JPS58156600A - Preparation of 3-5 group semiconductor crystal - Google Patents

Abstract

PURPOSE:To prevent the diffusion of raw materials during the growth of a semiconductor crystal from molten liquid, by putting a III-group raw material, a V-group raw material and a III-V group compound raw material in a crucible, heating the crucible to melt the III-V group compound raw material, and covering the surface with inert molten material. CONSTITUTION:A crucible 7 containing Ga as the III-group raw material, As as the V-group raw material, GaAs compound as the III-V group compound raw material, and B2O3, is placed in a pressure vessel 1, and heated under the pressure of an inert gas to form a molten mixture composed of Ga, As and GaAs compound and covered with molten B2O3. The temperature is further raised to cause the reaction of Ga with As, and a part of the heat of reaction is allowed to be absorbed in the GaAs compound to effect the moderate reaction. After the completion of the reaction, the temperature is further raised to form the GaAs molten liquid, to which the lower end of the seed crystal is made to contact and pulled up to obtain the objective GaAs compound semiconductor single crystal 5.

Description

[Detailed Description of the Invention] The present invention relates to a method for manufacturing a ■-■ group compound semiconductor crystal,
In particular, the present invention relates to an improvement in the manufacturing method using the direct synthetic liquid capsule pulling method.

Conventionally, a pulling apparatus as shown in FIG. 1 has been used to manufacture group IX-III compound semiconductors mainly made of GaAs, GaP, InP, etc. In the figure, 1 is a pressure vessel;
2 is a melt of the ■-■ group compound, and 3 is a melt that is inactive with respect to the melt 2, and B2O3 is usually used. Numeral 4 is a seed crystal, which is brought into contact with the melt 2 and then pulled up while being rotated to obtain a grown compound crystal 5 of the 1-2 group. In addition, 6 is a rotating shaft of the seed crystal, 7 is a crucible, 8 is a susceptor that accommodates and supports the crucible 7, 9 is a heater that heats the crucible 7, 10 is a heat insulating material, and 11 is a rotating shaft that supports the susceptor 9. be.

Seed crystal 4 was manufactured by boat growth method or zone melting method■-■
Group compound crystals are used, but recently, with the aim of obtaining high electrical resistivity, group II raw materials and group II raw materials are directly charged into crucible 7, and the two are reacted under high pressure to form a group I and ■-■ compound. A method called the direct synthesis liquid capsule pulling method, in which the compound is grown by pulling it from the melt after it has been made, has begun to be used. According to this method, the incorporation of impurities is extremely reduced compared to other methods, so it is possible to obtain a so-called intrinsic semiconductor with high electrical resistance.
It is a suitable material for SI.

' In this case, many of the group V raw materials generally have extremely high vapor pressure at the reaction temperature with the group (2) raw materials, and the reaction is normally suppressed by suppressing the inert melt 3 with high-pressure inert gas from outside. Attempts have been made to prevent the volatilization of group Ⅰ elements and to maintain the stoichiometric composition of the reaction product. For example, the vapor pressure at the temperature at which the Group (1) element As reacts with Ga reaches about 20 atm for As and about 40 atm for P, so the atmospheric gas pressure needs to be about 80 to 100 atm. .

However, it was observed that during the reaction, group V elements were volatilized and the stoichiometric composition of the melt was shifted.

This is thought to be because the reaction between the group Ⅰ element and the group Ⅰ element is extremely fast, and the heat of the reaction instantaneously raises the temperature of the raw material, releasing a high-pressure gas consisting of the group Ⅰ element.

To prevent this, it is necessary to make the atmospheric gas even higher pressure. However, this requires increasing the size of the device and increasing the output of the heat source, which poses technical difficulties. Another possible method is to thicken the inert melt 3, but this involves difficulties during pulling growth. In addition to the above-mentioned difficult problem of maintaining the stoichiometric composition, not only the direct synthesis liquid capsule method but also the general liquid capsule method in which crystals of ■-■ group compounds are pulled, the residue of compounds with deviations in the stoichiometry composition is generated. The problem is that this occurs. Conventionally, there was a problem in that there was no effective way to utilize the residue, resulting in a waste of resources.

The purpose of the present invention is to provide a method for manufacturing a group IV compound semiconductor crystal that can solve the problems of the prior art as described above and make resources more efficient.The present invention is characterized by: −■ Group compound melt is mixed with ■ group raw material and ■ group raw material ■
- It is a molten mixture of group compound raw materials.

To explain the production method of the present invention using GaAs as an example, in the conventional direct synthesis liquid capsule method, Ga and an equivalent amount of As and B2O3 are placed in a crucible 7 and heated to produce Ga and As at about 700 to 800°C. Let it react, but
The reaction at this time is rapid and the temperature around the raw material rises in an instant. Even if this is suppressed and the raw material is protected around it with a B2O3 melt and further pressurized with gas at 60 to 80 atm, the volatilization of As will be large and the stoichiometric composition will shift. It is effective to charge as much As as possible in advance to volatilize, but this is not a fundamental solution.

Therefore, in the present invention, this problem was solved by using Ga, As, and a GaAs compound as raw materials. At this time, although there is no particular limitation, it is preferable that the OaAs compound be 5
It is necessary to add ~90% by weight.

That is, the main feature is that the GaAs compound absorbs a portion of the reaction heat between Ga and As, thereby allowing the reaction to proceed slowly and reducing the volatilization of As. Furthermore, Ga A
Another major feature of the s compound is that it can reuse the GaAs residue from the liquid capsule method and the direct synthesis liquid capsule method.

A first embodiment of the present invention will be described with reference to FIG. Purity 99.9999 in Pyrolitenoch boron nitride crucible 7
% Ga300F, purity 99.9999% As32
1F and Pyrolyte Ink GaAs compound 379r (37,9% by weight) grown in advance in a boron nitride boat and 8203100 with a moisture content of less than 200 ppm
f and heated under argon gas pressure of 60°C, a molten BZ oa layer 3 covered the entire raw material at about 500°C. When the temperature was further increased to approximately 720° C., Ga and As reacted, and a portion of the GaAs compound was melted by the reaction heat. When the temperature is further increased to approximately 850°C, the reaction is almost complete, so the temperature is 20°C.
Ga As
A melt 2 was generated and the lower ends of the crystals were brought into contact with each other while pulling and growing. In this case, volatilization of As was extremely small, and the obtained crystal had no Ga precipitation due to compositional deviation, and a semiconductor crystal with an electrical resistivity of 10Ω, which was a particularly high value, was obtained.

(Second Example) Using the same apparatus as in FIG. 1, Ga50F with a purity of 99.9999% was placed in a crucible 7 made of quartz glass.
of As20Of, and 0aAs (60 mol of Ga, As4 (
1 mol) 6009 (approximately 546% by weight as pure GaAs), and B2031 with a water content of 200 ppm or less
Example 1 under argon gas pressurization of 60 atmospheres
Direct synthesis was performed in the same manner as above, and pulling growth was continued. As a result, the reaction was slow and the volatilization of As was small, the electrical resistivity of the obtained crystal was 5×10Ω, cfn, and no Ga precipitation was observed throughout the crystal.

As described in the above examples, this production method uses m-group raw material G
a, V group raw material As and ■-■ group compound raw material Ga A
By mixing and melting s and s, and by covering the surface with an inert substance B2O3 and allowing the accumulation layer to grow, it is possible to prevent the volatilization of raw materials and waste of resources, and to reduce the electrical resistivity. This has the effect that an excellent GaAs compound semiconductor crystal can be obtained.

Although the above embodiment describes the case of GaAs, it is also possible to use other m-group elements. For example, the present invention can be applied to all types of compound semiconductor crystals of the ■-■ group, including InP compound semiconductor crystals using In and P. Also, as a natural consequence, GaAs 1-zpχ,
Ternary mixed crystal systems such as Ga1-ztnzt' (0≦χ≦1) and Q81-χInχAs1-yPy (0≦χ,
It can also be applied to the direct synthesis liquid capsule pulling method for quaternary mixed crystal systems such as y≦1).

The method for manufacturing a ■-■ group compound semiconductor crystal of the present invention can effectively utilize compound residue with an excellent stoichiometric composition, and can also moderate the reaction and suppress volatilization of components. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a manufacturing apparatus that performs the pulling growth method.

Claims (1)

[Claims] 1. After heating the raw material contained in a crucible installed in a pressure vessel to produce a ■-■ group compound melt, the surface is covered with an inert melt and the above ■-■ group compound melt is heated. In the method for growing a crystal, the above-mentioned group ■-■ group compound melt is a molten mixture of a group ■ raw material, a group II raw material, and an m-v group compound raw material, and manufacturing of a ■-■ group compound semiconductor crystal. Method.