JPS61242012A - Vapor-phase growth device - Google Patents

Abstract

PURPOSE:To obtain the film of uniform thickness ranging over a wide area using a small-sized growing furnace by a method wherein a plurality of gas introducing portse are provided vertically crossing the direction of gas stream in a growth furnace in parallel with the surface of a substrate. CONSTITUTION:A substrate 11 is placed on the supporting stand 12 made of carbon. The crystal growth raw gas of the same constitution crosses a gas stream, and it is fed to a growth furnace 15 from the gas introducing pipes 14 having gas introducing ports 13 which are arranged in parallel with the surface of the substrate. When GaAs is going to be grown by performing an MOCVD, the hydrogen which is used as carrier gas is fed into the container 24 containing the triethyl gallium 23 which is kept warm in a constant temperature vessel 22 after the flow rate of said hydrogen is controlled by a mass-flow controller 21, and a bubbling is performed. Subsequently, the hydrogen gas containing triethyl gallium passed through the gas introducing pipe 14 and fed into the growth furnace 15 from the gas introducing ports 13. After a growth reaction is performed, the gas is exhausted to an exhaust system 29.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vapor phase growth apparatus capable of obtaining a semiconductor crystal growth layer having a uniform thickness over a wide range.

2. Description of the Related Art As an epitaxial growth technique for semiconductor crystals necessary for manufacturing semiconductor devices, there is a vapor phase growth method that utilizes thermal decomposition of raw material gas. For example, Monosif y (S IH4
), and metal organic chemical vapor deposition (MOCVD), which grows compound semiconductor crystals using organic metals (alkylated compounds). In these vapor phase growth apparatuses, the substrate is generally heated to a growth temperature, and the raw material gas is thermally decomposed on the substrate surface to grow crystals.

In the case of such vapor phase growth, the flow of raw material gas in the growth furnace greatly influences the crystal growth rate. Therefore, attempts have been made to obtain a uniform film thickness by devising various mechanisms for introducing the raw material gas. For example, as shown in Fig. 5, a uniform film thickness was obtained by making the horizontal width of the gas inlet for the source gas sufficiently wide relative to the width of the substrate (for example, in JP-A-58 -111313). That is,
A substrate 1 is placed on a support 2 in a growth furnace 6.

An introduction pipe 4 for introducing raw material gas into the furnace extends horizontally, and an exhaust pipe 41 is provided on the opposite side. The distal end of the gas introduction pipe 4 is formed as a wide part 42 that spreads in the horizontal direction. A raw material gas inlet 3 is arranged horizontally on the distal end surface of the wide portion, and its shape consists of one opening formed in the shape of a thin slit in the horizontal direction. For this reason,
The raw material gas coming out of the inlet 3 was uniformly diffused over the substrate surface, and a uniform film was formed.

Problems to be Solved by the Invention However, in a vapor phase growth apparatus having an inlet having such a shape, it is necessary to have a gas introduction pipe at the inlet that is sufficiently wider than the width of the substrate. The size also has to increase. This is because when gas flows inside a pipe, the flow rate of the gas decreases as it approaches the pipe wall.

Therefore, if the width of the gas inlet is about the same as the width of the substrate, the outflow speed of the gas at both ends of the gas inlet will be slower than in the center, so the raw material gas flowing on the substrate surface will also be slower at both ends of the substrate. . Therefore, the crystal growth rate at both ends of the substrate becomes slow and the film thickness becomes thin.

Means for Solving the Problems The technical means of the present invention for solving the above problems includes a plurality of gas inlets arranged perpendicularly to the gas flow direction of the growth furnace and parallel to the substrate surface; The present invention provides a vapor phase growth apparatus characterized in that raw material gas for crystal growth having the same configuration flows out from all of the gas inlets in the same direction and flows at a uniform flow velocity over the substrate surface.

For production The flow of gas in the tube is slow near the tube wall and fast in the center.

Therefore, the flow of gas exiting from one gas inlet is slow at the periphery of the inlet and faster at the center. However, by arranging multiple gas inlet ports in a horizontal line across the gas flow, the slow and fast gas flow areas alternate, so the overall flow of the introduced gas is smoothed out. It becomes uniform.

Therefore, the area where the flow rate of gas coming out of the gas inlet is constant is wider than in the case of the single thin slit gas inlet described above. For this reason, the width 1, where the flow rate of the gas flowing over the substrate surface is constant, is widened, so that the width in which a uniform film thickness can be obtained is widened.

Therefore, this means that if a plurality of inlets are arranged across the gas flow with the same width as the slit-shaped inlet described above, the width of the substrate can be made larger than before.
On the other hand, if the width of the substrate is the same, a growth furnace with a plurality of inlets arranged side by side will be smaller than a growth furnace with the aforementioned slit-shaped inlet.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4. As shown in FIG. 1, a substrate 11 is placed on a support base 12 made of carbon. Seven raw material gases for crystal growth having the same configuration are connected to the growth furnace 16 from a gas inlet pipe 14 in which respective gas inlets 13 are arranged so as to cross the gas flow perpendicularly and parallel to the substrate surface as shown in the figure. supplied to The diameter of each gas inlet 13 is 5 mm, the total width of the lined gas inlets 13 is 47 mm, and the inner diameter of the growth furnace 15 is 60 mm.
It is CI. In this example, a plurality of gas inlet ports were arranged adjacent to each other, but if crystal growth gas of the same configuration flows out from each inlet port, and the flow of the outflowing gas is similar, the shape of the gas inlet pipe may be changed. , the number, and the spacing of the gas inlets. For example, as shown in FIG.
A slit-shaped gas introduction pipe 4 having a structure in which the gas introduction pipe 3 is partitioned by a partition plate 61 may be used. GaAs was grown using an MOCVD apparatus having a growth furnace structured as shown in FIG. A schematic diagram of the gas system of this MOCVD apparatus is shown in FIG. When growing GaAa by the MOCVD method, triethylgallium (TEG(C2H5)3Ga), which is an alkylated product of Ga, was used as the raw material for Ga, and arsine (AsH3), which is a hydride, was used as the raw material for As. After controlling the flow rate of hydrogen (H2) as a carrier gas to 50' in by a mass flow controller 21, it is supplied to a container 24 containing triethyl gallium 23 kept at 3° C. in a constant temperature bath 22, and bubbling is performed. Thereafter, the hydrogen gas containing triethyl gallium passes through the gas introduction pipe 14 and is supplied to the growth furnace 5 from the gas introduction ports 3 lined up as shown in FIG. On the other hand, arsine was supplied to the growth furnace 15 through a gas introduction pipe 27 from a high-pressure cylinder 25 diluted with hydrogen, with the flow rate controlled to 200"/- by a mass flow controller 26.
1 is placed on a support base 2 made of carbon which is heated with high frequency by a high frequency coil 28, and the growth temperature is 700°C.

Therefore, the supplied source gas caused epitaxial growth of GaAs on the surface of the substrate 11 through a thermal decomposition reaction. The gas after the growth reaction is exhausted to the exhaust system 29.

The distribution of the growth rate of GaAs grown in this MOCVD apparatus in the lateral direction of the substrate is shown in FIG. 4(b). A portion with a uniform thickness of the grown layer was obtained with a width of 35111 mm.

Note that the total width of the arranged gas inlet ports is 47101 mm. For comparison, an attempt was made to grow GaAs using a conventional gas inlet pipe having a single slit-shaped gas inlet (width 47 mm). The distribution of the growth rate of GaAs+ in the lateral direction of the substrate in this case is shown in (a). The uniform thickness of the growth layer is 25
It was cod. Therefore, it can be seen that by arranging a plurality of gas inlets, a wider area of uniform film thickness can be obtained. In addition,
In this example, M.

Although the description has been made using a CVD apparatus, other vapor phase growth methods may be used as long as the vapor phase growth apparatus utilizes a thermal decomposition reaction of a source gas.

Effects of the Invention As described above, according to the present invention, it is possible to grow crystals with a uniform film thickness over a wide range in a relatively small growth furnace compared to conventional ones, and this invention will be extremely useful in vapor phase growth in the future. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a growth furnace section of a vapor phase growth apparatus according to an embodiment of the present invention, and FIG. 2 shows the structure of a gas introduction pipe of a vapor phase growth apparatus section according to another embodiment of the present invention. Perspective view shown, 3rd
The figure shows the gas system of a vapor phase growth apparatus according to an embodiment of the present invention, and FIG. A diagram to compare and explain the distribution of the substrate in the lateral direction,
FIG. 5 is a diagram showing the structure of a growth furnace of a conventional vapor phase growth apparatus. 11...Substrate, 13...Gas inlet,
15...Growth reactor. Name of agent: Patent attorney Toshio Nakao and one other person
Figure 4

Claims (3)

[Claims] (1) A plurality of gas inlet ports are arranged perpendicularly across the gas flow direction of the growth furnace and parallel to the surface of the substrate, and raw material gas for crystal growth of the same configuration is directed from all of the gas inlet ports in the same direction. A vapor phase growth apparatus characterized in that the flow flows out over the substrate surface at a substantially uniform velocity. (2) Vapor phase growth according to claim 1, characterized in that the plurality of gas introduction ports are provided with a slit-shaped gas introduction pipe having a structure partitioned by one or more partition plates. Device. (3) 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.