JPS6266621A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To suppress turbulent flow produced by collision of raw gas to the inner wall of a reactor by feeding nonreaction gas which does not relate to vapor-phase growing reaction between a substrate heating base and the inner wall of the reactor. CONSTITUTION:Raw gas is supplied from a raw material supplying gas tube 2 of a reactor 1 to arrive at a substrate 3. Nonreaction gas is supplied from a gas guide tube 7, and fed between a substrate heating base 3 and the inner wall of the reactor 1. Reaction gas flow which tends to collide with the inner wall of the reactor 1 becomes like a gas flow 9 by nonreaction gas flow 8 to holder the laminar flow state of the reaction gas flow on the substrate 1. According to this vapor-phase growing apparatus, since a turbulent flow produced by the influence of heating the substrate can be suppressed to hold the raw gas flow on the substrate in a laminar flow state, a crystal of high quality can be obtained uniformly over a large area.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vapor phase growth apparatus for forming a high quality and uniform semiconductor crystal growth film.

BACKGROUND OF THE INVENTION In recent years, in the field of semiconductor devices, research and development of elements with complex structures has been actively conducted.

In response to this current situation, vapor phase growth is attracting attention because it allows for precise control of extremely thin growth layers and uniform growth over a large area. In particular, the MOCVD method is an organometallic thermal decomposition method using an organometallic material, in which the substrate is heated to the growth temperature.
A crystalline thin film is grown epitaxially by thermally decomposing raw material gases such as organic metals and hydrides on the surface of a substrate.

Conventionally, vapor phase growth reactors include horizontal and vertical reactors.

FIGS. 4 and 6 show schematic cross-sections of the vicinity of horizontal and vertical reaction tubes of a conventional MOCVD vapor phase growth apparatus. A raw material gas is supplied from the raw material supply gas pipe 2 of the reaction tube 1, and the substrate 3 is
Let the raw material gas reach. 4 indicates the raw material gas flow. The raw material gas is thermally decomposed on the substrate 3 by the heat of the substrate heating table S, so that a crystal thin film is epitaxially grown on the substrate 3. The residual gas is exhausted from the exhaust pipe e. Growth depends on the flow rate of source gas and substrate temperature, but for example, GaA
When growing g, TMG (trimethyl gallium) =
10 CC/min, AsHa (arsine) = 16
CC/m1n9H2 gas = 217min, substrate temperature = 78δ°C, good GaAg on GaAs substrate
An epitaxial thin film is formed.

GaAs-based devices include A11-xG following GaAs.
a.

Although As (0≦X≦1) may also grow,4 for example, the growth conditions for A10.3Ga0.7As are TMG=10
αshi'min.

TMA()rimethylaluminum)=10αshi'm i
n.

AsH3=15αmin, H2 gas=21
/min, substrate temperature = 78o''C.

Problems to be Solved by the Invention In general, the quality of a grown crystal is closely related to the flow conditions of the raw material gas during growth. In other words, unless the source gas flow is in a uniform laminar flow state, a uniform, high-quality crystalline thin film cannot be epitaxially grown over a large area. However, in the above method, the raw material gas flow collides with the inner wall due to the influence of thermal convection, generating a vortex, as in the raw material gas flow 4 shown in FIGS. 4 and 6. This eddy flow disturbed the raw material gas flow near the substrate, making it impossible to maintain a uniform laminar flow state. Furthermore, if the flow velocity of the raw material gas is increased so that the raw material gas flow is not affected by thermal convection, the collision of the raw material gas against the substrate heating stage becomes more intense, and turbulence is increasingly generated on the substrate. The present invention solves this problem and creates a laminar flow state.

Means for Solving the Problems The technical means of the present invention for solving the above problems is a vapor phase growth apparatus for vapor phase growth on a semiconductor substrate, in which a source gas is introduced into a reaction tube in which the substrate is placed. A first gas introduction pipe is provided for the reaction, and a second gas introduction pipe is provided for flowing a non-reactive gas not involved in the vapor phase growth reaction between the substrate heating table and the inner wall of the reaction tube. This is what I did.

For production The effects of this technical means are as follows.

When a non-reactive gas that does not participate in the vapor growth reaction is passed between the substrate heating table and the inner wall of the reaction tube, the raw material gas that is about to collide with the inner wall of the reaction tube due to the influence of thermal convection is caused by the non-reactive gas flow to cause the substrate heating table to flow. Since it is pushed farther downstream in the gas flow, it is possible to suppress the turbulent flow caused by collision with the inner wall, thereby solving the problem that the turbulent flow disturbs the laminar flow state of the source gas on the substrate.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3. In FIGS. 1 to 3, the same components as those in FIGS. 4 and 6 are given the same numbers, and detailed explanations will be omitted. A substrate 3 is placed on a substrate heating table 6. Substrate heating methods include high-frequency heating, infrared heating, resistance heating, and the like, but in this embodiment, high-frequency heating, which has a fast temperature increase rate, is used.

Now, explanation will be given by taking as an example the crystal growth of Engineering n1-E Ga Engineering As yPl-A.

The growth conditions depend considerably on the equipment, but for example, the substrate temperature is 670°C, the TEI (ethyl indium) flow rate (36°C) = 350 CCv/min, and the TEG
(Triethylgallium) H2 flow rate (0″C) = 80
cc/min, AsH3= 100CC/m
i n , PH3=170/min, total flow rate of H2 flowing through the reaction gas introduction pipe 4 61/min,
Matched to InP under reduced pressure of 150 Torr (1Δa/
al<lX10) In1-, GaxAsyPl.

(X~0.27, y-0,67) A quaternary mixed crystal is obtained. On the other hand, hydrogen gas was used as the non-reactive gas, and the flow rate was 10
The gas is supplied from the gas introduction pipe 7 at a rate of 1/min. The reactant gas flow that is about to collide with the inner wall is pushed downstream by the non-reactant gas flow 8, so the reactant gas flow becomes as shown in 9 in the figure, and the reactant gas flow is in a laminar flow state on the substrate 1. is maintained.

In this way, I n 1-xGa xAs yP 1.
,, the growth of y (xria 27 *y-0,57) is 3
Even after 5 runs, the in-plane variations in composition and film thickness were extremely small. Composition and film thickness (growth time: 1H)
) within the plane (for each radius, x = 0.27±
0.02, y=0.57±0.02 and 1μm±0
．． 02, a quaternary mixed crystal with extremely uniform surface morphology and good surface morphology was obtained with good reproducibility.

FIG. 2 is a schematic configuration diagram showing a metal organic vapor phase growth apparatus having a reaction tube 1 having the above structure.
Adjust the flow rate with
Raw material gas is supplied to the reaction tube 1 from the organic metal bubbler 2 and the organometallic bubbler 23. A carrier gas for forming the non-reactive gas and one source gas is supplied from a high-pressure cylinder 27 of hydrogen gas. The substrate heating table 5 is heated using the high frequency power source 25 and the high frequency coil 24, and growth is performed while maintaining the temperature of the substrate 3 at the growth temperature.

Note that the non-reactive gas introduction pipe 7 needs to be optimized depending on the shape of the substrate heating table 2. For example, as shown in FIG. 1, when the substrate 3 is placed obliquely with respect to the raw material gas flow on the upstream side of the substrate heating table 6, the inner wall of the substrate 3 is placed between the surface of the substrate 3 and the inner wall of the reaction tube 1. Figure 1 (1G
A non-reactive gas introduction pipe 7 having a flat and horizontally long opening as shown in the front view is used. In addition, when the substrate 3 is placed perpendicularly to the above raw material gas flow, for example, a non-reactive gas introduction pipe having a flat horizontally long opening as shown in the top view of FIG. 7 is used.

In the above explanation, a metal organic vapor phase growth apparatus has been described, but the present invention can also be applied to a normal vapor phase growth apparatus. Further, although the non-reactive gas and the carrier gas are shown to be the same, the present invention is not limited to this, and a different gas such as nitrogen, etc., which does not participate in the crystal growth reaction may be used.

Effects of the Invention As described above, according to the present invention, it is possible to suppress turbulence caused by the influence of substrate heating, which was one of the problems in vapor phase growth equipment, and to improve the flow of raw material gas on the substrate. Since it is possible to maintain a laminar flow state, uniform and high quality crystals can be obtained over a large area.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a reaction tube section of a vapor phase growth apparatus according to an embodiment of the present invention, FIG. 2 is a gas system diagram of the vapor phase growth apparatus of this embodiment, and FIG. 3 is a diagram showing another embodiment of the present invention. 4 and 5 are cross-sectional views of the reaction tube section of the conventional vapor phase growth apparatus. 1... Reaction tube, 2... Raw material gas introduction tube, 3... Substrate, 6... Substrate heating table, 6
. . . Exhaust pipe, 7 . . . Non-reactive gas introduction pipe, 8 . . . Non-reactive gas flow. Name of agent: Patent attorney Toshio Nakao and 1 other person
3 Figure 3-Act Autumn 4-1λDe charge Busushi 1 (-C-Heiki 1 Figure 5

Claims (5)

[Claims] (1) A vapor phase growth apparatus for vapor phase growing a thin film on a semiconductor substrate, which includes a reaction tube in which the substrate is placed, and a first gas introduction tube that supplies source gas onto one main surface of the substrate. A vapor phase growth apparatus comprising a second gas introduction pipe for flowing a non-reactive gas that does not participate in the vapor growth reaction between a substrate heating table that heats the substrate and an inner wall of the reaction tube. (2) The reaction tube is horizontal, and the end of the second gas introduction tube is disposed upstream of the substrate heating table in the gas flow and near the inner wall above the substrate heating table. Vapor phase growth apparatus described in Section 1. (3) The reaction tube is vertical, and a plurality of second gas introduction tubes are arranged near the inner wall of the reaction tube on the upstream side of the gas flow from the substrate heating table. Vapor phase growth apparatus described in Section 1. (4) The vapor phase growth apparatus according to claim 1, wherein the raw material gas for crystal growth is a raw material gas containing an organic metal. (5) The vapor phase growth apparatus according to claim 1, wherein the non-reactive gas is hydrogen, nitrogen, or a rare gas.