JPH06144998A - Production of indium antimonide single crystal - Google Patents

Abstract

PURPOSE:To reduce all of crystal defects including dislocation and to obtain a single crystal in a high yield by synthesizing an InSb polycrystal in an atmosphere of a specified doping gas, adding elemental Ga or a Ga compd. to a melt of the polycrystal and carrying out single crystallization. CONSTITUTION:An InSb polycrystal is synthesized in an atmosphere of a gas of an element which becomes an electrically neutral impurity in a crystal, e.g. gaseous N2, Ga or a compd. of Ga with a group V element, e.g. GaSb is added to a melt of the InSb polycrystal and single crystallization is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an indium antimony single crystal, and more particularly to a method for pulling an indium antimony single crystal by the Czochralski method.

[0002]

2. Description of the Related Art In recent years, the influence of crystal defects on device characteristics has become clear, and reducing crystal defects has become an important issue. For example, it is known that when the dislocation density in a semiconductor single crystal becomes large, the reverse leakage current of the P / N junction formed in the crystal increases and the semiconductor device characteristics are deteriorated and the reliability is adversely affected. There is. Recently, the demand for reduction of dislocations and microscopic defects in semiconductor single crystals has become stronger with higher integration of semiconductor devices.

Conventionally, there has been a method of adding an electrically neutral impurity as an effective method of reducing crystal defects. This method is a method in which 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 the InSb crystal, it is effective to add nitrogen of the group V element as indium nitride (InN, powder) as an impurity.
22681.

However, InN has the following problems. Certainly, the addition of InN corresponds to the S-pi that corresponds to the minute defects.
ts (Saucer-like-pits) and precipitation or defects of impurities, which are mainly [110]
P-pits (Punc) in which S-pits are generated in the direction
Hing-out-pits) is significantly reduced, but D-pits (Dislo) corresponding to dislocations are shown.
Unfortunately, no reduction effect is observed for the (cation-pits). Therefore, in order to improve the characteristics and reliability of the semiconductor device, it is an important problem to find a method for simultaneously reducing not only the above S-pits and P-pits but also D-pits.

[0005]

As described above, the electrically neutral InN (powdered) addition method is dislocation (D-
Other than the pits), it is an effective method for reducing crystal defects, but it has a problem that it is completely useless for reducing dislocations.

The object of the present invention is to eliminate the above-mentioned defects, and to provide a method for reducing all crystal defects including dislocations and producing a single crystal with a high yield.

[0007]

In order to achieve the above object, a double doping method is adopted in the method for producing an InSb single crystal of the present invention. That is, nitrogen (N), which is a conventionally effective method for reducing crystal defects (S-pits, P-pits) other than dislocations (D-pits), is added. However,
As a nitrogen addition method, not as InN (powder),
N ₂ doping by gas is performed by using N ₂ gas as an atmospheric gas during the synthesis of InSb polycrystal. On the other hand, in order to reduce dislocations, a group V element such as gallium (Ga) alone or gallium antimony (GaSb) is added as a gallium compound into the InSb melt to pull up the InSb single crystal.

In summary, the method for producing an indium antimony single crystal according to the present invention comprises a step of synthesizing an indium antimony polycrystalline body in an atmosphere of a gas composed of an element which becomes an electrically neutral impurity in the crystal, The method is characterized by including a step of adding gallium or a compound of gallium and a group V element to the indium antimony polycrystal melt to obtain a single crystal.

[0009]

Function: N and Ga (including GaS) are included to reduce crystal defects.
The reason for adopting the double doping method of b) is that dislocations are not reduced by adding only N as described above.
On the other hand, when only Ga is added, dislocations are significantly reduced, but other pits (S-pits, P-pits) are not reduced.

From the above results, it is possible to reduce these pits by performing double doping, and by this double doping method, a single crystal having extremely few crystal defects can be obtained.

In the above manufacturing method, N doping by gas is adopted as a method of adding nitrogen instead of InN powder. There are two reasons for this.

One of them is that when the double doping of Ga and InN (powder) is attempted, the above-mentioned added impurities are deposited on the surface of the pulled single crystal. And because it does not form a solid solution,
No crystal defect reducing effect is recognized. However, the gas doping method avoids this point.

The use of the other powdery InN has the advantages of facilitating the melting in the melt and increasing the accuracy of weighing, but since it has a larger surface area than the bulk, it has a natural oxide film. Are easily formed. Therefore, after InN is decomposed in the melt, oxide scum is formed on the surface of the melt, which has various adverse effects on pulling of the single crystal. For example, it impedes seeding and crystal growth, and is one of the causes of twinning. On the other hand, in the gas doping method, the natural oxide film is not formed on the dopant. As a result, there is an advantage that scum of the oxide is not generated on the melt surface, the single crystal can be pulled up without being affected by the scum, and the single crystallization rate is remarkably improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1A shows a cross-sectional view of a polycrystalline synthesis furnace (normal freezing furnace) used in this example. 200 g of high-purity In raw material used for polycrystal synthesis and S
b Raw material 220 g (purity is 99.9999% each) is put in the quartz boat 1 and set in the reaction tube 2. Next, the inside of the reaction tube 2 is evacuated to a vacuum degree of 10 ⁻⁷ Torr. Then, the heater 3 surrounding the reaction tube 2 is heated to 750 ° C. to melt the In and Sb raw materials to form an InSb melt 4. After the formation, this state (in vacuum, 750 ° C.) is maintained for 1 hour. The reason for this is that in high temperature vacuum, Zn (zinc), Cd
This is because the P-type impurities such as (cadmium) are evaporated and removed from the melt 4. After that, the reaction tube 2 was filled with high-purity N ₂ (nitrogen) gas having a purity of 99.9999%, and the heater 3
Is moved at a speed of 12 mm / h to form an InSb polycrystal by a normal freezing method (a method of slowly solidifying from one end of the melt). Incidentally, the time required for polycrystal synthesis is about 24 hours, and the flow rate of N ₂ gas flown during this time is 0.5 l / min. In this step, InSb polycrystal is doped with N.

FIG. 1 (b) is a sectional view of the pulling device used in this embodiment. The high-purity InSb polycrystal used for pulling the InSb single crystal is, for example, 700 g and high-purity Ga.
60 mg (purity 99.99999%) is put into a quartz crucible 6 in the chamber 5, and the seed crystal 7 cut out in the <211> direction is attached to the seed crystal attachment jig 8 and sealed in the chamber 5. Next, the inside of the sealed chamber 5 is evacuated to a vacuum degree of 10 ⁻⁴ Torr, and 90% of nitrogen and 10% of hydrogen are discharged.
% Forming gas. Subsequently, the heater 9 surrounding the crucible 6 is heated to 600 ° C.
The InSb melt 10 is prepared by melting the polycrystal. The melt 1
Since the doping with the N ₂ gas of the present invention is attempted on the 0 plane, oxide scum does not exist unlike the case where powdery InN is used. Thereafter, as shown in FIG. 1B, for example, a pulling speed of 10 mm / h and a rotation speed of 10 rp
m, and a melt temperature of 555 ° C. is applied to produce an InSb single crystal body 11.

Next, in the present invention, N ₂ doping with gas is carried out as a method of adding nitrogen, but the crystal defects (S-pi) are also formed by such a gas doping method.
ts, P-pits) reduction effect and whether Ga addition is effective in reducing dislocations (D-pits).
The crystal defect evaluation of the single crystal was performed by the following procedure. In this evaluation, an etching method is used. First, a (111) plane wafer is cut out from an InSb single crystal ingot grown in the <211> direction, and the (111) In plane is cut from an Al ₂ O ₃ powder having a particle diameter of 16 μm to 0.2. It was polished to a mirror surface by sequentially polishing to a thickness of 05 μm. 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.
Then, in order to detect further etch pits, etching was performed at 20 ° C. for 1 minute using an etching solution having a composition ratio of 49% HF: 35% H ₂ O ₂ : H ₂ O = 1: 2: 2.

As a result, the S-p corresponding to the minute defect is firstly detected.
Its and the central portion have precipitation or defects of impurities, and the S-pit in the [110] direction around this is the center.
S-generated P-pits were not observed, and gas-induced N-
It turns out that the doping is effective. Next, D-pits corresponding to dislocations was remarkably reduced from the conventional dislocation density of the order of 10 ³ cm ^{-2 to the} order of 10 ⁰ cm ^-2, and it was found that Ga doping is an effective dopant for low dislocations.

From the above results, it was found that the double doping method of the present invention has an effect of reducing or reducing all pits including dislocations, and that the present invention is an extremely effective method for pulling InSb single crystal.

In the above embodiments, the case where Ga simple substance is added as a means for reducing dislocations has been described. However, it is not necessary to limit to Ga simple substance, and for example, when a group V element compound with Ga such as GaSb is added. It is also effective.

[0020]

As described above, by using the double doping method of N and Ga of the present invention, all crystal defects including dislocations can be reduced for the first time (dislocation density is 10 ³ cm of the conventional method). ^-2 depleted from the order and 10 ⁰ cm ^-2 order, S-pits other than dislocation, P-pits are absent). Moreover, as a result of adopting the N doping method by gas, double doping of N and Ga is possible for the first time, and since the scum of the oxide derived from InN (powder) does not exist on the melt surface, seeding and crystallization are performed. The growth was facilitated, and as a result, twinning was suppressed and the single crystallization rate (yield of pulling up without twinning) was significantly improved from the conventional 20% to 80%.

As described above, according to the present invention, it becomes possible to produce a single crystal having a low crystal defect with a high yield, and the economic effect is remarkably increased.

[Brief description of drawings]

FIG. 1A is a sectional view for explaining a polycrystal synthesis furnace (normal freezing furnace) used in an embodiment of the present invention, and FIG. 1B is a sectional view of a single crystal pulling apparatus.

[Explanation of symbols]

 1 Quartz Boat 2 Reaction Tube 3 Heater 4 Melt 5 Chamber 6 Quartz Crucible 7 Seed Crystal 8 Seed Crystal Attachment Jig 9 Heater 10 Melt 11 InSb Single Crystal

Claims (1)

[Claims] 1. A step of synthesizing an indium antimony polycrystal in an atmosphere of a gas composed of an element which becomes an electrically neutral impurity in the crystal, and gallium or gallium in the indium antimony polycrystal melt. A method for producing an indium antimony single crystal, comprising the step of adding a compound with a Group V element to perform single crystallization.