JPH0129242Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to an improvement of a liquid phase epitaxial growth apparatus having a closed structure and using a tilting method.

(b) Technical background Compound semiconductor crystals containing mercury (Hg), such as mercury-cadmium-tellurium (Hg _1-x Cd _x Te) crystals, have a narrow energy gap, making them difficult to use in infrared sensing elements. It is used as a material for forming photoelectric conversion elements.

In order to obtain such a Hg _1-x Cd _x Te crystal in a large area and in a thin layer, which is convenient for device formation, a cadmium tellurium (CdTe) substrate is usually used. A crystal layer of Hg _1-x Cd _x Te is formed on top using a liquid phase epitaxial growth method.

(c) Conventional technology and problems Conventionally, such a liquid phase epitaxial growth method uses a support made of carbon in which a CdTe substrate is embedded, and an Hg ₁ layer that slides on the support to be formed on the substrate. Using a liquid phase epitaxial growth apparatus consisting of a slide member having a liquid reservoir containing a material for forming a crystal layer of _-x Cd _x Te, the apparatus is heated to remove the Hg _1-x Cd _x Te material in the liquid reservoir. After melting the
Move the slide member to place the liquid reservoir on the substrate, then lower the temperature of the heating furnace and place it on the substrate.
A boatslide method is used to form an epitaxial layer of Hg _1-x Cd _x Te.

However, with this method, Hg is easily evaporated.
has the disadvantage that it evaporates from the liquid reservoir into the reaction tube before forming a crystal layer.

Therefore, the inventors of the present invention previously proposed a liquid phase epitaxial growth apparatus having a closed structure as shown in FIG. 1 and using a tilting method.

FIG. 1 is a perspective view of the liquid phase epitaxial growth apparatus according to the above-mentioned proposal, and FIG.
A sectional view taken along line A', Figure 3 is B- in Figure 1.
FIG. 3 is a sectional view taken along line B'.

As shown in FIGS. 1, 2, and 3, the conventional liquid phase epitaxial growth apparatus includes a CdTe substrate 2 and a quartz tube supporting the substrate in a heat-resistant sealed tube 1 made of quartz or the like. The quartz rod 5 is comprised of a pair of quartz rods 5 provided with a recess 4 for holding a supporting plate 3 of the same name between them. Furthermore, a material 6 of Hg _1-x Cd _x Te to be formed on the substrate 2 is placed between the pair of supporting members 5 in the sealed tube 1.
is filled.

The thus sealed tube 1 is introduced into a reaction tube in a heating furnace, and the reaction tube is heated and filled.
After melting the Hg _1-x Cd _x Te material, the sealed tube 1 is rotated 180° in the direction of arrow C. Then the substrate melted Hg _1-x
The substrate will be immersed in a solution of Cd _x Te, and in this state, the temperature of the heating furnace is lowered, and by lowering the temperature of the solution, a crystal layer of Hg _1-x Cd _x Te will be precipitated on the substrate. become.

However, in a liquid phase epitaxial growth apparatus having such a conventional structure, the
On the CdTe substrate 1, the temperature of the solution to be formed on the substrate varies locally due to the heat capacity of the support member, resulting in abnormal growth of the epitaxial layer, or Hg _1-x after the epitaxial layer is grown on the substrate. Cd _x
The Te solution accumulates in the recess 4 of the support member 5 and adheres to the substrate, resulting in abnormal growth of uneven Hg _1-x Cd _x Te crystals on the substrate near the recess. cause inconvenience. If the epitaxial layer grows abnormally on the side edges of the substrate in this manner, that portion must be removed when forming an element, resulting in a disadvantage that the effective area of the substrate for forming an element is reduced.

(d) Purpose of the invention The purpose of the invention is to provide a novel liquid phase epitaxial growth apparatus that eliminates the above-mentioned drawbacks and increases the area of the epitaxial layer formed on the substrate for forming elements. It is something.

(e) Structure of the invention The liquid phase epitaxial growth apparatus of the invention to achieve the above object is inscribed in a heat-resistant sealed tube,
It consists of a pair of support members that sandwich a holder that holds the substrate, and the holder is provided with a recess that exposes the crystal growth surface of the substrate and holds the substrate, and the recess is
It is provided at a position separated from the recess of the support member that holds the holder.

(f) Embodiment of the invention An embodiment of the invention will be described below in detail with reference to the drawings. Figure 4 is a cross-sectional view of the liquid phase epitaxial growth apparatus of the present invention, and Figures 5a to 6c are
7A to 7C are plan views and cross-sectional views of the substrate holder used in the growth apparatus of the present invention, and FIGS. 7a to 7c are plan views and cross-sectional views of the substrate used in the present invention.

As shown in FIG. 4, the liquid phase epitaxial growth apparatus of the present invention includes a holder 12 made of two quartz plates that embeds and holds a CdTe substrate 11 with tapered sides on a pair of opposing sides. It is formed by a support member 14 made of a pair of quartz rods having a recess 13 for inserting and supporting the holder 12, and is made of a heat-resistant material that is inscribed with these support members (not shown in the figure). It is housed in a sealed tube made of quartz. As shown in the figure, a CdTe substrate 11 is embedded and supported in a holder 12 at a distance from a recess 13 of a support member 14. To explain this type of holder 12 in detail, it consists of two lower quartz plates 12A and an upper quartz plate 12B, as shown in FIGS. 5a to 6c. FIG. 5a is a plan view of the lower quartz plate 12A;
FIG. 5b is a cross-sectional view taken along line D-D' in FIG. 5a, and FIG. 5c is a cross-sectional view taken along line E-E' in FIG. 5a. As shown in the figure, the lower quartz plate 12A has a thickness of about 1
A depression 15 with a depth of about 0.1 mm is provided in the center of a rectangular quartz plate with a diameter of about 0.1 mm, in which the bottom surface of a CdTe substrate 11 is placed.

6a is a plan view of the upper quartz plate 12B, FIG. 6b is a sectional view taken along the line F-F' in FIG. 6a, and FIG. 6c is a sectional view taken along the line G-G' in FIG. 6a. FIG. As shown in the figure, the upper quartz plate 12B is a rectangular quartz plate with a thickness of approximately 1 mm, and has an inclined surface 1 at the center of the rectangular quartz plate having the same angle as the taper of the side surface of the CdTe substrate 11.
A hole 17 having a diameter of 6 is provided by hollowing out the quartz plate 12B.

FIG. 7a is a plan view of a CdTe substrate used in the device of the present invention, FIG. 7b is a sectional view taken along line H-H' in FIG. 7a, and FIG. A CdTe substrate 1 shown in Figure 7b in cross section along the -K' line.
The angle of the sloped surface 18 on the pair of side surfaces of the upper quartz rod 12B is polished using an angle polisher or the like so that the angle of the sloped surface 18 is equal to the angle of the sloped surface 16 of the central opening 17 of the upper quartz rod 12B.

After that, the substrate 11 is placed in the recess 1 of the lower quartz plate 12A.
5, then place the upper quartz plate 12B on top of it.
The substrates are overlapped so that the openings 17 of the substrates are fitted into the substrates. The holder 12 in which the quartz plates 12A and 12B thus constructed are superimposed is fitted into the recess 13 of the support member 14 as shown in FIG. 4, and sealed in the sealed tube 1 as shown in FIG. do. A material for forming a crystal layer to be formed on a substrate, such as Hg _1-x Cd _x Te, is filled between the supporting members 14 in the sealed tube, and then the inside of the sealed tube 1 is evacuated and sealed. After that, such a sealed tube is inserted into a heater to melt the crystal layer forming material, and then the sealed tube is tilted in the direction of arrow C and placed on the substrate.
After contacting the Hg ₁ -xCdxTe solution, the temperature of the heater is lowered to form an epitaxial layer of Hg _1-x Cd _x Te on the substrate.

In this way, the substrate 11 and the recess 13 of the support member 14 are separated from each other, and abnormal growth of the epitaxial layer on the side edges of the substrate 11 can be avoided. The formation of an epitaxial layer can be avoided, resulting in the advantage that the effective area of the epitaxial layer for device formation is increased.

(g) Effect of the invention As described above, according to the liquid phase epitaxial growth apparatus of the invention, the substrate is held at a distance from the recess of the support member that accommodates the holder that holds the substrate. Abnormal growth of the epitaxial layer on the side edges of the substrate due to solution accumulating in the recesses on the side edges of the substrate is avoided, and the supporting member 1
The heat capacity of 4 prevents the epitaxial layer from abnormally growing on the side edges of the substrate, resulting in the advantage that an epitaxial layer with a wide effective area for device formation can be obtained.

[Brief explanation of the drawing]

1 to 3 are perspective views and sectional views of a conventional liquid phase epitaxial growth apparatus, FIG. 4 is a sectional view showing an embodiment of the liquid phase epitaxial growth apparatus of the present invention, and FIG. 5 5a is a plan view of the lower holder, FIG. 5b is a sectional view taken along line D-D' in FIG. 5a, and FIG. 5c is a sectional view taken along line EE' in FIG. 5a. , Fig. 6a is a plan view of the upper holder, Fig. 6b
is a sectional view taken along the line F-F' in Fig. 6a, Fig. 6c
6 is a sectional view taken along the line G-G' in FIG. 6a, and FIGS. 7a to 7c are a plan view and a sectional view of the substrate used in the apparatus of the present invention. In the figure, 1 is a sealed tube, 2 and 11 are CdTe substrates,
3 and 12 are holders, 4 and 13 are recesses, 5 and 14 are support members, 6 is a material of Hg _1-x Cd _x Te, 15 is a depression, 16 and 18 are inclined surfaces, 17 is an opening, C indicates an arrow indicating the direction of rotation.

Claims (1)

[Scope of utility model registration request] It consists of a pair of support members that are inscribed in a heat-resistant sealed tube and sandwich a holder that holds the substrate, and the holder is provided with a recess that exposes the crystal growth surface of the substrate and holds the substrate, and the recess is connected to the holder. 1. A liquid phase epitaxial growth apparatus, characterized in that it is provided at a position separated from a recess of a support member that holds a tool.