JPH09208375A - Apparatus for heat treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for heat treatment capable of stably forming especially a steep temperature gradient and thereby producing a single crystal of good quality when applied to, e.g. an apparatus for producing the single crystal. SOLUTION: This apparatus for heat treatment is capable of installing heat insulating materials (12a) to (12c) for mutually dividing the heat insulating materials (12a) to (12c) among heaters (11a) and (11d) arranged side by side along the outer surface of an inner chamber 3 and arranging a heat insulating material (12b) having a great thickness at a position corresponding to a steep temperature gradient region AG in the formed temperature distribution, thereby improving the independence of the control for each of the respective heaters (11a) to (11d) and stably forming the steep temperature gradient. As a result, a single crystal of good quality, etc., reduced in crystal defects can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal growth apparatus for growing a single crystal and a heat treatment apparatus such as a ceramics sintering furnace.

[0002]

2. Description of the Related Art III-V group compound semiconductors such as GaAs and InP,
As a method for producing II-VI group compound semiconductors such as CdTe and ZnSe, horizontal Bridgman method (HB method), vertical Bridgman method (VB method), solidification method with horizontal temperature gradient (HGF method), with vertical temperature gradient The solidification method (VGF method) and the pulling method (Czochralski method) are used.

Japanese Unexamined Patent Publication (Kokai) No. 63-174293 discloses an example of a single crystal pulling apparatus using the Czochralski method. In the apparatus, as shown in FIG. 3, a core tube that vertically penetrates the center of a furnace body 51. A heating device 54 formed by arranging six heaters 53 in parallel is provided around 52. Each heater 53 is composed of a resistance heating element made of graphite in which a heating portion is formed in a cylindrical shape, and a flange portion 53 to which a pair of lead electrodes 55 are respectively connected at one end side.
a is provided.

The heater 53 is energized to heat and melt the raw material in the crucible 56 arranged in the furnace core tube 52 to form a raw material melt 57, and a seed crystal is brought into contact with the raw material melt 57 from above. After this, the operation of growing the single crystal 58 from the raw material melt 57 is performed by pulling up this seed crystal. During such a crystal growth operation, a temperature distribution D shown by a chain double-dashed line in the figure, that is, a position slightly above the liquid surface of the raw material melt 57 is set as a melting point temperature range mp, and a temperature below the melting point temperature range mp The electric power supplied to each heater 53 is individually controlled so that a temperature distribution in which the temperature is lowered is formed.

On the other hand, for example, the vertical Bridgman method (VB method)
Contrary to the above, in the apparatus of No. 1, a temperature distribution in which the temperature is higher in the upper part is formed in the furnace. For an example of such a device,
This will be described with reference to FIG. 1, which is an explanatory view of the present invention. In this apparatus, as shown in FIG. 1 (a), on a lifting shaft 5 that hermetically penetrates a lower lid 1c of a pressure vessel 1 as a furnace body. The crucible 6 having the seed crystal 15 inserted at the lower end is supported by the. Then, as shown in FIG. 3B, a temperature position near the upper end of the seed crystal 15 is set as a melting point temperature range mp, and a temperature distribution is formed in which the temperature above the melting point is higher and the temperature below is lower. To lower the elevating shaft 5. As a result, the raw material melt in the crucible 6
16 sequentially solidifies from the lower side in contact with the seed crystal 15 and grows as a single crystal.

When a single crystal of a compound semiconductor, such as GaAs, which is easily dissociated at high temperature, is grown, a high-pressure inert gas is filled in the pressure vessel 1 to suppress the dissociation. Furthermore, a high dissociation pressure component, such as As in the case of GaAs,
The single crystal growth operation described above is performed while providing a reservoir 7 in which is stored and controlling the As vapor pressure around the crucible 6 by the As vapor generated by heating the reservoir. In order to form this vapor pressure controlled atmosphere, an internal chamber 3 that surrounds the crucible 6 and the reservoir 7 is provided in the pressure vessel 1.

[0007] Conventionally, a heating device constituted by arranging the cylindrical heaters as described above in multiple stages along the outer surface of the internal chamber as described above is provided to heat the crucible and the reservoir. The electric power supplied to each heater is individually controlled so that a predetermined temperature distribution is formed in the internal chamber.

[0008]

However, the predetermined temperature distribution cannot be stably maintained only by individually controlling the energization of the heaters provided in multiple stages as described above, and therefore the high quality is achieved. However, it is difficult to obtain a single crystal of. That is, the respective heaters influence each other by heat radiation and heat convection, and therefore the independence of control for each individual heater cannot be obtained. For example, when a change in the energization power according to a deviation from the set temperature occurs in one heater and the amount of heat generated by this heater changes, this affects the adjacent heater, and the energization power of this adjacent heater also changes. Due to such mutual interference, control stability cannot be obtained, and temperature fluctuation is likely to occur.

In particular, if there is temperature fluctuation in the vicinity of the melting point temperature range during the growth of a single crystal, the interface of crystal growth fluctuates and remelting and resolidification are repeated, thereby increasing the number of crystal defects. . From this point of view, it is desirable that the temperature gradient in the vicinity of the melting point temperature range be as steep as possible so that the fluctuation range of the crystal growth interface becomes as small as possible even if temperature fluctuations occur. However, in the configuration of the conventional heating device, it is more difficult to form a steep temperature gradient and hold it stably because the mutual interference between the adjacent heaters is large, and for this reason, crystal defects are caused. It is difficult to obtain a good quality single crystal with a sufficiently reduced density.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to be able to stably form a particularly steep temperature gradient. An object of the present invention is to provide a heat treatment apparatus capable of producing a high quality single crystal when applied.

[0011]

In order to achieve the above object, in the heat treatment apparatus according to claim 1 of the present invention, a plurality of heaters are arranged in parallel along the outer surface of the internal chamber provided in the furnace body. A heat treatment apparatus for forming a predetermined temperature distribution in the internal chamber by energizing these heaters,
Insulating materials that extend between adjacent heaters to positions close to the outer surface of the internal chamber are respectively interposed between the heaters, and a specific insulating material of the above-described insulating materials having a thickness that substantially fills the gap between the adjacent heaters is provided. The heat insulating material is thicker than the other heat insulating materials, and is provided at a position corresponding to a steep temperature gradient region having a locally large temperature gradient in the temperature distribution.

According to this structure, since the heaters are partitioned from each other by the heat insulating material extending to the position close to the outer surface of the inner chamber, mutual interference due to heat radiation and heat convection is reduced, and each heater is separated. Control independence is improved.
In addition, since each heat insulating material is formed with a thickness that almost fills the gap between adjacent heaters, the space around each heater is also made as small as possible, which causes temperature fluctuations due to natural convection in each partitioned area. Becomes smaller and the temperature controllability is improved.

Further, in the above, the thick heat insulating material is provided at the position corresponding to the steep temperature gradient region where the temperature gradient is locally large. That is, when the thickness of the heat insulating material is large in a region having a small temperature gradient, for example, in a region where the temperature is to be maintained at substantially the same temperature, the distance between the heaters sandwiching the heat insulating material becomes large, and as a result, a temperature drop occurs between these heaters. As a result, a predetermined temperature distribution cannot be obtained. Therefore, in the region where the temperature gradient is small, the interval between the heaters is appropriately narrowed, and the thickness of the heat insulating material is set according to these intervals.

On the other hand, when the heaters having the narrow intervals as described above are provided also at the positions corresponding to the steep temperature gradient regions and the control temperatures of the respective heaters are controlled to have a large difference, the heaters are controlled between the heaters. Since the provided heat insulating material is thin, mutual interference between the heaters is not sufficiently reduced, which makes it difficult to stably form the steep temperature gradient region. Therefore, in the above description, the thickness of the heat insulating material in this region is increased, and a predetermined steep temperature gradient region is formed by utilizing the temperature drop between the heaters sandwiching this heat insulating material. In this case, mutual interference is sufficiently suppressed between the heaters on both sides sandwiching the thick heat insulating material. Therefore, one heater is controlled at the set temperature on the high temperature side in the steep temperature gradient region, and the low temperature side control temperature of the other heater is controlled so that the temperature drop caused by the heat insulating material becomes a gradient corresponding to the predetermined steep temperature gradient. By determining and controlling the temperature difference, it becomes possible to stably form a steep temperature gradient region between these heaters that can be controlled independently of each other with high accuracy.

The heat insulating material may be a ceramic material such as BN, SiC, Si ₃ N ₄ , AlN, Al ₂ O ₃ , SiO ₂ , ZrO ₂ or a carbon material. It can be produced by using. Further, in the above heat treatment device,
As described in claim 3, by further comprising a moving means for moving the object to be heated in the internal chamber, the steep temperature is set near the specific temperature at which, for example, a phase change or a material change of the object to be heated occurs. By making the gradient region and moving the object to be heated through this region, the above-mentioned change can be stably generated from one end side to the other end side of the object to be heated.

Therefore, for example, the apparatus according to claim 4, that is, the raw material storage container for storing the raw material that grows as a single crystal by solidifying the raw material melt from the side in contact with the seed crystal as a heated object, When crystal growth is performed with a device configuration in which the temperature gradient region is set to a temperature region that includes the melting point of the single crystal, fluctuations at the growth interface are minimized, thereby suppressing remelting and resolidification of the grown crystal. As a result, a good quality single crystal with reduced crystal defects such as dislocations and twins can be obtained.

When a raw material for crystal growth of a III-V group compound semiconductor or a II-VI group compound semiconductor is used as the raw material as described in claim 5, a high dissociation pressure element among the constituent elements is used. If a reservoir for generating vapor during crystal growth to maintain the predetermined vapor pressure in the internal chamber is further provided in the internal chamber, the occurrence of crystal defects due to compositional deviation can be further suppressed, and thereby ,
Further, it is possible to manufacture a single crystal of a compound semiconductor having excellent quality.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] Next, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 1 (a) shows a heat treatment apparatus configured as a single crystal manufacturing apparatus by the vertical Bridgman method (VB method), which is equipped with a pressure vessel 1 as a furnace body having a pressure resistant structure, This pressure vessel 1 is composed of a cylindrical vessel body 1a, an upper lid 1b that closes the upper opening thereof, and a lower lid 1c that is detachably and airtightly attached to the lower opening.

Inside the pressure vessel 1, there is disposed a heat insulating tube 2 formed of an upper closed tubular body along the lower surface of the upper lid 1b and the inner surface of the vessel body 1a. In this heat insulating cylinder 2, there is provided a heating device 10 to be described later including a plurality of upper and lower stages (four stages in the figure) of cylindrical heaters 11a to 11d.
An inner chamber 3 having a reverse cup shape is arranged so as to surround the inner spaces 11a to 11d in a state of being placed on the lower lid 1c. The internal chamber 3 is made of a material having heat resistance and gas impermeability, for example, a refractory metal such as molybdenum or ceramics, or a special carbon material such as carbon coated with pyrolytic graphite or glassy carbon.

The lower lid 1c is provided with an elevating shaft (moving means) 5 which penetrates the center of the lower lid 1c by a seal ring 4 in an airtight manner. The lifting shaft 5 is configured to be vertically movable by an external drive mechanism (not shown).
A crucible 6 as a raw material storage container is supported. The crucible 6 is made of, for example, p-BN, and a thin tube portion 6a into which a rod-shaped seed crystal 15 to be described later is inserted is provided on the lower end side, and a large diameter cylinder portion 6b has a tapered portion 6c above the thin tube portion 6a. Are serialized through. The cylinder portion 6b is also formed in a tapered shape having an inner diameter of about 80 mm at the upper end and an inner diameter of about 75 mm at the lower end. The lower side of the taper portion 6c and the thin tube portion 6a are fitted into a support hole which is recessed downward from the upper surface of the elevating shaft 5, so that the crucible 6 is substantially upright at the center of the upper side in the inner chamber 3. Supported by.

On the other hand, a thick-walled tube-shaped reservoir 7 having a central hole through which the elevating shaft 5 penetrates is provided on the lower side in the internal chamber 3. The reservoir 7 is formed with an annular groove 7a recessed downward from the upper surface thereof, and the high dissociation pressure element 8 can be accommodated in the annular groove 7a. Although not shown, the upper lid 1b is filled with an inert gas such as argon gas under pressure into the pressure vessel 1,
Further, a gas supply / exhaust passage for discharging gas is provided, and a communication passage that connects the inside and the outside of the internal chamber 3 is formed in the inner chamber 3 at the lower end side near the lower lid 1c.

Next, the structure of the heating device 10 arranged outside the inner chamber 3 will be described. As described above, the heating device 10 is provided with, for example, four stages of cylindrical heaters 11a to 11d at the top and bottom, and these heaters (hereinafter, the first heater 11a, the second heater 11b, the third heater 11b from the top stage side).
Between the heater 11c and the fourth heater 11d) ring-shaped inter-heater heat insulating materials 12a to 12c are respectively arranged, and between the fourth heater 11d and the lower lid 1c, a ring-shaped lower heat insulating material. 13 are provided. Furthermore, each heater 11a-11
Each of the cylindrical outer heat insulating materials 14a surrounds the outer side of d.
~ 14d are provided.

The inter-heater heat insulating materials 12a to 12c for partitioning the heaters 11a to 11d into upper and lower parts are the heaters 11a to 11d.
The inner peripheral surface is formed to be as close as possible to the outer surface of the inner chamber 3 so as to project inward in the radial direction.
Also, regarding the thickness in the vertical direction, the upper and lower surfaces are each heater 11a.
Each heater 11a should be placed as close as possible to the upper and lower ends of 11d.
It is formed according to each gap between 11d.

The heat insulating material 12a between these three heaters
Among these, the heat insulating material between heaters (hereinafter also referred to as the heat insulating material between specific heaters) 12b at the center is configured to be located at a substantially central height position in the high-pressure vessel 1, and this heat insulating material 12b is also included. Is formed thicker than the heat insulating materials 12a and 12c between the heaters above and below it. That is, the single crystal growth operation described later is performed by forming a temperature distribution having a steep temperature gradient region A _G in the approximate center in the height direction, as shown in FIG. Above the steep temperature gradient region A _{G, a} substantially constant temperature region A ₁ higher than the melting point of the grown crystal is formed, and below the steep temperature gradient region A _G, a substantially constant temperature region A ₂ set for heating the reservoir 7 is formed. To be done. If the thickness of the uppermost heat insulating material 12a between the heaters and the third heat insulating material 12c between the heaters at the positions corresponding to the areas A ₁ and A ₂ respectively is increased, the temperature drop between the heaters is reduced. As a result, it becomes impossible to secure the above-mentioned approximately constant temperature regions A ₁ and A ₂ . Therefore, the interval between the first and second heaters 11a and 11b and the third and fourth heaters 11c and 11d is appropriately narrowed, and the thickness is set according to these intervals.

On the other hand, the thickness of the heat insulating material 12b between the specific heaters at the height position corresponding to the steep temperature gradient region A _G is set substantially in accordance with the vertical width dimension of this region A _G , and therefore, this heat insulation is performed. The material 12b is the heat insulating material between the other heaters described above.
It is formed thicker than 12a and 12c. The lower heat insulating material 13 is also formed such that the inner peripheral surface thereof is as close as possible to the outer surface of the inner chamber 3, and the upper surface thereof is the fourth heater 11.
This fourth heater 11d should be located as close as possible to the lower end surface of d.
It is formed to match the space between the lower lid 1c and the lower lid 1c. On the other hand, each of the outer heat insulating materials 14a to 14d has an inner peripheral surface of each heater.
It is formed in a shape as close as possible to the outer peripheral surfaces of 11a to 11d.

As described above, in the heating device 10 according to the present embodiment, the heaters 11a to 11d are vertically divided by the inter-heater heat insulating materials 12a to 12c, and the heaters 11a to 11d are also divided.
Since the inter-heater heat insulating materials 12a to 12c, the lower heat insulating material 13, and the outer heat insulating materials 14a to 14d are provided in a shape close to each other, the heaters 11 in the individually divided areas are provided.
The space around a to 11d is configured to be as small as possible.

Further, each of the above heat insulating materials 12a to 12c, 13 and 14a
The outer peripheral surfaces of the heat insulating tubes 2 to 14d are also formed so as to be close to the inner surface of the heat insulating tube 2, respectively.
The space between and is designed to be as small as possible.
The heat insulating materials 12a to 12c, 13 and 14a to 14d are
For example, select an appropriate material according to the furnace atmosphere gas, operating temperature, etc., such as BN, SiC, Si ₃ N ₄ , AlN, Al ₂ O ₃ , SiO ₂ , ZrO ₂ ceramic materials or carbon materials. Is possible. For example, as will be described later, assuming use in an inert gas such as argon gas (such as argon gas) in a temperature range of about 1200 ° C, Al ₂ O ₃ (alumina)
The material is suitable.

Next, the operation procedure when growing a GaAs single crystal using the above apparatus will be described. First, a seed crystal 15 made of a rod-shaped GaAs single crystal is attached to the thin tube portion 6a of the crucible 6.
Was mounted, and about 6 kg of GaAs polycrystal as a raw material for growing a single crystal was filled on it. On the other hand, the reservoir 7 was filled with an appropriate amount of As as the high dissociation pressure element 8. Then, the crucible 6 and the reservoir 7, and the internal chamber 3 made of molybdenum are installed in the pressure vessel 1 as shown in the figure to seal the pressure vessel 1, and then, through the gas supply / discharge path,
After evacuating the pressure vessel 1 and performing gas replacement with argon gas twice, the argon gas in the vessel 1 is about 2 kgf / cm 2.
^It was filled until the pressure of ² was reached.

At this time, the elevating shaft 5 is held at the upper limit position in its vertical movement range, and as a result, as shown in FIG. 1, in the crucible 6, the upper part of the thin tube portion 6a is provided with the specific heater insulation material 12b. It is held at a height position approximately at the center. After that, energization to each of the heaters 11a to 11d is started, and the inside of the internal chamber 3 is heated while maintaining a temperature distribution state in which the temperature is higher toward the top, and finally the temperature distribution shown in FIG. 3 to be formed and retained in
The power supply to each heater 11a-11d was controlled. In the above temperature distribution, the height of the center of the heat insulating material 12b between the specific heaters is the temperature of the melting point mp (= 1238 ° C.) of GaAs, and the temperature gradient is about 20 ° C. with the melting point temperature range mp being the center. /
A steep temperature gradient region A _{G of} cm is provided.

By forming and heating such a temperature distribution, the raw material melts inside the crucible 6 except for the lower side of the seed crystal 15, and the raw material melt 16 is formed on the seed crystal 15. A temperature region A ₂ of about 618 ° C. is formed below the steep temperature gradient region A _G , and the high dissociation pressure element 12 in the reservoir 7 is heated at this temperature. As a result, As vapor corresponding to the equilibrium vapor pressure of As of about 1 atm at the melting point temperature of GaAs is generated from the reservoir 7, and the interior chamber 3 is filled with this As vapor.

In this state, the lifting shaft 8 was gradually lowered at a speed of about 1 mm / h. Thereby, the raw material melt in the crucible 6
16 gradually passes through the melting point temperature range mp from its lower side to move to the low temperature side, and accordingly, solidifies from the lower side in contact with the seed crystal 15 to grow a single crystal. A remarkable improvement was observed in the temperature distribution near the melting point during the single crystal growth operation as compared with the conventional one. In particular, the control of the temperature gradient at the growth interface has conventionally been fluctuated by ± 1 to 2 ° C, but in the present apparatus, it was good at within ± 0.1 ° C. Also, each heater 11a-
The output of 11d was also stable, and there was no wobble like in the past.

After all the raw material melt 16 in the crucible 6 is solidified and the single crystal growth is completed, the energization of the heaters 11a to 11d is stopped, and thereafter, when the furnace temperature reaches about 300 ° C. The operation of releasing the argon gas in the pressure vessel 1 to the outside of the furnace is performed, and when the temperature has dropped to about room temperature, the lower lid 1c is lowered to open the pressure vessel 1, and the crucible 6 is recovered to take out the grown crystal. went.

By the above operation, a GaAs single crystal having a length of about 250 mm was obtained. As a result of the stable control of the temperature distribution during the growth of the single crystal as described above, a high quality single crystal with few crystal defects was obtained. It was a crystal. As described above, in the present embodiment, the inter-heater heat insulating material 12a is provided around each of the heaters 11a to 11d.
˜12c, the lower heat insulating material 13, and the outer heat insulating materials 14a to 14d provide stable temperature distribution during single crystal growth, which makes it possible to obtain a high quality single crystal. There is.

That is, the inter-heater heat insulating materials 12a to 12c partition the heaters 11a to 11d from each other, thereby suppressing mutual interference due to heat radiation and gas convection between the heaters, and further, the heaters 11a to 11d. Since the space in each partitioned area and the space between the heat insulating cylinder 2 and each of the heaters 11a to 11d are configured to be as small as possible, the effect of gas convection in each partitioned area and the entire furnace is also exerted. Suppressed. As a result, the independence of control for each heater 11a-11 is improved,
Fluctuations in temperature are greatly suppressed.

In particular, in the above, a single crystal is grown by forming a temperature gradient region A _G which is steeper than the conventional temperature near the melting point temperature. In other words, the steeper the temperature gradient near the melting point temperature range, the smaller the fluctuation of the growth interface with respect to the fluctuation of the temperature (fluctuation). For example, when the temperature fluctuates at 0.5 ° C, the fluctuation of the growth interface is only 0.025 cm when the temperature gradient is 20 ° C / cm, while the fluctuation of the growth interface is 1 ° C / cm when the temperature gradient is 1 ° C / cm. It also fluctuates by 0.5 cm.

Therefore, since the steep temperature gradient is formed in the vicinity of the melting point temperature, re-melting and re-solidifying of the grown crystal is suppressed, and as a result, crystal defects such as dislocations and twins are reduced and the quality is high. Can be obtained as a single crystal. In the present embodiment, in order to form the steep temperature gradient region A _G as described above, a thick inter-heater insulating material 12b having a large thickness is arranged at a position corresponding to the region A _G. Second and third heaters 11b sandwiching the heat insulating material 12b vertically
・ For 11c, mutual interference is sufficiently suppressed. Therefore, the second heater 11b is controlled at the set temperature on the high temperature side of the steep temperature gradient region A _G , and the third heater 11b is adjusted so that the temperature drop occurring in the heat insulating material 12b corresponds to the temperature gradient of the steep temperature gradient region A _G. These heaters 11b that can be accurately controlled independently of each other by deciding and controlling the low temperature side control temperature of 11c
A stable steep temperature gradient region A _G can be formed between 11c.

As described above, in the above heating device 10, the control independence of each heater is improved, the fluctuation of the temperature is suppressed, and the single crystal is formed in the state where the stable steep temperature gradient region A _G is formed. By performing the growth, the fluctuation of the growth interface can be suppressed as small as possible, whereby a high-quality single crystal with few crystal defects such as dislocation density and twins can be obtained. In addition, since seeding can be reliably performed, a single crystal with excellent quality can be manufactured with good reproducibility.

Further, in the above, by generating As vapor in the reservoir 7 and growing a single crystal while controlling the vapor pressure in the internal chamber 3, dissociation of the GaAs raw material in the crucible 6 is suppressed, and the raw material is suppressed. A single crystal of a compound semiconductor having an intended composition can be grown entirely from the melt 16. [Second Embodiment] Next, another embodiment of the present invention will be described with reference to FIG. Note that members having the same functions as the members described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1A shows a heat treatment apparatus configured as a ceramics sintering furnace. In this device,
Around the inner chamber 3, there are four heaters 11 as described above.
A heating device 10 comprising a to 11d is provided. With this heating device 10, a mountain-shaped temperature distribution as shown in FIG. 1B, that is, a sintering temperature region B _S exceeding the sintering temperature sp at a substantially central position in the high-pressure container 1 in the height direction is set within a narrow range. Then, a temperature distribution having steep temperature gradient regions B _G and B _G is formed on both upper and lower sides of the sintering temperature region B _S.

For this reason, the second heater 11b arranged at the height position corresponding to the sintering temperature region B _S is shown in FIG.
As shown in FIG. 5, the heat insulating material between the heaters is formed by shortening the length in the axial direction, and sandwiches the second heater 11b vertically.
12a and 12b are set at height positions corresponding to the steep temperature gradient regions B _G and B _G , respectively, and these heat insulating materials are also provided.
12a and 12b are formed thicker than the heat insulating material 12c between the heaters below. On the other hand, the upper surface of the elevating shaft 5 passing through the lower lid 1c, process material as an object to be heated, for example, Si ₃ N ₄
The pre-sintered body of ceramics such as is held.

When performing sintering of Si ₃ N _{4 with} the above apparatus, the object 21 to be processed is held on the elevating shaft 5 to seal the high-pressure container 1, and the internal chamber 3 is heated to the temperature shown in FIG. The electric power supplied to each of the heaters 11a to 11d is controlled so that the distribution is formed.
During this time, the object to be treated 21 is held with the elevating shaft 5 positioned at the upper limit position so that the lower end portion thereof is positioned above the sintering temperature region B _S. In the sintering of Si ₃ N ₄ , the inside chamber 3 is filled with N ₂ gas, and the outside of the inside chamber 3 is filled with, for example, argon gas at a predetermined high pressure. This suppresses the decomposition of Si ₃ N ₄ , and
An atmosphere state in which deterioration of the heater and the like can be suppressed is formed in the high-pressure container 1.

When the above temperature distribution is reached, the lifting shaft 5 is lowered at a predetermined speed. As a result, the workpiece 21 sequentially passes through the sintering temperature range B _S from the lower end side, and the temperature range B _S
By passing through _S , the unsintered portion 21a is sequentially sintered from the lower end side. In order to precisely control the sintering location by such an operation, it is desirable to narrow the sintering temperature region B _S and make the temperature gradients on both sides thereof as steep as possible. The heating device 10 described above can be stably provided.

The above embodiments are not intended to limit the present invention, and various modifications can be made within the scope of the present invention. For example, in the first embodiment, the vertical Bridgman method (VB
Although the present invention is applied to a single crystal growth apparatus according to the present invention), other types of apparatus such as the horizontal Bridgman method (HB method) can also be configured by applying the present invention.

Further, in the second embodiment, the example in which the object to be treated 21 is lowered and sequentially sintered from the lower end side is described, but conversely, the object to be treated 21 is raised and sintered from the upper end side. It is also possible to do so. Further, the present invention can be configured as a heat treatment apparatus for heat treating the object to be processed from one end side to the other end side in addition to such sintering. Further, a steep temperature gradient is provided so that the high-temperature side heating region and the low-temperature side heating region can be stably formed close to each other in one apparatus, so that the workpiece can be moved from the high-temperature portion to the low-temperature portion. The heat treatment apparatus can be configured to be moved in a short time to thereby impart a quenching effect to the object to be processed.

[0045]

As described above, in the heat treatment apparatus of the present invention, between the heaters arranged in parallel along the outer surface of the internal chamber, the heat insulating material for partitioning the heaters from each other is provided, and A thick heat insulating material is provided at a position corresponding to a steep temperature gradient region of the temperature distribution formed in the chamber. As a result, mutual interference due to heat radiation and heat convection between the heaters is reduced, control independence is improved, and a steep temperature gradient can be formed accurately and stably. As a result, for example, in a single crystal manufacturing apparatus, single crystal growth can be performed in a state where there is little fluctuation at the growth interface, and as a result, a good quality single crystal with reduced crystal defect density can be obtained.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG.
(a) is a schematic vertical cross-sectional view showing a heat treatment apparatus configured as an apparatus for producing a compound semiconductor single crystal, and (b) is a graph showing an in-apparatus temperature distribution during a single crystal growth operation.

2A and 2B show another embodiment of the present invention, wherein FIG. 2A is a schematic vertical sectional view showing a heat treatment apparatus configured as a ceramics sintering furnace, and FIG. It is a graph which shows the temperature distribution in an apparatus at the time of connection.

FIG. 3 is a schematic vertical sectional view showing an example of a conventional single crystal manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-pressure container (furnace body) 3 Internal chamber 5 Elevating shaft (moving means) 6 Crucible (raw material storage container) 7 Reservoirs 11a to 11d Heaters 12a to 12c Heater insulating material between heaters

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Okada 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Co., Ltd. Kobe Research Institute (72) Inventor Takeho Kawanaka Takatsuka, Nishi-ku, Kobe-shi, Hyogo Prefecture 1-5-5 stand, Kobe Steel, Ltd. Kobe Research Institute

Claims (5)

[Claims] 1. A heat treatment apparatus in which a plurality of heaters are arranged in parallel along an outer surface of an internal chamber provided in a furnace body, and a predetermined temperature distribution is formed in the internal chamber by energizing these heaters. A heat insulating material extending between adjacent heaters to a position close to the outer surface of the internal chamber is interposed between the respective heaters, and a specific heat insulating material having a thickness that substantially fills the gap between the adjacent heaters is provided. A heat treatment device characterized in that its thickness is made thicker than that of the other heat insulating material and is provided at a position corresponding to a steep temperature gradient region where a temperature gradient is locally large in the temperature distribution. . 2. The heat insulating material is BN, SiC, Si ₃ N ₄ , AlN, Al ₂ O ₃ , SiO
_2. The heat treatment apparatus according to claim 1, which is made of a ceramic material such as ₂ , ZrO ₂ or a carbon material. 3. A moving means for moving an object to be heated within the internal chamber is further provided.
Or the heat treatment apparatus according to 2. 4. A raw material storage container for storing as a material to be heated a raw material that grows as a single crystal by solidifying the raw material melt from the side in contact with the seed crystal, wherein the steep temperature gradient region is the melting point of the single crystal. The heat treatment apparatus according to claim 3, wherein the heat treatment apparatus is set in a temperature region including. 5. When a raw material for crystal growth of a III-V group compound semiconductor or a II-VI group compound semiconductor is used as the raw material, vapor of a high dissociation pressure element in the constituent elements is generated during crystal growth. The heat treatment apparatus according to claim 4, wherein a reservoir for maintaining a predetermined vapor pressure in the inner chamber is further provided in the inner chamber.