JPH0524962A - Method for producing compound semiconductor single crystal - Google Patents

Abstract

(57) [Summary] (Modified) [Structure] When a compound semiconductor single crystal is manufactured by the vertical Bridgman method or the vertical gradient freezing method, the seed crystal holding part of the single crystal growth container and the seed crystal are combined. A material for filling the gap is interposed. [Effect] The raw material melt does not flow into the gap between the seed crystal holding portion of the container for growing a single crystal and the seed crystal, and a single crystal with good crystallinity can be obtained in good yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a compound semiconductor single crystal using a seed crystal by a vertical Bridgman method or a vertical gradient freeze method, and more particularly to a method for holding a seed crystal.

[0002]

2. Description of the Related Art When growing a compound semiconductor single crystal by the vertical Bridgman method or the vertical gradient freeze method, a single crystal growth container as shown in FIG. 2 (a) or 2 (b) is generally used. ing.

In FIG. 2 (a), the bottom has a protrusion, and after the polycrystalline raw material is put into this container and melted, the container protrusion 6 is gradually temperature-graded so that it has the lowest temperature. It gradually cools and solidifies.

FIG. 2 (b) is provided with a portion 8 for holding the seed crystal 7. After the polycrystal raw material is put in this container and melted, a temperature gradient is applied so that the seed crystal has the lowest temperature. While gradually cooling from the seed crystal side, it solidifies.

In the case of the former method, it is necessary to selectively grow from a large number of crystal nuclei generated in the projecting portion of the container when solidification starts to finally form one crystal grain. Therefore, sufficient time must be taken for selective growth. In addition, the plane orientation of the selected crystal is not always the same. Furthermore, there is not always one crystal grain that finally remains, and there are cases in which some crystal grains may remain and there is the drawback that a single crystal cannot be obtained with good reproducibility.

The latter method uses a seed crystal in order to grow a crystal from a single nucleus from the beginning, does not have the above-mentioned drawbacks, and is a general method for growing a single crystal such as GaAs. However, in the case of CdTe single crystal, crystal defects are more likely to occur and the thermal conductivity is smaller than that of GaAs, so that
Even with this method, it was not possible to grow a product of sufficient quality.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention solves the above-mentioned problems, and is high in quality even with a compound semiconductor single crystal having a small thermal conductivity such that a crystal defect such as CdTe single crystal is likely to enter. The present invention provides a manufacturing method capable of obtaining the crystals of.

[0008]

The present invention relates to a method for growing a compound semiconductor single crystal using a seed crystal by the vertical Bridgman method or the vertical gradient freeze method, which is a seed crystal of a container for growing a single crystal. Manufacture of a compound semiconductor single crystal characterized by interposing a material for filling a gap between the holding portion and the seed crystal so that the compound semiconductor melt does not flow into the gap of the seed crystal holding portion during single crystal growth. This is a method, and a crystal defect such as a CdTe single crystal is easily introduced, and a high quality crystal can be obtained even with a compound semiconductor single crystal having a small thermal conductivity.

As a material for filling the gap, finely crushed compound semiconductor crystal powder may be used, or a graphite seed crystal holder processed so as not to form a gap with the side surface of the seed crystal may be used.

The present inventors have considered that the cause of the above-mentioned problems lies in the gap between the seed crystal holding portion of the single crystal growth container and the seed crystal. That is, if there is a gap between the seed crystal holding portion of the single crystal growth container and the seed crystal, when melting the polycrystalline raw material, the polycrystalline raw material melt flows into the gap and rapidly solidifies,
Since the crystallinity of the seed crystal is adversely affected and the crystal is grown from this portion where the crystallinity is deteriorated, the poor crystallinity is inherited and the crystallinity of the entire single crystal is deteriorated.

Moreover, the gap between the seed crystal holding portion of the single crystal growth container and the seed crystal is affected by the accuracy of the shape of the container, and the single crystal growth container made of quartz or PBN is machined. Because it was not possible, the precision of the shape was not very good, and the gap could not be eliminated.

Therefore, the present inventors fill the gap between the seed crystal holding part and the seed crystal of the single crystal growing container without directly holding the seed crystal in the seed crystal holding part of the single crystal growing container. I came up with the idea of interposing materials.

As a material for filling the gap between the seed crystal holding portion of the container for growing a single crystal and the seed crystal, a polycrystal raw material melt is used when the polycrystal raw material is melted without contaminating the compound semiconductor single crystal. In order not to flow into the gap, a finely crushed compound semiconductor single crystal powder or a graphite seed crystal holder processed so as not to form a gap with the side surface of the seed crystal is used.

When finely crushed compound semiconductor single crystal powder is used as the material for filling the gap between the seed crystal holding portion of the container for growing a single crystal and the seed crystal, the temperature is raised to melt the polycrystalline raw material. Since the compound semiconductor crystal powder is sintered in the process of forming and has no gap, the polycrystalline raw material melt does not flow into the gap. Further, it was considered that other crystal grains were generated from the compound semiconductor crystal powder and polycrystallized, but the crystal grains generated from the compound semiconductor crystal powder disappeared immediately after seeding, and there was no problem.

Next, as a material for filling the gap between the seed crystal holding portion of the container for growing a single crystal and the seed crystal, a graphite seed crystal holder processed so as not to form a gap with the side surface of the seed crystal is used. When used, graphite is easy to perform precision processing, and the gap between the graphite seed crystal holder and the seed crystal and between the graphite seed crystal holder and the seed crystal holding portion of the single crystal growth container can be made sufficiently small. Therefore, the polycrystalline raw material melt does not flow into the gap. Further, it was considered that other crystal grains were generated from the gap between the graphite seed crystal holder-or the graphite seed crystal holder-and the seed crystal holding portion of the single crystal growth container to be polycrystallized, No nucleation occurred from the graphite seed crystal holder, and the crystal grains generated from the gap between the seed crystal holder of the single crystal growth container disappeared immediately after seeding, and there was no problem.

[0016]

EXAMPLE 1 As shown in FIG. 1, a seed crystal holding portion 2 of a PBN crucible 1 having an inner diameter of 8 mmΦ was washed with a seed crystal 3 of a cylindrical CdTe single crystal having a plane parallel to the (111) plane after etching, CdTe crystal powder 4 was put around it. Subsequently, the CdTe polycrystalline raw material 5 was put in the crucible straight body portion having an inner diameter of 80 mmΦ, the crucible was put in a quartz ampoule, and the degree of vacuum was 1
It was sealed at 0 ^-6 torr. This quartz ampoule is loaded into a crystal growth furnace, heated to a temperature close to the melting point of CdTe, and a temperature gradient of 2 to 10 ° C./cm is applied in the vertical direction of the ampoule to further raise the temperature so that the middle of the seed crystal becomes a melt. After homogenizing for 50 hours, the crucible tip was gradually cooled to grow a crystal. By this method, a crystal having a desired plane orientation and having good crystallinity as a whole can be obtained from the seed crystal without deteriorating the crystallinity, and a good quality wafer can be obtained from almost the entire area.

[0017]

EXAMPLE 2 A graphite seed crystal holder having an inner diameter of 6 mmΦ was loaded with a cylindrical CdTe single crystal seed crystal having a surface parallel to the (111) plane after etching and cleaning, and then having an inner diameter of 8 mmΦ.
The PBN crucible was placed in a seed crystal holding part. After that, the crystal was grown in the same manner as in Example 1. By this method, a crystal having a desired plane orientation and having good crystallinity as a whole can be obtained from the seed crystal without deteriorating the crystallinity, and a good quality wafer can be obtained from almost the entire area.

Although the examples have been described with respect to CdTe single crystals, it goes without saying that they can also be used in the production of compound semiconductor single crystals of groups 2-6 or 3-5 other than CdTe.

[0019]

According to the present invention, when the polycrystalline raw material is melted, the polycrystalline raw material melt does not flow into the gap, so that the crystallinity does not deteriorate from the seed crystal portion.
The crystallinity of the entire grown crystal was improved, and a compound semiconductor single crystal having a desired plane orientation could be obtained in good yield.

[Brief description of drawings]

FIG. 1 is a diagram showing one embodiment of a seed crystal holding method according to the present invention.

FIG. 2 is a view showing a conventional single crystal growth container.

Claims (3)

[Claims] 1. A method for growing a compound semiconductor single crystal using a seed crystal by the vertical Bridgman method or the vertical gradient freeze method, wherein a gap is provided between the seed crystal holding part of the single crystal growth container and the seed crystal. A method of manufacturing a compound semiconductor single crystal, characterized in that a compound semiconductor melt is prevented from flowing into a gap of a seed crystal holding portion during the growth of the single crystal by interposing a filling material. 2. A method for producing a compound semiconductor single crystal, wherein the material for filling the gap according to claim 1 is finely crushed compound semiconductor crystal powder. 3. A method for producing a compound semiconductor single crystal, wherein the material for filling the gap is a graphite seed crystal holder processed so as not to form a gap with the side surface of the seed crystal.