JPH0536732A - Jig for liquid phase epitaxial crystal growth and manufacture of multi-component semiconductor crystal using this jig - Google Patents

Abstract

PURPOSE:To provide a plural semiconductor crystal of which the composition is uniform at the surfaces. CONSTITUTION:The title jig has a cut recess 3, where, for example, one part at the center of the periphery of a column is cut off in the direction of the center axis of the column, the outside diameter of, at least, one part of the section corresponding to the cut recess 3 is made smaller than the outside diameter of the section, and this small-diameter part 8 is provided with a through hole 9 which pierces it from the substrate 4 side for crystal growth to the above quartz ampule side 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for liquid phase epitaxial crystal growth and a method for producing a multi-element semiconductor crystal using the jig.

A multi-element semiconductor crystal composed of a plurality of compositional elements,
For example, one of the methods for growing a compound semiconductor crystal of gallium / arsenic, gallium / aluminum / arsenic, etc. on a crystal substrate is to bring a solution of these semiconductors as a solute into contact with the crystal substrate at a high temperature and then gradually increase the temperature. There is a method in which a lowered semiconductor crystal is deposited and grown on a substrate.

This method is generally called a liquid phase epitaxial crystal growth method, and is widely adopted as a method for growing a single crystal having high purity and good crystallinity, particularly in the field of semiconductor industry. In recent years, photoelectric conversion elements such as infrared detection elements and infrared semiconductor laser elements have been manufactured using compound semiconductor crystals such as lead, tin, tellurium, and mercury, cadmium, tellurium, etc. containing easily evaporative constituent elements as constituent materials. The above method has been used to do this.

In particular, when a multi-element semiconductor crystal containing easily vaporizable component elements is manufactured by liquid phase epitaxial growth, in order to prevent the solution concentration from changing due to evaporation, crystal growth is performed in a closed container such as a quartz ampoule. And the optimization of the method is being sought.

[0005]

2. Description of the Related Art An example of a conventional method for producing a multi-element semiconductor crystal by liquid phase epitaxial crystal growth will be described with reference to FIG. Reference numeral 1 is a liquid phase epitaxial crystal growth jig. This jig cuts a part of the center of the outer circumference of a cylinder made of, for example, quartz glass or carbon material and having an outer diameter inscribed in a quartz ampoule 2 and a predetermined length. It has a notched recessed portion 3 that is cut out, and is configured to horizontally hold the crystal growth substrate 4 horizontally across the opposing wall surfaces in the notched recessed portion 3.

During the liquid phase epitaxial crystal growth, a crystal growth substrate 4 made of CdTe is held horizontally in the notched recess 3 and the jig 1 and
A melt material 5 for crystal growth composed of Hg, Cd, and Te, which has been weighed in a predetermined composition ratio in advance, is placed in a quartz ampoule 2 as shown in the figure, and the quartz ampoule is hermetically sealed after exhausting the inside of the ampoule. Stop.

Thereafter, the quartz ampoule 2 is placed in an electric furnace (not shown) and heated to a predetermined temperature higher than the crystal growth temperature to melt the melt material 5 in the quartz ampoule 2 and rotate the quartz ampoule 2 by 180 °. Then, the melted melt material is brought into contact with the surface of the crystal growth substrate 4 and the heating temperature is lowered to a predetermined crystal growth temperature to thereby bring the crystal growth substrate 4 into contact.
A single crystal layer of Hg _1-x Cd _x Te is grown on top.

Next, when the single crystal layer having a predetermined thickness is formed, the quartz ampoule 2 is rotated again by 180 ° to remove the melt material on the crystal growth substrate 4 and stop the crystal growth. The quartz ampoule 2 is pulled out from the furnace while being gradually cooled, the quartz ampoule 2 is opened, and the substrate 4 on which the single crystal layer is formed is taken out.

[0009]

The problems in the conventional method will be described with reference to FIG. FIG. 4 is a view showing the distribution of the thickness and composition of the crystal layer 20 grown on the crystal growth substrate 4. This figure is the view of the crystal layer from the axial direction of the quartz ampoule.

The crystal layer 20 is thin in the central portion and thicker in the edge portion of the crystal growth substrate 4, and the equicomposition surface indicated by the broken line is also curved corresponding to such a curved surface shape. Specifically, the isocomposition plane is almost parallel to the hetero interface (bonding surface with the substrate for crystal growth, that is, a plane) up to a thickness of about 30 μm, but the thickness of the crystal layer is more than that. Then, the isocomposition surface is curved.

When an infrared sensing element is formed by using a mercury-cadmium-tellurium crystal, the crystal is required to have a thickness of 40 μm or more and a uniform thickness. Therefore, when the crystal growth surface is curved as described above, it is necessary to correct the curved surface by polishing or the like to make the thickness uniform. However, when polishing is performed so that the crystal having a curved crystal growth surface has a uniform thickness, a large number of isocomposition surfaces are exposed on the crystal surface, which causes a composition gradient on the crystal surface. When a composition gradient is generated on the crystal surface, uniform characteristics cannot be obtained when forming an infrared detection element.

The present invention was created in view of such circumstances, and an object thereof is to enable provision of a multi-element semiconductor crystal having a uniform composition on the crystal surface.

[0013]

A jig for liquid phase epitaxial crystal growth according to the present invention has a notched concave portion formed by cutting out a part of the center of the outer peripheral portion of a cylinder in the direction of the central axis of the cylinder. A jig for holding a crystal growth substrate in a notched recess and enclosing it in a quartz ampoule together with a melt material, wherein at least a part of the outer diameter of the part corresponding to the notch recess is larger than the outer diameter of the other part. Also, the small diameter portion is provided with a through hole penetrating from the crystal growth substrate side to the quartz ampoule side.

The method for producing a multi-element semiconductor crystal of the present invention using this liquid phase epitaxial crystal growth jig comprises the steps of vacuum-sealing the jig together with the crystal growth substrate and the melt material in the quartz ampoule. , A step of horizontally supporting the quartz ampoule so that the notched concave portion faces downward and melting the melt material by heating, and rotating the quartz ampoule by 180 ° to transfer the molten melt material to the substrate for crystal growth. The method comprises the steps of contacting and performing crystal growth, and rotating the quartz ampoule again by 180 ° to prevent the molten melt material from coming into contact with the crystal growth substrate.

[0015]

[Operation] As a result of repeated experiments and consideration by the inventor,
It has been presumed that the cause of the nonuniform thickness of the crystal layer in the case of the conventional method is as follows.

That is, comparing the amount of molten melt material involved in growing a unit amount of crystals in the central portion of the substrate with the amount of molten melt material involved in growing a unit amount of crystals in the edge portion of the substrate, the latter is compared. Is larger, and since the amount of the molten melt material is finite, the thickness of the crystal layer in the central portion of the substrate is relatively small.

It is expected that the convection of the molten melt material in the quartz ampoule will eliminate the non-uniformity of the solute concentration of the molten melt material at the central portion and the edge portion of the substrate. Since the depth of the molten melt material at that time is shallow, the above problem has not been solved yet.

The present invention employs a jig configuration in which the molten melt material is positively convected during crystal growth. In the liquid phase epitaxial crystal growth jig of the present invention, the outer diameter of at least a portion of the portion corresponding to the cutout recess is made smaller than the outer diameter of the other portion, and the through hole is formed in this small diameter portion. Since the melt-melting material is provided in contact with the substrate for crystal growth to perform crystal growth, the melt-melting material easily convects through the outer periphery of the small-diameter portion and the through hole in the quartz ampoule. The effective volume of the molten melt material for the is increased. As a result, it is possible to prevent the thickness of the crystal layer from becoming nonuniform, and it is possible to provide a multi-element semiconductor crystal having a uniform composition on the crystal surface.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a jig for liquid phase epitaxial crystal growth showing a preferred embodiment of the present invention,
This jig 1 has a notched recess 3 formed by cutting out a part of the center of the outer peripheral part of a cylinder made of quartz glass in the direction of the central axis of the cylinder.
have.

In this embodiment, the crystal growth substrate 4 made of CdTe is supported by a substrate holder 6 made of quartz glass, and the substrate holder 6 is cut out to form grooves 7 and 7 formed on the opposite wall surfaces of the recess 3. The substrate is laid horizontally in the cutout recess 3 by being fitted into.

The outside diameter of at least a part (all in this example) of the portion of the jig 1 corresponding to the cutout recess 3 is smaller than the outside diameter of the other portion. In the following description, this small-diameter half-column portion is referred to as the small-diameter portion 8. The small diameter portion 8 is provided with one or more through holes 9 penetrating from the outside to the inside.

The jig 1 is a substrate for crystal growth 4 as described above.
With the substrate holder 6 set, the jig is inserted into the quartz ampoule 2 having an inner diameter slightly larger than the outer diameter of the jig 1. At this time, the melt material 5 together with the jig 1 is inserted into the quartz ampoule 2 so that the melt material is located in the notch recess 3. The constituent elements of the melt material 5 are Hg, Cd, and Te, and the composition ratio thereof is set according to the composition ratio of the multi-source semiconductor crystal to be manufactured.

Reference numeral 10 is a lid member for sealing the quartz ampoule 2, and the lid member 10 is integrally formed with the exhaust pipe 11 from quartz. After welding the lid member 10 to the end of the quartz ampoule 2, the quartz ampoule 2 is connected via the exhaust pipe 11.
A vacuum is drawn inside. After that, the quartz ampoule can be hermetically sealed by sealing the exhaust pipe 11 in the middle thereof, for example.

The process of liquid phase epitaxial crystal growth in this embodiment will be described with reference to FIG. First, the quartz ampoule 2 in which the crystal growth substrate 4 and the melt material 5 are enclosed together with the jig 1 is heated to a predetermined temperature higher than the crystal growth temperature in an electric furnace, and as shown in FIG. Then, the melt material 5 in the quartz ampoule 2 is melted to form a melt material 5 '. At this time, the angle of the quartz ampoule 2 is adjusted so that the exposed surface of the crystal growth substrate 4 faces upward on a horizontal plane.

Then, when the quartz ampoule 2 is rotated 180 °, the jig 1 is also rotated 180 ° together with the quartz ampoule 2. Since the liquid surface of the molten melt material 5'maintains a horizontal surface, the small-diameter portion 8 is buried in the molten melt material 5'by the rotation of the quartz ampoule 2, and the liquid surface of the molten melt material 5'is raised. The crystal growth substrate 4 facing downward contacts the molten melt material 5 '.

When the temperature in the furnace is lowered to a predetermined crystal growth temperature in this state, as shown in FIG. 2 (B), crystals of Hg _1-x Cd _x Te are formed on the surface of the crystal growth substrate 4. Layer 12 grows. At this time, the molten melt material 5'convects due to a temperature gradient or the like generated as the temperature inside the furnace lowers. The convection of the molten melt material occurs not only in the portion above the small diameter portion 8 but also in the small diameter portion. Since it is also performed on the outside and through the through holes 9, the effective volume of the molten melt material 5'is increased, and the non-uniformity of the solute concentration in the molten melt material is eliminated. As a result, the crystal layer 12 having a uniform thickness can be obtained on the crystal growth substrate 4, and the surface composition is uniform.

After that, when the crystal layer 12 having a predetermined thickness is formed, as shown in FIG. 2 (C), the quartz ampoule 2 is rotated again by 180 ° so that the molten melt material 5 ′ becomes a substrate for crystal growth. The crystal growth is stopped by making no contact with No. 4.

Finally, although not shown, the quartz ampoule 2 is slowly drawn out from the furnace, and the quartz ampoule 2 is pulled out.
And the crystal growth substrate 4 on which the crystal layer 12 is formed is removed from the substrate holder 6.

In this embodiment, one small through-hole 9 is provided in the small-diameter portion 8 in the axial direction of the quartz ampoule, but a plurality of smaller through-holes may be provided side by side in the axial direction of the quartz ampoule. .

Further, in this embodiment, all of the portions corresponding to the notched concave portions of the jig are small diameter portions, but the small diameter portions are partially formed at a plurality of places and the through holes are provided in the respective small diameter portions. Good.

When manufacturing an infrared detector using a multi-element semiconductor crystal containing Hg, Cd, and Te as constituent materials, a crystal having a sufficient thickness is required, so that the composition of the crystal surface is made uniform and uniform sensitivity characteristics are obtained. The present embodiment is extremely effective in realizing the above-mentioned detection element.

[0032]

As described above, according to the present invention,
It is possible to provide a multi-element semiconductor crystal having a uniform composition on the crystal surface.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a jig for liquid phase epitaxial crystal growth showing a preferred embodiment of the present invention.

FIG. 2 is an explanatory diagram of a process of liquid phase epitaxial crystal growth.

FIG. 3 is an explanatory diagram of a conventional technique.

FIG. 4 is an explanatory diagram of problems in the conventional technique.

[Explanation of symbols]

1 Jig for liquid phase epitaxial crystal growth 2 quartz ampoule 3 Notch recess 4 Crystal growth substrate 5 Melt material 5'Melted melt material 8 Small diameter part 9 through holes

Claims (3)

[Claims] 1. A notch recess (3) is formed by cutting out a part of the center of the outer periphery of the cylinder in the direction of the central axis of the cylinder, and a crystal growth substrate (4) is held in the notch recess. Melt material
A jig for enclosing the quartz ampoule (2) together with (5), in which at least a part of the part corresponding to the cutout recess (3) has an outer diameter smaller than that of the other part. A jig for liquid phase epitaxial crystal growth, characterized in that a through hole (9) penetrating from the crystal growth substrate (4) side to the quartz ampoule (2) side is provided in the small diameter portion (8). 2. A method for producing a multi-source semiconductor crystal using the jig for liquid phase epitaxial crystal growth according to claim 1, wherein the jig (1) is provided with the crystal growth substrate (4) and the melt. Vacuum encapsulation with the material (5) in the quartz ampoule (2), and horizontally supporting the quartz ampoule (2) so that the notch recess (3) faces downward, and heating the melt material.
(5) is melted, the quartz ampoule (2) is rotated by 180 °, the molten melt material (5 ′) is brought into contact with the crystal growth substrate (4) to grow crystals, and the quartz is melted. A step of rotating the ampoule (2) again by 180 ° so that the molten melt material (5 ') does not come into contact with the crystal growth substrate (4). 3. The crystal growth substrate (4) is made of CdTe, and the constituent elements of the melt material (5) are Hg, Cd, and T.
The method for producing a multi-source semiconductor crystal according to claim 2, wherein the method is e.