JPH01201926A - Vapor phase epitaxial growth - Google Patents

Abstract

PURPOSE:To obtain a superior epitaxial layer which does not produce composition variations and crystal defects, by forming prescribed temperature distribution regions along the direction vertical to the direction of a gas flow in a reaction tube after heating separately a susceptor and a heating member and introducing a gas for an epitaxial growth having a decomposition temperature which is extremely close to those of the above regions. CONSTITUTION:After installing a substrate 3 for epitaxial growth of CdTe on a susceptor 2, for example, air inside a reaction tube 1 is exhausted to produce a vacuum of 10<-5>Torr and then, the susceptor 2 is heated up to the temperature of 320 deg.C and a heating member 11 is heated up to 400 deg.C. The resultant temperature distribution regions of the diameter direction in the reaction tube 1 which holds a position between the susceptor 2 and the heating member 11 are: the region 31 which comes extremely close to the heating member 11 has the highest temperature; the region 32 which cones exceedingly close to the susceptor 2 has the lowest temperature; and the region 33 between regions 31 and 32 has an intermediate temperature between those of the regions 31 and 32. Thus, gases for an epitaxial growth are introduced into each temperature distribution region which comes extremely close to decomposition temperature of its gas through respective gas introducing tubes 21, 22, and 23 and the gases are decomposed with certainty.

Description

[Detailed Description of the Invention] [Summary] Regarding the vapor phase epitaxial growth method, a plurality of epitaxial growth gases having different decomposition temperatures introduced into a reaction tube are reliably decomposed on the substrate, and there is no compositional variation and no crystal defects. In order to obtain a good epitaxial layer, a susceptor for holding and heating the substrate is installed in a reaction tube, epitaxial growth gases having different decomposition temperatures are introduced into the reaction tube, and epitaxial growth is performed by heating the susceptor. In the method of decomposing a gas for use and attaching the decomposed components of the gas to a substrate, the susceptor is separated from the susceptor by a predetermined distance in a direction perpendicular to the direction of the gas flow in the reaction tube. a member is provided, and the susceptor and the heating member are heated separately to form a predetermined temperature distribution region in a direction perpendicular to the direction of gas flow in the reaction tube between the susceptor and the heating member, and the decomposition The epitaxial growth gases having different temperatures are separately introduced into a temperature distribution region in the reaction tube close to the decomposition temperature.

[Industrial application field]

The present invention relates to a vapor phase epitaxial growth apparatus, and in particular, even if multiple types of epitaxial growth gases with different decomposition temperatures are introduced into a reaction tube, they can be reliably decomposed on a substrate, and an epitaxial layer can be formed without compositional fluctuations or crystal defects. This invention relates to a vapor phase epitaxial growth method.

A compound semiconductor crystal of mercury, cadmium, and tellurium (fig + -xCd, Te) is used as the +A material of an infrared sensing element, and in order to obtain such a crystal in a thin layer state and over a large area, a vapor phase epitaxial growth method is used. or is used.

[Conventional technique +l;r] As shown in FIG. 2, in the conventional vapor phase epitaxial growth method, a susceptor 2 made of graphite is installed in a reaction tube 1 made of quartz, and cadmium for epitaxial growth is placed on the susceptor 2. A tellurium (CdTe) substrate 3 is installed. After the inside of the reaction tube 1 is evacuated to a predetermined degree of vacuum, mercury scum supported by hydrogen gas introduced from the gas introduction tube 4 and dimethyl cadmium ((
CI+3)2Cd) gas and diethyltellurium C(C2H5)zTe] gas supported by hydrogen gas are mixed in a gas mixer 5, and the mixed epitaxial growth gas is introduced into the reaction tube 1. Then, by applying high frequency power to the high frequency induction coil 6 provided around the reaction tube 1, the receptacle 2 is heated, and the substrate 3 is heated to a temperature of approximately 400°C. IIg+-x ca to decompose the gas for the substrate.

An epitaxial layer of T(!) is grown.

[Invention or problem to be solved]

By the way, among the epitaxial growth residues mentioned above, mercury is already a heavy element, and the decomposition temperature of dimethyl cadmilla is 260°C, and the decomposition temperature of diethyl tellurium is 380°C, which is suitable for the three types of epitaxial growth mentioned above. The most difficult to decompose of all gases.

Therefore, on a substrate with a constant heating temperature, mercury is already a single element, and then dimethyl cadmium and diethyl tellurium are easily decomposed in that order, so the degree of gas decomposition varies depending on each epitaxial growth gas, so it is difficult to achieve the desired composition. There is a problem that it is not possible to obtain an epitaxial layer.

In addition, insufficiently decomposed epitaxial growth gas components reach the substrate (=J), so the formed epitaxial layer cannot be obtained as a crystal with the desired composition, and crystal defects occur in the formed epitaxial layer, resulting in high quality. There is a problem that a suitable epitaxial layer cannot be obtained.

The present invention solves the above-mentioned problems, and even when the heating temperature of the substrate is kept constant, the epitaxial growth gas on the substrate can be reliably decomposed, and a high-quality epitaxial layer without compositional fluctuations or crystal defects can be obtained. The purpose of this project is to provide a vapor-phase Ettakinyal growth method J.

[Means for Solving the Problems] As shown in FIG. 1, the vapor phase epitaxial growth method of the present invention solves the above-mentioned problems. A zero force heating member 11 is provided, and the susceptor 2 and the heating member 11 are heated separately to produce a predetermined temperature in a direction perpendicular to the direction of gas flow in the reaction tube 1 between the susceptor 2 and the heating member 11. It is constructed by forming a temperature distribution region and separately introducing each of the epitaxial growth gases having different decomposition temperatures into the temperature distribution region in the reaction tube 1 close to the decomposition temperature.

(Function) In the method of the present invention, a substrate is placed and heated, and a heating member is provided facing the susceptor and spaced apart from the susceptor at a predetermined interval in the direction perpendicular to the direction of gas flow in the reaction tube. By heating the heating section separately, a predetermined temperature distribution region is formed along the direction perpendicular to the direction of gas flow in the reaction tube.Then, within this predetermined temperature distribution region, there is a temperature closest to the temperature of the region. The waste introduction end of the epitaxial growth gas having a decomposition temperature of Epiter 1
- Ensure that a clear layer is obtained.

[Example] Hereinafter, an example of the present invention will be described in detail using the drawings.

As shown in FIG. 1 described above, the apparatus used in the method of the present invention includes a CdTe epitaxial growth substrate 3 installed, and a quartz glue sezoter 2 equipped with an infrared lamp 12 inside a reaction tube 1. do. Furthermore, the susceptor 2 and pair 1
ij] An infrared lamp 13 is installed inside the reaction tube 1 at a predetermined interval in a direction perpendicular to the direction of gas flow; a heating member 11 made of quartz ξ is not installed 7.

In addition, 2L of gas introduction pipes for epitaxial growth are installed in the reaction@1.
Insert 22 and 23, respectively.

To carry out the method of the present invention using such an apparatus,
After installing the CdTe epitaxial growth substrate 3 in the septa 2 as described above, the inside of the reaction tube 1 was cleaned with an IQ-5tor.
After evacuation to a degree of vacuum of r, the temperature of the septa 2 is heated to 320°C, and the temperature of the heating member 11 is heated to 400°C. Then, the temperature distribution area in the diametrical direction inside the reaction tube 1 sandwiched between the receptor 2 and the heating member 11 is that the area 31 closest to the heating member 11 has the highest temperature, and the area 32 closest to the susceptor 2 has the highest temperature. The lower temperature region 33 sandwiched between these regions 31 and 32 has a temperature intermediate between the regions 31 and 32.

Therefore, in the waste introduction tube 21 having the introduction end in the region 31 having the highest temperature, there is a descendant having the highest decomposition temperature: an epitaxial growth gas consisting of hydrogen gas carrying L-titellurium is introduced into the region 32 having the lowest temperature. An epitaxial growth gas consisting of hydrogen gas carrying mercury gas is introduced into the waste introduction tube 22 having an end, and the introduction end is introduced into a region 33 having a temperature distribution intermediate between the temperature distributions of regions 31 and 32. Dimethyl cadmilla J, whose decomposition temperature is between the above-mentioned epitaxial growth gases, is introduced into the gas introduction pipe 23 having t','! , 4.1j Introduce an epitaxial growth gas consisting of hydrogen gas.

In this way, the waste introduction tube 21 becomes a diethyl telluric gas introduction tube, the gas introduction tube 22 becomes a mercury gas introduction tube, and the gas introduction tube 23 becomes a dimethyl cadmium gas introduction tube.

Then, the epicooler growth gas introduced from each of the waste introduction pipes 2L22 and 23 is introduced into the temperature distribution region closest to the decomposition temperature of the gas, so that it is reliably decomposed, and the substrate-heater is A high-quality epitaxial crystal that does not cause compositional fluctuations or crystal defects can be obtained.

Incidentally, in the wood embodiment, an infrared lamp was embedded in a quartz member as a susceptor for holding and heating the substrate, and a heating member was used, but graphite was used instead of quartz, and the graphite was heated using high-frequency power. Also good.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, since the epitaxial growth gas can be reliably decomposed, it is possible to obtain a high-quality epitaxial crystal without compositional fluctuation and without occurrence of crystal defects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an apparatus used in the method of the present invention, and FIG. 2 is an explanatory diagram of an apparatus used in a conventional method. In the figure, 1 is a reaction tube, 2 is a susceptor, 3 is a substrate for epitaxial growth, 11 is a heating member, 12.13 is an infrared lamp,
21 is a diethyl tellurium gas introduction tube, 22 is a mercury gas introduction tube, 23 is a dimethyl cadmium gas introduction tube, 3132.
33 indicates a temperature distribution area.

Claims (1)

[Claims] A susceptor (2) that holds and heats a substrate (3) is installed in a reaction tube (1), and epitaxial growth gases having different decomposition temperatures are introduced into the reaction tube (1). In the method of decomposing the epitaxial growth gas by heating the susceptor (2) and attaching the decomposed components of the gas to the substrate (3), the susceptor (2) is heated in a direction perpendicular to the direction of gas flow in the reaction tube (1). The heating member (
11) is provided, and the susceptor (2) and the heating member (1
1) and are heated separately to form a predetermined temperature distribution area (31, 32) in a direction perpendicular to the direction of gas flow in the reaction tube (1) between the susceptor (2) and the heating member (11).
.
) is a vapor phase epitaxial growth method characterized by introducing each layer separately into a layer.