JPS59131600A - Production of compound semiconductor single crystal having high decomposition pressure - Google Patents

Abstract

PURPOSE:To produce a single crystal of a compound semiconductor having high decomposition pressure, in high yield and workability, by detecting the pressure in the bomb for supplying an inert gas and in the closed vessel, and controlling the feeding or discharging flow rate of the inert gas according to the detected data. CONSTITUTION:An inert gas is supplied from the bomb 15 to the closed vessel 1 in the growth of a compound semiconductor crystal having high decomposition pressure, e.g. GaP, etc. The pressure of the inert gas is controlled to keep the output level of the pressure sensor A36 at a constant level. The pressure in the vessel 1 is detected constantly during the pulling of the crystal by the pressure sensor B34, and the difference of the output signals of both sensors 34 and 36 is converted to an electrical signal by the device C37. When the pressure difference exceeds the preset level, the solenoid valve V1 (25) of the bypass discharge line 26 is opened and the inert gas is discharged from the system little by little through the needle valve V2 (27). As an alternative method, the solenoid valve V3 (31) of the bypass feed line 30 is opened, and the inert gas is supplied to the vessel 1 through the needle valve V4 (32). The lowering of the yield of a single crystal caused by the pressure fluctuation in the vessel can be prevented by this process.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for producing single crystals of high decomposition pressure compound semiconductors such as GaP, GaAs*InP, etc.
.

The present invention relates to a method for producing a GaAa single crystal.

[Technical background of the invention]

A conventional high-resolution-pressure compound semiconductor single crystal growth apparatus used for manufacturing single crystals such as GaP*GaAs will be described with reference to FIG.

In the figure, reference numeral 1 denotes a pressure-resistant airtight container. A support shaft 2 is rotatably inserted from the bottom of this airtight container 1. A carbon heater 3 is supported on this support shaft 2, and the quartz inside Ruth? 4 is protected. Further, an electrode 5°5 is inserted from the bottom of the sealed container 1, and
It is connected to a cylindrical carbon heater 6 which is arranged so as to be recessed. A heat insulating tube 7 is disposed around the outer periphery of the carbon heater 6. On the other hand, a pulling shaft 8 is rotatably inserted into the upper part of the closed container 1, and a seed crystal 9 is held at the lower end of the pulling shaft 8. Further, a viewing window 10 for observing the inside of the quartz crucible 4 is provided on the side surface of the sealed container 1. Furthermore, a pipe 11 is connected to the side surface of the closed container 1. The other end of this pipe 11 is branched into two branch pipes 12a and 12b, and one branch pipe 12a is connected to a supply pipe 14 via a supply valve I3.
and the other end of this supply pipe 14 is connected to an inert gas cylinder 15. Still, the other branch pipe 12
A discharge pipe 17 is connected to b via a discharge valve 16.

Production of a high decomposition pressure compound semiconductor single crystal using the above-mentioned growth apparatus is carried out as follows.

First, after putting raw materials including a compound semiconductor and B206 into the quartz crucible 4, pressurized inert gas is supplied from the inert gas cylinder 15, and electricity is applied to the carbon heat 6 to melt the raw materials, and the compound semiconductor and B206 are put into the quartz crucible 4. A semiconductor melt 18 and a B2O3 melt 19 covering the surface thereof are formed. This B20
'3 melt 19 has the effect of suppressing decomposition and volatilization from compound semiconductor melt 18. Subsequently, the seed crystal 9 at the lower end of the pulling shaft 8 is immersed in the compound semiconductor melt 18, and the pulling shaft 8 is pulled up while rotating the support shaft 2 and the pulling shaft 8 in opposite directions to achieve high decomposition. Manufacture a pressure compound semiconductor single crystal.

[Problems with background technology]

In the above-described conventional high decomposition pressure compound semiconductor single crystal growth apparatus, a closed container 1 that is pressure resistant to pressurized inert gas is indispensable in order to prevent decomposition and volatilization of high decomposition pressure components (PrAs, etc.). Therefore, during actual single crystal growth, the volume of the container remains constant, and the pressure and temperature change proportionally. By the way, high decomposition pressure compound semiconductor single crystals are generally manufactured by controlling the temperature and controlling the diameter according to a program with a constant growth rate. However, for the reasons mentioned above, changing the temperature to control the diameter changes the pressure. However, as the thermal environment changes as the crystal grows, the pressure also changes accordingly.

As a result of these pressure fluctuations, it is difficult to control the temperature at the crystal interface in a programmed energization manner, leading to polycrystalization and twinning, which causes a decrease in the yield of compound semiconductor single crystals. . In addition, pressure fluctuations also caused deterioration in the reproducibility of the temperature program used to control the crystal diameter.

[Purpose of the invention]

The present invention has been made in view of the above circumstances. By suppressing pressure fluctuations in a closed container, the present invention improves the yield of single crystals and improves the reproducibility of temperature programs. The present invention aims to provide a method for producing a high decomposition pressure compound semiconductor single crystal that can be easily grown.

[Summary of the invention]

In the method for producing a high decomposition pressure compound semiconductor single crystal of the present invention, the pressure inside the cylinder and the closed container is detected by, for example, a pressure sensor, and the pressure difference between the two is a predetermined value (for example, 1 factor of the cylinder pressure).
When the above conditions are reached, the amount of inert gas supplied or discharged is adjusted.

In this way, pressure fluctuations within the closed container can be suppressed, improving the yield of single crystals and facilitating single crystal growth operations.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described with reference to FIG. Note that the same members as those in the conventional growth apparatus shown in FIG. The end has two branch pipes 21a, :)1
b, and a branch pipe 22 is formed between the connection part on the side surface of the closed container 1 and the branch part. This branch pipe 22 has a discharge valve (vout) 2.
A main discharge pipe 24 is connected via 3. Further, the one branch pipe 21a is connected to a bypass discharge pipe 26 via a solenoid valve (Vl) 25, and this bypass discharge pipe 26 is connected to the main discharge pipe 24. It should be noted that a needle valve (v2) 27 is interposed in the gas discharge pipe 26 downstream of the electromagnetic valve (v,)j5.

A supply valve ('vtn) is provided in the other branch pipe 21b.
A main supply pipe 29 is connected via zs, and the other end of this main supply pipe 29 is connected to the inert gas cylinder 15. In addition, the branch pipe 21b and the main supply pipe 29 are provided with pi A'
A solenoid valve (V3) 31 and a needle valve (V4) J2 are interposed in this pi/iso supply pipe 30 in this order from the connecting portion with the main supply pipe 29. Further, a detection pipe 33 branches from the branch pipe 21b and connects to the pressure sensor (B) a 4, and a detection pipe 35 branches from the main supply pipe 29 and connects to the pressure sensor (A) s e
is connected to. These pressure sensor (A) s 6 and pressure sensor (B) s 4 are connected to a converter 37 that converts the output difference between them into an electrical signal.
7 outputs the electric signal to the solenoid valve (V, ) 25 and solenoid valve (3) 31.

In the above-mentioned growth apparatus, the inert gas is usually in cylinder 1.
5 into the closed container 1 via the main supply pipe 29, supply valve (Vin) 28, branch pipe 21b and pipe 20, and from inside the closed container 1 to the pipe 20. Branch pipe 22, discharge valve (Vo
ut ) 23 and discharge pipe 24 to the outside.

Using the above-mentioned growth apparatus, GaP was grown under the following conditions.
A single crystal was produced.

First, 2 kg of GaP polycrystal and B2O were placed in the quartz mill 4.
After charging 3, increase the pressure of cylinder 15 to 1000p.
si (70.21 kg, 7 cm2), and the carbon heater 6 was energized to melt the GaP polycrystal. Next, the seed crystal 9 at the lower end of the pulling shaft 8 is immersed in the GaP melt 18,
Seed crystal rotation speed 10-15rpm, crucible rotation speed 3-5r
pm, pulling speed 9-15 mf'ki, weight 1.
A GaP single crystal weighing 5 kg and having a diameter of 52±2 gourds was pulled.

At this time, the pressure fluctuation inside the closed container 1 is equal to the cylinder pressure 1000.
less than ±1 inch of psi (70,21kg/crn2), i.e. ±10 psi (0,7021kg/cm
2) The pressure was adjusted as follows so that the pressure of the inert gas supplied from the cylinder 15 was adjusted to 1000.
psi (70, 21kvz2), and - maintain the output value of the pressure sensor ゛(A)se at a constant value XA.

The pressure inside the sealed container I during crystal pulling is measured by a pressure sensor (B).
The difference between the output value XB of the pressure sensor (B) 34 and the output value XA of the pressure sensor (A) s e is constantly detected by the converter (C) 37. Here, the difference between the above output values, XB-XA, is +10 ps+ (
+0.7021kg/crn2), by opening the solenoid valve (vl) 25 of the bypass discharge pipe 26, the inert gas is passed through the needle valve (■2) 27 little by little. The solenoid valve (vl) 25 is automatically closed when xB-XA:0 is discharged to the outside. Also, x
B-xA is -10psi (-0,7021kvcrn
When the value corresponding to 2) is reached, the solenoid valve (V3) 3z of the bypass supply pipe 30 is opened and the inert gas is supplied to the needle valve (
v4) 32 into the sealed container 1, and when xB xA=Q, the solenoid valve (v3) 31 is automatically closed.

According to the above method, it is possible to prevent the temperature of the crystal interface from deviating from the programmed value due to pressure fluctuations within the closed container 1.

Therefore, it is possible to prevent polycrystalization and twinning of crystals during the pulling process. In fact, if a GaP single crystal is produced by the conventional method without adjusting the pressure inside the closed container 1, all other conditions being the same, the pressure fluctuation inside the closed container 1 will be 50 to 100 psi (3,511 to 7.021 psi).
kvcm), and the rate of decrease in yield of GaP single crystals due to this pressure fluctuation was 10%, whereas in the case of the method of the present invention, the pressure fluctuation inside the closed container 1 was l Q psi(
The yield of GaP single crystals did not decrease due to this pressure fluctuation. ” In addition, since pressure fluctuations can be suppressed, the reproducibility of the temperature program for controlling the crystal diameter is improved.
Single crystal growth operations have become easier.

In the above example, the pressure difference between the cylinder and the inside of the closed container was set to 1% of the cylinder pressure when adjusting the supply or discharge amount of inert gas, but the pressure difference is determined by the single crystal yield system. It can be set arbitrarily within a range that does not affect.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to provide a method for producing a high decomposition pressure compound semiconductor single crystal, which can improve the single crystal yield and facilitate the single crystal growth operation.

[Brief explanation of drawings]

FIG. 1 is a partially cross-sectional block diagram of a conventional high-resolution-pressure compound semiconductor single crystal growth apparatus, and FIG. 2 is a partial cross-section of a high-resolution-pressure compound semiconductor single-crystal growth apparatus used in an embodiment of the present invention. FIG. 1... Airtight container, 2... Support shaft, 3... Car? 4...quartz glass, 5...electrode, 6...
Carden heater, 7... Heat insulation cylinder, 8... Pulling shaft, 9
... Seed crystal, 10... Peephole, 15... Inert gas cylinder, 18... Compound semiconductor (GaP) melt, I9... B2O5 melt, 20... Piping, 21a,
21b... Branch pipe, 22... Branch pipe, 23... Discharge valve, 24... Main discharge pipe, 25.31... Solenoid valve,
26... Bypass discharge pipe, 2'7, 32... Needle valve, 28... Supply valve, 29 Main supply pipe, 3o...
Bypass supply pipe, 33.35...Detection pipe, 34.3
6...Pressure sensor, 37...Converter.

Claims (1)

[Claims] Inert gas? A pressurized inert gas is supplied into the sealed container from the container, and the seed crystal is immersed in the high decomposition pressure compound semiconductor melt in the crucible supported in the sealed container, and the cup crucible and the seed crystal are rotated. In a method for producing a high decomposition pressure compound semiconductor single crystal by pulling up a seed crystal while detecting the pressure inside the container and the closed container, when the pressure difference between the two becomes more than or less than a predetermined value, A method for producing a high decomposition pressure compound semiconductor single crystal, which comprises adjusting the amount of inert gas supplied or discharged.