed flow path and is discharged from an exhaust port 10 provided at the center of the susceptor 4. As shown in FIG. 1, the flow path forming body 20 is provided above the susceptor 4 and is fixed to the flange 16 provided on the container 1.
In order to make the flow of the source gas on the substrate mounting surface of the susceptor 4 uniform, the shape of the flow path forming body 20 is set such that the distance between the susceptor 4 and the lower surface of the flow path forming body 20 is from the outer periphery of the susceptor 4. It is designed to be larger toward the inner periphery. The susceptor 4 is configured to be rotatable by the drive motor 9 via the drive shaft 6.

The susceptor 4 is heated by infrared lamps 5a and 5b provided between the flow path forming body 20 and the reaction vessel 1. In order to keep the surface temperature of the susceptor 4 uniform, the infrared lamps 5a and 5b
The zone can be controlled independently. Since the infrared lamps 5 a and 5 b are provided above the flow path forming body 20, quartz or the like that is transparent to infrared rays is used as the material of the flow path forming body 20. In the example of FIG. 1, the flow path forming body 20 has a hollow structure, and a gas inlet 12 and a gas outlet 13 for introducing and removing gas into and from the hollow are provided through the reaction vessel 1. By introducing a heating or cooling gas into the flow path forming body through the gas inlet 12 and discharging the gas through the outlet 13, the temperature of the susceptor can be more easily controlled. When it is not necessary to heat or cool the flow path forming body 20, it is not necessary to make it hollow, and it is a matter of course that the flow path forming body 20 may have a plate shape.

A gas inlet provided in the reaction vessel 1 so that the pressure difference between the space 60 between the susceptor 4 and the flow path forming body 20 and the space 70 between the reaction vessel 1 and the flow path forming body 20 is eliminated. A purge gas is supplied from an outlet 14 and a gas outlet 15
The pressure is controlled by a pressure gauge (not shown).

【Example】

Using a device shown in FIG. 1, a 0.5 μm high-resistance GaAs film is deposited on a GaAs substrate.
An active layer of GaAs doped with i is deposited to a thickness of 0.3 μm,
Further, a high-resistance GaAs film was deposited thereon at 0.1 μm, and a film thickness distribution and a carrier concentration distribution were obtained by CV measurement. As a result, the in-plane film thickness uniformity by the conventional method is ±
In contrast to 1.5%, the method was able to fall within ± 1.0%. Also, the substrate 1 on the same susceptor
The variation in the film thickness between the zero faces is ± 2.1 in the case of the conventional method.
% To ± 1.6%, and the variation in carrier concentration is ± 2.3% between 10 substrates in the conventional method.
% Was improved to ± 1.3% in the case of the present invention.

[0011]

As described above in detail, according to the present invention, after the source gas is introduced from the gas inlet provided on the back surface side of the susceptor on which the substrate is mounted, and once diffused radially on the back surface of the susceptor, The gas flows along the gas flow path forming body provided on the substrate mounting surface of the susceptor to the susceptor surface, and is evacuated to the outside of the reaction vessel from an exhaust port provided at the center of the susceptor. The flow of the above reaction gas could be made very uniform. As a result, the uniformity of the deposited film thickness in the plane of the substrate and the variation in the film thickness among a plurality of substrates were significantly improved. In addition to the heating device for the susceptor, a heating or cooling device is added to the flow path forming body itself, and the temperature distribution of the substrate mounting surface of the susceptor is controlled in the radial direction of the susceptor, so that the carrier concentration uniformity is improved. Could be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a vapor phase growth apparatus according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Gas outlet 3 Substrate 4 Susceptor 5, 5a, 5b Heater 6 Drive shaft 7, 12 Gas inlet 8 Gear 9 Drive motor 10, 13 Exhaust port 14 Page gas inlet 15 Page gas exhaust Outlet 16 Reaction vessel flange 20 Flow path forming body

Claims (2)

[Claims] 1. A reaction container, a susceptor provided in the reaction container for holding a substrate, a gas inlet provided in a central portion of the reaction container and supplying a raw material gas toward the central portion of the susceptor. In a vertical (pancake-type) reactor having an exhaust port for exhausting unnecessary gas in the reaction vessel, the gas inlet is provided on the back side of the susceptor and is introduced from the gas inlet. The raw material gas is once diffused radially on the back surface of the susceptor on which the substrate is mounted, then flows on the susceptor surface along the flow path forming body provided on the susceptor on the substrate mounting surface, and reacts from an exhaust port provided in the center of the susceptor. A vapor phase growth apparatus configured to exhaust gas to the outside of a container. 2. The vapor phase growth apparatus according to claim 1, wherein the flow path forming body has a structure that can be heated or cooled.