JPH01222438A - Vapor growth device - Google Patents

Abstract

PURPOSE:To relax a difference between a gas flow velocity at the central part of a reactor and a gas flow velocity in the vicinity of the inner wall of the reactor and to improve significantly the uniformity of the film thickness, which is formed within the surface of a substrate, of a grown thin film by a method wherein a shielding plate, whose from and sectional area are equal to the form and sectional area of a raw gas introducing vent, is provided. CONSTITUTION:The title device has a rectifying plate 10 provided with a plurality of fine holes and a shielding plate 11 for shielding the flow of raw gas introduced through a raw gas introducing vent 8 between the plate 10 and the vent 8. In the case a GaAs thin film is grown on a GaAs substrate 1, trimethyl gallium and arsin are introduced in a reactor 2 through the vent 8 after being diluted with hydrogen gas (carrier gas) 7, but the raw gas collides against the plate 11. After that, after passing through the fine holes of the plate 10, the raw gas 5 is fed to the heated substrate and the GaAs thin film 9 is formed by thermal decomposition. Thereby, it can be relaxed for a gas flow velocity at the central part of the reactor to be accelerated and the uniformity of the film thickness of an epitaxially grown layer can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vapor phase growth apparatus, and more particularly to a vertical vapor growth apparatus that improves the in-plane uniformity of an epitaxially grown layer.

[Conventional technology]

Conventionally, this type of vapor phase growth apparatus has a configuration as shown in FIG. The substrate 1 is placed on a susceptor 3 in a reactor 2 made of quartz, and is heated by induction heating the susceptor 3 using high frequency waves induced by a coil 4. The raw material gas 5 is flow-controlled by a mass flow controller (MFC) 6, diluted with a carrier gas 7, and introduced into the reactor 2 through a raw material gas inlet 8.

A thin film 9 is formed on the substrate 1 by thermal decomposition on the substrate 1 . In FIG. 3, 12 is a valve, 13 is a gas outlet, and 14 is a substrate rotation mechanism.

[Problem to be solved by the invention]

In the conventional vertical vapor phase growth apparatus described above, for example, trimethyl gallium (Ga(CHs)s:TMG) and arsine (
Ga Ar
When epitaxially growing the at thin film 9, the source gas 5 is diluted with hydrogen (H2) gas 7, introduced through the source gas inlet 8, and supplied to the GaAs substrate 1 heated to about 600°C. Reaction furnace 2 near where the substrate 1 is placed
Since the cross-sectional area of the substrate 1 is larger than that of the raw material gas inlet 8,
A distribution occurs in which the gas flow velocity in the vicinity is fast in the center and slow near the inner wall of the reactor 2. Because of that, G a A has grown
The thickness of the thin film 9 is thick near the center of the susceptor 3 and thinner at the periphery, as shown in FIG. was there. This non-uniformity in film thickness cannot be resolved even if the substrate is rotated by the substrate rotation mechanism 14.

[Means to solve the problem]

The vapor phase growth apparatus of the present invention includes a rectifying plate provided with pores inside the reactor, and a shielding plate whose cross-sectional area is equal to the shape and cross-sectional area of the raw gas inlet.

According to the present invention, it is possible to alleviate the difference in gas flow velocity between the central portion of the reactor and the vicinity of the inner wall.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention. In the figure, parts with the same numbers as in FIG. 3 are the same components as in FIG. 3.

The difference from the conventional vertical vapor phase growth apparatus is that a rectifying plate 10 with pores is provided inside the reactor between the raw material gas inlet 8 and the susceptor 3, and that the raw material gas inlet 8 and the rectifying plate 10 This point has a shielding plate 11 between them. The current plate 10 and the shielding plate 11 are made of quartz like the reactor 2, and the current plate 10 has pores with a diameter of 2 mm uniformly provided at intervals of 4 mm. Further, the shielding plate is arranged at a position to block the flow of the raw material gas.

When growing a GaAs thin film on a GaAs substrate 1, trimethylgallium and arsine are diluted with hydrogen gas 7 and then introduced into the reactor 2 from the source gas inlet 8, but the source gas is Collision with 11. After that, the raw material gas 5 passes through the pores of the rectifier plate 10, and then heated to approximately 600°C.
G is supplied to a GaAs substrate heated to
An a As thin film 9 is formed. In order to avoid the influence of the geometric shape of the pores of the rectifying plate 10, it is necessary to rotate the substrate 1 by the substrate rotation mechanism 14 at a rotation rate of 10 times or more per minute.

In addition, thermal decomposition of the raw material gas in the shielding plate 11 and the current plate 10 did not occur at all if the distance between the current plate 10 and the susceptor 3 was sufficiently large.

GaA was grown to a thickness of 3 μm using the vertical vapor phase growth apparatus of the present invention.
FIG. 2 shows the distribution of film thickness within the wafer surface when a thin film is grown. The increase in film thickness near the center of the substrate was suppressed, and the variation was ±3% with respect to the average value.

Note that if the cross-sectional area of the shielding plate 11 is made larger than the cross-sectional area of the source gas inlet 8, the film thickness at the center of the substrate becomes thinner, and if it is made smaller than the cross-sectional area of the source gas inlet, the film thickness at the center becomes thicker. In both cases, the uniformity tended to deteriorate. Therefore, the uniformity was the best when the cross-sectional area of the shielding plate 11 was equal to the cross-sectional area of the source gas inlet 8.

〔Effect of the invention〕

As explained above, in the present invention, by once blocking the flow of the raw material gas and then adjusting the flow of the raw material gas using the baffle plate 10, it is possible to alleviate the increase in the gas flow velocity in the central part of the reactor. Therefore, there is an effect that the uniformity of the thickness of the grown thin film within the substrate can be significantly improved.

Moreover, since the raw material gas is sufficiently mixed between the raw material gas inlet 8 and the rectifying plate 10, for example, A l x G & 1-XA
This has the effect of improving the uniformity of the composition ratio X when a mixed crystal such as S is grown, or the uniformity of the carrier concentration when doped.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a vertical vapor phase growth apparatus according to an embodiment of the present invention, and FIG. 2 is a GaAs thin film grown by the vertical vapor phase growth apparatus shown in FIG. 1, which is an embodiment of the present invention. Figure 3 is a cross-sectional view of a conventional vertical vapor phase growth apparatus.
Figure 4 shows G grown using a conventional vertical vapor phase growth apparatus.
FIG. 3 is an in-plane distribution diagram of the film thickness of the a As thin film. l...Substrate (GaAs substrate), 2...
Reactor, 3... Susceptor, 4... Coil, 5... Raw material gas, 6... Mass flow controller, 7... Carrier gas, 8...・・・
... Raw material gas inlet, 9... Thin film, 10...
... Rectifying plate, 11... Shielding plate, 12...
... Valve, 13... Gas discharge port, 14...
...Substrate rotation mechanism. Agent Patent Attorney Susumu Uchihara Figure 1 board piece! Figure 2

Claims (1)

[Claims] A rectifying plate provided with a plurality of pores and provided between a raw material gas inlet for introducing the raw material gas into the reactor and a susceptor on which the substrate is placed, and between the rectifying plate and the raw material gas inlet, A vapor phase growth apparatus comprising: a shielding plate provided to block the flow of the raw material gas introduced from the raw material gas inlet.