JPH09255497A - Method for producing indium antimony single crystal - Google Patents

Abstract

(57) Abstract: To provide a method for producing an indium antimony single crystal with few dislocations with a high yield. As a pull-up atmosphere gas, a gas containing helium as a main component and containing 10 to 20% by volume of hydrogen is used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an indium antimony single crystal.

[0002]

2. Description of the Related Art In recent years, the influence of dislocations in crystals 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 a semiconductor single crystal becomes large, the characteristics of the semiconductor device are deteriorated such that the reverse leakage current of the pn junction formed in the crystal is increased and the reliability is adversely affected. There is. Recently, as semiconductor devices have been highly integrated, demands for reducing crystal defects such as dislocations in semiconductor single crystals have been increasing.

Conventionally, as an effective method of reducing dislocations, there is a method of adding an element which becomes an electrically neutral impurity in a crystal. In this method, impurities to be added and raw materials to be pulled are put in a crucible, and then heated and melted to form a melt, and a single crystal is pulled. In an indium antimony (InSb) crystal, it is effective to use a gas containing nitrogen (N ₂ ) as a main component as a pulling atmosphere gas and add nitrogen of a group V element as indium nitride (InN, powder) as an impurity. JP-A-54-1
It is reported in Japanese Patent No. 22681.

However, this method has the following problems. First, InN is added by S-pits (Saucer-lik
It shows a remarkable reduction effect for minute defects corresponding to e-pits), P-pits (Punching-out-pits), and the like. However, no reduction effect is observed for dislocations.

Here, the S-pits have a shape of Sauc.
er) is a pit that is similar to that of a micro defect.
P-pits means that there are precipitations or defects of impurities in the central portion, and S-pits in the [110] direction around the presence of impurities.
s has occurred.

Next, the impurity element is added as an InN compound as described above because of a slight addition. Then, a fine powder is used to facilitate melting in the melt and improve weighing accuracy (for example, in the case of InN, the particle size of the powder is about 10 μm).
m). The fine powder is stored in an ampoule filled with an inert gas, but since the surface area is larger than that of the bulk, a natural oxide film is likely to be formed simultaneously with opening the ampoule. Therefore, after the compound is decomposed in the melt, oxide scum (floating residue) is formed on the melt surface.

It is well known that scum on the melt surface has various adverse effects on pulling of a single crystal. For example, it impedes seeding and crystal growth, and is one of the causes of twinning and polycrystallization. Therefore, it is an important issue to remove the scum which hinders pulling.

[0008]

As described above, the method of adding an electrically neutral impurity in a crystal is effective in reducing fine defects, but is not effective in reducing dislocations. In addition, this method often forms a scum on the surface of the melt, which is an obstacle to pulling the single crystal, making it difficult to pull the single crystal, that is, the rate at which the single crystal can be pulled, that is, the single crystallization rate is extremely poor. There was a problem that

It is an object of the present invention to provide a method for producing an indium antimony single crystal which produces a low dislocation single crystal with good yield without generating scum.

[0010]

In order to achieve the above object, the present invention provides a method of producing an indium antimony single crystal by pulling an indium antimony single crystal, wherein a gas containing helium as a main component is used as a pulling atmosphere gas. A method for producing an indium antimony single crystal, which is characterized in that it is used.

Further, the gas containing helium as a main component is composed of a mixed gas of helium and hydrogen.

The mixed gas of helium and hydrogen is characterized by containing 10% to 20% by volume of hydrogen.

Further, the indium antimony single crystal is <2
11> It is characterized by pulling up in the direction.

Further, it is characterized in that the indium antimony single crystal is pulled undoped.

Generally, as a method of reducing dislocations, in order to suppress the generation of dislocations due to thermal strain, the temperature gradient in the pulling axis direction is reduced to optimize the thermal environment, and the pinning effect by the addition of impurities is utilized. Then, the two-stage method is adopted in which the propagation of dislocation is blocked. Here, the use of the pinning effect is a method of preventing the propagation of dislocations by the binding force between impurities and In atoms and between impurities and Sb atoms.

However, in the present invention, the pulling atmosphere gas containing nitrogen as a main component (hydrogen in a volume ratio of 10 to 10%) is added to the melt surface without adding impurities that generate scum which hinders pulling of the single crystal. Low dislocation is achieved by changing from a gas containing 20%) to a gas containing helium as a main component (containing 10 to 20% by volume of hydrogen). The reason for this is that the gas containing helium (He) as a main component has a temperature gradient in the pulling axial direction reduced to 2/3 as compared with the gas containing nitrogen as a main component. The volume ratio of hydrogen (H ₂ ) is 10 to 2
The content of 0% is to prevent the oxidation of the surface of the single crystal.

[0017]

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 the pulling device used in this embodiment. A high-purity InSb polycrystal used for pulling an InSb single crystal, for example, 700 g, was placed in a quartz crucible 2 in a chamber 1, a seed crystal 3 cut out in a <211> orientation was attached to a seed crystal attachment jig 4, and the chamber 1
Seal with. Solid impurities for impurity addition are not added.

Next, the pressure in the sealed chamber 1 is reduced to 10 ^-4.
Evacuated to Torr and mixed gas (volume ratio 90% He
+ 10% H ₂ ) and the mixed gas is allowed to flow at a constant flow rate. Then, the heater 5 surrounding the crucible 2
The InSb polycrystal is made by melting the InSb polycrystal by heating 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
mm / h, seed rotation number 10 rpm, melt temperature 550 ° C.
InSb single crystal 7 is manufactured by seeding with. In this case, since there is no impurity doping from the gas, the pulling is undoped.

In order to check whether the gas containing He as the main component of the present invention is effective in reducing dislocations, the crystal defects of InSb single crystals pulled by the method of the present invention were evaluated by the following procedure.

This evaluation uses the etching method.
A (111) plane wafer was cut out from an InSb single crystal ingot grown in the 211> direction, and the (111) I
0.05 μm on the n-face from Al ₂ O ₃ powder with a particle size of 16 μm
It was sequentially polished until it became a mirror surface.

Next, the composition ratio is CH ₃ C to remove polishing scratches.
Etching was performed at 20 ° C. for 5 minutes using an etching solution of H (OH) COOH: HNO ₃ = 6: 1. After that, the composition ratio is 49% HF: 3 to detect etch pits.
Etching was performed at 20 ° C. for 1 minute using an etching solution of 5% H ₂ O ₂ : H ₂ O = 1: 2: 2.

As a result, D-pits corresponding to dislocations
(Dislocation-pits) is slightly facet region at the wafer peripheral portion (dislocation density 10 ⁰ cm ^-2 order) are present. However, from the center of the wafer to the intermediate area, Dp
Its was not observed at all, and the conventional method (addition of impurity InN,
The dislocation density of the InSb single crystal pulled up by pulling in a gas atmosphere containing N ₂ as a main component) is remarkably reduced as compared with the dislocation density of the order of 10 ³ cm ⁻² .

As a result, it was found that the gas containing He as a main component was a pulling atmosphere gas effective for low dislocation. Here, a facet is a surface of a small area having a specific plane orientation that is found around a single crystal ingot.

In the above embodiment, the case where the pulling atmosphere gas contains 10% hydrogen by volume (hereinafter, the mixing ratio of gas is by volume) has been described. However, hydrogen 10-20
%, A low dislocation single crystal equivalent to 10% hydrogen can be obtained. However, when the hydrogen content exceeds 20%, it becomes difficult to control the crystal size. On the other hand, when the hydrogen content is less than 10%, the surface of the single crystal is oxidized.

From the above results, in the present invention, it is not necessary to limit the atmosphere gas for pulling up to contain 10% hydrogen.
Up to 20% of hydrogen can be applied as a gas containing as a main component. As described above, according to the present invention, even if an impurity element is not added to reduce dislocations, a low dislocation density can be easily achieved by using a gas containing He as a main component, and the dislocation density can be reduced by the conventional method. From 10 ³ cm ^-2 to 10 ⁰ cm ^-2 .

Further, since the scum of the oxide due to the impurity element does not exist on the melt surface, seeding and crystal growth are facilitated, and as a result, twinning and polycrystal formation are suppressed, and the single crystallization rate is conventionally. From 20% to 80%.

[0028]

According to the present invention, scum is not generated,
A method for producing an indium antimony single crystal capable of producing a low dislocation single crystal with high yield can be realized.

[Brief description of drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Chamber 2 ... Quartz crucible 3 ... Seed crystal 4 ... Seed crystal attachment jig 5 ... Heater 6 ... InSb melt 7 ... InSb single crystal

Claims (5)

[Claims] 1. A method for producing an indium antimony single crystal, wherein a gas containing helium as a main component is used as a pulling atmosphere gas in the method for producing an indium antimony single crystal by a pulling method. 2. The method for producing an indium antimony single crystal according to claim 1, wherein the gas containing helium as a main component comprises a mixed gas of helium and hydrogen. 3. The method for producing an indium antimony single crystal according to claim 1, wherein the mixed gas of helium and hydrogen contains 10% to 20% by volume of hydrogen. 4. The indium antimony single crystal is <2.
The method for producing an indium antimony single crystal according to claim 1, wherein the pulling is performed in the 11> direction. 5. The method for producing an indium antimony single crystal according to claim 1, wherein the indium antimony single crystal is pulled undoped.