JPH0826879A - Single crystal pulling apparatus for compound semiconductor and method for producing compound semiconductor single crystal - Google Patents

Abstract

(57) [Summary] [Object] To provide a single crystal pulling apparatus and a manufacturing method devised so as to surely suppress an increase in the surface temperature of a single crystal even when pulling a single crystal having a long pulling length. [Constitution] The present apparatus 10 includes a crucible 12 for containing a raw material composed of two or more kinds of elements including a high dissociation pressure element, a heater 14 for heating the raw material in the crucible into a raw material melt, and elevating and lowering it.
And a rotatable upper shaft 30. This apparatus comprises a cooler 40 arranged above the crucible so as to surround the lower end of the single crystal T for cooling the single crystal to be pulled,
Supplying means 42 and 44 for supplying the refrigerant to the cooler are provided. A seed crystal S is attached to the lower end of the upper shaft 30, and a single crystal of a compound semiconductor whose crystal orientation matches the seed crystal is pulled out from the raw material melt. At that time, the surface temperature of the single crystal is adjusted by adjusting the output of the heater arranged in the vicinity of the cooler in accordance with the single crystal pulling length according to a program created in advance while cooling the single crystal with the cooler. Control to a predetermined temperature. This makes it possible to obtain a good quality single crystal without surface roughness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention stores a raw material containing a high dissociation pressure element in a crucible arranged in a high-pressure chamber, heats and melts it with a heater to form a raw material melt, and then melts a seed crystal into the raw material. The present invention relates to a single crystal pulling apparatus for a compound semiconductor and a method for producing a compound semiconductor single crystal, which is immersed in a liquid and pulls a single crystal whose crystal orientation matches a seed crystal from a raw material melt.
Here, the high dissociation pressure element is, for example, As or P.

[0002]

2. Description of the Related Art A typical compound semiconductor made of two or more kinds of elements including a high dissociation pressure element is a GaAs compound semiconductor. Compound semiconductors such as GaAs are widely used in ICs, lasers, diodes and the like, taking advantage of their higher electron mobility than silicon, and the demand for them has been increasing rapidly in recent years. Therefore, in order to meet the increasing demand, a single crystal of a compound semiconductor having a large diameter and a long crystal length is required, and research on an apparatus and a method for efficiently pulling such a compound semiconductor single crystal is actively conducted. It is being appreciated.

By the way, conventionally, a single crystal of a compound semiconductor has been manufactured by a compound crystal single crystal pulling apparatus (hereinafter simply referred to as a pulling apparatus) as shown in FIG. The conventional pulling apparatus includes a crucible 12 for containing raw materials, one or a plurality of heaters 14 for heating and melting the raw materials in the crucible 12, a pressure vessel 16 for storing them, and a single crystal pulling mechanism. 18 and a crucible rotation / elevation mechanism 20. The crucible 12 and the heater 14 are installed inside a tubular carbon member 22 called a hot zone arranged in the pressure vessel 16. The crucible rotation / elevation mechanism 20 includes a lower shaft 24 that fixes the crucible 12 at the upper end, and a rotating device 26 that is connected to the lower end of the lower shaft 24.
And a lifting device (not shown). The crucible 12 is driven by a rotating device 26 via a lower shaft 24 to rotate, and is also driven by an elevating device (not shown) to move up and down integrally with the rotating device 26.

On the other hand, the single crystal pulling mechanism 18 includes a seed holder 28 for mounting a seed crystal (seed), an upper shaft 30 for fixing the seed holder 28 at its lower end, and a separate upper end for connecting the upper shaft 30. The rotating device 32 and another lifting device (not shown). The seed holder 28 is driven by a rotating device 32 via an upper shaft 30 to rotate, and is driven by another elevating device (not shown) to move up and down integrally with the rotating device 32.

A raw material containing a high dissociation pressure element is housed in the crucible 12, and the raw material is melted by heating the raw material to a melting point of the compound semiconductor with a heater 14 to obtain a raw material melt R. On the other hand, the seed crystal S is attached to the seed holder 28, and the seed crystal S is dipped in the raw material melt R to make it fit, and then the upper shaft 30 is pulled up to manufacture the single crystal T. At this time, in order to prevent the high dissociation pressure element such as As from scattering from the raw material melt, the B ₂ O ₃ melt is used as the sealant H to coat the raw material melt R, and further, the Ar 2 A pressure of about 10 atm is applied to the surface of the melt with an active gas. In this way, for example, with a crystal size of φ4 ”, 120
A single crystal with a length of mm is produced.

By the way, the surface temperature of the crystal gradually rises as the crystal is pulled up. For example, taking the production of GaAs single crystal as an example, when a GaAs single crystal with a crystal diameter of 4 inches and a length of 200 mm is produced from 15 kg of raw material, the crystal directly above the B ₂ O ₃ melt used as a sealant. As shown by the solid line in FIG. 7, the surface temperature is about 950 ° C. at the initial stage of crystal pulling, but becomes higher than 950 ° C. on the way and becomes about 1050 ° C. at the final stage of crystal pulling. It is considered that the raw material melt in the crucible decreases with the pulling of the crystal, and the heat capacity increases as the mass of the crystal increases, so that the surface temperature of the crystal rises. 10 (a), 10 (b) and 10 (c) show that the raw material melt decreases as the pulling length of the single crystal becomes longer in the initial stage of crystal pulling, in the intermediate stage and in the final stage of crystal pulling. Respectively, and the temperature indicated by the solid line in FIG. 7 is the temperature at point A in FIG.

The surface temperature of the GaAs crystal being pulled is 105
If it exceeds 0 ° C, the Ga-As bond is broken and As is released from the crystal surface. The remaining Ga has a melting point of about 3
Since it is 0 ° C, it liquefies and flows out from the crystal surface. When this phenomenon progresses, a depression is generated on the GaAs surface.
This is a defect on the surface of the crystal, which is generally called rough surface of the crystal, and crystal defects such as lamella twin and polycrystallization occur from the rough surface portion, and a uniformly grown single crystal cannot be obtained.

Usually, Ar gas is introduced to maintain a high pressure in the pressure vessel, thereby suppressing the scattering of the element having a high dissociation pressure. Further, as a means for preventing the surface temperature of the single crystal from rising, Ar is used. A gas having a higher thermal conductivity than the gas, for example, N ₂ gas is mixed with Ar gas, or the pressure in the pressure vessel during pulling of the single crystal is made higher than the normal pressure of 10 atm to cause convection of gas. Has been proposed in recent years.

[0009]

However, even if N ₂ gas is mixed as a different gas to suppress the rise of the surface temperature, the effect is that the pulling length of the single crystal is 180
If the length is less than mm, and the length is more than that, the rise of the crystal surface temperature cannot be suppressed and the skin becomes rough. In addition, there is a problem that the nitrogen compound adheres strongly to the surface of the crystal. In addition, the method of increasing the pressure in the pressure vessel has a drawback that the temperature environment of the crystal growth field fluctuates as a whole due to the change in pressure, and therefore the overall temperature condition of the crystal growth field is controlled to a predetermined temperature. It was actually difficult to do so, and it was difficult to put it into practical use. On the other hand, in order to improve productivity, the pulling length of the single crystal is required to be longer than the conventional 170 mm, 200 mm, and further 400 mm, 5
In the era where 00 mm is required, the development of a means for surely suppressing the rise of the surface temperature of a single crystal is the first step to meet this demand.

Therefore, the present invention provides a single crystal pulling apparatus and a manufacturing method devised so as to surely suppress an increase in the surface temperature of a single crystal even when pulling a single crystal having a long pulling length. It is an object.

[0011]

As another means to replace the conventional method, the present inventor has provided a cooler in a pressure vessel,
We focused on cooling the single crystal by flowing a coolant such as cold water, thereby suppressing the rise of the surface temperature of the single crystal. However, no studies and proposals have been made so far in which a cooler is provided in the pressure vessel and an increase in the surface temperature of the crystal is suppressed by the cooling action of the cooler. Therefore, the present inventor has provided a cylindrical cooler with an arrangement so as to surround the single crystal being pulled up, and after repeated experiments, the surface temperature of the single crystal can be brought to a desired temperature simply by flowing a cooling medium. It turned out to be extremely difficult to control in practice. It is virtually impossible to design the cooler so that the surface temperature of the single crystal is exactly the desired temperature, and even if the flow rate of the refrigerant or the inlet temperature of the refrigerant is adjusted to control the cooling action, This is because it is difficult to control the cooling action in practice because of problems such as poor response to the change in surface temperature of the single crystal. Therefore, the present inventor has completed the present invention by focusing on the temperature control separately from the cooling action.

In order to achieve the above object, a single crystal pulling apparatus for a compound semiconductor according to the present invention is attached to an upper shaft and a lower shaft which can be raised and lowered and rotatable, and an upper end of the lower shaft, and contains a high dissociation pressure element. A compound that comprises a crucible containing a compound semiconductor raw material and a heater arranged around the crucible, attaches a seed crystal to the lower end of the upper shaft, and pulls a single crystal whose crystal orientation matches the seed crystal from the raw material melt. In a semiconductor single crystal pulling apparatus, a cooler arranged above the crucible so as to surround at least a part of the periphery of the single crystal for cooling the single crystal being pulled, and a coolant is supplied to the cooler. And a heater, the heater being composed of a plurality of heaters arranged above and below, and the heater closer to the cooler being of variable output type, while cooling the single crystal by the cooler The output of the variable heater It is characterized by controlling the surface temperature of the single crystal to a predetermined temperature by adjusting in accordance with the single crystal pulling length according order created programs.

The required cooling capacity Q of the cooler for cooling the single crystal is as follows: density of the single crystal is Bg / cm ³ , specific heat of the single crystal is Ckcal / g · ° C, diameter of the single crystal is Dcm, The pulling rate of the single crystal is Fcm / Hr, the maximum temperature of the single crystal when the sealing agent H is discharged is T ° C, and the predetermined surface temperature of the single crystal is T _S °.
Letting C be, Q = π · (D / 2) ² · F · B · C · (T−T _S ) kcal / Hr (1). The cooler used in the present invention is a cooler having a cooling capacity equal to or higher than the cooling capacity Q obtained in the above formula (1), and is excessively cooled by heating with a heater while operating the cooler under predetermined design conditions. Regulates temperature by offsetting capacity. The refrigerant flowing in the cooler is a known refrigerant, and for example, cold water, a cooling liquid metal such as mercury or gallium, or the like can be used.

The program preset in the present invention shows the relationship of decreasing the output of the heater according to the pulling length of the single crystal under the cooling action of a certain condition. Using the above equipment and the dummy crystal, a simulation experiment of pulling the single crystal was performed under the conditions that match the actual operating conditions, and based on the obtained data, the surface temperature of the single crystal was adjusted to the predetermined temperature by the heater. The output is defined. As will be described later, the surface temperature of the single crystal is monotonically decreasing as it goes upward, and since it is effective to regulate the surface temperature directly above the sealant melt to prevent crystal defects, The cooler is preferably arranged above the crucible and at a position as close to the surface of the sealant melt as possible to cool the lower end of the single crystal.

The cooler used in the present invention is a cooler having a known structure, for example, a coil-type cooler in which a cooling pipe is wound in a spiral shape and a refrigerant is allowed to flow through the cooling pipe. Multi-tube cooler with a large number of cooling tubes arranged in the vertical direction, a cylindrical cooler that allows a refrigerant to flow in an annular space formed by double cylinders, and a cooling tube or fins with fins on the cylindrical surface Various coolers, such as coolers, can be used. The cooler is preferably configured to surround the entire circumference of the single crystal, but since the single crystal is pulled while rotating, if the cooler is arranged so as to surround at least a part of the single crystal. The effect of the present invention can be achieved.

Another apparatus for pulling a single crystal according to the present invention comprises an upper shaft and a lower shaft which can be raised and lowered and rotated, a crucible which is attached to an upper end of the lower shaft and which contains a compound semiconductor raw material containing a high dissociation pressure element, With a heater arranged around the crucible, a seed crystal is attached to the lower end of the upper axis, and a single crystal pulling apparatus for a compound semiconductor that pulls a single crystal whose crystal orientation matches the seed crystal from the raw material melt, A cooler arranged above the crucible so as to surround at least a part of the periphery of the single crystal for cooling the single crystal being pulled, a supply means for supplying a refrigerant to the cooler, and a single crystal lower end portion. A temperature measuring device capable of measuring the surface temperature and a control device are provided, and further, the heater is composed of a plurality of heaters arranged vertically, and the heater closer to the cooler has a variable output type, and the temperature is measured. Based on the temperature measured by the instrument Adjust the output of the force variable heater by the controller, it is characterized by controlling the surface temperature of the single crystal lower end portion to a predetermined temperature.

The temperature measuring device used in the present invention is a thermometer capable of measuring the temperature of a high temperature region around a single crystal, and is preferably a radiation thermometer using a sapphire rod as an infrared waveguide.

A preferred embodiment of the present invention is characterized in that a heater is interposed between the single crystal and the cooler separately from the heater for heating the crucible, and the heater has a variable output type. .

The method for producing a single crystal according to the present invention is
A cooler arranged above the crucible so as to surround at least a part of the periphery of the single crystal being pulled, a supply means for supplying a refrigerant to the cooler, and a temperature measuring device capable of measuring the surface temperature of the lower end of the single crystal. While pulling the compound semiconductor single crystal using B ₂ O ₃ as a sealant, the single crystal pulling apparatus for compound semiconductor is provided with By adjusting the output of the heater arranged near the cooler, the surface temperature of the single crystal immediately above the melt of the sealant was maintained at 900 ° C to 1,05 ° C during pulling up of the single crystal.
It is characterized by controlling at 0 ° C, preferably 950 to 1,050 ° C.

[0020]

According to the first aspect of the invention, the output of the heater arranged in the vicinity of the cooler is created in advance in order to offset the excessive cooling amount while cooling the single crystal with a constant cooling capacity by the cooler. The surface temperature of the single crystal is controlled to a predetermined temperature by adjusting the pulling length of the single crystal according to a program. According to the invention of claim 2, in order to offset the excessive cooling amount while cooling the single crystal with a constant cooling capacity by the cooler, the temperature measuring device capable of measuring the surface temperature of the lower end portion of the single crystal and the output of the heater are provided. The temperature of the single crystal is controlled to a predetermined temperature by adjusting the output of a heater arranged near the cooler based on the measured temperature of the lower end of the single crystal. In claims 1 and 2, since the output of the heater, which has a response much faster than that of the method of directly adjusting the output of the cooler, is adjusted, the surface temperature of the single crystal can be controlled easily and precisely. it can. By controlling the surface temperature, scattering of an element having a high dissociation pressure is prevented, and roughening of the single crystal is prevented. In the invention of claim 3, since the adjustment is made by the heater provided separately from the main heater for heating the crucible, the surface temperature of the lower end portion of the single crystal can be precisely controlled without affecting the action of the main heater.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the accompanying drawings. Example 1 FIG. 1 is a sectional side view showing the configuration of Example 1 of a compound semiconductor single crystal pulling apparatus (hereinafter simply referred to as a pulling apparatus) according to the present invention, and FIG. (b) (c) is a perspective view of a cooler, respectively. Of the parts and parts shown in FIG. 1, those which are the same as those shown in FIG. In addition to the configuration described with reference to FIG. 9, the pulling device 10 of the present embodiment includes a cooler 40, a supply pipe 42 that supplies a refrigerant to the cooler 40, and an exhaust pipe 44 that discharges the refrigerant from the cooler 40. It has and. Further, the heater 14 is composed of three heaters 14A, B and C arranged vertically, and at least the upper heater 14A can control its output independently of the other heaters 14B and C. There is.

The cooler 40 is the coil type cooler illustrated in FIG. 2 (a), and is provided immediately above the crucible 12 so as to surround the lower end of the single crystal. This allows the single crystal to be cooled in the cooler immediately after exiting the sealant melt. For example, when a crucible having a crucible diameter of 250 mm is used, the cooler 40 is preferably arranged about 50 mm to 150 mm above the crucible 12. Figure 2
The cooler shown in (a) is a coil type cooler in which a cooling pipe 48 is wound in a spiral shape, the upper end of the coil is connected to the supply pipe 42 and the lower end to the discharge pipe 44, and the refrigerant enters from the upper end in the direction of the arrow. , Discharged from the bottom. As another example, the cooler shown in FIG. 2 (b) is a double-cylindrical cooler in which a partition wall 50 (indicated by a broken line) is provided in the annular flow path formed inside, and the refrigerant is in the partition wall. Flow in the direction of the arrow. The cooler shown in FIG. 2C is composed of upper and lower ring headers 52 and 54 and a large number of cooling pipes 48 provided therebetween, and the refrigerant flows down in the cooling pipes 48 as indicated by arrows.

In order to increase the heat transfer area and improve the heat transfer efficiency, fins 56 may be provided in the cooling pipe 48 of the cooler as shown in FIG. FIG. 4 is a cross-sectional view showing another means for increasing the heat transfer area to increase the heat transfer efficiency.
In FIG. 4, the cooling pipe 4 of the coil type cooler shown in FIG.
A cylindrical plate 58 is attached to the inner side of 8 to increase the heat transfer area. Although it depends on the length of the crystal to be pulled, the cooler 40 used in the present embodiment is a cooler having a capacity which is approximately 10% or more larger than the required cooling capacity Q calculated by the above-mentioned formula 1, and the surface temperature of the single crystal. The output of the heater 14 </ b> A adjacent to the cooler 40 is adjusted so that is cooled to a predetermined temperature.

In the present embodiment, the single crystal is controlled so that the surface temperature immediately above the encapsulant becomes 950 ° C. or higher below the temperature shown by the broken line in FIG. 7 as the pulling length of the single crystal becomes longer. A program is created in which the relationship between the pull-up length and the output of the heater 14A is predetermined, and the output of the heater 14A is adjusted according to the program.

Embodiment 2 Embodiment 1 is a heater 14A according to a predetermined program.
In this embodiment, the output of the heater 14A is adjusted while measuring the crystal surface temperature online. As shown in FIG. 5, in the pulling up apparatus 60 of the present embodiment, in the configuration of the first embodiment, the thermometer 62 for measuring the temperature around the single crystal and the output of the heater 14A are adjusted based on the measured temperature. The control device 64 controls the temperature around the single crystal.

In this embodiment, a sapphire rod type radiation thermometer is used as the thermometer 62 in consideration of the high temperature of the temperature measuring region.
Is used as. In this radiation thermometer, the tip of the sapphire rod 66 is brought close to the surface of the single crystal directly above the B ₂ O ₃ melt, the infrared light is taken out of the system by using the sapphire rod 66 as a waveguide, and the infrared light is spectrally analyzed. Analyzing B ₂ O
₃ Measure the crystal surface temperature directly above the melt. As the thermometer 62, for example, a system using a light pipe sensor (proximity type) sold by Japan Energy Co., Ltd. can be used. The control device 64 uses the output device 68 of the heater 14A.
Is adjusted to feedback control the surface temperature of the lower end of the single crystal so as to reach a predetermined temperature. According to this method, since the surface temperature of the crystal being pulled can be controlled in real time, the surface temperature of the single crystal can be controlled more easily and strictly.

Embodiment 3 FIG. 6 is a side sectional view showing the main part of Embodiment 3 of the lifting apparatus according to the present invention. In addition to the configurations of the lifting device 10 of the first embodiment and the lifting device 60 of the second embodiment, the lifting device 70 of the present embodiment further includes a heater 1 for heating the crucible inside the cooler 40.
In addition to 4A, a heater 72 for temperature control is provided. By adjusting the output of the heater 72, the cooling action of the cooler 40 can be finely adjusted and the surface temperature of the single crystal can be maintained at a predetermined temperature without affecting the heating of the crucible 12.

Experimental Example First, a dummy crystal and a conventional pulling apparatus shown in FIG. 9 were used, the growth conditions were simulated, and the crystal surface immediately above the B ₂ O ₃ melt when the single crystal was not cooled. The temperature was measured. It has crystal lengths of 0, 30, 120, and 200 mm, respectively.
Then, using a dummy crystal with a thermocouple arranged on the surface of the crystal,
The surface temperature of the dummy crystal was measured by setting the simulation conditions so that the amount of the raw material melt and the heater temperature when the single crystal became the length corresponded to the actual pulling condition. The result is shown in Figure 7.
Is indicated by a solid line. From this figure, when the crystal length of the single crystal is about 180 mm or more, the crystal surface temperature directly above the B ₂ O ₃ melt exceeds 1050 ° C. Therefore, it is understood that crystal defects are generated when the pulling length of the single crystal exceeds 180 mm.

On the other hand, when the raw material is completely melted in the crucible 12, the temperature distribution above the crucible before pulling up is
It is as shown in FIG. Therefore, in order to produce a good quality single crystal, it is necessary to set the surface temperature of the single crystal directly above the B ₂ O ₃ melt to 900 ° C. or higher, preferably 950 ° C. or higher. Further, from the results of the above experiment, it is necessary that the surface temperature is 1050 ° C or lower. 8, the B ₂ O ₃ above find that monotonically temperature decreases, in order to prevent the occurrence of crystal defects it is understood that it is sufficient to regulate the surface temperature of the B ₂ O ₃ melt directly above the single crystal.

Therefore, in order to obtain a single crystal free from rough skin, the surface temperature of the single crystal directly above the B ₂ O ₃ melt is 900 ° C.
It is necessary that the temperature is 1050 ° C or lower. Then, using the pulling apparatus 10 of Example 1, 10 l / min of cooling water was made to flow through the cooler 40, and the output of the heater 14A was gradually lowered as the crystals became longer, while dummy crystals were formed in the same manner as described above. The simulated experiment used was performed to measure the surface temperature. As a result of adjusting the output of the heater 14A by trial and error, even if the crystal length is 200 mm, as shown by the dotted line in FIG. 7, the surface temperature immediately above the B ₂ O ₃ melt of the single crystal is 950 ° C. during pulling. Above the above, the temperature could be controlled to 1050 ° C or lower. Actually, the surface temperature was 1030 ° C when the crystal length was 200 mm. The operating conditions at this time of the pulling apparatus 10 were created as a program, including the conditions of the cooler 40, the relationship between the pulling length of the single crystal and the output of the heater 14A, and the like.

Next, the pulling apparatus 10 of Example 1 was used to pull up a single crystal, and the performance of the pulling apparatus was evaluated. First, Ga and As were mixed so that the composition ratio of the single crystal after pulling was 1: 1 to prepare a compound semiconductor raw material of about 15 kg. This raw material was placed in a crucible 12 made of pBN (boron nitride) having a diameter of 25 cm, and the raw material was heated to a melting point of GaAs (1238 ° C.) by a heater 14 to be melted to form a melt R. At this time, in order to prevent the scattering of As, B ₂ O ₃ is used as the sealant H to cover the raw material melt, and the pressure vessel 16
Ar gas was introduced thereinto to adjust the internal pressure to 70 kg / cm ² g.
Then, after the pressure is set to 10 kg / cm ² g, a 6 mm square GaAs seed crystal S is attached to the lower end of the upper shaft 30 via the seed holder 28, and the seed crystal S is dipped in the raw material melt R to sufficiently adapt it. After the removal, the upper shaft 30 was pulled up at a pulling rate of 10 mm / Hr. At this time, the rotation speeds of the upper shaft 28 and the lower shaft 22 are
The speed was 10 and 20 rpm, respectively.

According to the program described above, the single crystal was pulled while adjusting the output of the heater 14A according to the pulling length of the single crystal. As a result, during the pulling of the single crystal, the surface temperature was 950 ° C or higher and 1050 ° C or lower over the entire length of 200 mm. As a result, a GaAs single crystal having a diameter of 4 inches and a crystal length of 200 mm, which was not roughened, could be pulled out from the raw material melt R.

According to the present lifting devices 10, 60 and 70,
Unlike the conventional method of changing the gas pressure and the type of gas, the gas environment or pressure of the crystal growth field is not changed, so that the surface temperature of the single crystal can be easily controlled and a good quality single crystal can be manufactured.

[0034]

According to the structure of the present invention, the surface temperature of the single crystal is controlled by adjusting the output of the heater while operating the cooler under constant conditions. The output of the heater can be adjusted more quickly and precisely than the method of directly adjusting the output of the cooler as a method of adjusting the cooling capacity of the cooler, so the surface temperature of the single crystal can be easily adjusted. In addition, it is possible to control accurately, thereby preventing the dissociation of the high dissociation pressure element and manufacturing a single crystal without rough skin. By applying the device and the manufacturing method of the present invention to control the surface temperature to a predetermined temperature, it is currently difficult to manufacture 200 mm.
A longer single crystal can be manufactured without crystal defects.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view showing the configuration of Example 1 of a compound semiconductor single crystal pulling apparatus according to the present invention.

2 (a), (b) and (c) are perspective views of coolers of different types.

FIG. 3 is a partial cross-sectional view of a cooling pipe having fins implanted therein.

FIG. 4 is a sectional view of a cooler provided with a cylindrical wall.

FIG. 5 is a cross-sectional side view showing the configuration of Example 2 of the apparatus for pulling a single crystal of a compound semiconductor according to the present invention.

FIG. 6 is a sectional side view showing a configuration of a main part of a third embodiment of a compound semiconductor single crystal pulling apparatus according to the present invention.

FIG. 7 is a graph showing the relationship between the crystal length of a single crystal and the crystal surface temperature directly above the sealant.

FIG. 8 is a graph showing the crystal surface temperature along the longitudinal direction of a single crystal.

FIG. 9 is a sectional side view showing a configuration of a conventional single crystal pulling apparatus.

10 (a), (b) and (c) are explanatory views showing a decrease in melt in the crucible as the single crystal is pulled up.

[Explanation of symbols]

 10 Example 1 of the pulling apparatus according to the present invention 12 Crucible 14 Heater 16 Pressure vessel 18 Lifting mechanism 20 Crucible rotation / elevating mechanism 22 Carbon member 24 Lower shaft 26 Rotating device 28 Seed holder 30 Upper shaft 32 Other rotating device 40 Cooler 42 Supply pipe 44 Discharge pipe 48 Cooling pipe 50 Partition walls 52, 54 Ring header 56 Fin 58 Cylindrical plate 60 Example 2 of the pulling device according to the present invention 62 Thermometer 64 Control device 66 Sapphire rod 68 Heater output device 70 Example 3 of pulling apparatus according to the present invention 72 Heater for temperature control

Claims (4)

[Claims] 1. An upper shaft and a lower shaft which can be raised and lowered and rotated, a crucible which is attached to an upper end of the lower shaft and which contains a compound semiconductor raw material containing a high dissociation pressure element, and a heater which is arranged around the crucible. Equipped with a seed crystal at the lower end of the upper axis, in a compound semiconductor single crystal pulling apparatus for pulling a single crystal whose crystal orientation matches the seed crystal from the raw material melt, in order to cool the single crystal being pulled A plurality of heaters arranged above and below the crucible so as to surround at least a part of the periphery of the single crystal; and a supply means for supplying a refrigerant to the cooler; The output of the heater with variable output is adjusted according to the pulling length of the single crystal according to the program created in advance while cooling the single crystal with the cooler. What to do An apparatus for pulling a single crystal of a compound semiconductor, characterized in that the surface temperature of the single crystal is controlled to a predetermined temperature by means of. 2. An upper shaft and a lower shaft which can be raised and lowered and rotated, a crucible which is attached to an upper end of the lower shaft and which stores a compound semiconductor raw material containing a high dissociation pressure element, and a heater which is arranged around the crucible. Equipped with a seed crystal at the lower end of the upper axis, in a compound semiconductor single crystal pulling apparatus for pulling a single crystal whose crystal orientation matches the seed crystal from the raw material melt, in order to cool the single crystal being pulled A cooler arranged above the crucible so as to surround at least a part of the periphery of the single crystal, a supply means for supplying a refrigerant to the cooler, and a temperature measuring device capable of measuring the surface temperature of the lower end of the single crystal, and control A heater having a plurality of heaters arranged above and below the heater, and the heater closer to the cooler has an output variable type, and an output variable heater based on the temperature measured by the temperature measuring device. Control the output of An apparatus for pulling a single crystal of a compound semiconductor, wherein the surface temperature of the lower end portion of the single crystal is controlled to a predetermined temperature by adjusting the temperature of the single crystal. 3. The heater according to claim 1 or 2, wherein a heater is interposed between the single crystal and the cooler separately from the heater for heating the crucible, and the heater has a variable output type. An apparatus for pulling a single crystal of a compound semiconductor as described. 4. A cooler arranged above the crucible so as to surround at least a part of the periphery of the single crystal being pulled,
A single crystal pulling apparatus for a compound semiconductor, which comprises a supply means for supplying a coolant to a cooler and a temperature measuring device capable of measuring the surface temperature of the lower end of the single crystal, is used, and B ₂ O ₃ is used as a sealant. When pulling up the compound semiconductor single crystal by pressing, the output of the heater placed near the cooler is adjusted while cooling the single crystal under pressure, and the single crystal immediately above the melt of the sealant is adjusted. The surface temperature is 900 ° C. to 1,050 ° C., preferably 950 to 1, over the course of pulling the single crystal.
A method for producing a GaAs single crystal, characterized by controlling at 050 ° C.