JPS6114193A - Manufacture of compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To obtain the titled high-quality single crystal by using a liquid sealant having less than a specified value resistivity for sealing to stop simultaneously the convection in the material melt and in the sealant and to stabilize the thermal environment. CONSTITUTION:A magnetic field is impressed on a high-pressure chamber 1 by a magnetic field impressing device at the outside. A crucible 3 contg. a liquid sealant consisting of B2O3 mixed with Ga, As, and a metallic oxide such as SnO2 and having <=1,000OMEGA.cm resistivity, is mounted on a crucible supporting shaft 2 in the chamber 1. After the inside of the chamber 1 is pressurized with gaseous Ar, the crucible 3 is heated by a cylindrical heater 4 surrounding the crucible 3 concentrically, and two layers of GaAs melt 5 and said liquid sealant melt 16 covering the melt 5 are obtained. Then a seed crystal 8 attached to the leading end of a crystal pulling shaft 7 is passed through the liquid sealant 16, brought into contact with the GaAs melt 5, and pulled up while rotating the shaft 7 to obtain a high-quality chemical semiconductor GaAs single crystal 9.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for producing a compound semiconductor single crystal by a magnetic field application liquid-sealed Czyocholarski method, and in particular a method for producing a compound semiconductor single crystal for producing a high quality single crystal. This invention relates to a method for producing crystals.

[Technical background of the invention and its problems]

Compound semiconductor single crystals such as GaP, GaAs, and InP are important materials for autoelectronics and microelectronics, and the liquid encapsulation Ctyocholarski method (hereinafter referred to as LEO method) is an industrial manufacturing method for these semiconductor single crystals. ) is known.

One of the methods for manufacturing high-quality single crystals using this LEO method is the method of manufacturing single crystals by the LEO method while applying a magnetic field (magnetic field applied liquid seal Czyochoralski method, hereinafter referred to as MLBO method). This MLEO method is basically the LBO method with the addition of a magnetic field application device.For example, quartz or pyrolytic poron nitride (hereinafter abbreviated as PBN) is placed on the crucible supporting shaft (■) in the high-pressure chamber (■). omit)
A crucible made of
In the case of GaAs single crystal production, Ga and As are filled, and a liquid sealing agent such as boron oxide (B) is added thereto.

03). This crucible is heated with a heater (2) surrounding the crucible in a coaxial cylindrical shape to form two layers of GaAs melt (2) and a sealing agent covering the surface thereof. At this time, the inside of the chamber is pressurized with an inert gas, such as argon gas. In this way, the decomposition and scattering of the raw materials are prevented, and in this state, the seed crystal attached to the tip of the crystal pulling shaft ■ is passed through the sealant, brought into contact with the GaAβ melt, and pulled up while rotating. to create a single crystal ■. This is done using the normal L'IO method, but in the MLEO method, a magnetic field generator [phase] is installed around this high-pressure chamber to apply a magnetic field to the crystal raw material melt in the crucible in the crystal creation furnace. A single crystal is created while applying a magnetic field using this magnetic field generator.

T. When creating a compound semiconductor using the 1180 method, large thermal convection occurs in the externally heated crystal raw material melt and sealant, which causes the temperature at the solid-liquid interface where the crystal grows to fluctuate. . Such temperature fluctuations lead to fluctuations in crystal growth rate and crystal re-melting and solidification, resulting in decreased crystallinity, 9 or non-uniform impurity concentration. The MLEO method focuses on the fact that the semiconductor melt has an electric charge and that this electric charge flows according to thermal convection.By applying an external magnetic field, it focuses on the fact that the electric charge is flowing. By adding , a force is applied to the charge in the opposite direction to the convection, and this force and the flow due to convection cancel each other out, stopping the melt convection, and this effect stops the fluctuation of the temperature at the solid-liquid interface during crystal growth. This is a method for creating high-quality single crystals. .

However, even in this MLEO method, since B or 03 with low electrical conductivity is used as the sealant, convection in the raw material melt with large electrical conductivity stops even when a magnetic field is applied. O, the convection inside cannot be stopped. B20. The presence of convection causes temperature fluctuations at the interface between the semiconductor melt and the B,03 melt, which causes fluctuations in the temperature at the solid-liquid interface where crystals grow. Similar to when no magnetic field is applied, this temperature fluctuation can lead to fluctuations in the crystal growth rate, crystal re-melting and solidification, decreased crystallinity, non-uniform impurity concentration, or changes in the crystal plane. Dislocations become uneven.

[Purpose of the invention]

In view of the above-mentioned drawbacks, the present invention manufactures high-quality compound semiconductor single crystals by simultaneously stopping not only the conventional melt of the raw material but also the convection in the sealant using the magnetic field application liquid sealing Czyochoralski method. To provide a method for Vc.

[Summary of the invention]

An overview of the present invention will be given by taking the production of a GaAs single crystal as an example.
, will be explained with reference to the figures.

・The method for producing a GaAs single crystal using the MLEIO method will be explained according to FIG.

The crucible ■ containing Ga, As, and sealants OB and 03 is mounted on the crucible support shaft ■ in the high-pressure chamber ■, and the crucible is heated with a heater ■ that surrounds the crucible in a coaxial cylindrical shape.
A two-layer state of B and 03 melt [phase] is created by mixing the melt ■ and tin dioxide (Snow) covering the GaAs melt.

At this time, the inside of the high-pressure chamber (2) is pressurized with argon gas. This GaAs and 8n02 are mixed, the B2O3 is made into a melt state, and a seed crystal (2) attached to the tip of the crystal pulling shaft (2) is passed through the B2O3 melt mixed with 8nO to form the GaAs melt. The crystals are brought into contact with each other and pulled up while rotating the crystal pulling shaft (■) to obtain a GaAs single crystal (■). At this time, a magnetic field is applied to the portion where the GaAs single crystal is being formed using a magnetic field application device installed outside the high-pressure chamber, as in the conventional case.

Figure 2 VC shows a diagram under the same conditions as shown in Figure 7, with a few thermocouples (2) attached instead of nine seed crystals (2) attached to the crystal pulling shaft (2). This thermocouple is connected to GaAs melt ■, B
, O, when a magnetic field is applied to the melt ■, and when it is applied,
We observed temperature fluctuations in the absence of this.

The results are shown in Figure 3 ((a) is the sealant, (b) is the G
a A s melt).

As shown in FIG. 3, conventional B, 0. When used together with a sealant, even if moderate fluctuations in the top of the GaAs melt decrease, almost no change is observed in the sealant. This is B
20. The resistance of the melt is high and it is B at room temperature! Oa melt is 106
Ga
This is because it has a much higher resistance than As.

Therefore, the present invention uses tin dioxide (Sn01) as described above.
B mixed with B! When the 03 melt [phase] is used as a sealant, the resistivity of this sealant at room temperature is 100Ω. Temperature fluctuations were observed using a method similar to that shown in FIG. The results are shown in Figure 4 (Figure (a) is the sealant, c)
is a GaAs melt). - The temperature fluctuation in the sealant can now be reduced to almost the same level as the temperature fluctuation in the GaAs melt.

Next, in order to investigate the relationship between the temperature fluctuation of the sealant and the resistivity of the sealant, 8nO1 and Nano were added to the B2O3 melt.

In103, Ga2O3, A71!103, K
, O, etc. were mixed, and the relationship between resistivity at room temperature and temperature fluctuation in the sealant melt was investigated. Here, the temperature fluctuation of the sealant indicates the difference between the maximum temperature and the minimum temperature when the external thermal environment is kept constant. The results are shown in FIG. As is clear from this figure, the temperature fluctuation rapidly decreases after reaching 1000Ω, and the resistivity of the sealant is Filo00Ω・α.
It was found that temperature fluctuations can be reduced by applying a magnetic field if the temperature is set as follows.

In this way, the present invention uses B as a sealant in the MLEO method.
This method of manufacturing a semiconductor single crystal is characterized in that resistivity is lowered and temperature fluctuations in the sealant melt are reduced by mixing an appropriate metal oxide with 2O2.

〔Effect of the invention〕

When a single crystal is created by the MLEO method according to the present invention, the convection of the sealant is simultaneously suppressed, so the thermal environment is stabilized, and this traps a compound semiconductor-single crystal with low dislocations and a uniform impurity concentration. can be created.

[Embodiments of the invention]

An embodiment of the present invention will be explained using GaAs as an example.
First, a method for producing a GaAs single crystal using the MLEO method will be explained with reference to FIG.

Fill the high pressure chamber ■ with Ar gas and support the crucible shaft ■
To the crucible made of PBN with an inner diameter of 96φ attached to the
500. lil, As 550g and BtO3150#
and 8n02101-ln2C) 110g,
Heat with heater ■ to form Ga As melt ■ and sealant [phase]
It was made into a two-layer state. The resistivity of this sealant is 480 at room temperature.
・It was me. At this time, a magnetic field application device [phase] is applied to the crucible.
A magnetic field of 300 oersted is applied, and in this state, a seed crystal in the <Zoo> direction attached to the tip of the crystal pulling shaft (■) is attached to the GaAs melt (■), and a G magnet of 50 m in diameter and 100 m in length is attached.
A As single crystal ■ was obtained. Slice this crystal (
100) A wafer was made and etched using the molten KOH etching method to determine the dislocation distribution.

FIG. 6 shows the results of single crystals obtained by the ML and BO methods according to the present invention and the results obtained by the conventional MLEO method.

@ indicates the dislocation density distribution by the conventional MLEO method, and 0 indicates the dislocation density distribution by the MLBO method using the present invention.

As described above, it has been found that by using the present invention, the thermal environment in the sealant is stabilized, and in particular, the dislocation density in the peripheral area of the crystal is significantly reduced.

As described above, high quality single crystals can be produced by lowering the electrical resistance of B2O2.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram for explaining the MLEO method that outlines the present invention, Fig. 2 is a diagram showing a method for measuring melt temperature, and Figs. A diagram of temperature fluctuation in the sealant melt; Figure 5 is a diagram of the correlation between the resistivity of the sealant and temperature fluctuation;
Figure 6 shows the dislocation density distribution, Figure 7 shows the conventional MLE.
This is a schematic diagram for explaining the O method. ■：High-pressure cha/ba, ■Nil acupuncture support shaft, ■Nil acupuncture point,
■: Heater, ■: Crystal raw material melt, ■: B, 03 melt,
■: Crystal pulling axis, 02 seed crystal, ■: Single crystal, [phase]:
Magnetic field application device, ■: Thermocouple, @: Dislocation density distribution line by conventional MLEO method, @: Dislocation density distribution line by MLEO method according to the present invention, [Phase]: B, Os mixed with 8nO, etc.
Melt. Agent: Patent Attorney Noriyuki Kenshi (and 1 other person) No. 1
Figure 2 Figure 8 (Q) Cb] Figure 4 (0L) Stone to Horse (Arashi 4 Tomorrow 5 @1 .tashin Ω, C 匍 Figure 6

Claims (3)

[Claims] (1) A method for manufacturing a compound semiconductor single crystal by a magnetic field applied liquid sealing Czyochoralski method, wherein the liquid sealant has a resistivity of 1000 Ω·cm or less at room temperature. Method for producing single crystals. (2) The compound semiconductor monomer according to claim 1, wherein the liquid sealant is one or a mixture of two or more of diboron trioxide and metal oxides other than diboron trioxide. Method of manufacturing crystals. (3) The metal oxide is at least one of tin dioxide, indium oxide, aluminum oxide, gallium oxide, phosphorus pentoxide, sodium oxide, potassium oxide, and calcium oxide.
Claim 2, characterized in that the oxide is
A method for producing a compound semiconductor single crystal as described in 1.