JPS5918645A - Liquid phase epitaxial growth apparatus - Google Patents

Abstract

PURPOSE:To obtain a high quality epitaxial growth film under normal temperature by accommodating the component which is easily vaporized in the epitaxial layer forming material within a recess formed at a part of fine tube connected to a hermetically sealed reservior, heating it under the control, balancing a divided pressure thereof with a vapor pressure of epitaxial growth solution within the reservior and moreover providing an exhaust valve. CONSTITUTION:The Hg1-xCdxTe 16 and CdTe substrate 16 are accommodated within a reservior 11 under the support by a bar 13 and the inside is exhausted to the vacuum condition. The heaters 17, 21 are set respectively to 500 deg.C, 300 deg.C, H2 is supplied to a fine tube 18. When vapor pressure of reservoir is 1kg/cm<2>, a gas is introduced from a valve 14 and a divided pressure of Hg 20 within a recess 19 is balanced to the vapor pressure of reservoir 11 by adjusting the heater 21. Next, the solution 12 is dipped into the solution 16, temperature of heater 17 is lowered with the specified gradient. Thereby, an epitaxial layer of Hg1-xCdxTe is provided on the substrate and then substrate is lifted after the specified period. The space 23 in the reservoir 11 is saturated by the Hg vapor and high pressure is no longer necessary for preventing evaporation from the matrial 16. Moreover, unwanted material 16 falls by its own weight while it is lifted and thereby a high quality epitaxial layer can be obtained without surface damage, unlike the sliding method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in a liquid 411 epitaxial 1j35 length device.

(To) Background of the technology Materials for forming photoelectric conversion elements such as infrared sensing elements include mercury, cadmium, and Terrell (Hgx-xCdxTe).
It is well known that compound semiconductor crystals with narrow energy gaps such as those shown in (a) are used. CdTe (
T (g 3-Xc
A method has been adopted in which dXTe crystals are formed by a phase-phase p-growth method.

(C1 Prior Art and Problems) Furthermore, as a long method for liquid-phase shrimp taxa, there is a method called the dipping method as shown in FIG.

As shown in the figure, the apparatus used in this method moves vertically within an airtight container l made of quartz or the like.
A support rod 8 is installed to hold the substrate 2 made of e.

On the other hand, the container 1 is filled with alloy 4 of f(gl zcd-zTe, which is the material of the crystal layer to be formed on the substrate 2J), and the interior of the container 1 is evacuated. In order to prevent easily evaporable Hg from evaporating when alloy 4 of HR: t-xCdXTθ is melted in space 5 of the container, 10 kt of inert gas of 9 is supplied to argon (Ar) gas through piping 6.
In this state, a heater installed around the container l is heated to give a pressure of l1g.
1-xcd) (dissolve Te monthly charge 4.

After that, the support rod 3 is lowered to lower the substrate 2)(g 1-zC(
After immersing the substrate in the bath solution of IX'Pe, the wetness of the heater 70 is lowered at a predetermined temperature gradient to inject Hg1-xc onto the two substrates.
ctX're is formed, and when the predetermined period of time has ended and the Evita Kinyal layer of a predetermined thickness has been formed on the substrate 2k, the support rod 8 (11-L(gl-)(c
d) (It is moved to the north of the solution of 're to form a layer of Ebitaxia on top of 2.

However, such a method requires maintaining the inside of the container at a high pressure, which has many disadvantages such as damage to the container and loss of material.

A sliding method is a well-known method of this type.

The apparatus used in this method is, as is well known, an epitaxial growth jig comprising, for example, a rectangular parallelepiped support made of carbon and a slide portion AA that slides on the support. And on the FlIJ record stand there is a C.
A recess for embedding the dTe substrate is provided, and the substrate is buried in the recess, and an axillary sump in the form of an oil hole from t to ib is provided in the slide member, and the substrate 1 is formed in this sump. Hg1~x
Cd) (Te material is filled. Then, in this state, a jig for Ebitakisha) V growth consisting of a support stand and a slide member is inserted into a reaction tube in a hydrogen (Hg) gas atmosphere, and the reaction tube is placed in a heater. Heat it to [(Hg in the f reservoir 1-X
ca, ) ('re melting material. After that, move the slide member and leave the waste on the substrate, and then lower the temperature of the heater. ) Substrate k K Hg 1
-xccj-xTe I) This is a method of forming the entire crystal layer.

However, with this method, if the thickness of the substrate Cd']'e is one inch greater than the depth of the recess of the buried support, the bottom surface of the core H may damage the substrate surface when the slide member is moved. Furthermore, if the thickness of the CdTe substrate is smaller than the depth of 4-9r, even if the slide member is moved after epitaxial growth, unnecessary Hg remaining in the filamentous soil after epitaxial growth will be generated.
This results in the disadvantage that the solution where l zed>H'l'e cannot be sufficiently wiped away. Therefore, it is necessary to precisely polish the thickness of the substrate, which has the disadvantage that the number of earthworks required is too long.

In addition, the above-mentioned Nufiting method generally causes scratches on the substrate surface when moving the slide member, and unnecessary Hg that remains on the substrate after forming the epitaxial layer.
1-) (The CdXTe solution cannot be sufficiently wiped away, which has many drawbacks, such as crystal defects occurring in the Evita Kinya p layer formed on the substrate.

(tjJ 1.Object of the Invention The present invention eliminates the above-mentioned drawbacks, and eliminates the need for a complex device that requires a high resistance as in the case of forming an epitaxial layer by the tipping method.
It is possible to obtain a high-quality epitaxial crystal layer using a device that can operate at normal pressure of /CN2, and does not cause scratches on the crystal layer on the surface of the substrate as in the 7 Leydenk method. The purpose of this invention is to provide a novel liquid phase epitaxial growth apparatus.

fe) Structure of the Invention In order to achieve the above object, the surface phase epitaxial growth apparatus of the present invention supports the substrate with a support rod into an epitaxial layer growth solution housed in an airtight container, and then immerses the substrate to form an epitaxial layer on the substrate. In the apparatus for growing j-,
A thin tube communicating with the airtight container and having a recess for accommodating an easily evaporable component of the material for epitaxial layer growth is installed in a part thereof, and A heater is provided to balance the vapor pressure of the solution in the airtight container, and an exhaust pipe having an exhaust valve is provided in the airtight container.

([) Embodiment of the Invention An embodiment of the invention will be described below in detail with reference to the drawings.

FIG. 2 is a schematic diagram of the two-night phase epitaxial growth apparatus of the present invention. As shown in the figure, a CdTe substrate 12f is placed in a quartz container 2 with an airtight structure, and a CdTe substrate 12f is placed on a support.
(!I) A support rod 13 made of quartz is installed in the container 11. Also, an exhaust pulp 14 for exhausting the inside of the container is installed in the container 11.
An exhaust pipe 15 having a substrate 12. is connected to the container, and a substrate 12. J
: Material of crystal layer to be formed (7) Hg 1-xCd
The container 11 is filled with xTe material 16, and a heater 17 for heating the container 11 is provided around the container 11.

On the other hand, a thin tube 18 is provided in communication with the container 11, and this thin tube 1
A bulging recess 19 is provided in the middle of the substrate 8, and mercury (Hg) 20, which is easily evaporated out of the Hg 1-xCdxTe material to be formed on the substrate, is accommodated in the recess. A partial pressure control heater 21 for controlling the vapor pressure of mercury 20 is provided around this recess 19.

II on the CclTe substrate 12 using such a device.
(The case where a crystal of gl-zcdXTe is grown epitaxially will be described.

'1. fm closed fA 22 open) (gx-xcd
After filling the materials 16 of x' and ['e, the substrate 12 placed on the support rod 18 is inserted into the container 11.

After that, open the pulp 14 inside the container ll and vacuum J? After that, the pulp 14 is closed and the temperature of the heater 17 is 50071;
The temperature of the heater 21 is set to 300° C., and hydrogen (Hg) gas is introduced into the thin tube 18 as indicated by arrow A. Then, when the vapor pressure in the container 11 reaches 1 kg 7 cmg, the pulp 4 is opened and gas is introduced into the thin tube, and the temperature of the heater 21 is adjusted so that the partial pressure of the mercury 20 in the recess 19 is reduced to 1 kg. The vapor pressure should be in equilibrium with the vapor pressure of After that, the support rod 18 is lowered and the Hg1-XCdXTeo melts 0.
Hg 1-
XCd)('l'e (7) Form a crystal layer.

After a predetermined period of time has elapsed, the support rod 18 is pulled upwards and the shrimp taxa 7 is pulled up to stop the growth.

In this way, the space 23 inside the container 11 is
The space 23 is filled with high-pressure Ar gas as in the conventional method, and Hg evaporates from the 4J material of Hg1-yCdXTθ in the container into the space 28. Approximately 1kg/cm without the need to prevent
Epitaxial growth is possible at normal pressure.

By moving the substrate 12 to the north after the epitaxy and growth, the Hg 1-xCαXT attached to the plate is removed.
The solution in e also easily falls downward due to its own weight, causing scratches on the substrate surface as in the conventional sliding method, and the phenomenon in which unwanted Hgt-xC (IXTe solution) adheres to the substrate after growth. A high-quality epitaxial layer can be easily obtained using a simple device.

Effects of the Invention As described above, according to the liquid phase epitaxial growth method of the present invention, there is no need to maintain the pressure inside the container at a high pressure, and a high quality epitaxial layer that does not cause scratches on the substrate can be obtained. Produces profit, v,.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus used in a conventional liquid phase epitaxial growth method, and FIG. 2 is a schematic diagram of a device used in a conventional liquid phase epitaxial growth method.
t is a four-electrome diagram of the device used in the long method. 1.11 is an airtight container, 2 and 12 are Cd-Te substrates, 8,
[8 is the support rod, 4.16 is t(gl-xCdz'L”e
material, 5.23 is the space, 6.15 is the exhaust pipe, 7゜1
7 is a heater, 18 is a thin tube, 19 is a recess, 20 is mercury, 2
1 is a partial pressure control 1-+1 heater, and A is an arrow indicating water retention in the gas introduction direction.

Claims (1)

[Claims] In an apparatus in which a substrate supported by a support rod is immersed in an epitaxial layer growth solution housed in an airtight container and a layer is grown on the substrate by epitaxy, the epitaxial layer is formed in a part of the epitaxial layer in communication with the airtight container. A thin tube having a recess for accommodating an easily evaporable component of the growth material is installed, and the partial pressure of the easily evaporable component and the vapor pressure of the RI liquid in the airtight container are controlled in equilibrium around the recess. 1. A liquid phase epitaxial growth apparatus, characterized in that a heater is provided, and the airtight container is further provided with an exhaust pipe having exhaust pulp.