JPH02235348A - Vapor epitaxial growth equipment - Google Patents

Abstract

PURPOSE:To obtain an epitaxial layer whose composition and film thickness are stable by a method wherein two or more kinds of gas for epitaxial growth is supplied on a substrate so as not to mix with one another, and the substrate is arranged so as to be inclined to the gas flow direction enabled to rotate. CONSTITUTION:Into the upper side of a reaction vessel 1 separated by a separating plate 11, the following are introduced: hydrogen gas as carrier gas, and dimethyl cadmium gas and diethyl tellurium gas carried by hydrogen gas. Into the lower side of the separating plate 11, the following are introduced: hydrogen gas as carrier gas, and mercury gas and diethyl tellurium gas carried by hydrogen gas. A substrate 2 is heated at 410 deg.C as the temperature of a susceptor 3 on which the substrate 2 is mounted. These gases are carried On the substrate 2 without reacting to one another; CdTe crystal formed on the upper side of the substrate 2 surface, and HgTe crystal formed on the lower side are mutually diffused by the rotation of the substrate 2, thereby obtaining an epitaxial layer of Hg1-xCdxTe.

Description

[Detailed Description of the Invention] [Summary] Regarding a vapor phase epitaxial growth apparatus, the purpose is to provide an apparatus for obtaining an epitaxial layer with a uniform composition. An apparatus for growing an epitaxial layer on a substrate by thermally decomposing a plurality of types of epitaxial growth gases introduced into the substrate, wherein the plurality of types of epitaxial growth gases do not mix with each other immediately before reaching the epitaxial growth substrate. In addition to providing such gas mixing prevention means, the substrate is installed obliquely and rotatably so as to be exposed to the plurality of gas flows.

r Industrial application field] The present invention relates to a vapor phase epitaxial growth apparatus.

Mercury, cadmium, tellurium (Hg?-xC) with a narrow energy band gap can be used as materials for forming infrared sensing elements.
d. A compound semiconductor crystal made of Te) is used.

When epitaxially growing such a crystal of Rg+-x Cdx Te, a susceptor with an epitaxial growth substrate such as cadmium telluride (CdTe) is installed in a reaction tube, and mercury (}Ig) and dimethyl cadmium ( Epitaxial growth gases with different decomposition temperatures, such as Cd(Cllz)z) and diethyltellurium [Te(C!■s)■], are introduced into the reaction tube together with hydrogen gas as a carrier gas, and the septa on which the substrate is placed are heated. By heating, the epitaxial growth gas introduced into the reaction tube is decomposed, and ug-x Cd. Te
crystals are grown epitaxially.

This method is called MOCVD (Metal
Organic Chemical Vapor De
position; organometallic chemical vapor deposition method). [Prior art] Regarding the conventional epitaxial growth apparatus, the seventh
This will be explained using figures.

As shown in the figure, a susceptor 3 made of graphite on which an epitaxial growth substrate 2 made of CdTe is mounted is installed in a reaction vessel 1, and a mercury evaporator is supplied with hydrogen gas as a carrier gas from a gas inlet 4 of the reaction vessel 1. 5, the mercury gas is carried on the carrier gas, the dimethyl cadmium gas is passed through the dimethyl cadmium evaporator 6, and the dimethyl cadmium gas is carried on the carrier gas, and the dimethyl cadmium gas is passed through the diethyl tellurium evaporator 7, and is carried on the carrier gas. An epitaxial growth gas consisting of diethyl tellurium gas is introduced into the reaction vessel 1. Then, high-frequency power is applied to the high-frequency induction coil 8 provided around the reaction vessel 1 to heat the susceptor 3 and the substrate 2 thereon.
The epitaxial growth gas introduced into the substrate is thermally decomposed on the substrate to form an epitaxial layer of Hg+-xCdxTe on the substrate. [Problems to be Solved by the Invention] When a crystal of Hg+-, 1 cct Dimethyl cadmium decomposes into Cd
The decomposition temperature at which atoms are formed is approximately 260°C, and the decomposition temperature at which diethyl tellurium decomposes to form Te atoms is approximately 380°C. The temperature is maintained at approximately 400°C, close to the decomposition temperature.

By the way, in order to heat the substrate 2 to the above-mentioned 400°C, the susceptor 3 is heated to a temperature of 400°C or higher, and by heating the susceptor 3, the temperature inside the reaction vessel 1 on the gas introduction side of the susceptor increases. Due to this temperature rise in the reaction vessel, dimethyl cadmium gas, which has a low decomposition temperature, may be decomposed before reaching the substrate 2.

The decomposed Cd atoms react with Hg atoms introduced into the reaction vessel in the form of a single element, and cadmium amalgam is produced before the mercury gas and dimethyl cadmium gas reach the substrate. Then, the epitaxial growth gas in which the Hg atoms in the Hg gas or the Cd atoms in the dimethyl cadmium gas as the epitaxial growth gas are partially consumed reaches the substrate, and when such epitaxial growth gas is used, When epitaxially grown, Hj1-,lCdXTe of a predetermined composition
There is a problem that it is not possible to obtain an epitaxial layer.

The present invention solves the above-mentioned problems and aims to provide a vapor phase epitaxial growth apparatus in which epitaxial growth gases are prevented from mixing and reacting with each other before reaching a substrate.

[Means to solve the problem]

The vapor phase epitaxial growth apparatus of the present invention that achieves the above object has a gas mixture that prevents the plurality of epitaxial growth gases from mixing with each other immediately before reaching the epitaxial growth substrate 2, as shown in the principle diagram of FIG. It is characterized in that 1,000 stages of prevention l1 are provided, and in the region where the plurality of gases are mixed, the substrate 2 is installed obliquely and rotatably so as to be exposed to the plurality of gas flows.

[For production]

In the vapor phase epitaxial growth apparatus of the present invention, the cross-section of the reaction vessel is arranged in a direction from the gas inlet of the reaction vessel to the vicinity of the substrate in accordance with the type of epitaxial growth gas introduced into the reaction vessel. To achieve this, partition plates are provided to provide separate gas passages, and multiple types of gases with different components are separately introduced into each gas passage until these gases reach the substrate. By mixing the components with each other to prevent them from reacting, an epitaxial growth gas in which predetermined components are mixed at a predetermined concentration is supplied onto the substrate. Then, by placing the substrate in an oblique direction so that it is exposed to the gas flow of these multiple types of epitaxial growth gases and rotating the substrate, crystals are formed in a predetermined area of the substrate with a minute thickness using these supplied gases. They interdiffuse with each other, resulting in an epitaxial layer with a stable composition.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a front view of the first embodiment of the vapor phase epitaxial growth apparatus of the present invention, and FIG. 3 is a side view of FIG. 2.

In the vapor phase epitaxial growth apparatus of the first embodiment, a partition plate 11 made of quartz is provided on the cross section of the reaction tube container 1 along the direction of gas movement shown by arrow A. This partition plate 11 is provided from the gas inlet 12 of the reaction vessel l to the vicinity of the epitaxial growth substrate 2, and the disk-shaped susceptor 3 on which the epitaxial growth substrate 2 is placed is arranged from the horizontal direction when viewed from the front. It is installed so as to be tilted toward the front, tilted at a predetermined angle with respect to the direction of gas movement shown by arrow A, and made rotatable.

Hydrogen gas as a carrier gas, dimethyl cadmium gas supported by the hydrogen gas, and diethyl tellurium gas were introduced into the upper side of the reaction vessel 1 partitioned by the partition plate 11, which was partitioned by the partition plate 11. Hydrogen gas as a carrier gas, mercury gas supported by hydrogen gas, and diethyl tellurium gas are introduced into the lower part of the reaction vessel 1.

Then, the susceptor 3 on which the substrate 2 is placed is heated to a temperature of 410°C. Then, the decomposition temperature of dimethyl cadmium is about 260°C, and the decomposition temperature of diethyl tellurium is about 380°C, and the diethyl tellurium flowing into the gas passage 13A at the top of the partition plate 11 is hardly decomposed until it reaches the substrate 2. Therefore, if dimethyl cadmium decomposes and Cd
Even if atoms are generated, diethyl tellurium has not decomposed, so they will not react with the Te atoms of diethyl tellurium, and the dimethyl cadmium gas and diethyl tellurium gas flowing into the gas passage 13A on the upper side of the partition plate 11 will not interact with each other. It is transported onto the substrate without any reaction.

Further, the mercury and diethyl tellurium gas flowing through the gas passage 13B on the lower side of the partition plate 11 do not decompose because the temperature inside the reaction tube is below 380°C until the diethyl tellurium gas reaches the substrate. The gases do not react with each other and are transported onto the substrate. In this way, CdTe crystals are formed on the upper side of the surface of the epitaxial growth substrate 2 by the decomposed gas of dimethyl cadmium and diethyl tellurium, which are the epitaxial growth gases on the upper side of the partition plate 11. Further, IlgTe crystals are formed on the lower side of the surface of the substrate 2 by the decomposition gas of diethyl tellurium, which is the epitaxial growth gas on the lower side of the partition plate 11, and mercury. Then, when the substrate is rotated at a rotation speed faster than the crystal growth rate at which these crystals are formed to a minute thickness, for example, the formed CdTe and HgTe interdiffuse and form }Igl-. t
Cd. An epitaxial layer of To is obtained. Further, as shown in FIG. 4 to FIG. 6 as another example of this embodiment, gas inlet ports 21A, 21B having different heights from the bottom 1^ of the reaction vessel 1, and gas inlet ports 21A, 21B, 2
Gas outlet 22A corresponding to 1B. A plurality of gas inlet ports 22B are provided, and each gas inlet port 21A, 21B and gas outlet port 2 are connected to each other.
Gas passages 13A and 13B formed by 2A and 22B
A separate epitaxial growth gas is flowed through each. The state of gas flow in such a reaction vessel is
As shown in the figure. Gas passage 13A. 13B. The flows of the plurality of epitaxial growth gases flowing through the reactor 1 are made to intersect three-dimensionally in the vicinity of the area where the substrate 2 is placed inside the reaction vessel 1. The substrate 2 is tilted at a predetermined angle with respect to each gas flow so as to contact each of a plurality of different epitaxial growth gases in a region where the epitaxial growth gases intersect. In such a device, diethyl tellurium gas supported by hydrogen gas and dimethyl cadmium gas are flowed from the gas inlet 21B to the gas passage 13B, and then the gas inlet 21B is passed through the gas inlet 21B.
Even if mercury supported by hydrogen gas and dimethyl tellurium gas are introduced into the gas passage 13A, the same effect as in the first embodiment can be obtained. Further, in this embodiment, as shown in FIG. 4, the gas passage l3^
Although the gas passage 13A and the gas passage 13B are not orthogonal to each other, they are intersected at a predetermined angle with θ being a predetermined angle. It's okay.

In addition, in the first embodiment, two partition plates may be provided to allow the gas flow to flow in a three-layer structure, or in the second embodiment, the gas flow may be made into a three-layer structure. A method may be adopted in which the gas flows intersect with each other in the vicinity of the installation area of the substrate.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, multiple types of epitaxial growth gases reach the substrate in a state where they are not mixed with each other, so epitaxial growth gases with predetermined components are supplied onto the substrate. This has the effect of obtaining an epitaxial layer with a stable thickness. Fig. 5 is a cross-sectional view taken along the line TV-IV'' in Fig. 4, Fig. 6 is a schematic diagram showing the gas flow in the second embodiment, and Fig. 7 is an explanation of a conventional vapor phase epitaxial growth apparatus. It is a diagram.

In the figure, l is a reaction vessel, 1A is the bottom of the reaction vessel, 2 is an epitaxial growth substrate, 3 is a susceptor, l1 is a partition plate, 12
．． 21A and 21B are gas inlet ports, 13A and 13B are gas passages, and 22A and 22B are gas outlet ports.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of the device of the present invention, Fig. 2 is a front view of the first embodiment of the device of the present invention, Fig. 3 is a side view of Fig. 2, and Fig. 4 is a diagram of the device of the present invention. Plan view of 2nd embodiment, present invention g7
A certain one from III! Rimon diagram JseW pX'It, 822 Sakifgo,. slhfl
J Fig. 4 i4rfJr W- W'*+=3&- n#1fbm
GS
1m

Claims (3)

[Claims] (1) The susceptor (3) on which the epitaxial growth substrate (2) is installed is installed in the reaction vessel tube (1), and the plurality of epitaxial growth gases introduced into the reaction vessel are thermally decomposed and transferred onto the substrate. An apparatus for growing an epitaxial layer, comprising gas mixing prevention means (11) that prevents the plurality of epitaxial growth gases from mixing with each other immediately before reaching the epitaxial growth substrate (2), and 2) is installed obliquely and rotatably so as to be exposed to the plurality of gas flows. (2) A partition plate (11) that partitions the passage of multiple types of gases introduced into the reaction container (1) is installed to control the gas flow from the gas inlet (12) of the reaction container (1) to the vicinity of the substrate. The epitaxial growth substrate (2
2. The vapor phase epitaxial growth apparatus according to claim 1, wherein the susceptor (3) in which the susceptor (3) is installed is rotatably installed obliquely with respect to the plurality of gas flows. (3) A plurality of gas inlets (21A, 21B) at different heights from the bottom (1A) of the reaction vessel (1), and a gas outlet (22) corresponding to the gas inlets (21A, 21B).
A, 22B), and the gas inlet (21A, 21B) and the gas outlet (21A, 21B) are installed.
22A, 22B) formed by gas passages (13A, 13
B) The gas flows of the plurality of epitaxial growth gases passing through the substrate (2) are arranged to intersect with each other in the vicinity of the installation area of the substrate (2), and the susceptor on which the substrate (2) is installed is connected to the gas flow of the plurality of types of epitaxial growth gases. 2. The vapor phase epitaxial growth apparatus according to claim 1, wherein the vapor phase epitaxial growth apparatus is installed rotatably in an oblique direction with respect to the gas flow.