JPH0825824B2 - Inorganic article for crystal growth - Google Patents

Description

TECHNICAL FIELD The present invention relates to an inorganic article used for crystal growth of a compound semiconductor, and more particularly to a carbon boat, a container (crucible, etc.) used for liquid phase growth, The present invention relates to a crystal-growing inorganic article in which an amorphous carbon coating is applied to the entire surface of a porous inorganic article such as a lid.

[Conventional technology]

There are various kinds of porous (innumerable micropores existent) inorganic articles used for the crystal growth technology of compound semiconductors, but carbon boats (graphite boats), containers (crucibles, etc.) are target articles that require airtightness. ), Container lids, etc., which are usually made of graphite.

Among them, for example, a carbon boat is often used in a slide boat method adopted in liquid phase epitaxy which is an epitaxial crystal technique.

As is well known, liquid phase epitaxy involves converting a low melting point metal into a liquid, using it as a solvent to dissolve a semiconductor raw material to be grown at a high temperature, and cooling the solution to reduce the saturation. Epitaxy is based on the fact that semiconductors are deposited on a substrate.

[Problems to be Solved by the Invention]

By the way, since graphite is generally porous, as shown in FIGS. 2 and 3, such a graphite boat 20 has a porosity of 1% or more even if it is a non-defective product, and has a small groove (or recess) 30 or There are innumerable holes (or pinholes penetrating the boat) 31 reaching the deep part of the boat, and the surface of the boat 20 has a surface in which these recesses are scattered.

When such a boat 20 is used for liquid phase epitaxy as it is, that is, as shown in FIG. 2, the substrate 10 is arranged above the boat 20, and the space between the substrate 10 and the boat 20 is filled with the solution 12.
When growing the epitaxial crystal 14 on the substrate 10, the solution 12 intrudes into the recesses 30, 31 on the surface of the boat 20, and when the solution 12 is gradually cooled in this state, the crystal 16 having the recess as a crystal nucleus is centered on the recess. Precipitates on the boat surface. As a result, epitaxial growth on the substrate 10 facing the crystal 16 is hindered, the crystal layer portion becomes a thin film, and the obtained epitaxial layer 14
Surface becomes uneven, and a crystal layer having a uniform film thickness cannot be obtained.

Further, when the solution is replaced after the growth is completed, the crystal 16 precipitated on the boat surface is lost and adheres to the epitaxial layer 14 on the substrate 10, so that a good quality crystal cannot be obtained.

Further, the boat 20 has a property of lacking airtightness due to the innumerable recesses 30 and 31 (especially the through holes 31). Liquid phase epitaxy involves using epitaxial growth solutions at high temperatures (500-110
The solution is heated to about 0 ° C) and then cooled, but the solution also contains volatile elements having a high vapor pressure, such as arsenic and phosphorus. easy. In such cases, the stoichiometric composition of the growth solution is often deviated, which often causes structural defects in the crystal. This problem becomes more serious as the epitaxial growth is performed at a higher temperature for a longer time.

The problem of the porosity as described above is that it is applicable not only to carbon boats but also to general porous inorganic articles such as graphite containers (crucibles, etc.) and container lids.

Therefore, in view of the above points, an object of the present invention is to provide a novel inorganic inorganic material for crystal growth capable of solving the above-mentioned various problems found in the porous material in the porous inorganic material used for the crystal growth of the compound semiconductor. To provide.

[Means for solving the problem]

The purpose is to coat an amorphous carbon obtained by using a carbon material gas as a raw material on the entire surface of a porous inorganic article used for crystal growth, or an amorphous carbon obtained by ion beam sputtering with a carbon target. Or an amorphous carbon coating obtained by laser deposition using solid phase carbon as a raw material.

That is, in the inorganic article of the present invention, the entire surface of the porous inorganic article is coated with the amorphous carbon obtained by the method as described above, so that the recesses such as minute grooves and holes of the inorganic article are sealed. At the same time the surface becomes flat,
There are no crystal nuclei during epitaxial growth, and no crystal precipitation occurs on the article surface. As a result, an epitaxial layer having a uniform film thickness is obtained, and deposition crystals are not attached to the epitaxial layer. In addition, the vaporizable element in the growth solution is not scattered from the concave portion to the outside of the article, and the airtightness is sufficient.

The porous inorganic article as referred to in the present invention refers to any porous article used for crystal growth of a compound semiconductor, and in addition to the above graphite, ceramic (h-BN, Al ₂ O).
₃ ) etc. are also included.

The method for coating the surface of the porous inorganic article with the above-mentioned amorphous carbon includes the following methods. For example, hydrocarbon gas (methane, acetylene, propane, butane, etc.), ketones (acetone, etc.), alcohols (methanol, ethanol, etc.), aromatic hydrocarbons (benzene, toluene, etc.) are used as the carbon material gas. Then, the amorphous carbon is coated by plasma CVD or ordinary pyrolysis CVD. Other methods such as ion beam sputtering using carbon as a target, laser deposition, and the like can also be used for coating.

The coating film thickness may be such a thickness that can seal the recesses and flatten the surface. In practice, it varies depending on the use and size of the article, but for articles such as carbon boats, it is 1 to 30 μm, preferably 2 μm. ~ 10μm, especially 5μm
The degree is preferred.

〔Example〕

Hereinafter, the inorganic article for crystal growth of the present invention will be described, and a carbon boat will be taken as a typical example thereof. Since the shape and structure of the carbon boat itself may be a usual mode, the same parts as those in FIGS. 2 and 3 showing the liquid phase epitaxy using the conventional carbon boat are designated by the same reference numerals.

As is apparent from FIG. 1, the surface of a normal graphite carbon boat 20 is provided with a uniform coating 1 of amorphous carbon obtained by the above-described method of the present invention and is present on the boat 20. Countless micro grooves 30 and holes
31 is sealed by coating 1 and the boat surface is flat.

When liquid phase epitaxy is performed using such a boat 20, there is no crystal nucleus on the surface of the boat 20, so that the epitaxial layer 4 having a uniform thickness grows on the substrate 10.

In addition, since the through hole 31 is particularly closed, a vaporizable element having a high vapor pressure will not be scattered outside the boat through the through hole 31 during the epitaxial growth.

〔The invention's effect〕

As described above, the crystal-growing inorganic article of the present invention is
Since the entire surface of the porous inorganic article is coated with amorphous carbon, the microscopic grooves and pores of the article are sealed and the article surface becomes flat, and the following effects i to v are achieved.

i) An epitaxial crystal having a uniform film thickness is obtained, and the surface of the crystal layer is flat and mirror-finished.

ii) Impurities such as graphite, which is the material of the article, are not mixed in the epitaxial crystal.

iii) After the growth is completed, the solution can be completely removed from the substrate without the impurities adhering to the epitaxial layer.

iv) The epitaxial efficiency on the substrate is improved, and the semiconductor material can be used without waste.

v) During liquid phase epitaxy, the fugitive element in the epitaxial growth solution will not be scattered outside the micropores existing in the article itself.

Therefore, with the crystal-growing inorganic article of the present invention, it is possible to efficiently grow a high-quality crystal with few structural defects, except for a solution system that reacts with carbon, particularly III-
Examples of group V semiconductors include GaAs, AlGaAs, InP, GaInP,
Examples of II-VI group semiconductors such as InAs include ZnS, ZnSe, and S.
It is effective in liquid phase epitaxial growth of nTe.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an inorganic article of the present invention and liquid phase epitaxy using the article, and FIGS. 2 and 3 show conventional inorganic articles and liquid phase epitaxy using the article. It is sectional drawing at the time of going. 1: Coating of amorphous carbon obtained by the method disclosed in the present invention 4: Epitaxial growth layer 10: Substrate 12: Growth solution 20: Graphite carbon boat 30, 31: Recesses (grooves, holes)

Claims (1)

[Claims] 1. An amorphous carbon obtained by coating an amorphous carbon obtained by using a carbon material gas as a raw material or an ion beam sputtering targeting carbon on the entire surface of a porous inorganic article used for crystal growth. An inorganic article for crystal growth, characterized in that it is provided with a coating of high-quality carbon or a coating of amorphous carbon obtained by laser deposition using solid-phase carbon as a raw material.