JPH04369213A - Vapor epitaxial growth apparatus - Google Patents

Abstract

PURPOSE:To obtain an epitaxial crystal whose composition and thickness are uniform on all regions of a substrate. CONSTITUTION:In an apparatus, a plurality of kinds of raw-material gases, for epitaxial growth use, whose component is different from each other are introduced into a reaction tube 5, the plurality of raw-material gases are heated and decomposed on a substrate 7, for epitaxial growth use, which has been placed on a substrate-heating stand 6 installed inside the reaction tube, and a compound semiconductor crystal is epitaxially grown on the substrate 7. The apparatus is constituted in the following manner: a gas passage 11 where a gas-exit end part 14 in which the plurality of raw-material gases flow up to a part near the substrate 7 in a separated manner without being mixed with each other and from which the raw-material gases flow out is situated so as to be brought close to the surface of the substrate 7 is installed inside the reaction tube 5; a plurality of gas-flow control plates 17 which change the gas-flow direction of the raw-material gases are installed in the gas-exit end part 14 in the gas passage 11; and the raw-material gases flow between the gas-flow control plates 17.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a vapor phase epitaxial growth apparatus,
) relates to an apparatus for vapor phase epitaxial growth of compound semiconductor crystals.

Mercury, cadmium, tellurium (Hg1-x C
When forming compound semiconductor crystals such as cadmium tellurium (dxTe), in order to obtain the crystals in a large area and in a thin layer state convenient for device formation, cadmium tellurium (
A compound semiconductor substrate such as CdTe is used as a substrate for epitaxial growth, and Hg1-x Cdx T, which is a sensing element forming material, is grown on it by vapor phase epitaxial growth.
Forms e-crystals.

0003

[Prior Art] Conventionally, such Hg1-x Cdx
As shown in FIG. 4, an apparatus for epitaxially growing a Te crystal is used, as shown in FIG. Hydrogen gas is introduced into the dimethyl cadmium [Cd(CH3)2] evaporator 2 which can accommodate dimethyl cadmium, and hydrogen gas is introduced into the diethyl tellurium evaporator 3 which can accommodate diethyl tellurium [Te(C2H5) 2]. A plurality of types of raw material gas for epitaxial growth consisting of hydrogen gas carrying diethyl tellurium are introduced into the reaction tube 5 through a plurality of gas introduction tubes 4.
is flowing inside.

[0004] Then, a carbon substrate heating table 6 installed in the reaction tube 5 is heated, and the CdTe placed on it is heated.
The epitaxial growth substrate 7 is heated, and the source gas for epitaxial growth that has flowed onto the substrate 7 is thermally decomposed to grow Hg1-x Cdx Te crystals on the substrate by vapor phase epitaxial growth.

[0005]

[Problems to be Solved by the Invention] However, the temperature of the hydrogen gas capable of carrying the above-mentioned Hg gas is heated to a temperature of about 200 °C in order to prevent mercury from solidifying and adhering to the gas introduction pipe. ing. On the other hand, dimethyl cadmium gas or hydrogen gas supporting diethyl tellurium gas is at room temperature, so if these raw material gases for epitaxial growth at different temperatures are mixed in the gas introduction tube 8 before flowing into the reaction tube 5. may react with each other and decompose.

[0006] Therefore, when these raw material gases reach the epitaxial growth substrate 7, the proportion of these raw material gases supported in the hydrogen gas is determined by the amount of gas from each of the evaporators 1, 2, and The composition may be different from the composition of the source gas immediately after being introduced into the introduction tube 4, and there is a problem that an epitaxial crystal of Hg1-x Cdx Te with a desired composition cannot be obtained.

Further, the substrate heating table 6 is heated for epitaxial growth, and therefore the entire inside of the reaction tube is heated. Therefore, the raw material gas for epitaxial growth introduced into the reaction tube 5 is heated to the substrate 7 for epitaxial growth.
There is a risk that the raw material gases of the desired composition will not reach the surface of the substrate 7 because they may react with each other and decompose within the reaction tube 5 before the source gases reach the surface of the substrate 7 .

Therefore, there is a problem that epitaxial crystals having a predetermined thickness and composition cannot be formed with good reproducibility. The present invention aims to eliminate the above-mentioned drawbacks and provide an apparatus in which source gases are not mixed with each other until they reach a substrate for epitaxial growth, but are mixed very close to the substrate.

[0009]

[Means for Solving the Problems] The vapor phase epitaxial growth apparatus of the present invention introduces a plurality of types of raw material gases for epitaxial growth having different components into a reaction tube, and performs the above-mentioned epitaxial growth on a substrate for epitaxial growth placed in the reaction tube. In an apparatus for epitaxially growing a compound semiconductor crystal on a substrate by thermally decomposing a plurality of raw material gases, the plurality of raw material gases flow separately to the vicinity of the substrate without mixing with each other, and A gas passage is provided in the reaction tube such that an outlet end of the gas flowing out is close to the surface of the substrate, and the direction of the gas flow of the raw material gas is changed to the gas outlet end from which the gas of the gas passage flows out. The present invention is characterized in that a plurality of gas flow control plates are provided, and the raw material gas is made to flow between the gas flow control plates.

[0010] Also, the gas flow control plate is penetrated by a support shaft installed at the gas outlet end through which the gas flows out, and the angle of the surface of the gas flow control plate with respect to the support shaft can be adjusted. It is characterized by

[0011]

[Function] The apparatus of the present invention provides a number of raw material gas passages that are separated so that multiple types of raw material gases for epitaxial growth do not mix with each other, the number of which corresponds to the types of raw material gases for epitaxial growth. The gas outlet end of the substrate is positioned close to the surface of the substrate for epitaxial growth. In this way, raw material gases for epitaxial growth with different temperatures or compositions are introduced very close to the substrate without reacting with each other, and therefore epitaxial crystals of the desired composition can be formed on the substrate with good reproducibility. be able to grow.

[0012] A support shaft is provided at the gas outlet end,
A gas flow control plate made of a quartz plate is inserted at a predetermined interval along a plane perpendicular to the support shaft or oblique to the perpendicular direction of the support shaft. It is fixedly attached to the support shaft or movably relative to the support shaft.

[0013] By adjusting the angle that the surface of this gas flow control plate forms with the support axis, it is possible to supply the largest amount of source gas to the region on the epitaxial growth substrate where the crystal growth rate is slowest. Therefore, an epitaxial crystal having a uniform thickness can be grown over the entire region on the epitaxial growth substrate.

[0014]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. 1(a) and 1(b) are explanatory diagrams of the first embodiment of the present invention, and FIG. 1(b) is the A of FIG. 1(a).
-A' line sectional view.

As shown in FIGS. 1(a) and 1(b), the vapor phase epitaxial growth apparatus of the present invention is compatible with multiple types of epitaxial growth raw material gases such as mercury, dimethyl cadmium, and diethyl tellurium gas. A partition plate 15 in which gas passages 11 corresponding to the number of gas passages 11 are provided in the reaction tube 5
to form. The reaction tube 5 is composed of a reaction tube main body 5A, and a chip-shaped growth section reaction tube 12 having a structure that can be installed or removed in close contact with the reaction tube main body 5A so as to be able to rub against the reaction tube main body 5A.

In order to make the raw material gas passing through the gas passage 11 of the reaction tube main body 5A of the reaction tube 5 most efficiently hit the epitaxial growth substrate 7 in the chip-shaped growth section reaction tube 12, A bent quartz plate 13 is provided. In this growth section reaction tube 12, the gas outlet end 14 of the source gas gas passage 11, which is made of a bent quartz plate 13, is located very close to the epitaxial growth substrate 7. By preventing the raw material gases from mixing with each other before reaching the surface of the substrate 7, a chemical reaction is prevented.

The gas outlet end 1 of this gas passage 11
A rotatable carbon substrate heating table 6 is installed at a position opposite to the substrate heating table 4, and a CdTe epitaxial growth substrate 7 is placed on this substrate heating table 6.

Further, as shown in FIGS. 1(a) and 1(c), a quartz plate 13 formed by bending inside the chip-shaped growth section reaction tube 12 and a partition plate provided on the reaction tube main body 5A. 15
A support shaft 16 made of quartz is provided at the gas outlet end 14 between the support shaft 16 and a plurality of gas flow control plates 17 made of quartz plates are provided at a predetermined pitch on this support shaft 16. Allow raw material gas to flow through the gap. A gas flow control mechanism 18 is formed by combining the gas flow control plates 17 and the support shaft 16 at various angles θ. A large number of gas flow control mechanisms 18 are prepared.

This epitaxial growth substrate 7
The region of the growth section reaction tube 12 in which the growth section reaction tube 12 is installed is in the form of a chip that can be rubbed against the reaction tube main body 5A and can be replaced. Observe the fluctuation state seen from the moving direction, and select an appropriate gas flow control mechanism 18 having a gas flow control plate 17 whose angle θ with the support shaft 16 has a predetermined value according to the observed value. By installing the support shaft 16 at the gas outlet end 14 of the gas passage, the raw material gas can be concentrated and flowed to the region of the epitaxial growth substrate where the growth rate of the epitaxial layer is slowest.

In another embodiment, as shown in FIG. 2, instead of the gas passage described above, a substrate 7 for epitaxial growth is placed on a substrate heating table 6 provided in the reaction tube 12 of the growth section.
A structure may be adopted in which a plurality of source gas inlet pipes 22 having gas outlet ends 14 facing each other are provided.

As another embodiment, as shown in FIG. 3, a gas outlet end 14 of the raw material gas introduction tube 22 extends into the growth section reaction tube 12 from the outside of the growth section reaction tube 12 where the gas outlet ends 14 are gathered. The stainless steel wire 21 is attached to the gas flow control plate 17 which is rotatable with respect to the support shaft 16, and the stainless steel wire 2
1 is pulled out in an airtight structure to prevent gas leakage to the outside of the growth section reaction tube 12, and this stainless steel wire 2
A structure may be adopted in which the angle of the gas flow control plate 17 with respect to the support shaft 16 is adjusted by pulling the gas flow control plate 1 in an oblique direction. In this case, as shown in FIG. 1(c), the angle θ of the gas flow control plate 17 with respect to the support shaft 16 can be changed during the epitaxial growth process, thereby controlling the raw material gas flow for epitaxial growth. It becomes possible to uniformly apply it to the surface of a substrate for epitaxial growth.

[0022]

As described above, according to the vapor phase epitaxial growth apparatus of the present invention, multiple types of raw material gases for epitaxial growth at different temperatures are supplied directly above the substrate for epitaxial growth without mixing. This has the effect of obtaining stable epitaxial crystals.

Further, by providing the gas flow control plate, a gas flow is supplied to provide a uniform thickness on the substrate, so that there is an effect that an epitaxial crystal can be obtained with a uniform thickness on the substrate.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the device of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the device of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the device of the present invention.

FIG. 4 is an explanatory diagram of a conventional device.

[Explanation of symbols]

5 Reaction tube 5A Reaction tube body 6　Substrate heating table 7 Substrate for epitaxial growth 11 Gas passage 12 Growth section reaction tube 13 Quartz plate 14 Gas outlet end 15 Partition plate 16 Support shaft 17 Gas flow control board 18 Gas flow control mechanism 21 Stainless steel wire 22 Raw material gas introduction pipe

Claims (3)

[Claims] [Claim 1] A plurality of types of raw material gases for epitaxial growth having mutually different components are introduced into a reaction tube (5), and a substrate heating table (6) for epitaxial growth is placed on a substrate heating table (6) provided in the reaction tube (5). In an apparatus for thermally decomposing the plurality of raw material gases on the substrate (7) and epitaxially growing a compound semiconductor crystal on the substrate (7), the plurality of raw material gases are mixed with each other up to the vicinity of the substrate (7). A gas passage (11) is provided in the reaction tube (5) such that the gas outlet end (14) through which the raw material gas flows is close to the surface of the substrate (7). A plurality of gas flow control plates (17) are provided at the gas outlet end (14) of the gas passage (11) to vary the direction of the gas flow of the source gas, and a plurality of gas flow control plates (17) are provided between the gas flow control plates (17). A vapor phase epitaxial growth apparatus characterized in that the source gas flows through the vapor phase epitaxial growth apparatus. [Claim 2] The gas flow control plate (17) according to Claim 1.
is a support shaft (16) installed at the gas outlet end (14).
A vapor phase epitaxial growth apparatus characterized in that the angle of the surface of the gas flow control plate (17) with respect to the support shaft (16) can be adjusted. 3. The reaction tube (5) in the region where the substrate heating table (6) according to claim 1 is installed is connected to the reaction tube body (5).
A vapor phase epitaxial growth apparatus characterized in that it can be rubbed against A) and is detachably installed.