JPS63220529A - Manufacture of semiconductor crystal - Google Patents

Abstract

PURPOSE:To make the thickness of an epitaxial crystal uniform by forming the thickness of the solution of a semiconductor material, which is brought into contact with a substrate and shaped under the substrate when a reaction tube is turned, in thicker size at the central section of the substrate than the peripheral section of the substrate. CONSTITUTION:The depth l1 of the solution of a semiconductor material 12 brought into contact with a substrate 11 and positioned at the lower section of the central section of the substrate 11 is made deeper than the depth l2 of the solution of the semiconductor solution 12 in the lower section of the peripheral section of the substrate 11, and the quantity of a solute in the lower section of the unit area of the central section is made larger than that of the solute in the lower section of the unit area of the peripheral section. Consequently, since the quantity of the solute under the unit area of the substrate 11 is made larger than that of the solute under the unit area of the peripheral section even when there is a tendency in which the quantity of diffusion of the solute reaching the peripheral section of the substrate 11 is made larger than that of the solute reaching the central section of the substrate 11, the quantity of diffusion of the solute in the solution under the central section of the substrate and the quantity of diffusion of the solute in the solution under the peripheral section of the substrate are equalized. Accordingly, an epitaxial crystal having uniform thickness and an equal composition is formed onto the substrate.

Description

[Detailed Description of the Invention] [Summary] This is an improvement of the tilted liquid phase epitaxial growth method, in which the substrate is rotated to bring the substrate into contact with a solution of a melted epitaxial layer forming material to lower the temperature of the solution. When forming an epitaxial layer on a semiconductor substrate, the depth of the solution in contact with the semiconductor substrate is set so that it is deep at the center of the substrate and shallow at the periphery of the substrate, so that the amount of diffusion of the solute in the solution with respect to the substrate surface is It is made to be uniform over the entire surface of the substrate, so that an epitaxial crystal having a uniform thickness and a uniform composition can be obtained on the substrate.

[Industrial application field]

The present invention relates to a liquid phase epitaxial growth method, and particularly to a tilted liquid phase epitaxial growth method.

Compound semiconductor substrates such as mercury, cadmium, and tellurium, which have a narrow energy band gear, are used as materials for infrared sensing elements.

Since mercury, cadmium, and tellurium are elements that evaporate very easily, in order to form this compound semiconductor crystal without causing compositional fluctuations, it is necessary to form the mercury, cadmium, and tellurium on a substrate with a simple device configuration. A tilted liquid phase epitaxial growth method is used in which a solution of a material for forming an epitaxial crystal is sealed in a sealed container.

In such a tilted liquid phase epitaxial growth method, it is desired to form a uniform &J1 growth on the root and an epitaxial crystal having a uniform thickness.

[Conventional technology]

FIG. 3 is a cross-sectional view of a liquid phase epitaxial growth apparatus used in such a method. As shown in the figure, a reaction tube 1 with a bottom at one end has a concave hollow in the center and a cylindrical quartz tube. A support member 2 consisting of the following is installed so as to be in contact with the inner wall of the reaction tube 1.

A depression (not shown) is provided at a position where the support member 2 faces each other with the four parts 3 in between, and a support plate 4 made of quartz and cadmium tellurium (CdT) for epitaxial growth are provided in the depression.
The semiconductor substrates 5 of e) are installed in a stacked manner, and a semiconductor material 6 of mercury, cadmium, and tellurium for epitaxial growth to be formed on the substrates is housed in the lower part of the semiconductor substrates 5.

In this way, the support plate 4 is attached to the support part shrine 2, and the semiconductor part 1 (plate 5
After accommodating the reaction tube 1 and the semiconductor material 6, the inside of the reaction tube 1 is evacuated, the other end A' is welded and sealed, and then the reaction tube 1 is introduced into a furnace core tube in a heating furnace, and the heating furnace is heated. Semiconductor material 6
to melt.

Next, when the temperature of the molten semiconductor material 6 reaches the saturation temperature of the material, the reaction tube 1 is rotated 180 degrees along the direction of the arrow r3, and the molten semiconductor material 6 and the substrate 5 are
bring into contact with.

Rotate the reaction tube 1 180 degrees in this way and turn it into the fourth position.
FIG. 5 is a cross-sectional view of FIG. 4 and FIG. 5 taken along the line v--v'.

Next, while gradually lowering the temperature of the molten semiconductor material 6 in this state, the molten semiconductor material G was solidified on the substrate 5 to form an epitaxial crystal.

When the epitaxial crystal grown on the substrate reaches a predetermined thickness, the reaction tube I is further rotated 180 degrees in the direction of arrow C to separate the semiconductor material solution 6 from the substrate. Epitaxial crystals were then formed on the substrate 5.

[Problem that the invention seeks to solve]

In such a conventional liquid phase epitaxial growth method, the solute in the solution of the molten semiconductor material 6 reaches the surface of the substrate 5 by diffusion, and the solute is solidified to form an epitaxial crystal.

Here, since the peripheral part of the substrate 5 is fixed to the support member 2, the solute that has reached the substrate -1- collides with the support member 2 and moves to the peripheral part of the substrate 5, and the solute reaches the surface of the substrate 5. It grows as an epitaxial crystal without being dispersed.

On the other hand, the solute that has reached the center of the substrate 5 is easily dispersed in all directions on the surface of the substrate 5, and as shown in FIG. The growth rate of the epitaxial crystal is slow in the central region, resulting in a problem that the thickness and composition of the epitaxial crystal formed on the substrate are not uniform.

The present invention solves the above-mentioned problems, and provides a liquid phase epitaxial growth method in which the solute in the solution that reaches the substrate surface by diffusion becomes uniform, thereby making the thickness of the epitaxial crystal formed on the substrate uniform. The purpose is to provide.

[Means for solving problems]

In the liquid phase epitaxial growth method of the present invention, a semiconductor substrate and a molten semiconductor material are sealed in a reaction tube, and after the semiconductor material is melted, the reaction tube is rotated or tilted to bring the molten semiconductor material into contact with the substrate. In a method for manufacturing a semiconductor crystal on a substrate, when the reaction tube is rotated, the thickness of the semiconductor material solution that comes into contact with the substrate and is formed under the substrate is increased from the periphery of the substrate to the substrate. so that it is thick in the center.

[Effect]

In the liquid phase epitaxial growth method of the present invention, when the reaction tube in which the substrate is installed is rotated and the substrate and the solution of the semiconductor material are brought into contact with each other, the thickness of the solution under the center of the substrate is thicker than the thickness of the solution at the periphery of the substrate. In this way, the amount of solute reaching the central portion of the substrate and the peripheral portion of the substrate by diffusion is equal, so that an epitaxial crystal having a uniform thickness and a uniform composition is formed on the substrate.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram of an apparatus used in the liquid phase epitaxial growth method of the present invention, and FIG. 2 is a cross-sectional view of FIG. 1 taken along the line - H'.

FIG. 1 shows the state when the semiconductor material 12 to be formed on the substrate 11 is melted and the reaction tube 13 is rotated 180 degrees to bring the melted semiconductor material 2 onto the substrate 11 into contact.

As shown in the figure, in the liquid phase epitaxial growth method of the present invention, the depth β of the solution of the semiconductor material 12 in contact with the substrate 11 and below the central portion of the substrate 11 is determined.

is set to be deeper than the depth IV2 of the solution of the semiconductor material 12 in the lower part of the peripheral part of the substrate 11, and by doing so, the amount of solute in the lower part of the unit area in the central part of the substrate can be reduced. is larger than the amount of solute at the bottom of the level area at the periphery of the substrate.

In this way, as described above, even if the amount of solute diffusion reaching the peripheral portion of the substrate 11 tends to be larger than the amount of diffusion of solute reaching the central portion of the substrate 11, Since the amount of solute under unit area at the center is larger than the amount under unit area at the periphery of the substrate, the amount of solute diffused in the solution under the center of the substrate and the amount under the periphery of the substrate are The amount of solute diffusion in the solution becomes equal,
An epitaxial crystal having a uniform thickness and a uniform composition is formed on the substrate.

In order to form the solution in the lower part of the central part of the substrate to be thicker than the solution in the lower part of the peripheral part of the substrate, the support member 1 made of quartz is used to accommodate the solution of the semiconductor material 12 described above.
It is preferable that the depth of the recess 15 formed under the substrate 4 is hollowed out so that the depth is deeper below the center of the substrate than below the periphery of the substrate.

〔Effect of the invention〕

As described above, the liquid phase epitaxial growth method of the present invention has the effect of making the thickness and composition of the epitaxial crystal formed on the substrate uniform.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the liquid phase epitaxial growth method of the present invention, Fig. 2 is a cross-sectional view taken along line nn' in Fig. 1, and Figs. 3 and 4 are explanatory diagrams of the conventional liquid phase epitaxial growth method. 5 is a sectional view taken along the line v-v' in FIG. 4, and FIG. 6 is an explanatory diagram of an inconvenient state when formed by the conventional method. In the figure, 11 is the substrate, 12 is the semiconductor material, 13 is the reaction tube, I4 is the support member, 15 is the recess, and β1 and 12 are the depth dimensions of the solution. Fig. 1 O T closed/lIr-1r' sorrowful look ■ Fig. 3 Fig. 4': 'jr4 exchange^7-V' 1: Tin, n trace surface necessary Fig. 5 I East - Suga 1 , 17 and 1-0 station 2 t county Aji%fJ 1 芦可〔riFigure 6

Claims (1)

[Claims] A reaction tube (13) containing a semiconductor substrate (11) and a molten semiconductor material (12) is rotated or tilted to bring the solution of the molten semiconductor material (12) into contact with the substrate (11). In a method for producing epitaxial crystals on a substrate (11) by lowering the temperature, the reaction tube (
13) is rotated, the depth of the solution of the semiconductor material (12) that comes into contact with the substrate (11) and is formed under the substrate is increased from below the periphery of the substrate (11) to below the center of the substrate (11). A method for manufacturing a semiconductor crystal, characterized by forming the semiconductor crystal to be deep.