JP2001080989A - Compound semiconductor single crystal manufacturing apparatus and manufacturing method using the same - Google Patents

Abstract

(57) [Problem] To make it possible to obtain a long crystal and a large diameter crystal of a compound semiconductor single crystal with good reproducibility. A raw material melt and a liquid sealant are housed in a heated crucible 5 housed in a pressure vessel filled with an inert gas, and the seed crystal 11 and the crucible are brought into contact with the seed crystal 11 while being brought into contact with the raw material melt. 5 is relatively rotated to produce a compound semiconductor single crystal by the LEC method, and the ratio of the crystal to be grown to the diameter of the crucible {(crucible diameter) / (crystal diameter)} is 2.2 to 3.2. Use a crucible with a range of.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor single crystal manufacturing apparatus and a manufacturing method using the same.

[0002]

2. Description of the Related Art Group III-V compound semiconductors have been widely used in high-speed integrated circuits, opto-electronic integrated circuits and other electronic devices due to the improvement of single crystal quality. Above all, gallium arsenide (GaAs) has a feature that electron mobility is faster than silicon and a wafer having a specific resistance of 10 ⁷ Ω · cm or more can be easily manufactured. At present, the above semi-insulating G
The single crystal of aAs is mainly manufactured by the liquid sealing pulling method (LEC
Method).

FIG. 1 schematically shows a crystal pulling apparatus using the LEC method, which is widely used as a GaAs single crystal manufacturing apparatus.

In the figure, reference numeral 1 denotes a high-temperature furnace (pressure vessel) for crystal growth, in which a lower shaft 2 is inserted from below into a high-temperature furnace 1, and a susceptor is inserted into a tip of the lower shaft 2 through a pedestal 3. 4 are supported. A crucible 5 made of PBN is arranged in the susceptor 4. A heater 8 is provided around the susceptor 4.
Is provided, so that the PBN crucible 5 can be heated from the surroundings via the susceptor 4. The lower shaft 2 is connected to a rotation mechanism (not shown) and is rotated at a constant rotation speed. An upper shaft 9 is inserted coaxially with the lower shaft 2 from above the high-temperature furnace 1, and a seed crystal 11 having a desired orientation is placed in a seed crystal holder 10 provided at the lower end thereof (generally, (100 ) Is used. The upper shaft 9 is rotated by a rotating / elevating mechanism (not shown) in a direction opposite to that of the PBN crucible 5 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.

At the time of crystal growth, first, a PBN crucible 5
Ga, As6 (Ga7470g, As8124)
g) and 4,000 g of the B ₂ O ₃ liquid sealant 7, and the inside of the high-temperature furnace 1 is evacuated and then pressurized to about 40 atm with an inert gas such as nitrogen or argon, and the main heater 8 is energized. Then, the inside of the PBN crucible 5 is heated. 500 ℃
Before and after, the liquid sealant (B ₂ O ₃ ) 7 softens and melts, and G
a, Cover As6. Subsequently, the temperature is increased, the temperature inside the PBN crucible 5 is set to 1,238 ° C. or more, GaAs is synthesized, and further melted. 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 heater 8, the upper shaft 9 is pulled up at a speed of 7 to 12 mm / hr, and while detecting the crystal weight with the weight sensor 12, the output of the heater 8 is controlled to grow a GaAs single crystal. Let it.

The crucible 5 used in the LEC method is
BN (Pyrolitic Boron Nitride)
The crucible made of PBN is very expensive.
From this, the diameter of the crucible used in the LEC method is
Generally, a crystal slightly larger than the diameter of the crystal to be grown is used.

[0007]

However, the technique for growing a compound semiconductor single crystal is very difficult, and the arrangement and shape of members (called a hot zone, hereinafter referred to as HZ) such as a heater of a heating means and a heat shielding cylinder. It is difficult to obtain a good growth condition of the compound semiconductor single crystal with good reproducibility, because it is more minutely influenced by the material and the like.

In particular, the diameter of the compound semiconductor single crystal is 100 mm.
In the case of trying to obtain a large-diameter crystal exceeding, for example, it is very difficult to obtain particularly good reproducible compound semiconductor single crystal growth conditions, and in most cases, polycrystallization occurs during the process of single crystal growth, From the seeding part (seed part) of the crystal to the final part (tail part) of crystal growth, it was rare that a single crystal was obtained over the entire area.

Although not shown in FIG. 1, the high-temperature furnace 1 is provided with a member such as a heat shield tube (hot zone HZ). Until recently, the arrangement, shape, material, and the like of the HZ are compound semiconductors. It was considered to be a factor that affected the reproducibility of the single crystal growth conditions. However, with the stabilization of conditions such as the arrangement, shape, and material of the HZ, it has become clear that the factor is not only in the HZ but also in the characteristics of the PBN crucible used. Was. The crucible made of PBN is an indispensable tool especially for growing GaAs single crystals because of its advantages, such as the fact that Pyrolytic Boron Nitride itself does not react with the raw material compounds even at high temperatures for growing compound semiconductor single crystals and the purity of Pyrolytic Boron Nitride itself is high. , Its replacements are not known so far. Therefore, in order to improve the reproducibility of the growth conditions of the compound semiconductor single crystal and to improve the yield, it is essential to improve the characteristics of the PBN crucible. However, PB
It was not clear what was the most critical factor in the characteristics of the N crucible.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and a method for manufacturing a compound semiconductor single crystal capable of solving the above-mentioned problems of the prior art and obtaining a compound semiconductor single crystal with good reproducibility.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies on the production of compound semiconductor single crystals by the LEC method, and have obtained the following findings. That is, until recently, the factors for obtaining the growth conditions of the compound semiconductor single crystal with good reproducibility have been considered to be only related to the HZ arrangement, shape, material, etc., but the HZ arrangement, shape, material, etc. With the aim of stabilizing the above conditions, it has been discovered that the factor for obtaining a compound semiconductor single crystal with good reproducibility is not only in HZ but also in the diameter of the PBN crucible used.
Then, they have found that a compound semiconductor single crystal can be obtained with good reproducibility by defining the ratio of the diameters of the crucibles, and have reached the present invention.

That is, the apparatus for producing a compound semiconductor single crystal of the present invention is housed in a pressure-resistant container filled with an inert gas,
A raw material melt and a liquid encapsulant are stored in a heated crucible, and the seed crystal is brought into contact with the raw material melt, and the seed crystal and the crucible are relatively rotated to grow a single crystal by the LEC method. In the crystal manufacturing apparatus, the ratio of the diameter of the crystal to be grown and the diameter of the crucible {(crucible diameter) / (crystal diameter)} is set in the range of 2.2 to 3.2 (claim 1).

Further, according to the method for producing a compound semiconductor single crystal of the present invention, the compound semiconductor single crystal is housed in a pressure-resistant container filled with an inert gas,
A raw material melt and a liquid encapsulant are stored in a heated crucible, and the seed crystal is brought into contact with the raw material melt, and the seed crystal and the crucible are relatively rotated to grow a single crystal by the LEC method. In the method of manufacturing a crystal, a compound semiconductor single crystal is grown using a crucible having a ratio of a crystal to be grown to a crucible diameter {(crucible diameter) / (crystal diameter)} in the range of 2.2 to 3.2. (Claim 3).

In the manufacturing apparatus or the manufacturing method of the present invention, a crystal having a large diameter of 100 mm or more can be handled as a crystal to be grown.

The gist of the present invention is that, in the LEC method, the ratio of the diameter of the crystal to be grown to the crucible {(crucible diameter) / (crystal diameter)} is in the range of 2.2 to 3.2 so that reproducibility can be improved. This makes it possible to obtain a compound semiconductor single crystal with good and high yield. In the case of a large-diameter crystal in which the diameter of the crystal to be grown is 100 mm or more, the ratio of the crystal to be grown to the diameter of the crucible {(crucible diameter) / (crystal diameter)} is 2.
When the content is in the range of 2 to 3.2, a compound semiconductor single crystal can be obtained with higher reproducibility and higher yield.

The lower limit of the ratio of the diameter of the crystal to be grown to the crucible is set to 2.2 or more because the ratio of the diameter of the crystal to be grown to the crucible is less than 2.2.
e) and sub-grain boundaries are easily formed, the reproducibility of obtaining a single crystal is low, and the yield is naturally low. Lineage,
The reason that sub-grain boundaries are likely to be formed is presumed as follows. That is, in order to obtain a single crystal, the solid-liquid interface must always be convex toward the melt, but when the ratio between the diameter of the crystal to be grown and the diameter of the crucible is 2.2 or less, the solid-liquid interface is not stable. It is considered that a concave portion tends to occur on the melt side, and dislocations are concentrated, leading to the formation of lineage and sub-grain boundaries.

The reason why the upper limit of the ratio between the diameter of the crystal to be grown and the diameter of the crucible is set to 3.2 or less is that when the ratio of the diameter of the crystal to be grown to the diameter of the crucible exceeds 3.2, The fluctuation of the diameter is large, the reproducibility of obtaining a single crystal is low, and the yield is naturally low. The cause of the large fluctuation of the crystal diameter is presumed as follows. That is, L
Control of the crystal diameter by the EC method generally involves measuring the weight of a crystal grown per unit time, arithmetically processing the weight to calculate the crystal diameter, and controlling the output of a heater as a heating means. It is a target. If the ratio between the diameter of the crystal to be grown and the diameter of the crucible is too large, it is considered that the response to the diameter for controlling the output of the heater becomes slow, and the diameter of the crystal to be grown fluctuates greatly. . If the crystal diameter fluctuates drastically, the solid-liquid interface is not stable, and a concave portion is likely to be generated on the melt side, and dislocations are concentrated, leading to the formation of lineage and sub-grain boundaries.

In the case of a large-diameter crystal having a crystal diameter of 100 mm or more to be grown, the importance of the solid-liquid interface is naturally larger than that of the small-diameter crystal, and it is necessary that the solid-liquid interface be stably convex toward the melt.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described mainly with reference to examples. Here, an embodiment applied to the production of gallium arsenide, which is a kind of compound semiconductor, will be described. The manufacturing apparatus used in the following Examples 1 to 4 and Comparative Examples 1 to 4 is the same as that shown in FIG. 1, and is heated in a high-temperature furnace 1 which is a pressure-resistant container filled with an inert gas and heated. And the crucible 5 was relatively rotated while the seed crystal 11 was in contact with the raw material melt, and a compound semiconductor single crystal was manufactured by the LEC method. In Examples 1 to 4, a crucible having a ratio K = {(crucible diameter D) / (crystal diameter d)} of the crystal to be grown and the crucible in the range of 2.2 to 3.2 was used.

Table 1 shows the contents of Examples 1 to 4 and Comparative Examples 1 to 4.

[0021]

[Table 1]

[Embodiments 1-2] P having a diameter of 280 mm
Using a BN crucible, crystal diameter 100 mm, crystal length 4
Single crystal growth of 00 mm gallium arsenide was performed 50 times (Example 1). As a result, a 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.

The diameter of the PBN crucible is 220 mm or more.
Using a crucible in the range of 320 mm, a crystal diameter of 10
Gallium arsenide single crystal growth of 0 mm and a crystal length of 400 mm was performed 200 times (Example 2). As a result, a single crystal in the entire region was obtained with a probability of 90% or more.

[Examples 3 and 4] Single crystal growth of gallium arsenide having a crystal diameter of 150 mm and a crystal length of 300 mm was performed 20 times using a PBN crucible having a diameter of 400 mm (Example 3). As a result, a single crystal in the entire region was obtained with a probability of 80% or more.

The PBN crucible has a diameter of 330 mm or more.
Using a crucible in the range of 480 mm, the crystal diameter is similarly 15 mm.
Gallium arsenide single crystal growth of 0 mm and a crystal length of 300 mm was performed 50 times (Example 4). As a result, a single crystal in the entire region was obtained with a probability of 75% or more.

[Comparative Examples 1-2] As a result of growing a single crystal of gallium arsenide having a crystal diameter of 100 mm and a crystal length of 400 mm using a PBN crucible having a diameter smaller than 220 mm, lineage and sub-grain boundaries were generated. The probability of obtaining a single crystal in the entire region was 70% or less (Comparative Example 1). Note that the probability of obtaining a single crystal in the entire region tended to decrease as the diameter of the crucible became smaller.

Further, a single crystal of gallium arsenide having a crystal diameter of 150 mm and a crystal length of 300 mm was grown using a PBN crucible having a diameter of less than 330 mm.
As in the case of 0 mm, the probability of obtaining a single crystal in the entire region due to generation of lineage and sub-grain boundaries was 60% or less (Comparative Example 2).

[Comparative Examples 3 and 4] As a result of growing a single crystal of gallium arsenide having a crystal diameter of 100 mm and a crystal length of 400 mm using a PBN crucible having a diameter larger than 320 mm,
The crystal diameter fluctuated drastically, lineage and sub-grain boundaries were generated during the growth, and the probability of obtaining a single crystal in the entire region was less than 75% (Comparative Example 3). Note that the probability of obtaining a single crystal in the entire region tended to decrease as the diameter of the crucible increased.

Further, a single crystal of gallium arsenide having a crystal diameter of 150 mm and a crystal length of 300 mm was grown using a PBN crucible having a diameter larger than 480 mm.
In the case of 0 mm, the crystal diameter fluctuated greatly, lineage and sub-grain boundaries were generated during the growth, and the probability of obtaining a single crystal in the entire region was 65% or less (Comparative Example 4).

Summing up the above results, the crystal diameter to be grown is determined when the ratio K = {(crucible diameter D) / (crystal diameter d)} of the crystal to be grown is in the range of 2.2 to 3.2. It can be seen that by selecting the crucible diameter, it becomes possible to obtain a compound semiconductor single crystal with good reproducibility and high yield. In the case of a large-diameter crystal in which the diameter d of the crystal to be grown is 100 mm or more, the ratio K between the diameter of the crystal to be grown and the diameter of the crucible is K.
= {(Crucible diameter D) / (crystal diameter d)} = 2.2
By setting the range of 3.2, a compound semiconductor single crystal can be obtained with higher reproducibility and higher yield.

In the above embodiment, gallium arsenide (GaAs) is used.
Although the case where a single crystal is grown has been described, the present invention can be applied to a manufacturing apparatus and a manufacturing method of a compound semiconductor single crystal in which crystal growth is performed by an LEC method such as InP, GaP, and InAs. Obtainable.

The compound semiconductor single crystal obtained by the method and the apparatus according to the present invention not only has a higher probability of obtaining an entire area single crystal than the conventional method, but also has a high possibility of obtaining a compound semiconductor single crystal obtained by the conventional method. In comparison, the number of dislocation accumulation parts tends to be small. This indicates that, in the case of the conventional method, dislocations accumulate even if the entire area is a single crystal, even if it does not develop into lineage and sub-grain boundaries. When a compound semiconductor wafer obtained by the present invention is used to form a device, it is possible to prevent a decrease in device yield due to dislocation. The economic effects on industrial production are enormous.

[0033]

As described above, according to the present invention, the ratio of the diameter of the crystal to be grown to the diameter of the crucible ｛(crucible diameter) /
(Crystal diameter) so that｝ falls in the range of 2.2 to 3.2,
Since the diameter of the crystal to be grown and the diameter of the crucible are selected, a compound semiconductor single crystal can be obtained using the LEC method with good reproducibility and high yield. Therefore, a long crystal and a large diameter crystal of the compound semiconductor single crystal can be obtained with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a compound semiconductor single crystal manufacturing apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High temperature furnace 5 PBN crucible 6 Ga, As 7 Liquid sealant 8 Heater 11 Seed crystal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Oba 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Prefecture Inside the Hidaka Plant, Hitachi Cable Co., Ltd. F-term (reference) at Hitachi Cable, Ltd. Hidaka Factory 4G077 AA02 AB09 BE46 CF10 EG01 EJ07 5F053 AA12 AA13 BB35 BB60 DD03 DD20 FF04 GG01 HH04 LL10 RR03 RR04

Claims (4)

[Claims] A raw material melt and a liquid sealant are stored in a heated crucible contained in a pressure vessel filled with an inert gas, and the seed crystal and the crucible are brought into contact with the seed crystal while being brought into contact with the raw material melt. Is relatively rotated to grow a single crystal, the ratio of the crystal to be grown to the crucible {(crucible diameter) / (crystal diameter)} is 2.2 to 3 2. An apparatus for producing a compound semiconductor single crystal, which is defined in the range of 2. 2. The compound semiconductor single crystal manufacturing apparatus according to claim 1, wherein the crystal to be grown is a large-diameter crystal having a diameter of 100 mm or more. 3. A raw material melt and a liquid sealing agent are stored in a heated crucible housed in a pressure vessel filled with an inert gas, and the seed crystal and the crucible are placed in contact with the seed crystal. Is relatively rotated to grow a single crystal, the ratio of the crystal to be grown to the crucible {(crucible diameter) / (crystal diameter)} is set to 2.2 to 3 2. A method for producing a compound semiconductor single crystal, comprising growing a compound semiconductor single crystal using a crucible defined in the range of 2. 4. The method for producing a compound semiconductor single crystal according to claim 2, wherein a large-diameter crystal having a diameter of 100 mm or more is grown.