JPH0426581A - Production of compound semiconductor single crystal and apparatus for producing this crystal - Google Patents

Abstract

PURPOSE:To stabilize the crystal growth boundary at the time of crystal growth and to uniformize a crystal growing speed by providing a heat radiating hole in the upper part of a furnace body forming a high-temp. part and opening and closing this heat radiating hole to control the temp. distribution in the furnace according to the amt. of opening and closing thereof. CONSTITUTION:The detection value of a thermocouple 15 is applied to a control circuit 22 by which both are compared and the control circuit 22 outputs a control signal to an actuator 23 to control the opening/closing angle of an opening/closing door 14 in such a manner that the detected value of the thermocouple 15 is equaled to a set value. The set values most adequate for a temp. falling process are previously set stepwise in a setting circuit. The set values are empirifically obtd. and are properly corrected and changed even during the crystal growth. The opening/closing angle of the pening/closing door 14 is adjusted in accordance with the set values at the time of producing the compd. semiconductor crystal by lowering the temp. while maintaining the prescribed temp. distribution formed in the high-temp. furnace 31, by which the fluctuation in heat radiating conditions is suppressed and the heat radiation quantity at the crystal growth boundary position is stabilized and uniformized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a compound semiconductor crystal manufacturing apparatus and a manufacturing method thereof, and particularly to a boat method compound semiconductor crystal manufacturing apparatus using a temperature gradient solidification method (GF method). and its manufacturing method.

[Prior Art] The upper half of FIG. 3 shows a schematic configuration example of a compound semiconductor crystal manufacturing apparatus using the conventional GF method.

30 is a double resistance heating furnace, which has a high temperature furnace 31 that provides a melt holding temperature and a low temperature furnace 32 that provides a vapor pressure temperature. This resistance heating furnace 30 that implements the GF method will be referred to as a GF furnace hereinafter.

A quartz ampoule 35 is inserted into the GF furnace 30 in the axial direction of the furnace body. Inside this quartz ampoule 35 is a diffusion barrier 3.
A quartz boat 36 is set on one side of the high temperature furnace 31, and a group 3 element 33 is set on the other side of the low temperature furnace 32. A molten liquid 34 of m--group elements is placed in the quartz boat 36, and a seed crystal 39 of ■-v group elements is placed at the end of the boat.

! ! 1! By forming an arbitrary temperature distribution in the high-temperature furnace 31 that provides a liquid holding temperature, and lowering the temperature while maintaining this temperature distribution, the melt 34 is solidified from one end of the 360 seed crystals of the boat. , a compound semiconductor crystal is obtained by crystallizing the entire melt.

By the way, in the GF method, in order to obtain a defect-free compound semiconductor crystal, it is necessary to solidify the melt 34 from the crystal free surface, and for this purpose, a heat radiation hole 37 is provided in the upper part of the high temperature furnace 31 for heat radiation. A structure is adopted in which heat is dissipated from the free surface of the crystal.

[Problem to be solved by the invention] However, in the conventional GF furnace 30 described above,
The heat radiation hole 37 has a finite length approximately equal to the length of the boat 36, and as shown in the temperature characteristics shown in the lower half of FIG.
7 has the disadvantage that the heat dissipation conditions change in the length direction.

In other words, the temperature distribution a in the longitudinal direction of the high-temperature furnace in the lower part of the ampoule 35, which is not affected by the heat radiation holes 37, can be lowered while maintaining this temperature distribution, but the crystal freedom, which is directly affected by the heat radiation holes 37, can be lowered. Regarding the longitudinal distribution of the high temperature furnace on the surface, as shown in the figure, the heat dissipation conditions change as the temperature decreases, and the distribution becomes significantly different from the temperature distribution in the lower part of the ampoule, which is overlapped with the dotted line.

For this reason, the solidification rate of the melt 34 fluctuates and the crystal solid-liquid interface fluctuates, creating a state in which crystal defects are likely to occur, resulting in unstable crystal growth.

Note that this is also due to a change in heat radiation conditions depending on the width direction of the heat radiation hole 37.

In order to eliminate such a problem, it is only necessary to adjust the amount of heat radiation from the heat radiation holes 37 and change the heat radiation conditions during crystal growth due to temperature decrease. However, as shown in FIG.
It has a fixed structure in which 3 layers are alternately stacked. In addition, in the figure, 40 is a refractory, and 41 is a heater wire.

With such a fixed structure, the amount of heat dissipation is determined by the insulation material 42@ and the number of laminated layers, so the heat dissipation conditions are always constant, and the crystal solid-liquid interface and crystal growth rate change during crystal growth. It is not possible to change the heat dissipation conditions to control variations in the heat dissipation conditions.

Particularly when attempting to thicken the crystal and increase its area, variations in heat dissipation conditions greatly affect crystal growth, further increasing the occurrence of crystal defects, and causing major problems in terms of both quality and productivity.

An object of the present invention is to provide a novel compound semiconductor crystal manufacturing apparatus and method for manufacturing the same, which eliminates the drawbacks of the prior art described above and can significantly improve the stabilization of the crystal growth interface during crystal growth and the uniformity of the crystal growth rate. It is about providing.

[r! Means for Solving Problem R] The compound semiconductor crystal manufacturing apparatus of the present invention uses a heating furnace having a high temperature section and a low temperature section, and cools the compound semiconductor while maintaining a predetermined temperature distribution formed in the high temperature section. In a compound semiconductor crystal manufacturing apparatus for manufacturing crystals, a heat radiation hole is provided in the upper part of the furnace body forming the high temperature section to release heat in the furnace, and the heat radiation hole is opened and closed according to the amount of opening and closing of the heat radiation hole. It is equipped with an opening/closing means to control the temperature distribution inside the furnace.

Further, the compound semiconductor crystal production method of the present invention uses a heating furnace having a high temperature section and a low temperature section, and lowers the temperature while maintaining a predetermined temperature distribution formed in the high temperature section to produce a compound semiconductor crystal. In this manufacturing method, the amount of heat released from the inside of the furnace is varied to control the crystal growth interface and crystal growth rate.

[Function] According to the present invention, the heat radiation hole provided in the upper part of the high temperature section has
Since the opening/closing means that can open and close the heat radiation hole is provided, the amount of heat radiation can be adjusted by opening and closing this opening/closing means, and as a result, the heat radiation is closely related to the crystal growth interface shape and crystal growth rate. It becomes possible to adjust the conditions, and it is possible to suppress fluctuations in heat dissipation conditions during crystal growth.

This makes it possible to significantly improve the stabilization of the crystal growth interface and the uniformity of the crystal growth rate.

[Example 1] An example of the present invention will be described below with reference to FIGS. 1 and 2. The basic structure of the GF furnace is the same as the conventional example.

FIG. 1 shows an upper cross-sectional structure of a high temperature furnace 31 of a GF furnace into which a quartz ampoule 35 is inserted. An elongated heat radiation hole 17 is provided in the upper part of the high temperature furnace 31 in the axial direction of the furnace body to release part of the heat generated in the furnace.

The heat radiation hole 17 is formed by hollowing out the refractory 40 in the upper part of the furnace body. As in FIG. 3, the opening position of the heat radiation hole 17 is directly above the quartz ampoule 35 and extends from the tip of the quartz boat on which the seed crystal is placed to near the rear end of the boat containing the melt.

The heat dissipation hole 17 formed as described above has the heat dissipation hole 1
A quartz glass plate 12 having a frontage 16 with a diameter slightly smaller than that of 7 is mounted.

The opening 16 opened in the quartz glass plate 12 is communicated with the heat radiation hole 17, and a double opening 1114 is attached to the opening 16 as an opening/closing means for opening and closing the heat radiation hole 17 in the upper part of the furnace body. The opening/closing door 14 is configured so that its opening/closing angle can be freely adjusted, and the temperature distribution in the furnace can be arbitrarily controlled according to the amount of opening/closing. Opening/closing door 14
It is preferable to use a heat insulating material.

In order to detect the heat radiation temperature emitted from the heat radiation hole 17,
A pair of thermocouples 15,15 with their detection ends facing the opening 16 are mounted on the quartz glass plate 12.

FIG. 2 is a block diagram showing a control system for opening/closing s14.

21 is open and close! ! This is a setting circuit that can arbitrarily set the amount of heat radiation between the opening and closing angles of 114, and the set value is set by the control circuit 2.
Add to 2. The detected value from the thermocouple 15 is also added to the control circuit 22, the two are compared, and the control circuit 22 outputs a control signal to the actuator 23 so that the detected value of the thermocouple 15 becomes equal to the set value. The opening/closing angle of the opening/closing Ji 14 is controlled.

The most appropriate setting values for the temperature decreasing process are set in advance in the setting circuit 211 in stages. However, this set value is obtained empirically, and can be corrected and changed as appropriate even during crystal growth.

When manufacturing a compound semiconductor crystal by lowering the temperature while maintaining a predetermined temperature distribution formed in the high temperature furnace 31, fluctuations in heat radiation conditions are suppressed by adjusting the opening/closing angle of the opening/closing door 14 based on the set value. However, it becomes possible to stabilize and make the amount of heat dissipated at the crystal growth interface position uniform. Thereby, the crystal growth interface and crystal growth rate can be controlled effectively.

Furthermore, by arbitrarily adjusting the amount of heat dissipation, it becomes possible to easily cope with the need to increase the thickness and area of the crystal without changing the structure of the furnace body. As a result, the occurrence of crystal defects such as polycrystals, twins, and lineages can be significantly reduced, and the amount of WJk work such as remelting due to the occurrence of these defects can also be greatly reduced, resulting in a significant improvement in quality and productivity. You can improve.

In addition, although the said Example demonstrated the case where the opening-and-closing means was a double-door opening-and-closing door, this invention is not limited to this. For example, it may be of a sliding type, a diaphragm type, or the like. Further, the opening/closing means provided in the heat radiation hole may be configured to open and close the entire area of the heat radiation hole, or may be configured to open and close a portion thereof.Furthermore, as shown in FIG. It is also possible to replace a part of the heat insulating material 42 with an opening/closing means.

[Effect of the invention] According to the present invention, the following effects are achieved.

(1) According to the apparatus of the present invention, although it has a simple structure without changing the furnace structure and dimensions, fluctuations in the crystal growth interface and fluctuations in the crystal growth rate can be significantly improved, and stable crystal growth can be obtained.

(2) According to the method of the present invention, stabilization of the crystal growth interface during crystal growth and uniformity of the crystal growth rate can be greatly improved;
It becomes possible to easily handle thicker crystals and larger crystal areas, thereby improving yield and productivity.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of essential parts showing an embodiment of the present invention, Fig. 2 is a block diagram showing a control system of this embodiment, and Fig. 3 is a schematic configuration diagram of a conventional compound semiconductor crystal manufacturing apparatus and a high-temperature furnace. A characteristic diagram showing the internal temperature distribution, and FIG. 4 is a diagram showing the cross-sectional structure of a conventional heat radiation hole. 12 is a quartz glass plate, 14 is an opening/closing door, 15 is a thermocouple, 1
6 is an opening, 17 is a heat radiation hole, 40 is a refractory, 41 is a heater wire, 30 is a GF furnace, 31 is a high temperature furnace, 32 is a low temperature furnace, 3
5 is a quartz ampoule. Heat dissipation amount Configuration according to this embodiment Control system according to this embodiment Fig. 2 Fig. 3 Configuration according to conventional example Fig. 4

Claims (1)

[Scope of Claims] 1. A compound semiconductor crystal production apparatus that uses a heating furnace having a high temperature section and a low temperature section and produces a compound semiconductor crystal by lowering the temperature while maintaining a predetermined temperature distribution formed in the high temperature section, A heat radiation hole is provided in the upper part of the furnace body forming the high-temperature part, and an opening/closing means is attached to the heat radiation hole for opening and closing the heat radiation hole and controlling the temperature distribution in the furnace according to the amount of opening and closing of the heat radiation hole. A compound semiconductor crystal manufacturing device characterized by the following. 2. In a compound semiconductor crystal manufacturing method that uses a heating furnace having a high temperature section and a low temperature section and lowers the temperature while maintaining a predetermined temperature distribution formed in the high temperature section to manufacture a compound semiconductor crystal, A method for producing a compound semiconductor crystal, characterized in that a crystal growth interface and crystal growth rate are controlled by varying the amount of heat.