JPH061700A - Production of indium antimonide single crystal - Google Patents

Abstract

PURPOSE:To obtain an InSb single crystal in a short time in good yield by using a single crystal body section having a non-vertical peripheral surface at the intial pulling stage as a seed crystal. CONSTITUTION:The single crystal body section 11 having a non-vertical peripheral surface of an InSb single-crystal pulled up in the [211] orientation is used as a seed crystal. A high-purity InSb polycrystal is placed in a crucible 2 arranged in a chamber 1, and the seed crystal is fixed to a single crystal adapter 4 and sealed by the chamber 1. The chamber 1 is evacuated to <=10<-4>Torr and filled with a forming gas. The crucible 2 is then heated by a heater 5 to melt the InSb polycrystal, and molten InSb 6 is obtained. The seed crystal is rotated, lowered 3-5mm above the molten material, kept for about 20 min, dipped in the molten material 6 and pulled up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pulling up an indium antimony (InSb) single crystal by the Czochralski method.

[0002]

2. Description of the Related Art In pulling a single crystal, it is an important subject to suppress the generation of twin crystals and increase the rate of single crystallization. Indium antimony (InSb)
Single crystal pulling is performed on silicon (Si) and gallium arsenide (Ga).
Twinning is more likely to occur than pulling a single crystal such as As) or indium phosphide (InP), so special consideration is required.

Usually, for pulling an InSb single crystal, a single crystal pulling apparatus shown in a sectional view in FIG. 3 is used. As shown in the figure, InSb is placed in the quartz crucible 2 arranged in the chamber 1.
The polycrystalline body 3 is placed and pulled up using a 5 × 5 × 50 mm rectangular parallelepiped seed crystal (Seed, hereinafter abbreviated as a seed) 101. In the drawing, 4 is a seed attachment jig, and 5 is a heater that surrounds the quartz crucible 2 laterally. The orientation of the seed is [111], [211], [311],
Twins are likely to occur in the order of [100] (RF HUL
ME, J. B. MULIN; Solid State
Electronics 1962 Vol 15
pp211-247), [311], [10
Twins are less likely to occur as compared to the [0] orientation [11
1], [211], etc. are used. Then, as shown in FIG. 4, a neck portion 102, a shoulder portion 103, and a body portion 104 are sequentially formed using the seed 101 to form a single crystal body 105.
Pull up. The most important step in the single crystal pulling step is the shoulder forming step. The reason for this is
This is because most twins are generated in this region even if seeds of [1] and [211] orientations are used. The following methods have been tried as effective means for suppressing the generation of twins. That is, when raising the [111] direction, the shoulder angle is 20 ° C.
Set as follows. On the other hand, in [211] pulling up, the shoulder angle is 1
Set it to 5 ° or less. It is empirically known that twins are considerably suppressed by setting the shoulder angles as described above.

However, the above method has the following problems. First of all, twinning is less likely to occur in the [111] orientation pulling than in other orientations, but as a result of the crystal defect evaluation, the single crystal pulled up in this orientation has dense dislocations from the center of the wafer to the intermediate region. . The dislocation density is 10 ³ c
The order is m ^-2 . The dislocations in a wafer cut out from such a single crystal usually show a Y-shaped pattern. Therefore, when a semiconductor device is manufactured using such a wafer, the reverse leakage current of the pn junction formed in the crystal increases, the device characteristics deteriorate, and the reliability is adversely affected. No seeds can be used. On the other hand, in pulling in other orientations, for example, in pulling in the [211] orientation, some dislocations exist only in the facet region in the peripheral portion of the wafer (the dislocation density is 10 ° cm.
The order of ^-2 ) is applicable to the device, since dislocation density is not seen from the center of the wafer to the intermediate region like the [111] orientation. The next problem is that in the case of InSb pulling up, unlike Si, GaAs, etc., the crystal diameter suddenly increases from the neck and the body cannot be formed. It has been empirically known that twins will be formed, and it is called shoulder formation (this shoulder region has a small crystal size and is not constant, so this part of the wafer is practical for device fabrication). (Non-target) process, and the time required for this process reaches about 1/2 of the total process, resulting in a significant time loss. Moreover, the shoulder angle is constantly set to 1 in order to suppress twinning.
There is a problem that it is controlled to 5 ° or less, and the reproducibility is poor.

[0005]

As described above, forming the shoulder region by setting the shoulder angle to 15 ° or less is certainly effective in suppressing twinning, but the shoulder angle is It is not easy to pull up while constantly maintaining the angle below 15 °, and the single crystallization rate is significantly deteriorated. Further, in the case of an InSb single crystal, the shoulder region must be formed without fail, so that there is a problem that the time required for forming the shoulder region is increased and becomes about half of the time required for all steps.

The present invention eliminates the above-mentioned drawbacks, and provides a method for producing an InSb single crystal in a short time with a good yield.

[0007]

A method for producing an indium antimony single crystal according to the present invention comprises the steps of producing an indium antimony single crystal by a single crystal pulling method, in which a peripheral side surface of a pulling initial stage is a non-vertical single crystal body portion. It is characterized by being used as a seed crystal.

[0008]

According to the manufacturing method of the present invention, since a single crystal body portion having a non-vertical peripheral side surface at the initial stage of pulling, a so-called neck portion and a shoulder single crystal body portion is used as seed, a so-called body portion having a vertical peripheral side surface is used. Only the crystal may be pulled up, and it is not necessary to form the shoulder region where twinning is likely to occur. Also, the pulling time is reduced to about half that of the conventional one.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a pulling device used in this embodiment. High-purity InS used for pulling InSb single crystal
b For example, 700 g of polycrystal was put in a quartz crucible 2 arranged in a chamber 1, and as a seed crystal (seed), a region 11 corresponding to a shoulder portion of another InSb single crystal body pulled in a [211] orientation was set. It is cut out in advance (the maximum diameter of the shoulder is approximately equal to the single crystal diameter to be pulled, for example, 40 mmφ), and this is attached to the seed crystal attachment jig 4,
Seal with chamber 1. Next, the sealed chamber 1 is evacuated to a vacuum degree of 10 ⁻⁴ Torr or less and filled with a forming gas consisting of 90% nitrogen and 10% hydrogen. Subsequently, the heater 5 surrounding the crucible 2 is heated to 600 ° C.
The Sb polycrystal is melted to form an InSb melt 6. Continued S
It is brought close to 3 to 5 mm above the melt surface at an eded rotation speed of 10 rpm, and is held for, for example, about 20 minutes. The reason for this is seed 1
This is because the thermal strain that causes dislocation generation due to thermal shock at the moment when No. 1 contacts the melt is relaxed as much as possible. After that, as shown in FIG. 2, the body portion is pulled up by a conventional method at a pulling rate of 10 mm / h, a seed rotation number of 10 rpm, and a melt temperature of 550 ° C. to manufacture an InSb single crystal 7.
By the way, in the case of pulling by the method of the present invention, only the body portion needs to be pulled up.
The time required for pulling a single crystal is significantly improved from the conventional 22 hours to 1% while improving significantly from 0% to 80%.
It can be shortened to 2 hours, which is almost half the required time. The single crystallization rate is the yield that can be raised without twinning.

Conventionally, since the seed bottom portion alleviates generation of dislocation due to thermal shock at the moment of contact with the melt, it is 5 mm.
In the case of the present invention, the diameter of the seed is as large as about 40 mmφ as compared with the case of reducing the size to × 5 mm. Therefore, dislocations are generated in the seeds at the moment of contact with the melt, and the dislocations may propagate to the growth region (body). In order to check this, the crystal defect evaluation of the InSb single crystal pulled according to the present invention was performed in the following procedure. In this evaluation, a (111) plane wafer was cut out from an InSb single crystal ingot grown in the [211] direction by an etching method.
The (111) In surface was polished in order from Al ₂ O ₃ powder having a particle size of 16 μm to 0.05 μm to give a mirror surface. Next, in order to remove polishing scratches, the composition ratio is CH ₃ CH
Etching was performed at 20 ° C. for 5 minutes using an etching solution of (OH) COOH: HNO ₃ = 6: 1. After that, the composition ratio is 49% HF: 35 to detect the etch pit.
Etching was performed at 20 ° C. for 1 minute using an etching solution of% H ₂ O ₂ : H ₂ O = 1: 2: 2.

As a result, D-pits corresponding to dislocations
Only (dislocation-pits) is a normal S
As in the case of using eded, a small amount (dislocation density is of the order of one digit) exists in the facet region around the wafer,
S-pits (Source) corresponding to other micro defects
r-like-pits) and the central portion has precipitation or defects of impurities.
0] direction, S-pits are generated in the P-pits (Pu
Various pits such as nching-out-pits) were not observed, and it was found that a low crystal defect InSb single crystal was obtained.

From the above results, even when the seed 11 having a large crystal diameter is used as in the present invention, the conventional bottom portion is 5 mm.
It was found that a single crystal with a low crystal defect equivalent to the case of using a seed 101 of × 5 mm was obtained, and the present invention is an extremely effective method for pulling InSb single crystal.

[0013]

As described above, according to the present invention, a single crystal that has already been formed from the neck portion to the shoulder portion is used as a seed, so that the shoulder forming step in which twinning occurs frequently can be omitted. Therefore, since only the body part is pulled up, the single crystallization rate is greatly improved from 20% in the conventional method to 80%, and the time required for pulling is halved from 22 hours in the conventional method to 12 hours. Is significantly increased.

In the present invention, a single crystal formed from the neck portion to the shoulder portion is used as a seed. However, conventionally, the crystal diameter of this portion was not constant, so that it could not be used for a device. The present invention intends to use this unused shoulder region as a seed, and it is not necessary to newly create only this portion.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a single crystal pulling apparatus used in an example of a method of the present invention.

FIG. 2 is a cross-sectional view for continuing to explain “FIG. 1” of a single crystal pulling apparatus used in an example of the method of the present invention.

FIG. 3 is a sectional view for explaining a single crystal pulling apparatus used in a conventional method.

FIG. 4 is a cross-sectional view for continuing to explain “FIG. 3” of a single crystal pulling apparatus used in a conventional method.

[Explanation of symbols]

 1 Chamber 2 Quartz Crucible 3 Melt 4 Seed Crystal Attachment Jig 5 Heater 12 InSb Single Crystal 101 Seed Crystal (Seed)

Claims (1)

[Claims] 1. A method for producing an indium antimony single crystal, which comprises using, as a seed crystal, a single crystal body portion whose peripheral side surface in the initial stage of pulling is non-vertical when the indium antimony single crystal is produced by the single crystal pulling method.