JPH08319197A - Production of indium antimony single crystal - Google Patents

Abstract

PURPOSE: To obtain an InSb single crystal having low transition at a shorter time than the time required hitherto in good yield by adding impurity to InSb crystal body used as a raw material and monotonously increasing crystal diameter at a definite shoulder-forming angle from starting of crystal growth to a growth phase of crystal having prescribed diameter. CONSTITUTION: This indium antimony single crystal is produced by a pulling up method. High-purity InSb crystal used as a raw material and an element of a III-V group compound which becomes impurity and is electrically neutral in crystal are charged into a quartz crucible 2 in a chamber 1 and a seed crystal 3 is attached to a seed crystal-attaching jig 4 and sealed with a chamber 1. The chamber 1 is evacuated and packed with a forming gas composed of 90% nitrogen and 10% hydrogen. The seed crystal is melted by heating the crystal to a temperature higher than the melting point (525 deg.C) of InSb to prepare InSb melt 6. Seeding of the single crystal is carried out at 550 deg.C melting temperature and the single crystal is rotated and pulled up to start growth of crystal. After seeding, formation of shoulder part 7 is immediately started at <=20 deg. shoulder forming angle and then, cylinder part 8 is formed to produce the objective InSb single crystal 9.

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 single crystal by the Czochralski method.

[0002]

2. Description of the Related Art In recent years, the influence of dislocations on device characteristics has become clear, and reducing dislocations has become an important issue. For example, it is known that when the dislocation density in the semiconductor single crystal becomes large, the reverse leakage current of the pn junction formed in the crystal increases, and the semiconductor device characteristics deteriorate and the reliability is adversely affected. ing. Recently, the demand for reduction of crystal defects such as dislocation of a semiconductor single crystal has become stronger with the higher integration of semiconductor elements.

Conventionally, as an effective method for reducing dislocation, there is a method for suppressing dislocation propagation from seed crystals.
The neck-down method used for pulling a single crystal of silicon (Si), gallium arsenide (GaAs) or the like is also an effective method for pulling an indium antimony (InSb) single crystal.

However, the pulling of InSb single crystal is performed by Si, G
Twinning is more likely to occur than pulling a single crystal such as aAs, so special consideration is required. Usually, for pulling InSb single crystal, a single crystal pulling apparatus shown in a sectional view in FIG. 2 is used. As shown in the figure, an InSb crystal is placed in a quartz crucible 2 arranged in a chamber 1 and, for example, 5 × 5 × 50
Pulling is performed using a Seed3 of a rectangular parallelepiped having a size of mm.
In the figure, 4 is a Seed mounting jig, and 5 is a heater surrounding the quartz crucible 2. Regarding the crystal orientation of Seed3, [111] is the most unlikely to cause twinning, and then [211], [311], and [100] in that order (RF HULME, JB MULIN; Sol.
id State Electronics 1962
Vol. 15 pp 211-247). Therefore, crystal orientations such as [111] and [211] in which twinning is relatively less likely to occur as compared with the [311] and [100] orientations are used. Then, as shown in FIG. 2, the neck portion 101 and the shoulder portion 10 are formed from the InSb melt 6 using the Seed 3 described above.
2. The single crystal body 104 is pulled up by sequentially forming the body portion 103.

The most important point in the above-mentioned single crystal pulling step is the step of forming the shoulder 102. This is because most twins are generated in this region even if seeds of [111] and [211] orientations are used. The following methods have been tried as effective means for suppressing the generation of twins. That is, in raising the [111] direction, the shoulder forming angle is set to 30 ° or less after the neck down. On the other hand, in the [211] pulling up, the shoulder forming angle is set to 20 ° or less after the neck down. It is empirically known that twins are considerably suppressed by setting the shoulder forming angles as described above.

However, the above method has the following problems. First of all, twinning is most unlikely to occur in the [111] orientation pulling up compared to other orientations. However, according to the result of the crystal defect evaluation, the single crystal pulled up in this orientation has dislocations concentrated from the center of the wafer to the intermediate region. To do. The dislocation density is on the order of 10 ³ cm ^-2 or more. The dislocations in a wafer cut out from such a single crystal usually show a Y-shaped pattern. Therefore, when a semiconductor device is produced using such a wafer, the pn formed in the crystal is
The reverse leakage current of the junction increases, the device characteristics deteriorate, and the reliability is adversely affected.
11] Seed of direction cannot be used. On the other hand, in pulling in other orientations, for example, pulling in the [211] orientation, dislocations are present only in the facet region in the peripheral portion of the wafer (dislocation density is on the order of 10 ² cm ^-2 ), but in the [111] orientation, The dislocation density is not seen from the center to the intermediate region, and the dislocation density is a little (on the order of dislocation density of 10 ¹ cm ⁻² ) on average, and the device can be applied.

Next, in the case of InSb pulling up, unlike Si, GaAs and the like, after neck down, the crystal diameter rapidly increases and the shoulder cannot be formed. The reason for this is that, as described above, it is empirically known that when the shoulder forming angle is 20 ° or more, twin crystals are always formed. As a result, in the case of InSb, the shoulder area is S
It is many times longer than i and GaAs, and it takes half the time required for the entire pulling process only by forming the neck and shoulder. In addition, the shoulder formation angle must be constantly kept at 20 ° or less after neck down to suppress twinning, and the reproducibility of single crystal production is extremely poor.

[0008]

As described above, it is possible to suppress the dislocation propagation from the seed by forming the shoulder region by setting the shoulder forming angle to 20 ° or less after the neck down, and It is also an effective means because it also suppresses twinning. However, it is not easy to hold the angle of shoulder formation to 20 ° or less and pull it up after necking down, and the single crystallization rate remarkably deteriorates. Further, in the case of InSb single crystal, the shoulder portion must be formed with a shoulder angle of 20 ° or less.
There is a problem that the time required for forming the shoulder portion is about half of the time required for the entire pulling process. The present invention eliminates the above-mentioned drawbacks, and provides a method for producing a low-dislocation InSb single crystal with a good yield in a shorter time than ever before.

[0009]

In order to achieve the above object, in the present invention, when an indium antimony single crystal is produced by a pulling method as an invention corresponding to claim 1,
An indium antimony single crystal manufacturing method is characterized in that impurities are added to an indium antimony crystal used as a raw material, and the crystal diameter is monotonically increased with a constant shoulder forming angle until a predetermined diameter is reached immediately after the start of crystal growth. The invention corresponding to claim 2 is the method for producing an indium antimony single crystal according to claim 1, wherein the impurities include an element that becomes an electrically neutral impurity in the crystal. As an invention corresponding to claim 3, the shoulder forming angle is 20 ° or less, and the method for producing an indium antimony single crystal according to claim 1 is provided. According to a fourth aspect of the invention, the shoulder forming angle is 20 ° or less, and the indium antimony single crystal manufacturing method according to the first aspect is provided. The invention corresponding to claim 5 is the method for producing an indium antimony single crystal according to claim 1, wherein the impurity is gallium. The invention corresponding to claim 6 is the method for producing an indium antimony single crystal according to claim 1, wherein the impurity is gallium nitride. The invention corresponding to claim 7 is characterized in that the impurity is made of gallium and the shoulder formation angle is 20 ° or less.
The method for producing the indium antimony single crystal described above is used.
The invention corresponding to claim 8 is that the impurity is gallium nitride, and the shoulder formation angle is 20 ° or less, and the method for manufacturing an indium antimony single crystal according to claim 1.

[0010]

In order to suppress the dislocation propagation from Seed, it was essential to adopt the neck-down process. However, in the manufacturing method of the present invention, impurities are added to reduce dislocations. Therefore, the neck portion forming step can be omitted. As a result, it is only necessary to monotonically increase the diameter from immediately below Seed (immediately after the start of crystal growth) to a predetermined diameter at a shoulder angle of 20 °, and it is not necessary to raise or lower the InSb melt temperature (to lower the melt temperature. The temperature is raised to the lower limit and the temperature is lowered to form shoulders.) It is easier to control the shoulder formation angle, twinning is suppressed, and the time required to complete the conventional shoulder formation is reduced to about 1/2. Shortened. It was also found that this impurity addition method has the effect of reducing dislocation propagation from Seed even in the early stage of shoulder formation.

[0011]

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 I used for pulling InSb single crystal
For example, 700 g of nSb crystal and high-purity gallium (Ga)
60 mg is put into a quartz crucible 2 arranged in the chamber 1, and Seed 3 cut out in a [211] direction as a seed crystal (Seed) is attached to a seed crystal attachment jig 4 and sealed in the chamber 1. Next, the inside of the sealed chamber 1 is evacuated to a vacuum degree of 10 ⁻⁴ Torr, and nitrogen 9
Fill with a forming gas consisting of 0% and 10% hydrogen.
Then, this forming gas is allowed to flow in the chamber 1. Then, the heater 5 surrounding the crucible 2 is used to
The InSb crystal is melted by heating the InSb crystal to a temperature higher than the melting point of Sb of 525 ° C., for example, 600 ° C. Then, as shown in FIG. 1, for example, a pulling speed of 10 m
Seed at m / h, seed rotation speed 10 rpm, and melt temperature 550 ° C. to start crystal growth.

In the present invention, since the impurity Ga is added in order to suppress the dislocation propagation from Seed, the neck-down step can be omitted. Therefore, the neck formation itself is not performed, and the shoulder formation 7 can be immediately entered at a shoulder formation angle of 20 ° or less after seeding. Then, the body portion 8 is formed and I
nSb single crystal 9 is manufactured.

In the conventional method, since the neck down is performed as described above, the melt temperature is gradually increased at a rate of, for example, 0.1 ° C./min, and the minimum diameter of the neck portion is 1.5 mmφ which is thinner than the seed 5 × 5 mm square. Narrow down to After that, the melt temperature is gradually lowered to form shoulders. It is not easy to control the melt temperature during this period, and unlike the case where the melt temperature is lowered monotonously as in the present invention, twinning is significantly increased. Further, since the neck portion is formed, the time required for this is twice as long as in the case of forming the shoulder portion only as in the present invention.

In the present invention, the impurity Ga is added in order to control the dislocation propagation from Seed. As described above, in order to check whether or not the addition of the impurity Ga has the effect of suppressing dislocation, the crystal defect evaluation of the InSb single crystal pulled by the present invention was performed by the following procedure. In this evaluation, the In grown by the etching method was first grown in the [211] direction.
A (111) plane wafer was cut out from an Sb single crystal ingot, and the (111) In plane was cut with Al ₂ O having a grain size of 16 μm.
_Three powders to 0.05 μm were sequentially polished to a mirror finish. Next, in order to remove polishing scratches, etching was performed at 20 ° C. for 5 minutes using an etching solution having a composition ratio of CH ₃ CH (OH) COOH: HNO ₃ = 6: 1. After that, the composition ratio is 49% to detect etch pits.
Etching was performed at 20 ° C. for 1 minute using an etching solution of HF: 35% H ₂ O ₂ : H ₂ O = 1: 2: 2.

As a result, D-pits corresponding to dislocations
(Dislocation-pits) is slightly (dislocation density 10 ¹ cm ^-2 ) in the facet region in the peripheral portion of the wafer.
However, it was found that the method of the present invention is an extremely effective method for pulling InSb single crystal.

In the above-mentioned embodiments, the addition of the impurity Ga has been described, but needless to say, it is not limited to Ga alone, and G which is electrically neutral to InSb such as gallium nitride (GaN) is used.
Any a and V group compound (which does not affect the carrier concentration) can be applied.

[0017]

As described above, according to the present invention, s
Since the impurity addition method is used to suppress the dislocation propagation from seeds, the neck portion forming step in which twinning occurs frequently can be omitted. Therefore, since the shoulder portion and the body portion are pulled up, the single crystallization rate is significantly improved from 20% to 80%, and the time required for pulling up the neck portion can be omitted. It is shortened to 1/2. Further, the present invention is more effective in reducing dislocations than the neck-down method. As a result, a low-dislocation InSb single crystal can be manufactured with a high yield in a shorter time than ever before, and the economic effect is remarkably increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a single crystal pulling apparatus used in an example of the present invention.

FIG. 2 is a sectional view illustrating a single crystal pulling apparatus used in a conventional method.

[Explanation of symbols]

 1. Chamber 2. Quartz crucible 3. Seed crystal (Seed) 4. Seed crystal mounting jig 5. Heater 6. InSb melt 9,104. InSb single crystal

Claims (8)

[Claims] 1. When an indium antimony single crystal is manufactured by a pulling method, impurities are added to an indium antimony crystal used as a raw material, and the crystal diameter is monotonically changed with a constant shoulder forming angle immediately after the start of crystal growth until a predetermined diameter is reached. A method for producing an indium antimony single crystal, which is characterized by increasing the amount. 2. The method for producing an indium antimony single crystal according to claim 1, wherein the impurities include an element which becomes an electrically neutral impurity in the crystal. 3. The method for producing an indium antimony single crystal according to claim 1, wherein the impurity is a III-V group compound which becomes an electrically neutral impurity in the crystal. 4. The method for producing an indium antimony single crystal according to claim 1, wherein the shoulder forming angle is 20 ° or less. 5. The method for producing an indium antimony single crystal according to claim 1, wherein the impurity is gallium. 6. The method for producing an indium antimony single crystal according to claim 1, wherein the impurity is gallium nitride. 7. The method for producing an indium antimony single crystal according to claim 1, wherein the impurity is gallium and the shoulder formation angle is 20 ° or less. 8. The method for producing an indium antimony single crystal according to claim 1, wherein the impurity is gallium nitride, and the shoulder forming angle is 20 ° or less.