JPH09118596A - Production of compound semiconductor crystal, storing and transporting method of liquid gallium, and housing container of liquid gallium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply low-cost high purity gallium having excellent handling property for storage and transportation and to produce a III-V compd. semiconductor crystal of high purity. SOLUTION: Highly refined gallium is melted and housed in a container 2 to house liquid gallium and maintained at 0 to 80 deg.C. The container 2 for liquid gallium consists of a funnel-like 'Teflon (R)' resin container body 3 and a foamed polystyrene heat-insulating material 5 which surrounds the container body 3 and insulates and keeps the gallium 1 as a liquid state. After the liquid gallium 1 is housed in the container body 3, the space in the container body 3 is filled with nitrogen gas 6 and sealed. In this state, the gallium in a liquid state can be stored and transported and used as in a liquid state as the source material for a compd. semiconductor crystal without solidification to the final stage.

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 a compound semiconductor crystal, a liquid gallium storage / transportation method, and a liquid gallium storage container, and more particularly to GaAs, GaAlAs and Ga.
In the case of producing a compound semiconductor crystal using metallic gallium such as P as a raw material, the present invention relates to a technique of storing and transporting high-purity gallium in a liquid state and using it directly as a raw material of a compound semiconductor crystal.

[0002]

2. Description of the Related Art Compound semiconductor crystals containing a group III element, gallium, are used in light emitting diodes, laser diodes,
It is used in industrially important products such as field effect transistors and integrated circuits. For example, GaAs, GaAlAs,
A III-V compound semiconductor crystal such as GaP is a typical example.

Gallium is extracted as a by-product when refining aluminum from bauxite, and GaAs,
When used as a III-V group compound semiconductor crystal such as GaAlAs or GaP, a high-purity material having a purity of 99.9999% or more is used.

There are several kinds of purification methods, each of which requires complicated steps. Generally, purified and purified gallium is once melted, then divided into molds and solidified into pellets. The solidified pellets are
It is taken out of the mold and individually packaged in a plastic container or film for transportation. Since the melting point of gallium is 27 ° C., a cooling agent such as dry ice is used to prevent melting during transportation.

The pellets transported in this manner are II
When used as a group IV compound semiconductor crystal, it is taken out from a container or film, weighed, and then put into a crystal growth container to be used as a raw material for crystal growth.

[0006]

However, the conventional method for storing and transporting gallium in pellet form as described above has the following problems.

(1) The mold for pelletizing is expensive, and the pellet manufacturing cost is high. Therefore, the III-V group compound semiconductor crystal using this as a raw material is extremely expensive because the proportion of the raw material in the cost increases.

(2) Since it is divided into small pellets,
Packaging costs for individual packaging are required. Further, the pellets produced are easily broken, and it is necessary to carry the individually packaged items using a cushioning material. Therefore, the packaging cost is further increased, and the bulk is increased, so that the transportation cost is required.

(3) Pellets are weighed when used as a III-V group compound semiconductor crystal, but when measuring a fine weight, pellets of various weights are used just like the weight of a balance. You need to prepare. For this reason, the cost is increased and the weighing is complicated.

(4) Since what is once purified and melted in a large amount is solidified into small pellets, the surface area becomes large and surface oxidation easily occurs. Therefore, when it is used as a III-V group compound semiconductor crystal, so-called scum occurs and the yield and quality of the compound semiconductor product are reduced.

(5) Once purified, it is subdivided into individual pieces, and there is a possibility of contamination from the container and work atmosphere during the work, making it difficult to maintain high purity.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, to use gallium in a liquid state without solidifying it, and to manufacture a high-purity III-V compound semiconductor crystal at low cost. It is to provide a manufacturing method of. Another object of the present invention is to provide a liquid gallium storage / transportation method that is excellent in handleability and low in cost. Another object of the present invention is to provide a liquid gallium container capable of storing and transporting gallium in a liquid state with a simple structure.

[0013]

A method for producing a compound semiconductor crystal according to the present invention is a method for producing a compound semiconductor crystal using gallium as a raw material, wherein metallic gallium which has undergone the final purification step is melted and molten gallium is removed. It is kept warm and stored and transported in a liquid state, and when used as a raw material, gallium is directly weighed and placed in a crystal growth container in a liquid state without solidification. . Liquid gallium is GaAs or GaAl.
It is used for producing III-V group compound semiconductor crystals such as As and GaP.

The liquid gallium storage / transportation method of the present invention comprises melting metallic gallium, which has undergone the final purification step,
The molten gallium is stored and transported in a liquid state while keeping it warm. Note that the heat retention also includes heating. As a result, unlike the conventional ones, which are once solidified into pellets and stored and transported, no mold is required, there is no need to subdivide, and weighing is easy, so cost and purity are excellent and inexpensive. Compound semiconductor products can be manufactured.

The keeping temperature of liquid gallium during storage and transportation is preferably 0 ° C. or higher and 80 ° C. or lower. Although the melting point of liquid gallium is 27 ° C., once melted gallium does not easily solidify unless supercooled at a temperature lower than 0 ° C. Utilizing this property, the heat retention may be 0 ° C. or higher. On the other hand, 8
If the temperature exceeds 0 ° C, surface oxidation and reaction with the container are likely to occur rapidly. In order to prevent this, it is necessary to set the temperature not to exceed 80 ° C. Further, as compared with the case of solidifying into a small pellet, the purified metallic gallium is handled in a liquid state, the possibility of contamination is reduced, and the surface area is reduced, so that surface oxidation is less likely to occur. Therefore, when the stored and transported liquid gallium is used as a compound semiconductor crystal, scum does not occur and the yield and quality of the compound semiconductor product are improved.

A liquid gallium container is used to store and transport liquid gallium. The liquid gallium storage container of the present invention includes a container main body that stores liquid gallium, and a heat retaining unit that covers the periphery of the container main body and holds the liquid gallium in a liquid state.

In this case, the container body is preferably made of a material having low reactivity with liquid gallium, for example, a fluororesin such as Teflon (trade name) or an organic polymer material such as polypropylene, polyethylene or vinyl chloride. Further, the heat insulating means may be composed of a heat insulating material, a heating body, a vacuum heat insulating container or any combination thereof.

Here, as the heat insulating material, a material having a high heat insulating property such as styrofoam is used. As the heating body, for example, a heater wire and a temperature controller used for an electric blanket,
A self-controlling resistance wire heater or the like is used that applies resistance change with temperature. In addition, it is also effective to retain heat by utilizing the heat capacity of the contained items by utilizing the vacuum heat insulating layer. With these, a low cost heat insulation container can be realized. The provision of the discharge port at the bottom of the container body allows liquid gallium to be easily transferred to another container such as a crystal growth container. In addition, it is preferable that the inside of the container main body that constitutes the liquid gallium container is an atmosphere of an inert gas such as nitrogen or argon in order to prevent gallium oxidation.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method for producing a compound semiconductor crystal, a liquid gallium storage / transportation method, and a liquid gallium storage container according to the present invention will be described below with reference to the drawings.

First Embodiment Metallic gallium purified to a purity of 99.9999% or more is heated to 80 ° C. and melted, and 200 kg of melted liquid gallium is contained in the liquid gallium container 2 shown in FIG. .
The liquid gallium container 2 is a funnel-shaped container body 3 made of Teflon resin for containing the liquid gallium 1, and a styrofoam insulation that covers the circumference of the container body 3 and adiabatically holds the liquid gallium 1 in a liquid state. And a material 5. The heat insulating material 5 includes a lid portion 5a that covers the opening of the container body 3,
It is composed of a box portion 5b that covers the side surface portion and the bottom portion of the container body 3. A discharge port 4 formed of a cock for discharging the liquid gallium 1 is attached to the bottom of the container body 3. After accommodating the liquid gallium 1 in the container body 3, the space inside the container body 3 was sealed with nitrogen gas 6.

This liquid gallium container 2 is filled with GaAlA.
The s compound semiconductor crystal was transported to the site of the liquid phase epitaxial growth process, the outlet 4 was opened, and 2050 g was weighed on a graphite jig (not shown) for crystal growth. 12 from storage in liquid gallium storage container 2 to storage
It has been 0 hours. The temperature of gallium was about 25 ° C., which was slightly higher than the room temperature of 22 ° C., and the state of liquid was maintained.

Conventionally, in the case of 2050 g, 20 pellets of 100 g and one pellet of 50 g are weighed, but in the present embodiment, the weighing can be completed once with the graphite jig. An oxide film usually floats on the surface of the gallium residual solution that has been epitaxially grown, but this was not recognized in the present embodiment. The quality of the obtained crystals was no different from the conventional one.

Second Embodiment The liquid gallium container 11 shown in FIG. 2 was used. The liquid gallium container 11 has basically the same configuration as that of the first embodiment. However, the heater 8 used as an electric blanket was arranged in the outer container 7 which covered the container body 3. The space inside the container body 3 was sealed with argon gas 9. Liquefaction of liquid gallium 1 is performed at 40 ° C and 40 ° C with the heater 8.
Continued to heat and stored.

This liquid gallium container 11 is filled with GaAl.
The As compound semiconductor crystal was transported to the liquid phase epitaxial growth process site and weighed 2050 g on a graphite jig for growth. It has been 240 hours from the time of being stored in the liquid gallium container 11 until the weighing. The temperature of gallium was maintained at about 40 ° C.

The floating of the oxide film on the surface of the gallium residual solution epitaxially grown and the quality of the obtained crystal were as good as those in the first embodiment.

Third Embodiment The liquid gallium container 12 shown in FIG. 3 was used. The liquid gallium container 12 basically has the same configuration as that of the first embodiment. However, a vacuum heat insulating container 10 made of stainless steel was arranged around the container body 3. Liquefaction of liquid gallium 1 was performed at 70 ° C.

This liquid gallium container 12 is filled with GaAl.
Liquid compound epitaxial growth process of As compound semiconductor crystals is transported to the site, and 2050 g is added to the graphite jig for growth.
Weighed. It has been 240 hours from the time of storage in the liquid gallium storage container 12 to the weighing including storage. The temperature of gallium was maintained at about 30 ° C.

The floating of the oxide film on the surface of the gallium residual solution epitaxially grown and the quality of the obtained crystal were as good as those in the first embodiment.

Fourth Embodiment Under the same conditions as in the first embodiment, the ambient temperature is about 0.degree.
When left for a while, the temperature of gallium became almost 0 ° C., but the fluidity of the liquid could be maintained during use. However, in order to prevent the possibility of solidification in the growth jig, the graphite jig was preheated to 30 ° C. before use.
The results were good.

Other Embodiments Similar results were obtained by using polypropylene, polyethylene or vinyl chloride for the container body. Also, GaAs
It was also used well for melt growth of GaP and liquid phase epitaxial growth. Further, when the heat insulating material 5 of the first embodiment, the heater 8 of the second embodiment, and the heat insulating means of the vacuum heat insulating container 10 of the third embodiment are arranged around the container body 3 in an arbitrary combination, the result is good. Good heat retention was obtained.

Effects of the Embodiments From the above-described embodiments, it has been found that by storing and transporting the metal gallium, which has undergone the final process, in a liquid state, the cost is low and the purity is excellent. It was also found that handling liquid gallium instead of pellets greatly improves the gallium container, storage, and transportation method. Further, gallium can be weighed together with the crystal growth jig, so that weighing is extremely easy.

[0032]

According to the present invention, since gallium is used in a liquid state without solidification, the handling and weighing costs in the semiconductor crystal manufacturing process can be greatly reduced. In addition, since gallium, which has undergone the final purification step, is handled in a liquid state as it is, valuable resources can be effectively utilized, and the compound semiconductor crystal can be economically produced by effectively utilizing the maximum purity.

According to the present invention, since gallium is stored and transported in a liquid state as it is, it is easy to handle, is low in cost, and is oxidized by forming it into pellets as in the prior art, or a container for subdivision / packaging. It is possible to effectively prevent contamination from the.

Further, according to the present invention, gallium can be easily stored and transported in a liquid state with a simple structure consisting of the container body and the heat retaining means.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid gallium container for explaining the first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a liquid gallium container for explaining the second embodiment.

FIG. 3 is a sectional view of a liquid gallium container for explaining the third embodiment.

[Explanation of symbols]

 1 Liquid Gallium 2 Liquid Gallium Storage Container 3 Container Body 4 Discharge Port 5 Heat Insulating Material 6 Nitrogen Gas 8 Heater (Heating Body) 9 Argon Gas 10 Vacuum Insulated Container

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Claims (9)

[Claims] 1. In a method for producing a compound semiconductor crystal using gallium as a raw material, metallic gallium that has undergone the final purification step is melted, and the molten gallium is kept warm and stored / transported in a liquid state. A method for producing a compound semiconductor crystal, characterized in that the compound semiconductor crystal is used as it is in a liquid state. 2. A method for storing and transporting liquid gallium, in which metallic gallium that has undergone the final purification step is melted and the molten gallium is kept warm and stored and transported in a liquid state. 3. The method for storing and transporting liquid gallium according to claim 2, wherein the heat retention temperature is 0 ° C. or higher and 80 ° C. or lower. 4. A liquid gallium storage container comprising a container main body for storing liquid gallium, and a heat retaining means for covering the periphery of the container main body and holding the liquid gallium in a liquid state. 5. The liquid gallium container according to claim 4, wherein the container body is made of a material having low reactivity with liquid gallium. 6. The liquid gallium container according to claim 5, wherein the material of the container body is a fluororesin such as Teflon, or an organic polymer material such as polypropylene, polyethylene or vinyl chloride. 7. The liquid gallium storage container according to claim 4, wherein the heat insulating means is a heat insulating material, a heating body, a vacuum heat insulating container, or any combination thereof. 8. The liquid gallium storage container according to claim 4, wherein a discharge port is provided at the bottom of the container body. 9. The liquid gallium storage container according to claim 4, wherein the inside of the container main body constituting the liquid gallium storage container is an inert gas atmosphere.