JPH08283094A - Production of single crystal and device therefor - Google Patents

Abstract

PURPOSE: To obtain a method for producing a large-sized semiconductor single crystal having high quality with good reproducibility at a high yield. CONSTITUTION: A gap 3 is formed between the circumference at the front end of a heat sink 2 installed in the crystal growth section in a hermetic vessel 1 and the inside wall of this hermetic vessel 1 and growth of the single crystal is executed by depositing the raw material vapor of the crystal on a seed crystal held at the heat sink 2 and maintaining the state that the growing single crystal does not come into contact with the wall surface of the vessel in the method for producing the single crystal by a vapor growth method in the hermetic vessel 1. Consequently, the growth of the semiconductor single crystal without contact with the wall surfaces of the vessel is made possible and the good- quality single crystal of the compd. semiconductor having the good uniformity of the compsn distribution and low dislocation density is produced at the high 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 producing a semiconductor single crystal and an apparatus therefor, and more particularly to a method for producing a large-sized high quality semiconductor single crystal with few crystal defects with good reproducibility and a single crystal used therefor. The present invention relates to a manufacturing device.

[0002]

2. Description of the Related Art Since compound semiconductors such as PbTe, GaSe, and GaAs have a lower mechanical strength than Si, they are easily affected by thermal and mechanical stress during crystal growth, and have a high quality single crystal with few defects. It is extremely difficult to make crystals.
As a crystal growth method that solves this problem, the thermal stress at the crystal growth interface is reduced by decreasing the temperature gradient, and the crystal is grown so that it does not touch the wall surface of the container. A method for suppressing stress has been proposed (for example, Japanese Patent Publication No. 57-54480). However, since this method does not use a jig for controlling crystal nucleation or a seed crystal, a large number of small crystal nuclei are generated and the probability that only one single crystal grows is very small. There was a problem.

[0003]

As described above, in the conventional single crystal growth method, since neither a jig for controlling the crystal nucleus generation nor a seed crystal is used, one single crystal is grown large. There is a problem that the probability is very small and a polycrystal is easily formed.

An object of the present invention is to solve the problem that the yield of single crystallization is small in the prior art described above, and to manufacture a large-sized and high-quality semiconductor single crystal with high reproducibility and high yield. It is to provide a method and an apparatus for producing a single crystal used for the method.

[0005]

In order to achieve the above-mentioned object of the present invention, the present invention has a constitution as set forth in the claims. That is, according to the present invention, as described in claim 1, in a method for producing a single crystal by a vapor phase growth method in a closed container, around a tip of a heat sink installed in a crystal growth part in the closed container, A state in which a gap is formed between the closed container and the inner wall of the heat sink, and the raw material vapor of the crystal is deposited on the tip surface of the heat sink or on the seed crystal held by the heat sink so that the growing single crystal does not touch the wall surface of the container. Is held to grow a single crystal. Then, as an apparatus for growing a single crystal according to claim 1, the present invention is, as described in claim 2, an apparatus for producing a single crystal by a vapor phase growth method in a closed container, wherein: The heat sink is installed in the crystal growth portion, and a gap is provided between the periphery of the heat sink tip and the inner wall of the closed container. Also,
According to the present invention, as described in claim 3, in claim 2,
The heat sink for growing the single crystal in the hermetic container has a dent on the tip surface. Further, as described in claim 4, the present invention has the structure according to claim 2, wherein a seed crystal for growing a single crystal is provided at the tip of the heat sink. Further, according to a fifth aspect of the present invention, in the second aspect, the heat sink has a structure made of a seed crystal for growing a single crystal.

[0006]

According to the present invention, as described in claim 1, in a method for producing a single crystal by a vapor phase growth method in a closed container, a heat sink is provided with a crystal nucleation part or a seed crystal holding part, and a heat sink and an inner wall of the container are provided. Since a gap is provided between the two, the heat of crystallization generated along with the crystal growth is carried away by the heat sink, so that the temperature rise of the crystal during growth can be suppressed, the composition distribution is uniform, and A single crystal such as a high-quality compound semiconductor with a low dislocation density can be produced with a high yield without the crystal being subjected to mechanical stress from the wall surface of the container. Further, as described in claim 2, the present invention is an apparatus for carrying out the method for producing a single crystal by the vapor phase growth method according to claim 1, which is a heat sink tip installed in a crystal growth part in a closed container. A gap is formed between the surrounding area and the inner wall of the closed container, so that the single crystal growing from the crystal nucleation part of the heat sink or the seed crystal holding part does not come into contact with the inner wall of the container. Generation of stress can be suppressed, and a semiconductor single crystal with a low dislocation density can be obtained. Further, according to the present invention, as in claim 3, in claim 2, the heat sink for growing the single crystal is formed with a depression on the front end surface thereof, and the temperature of the depression is higher than that of the other portions. Is low and the crystal nuclei are easily generated, the probability of single crystal growth is high, and a semiconductor single crystal can be produced with good reproducibility. Further, according to the present invention, as described in claim 4, since the seed crystal for growing the single crystal is provided at the tip of the heat sink in the second aspect, the probability of the single crystal growth increases and the reproduction is improved. A single crystal of a semiconductor can be manufactured with good properties. Further, according to the present invention, as in claim 5, in claim 2, the heat sink is constituted by a seed crystal for growing a single crystal, so that the single crystal can be efficiently grown, and further, the single crystal can be grown. The growth probability is increased, and a semiconductor single crystal can be manufactured with good reproducibility.

[0007]

Embodiments of the present invention will be described below in more detail with reference to the drawings. Example 1 FIG. 1 (a) is a schematic view showing an example of the cross-sectional structure of the closed container of the single crystal production apparatus used in this example, and FIG. 1 (b) shows the temperature distribution in the closed container. It is a graph shown. In the figure, a quartz heat sink 2 is inserted into a quartz container 1 and pressed against the container end surface 1 a of the quartz container 1. The tip of the heat sink 2 is thin, and a gap 3 is formed between the heat sink 2 and the inner wall surface of the quartz container 1. A crystal nucleus generating recess 4 is formed in the center of the tip surface of the heat sink 2. Next, the previously synthesized Pb _0.8 Sn _0.2 Te polycrystalline raw material 5 was inserted into the quartz container 1, and the quartz container was evacuated so that the pressure was 1 × 10 to ⁵ Torr (mmHg) or less. By welding the container end surface 1b of No. 1 to the heat sink 2 and Pb _0.8
The Sn _0.2 Te polycrystalline raw material 5 and the quartz container 1 are vacuum-sealed. The quartz container 1 for producing a single crystal thus produced is mounted in an electric furnace and heated so that the temperature distribution shown in FIG. In this example, polycrystalline raw material 5
Part is heated to about 880 ℃, 2 parts of heat sink is 825 ℃
The temperature difference is controlled so that a temperature difference of about 55 ° C. is formed between the polycrystalline raw material portion and the heat sink portion. In the polycrystalline raw material part, PbTe molecules and SnTe molecules are sublimated into vapors, and the raw material vapors are transported to the low temperature heat sink portion due to the difference in equilibrium vapor pressure caused by the above temperature difference, and used for generating crystal nuclei of the heat sink 2. It is deposited on the surface having the depression 4, and the growth of the single crystal proceeds. Here, the heat of crystallization generated with the growth of the single crystal is carried away by the heat sink 2, so that the temperature rise of the single crystal during growth is suppressed. Since the liquidus temperature of Pb _0.8 Sn _0.2 Te is about 905 ° C., the polycrystalline raw material 5 is not melted by heating at about 880 ° C. The method according to the present example is called a physical vapor transport method because the polycrystalline raw material is evaporated without thermal decomposition, is transported to a low temperature part to grow a single crystal, and is not accompanied by a chemical change. There is. 2 and 3 are schematic diagrams showing a single crystal growth process, FIG. 2 shows an initial stage of single crystal growth, and FIG. 3 shows a final stage of single crystal growth. The raw material vapor transported to the heat sink 2 adheres to the tip of the heat sink 2 and the end of the gap 3 to start crystal growth (FIG. 2). Since a small crystal nucleus forming recess 4 is formed on the tip surface of the heat sink 2, one crystal nucleus 6 is formed in the recess 4 and gradually grows into a large single crystal 7. (Figure 3). The growth of a single crystal starts from the crystal nucleus generation recess 4 on the tip surface of the heat sink 2 because the temperature of the recess 4 of the heat sink 2 is lower than the temperature of the tip surface due to the temperature gradient in the quartz container 1. Is easily generated. Then, the raw material vapor transported to a place other than the tip surface of the heat sink 2 enters the gap 3 and is trapped at the end of the gap to become a deposit 8. Therefore, the single crystal has a columnar shape with the tip surface of the heat sink 2 as the bottom surface. , And does not contact the inner wall surface of the quartz container 1. Therefore, a high quality single crystal with a low dislocation density can be grown without the single crystal receiving mechanical stress from the wall surface of the container. Under the temperature distribution shown in FIG. 1B, a single crystal having a length of about 20 mm could be produced over about 5 days. The obtained single crystal was excellent in uniformity of composition distribution (1% or less due to fluctuation of Pb / Sn ratio) and had a low dislocation density of about 10 cm to ^{2 on} average. This value is almost equal to or lower than that of the single crystal produced by the method described in Japanese Patent Publication No. 57-54480.

<Embodiment 2> FIG. 4 is a schematic view showing the structure of a single crystal production container exemplified in this embodiment. In this embodiment, a boron nitride heat sink 9 having a thermal conductivity higher than that of quartz is used, and the tip of the heat sink 9 is
Instead of providing a recess for crystal nucleation, Pb _0.8 Sn _0.2
The structure is provided with a BaF ₂ seed crystal 10 having a lattice constant close to that of Te. In this embodiment, a single crystal that inherits the orientation of the BaF ₂ single crystal can be grown, and the growth orientation of the single crystal can be controlled in any direction.

Example 3 FIG. 5 is a schematic view showing the structure of a single crystal production container exemplified in this example. In this embodiment, the protrusion 11 is formed on the inner wall surface of one end of the quartz container 1.
Is formed, and a heat sink (BaF) of uniform thickness is formed.
_{Even if (2} seed crystals) 12 is used, the gap 3 is formed. In the present embodiment, BaF
_{2 The} seed crystal 12 is long, and this seed crystal also serves as a heat sink.

<Embodiment 4> FIG. 6A is a schematic view showing the structure of a single crystal production container exemplified in this embodiment, and FIG. 6B is a temperature distribution in the quartz container 1. It is a graph which shows. In this example, a single crystal is manufactured by a chemical vapor deposition method using iodine as a transport medium. A raw material Ga13, a raw material Se14, and iodine 15, which is a transport medium, were vacuum-sealed in the raw material portion. As shown in FIG. 6B, the temperature of the raw material part was set to 870 ° C., the part of the heat sink 2 was heated to 840 ° C., and a temperature difference of 30 ° C. was provided between them. Since the vapor pressure of Se is high, Se becomes gaseous in the raw material portion and evaporates, and is transported to the heat sink portion.
On the other hand, Ga reacts with iodine (I ₂ ) to become GaI or GaI ₃ gas, which is transported to the heat sink,
There, it reacts with Se vapor to produce a GaSe solid,
aSe is deposited on the tip surface of the heat sink. This reaction
By repeating the deposition process, a large single crystal of GaSe is grown.

[0011]

As described above, according to the method for producing a single crystal of the present invention, various semiconductor single crystals can be grown with good reproducibility without contact with the wall surface of the container, and the composition distribution can be made uniform. And a single crystal such as a good quality compound semiconductor having a low dislocation density can be manufactured with a high yield. Therefore, PbTe, Pb _0.8 Sn _0.2 Te, GaSe,
It is extremely effective for growing a crystal having a low dislocation density such as a compound semiconductor in which dislocation is likely to occur in a soft semiconductor crystal such as GaAs or CdTe.

[Brief description of drawings]

FIG. 1 is a schematic view showing a structure of a single crystal production container (a) illustrated in Example 1 of the present invention and a graph showing a temperature distribution in the container (b).

FIG. 2 is a schematic diagram showing an initial stage of single crystal growth exemplified in Example 1 of the present invention.

FIG. 3 is a schematic diagram showing a final stage of single crystal growth exemplified in Example 1 of the present invention.

FIG. 4 is a schematic diagram showing the structure of a single crystal production container exemplified in Example 2 of the present invention.

FIG. 5 is a schematic diagram showing the structure of the single crystal production container illustrated in Example 3 of the present invention.

6A and 6B are a schematic view showing a structure of a single crystal production container (a) and a graph showing a temperature distribution in the container (b) illustrated in Example 4 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Quartz container 1a ... Container end surface 1b ... Container end surface 2 ... Heat sink 3 ... Gap 4 ... Cavity for crystal nucleation 5 ... Pb _0.8 Sn _0.2 Te polycrystalline raw material 5a ... Polycrystalline raw material residue 6 ... Crystal nucleus 7 ... Single crystal 8 ... Deposit 9 ... Boron nitride heat sink 10 ... BaF ₂ seed crystal 11 ... Protrusion 12 ... BaF ₂ seed crystal (heat sink) 13 ... Raw material Ga 14 ... Raw material Se 15 ... Iodine

Claims (5)

[Claims] 1. A method for producing a single crystal by a vapor phase growth method in a closed container, wherein a single crystal is formed between a tip of a heat sink installed at a crystal growth part in the closed container and an inner wall of the closed container. A gap is formed, and the source vapor of the crystal is deposited on the tip surface of the heat sink or on the seed crystal held by the heat sink, and the growing single crystal is kept in contact with the wall surface of the container to grow the single crystal. A method for manufacturing a single crystal, which is characterized by performing. 2. An apparatus for producing a single crystal by a vapor phase growth method in a closed container, comprising: a heat sink installed in a crystal growth part in the closed container; and a heat sink around the tip of the heat sink and an inner wall of the closed container. An apparatus for producing a single crystal having a gap. 3. The apparatus for producing a single crystal according to claim 2, wherein the heat sink for growing the single crystal has a recess formed in the front end surface thereof. 4. The apparatus for producing a single crystal according to claim 2, wherein a seed crystal for growing the single crystal is provided at the tip of the heat sink. 5. The apparatus for producing a single crystal according to claim 2, wherein the heat sink is composed of a seed crystal for growing the single crystal.