JPH08268790A - Apparatus for producing single crystal of compound semiconductor and production using this apparatus - Google Patents

Abstract

PURPOSE: To suppress the outflow rate of a dissociation component out of a hermetic vessel provided with a stop valve means by communicating the inside of a chamber enclosing this hermetic vessel with outside in a section apart from a heating means. CONSTITUTION: The hermetic vessel 15 housing a crucible 14 in which a compd. semiconductor raw material and sealant 27 are packed is placed on a supporting table 13 in a high-pressure vessel 1 and is closed with a lower cap 7. Next, the inside of the vessel 1 is evacuated to a vacuum through a gas supply and discharge path 12 and, thereafter, an inert gas is supplied into the vessel 1. Next, electric power is turned on to the heater 3 for heating to melt the sealant 27 and to seal the stop valve means 30. Further, the heating is continued and the pressure of the inert gas in the vessel 15 is increased to the dissociation pressure of the compd. semiconductor or above. The compd. semiconductor raw material in the vessel 15 is heated to melt by maintaining the region of a vent opening 16 at a low temp. below the m. p. of the high dissociation pressure component. The melt in the vessel 15 is cooled from one end side to the other end side to allow the single crystal to grow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is applied to a II-VI group such as ZnSe and CdTe, a III-V group such as InP and GaP, or a ternary compound thereof under high temperature during crystal growth. The present invention relates to an apparatus for producing a single crystal of a compound semiconductor in which a part of constituent components is dissociated and easily evaporated, and a production method using the apparatus.

[0002]

2. Description of the Related Art Conventionally, liquid-encapsulated Czochralski method (LEC method), horizontal Bridgman method (HB method), and vertical Bridgman method (VB) have been used to manufacture single crystals of compound semiconductors in which specific components are easily dissociated and evaporated. Method), vertical temperature gradient solidification method (VGF method), etc. are used. Among them, the VB method and the VGF method are highly expected as industrial methods because they can produce high-quality single crystals that are relatively large and have few dislocations.

By the way, when a specific component dissociates and evaporates, the composition of the formed single crystal shifts and the desired single crystal cannot be obtained. Therefore, the vapor of the dissociated component should not be dissipated, or It is necessary to keep the vapor pressure as intended. Therefore, for example, Japanese Patent Laid-Open No. 5-70276 discloses a method of vacuum-sealing the entire crucible in an airtight container such as a quartz ampoule. However, this method has a problem that the vacuum sealing work in the airtight container and the unsealing work after the growth of the single crystal become very complicated.

Therefore, for example, in Japanese Unexamined Patent Publication No. 3-247582, as shown in FIG. 11, in a vertical temperature gradient furnace, a susceptor 83 supporting a crucible 82 is attached to the upper end of a vertical drive shaft 81, and this susceptor 83 is attached. Liquid sealant around the bottom of
There is disclosed a device in which a pan portion 85 for accommodating 84 is provided and the lower end of the internal chamber 86 covering the crucible 82 is dipped in the liquid sealant 84 to seal the inside of the internal chamber 86. As the liquid sealant 84, boron oxide (B ₂ O ₃ ) that is heated to a high temperature to become a liquid is exemplified.

In the above apparatus, a space for placing the high dissociation pressure component element 87 is further secured on the susceptor 83, the temperature of this space is detected by the thermocouple 88, and the heater 89 is heated based on the detected temperature signal. The vapor pressure of the high dissociation pressure component element 87 is controlled to be controlled. When crystal growth of a compound semiconductor is performed with the above apparatus, a raw material is filled in a crucible 82 having a seed crystal 90 inserted at the lower end thereof, and the raw material is set in a furnace as shown in the figure, and then the raw material is heated and melted. After that, the lower part of the crucible is cooled by providing a predetermined temperature gradient with lower temperature.
The melt 91 in 82 solidifies from the bottom side, and a single crystal 92 grows.

The dissociation during the crystal growth operation is stopped when the vapor pressure of the high dissociation pressure component in the sealed internal chamber 86 reaches the equilibrium vapor pressure. Therefore, in the above, the evaporation amount of the high dissociation pressure component is further suppressed by the internal chamber 86 having a smaller internal space. On the other hand, when a pressure difference is generated between the inside and the outside of the internal chamber 86 due to thermal expansion of the gas due to heating or evaporation of the high dissociation pressure component, the liquid surface of the liquid sealant 84 fluctuates due to the pressure difference, and the saucer portion A gas flow passage is formed inside 85 to communicate the inside and outside of the inner chamber 86. As a result, an excessive force due to the pressure difference does not act on the inner chamber 86, so that the inner chamber 86 is prevented from being damaged.

[0007]

However, in the apparatus described in the above-mentioned prior art, the vapor of the dissociated component flowing out of the internal chamber 86 by changing the liquid surface of the liquid sealant 84 is generated in the internal chamber 86. Diffuses in the outside space. As a result, the heater 89 disposed in this portion
And the power supply member to this, etc. are touched and deposited, and as a result,
A short circuit accident may occur, and the diffused steam contaminates the entire inside of the furnace, so that a great deal of labor is required for maintenance work such as disassembling and cleaning the internal structure of the furnace at any time. For this reason, there is a problem that sufficient manufacturing efficiency cannot be obtained and productivity is lowered.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to maintain a vapor pressure of a high dissociation pressure component inside an airtight container and to heat a heater outside the airtight container. It is possible to prevent the contamination of such structures as described above, thereby providing a method and an apparatus for producing a compound semiconductor single crystal capable of improving the productivity.

[0009]

In order to achieve the above object, a compound semiconductor manufacturing apparatus of the present invention comprises a raw material storage container for storing a raw material of a compound semiconductor, and an airtight container for storing the raw material storage container. A hermetically sealed furnace body having a heating means for heating the raw material storage container from the periphery of the airtight container and having a gas supply and discharge passage connected to the outside, and the airtight container is provided with On-off valve means for opening and closing to form a gas flow passage according to the pressure difference between the inside and outside is provided, while a chamber made of an airtight material surrounding the airtight container inside the heating means is further provided. A ventilation opening for communicating the enclosed internal space with the outside of the chamber is provided at a portion apart from the heating means.

The on-off valve means is, for example, a liquid-like element that closes a communication passage that communicates the inside and the outside of the airtight container and forms a gas flow passage by changing the liquid surface according to the pressure difference between the inside and the outside of the airtight container. A first check valve that is configured by providing a sealant or that opens when the internal pressure of the airtight container is higher than the outside in accordance with the pressure difference between the inside and the outside of the airtight container, and the inside of the airtight container And a second check valve that opens when the pressure is lower than the outside.

On the other hand, it is preferable that a reservoir for containing a high dissociation pressure component element is provided in the airtight container, and the temperature of the seed crystal insertion region in the raw material container is measured in the airtight container. It is preferable that a temperature measuring section for arranging the temperature measuring means is provided. Further, the method for producing a single crystal of a compound semiconductor of the present invention, using the above-mentioned production apparatus, the pressure of the inert gas supplied to the inside of the furnace body to make it an inert gas atmosphere is equal to or higher than the dissociation pressure of the compound semiconductor. Along with holding the region of the ventilation opening in a low temperature state below the melting point of the high dissociation pressure component, after heating and melting the raw material in the raw material storage container, the melt in the raw material storage container from one end side to the other end side. It is characterized in that a single crystal is grown by providing a temperature gradient and cooling.

[0012]

According to the present invention, an on-off valve means that opens and closes according to the pressure difference between the inside and outside of the airtight container, for example, a liquid sealant that forms a gas flow passage by the change of the liquid surface according to the pressure difference is provided. Since the opening / closing valve means provided and the opening / closing valve means provided with the check valve are provided in the airtight container, the airtight container is prevented from being damaged by the pressure difference between the inside and the outside. At the same time, the outflow of vapor generated by dissociation at high temperature from the airtight container is limited only when the pressure inside the airtight container is higher than the outside, and the evaporation of the dissociated component is suppressed to a minimum. . Furthermore, by supplying an inert gas at a pressure higher than the dissociation pressure of the compound semiconductor into the furnace body, the outflow amount of the dissociated components from the airtight container depends on the pressure ratio with the inert gas. Moreover, the outflow of dissociated components is suppressed.

Moreover, as described above, the vapor of the dissociation component flowing out from the airtight container flows through the chamber toward the ventilation opening, but since the ventilation opening is provided at a portion apart from the heating means, This site can be maintained at a lower temperature, and by this, the vapor of the dissociated component flowing to this site can be deposited in the form of droplets or solid. As a result, it is possible to prevent the vapor of the dissociated component from flowing out of the chamber.

If a reservoir for accommodating the high dissociation pressure component element is provided in the airtight container, the dissociation of the raw material is caused by generating the vapor of the dissociation component according to the dissociation pressure of the raw material from this reservoir. Suppressed, which makes it possible to obtain grown crystals with the intended composition. Further, if a temperature measuring means for measuring the temperature of the seed crystal insertion region is provided, the temperature can be monitored so that the seed crystal does not melt when the raw material is melted before starting the crystal growth operation, The temperature can be monitored more accurately.

[0015]

【Example】

Example 1 Next, a specific example of the present invention will be described.
This will be described with reference to FIGS. 1 and 2. FIG. 1 shows an apparatus for producing a single crystal by the vertical temperature gradient solidification method (VGF method).
This apparatus has a high-pressure vessel 1 as a furnace body having a pressure resistant structure.
An upper closed heat insulating structure 2 arranged in the high-pressure container 1, a heater (heating means) 3 arranged inside the heat insulating structure 2, and a gas provided inside the heater 3. And an inverted cup-shaped chamber 4 made of an impermeable material.

The high-pressure container 1 is composed of a cylindrical high-pressure container main body 5 having an upper surface closed, and a lower lid 7 which is detachably attached to a lower opening of the main body 5 and airtightly attached by a seal ring 6. The heater 3 has a plurality of cylindrical heater elements 8 ... in a plurality of vertical stages (three stages in the case of the figure).
The heater elements 8 are arranged side by side, and each heater element 8 ...
A heating power is supplied from the outside through a connector 10 wound around the upper surface of the seal ring 9 and attached airtightly, and a lead wire 11 extending from the connector 10. The supplied power is controlled so that the temperature detected by a temperature detector (not shown) provided at each step is maintained at each set temperature.

The lower lid 7 is further provided with a gas supply / discharge passage 12 for injecting an inert gas such as argon gas into the high-pressure container 1 under pressure and discharging the same. On the lower lid 7, a support base 13 located inside the chamber 4 is placed. An airtight container 15 accommodating a crucible 14 as a raw material container is placed on the support table 13, and the entire airtight container 15 is heated by the heater 3. . The chamber 4
Has a ventilation opening 16 through the inside and outside of the wall surface on the lower end side.
Are formed.

The airtight container 15 is made of a heat-resistant material such as molybdenum. As shown in FIG. 2, a cylindrical main body 21 having a closed lower end and an upper end of the main body 21 are fitted from above. The cup-shaped sealant container 22 and this sealant container 22
An inverted conical cone member 23 that closes the inside from above is provided. Then, the tightening ring that is fitted onto the upper end side of the main body 21.
24 and the screw lid 25 screwed from above to the female screw portion on the inner peripheral surface on the upper end side of the tightening ring 24, the main body 21
The upper end portion of the sealant, the sealant container 22 and the cone member 23 are fixed in a state in which the flange portions of the peripheral edges are in close contact with each other in the axial direction. The peripheral flange-shaped portions of the sealant container 22 and the cone member 23 are hermetically joined by welding. Further, a seal ring 26 for hermetically maintaining the space between the flange-shaped portions of the sealant container 22 and the upper end of the main body 21 is sandwiched.

The space inside the sealant container 22 is divided into upper and lower parts by the cone member 23 (hereinafter, referred to as a cone member).
Above 23 is called upper space A and below is lower space B). Then, at the center of the cone member 23, that is, at the bottommost position corresponding to the apex of the inverted cone shape, a pore 23a is formed which connects the upper space A and the lower space B to each other.
On the other hand, the side wall of the sealant accommodating container 22 is formed with an outer diameter that substantially fits the inner peripheral surface of the main body 21, and on this peripheral surface, inside the main body 21 below the sealant accommodating container 22. Ventilation groove leading to the space
22a is formed in the vertical direction, and at the height position above the pores 23a, the ventilation hole 22b for communicating the upper end of the ventilation groove 22a with the lower space B in the sealant storage container 22 is formed. It is formed in a shape that penetrates the side wall of the sealant container 22. Further, at the center position of the screw lid 25, a central hole that vertically penetrates so that the upper space A communicates with the outside of the airtight container 15.
25a is formed.

The sealant container 22 is filled with a sealant 27 such as B ₂ O ₃ . As shown in the figure, the amount is such that it closes the pores 23a of the cone member 23 when melted and does not spill when the liquid level rises and falls due to the pressure difference between the upper space A and the lower space B. It With such a configuration, in the present embodiment, the sealant accommodating container 22, the cone member 23, and the sealant 27 communicate with each other to connect the inside and outside of the airtight container 15, that is, the ventilation groove 22a to the ventilation hole 22b, An on-off valve means 30 for opening and closing the flow path leading to the lower space B, the pore 23a, the upper space A, and the central hole 25a is configured.

A crucible holding base 28 is placed on the bottom wall of the main body 21 of the airtight container 15, and the crucible 14 is placed and supported in an upright state on the crucible holding base 28. The crucible 14 is made of, for example, p-BN, has an inner diameter of about 15 mm, and has a thin tube portion 14a for inserting a seed crystal 29 at the lower end portion. Next, an example of a procedure and a result when a ZnSe single crystal is manufactured using this apparatus will be described.

First, a rod-shaped rod is attached to the thin tube portion 14a of the crucible 14.
After inserting the ZnSe seed crystal 29, a Raytheon Co.
About 40 g of polycrystalline ZnSe blobs produced by the CVD method were filled. After setting the crucible 14 in the main body 21 of the airtight container 15, a sealing agent 27 made of B ₂ O ₃ powder is attached to the upper end of the main body 21.
The sealant storage container 22 filled with and the cone member 23 were fixed by the tightening ring 24 and the screw lid 25.

Next, after opening the lower lid 7 of the high-pressure container 1 and placing the airtight container 15 on the support table 13, the lower lid 7 is closed to place the airtight container 15 in the high-pressure container 1 as shown in FIG. I set it inside. After that, the inside of the high-pressure vessel 1 was evacuated through the gas supply / exhaust passage 12, and then 5 kgf / cm ² of argon gas was added to the high-pressure vessel 1.
It was supplied inside to replace the internal atmosphere. At this time, since the sealant 27 in the sealant container 22 is powdery, it does not have a great resistance to the flow of gas.

Thereafter, for example, 300 kgf / cm ² of argon gas was injected, and then heating electric power was applied to the heater 3 to start heating. When the temperature rises to 450 ° C during this heating process, the sealant
B ₂ O ₃ as 27 melts and seals the pores 23a of the cone member 23. Continuing to raise the temperature, the upper side of the airtight container 15 is 1550 ° C., which is the melting point of ZnSe of 1526 ° C. or higher, and the lower side is so that the seed crystal 29 does not melt and the heating temperature is adjusted to 1515 ° C. All the raw material ZnSe was melted. At this time, the pressure inside the high-pressure container 1 was 1200 kgf / cm ² .

Thereafter, while maintaining the above temperature gradient, the rate of 3.5 ° C./h was reached until the upper part of the airtight container 15 reached 1510 ° C.
(The temperature was lowered at about 10 hours and the growth rate was about 5 mm / h), whereby the molten ZnSe raw material was grown upward from the bottom side in contact with the seed crystal 29. When the entire melt was solidified and crystallized, the electric power supplied to the heater 3 was lowered, and when the temperature of the furnace was cooled to 150 ° C. or lower, argon gas was discharged to lower the pressure. After reaching the room temperature, open the high-pressure container 1 and take out the airtight container 15, and remove the airtight container 15 from the crucible.
I took out 14.

Although the obtained ZnSe crystal partially contained twin crystals, it was a yellow transparent crystal considered to be one grain as a whole. The weight change was measured and found to be about 0.1%. By the way, in the single crystal growth operation as described above, ZnSe is dissociated until the vapors of Zn and Se in the airtight container 15 reach the equilibrium vapor pressure, as described above. The vapor pressure of this equilibrium is about 2.5 kgf / cm ^{2 for} Zn and about 0 for Se at a melting point of 1526 ° C.
When the airtight container 15 is kept in a hermetically sealed state, the force corresponding to the pressure difference between the inside and the outside acts on the airtight container 15 as much as 9 kgf / cm ² .

However, in the above, the pressure difference between the inside and the outside of the airtight container 15 hardly occurs. For example, when the internal pressure of the airtight container 15 becomes lower than the external pressure, that is, when the pressure of the lower space B becomes lower than the pressure of the upper space A in FIG. When the gas is pushed from the space A side to the B side and reaches the lower end of the pore 23a, the gas flows and the increase of the differential pressure is prevented. The same applies to the opposite case. When the vapor pressure of Zn generated by dissociation of ZnSe by heating or the pressure of the lower space B becomes higher than the pressure of the upper space A due to thermal expansion of the inert gas itself, the sealing agent 27 The liquid surface moves, and a gas in which Zn vapor is mixed with an inert gas is released from the inside through the pores 23a. As a result, an excessive force due to the pressure difference between the inside and the outside does not act on the airtight container 15, and the airtight container 15 is not damaged.

On the other hand, the diffusion movement due to the difference in the concentration of the dissociated components is blocked by the above sealing agent 27. For example, even when the internal Zn vapor pressure is 2.5 kgf / cm ² and the outside Zn vapor pressure is 0 kgf / cm ² , the liquid level of the sealant 27 should not move if the total internal and external pressures are the same. Therefore, the sealant 27 acts as a barrier, and the diffusion movement of vapor between both spaces due to the difference in vapor pressure does not occur.

The pressure of the inert gas sealed in the high-pressure container 1 may be higher than the dissociation pressure of the target compound semiconductor material. A high concentration gas will flow out through the on-off valve means 30, and the components inside the airtight container 15 will decrease during long-term operation, and the composition will shift, so that an inert gas of Higher pressure is more effective. For example, if ZnSe is heated to a temperature near its melting point with an inert gas pressure of 100 kgf / cm ² or more, even if the vapor pressure of Zn generated by dissociation of ZnSe is 3 kgf / cm ^{2 at the} maximum, the check valve is The Zn that opens and flows out is about 3% or less, and the fluctuation of the vapor pressure due to this outflow is suppressed to a very small level.

The dissociation component flowing out of the airtight container 15 to the outside as described above is covered with the chamber 4 at the upper side thereof, so that the natural convection of the inert gas is caused in the chamber 4. Flow. Finally, it descends along the inner wall surface of the chamber 4 toward the ventilation opening 16 provided in the lower portion of the chamber 4. At this time, since the ventilation opening 16 is located sufficiently below the heating region by the heater 3, it is easy to keep this region at a temperature lower than the melting point of the dissociation component.

As a result, the dissociation component descending along the inner wall surface of the chamber 4 as described above is deposited on the lower end of the chamber 4 in the form of droplets or solids. This amount is
In any case, the dissociated gas component is prevented from flowing out of the chamber 4 though it changes depending on the amount and pressure of the raw material. As described above, in the present embodiment, the pressure difference between the inside and outside of the airtight container 15 can be suppressed to a small one,
Even if the airtight container 15 does not have high strength at high temperature, it will not be damaged. Further, the amount of the dissociated component flowing out from the airtight container 15 is suppressed as much as possible and the chamber 4
Since it does not flow out from the inside, the inside of the high-pressure vessel 1 is prevented from being contaminated by this dissociated component, and it is prevented from being deposited on the heater 3, the lead wire 11, the connector 10, etc. and causing a short circuit accident. To be done.

Further, in the apparatus described in the above-mentioned conventional publication,
Boron oxide used as a liquid sealant has a melting point of about
Since the temperature is 450 ° C., it solidifies when the temperature becomes lower than this in the cooling process, and the internal chamber 86 and the susceptor 83 shown in FIG. 11 stick to each other. Therefore, it becomes difficult to take out the crucible 82 after the crystal growth operation is completed, and in order to avoid this, the internal chamber 86 is pulled up and separated from the susceptor 83 in a high temperature state during cooling before the boron oxide is solidified. I need to put it. Therefore, during this period, the dissociation component flowing out of the internal chamber 86 increases the pollution in the furnace.

On the other hand, in the above-described embodiment, the sealant container 22 for containing the liquid sealant 27 has the main body 21 with the tightening ring 24 and the screw lid 25 on the upper end side away from the sealant 27. Are mechanically fastened to. As a result, even if the liquid sealant 27 that has been liquefied is solidified during the cooling process, the above fastening structure is not affected. Therefore, in this embodiment, the airtight container is
Since cooling to near room temperature can be continued while maintaining the closed state of 15, the evaporation of dissociated components can be suppressed and the grown crystals can be easily taken out.

Further, in the above-described embodiment, since the pore 23a is formed at the center of the inverted conical cone member 23 and the liquid sealant 27 is provided so as to close the pore 23a, the liquid sealing is performed. The filling amount of the stopper 27 can be reduced as much as possible, and the entire structure can be made smaller. [Embodiment 2] Next, another embodiment of the present invention will be described with reference to FIGS. For convenience of explanation, members having the same functions as the members shown in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted. The same applies to other embodiments described later.

FIG. 3 shows the structure of the airtight container 15 used in this embodiment. It is generally known that it is effective to shift the vapor pressure of the dissociation component from the equilibrium pressure when adjusting the composition of the single crystal according to the intention. Usually, in order to perform such an operation, a reservoir that separately stores only the high dissociation pressure component element is provided and the temperature thereof is adjusted. Therefore, in the present embodiment, as shown in the figure, the lower end portion of the crucible holding base 28 in the airtight container 15 is provided with a space in which a reservoir 32 for accommodating the high dissociation pressure component element 31 can be arranged. ing. The storage space of the reservoir 32 and the disposition space of the crucible 14 above the crucible holding base 28 communicate with each other through a gap 33 between the outer peripheral surface of the crucible holding base 28 and the inner peripheral surface of the main body 21. In addition,
As in the first embodiment, the sealant container 22 and the cone member 23 are fixed to the upper portion of the main body 21 by the tightening ring 24 and the screw lid 25.

The airtight container 15 having the above structure is set in the manufacturing apparatus by the vertical Bridgman method shown in FIG. In this device, the lower end opening of the high-pressure container body 5 has a ring-shaped lower lid.
7a and an inner lower lid 7b fitted from below so as to close the central opening of the ring-shaped lower lid 7a, and are covered by two members. On the other hand, the high-pressure container main body 5 is formed in an upper end opening shape, and a gas supply / discharge path 12 is provided in an upper lid 5a that detachably covers the opening.

On the ring-shaped lower lid 7a, a cylindrical chamber holder 34 is provided upright along the inner peripheral edge thereof. The heat insulating structure 2 and the chamber 4 are supported by the upper end of the chamber holder 34. The chamber holder 34
A ventilation opening 16 is formed at a lower end portion of the air passage 16 so that an inner space surrounded by the holder 34 and the chamber 4 mounted thereon communicates with an outer space thereof.

An elevating rod 35 extending vertically through the center of the inner lower lid 7b is provided so as to be airtight with the inner lower lid 7b. A support base 13 is provided on the upper end of the lifting rod 35.
Is attached to the outer periphery of this support base 13.
A reservoir heating heater 36 for heating the reservoir 32 placed on 13 is attached. On the other hand, similar to the first embodiment, the heater 3 provided outside the chamber 4 has a pair of upper and lower heater elements 8 at three positions in the heat insulating structure 2, that is, the upper side, the center, and the lower side. It is provided and configured. The electric power supplied to these heater elements 8 is adjusted so that the temperature inside the chamber 4 is maintained at a predetermined temperature distribution in which the temperature rises upward. Therefore, by raising and lowering the elevating rod 35 to change the height position of the airtight container 15 in the chamber 4, temperature control of the upper side of the airtight container 15, that is, the storage portion of the crucible 14 is performed.

At this time, the lower side of the airtight container 15,
That is, the temperature of the reservoir 32 is controlled independently of the region of the crucible 14 by the reservoir heating heater 36 that moves up and down integrally with the support base 13 in the vicinity of the storage portion of the reservoir 32. In addition, the crucible holding table 28 is provided on the side of the reservoir 32 with the crucible 14
In order to maintain the temperature difference when controlling the temperature independently of the side,
A material having a small thermal conductivity is preferable, but a material having a small specific gravity and not so porous such as graphite can also be used.

In such an apparatus configuration, the airtight container 15 can be taken in and out at the time of single crystal growth by the operation of lowering only the inner and lower lids 7b. The chamber holder 34 on the ring-shaped lower lid 7a and the chamber 4 thereabove, and the heater 3 arranged outside of these chambers are operated while being left in the high-pressure container 1 during normal times other than maintenance and inspection. To be done.

A specific operation procedure and an example of the result when a ZnSe single crystal is manufactured using the above airtight container 15 and the manufacturing apparatus will be described. First, the seed crystal 29 and the raw material similar to those in Example 1 are housed in the crucible 14, and the reservoir is stored.
32 was filled with 5 g of zinc. After that, the airtight container 15 is shown in FIG.
As shown in (1), after setting in the high pressure vessel 1 to replace the atmosphere gas inside, heating was started while the argon gas supply pressure into the high pressure vessel 1 was maintained at 75 kgf / cm ² .

The upper side of the airtight container 15, that is, the crucible
The 14 regions were placed in the temperature gradient part of 5 ° C./cm near the melting point of ZnSe of 1526 ° C. to melt the raw material. After that, the airtight container 15 was moved downward at a speed of 3 mm / h to grow crystals from the melt. At this time, if a composition of Zn: Se = 1: 1 is intended, the lower side of the airtight container 15, that is, the reservoir 32 is
It suffices to control the temperature to around 1000 ° C., and in this embodiment, the region where the reservoir 32 is arranged is kept at 1030 ° C. After the crystal growth operation was completed, the pressure and temperature were returned to recover the grown crystal from the crucible 14.

The obtained crystals were yellowish transparent crystals with a slight green tint. Generation of twins was observed, but it was judged as one grain as a whole. No change in weight was observed. In addition, as a result of measuring the specific resistance value of the sample, about 5
At Ωcm, a crystal having a considerably low resistance was obtained. In the present embodiment, during the above crystal growth operation, the vapor of the dissociation component corresponding to the dissociation pressure of the upper raw material in the airtight container 15 is dissociated and generated in the reservoir 32. As a result, dissociation of the raw material and the grown crystal is suppressed as much as possible, and the grown crystal having the intended composition is obtained.

In each of the first and second embodiments, the sealant container 22 and the cone member 23 are welded and joined together. However, as shown in FIG. The seal ring 37 is attached to the mating surface of the peripheral brim portions of the 22 and the cone member 23.
It is also possible to further clamp and tighten. In this case, the sealant inside the sealant container 22
It becomes easy to fill 27 and cleaning work after use becomes easy.

Further, as shown in the figure, when the bottom portion of the sealant accommodating container 22 is made to have a lower central portion, the amount of the sealant 27 is reduced and the cone member 23 is Pore 23a
The height of the liquid surface that closes Further, as the sealing agent 27, those having a low vapor pressure are preferable, and there are various materials such as metallic gallium, but as exemplified in each of the above examples,
B ₂ O ₃ having a melting point of about 450 ° C. and good handleability is preferable.

Further, as shown in the figure, a thermocouple (temperature measuring means) 38 can be inserted into the main body 21 in the vicinity of the thin tube portion 14a at the lower end of the crucible 14.
In this case, since the thermocouple 38 deteriorates when exposed to the vapor of the crystal growth raw material, the bottom wall surface of the main body 21 is provided with a pore-shaped recess extending to a position close to the lower end of the crucible 14, and the thermocouple 38 is provided in this recess. Insert pair 38. Thermocouple 38 is a protective tube made of ceramics such as alumina or heat-resistant metal such as molybdenum.
It is set in the form stored in 39.

By providing such a thermocouple 38,
The temperature can be monitored so that the seed crystal 29 is not melted when the raw material is melted before the crystal growth operation is started, or the temperature during growth can be monitored more accurately. [Embodiment 3] Next, still another embodiment of the present invention will be described with reference to FIGS.

FIG. 6 shows the airtight container 15 used in this embodiment. The airtight container 15 includes a cylindrical main body 41 that penetrates vertically, and an upper plug 44 and a lower portion that are screwed by sandwiching seal members 42 and 43 so as to close the upper end and the lower end of the main body 41, respectively. The upper plug 44, and a communication path 46a that vertically penetrates the center of the upper plug 44,
A first check valve 46 including a valve body 46b vertically movably inserted is provided in the communication passage 46a.

In the first check valve 46, when the pressure in the airtight container 15 is equal to or lower than the external pressure, the lower end taper portion of the valve body 46b is
The reduced diameter shoulder portion of the communication passage 46a is held in contact with the reduced diameter shoulder portion by its own weight, whereby the communication passage 46a is held in the closed valve state. On the other hand, when the pressure inside the airtight container 15 becomes higher than the outside, the valve body 46b is pushed up against its own weight, and when the taper portion is separated from the reduced diameter shoulder portion, the communication passage 46a is opened to open the valve. The gas in the airtight container 15 flows out to the outside.

A stopper member 46c is attached to the upper end of the communication passage 46a in order to prevent the valve body 46b from being pulled out upward. Further, a guide pin 46d in the form of a small-diameter rod is provided at the upper end of the valve body 46b so as to project upward through the center hole of the stopper member 46c. It is possible to adjust the pressure difference (cracking pressure) required for the valve element 46b to rise to the valve opening position by placing a weight separately on the upper end of the guide pin 46d.

On the other hand, in the lower plug 45 as well,
A second check valve 47 including a communication passage 47a formed therein and a valve body 47b for opening and closing the communication passage 47a is provided.
A stopper member 47c is attached to the upper end of the communication passage 47a in order to prevent the b from being pulled out upward. The valve body 47b is
When the pressure in the airtight container 15 becomes lower than the outside, the airtight container 15 is pushed up to open the valve, and at this time, gas flows from the outside into the airtight container 15.

Then, the crucible holding table 28 is mounted on the lower plug 45.
The crucible 14 is placed on the crucible holding table 28.
Is supported upright. The airtight container 15 described above is
As shown in FIG. 7, the apparatus is set in a manufacturing apparatus having substantially the same structure as the single crystal manufacturing apparatus by the vertical temperature gradient solidification method in the first embodiment.

An example of the manufacturing procedure and the result of manufacturing the ZnSe single crystal with the manufacturing apparatus having the above structure will be described. First, the crucible 14 filled with the same seed crystal 29 and the ZnSe raw material as in Example 1 was housed in the airtight container 15, and the airtight container 15 was set as shown in FIG. 7. Then, after evacuating the inside of the high-pressure container 1 through the gas supply / exhaust path 12, further supplying 5 kgf / cm ² of argon gas into the high-pressure container 1 to replace the internal atmosphere, and then,
It was filled with 300 kgf / cm ² of argon gas.

Then, heating power is applied to the heater 3 to start heating, and the upper side of the airtight container 15 is heated to 1550 ° C., and the lower side is heated to 1515 ° C. so that the seed crystal 29 does not melt and remains. The temperature was adjusted. At this time, the pressure in the high-pressure container 1 is 12
It became 00 kgf / cm ² . While maintaining the above temperature gradient, the rate of 3.5 ° C / h until the upper part of the airtight container 15 reaches 1510 ° C.
The temperature was lowered at about 10 h and the growth rate was about 5 mm / h. Thus, the melted ZnSe raw material was crystal-grown upward from the bottom side in contact with the seed crystal 29.

When the entire melt was solidified and crystallized by the above-mentioned operation, the electric power supplied to the heater was lowered, and when the temperature of the furnace was cooled to 150 ° C. or lower, argon gas was released to lower the pressure. . When the temperature reached almost room temperature, the high-pressure container 1 was opened, the airtight container 15 was taken out, and the crucible 14 was taken out from the airtight container 15. Although the obtained ZnSe crystal partially contained twin crystals, it was a yellow transparent crystal considered to be one grain as a whole. The weight change was measured and found to be about 0.1%.

During the crystal growth operation as described above, in this embodiment, an excessive force due to the differential pressure acts on the hermetic container 15 by the two check valves 46 and 47 provided on the hermetic container 15. Is prevented. That is, when the pressure outside the airtight container 15 becomes a differential pressure equal to or higher than the cracking pressure of the second check valve 47 with respect to the internal pressure when the inert gas is supplied into the high pressure container 1,
The inert gas flows into the airtight container 15, and the vapor pressure of Zn generated by ZnSe dissociated by heating, or the thermal expansion of the inert gas itself increases the pressure in the airtight container 15.
When the cracking pressure of the first check valve 46 becomes higher than the external pressure, a gas in which Zn vapor is mixed with an inert gas is released from the inside. As a result, the pressure difference between the inside and the outside is always maintained between the cracking pressures of the two check valves 46 and 47, and the airtight container 15 is not damaged.

Further, the dissociated component flowing out upward from the airtight container 15 through the first check valve 46 is covered with the chamber 4, and thus the dissociated component in the lower portion of the chamber 4 is the same as in the first embodiment. It flows toward the ventilation opening 16 and is deposited on the lower end of the chamber 4 in the form of droplets or solids. As a result, the dissociated gas component is prevented from flowing out of the chamber 4, so that the dissociated gas component is deposited on the heater 3, the lead wire 11 and the connector 10 which supply power to the heater 3, and causes a short circuit accident. Is prevented.

In the above embodiment, the first check valve 46 and the second check valve 47 are described by incorporating the valve bodies 46b and 47b each having a taper portion on the lower end side. However, in addition to this, for example, as shown in FIG. 8 (a), spherical valve bodies 46b, 47b are provided and configured, and as shown in FIG. 8 (b), soft seal plates 46b ₁ , 47b ₁ , The valve bodies 46b and 47b composed of the weights 46b ₂ and 47b ₂ are used, and the soft seal plates 46b ₁ and 47b ₁ are brought into contact with the valve seats of the upper sharpened points provided in the communication passages 46a and 47a from above. It is also possible.

Since the check valves 46 and 47 as described above are used at a high temperature of 1000 ° C. or higher as described above, it is difficult to use a spring to apply a load for closing the valve. Since the cracking pressure when the valve is opened is determined by the weight of the valve bodies 46b and 47b itself, the structure is simplified and a stable operating state can be secured even at high temperature.

In the valve bodies 46b and 47b shown in FIG. 7B, the weights 46b ₂ and 47b ₂ are selected according to the desired cracking pressure. On the other hand, FIG. 6 (c) shows the first check valve 46 and the second check valve 47 in which the spherical valve bodies 46b and 47b are provided in duplicate, respectively, which also increases the cracking pressure. Is also possible, and the function as a check valve is exhibited more reliably.

In order to provide the check valves 46 and 47 for holding the closed state by gravity as described above in the long cylindrical airtight container 15, as shown in FIG. It is effective to arrange the check valves 46 and 47 so that gas flows in from the above and flows out from above, and it is possible to suppress the enlargement of the shape by adopting the check valve structure as much as possible. , But is not necessarily limited to this.

[Fourth Embodiment] Next, still another embodiment of the present invention will be described with reference to FIGS. 9 and 10. Figure 9
The structure of the airtight container 15 used in this example is shown in FIG. The airtight container 15 has a structure in which a growth container part 50 and a reservoir container part 51 are vertically connected to each other via a connection pipe 52. That is, as in the second embodiment, the reservoir 58 that stores only the dissociated component can be built in the airtight container 15.

The growth container section 50 closes a cylindrical body section 53, an upper ring 54 and a lower ring 55 welded to the upper and lower sides of the body section 53, and central openings of both rings 54, 55. As described above, the upper plug 56 and the lower plug 57, which are airtightly screwed, are provided. And in the upper plug 56,
A first check valve 46 similar to that of the third embodiment is provided.
On the other hand, the upper end of the connecting pipe 52 is airtightly coupled to the center hole of the lower plug 57. This growth container section
A crucible holding base 28 is provided in 50, and the crucible holding base 28 is provided.
A crucible 14 is housed above.

On the other hand, the reservoir 58 containing the dissociated component is accommodated in the reservoir container 51 welded to the lower end of the connecting pipe 52. By heating this reservoir 58, vapor of the dissociation component having a vapor pressure according to the heating temperature is generated. Then, the inside of the reservoir container portion 51 and the inside of the growth container portion 50 are in communication with each other,
The vapor pressure of the dissociated components in the growth container section 50 is also determined by the reservoir container section.
Controlled to match the vapor pressure in 51.

A reservoir container plug 59 that closes the lower end surface of the reservoir container portion 51 is screwed in an airtight manner.
The reservoir container plug 59 is provided with a second check valve 47 similar to that of the third embodiment. This airtight container
Most of 15 is composed of a refractory metal such as molybdenum. This is because molybdenum is easily available as a gas impermeable material, and it is easy to realize an airtight structure by welding. Of course, it is also possible to use an airtight carbon material or boron nitride.

As shown in FIG. 10, the airtight container 15 having the above structure is set in an apparatus having the same structure as the manufacturing apparatus (see FIG. 4) by the vertical Bridgman method described in the second embodiment. An example of the manufacturing procedure and the result of the above apparatus will be described below. First, the crucible 14 filled with the same seed crystal 29 and raw material as in Example 1 was housed in the growth container portion 50 of the airtight container 15, while the reservoir 58 was filled with 5 g of Zn. After setting the airtight container 15 in the high pressure container 1,
The internal gas was replaced with argon gas, and then the supply pressure of the argon gas was set to about 75 kgf / cm ^2, and this pressure state was maintained.

In this state, after melting the raw material in the growth container part 50, the growth container part 50 is placed in a temperature gradient part of 5 ° C./cm near the melting point of 1526 ° C. and an airtight container at a speed of 3 mm / h. By moving 15 downward, ZnSe single crystal was grown. At this time,
The temperature of the reservoir container portion 51 was maintained at 1030 ° C. After completing the crystal growth operation, return the pressure and temperature, and then
The grown crystals were recovered from 14.

The obtained crystals were yellowish transparent crystals with a slight green tint. Generation of twin crystals was observed, but it was judged as one grain as a whole. No change in weight was observed. As a result of measuring the specific resistance value of the grown crystal,
A crystal having a considerably low resistance was obtained at about 5 Ωcm. Also in this embodiment, as in the second embodiment, the dissociation of the raw material and the grown crystal is suppressed as much as possible by the generation of the vapor of the dissociation component according to the dissociation pressure in the reservoir 58. A grown crystal of composition is obtained.

Comparative Example 1 A ZnSe single crystal was prepared by the same procedure and conditions as in Example 1 except that the same device as in Example 1 was used and no sealant was placed in the sealant container 22. A growth operation was performed. The obtained grown crystals showed a remarkable weight loss visually and had a metallic black color. When the weight was measured, it was reduced by about 20%. In addition, yellow and reddish brown powdery substances were deposited in the lower part of the inner surface of the inverted cup-shaped chamber, and an offensive odor that seems to be a selenium compound was produced.

[Comparative Example 2] Using the apparatus of Example 3,
With the first check valve 46 of the upper plug 44 kept open, the ZnSe single crystal growth operation was performed in the same procedure as in Example 3. The obtained grown crystals showed a remarkable weight loss visually and had a metallic black color. When the weight was measured, it was reduced by about 20%. In addition, yellow and reddish brown powdery substances are deposited on the lower part of the inner surface of the chamber 4,
There was a strange odor that seems to be a selenium compound.

As described above, in each of the above embodiments,
If the high-pressure container 1 as a furnace body has sufficient strength, the pressure when pressurized with an inert gas is, for example, 1000 kg.
Even at a high pressure such as f / cm ² , the airtight container 15 for holding the vapor pressure of the high dissociation pressure component will not be damaged.
Therefore, a compound semiconductor single crystal having a high dissociation pressure at a high temperature near the melting point can be manufactured by effectively utilizing the pressure of the high-pressure inert gas. Moreover, it is possible to prevent contamination of structures inside the furnace, such as the heater 3 outside the airtight container 15, and it becomes very easy to fill the crystal growth raw material and recover the single crystal after the growth. Therefore, it can greatly contribute to its industrial use.

In each of the above examples, the production of ZnSe single crystal was described as an example. For example, a group II-VI such as CdTe, InP, GaP.
III-V group such as, or these ternary compounds,
The present invention can be applied to the production of other compound semiconductor single crystals in which some of the constituent elements are dissociated at high temperature and easily evaporated.

[0073]

As described above, according to the present invention, the airtight container provided with the opening / closing valve means and the chamber surrounding the airtight container are provided, and the inside of the chamber is externally provided at a position away from the heating means. Since it is configured so as to communicate with, even when producing a compound semiconductor single crystal having a high dissociation pressure at a high temperature, it is possible to further reduce the outflow amount of the dissociation component from the airtight container, It is possible to prevent the dissociated component from flowing out of the chamber. As a result, contamination of structures inside the furnace, such as the heater outside the airtight container, can be prevented, and maintenance work required for this can be reduced, thus improving productivity.

Further, a reservoir for accommodating the high dissociation pressure component element is provided in the airtight container, and the dissociation of the raw material is suppressed by generating the vapor of the dissociation component according to the dissociation pressure of the raw material. As a result, a grown crystal having a composition as intended can be obtained, which also improves productivity. In addition, a temperature measuring means for measuring the temperature of the insertion region of the seed crystal is provided to monitor the temperature so that the seed crystal does not melt when the raw material is melted before starting the crystal growth operation, or to measure the temperature during growth more accurately. By monitoring the temperature and controlling the temperature, the quality of the grown crystal becomes more stable, which also improves the productivity.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view showing the configuration of a single crystal manufacturing apparatus in one example of the present invention.

FIG. 2 is a vertical cross-sectional view showing an airtight container set in the single crystal manufacturing apparatus.

FIG. 3 is a vertical sectional view showing an airtight container according to another embodiment of the present invention.

FIG. 4 is a schematic vertical cross-sectional view showing the configuration of a single crystal manufacturing apparatus in which the airtight container shown in FIG. 3 is set.

FIG. 5 is a vertical cross-sectional view showing a modified example of the airtight container containing the liquid sealant according to the present invention.

FIG. 6 is a vertical sectional view showing an airtight container according to still another embodiment of the present invention.

7 is a schematic vertical cross-sectional view showing the configuration of a single crystal manufacturing apparatus in which the airtight container shown in FIG. 6 is set.

8 (a) to 8 (c) are vertical sectional views showing modifications of the airtight container provided with the check valve according to the present invention.

FIG. 9 is a vertical sectional view showing an airtight container according to still another embodiment of the present invention.

10 is a schematic vertical cross-sectional view showing the configuration of a single crystal manufacturing apparatus in which the airtight container shown in FIG. 9 is set.

FIG. 11 is a schematic vertical cross-sectional view showing the internal configuration of a conventional single crystal manufacturing apparatus.

[Explanation of symbols]

 1 High-pressure container (furnace body) 3 Heater (heating means) 4 Chamber 12 Gas supply / discharge passage 14 Crucible (raw material storage container) 15 Airtight container 16 Vent opening 27 Sealant 29 Seed crystal 30 Open / close valve means 32 Reservoir 38 Thermoelectric Pair (Temperature measuring means) 46 1st check valve 47 2nd check valve

Front page continuation (72) Inventor Kazuya Suzuki 2-3-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Takasago Works, Kobe Steel Co., Ltd. (72) Hiroshi Okada 1-5, Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture No. 5 Inside Kobe Research Institute of Kobe Steel, Ltd. (72) Takeho Kawanaka 5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Inside Kobe Research Institute of Kobe Works (72) Inventor Seiichiro Omoto 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel Works, Ltd. Kobe Research Institute

Claims (6)

[Claims] 1. A raw material storage container for storing a raw material of a compound semiconductor, an airtight container for storing the raw material storage container, and a heating means for heating the raw material storage container from the periphery of the airtight container and are connected to the outside. And a closed furnace body having a gas supply and discharge passage, and the airtight container is provided with an on-off valve means for opening and closing to form a gas passage according to a pressure difference between the inside and the outside of the airtight container. On the other hand, a chamber made of an airtight material surrounding the airtight container inside the heating means is further provided, and a ventilation opening for communicating the internal space surrounded by the chamber to the outside of the chamber is provided at a position apart from the heating means. An apparatus for producing a single crystal of a compound semiconductor, which is provided. 2. The liquid-state valve means for closing the communication passage communicating the inside and outside of the airtight container and forming a gas flow passage by the change of the liquid surface according to the pressure difference between the inside and the outside of the airtight container. 2. The compound crystal single crystal manufacturing apparatus according to claim 1, further comprising a sealing agent. 3. A first check valve, wherein the opening / closing valve means opens when the internal pressure of the airtight container is higher than the outside in accordance with the pressure difference between the inside and the outside of the airtight container, and the inside of the airtight container. 2. A compound semiconductor single crystal production apparatus according to claim 1, further comprising a second check valve that opens when the pressure is lower than the outside. 4. The apparatus for producing a single crystal of a compound semiconductor according to claim 1, wherein the airtight container is provided with a reservoir for storing a high dissociation pressure component element. 5. The airtight container is provided with a temperature measuring unit for arranging a temperature measuring unit for measuring the temperature of the seed crystal insertion region in the raw material storage container. 5. A compound semiconductor single crystal manufacturing apparatus according to any one of 1 to 4. 6. A manufacturing method performed by using the apparatus for producing a single crystal of a compound semiconductor according to claim 1, wherein the inert gas in the furnace body supplied to create an inert gas atmosphere in the furnace body is used. While keeping the pressure above the dissociation pressure of the compound semiconductor and maintaining the region of the vent opening at a low temperature below the melting point of the high dissociation pressure component, the raw material in the raw material storage container is heated and melted, and then melted in the raw material storage container. A method for producing a single crystal of a compound semiconductor, which comprises growing a single crystal by cooling a liquid by providing a temperature gradient from one end side to the other end side.