JPH02167888A - Production of crystal of compound semiconductor of iii-v - Google Patents

Abstract

PURPOSE:To obtain high-quality uniform single crystal of compound semiconductor of III-V in liquid encapsulated Czochralski method by moving a crucible and seed crystal to an upper low-temperature zone in a state of the seed crystal being in contact with melt of compound semiconductor of III-V and coagulating melt to form single crystal. CONSTITUTION:The top of melt 11 of compound semiconductor of III-V in a crucible 3 whose surroundings are covered with an inert gas atmosphere under $1atm is coated with the melt 11 and an inert liquid encapsulating agent 10 (e.g. B2O3). Then seed crystal 9 of compound semiconductor of III-V is brought into contact with the melt 11 of semiconductor. Then in this state, the crucible 3 and seed crystal 9 are moved to an upper low-temperature zone 5, the melt 11 in contact with the seed crystal 9 in the crucible 3 is coagulated and single crystal of compound semiconductor of III-V is formed to prevent occurrence of polycrystal and twin and to obtain the single crystal of compound semiconductor (e.g. GaAs) of III-V.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a single crystal of a lI[-Vl compound semiconductor using a crucible.

[Conventional technology]

Conventionally, the liquid-sealed Czochralski method (
These methods include the LEC method), the horizontal boat method (HB method), and the 4-degree gradual cooling method (VGF method).

For example, in the EC method, raw materials for the desired single crystal and liquid sealant are filled in a vertical crucible with a heater around it, and the crucible is placed in a high-pressure container and the inside of the container is kept under high pressure and inert. Replacement with gas (7. Heat the crucible with a heater, melt the raw materials, etc., cover the surface of the raw material melt with a liquid sealant such as 8201, and contact the surface of the raw material melt with a single crystal seed crystal. The target single crystal is produced by growing a single crystal around a seed crystal and pulling it up.

Further, the VGF method is a method in which a crucible containing raw materials for the target single crystal is heated to melt the raw materials, and then the heating temperature is gradually lowered to solidify the raw material melt to produce the target single crystal. At this time, instead of gradually lowering the heating temperature, there is also a method called the VB method in which the crucible is lowered in a furnace with a temperature gradient at a lower temperature to solidify the raw material melt.

In addition, in the HB method, a temperature gradient is provided in the horizontal direction, and the VG
This is the method using the F method in the horizontal direction.

[Problem to be solved by the invention]

However, when manufacturing an m-v group compound semiconductor single crystal using such a method, there are the following problems.

That is, in the LEC method, since the temperature gradient changes during crystal growth, the shape of the growth interface changes, resulting in an increase in polycrystals and twin crystals. Furthermore, since the crystals pulled from the crucible are exposed above B = O, which is used to seal the liquid, arsenic, etc., which have a high vapor pressure, evaporates, causing the generation of polycrystals.

Considering the difficulty in producing a single crystal, if the diameter is increased, it becomes difficult to control the diameter, which poses a problem in achieving high quality crystals.

Furthermore, in the H B method, a quartz boat is used to obtain the GaAs single crystal, so Si is mixed into the single crystal.
It was not possible to achieve high purity of the hayashi crystal.

Furthermore, in the VGF method and VB method, since the seed crystal is placed at the bottom of the crucible, it is impossible to observe the initial solidification phase at all after the seed crystal and the semiconductor melt come into contact, so it is difficult to observe whether a single crystal is growing. It was not possible to determine whether or not.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has been developed to provide high quality and uniform I.
A method for producing single crystal IV compound semiconductors has been developed.

That is, in the method of the present invention, the upper surface of the ■-V group compound semiconductor melt in a crucible surrounded by an inert gas atmosphere of 1 atm or more is exposed to the melt and an inert nonvolatile liquid sealant melt. The seed crystal of the ■-V group compound semiconductor is brought into contact with the semiconductor melt, the crucible and the seed crystal are moved to an upper low temperature region, and the melt in the crucible in contact with the seed crystal is solidified. (2) This method is characterized by obtaining a single crystal of a group V compound semiconductor.

The temperature of the melt zone in which the ■-V group compound semiconductor is in the melt state is set to 10° below the melting point of the ■-V group compound semiconductor.
It is effective to set the temperature to 0° C. higher or lower, and to set the temperature in the low temperature range to a temperature lower than or equal to the above melting point and 300° C. lower than the melting point.

Furthermore, as a material for the crucible containing the ■-V group compound semiconductor melt, PBN (Pyrolitic Boron) is used.
It is effective to use Ar, N, CO2, CH4, or a mixture thereof as an inert gas.

In addition, when moving the crucible and seed crystal to an upper low-temperature area to solidify the ■-■ group compound semiconductor, the pulling speed of the seed crystal is set higher than the moving speed of the crucible so that the speed difference is 20 mm/hr or less. It is preferable to move the seed crystal and the crucible upward while rotating in the same direction, or to apply a magnetic field to the melt during solidification of the Japanese-■ group compound semiconductor F\1 liquid.

[Effect]

The crucible and the seed crystal in contact with the III-V compound semiconductor melt in the crucible are moved from the melt zone to the two lower temperature regions with a slightly larger speed difference for the seed crystal. This is because the melt solidifies at the boundary between the two temperature ranges, so the crystals always grow under the same temperature gradient, making it possible to obtain high-quality, uniform crystals without forming polycrystals. It is from. Furthermore, the compressive stress in the crucible can be reduced due to the speed difference.

〔Example〕

Next, examples of the present invention will be described.

As shown in Fig. 1, a PBN crucible (3) is attached to the upper end of a crucible shaft (2) that can be moved up and down and rotated by a precision motor that penetrates the lower surface of a stainless steel high-pressure container (1).
A melt zone heater (4) and a low temperature zone heater (5) are arranged above the crucible (3), and a seed crystal that penetrates the upper surface of the high pressure container (5) and can move up and down and rotate freely. A single crystal manufacturing apparatus provided with a shaft (6) was manufactured. In addition(
7) indicates a heat insulating material, and 8) indicates a viewing rod for observing the inside of the crucible.

Approximately 4k is stored in the crucible (3) in the high-pressure container (1) of the above device.
20g of GaAs polycrystalline raw material and liquid sealant
After putting 0g of B = Oj and attaching a GaAs single crystal seed crystal <9) to the lower end of the seed crystal shaft (6), the inside of the high-pressure container (1) was evacuated and Ar was introduced to inside the container. 2
The pressure was increased to 0 kg/-, and both heaters (4) and (5) were heated to set the d degree profile shown in FIG. Note that as the above-mentioned raw material, a mixture of Ga and As at a constant molar ratio, with a total weight of about 4 kg, may be used.

Next, after melting the raw material and B t 03, the seed crystals are
The 0j melt (lO) was brought into contact with the raw material melt (11) through W, and seeding was carried out by controlling the temperature of the heaters (4) and (5).

Then, the seed crystal (9) was placed at a height of 5.5n+m while controlling the degree of rotation to keep the melt (indicated by 8 in both Figures 1 and 2) at a constant height where the crystal grows.
/hr', the crucible (3) is raised at a speed of 5non/hr, and the seed crystal (9) and crucible (3) are rotated in the same direction at 3 rpm to pull up the GaAs single crystal, and the raw material melt in the crucible is (11) was completely solidified.

After solidification was completed, the crystals were moved outside the crucible and cooled. The Ga AS single crystal thus obtained had very little polycrystalline formation and was of good quality.

〔Effect of the invention〕

As described above, according to the present invention, by keeping the temperature gradient constant during crystal growth, defects such as polycrystals and twins can be prevented from occurring, and the diameter of the manufactured single crystal can be improved, which was previously difficult to achieve by increasing the diameter. It is very easy to control the crystal orientation, and it is possible to produce a highly pure ■-V group compound semiconductor having a circular crystal orientation in the <ioo> direction, which brings about remarkable industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a diagram showing a temperature profile inside a high-pressure vessel used for producing the single crystal of the present invention. ■ - Stainless steel high pressure vessel 2 - Crucible shaft 3 - Crucible 4 - Melt zone heater 5 Low temperature range heater 6 Seed crystal shaft 7 - Insulation material 8 - Viewing rod 9 - One seed crystal YO - B20. Melt 11 Raw material melt

Claims (7)

[Claims] (1) The upper surface of the III-V group compound semiconductor melt in a crucible surrounded by an inert gas atmosphere of 1 atm or more is coated with the melt and an inert nonvolatile liquid encapsulant melt. , this I
Bringing a seed crystal of a II-V compound semiconductor into contact with the semiconductor melt and moving the crucible and seed crystal to an upper low temperature region,
The melt in the crucible that comes into contact with the seed crystal is solidified and
- I characterized by obtaining a single crystal of a group V compound semiconductor
A method for manufacturing a crystal of a II-V group compound semiconductor. (2) The temperature of the melt zone where the III-V compound semiconductor is in a melt state is set to be above the melting point of the semiconductor and below 100°C higher than the melting point, and the temperature of the low temperature region is set to below the above melting point and 300°C above the melting point. I according to claim (1) where the temperature is lower than or equal to a low temperature.
A method for manufacturing a crystal of a II-V group compound semiconductor. (3) PBN (Pyrolitic Boron) is used as the material for the crucible containing the III-V group compound semiconductor melt.
Nitride), quartz or AlN (
1) or (2), the method for producing a crystal of a III-V compound semiconductor; (4) When moving the crucible and seed crystal to an upper low-temperature region to solidify the III-V group compound semiconductor, the pulling speed of the seed crystal is set higher than the moving speed of the crucible to reduce the speed difference to 20 mm/hr. A method for producing a crystal of a III-V compound semiconductor according to claim (1), (2) or (3) as follows. (5) Claim in which Ar, N_2, CO_2 or CH_4 or a mixture thereof is used as the inert gas (
A method for producing a crystal of a III-V compound semiconductor according to any one of 1) to (4). (6) The method for manufacturing a III-V compound semiconductor crystal according to any one of (1) to (5), wherein the seed crystal and the crucible are moved upward while rotating in the same direction. (7) The method according to any one of claims (1) to (6), wherein a magnetic field is applied to the III-V group compound semiconductor melt during solidification.
A method for producing a crystal of a III-V compound semiconductor.