JPH0582459A - Manufacture of epitaxial crystal - Google Patents

Abstract

PURPOSE:To obtain a crystal growth method capable of omitting a wax coating process and an etching process necessary for thickness measurement of an epitaxial layer, regarding the epitaxial growth on a different kind of substrate. CONSTITUTION:After a crystal layer 2 containing constituent atoms of a compound semiconductor crystal 7 to be formed is subjected to vapor growth on a substrate 1, said substrate 1 having the crystal layer 2 is brought into contact with melt for epitaxial growth. Compound semiconductor crystal 7 constituted of atoms different from constituent atoms of the substrate 1 is grown on the crystal layer 2 by a liquid epitaxial growth method. In this case, the crystal layer 2 is subjected to vapor growth on the substrate 1, the crystal layer 2 in the peripheral part on the substrate 1 is selectively eliminated, the substrate 1 is brought into contact with the melt for epitaxial growth, and the compound semiconductor crystal 7 constituted of atoms different from the constituent atoms of the substrate 1 is formed by a liquid epitaxial growth method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an epitaxial crystal, and more particularly to a method for producing a compound semiconductor crystal composed of atoms which do not contain the constituent atoms of the substrate by a liquid phase epitaxial growth method on the substrate.

[0002]

Narrow energy band gap as a material for forming the Related Art infrared detector element, a compound semiconductor crystal have been used in mercury-cadmium-telluride _{(Hg 1-x Cd x Te} ), the Hg _1-x Cd _x Te In order to grow the sapphire, a sapphire substrate, which is relatively easy to obtain a large-area substrate, is used.

As described above, Hg _1-x Cd _{x is formed} on the sapphire substrate.
When Te is formed by liquid phase epitaxial growth, Fig. 3 (a)
As shown in, MOCVD (Metal O
The cadmium tellurium (CdTe) crystal layer 2 is formed in a thin layer state of about 1 μm by the rganic Chemical Vapor Deposition method.

Next, as shown in FIG. 3 (b), such CdTe
Place the layered sapphire substrate 1 on the jig 4 and press
It is enclosed in an ampoule 6 together with a melt 5 for epitaxial growth obtained by melting and solidifying g, Cd, and Te.

Then, the ampoule 6 is heated to epitaxy.
The char growth melt 5 is melted. And ampoule
6 is rotated in the direction of arrow A to melt the melt on the sapphire substrate 1.
5 to bring the temperature of the melt down as shown in Fig. 3 (c).
Hg down on the substrate 1_1-xCd _xTe crystal 7 epitaxy
Le is growing.

After the Hg _1-x Cd _x Te crystal is epitaxially grown to a predetermined thickness, the ampoule 6 is further attached with an arrow B.
3 (b), the wipe-off operation of wiping off the epitaxial growth melt adhering to the substrate 1 is performed.

In this way, in the heating step for melting the epitaxial growth melt 5, mercury vapor tellurium (HgTe) is supplied by the vapor of the melt 5 for epitaxial growth, and this HgTe is converted into the CdTe crystal layer 2 Cd formed by MOCVD method by causing mutual diffusion with
The Te crystal layer 2 is converted into Hg _1-x Cd _x Te crystal 7.

Then, as shown in FIG. 3 (c), it becomes the same as the Hg _1-x Cd _x Te crystal 7 being epitaxially grown directly on the sapphire substrate 1. The method for producing such an epitaxial crystal will be described in the present application. The person was previously open to the public 2-63432
It is proposed in the issue.

[0009]

[SUMMARY OF THE INVENTION Incidentally, in the above-mentioned epitaxially grown Hg _1-x Cd _x Te surface of the crystal, is solidified residual melt of the molten epitaxial growth melt during liquid phase epitaxial growth, Hg _1-x In many cases, it adheres to the surface of the Cd _x Te crystal, and its thickness may reach 1000 μm in extreme cases.Therefore, this residual melt may hinder the subsequent mask alignment process. is there.

The residual melt is the melt for epitaxial growth which was not removed by the above-mentioned wipe-off operation and remained and adhered to the surface of the Hg _1-x Cd _x Te crystal.

The measurement of the thickness of the epitaxial layer of the Hg _1-x Cd _x Te crystal in the case where the residual melt is adhered by such epitaxial growth will be described. As shown in the plan view of FIG. 4 (a), the sapphire substrate 1 on which an Hg _1-x Cd _x Te crystal has been epitaxially grown is formed along the longitudinal direction of the sapphire substrate 1 as shown by dotted lines D at both ends. The region of the Hg _1-x Cd _x Te crystal where the residual melt is formed is cut together with the substrate 1 by cutting.

Next, as shown in the sectional view of FIG. 4 (b), masking tapes 8 are attached to both ends of the epitaxially grown Hg _1-x Cd _x Te crystal 7 in the lateral direction, and then wax 9 is applied. Then, after the masking tape 8 is peeled off, Hg is removed by etching using the wax 9 as a mask.
The epitaxial crystal 7 of _1-x Cd _x Te is removed, and the Hg _1-x Cd _x Te crystals 7 at both ends in the lateral direction of the substrate 1 are selectively removed to expose the sapphire substrate 1 to expose the sapphire substrate 1 as shown in FIG. The shape shown in the sectional view of c) is used.

Next, as shown in the sectional view of FIG. 4 (d), a measuring needle 11 for measuring the thickness is erected on the surface of the sapphire substrate 1, and the measuring needle 11 is moved in the direction of arrow F. Then, the value of the step between the surface of the sapphire substrate 1 and the surface of the Hg _1-x Cd _x Te crystal 7 is detected, and the thickness of the epitaxially grown Hg _1-x Cd _x Te crystal 7 is measured by this value.

Then, this measurement is performed at a plurality of points on the substrate, and the average value of the thickness of the epitaxial crystal is calculated based on the values. However, in order to measure the thickness of the Hg _1-x Cd _x Te crystal epitaxially grown in this way, the step of attaching a masking tape on the sapphire substrate, the step of applying wax, or the step of etching is complicated. Therefore, a simple method is desired without taking such complicated steps.

The above masking tape is Hg _1-x
A solidified residual melt is formed on the Cd _x Te crystal 7 and it is difficult to attach it to a given size with high precision, so that the precious Hg _1-x Cd _x Te crystal region is excessively etched. Causes inconvenience.

When the above-mentioned residual melt is formed on both ends of the substrate, in order to remove the residual melt,
It is necessary to etch the Hg _1-x Cd _x Te crystal in excess of the etching area required to measure the thickness of the epitaxial growth layer, which hinders device formation.

The present invention solves the above-mentioned problems, and the epitaxial crystals of Hg _1-x Cd _x Te are removed at both ends of the substrate without the need for complicated wax coating and etching operations. It is intended to provide a method for producing crystals.

Another object of the present invention is to provide a manufacturing method in which the above-mentioned residual melt is prevented from being formed in the epitaxially grown Hg _1-x Cd _x Te crystal.

[0019]

According to the method for producing an epitaxial crystal of the present invention, a crystal layer containing constituent atoms of an epitaxial crystal to be formed is vapor-phase grown on a substrate, and then the substrate having the crystal layer is used for epitaxial growth. In contact with the melt, when growing a compound semiconductor crystal composed of atoms different from the constituent atoms of the substrate on the crystal layer by liquid phase epitaxial growth method, after vapor phase growth of the crystal layer on the substrate, After selectively removing the peripheral crystal layer on the substrate,
The substrate is brought into contact with a melt for epitaxial growth, and a compound semiconductor crystal composed of atoms different from the constituent atoms of the substrate is formed by the liquid phase epitaxial growth method.

Further, after vapor-depositing the crystal layer on the substrate, the peripheral crystal layer on the substrate is covered with a shielding jig, and then the substrate is brought into contact with the melt for epitaxial growth to form a liquid phase. It is characterized in that a compound semiconductor crystal composed of atoms different from the constituent atoms of the substrate is formed by the epitaxial growth method by the liquid phase epitaxial growth method.

[0021]

After the CdTe crystal is formed on the sapphire substrate by the vapor phase growth method, both ends of the CdTe crystal are selectively etched and removed to expose the surface of the sapphire substrate. Then, since the Hg _1-x Cd _x Te crystal is not epitaxially grown on this sapphire substrate, a wax coating step for forming a step for thickness measurement and an etching step can be omitted in a later step.

Further, the above-mentioned residual melt will not be formed at both ends of the epitaxially grown Hg _1-x Cd _x Te crystal. In addition, using a shielding jig that covers both end surfaces of the sapphire substrate on which the CdTe crystal is formed so that the Hg _1-x Cd _x Te crystal to be etched does not grow, Hg _1-x
When Cd _x Te liquid phase epitaxial growth of crystals, after step in Hg _1-x Cd _x Te crystal selectively etching process can be omitted.

Further, the above-mentioned residual melt will not be formed on both ends of the epitaxially grown Hg _1-x Cd _x Te crystal.

[0024]

Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1 (a), the sapphire substrate 1
A CdTe crystal layer 2 is formed on the top of the CdTe crystal layer 2 in a thin layer with a thickness of about 1 μm by MOCVD.

Next, as shown in FIG. 1 (b), a resist film 21 is applied on a predetermined region of the sapphire substrate 1 on which the CdTe crystal layer 2 is formed, and an etching solution for the CdTe crystal layer (mixing of bromine and methyl alcohol is used). Liquid) is used to selectively etch the CdTe crystal layer.

This CdTe crystal layer is formed by the MOCVD method, and its surface is formed in a smooth state. After applying the resist film 21, the mask alignment for exposing the resist film 21 can be performed with high accuracy. Cd that can be etched because it can be done
The dimensions of the Te crystal layer 2 are highly accurate.

Then, as shown in FIG. 1 (c), the liquid phase epitaxial growth method shown in FIG. 3 (b) is applied to the substrate 1 having the CdTe crystal layer 2 whose both ends are selectively etched in this way. Using, the Hg _1-x Cd _x Te crystal 7 is grown by liquid phase epitaxial growth as shown in FIG. 1 (d).

By doing so, the sapphire substrate 1 is exposed.
Hg_1-xCd_xTe crystal 7 formed epitaxially
Since it is not long, it can be selectively used at locations excluding both ends of the substrate 1.
To Hg _1-xCd_xTe crystal 7 was epitaxially grown,
In the process, the wad necessary for measuring the thickness of the epitaxial growth layer is
The box coating work and the etching process can be omitted.

Further, by doing so, no residual melt is formed on both ends of the substrate. In addition, as a second embodiment of the present invention, as shown in FIG. 2 (a), the sapphire substrate 1 on which the CdTe crystal layer 2 is formed is attached to a shielding jig 22 made of a quartz plate which selectively covers both ends of the substrate. Install 1. Next, with the substrate 1 placed on the shielding jig 22, the sapphire substrate 1 is embedded in a carbon jig 4 for epitaxial growth and placed as shown in FIG. Along with this, it is sealed in the ampoule 6.

In this way, since the Hg _1-x Cd _x Te crystal does not grow epitaxially in the portion of the sapphire substrate covered by the shielding jig 22, the portions other than the both ends of the substrate are selectively removed. The Hg _1-x Cd _x Te crystal is epitaxially grown, and the wax coating operation and etching step necessary for measuring the thickness of the epitaxial crystal in the subsequent steps can be omitted.
Further, unnecessary residual melt is not formed at both ends of the Hg _1-x Cd _x Te crystal.

[0031]

As described above, according to the method of the present invention, after Hg _1-x Cd _x Te crystals are epitaxially grown,
_This eliminates the need for wax coating and etching required for measuring _1-x Cd _x Te epitaxial crystals, which has the effect of reducing the number of steps in the etching crystal manufacturing process.

Further, there is an effect that unnecessary residual melt is not formed at both ends of the Hg _1-x Cd _x Te crystal.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing method of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing method of the present invention.

FIG. 3 is an explanatory diagram of a conventional manufacturing method.

FIG. 4 is an explanatory diagram of a conventional manufacturing method.

[Explanation of symbols]

1 Sapphire substrate 2 CdTe crystal layer 4 Jig 5 Epitaxial melt 6 Ampule 7 Hg _1-x Cd _x Te crystal 21 Resist film 22 Blocking jig

Claims (2)

[Claims] 1. A crystal layer (2) containing constituent atoms of a compound semiconductor crystal (7) to be formed is vapor-phase grown on a substrate (1), and then a substrate (1) having the crystal layer (2) is formed. A compound semiconductor crystal (7) composed of atoms different from the constituent atoms of the substrate (1) on the crystal layer (2) brought into contact with the melt for epitaxial growth (5)
When the crystal layer (2) is grown on the substrate (1) by vapor phase epitaxy, the substrate (1)
After selectively removing the upper peripheral crystal layer (2), the substrate (1) is brought into contact with the epitaxial growth melt (5),
A method for producing an epitaxial crystal, which comprises forming a compound semiconductor crystal (7) composed of atoms different from the constituent atoms of the substrate (1) by a liquid phase epitaxial growth method. 2. A crystal layer (2) containing constituent atoms of a compound semiconductor crystal (7) to be formed on a substrate (1) is vapor-phase grown, and then a substrate (1) having the crystal layer (2) is formed. A compound semiconductor crystal (7) composed of atoms different from the constituent atoms of the substrate (1) on the crystal layer (2) brought into contact with the melt for epitaxial growth (5)
When the crystal layer (2) is grown on the substrate (1) by vapor phase epitaxy, the substrate (1)
After covering the upper peripheral crystal layer (2) with the shielding jig (22), the substrate (1) was melted for epitaxial growth (5).
Compound semiconductor crystal composed of atoms different from the constituent atoms of the substrate by a liquid phase epitaxial growth method (7)
Is formed by a liquid-phase epitaxial growth method.