JP2733898B2 - Method for manufacturing compound semiconductor single crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal growing technique, particularly a liquid-sealed chiroporous method (hereinafter referred to as an LEK method).
The present invention relates to a compound semiconductor single crystal growth apparatus to which is applied.

[0002]

2. Description of the Related Art Generally, GaP, GaAs, InP, C
Since III-V and II-VI compound semiconductors such as dTe have a high vapor pressure near the melting point, they are formed by a liquid sealing method in which the raw material melt is covered with a liquid sealing agent layer made of B ₂ O ₃ or the like. Single crystal growth is taking place. At present, as the liquid sealing method, a liquid sealing Czochralski method (LEC method), an LEK method, and the like are known. The LEC method is a method in which the seed crystal is pulled up as the crystal grows. The crystal orientation can be controlled by seeding, and high-purity crystals can be easily obtained. And the temperature gradient near the solid-liquid interface during crystal growth is large, so that thermal stress is increased and dislocation defects are increased.

[0003] On the other hand, in the LEK method, since the crystal is grown in a refractory crucible without pulling the crystal, the diameter of the grown crystal depends on the inner diameter of the crucible. Therefore, the diameter can be easily controlled, and the temperature gradient in the melt during crystal growth is several degrees centigrade / cm, which is one digit smaller than that of the LEC method.
It has the advantages of low thermal stress and few dislocation defects.

The LEK method is performed using an apparatus as shown in FIG. 5, for example. The crystal growth apparatus shown in FIG.
A cylindrical heater 2 is disposed in a closed high-pressure vessel 1, and a fire-resistant crucible 3 is provided at the center of the heater 2.
Is arranged. The crucible 3 is supported by a crucible receiver 4. Furthermore, this crucible holder 4
Is rotatably supported by a support shaft 5 fixed to its lower end. And, in this crucible 3, GaAs
Raw material melt 6 are placed equal, the upper surface of the raw material melt 6 is covered with a liquid sealant layer 7 of B ₂ O ₃ and the like. On the other hand, from above the crucible 3, a crystal pulling shaft 8 is suspended vertically and rotatably in the high-pressure vessel 1, and the seed pulling 9 is held by the crystal pulling shaft 8. 6 can be brought into contact with the surface.

In the LEK method, a seed crystal 9 is first immersed in a raw material melt 6 by a crystal pulling shaft 8 as shown in FIG. Next, in order to prevent non-uniform crystal growth, the convection of the raw material melt is controlled while rotating the crucible 3 and the pulling shaft 8, and a single crystal is grown without pulling. Single crystal 10, after completion of the growth, and so as to cool by pulling the liquid sealant layer 7 in the upper high-pressure inert gas 11 to separate the single crystal 10 from the raw material melt 6.

In the crystal growth process of the LEK method, since the crystal grows following the crucible, the horizontal cross-sectional shape of the crystal growing in the crucible is the largest circle inscribed in the crucible about the axis of the crystal pulling axis. Becomes Compared to the LEC method, there is a problem that it is difficult to efficiently produce a relatively long single crystal because the seed crystal is not pulled.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and as a result of intensive studies, particularly focusing on the slip resistance between a grown single crystal and a crucible,
The present invention has been found that a relatively long compound semiconductor single crystal can be easily obtained by controlling the gap between the crucible and the single crystal.

[0008]

Means for Solving the Problems That is, the present invention provides a high-pressure vessel, in a crucible placed under an inert atmosphere, to melt the raw material and a liquid sealing agent, then a seed crystal to the raw material melt In the method of manufacturing a compound semiconductor single crystal in which the heating temperature is controlled while rotating the crucible and the seed crystal while being immersed to grow a single product having a predetermined diameter, the same horizontal plane from the center of rotation of the seed crystal to the inner wall of the crucible is provided. Growing a single product so that the ratio of the shortest distance to the longest distance (shortest distance / longest distance) becomes 0.75 or more and 0.99 or less in the above method. is there.

In the LEK method, since the crystal grows following the crucible, the horizontal cross-sectional shape of the crystal growing in the crucible is the largest circle inscribed in the crucible with the center of the crystal pulling axis as the center. However, the crucible and the liquid sealant thickness fraction smaller remaining between the crystals. In a conventional crucible having a circular horizontal cross-sectional shape as shown in FIG. 4, since the horizontal cross-sectional shape of the grown crystal and the crucible cross-sectional shape are almost the same circle, the gap between the grown crystal and the crucible is very small. Then, the gap is filled with the liquid sealing material, and the sliding resistance between the grown crystal and the crucible becomes extremely large. Therefore, it is difficult to keep rotating the crucible and the pulling shaft separately, so that it is difficult to control the convection of the raw material melt suitable for crystal growth, and it is difficult to obtain a large single crystal.

In the present invention, the sliding resistance between the compound semiconductor single crystal and the crucible is reduced by providing a gap between the compound semiconductor single crystal and the crucible by providing a gap between the compound semiconductor single crystal and the crucible. A large single crystal can be obtained efficiently. In the present invention, the size of the gap is such that the ratio of the shortest distance to the inner wall of the crucible from the center of rotation of the single product to the inner wall of the crucible (shortest distance / longest distance) is 0.75 or more.
The range is 99 or less. Shortest distance to inner wall of crucible /
When the longest distance ratio is 0.99 or more, the gap between the compound semiconductor single product and the crucible is not sufficient, the slip resistance between the compound semiconductor single crystal and the crucible increases, and it becomes difficult to obtain a single crystal. On the other hand, when the shortest distance / longest distance ratio to the inner wall of the crucible is 0.75 or less, the diameter of a single crystal that can be grown depends on the shortest distance between the rotation center of the single crystal and the crucible. The diameter becomes small, which is not preferable. Further, since the crucible and thickness distribution of the liquid sealing agent of the gap between the growing single crystal is increased, the horizontal temperature fluctuations of the growing single crystal is increased, the temperature control of the system is deteriorated disadvantages Also have. More preferably, the ratio of the shortest distance from the rotation center of the single crystal to the inner wall of the crucible and the longest distance (shortest distance / longest distance) is 0.94 or more and 0.98 or less.

Specific means for providing a gap satisfying the above conditions between the single crystal and the crucible are as follows: (1) The horizontal cross-sectional shape of the crucible used is such that the slip resistance between the single crystal and the crucible is reduced. Use things. For example, oval, oval, star, polygon, rounded corners, round / oval / oval cutouts, irregular shapes, etc. elliptical movement of the sealing agent becomes smooth is preferable. (2) The position of the seed crystal is shifted from the center axis of the crucible. And the like.

By the above means, a relatively large gap is formed between the crystal and the inner wall of the crucible, so that the sliding resistance between the crystal and the crucible can be reduced, and the convection of the raw material melt can be easily controlled. In addition, the above object of efficiently obtaining a large single crystal can be achieved. In addition, slippage between the crucible and the crucible receiver can be prevented.

[0013]

Embodiment 1 (Embodiment 1) As shown in FIG.
3 was used, and an elliptical crucible (short diameter 65 mm, long diameter 67 mm) shown in FIG. 1 was used. First, weighed _B 2 _{O 3} GaAs polycrystal 3.8kg and (raw material melt height 200 mm) as the liquid sealant <br/> to a thickness of 25 mm, placed in a pBN crucible, The inside of the furnace was heated to 1250 ° C. or higher by heating with the heater 2, and GaAs and B ₂
The O ₃ was melted. At this time, in order to prevent the volatilization of As, argon gas was introduced from the gas introduction pipe 12, and the inside of the high-pressure vessel 1 was set to 30 atm. Next, after adjusting the surface temperature of the GaAs melt to a temperature slightly higher than the melting point of GaAs,
The crystal pulling shaft 8 was lowered, the (100) plane seed crystal 9 was seeded into the raw material melt 6, and the crystal was grown for 200 hours while cooling the melt at a rate of 1 ° C./hr. At this time, the crystal pulling shaft 8 was rotated at 30 rpm, and the crucible shaft 5 was rotated at 30 rpm in the opposite direction. After a lapse of 200 hours from the start of the growth, the axial torque at the time when the single crystal 10 grew almost to the bottom of the crucible was 1.0 kg · m, which was 1/4 of that when a circular crucible was used. The grown crystals were all single crystals.

Example 2 A crucible having a shape in which both ends of a circle were cut off as shown in FIG. 2 (distance between parallel portions: 65 mm, diameter: 67 mm) was used, and all other experimental conditions were used (Example 1). GaAs crystals were grown under the same conditions as described above. After a lapse of 200 hours from the start of the growth, the axial torque at the time when the single crystal 10 grew almost to the bottom of the crucible was 0.40 kg · m, which was 1/10 of that when a circular crucible was used. The grown crystals were all single crystals. It should be noted that a crucible having a shape as shown in FIG. 3 has the same effect.

Comparative Example 1 A circular shape (φ65 shown in FIG. 4)
GaAs crystals were grown under the same conditions as in Example 1 except that a crucible (mm) was used. After about 200 hours, the single crystal 10
The shaft torque at the time when grew almost to the bottom of the crucible was 4.
It was 13 kg · m. The grown crystal was polycrystallized in the middle of the growth part.

[0016]

As described above, the present invention reduces the slip resistance between a crystal and a crucible by forming a gap between the single crystal and the crucible, and controls the convection of the raw material melt. And the above object of easily obtaining a large single crystal can be achieved.

[Brief description of the drawings]

FIG. 1 is shown in (Example 1) of the present invention.

FIG. 6 is an explanatory view of a section taken along line AA of FIG.

FIG. 2

FIG. 3 shows (Example 2) of the present invention.

FIG. 6 is an explanatory view of a section taken along line AA of FIG.

FIG. 4 shows Comparative Example 1

FIG. 6 is an explanatory view of a section taken along line AA of FIG.

FIG. 5 shows a basic configuration of an apparatus used in the present invention.

FIG. 6 shows a basic device configuration in (Example 1), (Example 2), and (Comparative Example 1).

[Explanation of symbols]

1; high-pressure container 2; heater 3; crucible 4; crucible supporting 5; support shaft 6; raw material melt 7; liquid sealant layer 8; crystal pulling shaft 9; seed crystal 10; single crystal 11; high pressure inert gas 12 ; Gas inlet pipe 13; torque meter

Claims (1)

(57) [Claims] 1. A high-pressure vessel, in a crucible placed under an inert atmosphere, to melt the raw material and a liquid sealing agent, then each rotating the crucible and the seed crystal by immersing the seed crystal to the raw material melt In the method of manufacturing a compound semiconductor single crystal in which the heating temperature is controlled while growing, a single crystal having a predetermined diameter is grown,
Ratio of the shortest distance to the longest distance on the same horizontal plane from the center of rotation of the seed crystal to the inner wall of the crucible (shortest distance / longest distance)
Wherein the single crystal is grown so as to be 0.75 or more and 0.99 or less.