JP2004244233A - Method of manufacturing gallium arsenide single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a gallium arsenide single crystal in a high yield with a good reproducibility by a liquid encapsulating Czochralski method, a vertical boat method or a horizontal boat method. <P>SOLUTION: In a method for manufacturing the gallium arsenide single crystal by the liquid encapsulating Czochralski method, the vertical boat method or the horizontal boat method, using Ga and As raw materials, Ga in which the ratio of isotope<SP>69</SP>Ga (Ga of mass number 69) or<SP>71</SP>Ga (Ga of mass number 71) is increased to be ≥90% is used as the Ga being one raw material of the gallium arsenide single crystal. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a gallium arsenide (GaAs) single crystal by using a raw material Ga and As by a liquid sealing pulling method, a vertical boat method, or a horizontal boat method.
[0002]
[Prior art]
Conventionally, as a technique for producing gallium arsenide (GaAs) single crystal using raw materials Ga and As, a PBN container containing a raw material melt is arranged in a high-temperature furnace, and a seed crystal is brought into contact with the raw material melt. A liquid sealing pulling method (LEC method) in which a single crystal is grown by relatively moving a seed crystal and a PBN container while growing a single crystal, or a seed crystal is arranged under a vertical boat, and the crystal is grown in this boat. A vertical boat method in which a seed crystal is arranged in a horizontal boat and a crystal is grown in the boat is known.
[0003]
FIG. 1 schematically shows a crystal pulling apparatus using the LEC method, which is widely used as a GaAs single crystal growth apparatus.
[0004]
In the figure, reference numeral 1 denotes a high-temperature furnace (pressure-resistant vessel) for crystal growth, into which a lower shaft 2 is inserted from below, and a susceptor 4 is supported at the tip of the lower shaft 2 via a pedestal 3. Have been. In the susceptor 4, a crucible 5 made of pyrolytic boron nitride (PBN) is arranged. A heater 8 is provided around the susceptor 4 so that the PBN crucible 5 can be heated from the surroundings through the susceptor 4. The lower shaft 2 is connected to a rotation / elevation mechanism (not shown), and is rotated at a constant rotation speed. An upper shaft 9 is inserted coaxially with the lower shaft 2 from the upper side of the container 1, and a seed crystal 11 having a desired orientation is placed in a seed crystal holder 10 provided at the lower end thereof (usually (100) as the orientation). Is used) is attached. The upper shaft 9 is rotatable relative to the PBN crucible 5 by a rotating / elevating mechanism (not shown), and is moved up and down. A weight sensor 12 is provided in the middle of the upper shaft 9 so that the weight of the crystal during the growth process can be detected.
[0005]
At the time of crystal growth, first, 14,000 g of the GaAs polycrystalline raw material 6 and 4,000 g of boron trioxide (B ₂ O ₃ ) as the liquid sealant 7 are put in the crucible 5 made of PBN. The inside of the crucible 5 is evacuated, then pressurized to about 40 atm with an inert gas such as nitrogen or argon, and energized to the main heater 8 to heat the inside of the PBN crucible 5. At about 500 ° C., the liquid sealant (B ₂ O ₃ ) 7 softens and melts to cover the GaAs polycrystalline raw material 6. Then, the temperature inside the PBN crucible 5 is increased to 1,238 ° C. or higher to melt the polycrystalline raw material 6. Next, after the pressure in the high-temperature furnace 1 is reduced to 5 to 20 atm, the seed crystal 11 is lowered, and its tip is immersed in a raw material melt to perform seeding. Thereafter, while lowering the temperature of the main heater 8, the upper shaft 9 is pulled up at a speed of 9 to 12 mm / hr, and while detecting the crystal weight with the weight sensor 12, the output of the main heater is controlled to remove the GaAs single crystal. Let it grow.
[0006]
When the GaAs single crystal is grown, it is general to control the shape of the solid-liquid interface to be convex toward the melt side in order to prevent dislocation aggregation since the crystal is a dislocation crystal. Many ideas have been proposed for that purpose. For example, in the vertical Bridgman method, which is a type of vertical boat method, a material having a low thermal conductivity is used in a portion near a heater near a seed crystal under a crucible, and a material having a high thermal conductivity is used in a portion near a seed crystal. There has been proposed a method of installing a shield (see Patent Document 1).
[0007]
[Patent Document 1]
JP-A-5-238870 (FIG. 1)
[0008]
[Problems to be solved by the invention]
As described above, as a method for producing gallium arsenide single crystal, techniques such as a horizontal boat method, a liquid sealing pulling method, and a vertical board method are generally adopted, where they are used as a raw material for gallium arsenide single crystal. Gallium contains isotopes of ⁶⁹ Ga and ⁷¹ Ga at a ratio of about 60.2% and about 39.8%, respectively.
[0009]
However, as long as such a gallium raw material is used, the yield of obtaining a single crystal is not good in any of the methods. One of the major reasons for the poor yield is that gallium arsenide is a dislocation crystal. Therefore, it is necessary to make the solid-liquid interface always and entirely convex toward the melt during the growth process. It is.
[0010]
Therefore, an object of the present invention is to solve the above-described problems and to use ⁶⁹ Ga or ⁷¹ Ga, which is an isotope of gallium, separately, by a liquid sealing pulling method, a vertical boat method or a horizontal boat method, An object of the present invention is to provide a manufacturing method capable of obtaining a gallium arsenide single crystal with good reproducibility and high yield.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0012]
A method for producing a gallium arsenide single crystal according to the invention of claim 1 is a method for producing a gallium arsenide single crystal using a raw material Ga or As by a liquid sealing pulling method, a vertical boat method or a horizontal boat method. Is characterized in that, as gallium as one raw material of the gallium arsenide single crystal, isotope ⁶⁹ Ga (69 gallium mass number) is used at a ratio of 99.9% or more.
[0013]
A method for producing a gallium arsenide single crystal according to the invention of claim 2 is a method for producing a gallium arsenide single crystal using a raw material Ga or As by a liquid sealing pulling method, a vertical boat method or a horizontal boat method. Is characterized in that isotope ⁷¹ Ga (mass 71 gallium) is used at a rate of 99.9% or more as gallium as one raw material of the gallium arsenide single crystal.
[0014]
<The gist of the invention>
The gist of the present invention is that gallium, which is one raw material of gallium arsenide single crystal, isotope ⁶⁹ Ga (mass number 69 gallium) or ⁷¹ Ga (mass number 71 gallium) at a ratio of 99.9% or more. Thus, it is possible to obtain a gallium arsenide single crystal with good reproducibility and high yield.
[0015]
Gallium used as a raw material of gallium arsenide single crystal contains isotopes of ⁶⁹ Ga and ⁷¹ Ga at a ratio of about 60.2% and about 39.8%, respectively. Therefore, in the present invention, ⁶⁹ Ga and ⁷¹ Ga, which are isotopes of gallium, are separated from each other, and one of them is used at a ratio of 99.9% or more, thereby improving the thermal conductivity and making the solid-liquid interface convex. By doing so, the yield is improved.
[0016]
The reason for increasing the proportion of the same isotope of gallium, which is one of the raw materials of the gallium arsenide single crystal, to 99.9% or more is that when the proportion of the same isotope is increased to 99.9% or more, the crystal is grown. This is because the thermal conductivity of the gallium compound semiconductor crystal is greatly improved. When the thermal conductivity of the gallium arsenide compound semiconductor crystal is improved, heat is easily released from the crystallized portion in the crystal growth process, and the solid-liquid interface is constantly and entirely convex in the growth process. It becomes easy to do.
[0017]
It should be noted that the exact value of the thermal conductivity improvement ratio when the ratio of the same isotope is set to 99.9% or more is not known. However, as compared with the case where the proportion of the same isotope is less than 99.9%, it is confirmed that the thermal conductivity of the gallium arsenide compound semiconductor crystal is greatly improved. It is easy to make the solid-liquid interface always and entirely convex toward the melt, thereby greatly improving the yield of obtaining a gallium arsenide single crystal.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the method for producing a gallium arsenide single crystal of the present invention will be described with a focus on an example using the LEC method.
[0019]
The manufacturing apparatus used in the following Examples 1 and 2 and Comparative Examples 1 and 2 is the same as that in FIG. 1. First, arsenic (As) and gallium (Ga), which are raw materials, and B ₂ O ₃ Is stored, and in a pressure-resistant container filled with an inert gas, a GaAs melt is formed by heating means, and seeding and crystal growth are performed. However, as the gallium as one raw material of the gallium arsenide single crystal, isotope ⁶⁹ Ga (mass number 69 gallium) or ⁷¹ Ga (mass number 71 gallium) is used at a rate of 99.9% or more.
[0020]
[Example 1]
In a liquid sealing pulling method, which is a method of manufacturing a gallium arsenide compound semiconductor single crystal, a PBN crucible having a diameter of 280 mm is used to form a gallium arsenide compound semiconductor single crystal having a crystal diameter of 100 mm and a crystal length of 400 mm. Manufacturing was performed.
[0021]
As the gallium which is one raw material of gallium arsenide single crystal, the raw material using a ^{69 Ga} at a ratio of more than 99.9%, it was performed 50 times the production of a gallium arsenide compound semiconductor single crystal. As a result, an entire single crystal (All Single) was obtained with a probability of 95% or more from the seeding of the crystal to the final part of the crystal growth.
[0022]
[Example 2]
Also, the ^{71 Ga} Similarly the raw material used in the proportion of 99.9% was carried out 50 times the production of a gallium arsenide compound semiconductor single crystal. As a result, an entire single crystal (All Single) was obtained with a probability of 95% or more from the seeding of the crystal to the final part of the crystal growth.
[0023]
[Comparative Example 1]
As Comparative Example 1, as in the example, gallium arsenide was used as a gallium as one raw material of the gallium arsenide single crystal by a liquid sealing pulling method using ⁶⁹ Ga at a ratio of less than 99.9%. Production of a compound semiconductor single crystal was performed 50 times. As a result, from the seeding of the crystal to the final part of the crystal growth, the probability of the single crystal (All Single) was 90% or less.
[0024]
[Comparative Example 2]
As also Comparative Example 2, a ^{71 Ga} Similarly, in materials used in a proportion of less than 99.9%, was carried out 50 times the production of a gallium arsenide compound semiconductor single crystal. As a result, from the seeding of the crystal to the final part of the crystal growth, the probability of the entire single crystal (All Single) was 90% or less.
[0025]
Note that the probability of the entire single crystal (All Single) is correlated with the ratio of the single isotope of the isotope. As ⁶⁹ Ga and ⁷¹ Ga become closer to about 60.2% and about 39.8%, respectively, The lower the value, the lower the tendency. The reason that the probability of the single crystal was lowered is that the solid-liquid interface is not always convex on the melt side and is concave on the melt side in the growth process, so that the transition is concentrated, and the lineage, This is due to the occurrence of sub-grain boundaries.
[0026]
The gallium arsenide compound semiconductor crystal obtained by the manufacturing method of the present embodiment not only has a higher probability of an all single crystal (All Single) than the conventional method, but also has a higher probability than the gallium arsenide compound semiconductor single crystal obtained by the conventional method. The dislocation accumulation part tended to be small. This indicates that in the case of the conventional method, even in the case of an all single crystal (All Single), dislocations accumulate even if they do not develop into lineage and sub-grain boundaries.
[0027]
When a device is formed using the gallium arsenide compound semiconductor wafer obtained in the present embodiment, it is possible to prevent a reduction in device manufacturing yield due to dislocation. Therefore, the economic effects in industrial production are enormous.
[0028]
<Other Embodiments and Modifications>
In the above embodiment, the liquid sealing pulling method is described as a method of manufacturing a gallium arsenide compound semiconductor single crystal, but the present invention is not limited to the pulling method. It is the same in the horizontal boat method and the vertical boat method that the solid-liquid interface is always and entirely convex on the melt side in the growth process. With the horizontal boat method and the vertical boat method, the same effects as in the above embodiment can be obtained.
[0029]
In addition, the present invention can be applied to a method of manufacturing another transferable compound semiconductor crystal such as GaP, and the same effect can be obtained.
[0030]
【The invention's effect】
As described above, according to the method for producing a gallium arsenide single crystal of the present invention, as a gallium as one raw material of the gallium arsenide single crystal, isotope ⁶⁹ Ga (mass 69 gallium) or ⁷¹ Ga (mass 71 gallium) is used. By using (gallium) at a rate of 99.9% or more, the reproducibility of single crystal growth conditions can be improved, and a gallium arsenide single crystal can be manufactured with high yield.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration of a manufacturing apparatus used in a method for manufacturing a gallium arsenide single crystal according to the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 high temperature furnace 3 pedestal 4 susceptor 5 crucible made of PBN 6 polycrystalline raw material 7 liquid sealant (B ₂ O ₃ )
11 seed crystal

Claims (2)

In a method of manufacturing a gallium arsenide single crystal using a raw material Ga, As by a liquid sealing pulling method, a vertical boat method or a horizontal boat method to manufacture a gallium arsenide single crystal,
A method for producing a gallium arsenide single crystal, characterized in that, as gallium as one raw material of the gallium arsenide single crystal, isotope ⁶⁹ Ga (mass number 69 gallium) is used at a rate of 99.9% or more. In a method of manufacturing a gallium arsenide single crystal using a raw material Ga, As by a liquid sealing pulling method, a vertical boat method or a horizontal boat method to manufacture a gallium arsenide single crystal,
A method for producing a gallium arsenide single crystal, characterized in that isotope ⁷¹ Ga (mass 71 gallium) is used at a rate of 99.9% or more as gallium as one raw material of the gallium arsenide single crystal.

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