JPH06256082A - Apparatus for producing compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To make the form of the growing interface to be symmetrical in lateral direction during the crystal growth and to enable the stable growth of a compound semiconductor single crystal using a boat method by symmetrically arranging plural power-supply terminals with respect to the center line of the heater. CONSTITUTION:The heater part for the heating of a growing crystal in an apparatus for the production of a compound semiconductor single crystal by a boat method is composed of plural zones. Plural terminals for the independent supply of power to each zone are arranged in the form of a straight line at a position immediately above the heater. As an alternative, the attaching positions 3 are made to be symmetrical with respect to the center line A of the heater in the longitudinal direction of the furnace when viewed from above. The thermocouples 4 for the temperature determination are also placed at positions symmetrical with respect to the center line A of the heater in the longitudinal direction of the furnace when viewed from above. Electric power is supplied to the heater through each terminal and a compound semiconductor single crystal is grown by a boat method. The temperature difference generating in the lateral direction in the furnace can be decreased to prevent the generation of troubles such as defective lineage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a compound semiconductor single crystal by a boat method such as a horizontal Bridgman method (HB method) or a temperature gradient method (GF method).

[0002]

2. Description of the Related Art The boat method is a horizontal Bridgman method (HB
Method) and a temperature gradient method (GF method). In both cases, the raw material is put into a long boat and crystallized from one end of the boat in a horizontal furnace having a temperature gradient in the longitudinal direction to produce a single crystal. Is the way.

Since the boat method has a small temperature gradient in the crystal growth portion, it is necessary to precisely control the temperature distribution in the furnace, particularly in the vicinity of the solid-liquid interface. Here, the important temperature gradient is important not only in the furnace longitudinal direction and the vertical direction but also in the horizontal direction perpendicular to the furnace longitudinal direction (hereinafter referred to as the horizontal direction). If there is a temperature difference in the left-right direction, the crystal growth interface bends left and right, and lineage, which is a crystal defect, is likely to occur.

In the apparatus for producing a compound semiconductor single crystal by the boat method, the terminal position for supplying electric power to the heater wire has generally been conventionally provided at an appropriate position. In consideration of the temperature distribution in the furnace, the terminal position is considered. Was never set. Since this terminal is directly welded to the heater wire, the heater temperature at the terminal welded portion was locally lowered, which also affected the temperature distribution in the furnace. Therefore, when the mounting position of the terminal is asymmetrical in the left-right direction, a temperature difference occurs in the left-right direction, and a lineage defect often occurs due to the above reason.

Further, since the mounting position of the temperature measuring sensor (thermocouple, etc.) mounted on the heater part has been conventionally set appropriately, the thermocouple part is locally cooled, which affects the temperature distribution in the furnace. I was giving.

[0006]

SUMMARY OF THE INVENTION The present invention seeks to overcome the aforementioned drawbacks of the prior art.

[0007]

The present invention has been made to solve the above-mentioned problems, and should be grown at least during crystal growth in an apparatus for producing a compound semiconductor single crystal using the boat method. The mounting position of the terminal for supplying electric power to the heater in the portion for directly heating the crystal is provided at a position substantially symmetrical with respect to the heater center line in the furnace longitudinal direction when viewed from the vertical direction. An apparatus for producing a compound semiconductor single crystal is provided.

Further, as a preferred embodiment of the present invention, in a device for producing a compound semiconductor single crystal by using a boat method, it is provided along at least a portion near a heater for directly heating a crystal to be grown during crystal growth. Another object of the present invention is to provide an apparatus for producing a compound semiconductor single crystal, in which a temperature measuring sensor is provided at a position substantially symmetrical with respect to a heater center line in the furnace longitudinal direction when viewed from the vertical direction.

Further, as another preferred embodiment of the present invention, at least one of the power supply terminal and the temperature measuring sensor is provided substantially vertically above the heater (approximately the uppermost portion of the furnace body) or vertically. An apparatus for producing a compound semiconductor single crystal provided below (almost at the bottom of the furnace body).

The configuration of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a cross-sectional view of a heater portion composed of a heater wire and a heat insulating material as viewed from the furnace longitudinal direction. In this example,
All joints with the terminals attached to the heater wire shall be placed almost vertically above the heater. It is preferable that the terminal connected to the power source outside the heat insulating material is also arranged almost vertically above the heater because it is easy to keep the temperature distribution in the furnace symmetrical.

FIG. 1 is a plan view of a heater portion composed of a heater wire and a heat insulating material as viewed from above. In the figure, the heater center line in the furnace longitudinal direction is the direction indicated by arrow A. This heater section is composed of 10 zones in order to arbitrarily control the temperature distribution in the longitudinal direction in the furnace. Eleven terminals are attached to the top of the heater to supply power to the ten zones independently. A thermocouple as a temperature sensor is also attached to the upper part of the heater. Especially, the position where the terminal is attached is important in the part where the crystal exists during the crystal growth, but the terminal position and the thermocouple position at both ends of the furnace where the crystal does not exist also depend on the heat transfer through the furnace core tube. Due to the temperature difference, it is preferable to mount them symmetrically as shown in FIG.

FIG. 3 is a plan view of a heater portion composed of another type of heater wire and heat insulating material. This heater part is composed of 10 zones in order to accurately control the temperature distribution in the longitudinal direction in the furnace, and it is necessary to take out two terminals at positions approximately the same distance from the furnace end in the furnace longitudinal direction. An example of the case is shown. The mounting position of these two terminals to the heater wire is substantially symmetrical with respect to the heater center line in the furnace longitudinal direction when viewed from the vertical direction,
All other terminals are located almost vertically above the heater.

It is also preferable that the thermocouple 4 serving as a temperature measuring sensor is also provided substantially above or below the heater. When installing a thermocouple on the side of the furnace body, install it so that it is symmetrical in the left-right direction. In that case, the dummy thermocouples 4a can be arranged in symmetrical positions without performing temperature measurement.

[0014]

In the apparatus for producing a compound semiconductor single crystal by the boat method, since the terminal for supplying electric power to the heater wire is directly welded to the heater wire, the heater temperature at the terminal welded portion is locally lowered, and It also affects the temperature distribution of. Therefore, by making the terminal mounting positions symmetrical as described above, it is possible to reduce the temperature difference generated in the horizontal direction in the furnace. Therefore, it is possible to suppress the bending of the crystal growth interface in the left-right direction, which occurs when there is a temperature gradient in the left-right direction, and lineage, which is a crystal defect, and to grow the crystal with a high yield.

For the same reason, the temperature sensors (thermocouples, etc.) attached to the heater section are also symmetrically arranged, so that the temperature distribution in the horizontal direction in the furnace can be reduced and the yield can be improved. improves.

[0016]

EXAMPLES Examples for producing a GaAs single crystal will be described below.

(Embodiment 1) FIG. 1 is a plan view of a heater portion composed of a heater wire and a heat insulating material, and FIG. 2 is a sectional view seen from the furnace longitudinal direction (direction A in FIG. 1). 1 and 2
In FIG. 1, 1 is a heater wire, 2 is a terminal joining portion, 3 is a terminal lead-out portion, 4 is a thermocouple, 4 a is a dummy thermocouple, 5 is a heat insulating material, 6 is a furnace core tube, and 7 is a crystal observation window. The heater portion has a heat insulating material having a long and thin tubular shape as a whole, and a crystal observation window is formed on an upper wall portion of the heat insulating material. A heater wire having 10 zones is wound around the inner circumference of the heat insulating material.

The terminals for supplying electric power to the heater wire are arranged in a straight line in the longitudinal direction of the furnace substantially vertically above the heater (uppermost part of the furnace body). The thermocouples for temperature measurement were also arranged in a straight line in the longitudinal direction of the furnace almost above the heater. Further, a furnace core tube is arranged in the inner peripheral portion of the heater, and a crystal growth boat placed in a reaction vessel is installed inside the furnace core tube for crystal growth.

FIG. 4 shows a side sectional view in the longitudinal direction of the reaction container in the case of growing. In the figure, 8 is a seed crystal, 9 is a boat, 10 is Ga, 11 is a reaction vessel, and 12 is As.

As shown in FIG. 4, two Ga10 are placed in the boat 9.
Put 100 g, and add As12 to the other end of the reaction vessel 11
The reaction vessel 11 is filled with 00 g, and the inside of the reaction vessel 11 is depressurized to a vacuum state and sealed. Next, the reaction vessel 11 is put into a crystal growth furnace, and the reaction vessel 1
As in 1 is heated to 600 ° C., As in reaction vessel 11 is heated.
The vapor pressure is maintained at 1 atm, the boat in the reaction vessel 11 is set to 1200 ° C., and Ga and As vapor are reacted to synthesize GaAs.

Thereafter, the temperature is further raised to set the seed crystal temperature to 123.
At 8 ° C., the temperature gradient in the GaAs melt is set to about 0.5 ° C./cm, and the seed crystal and the GaAs melt are brought into contact with each other. After that, the temperature of the melt is gradually lowered and cooled to grow crystals. At this time, the crystal-solid interface shape observed from the observation window in the upper part of the furnace body was almost symmetrical. After completely solidifying, the temperature was further lowered to room temperature and crystals were taken out. The obtained crystals are EPD500 to 1000 / cm without lineage defects.
² was good. As a result of repeating the same crystal growth 10 times, it was confirmed that the average yield was 90% or more and the reproducibility was also good.

FIG. 5 shows a typical example in which this crystal was cut parallel to the free surface of the crystal upper part and the growth interface shape was observed by etching. The left direction in the figure is the direction of crystal growth. As shown in FIG. 5, the shape of the growth interface was substantially parallel to the growth direction and was substantially symmetrical.

(Comparative Example) FIG. 6 shows a plan view of a heater portion composed of a heat insulating material and a heater wire in which a terminal and a thermocouple are taken out to one side in the horizontal direction. The other structure is basically the same as that of the embodiment.

As in the example, as shown in FIG. 4, 2100 g of Ga10 is put in the boat 9, 2300 g of As12 is put in the other end of the reaction vessel 11, and the inside of the reaction vessel 11 is depressurized to a vacuum state and sealed. Next, the reaction vessel 11 is put into a crystal growth furnace, As12 in the reaction vessel 11 is heated to 600 ° C., and the As vapor pressure in the reaction vessel 11 is maintained at 1 atm. The boat inside the reaction vessel 11 is heated to 1200 ° C., and Ga and As vapor are reacted to synthesize GaAs.

Thereafter, the temperature is further raised to set the seed crystal temperature to 123.
At 8 ° C., the temperature gradient in the GaAs melt is set to about 0.5 ° C./cm, and the seed crystal and the GaAs melt are brought into contact with each other. Then, the temperature of the melt is gradually lowered and cooled to grow crystals. At this time, the crystal solid-liquid interface shape observed from the observation window on the upper part of the furnace is asymmetrical due to large solidification on the heater terminal side.
Moreover, the interface shape was not stable. After completely solidifying, the temperature was further lowered to room temperature and crystals were taken out. The obtained crystal had lineage defects in the direction in which the growth was delayed.
As a result of performing similar crystal growth, the average yield was 50% or less.

FIG. 7 shows a typical example in which this crystal was cut parallel to the free surface of the crystal upper part and the growth interface shape was observed by etching. As shown in FIG. 7, the growth interface shape was tilted with respect to the growth direction, and was similar to the shape observed during crystal growth.

[0027]

The present invention has an effect that the growth interface shape during crystal growth becomes bilaterally symmetric, growth is stable, lineage defects are not generated, and yield and throughput are improved.

[Brief description of drawings]

FIG. 1 is a plan view of an example of a heater portion having a symmetrical shape.

FIG. 2 is a sectional view of an example of a heater portion having a symmetrical shape.

FIG. 3 is a plan view of an example of a heater portion having a symmetrical shape.

FIG. 4 is a longitudinal sectional side view of a reaction container.

FIG. 5 is an explanatory diagram of an example of observing a growth interface shape in a cross section parallel to a crystal upper free surface grown by a symmetrical heater unit.

FIG. 6 is a plan view of an example of a heater portion having an asymmetrical shape.

FIG. 7 is an explanatory diagram of an example of observing a growth interface shape in a cross section parallel to a free upper surface of a crystal grown by an asymmetric heater unit.

[Explanation of symbols]

 1: Heater wire 2: Terminal welding part to the heater wire 3: Terminal extraction part 4: Thermocouple 4a: Dummy thermocouple 5: Heat insulating material 6: Furnace core tube 7: Crystal observation window 8: Seed crystal 9: Boat 10: Ga 11: reaction vessel 12: As

Claims (3)

[Claims] 1. An apparatus for producing a compound semiconductor single crystal using a boat method, wherein at least a terminal for supplying electric power to a heater for directly heating a crystal to be grown during crystal growth has a mounting position from a vertical direction. An apparatus for producing a compound semiconductor single crystal, which is provided at positions substantially symmetrical with respect to a heater center line in a furnace longitudinal direction. 2. In a device for producing a compound semiconductor single crystal by using a boat method, a temperature measuring sensor provided along at least a portion of a heater for directly heating a crystal to be grown during crystal growth is a vertical sensor. The apparatus for producing a compound semiconductor single crystal according to claim 1, wherein the apparatus is provided at a position substantially symmetrical with respect to the heater center line in the longitudinal direction of the furnace when viewed from the direction. 3. The production of a compound semiconductor single crystal according to claim 1, wherein at least one of the power supply terminal and the temperature measuring sensor is provided substantially vertically above or below the heater. apparatus.