JPH0570276A - Device for producing single crystals - Google Patents

Abstract

PURPOSE:To provide a device for producing single crystals of a good quality with low dislocation density by increasing the accuracy of temp. control for each heater in a device for controlling temp. distribution in a growth furnace using plural heaters to grow single crystals. CONSTITUTION:In a device 70 having plural adjacent heaters 1-10 to produce single crystals by the VGF method, shield plates 11-19 in the shape of a hollow disc for the partitioning the heaters from each other are further provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling a temperature distribution in a growth furnace to control a single crystal, and in particular,
Apparatus for producing III-V group compound semiconductor single crystal such as GaAs, GaP, GaSb, InAs, InP and InSb, and II-VI group compound semiconductor single crystal such as CdTe, Hg _1-X Cd _X Te and ZnSe Regarding

[0002]

2. Description of the Related Art Horizontal Bridgman method (HB method), vertical Bridgman method (VB method), solidification method with horizontal temperature gradient (HG)
F method) and the vertical temperature gradient solidification method (VGF method),
Since it is necessary to strictly control the temperature distribution in the growth furnace, a multi-stage heater structure in which a plurality of heaters are arranged adjacent to each other has been adopted. FIG. 4 shows an example of a conventional device for performing the VGF method. In the VGF device 80, a heat insulating cylinder 58 is provided in the chamber 55, and a quartz tube 25 is provided in the heat insulating cylinder 58, surrounded by ten adjacent heaters 1 to 10. In the quartz tube 25, the crucible 20 having a thin tip is placed. A seed crystal 21 is provided at the tip of the crucible 20.
Is attached, and the melt 23 is housed above it so that the single crystal 24 grows from the seed crystal 21. Also, crucible 2
The upper opening of 0 is covered with a lid 22 to prevent the surface of the melt 23 from being cooled by radiation. A reservoir 63 is provided below the quartz tube 25, and the high dissociation pressure component 26 is stored therein. The quartz tube 25 is sealed, and the vapor pressure of the high dissociation pressure component in the quartz tube 25 is adjusted by controlling the temperature of the reservoir 63 portion. In the apparatus configured as described above, by adjusting the outputs of the heaters 1 to 10, the temperature is gradually decreased from the seed crystal side to grow a single crystal.

On the other hand, in the case of the liquid capsule pull-up method (LEC method), the number of heaters is generally 2 to 3, but it is considered that the number of heaters will be further increased in the future. In particular, in the growth of compound semiconductor single crystal by the pulling method, it is necessary to reduce the temperature gradient in the growth axis direction in order to keep the dislocation density of the growing single crystal low, and to control the output of each heater using a multi-stage heater, The target temperature gradient must be created accurately.

[0004]

In order to grow a good quality single crystal in the crystal growth method described above, it is necessary to precisely control the temperature distribution in the growth furnace. However, in the conventional single crystal manufacturing apparatus, the accuracy of temperature control by each heater is limited due to thermal convection and radiation from a plurality of heaters adjacent to each other.

An object of the present invention is to provide an apparatus capable of producing a good quality crystal having a low dislocation density with good reproducibility by improving the accuracy of temperature control by a heater in a single crystal producing apparatus. ..

[0006]

The apparatus for producing a single crystal according to the present invention is characterized in that an apparatus having a plurality of heaters adjacent to each other is further provided with a shielding member for partitioning each heater.

The shielding member according to the present invention includes carbon, quartz, pyrolytic boron nitride (PBN),
It can be formed of a material such as boron nitride (BN), SiC, Si ₃ N ₄ and AlN, and a material in which carbon is coated with at least one of quartz, PBN, BN, SiC, Si ₃ N ₄ and AlN. Can be formed more.

The device according to the invention is particularly suitable for GaAs, G
aP, GaSb, InAs, InP and InSb, etc.
III-V compound semiconductor single crystal and CdTe,
Hg _1-XCd_XII-VI genus such as Te and ZnSe
It can be used as a device for manufacturing compound semiconductor single crystals.
It

The apparatus according to the present invention can be an apparatus for producing a single crystal according to the Czochralski method, LEC method, HB method, VB method, HGF method, and VGF method.

[0010]

According to the present invention, in a single crystal manufacturing apparatus having a plurality of heaters, since each heater is partitioned by the shielding member, the convection and radiation from the adjacent heaters are blocked by the shielding member. Therefore, the accuracy of temperature control by each heater can be improved.
If the accuracy of temperature control is improved, the solid-liquid interface in crystal growth can be controlled more strictly, and twin crystals, lineage, freezeout, etc. can be suppressed and a single crystal with a low dislocation density can be manufactured. Like

[0011]

[Example] 1. Example of Application to VGF Method FIG. 1A shows a specific example in which the present invention is applied to an apparatus of the VGF method. In the VGF device 70, a heat insulating cylinder 58 is provided in the chamber 55, and the quartz tube 2 is provided in the heat insulating cylinder 58.
5 are provided. Around the quartz tube 25, adjacent 10
Individual heaters 1 to 10 are arranged. Further, between the heaters, shielding plates 11 to 19 in which carbon is coated with PBN are provided so as to be attached to the heat insulating cylinder 58. The shielding plates 11 to 19 are disk-shaped with holes formed therein as shown in FIG. In the quartz tube 25, the crucible 20 having a thin tip is placed. A seed crystal 21 is attached to the tip of the crucible 20, and the seed crystal 2
1 so that a single crystal 24 grows above the raw material melt 2
3 are accommodated. Further, the upper opening of the crucible 20 has a lid 22.
The surface of the raw material melt 23 is covered with, and is prevented from being cooled by radiation. A reservoir 63 is provided below the quartz tube 25 to contain the high dissociation pressure component 26. Quartz tube 25
Is sealed, and the vapor pressure of the high dissociation pressure component in the quartz tube 25 is adjusted by controlling the temperature of the reservoir 63. Instead of the quartz tube 25, an airtight container made of a material such as PBN, pyrolytic graphite (PG), PBN coated carbon, PG coated carbon and molybdenum may be used.

Using the device configured as described above, V
A 3 inchφ non-doped GaAs single crystal was grown by the GF method. In growing the crucible 20, a PBN crucible having an upper inner diameter of 85 mm and a lower inner diameter of 80 mm was used. The lower part of the crucible was formed into a conical shape, and a seed crystal was attached to the lower end thereof. 7 kg of polycrystalline GaAs raw material in the crucible
Housed. The crucible containing the raw material was placed in the quartz tube 25 containing 50 g of solid As in the reservoir 63.
The quartz tube 25 was vacuum-sealed and placed at a predetermined position in the chamber 55. After the inside of the chamber 55 was evacuated, the raw materials were melted while adjusting the outputs of the heaters 1-10. While maintaining the temperature gradient at the growth interface at 2-3 ° C / cm, the temperature was gradually lowered to grow a single crystal having a length of about 250 mm. In the apparatus of the present invention, the accuracy of controlling the temperature distribution in the crystal and melt was significantly improved. The accuracy of the temperature gradient control at the growth interface, which is particularly important for lowering the dislocation density, was about ± 1 ° C. in the past, but is ± 0.1 in the apparatus of the present invention.
It was within ℃. As a result, crystals with a low dislocation density of 2 × 10 ³ cm ⁻² or less from the front to the back can be stably obtained. As a result of improved control of the growth interface, defects such as twins and lineage were significantly reduced.

2. Example of Application to LEC Method FIG. 2A shows a specific example of application of the present invention to the LEC method. In the LEC device 75, a susceptor 35 supported by a rotatable lower shaft 29 is provided in the high pressure chamber 27. A crucible 36 is provided in the susceptor 35. In addition, three adjacent heaters 30, 31, and 32 are arranged around the susceptor 35. Each heater is
It is partitioned by PBN-coated carbon shielding plates 33 and 34 attached to the heat insulating cylinder 60.
As shown in FIG. 2B, the shield plates 33 and 34 have a hollow disk shape. A raw material melt 37 is accommodated in the crucible 36, and a liquid sealant 38 is provided on the melt.
On the other hand, in the high pressure chamber 27, above the center of the crucible 36, an upper shaft 28 capable of rotating and elevating is provided. In the apparatus configured as described above, the growth of a single crystal is performed under a pressurized atmosphere of an inert gas such as nitrogen and argon, and the single crystal 40 to the single crystal 40 attached to the lower end of the upper shaft 28 are separated. Be lifted.

Using the device shown in FIG. 2 (a), LEC
According to the method, a 3 inch φ non-doped GaAs single crystal was grown. As the crucible 36, a PBN crucible having an 8 inch diameter was used. GaAs polycrystal raw material about 9kg and B
About 1 kg of ₂ O ₃ was put into the crucible 36. Heater 30
After the raw materials were melted by the heating of ~ 32, the heater output was adjusted so as to obtain the desired temperature gradient. Then,
Crucible rotation speed of 30 in an atmosphere of Ar gas of 20 atm
rpm, seed crystal rotation speed 2 rpm, pulling speed 10 mm
Growth was performed under the condition of / h. As a result, the diameter is about 82m
A single crystal having a length of m and a length of about 35 cm was obtained.

In the crystal grown by the conventional apparatus which does not use the shielding plate, the diameter variation is as large as ± 2 to 3 mm, and the dislocation density is 2 to 4 × 10 ⁴ c from the front to the back of the crystal.
It varied in the range of m ^-2 . On the other hand, with the apparatus of the present invention, stable temperature distribution control was possible, and as a result, the crystal diameter fluctuation could be controlled within ± 1 mm. Also, the dislocation density from the front to the back is 2 × 10 ⁴ cm.
It could be ^-2 or less. Furthermore, the occurrence of twins, lineage and freezeouts was significantly reduced.

3. Example of Application to Pulling Method under High Dissociation Pressure Component Gas Atmosphere FIG. 3 shows an example of applying the present invention to the Czochralski method under a high dissociation pressure component gas atmosphere. In the apparatus shown in the figure, a heat insulating cylinder 61 is provided in the high pressure chamber 27, and an airtight container 41 for pulling a single crystal therein is provided therein. The airtight container 41 is formed with a reservoir 56 for controlling the partial pressure in the container. A heater 57 is provided around the reservoir 56, and the airtight container 4 is provided.
Surrounding 1 is five heaters 46, 47, 4 from top to bottom.
8, 49 and 50 are provided. A hollow disk-shaped shield plate 59 made of PBN coated carbon is provided between the heaters 57 and 46, and a hollow disk-shaped shield plate 51, 52 made of PBN coated carbon is also provided between the heaters 46 to 50. , 53 and 54 are provided respectively.

Inside the airtight container 41, a susceptor 35 supported by a lower shaft 29 which can be rotated and moved up and down is provided. A crucible 36 is provided in the susceptor 35, and a raw material melt 37 and a liquid sealant 38 are contained in the crucible 36. Above the center of the crucible 36, an upper shaft 28 that can be rotated and raised and lowered is provided, and a seed crystal 39 is attached to the lower stage thereof. Sealing agent reservoirs 42 and 43 are provided at the portions where the upper shaft 28 and the lower shaft 29 penetrate the airtight container 41, and the airtightness is maintained by containing the liquid sealing agents 44 and 45, respectively. .. In the apparatus configured as described above, the airtight container 41 is filled with the vapor of the high dissociation pressure component element together with the inert gas such as N ₂ and Ar, and the raw material melt is set by the upper shaft 28 in the atmosphere. The single crystal 40 is pulled from.

Using the apparatus shown in FIG. 3, a 3 inch φ non-doped GaAs single crystal was grown. Airtight container 4
1 was made of carbon coated with PBN. As the crucible 36, a 6-inch φ PBN crucible was used.
About 6 kg of GaAs polycrystalline raw material and about 500 g of B ₂ O ₃
Was put into the crucible 36. On the other hand, solid As was put into the reservoir 56. The liquid sealants 44 and 45 in the sealant reservoirs 42 and 43 are heated by the heaters 46 and 50.
Were melted and the airtight container 41 was sealed, and then the airtight container 41 was filled with As gas. After the raw materials were melted by heating the heaters 47 to 49, the output of each heater was adjusted so as to obtain a desired temperature gradient. As gas partial pressure 1a
Growth was carried out in an atmosphere of tm and Ar gas partial pressure of 4 atm at a crucible rotation speed of 10 rpm, a crystal rotation speed of 2 rpm, and a pulling speed of 6 mm / h to obtain a single crystal having a diameter of about 82 mm and a length of about 27 cm.

[0019] The results obtained by the conventional device without using the shield plate
In the crystal, the fluctuation of the diameter is as large as ± 3 to 4 mm, and
The dislocation density is 2 to 5 × 10 from the front to the back.³
cm ^-2It varied in the range. On the other hand, according to the present invention
The device enables stable control of temperature distribution.
As a result, the diameter fluctuation of the crystal can be controlled within ± 1 mm,
Dislocation density from 1 to 2 × 10 from top to back³cm^-2Control
I was able to do it. In addition, twins, lineage and freezers
Outbreaks such as plumage were significantly reduced.

In the above embodiments, the VGF method and the pulling method are shown as concrete examples, but the same effect can be obtained in the HB method, the VB method and the HGF method by using the shielding member for partitioning the heater.

[0021]

As described above, according to the present invention, the control of crystal growth is further improved by increasing the accuracy of temperature control for each heater. According to the present invention, it is possible to suppress the generation of twin crystals, lineage, freeze-out and the like in crystal growth. In addition, the dislocation density can be suppressed low throughout the growing crystal. In particular, the present invention relates to the Czochralski method, LEC
Method, the HB method, the VB method, the HGF method, and the VGF method contribute to the improvement of crystal quality and productivity in the production of a single crystal.

[Brief description of drawings]

FIG. 1 is a schematic view showing a specific example in which the present invention is applied to a VGF method apparatus.

FIG. 2 is a schematic diagram showing a specific example in which the present invention is applied to an apparatus for LEC method.

FIG. 3 is a schematic diagram showing a specific example in which the present invention is applied to an apparatus for producing a single crystal by the Czochralski method in a high dissociation pressure component gas atmosphere.

FIG. 4 is a schematic view showing a specific example of a conventional single crystal manufacturing apparatus.

[Explanation of symbols]

 1-10, 30-32, 46-50, 57 Heater 11-19, 33, 34, 51-54, 59 Shielding plate

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H01L 21/208 P 7353-4M 21/368 Z 7353-4M

Claims (4)

[Claims] 1. A single crystal manufacturing apparatus having a plurality of heaters adjacent to each other, further comprising a shielding member for partitioning each heater. 2. The apparatus for producing a single crystal according to claim 1, wherein the shielding member is formed of at least one of carbon, quartz, pyrolytic boron nitride, boron nitride, SiC, Si ₃ N ₄ and AlN. .. 3. The single crystal manufacturing apparatus according to claim 1, wherein the single crystal is one of a III-V group compound semiconductor single crystal and a II-VI group compound semiconductor single crystal. 4. The single crystal is produced according to any one of the Czochralski method, the liquid capsule pulling method, the horizontal Bridgman method, the vertical Bridgman method, the horizontal temperature gradient solidification method, and the vertical temperature gradient solidification method. The single crystal manufacturing apparatus according to claim 1.