JPS58145691A - Production of single crystal - Google Patents

Abstract

PURPOSE:A means is set to control the partial pressure of volatile components in the raw materials for single crystal in the space between the inert melt covering the melted raw materials and the inert melt seal at the top, thus producing single crystals of highly decomposable compound having high accuracy of stoichiometric composition. CONSTITUTION:After the inside of the pressure vessel 1 is evacuated, a male- female type cap 6 is fitted on the top of the crucible 2 in the state that the pulling-up shaft 12 penetrates through the cap 6, then the B2O3 7 in the cap is melted with heater 8 to effect sealing. An inert gas is introduced into the vessel 1 and the arsenic 9 in the subcrucible 10 is heated with heater 11 to form its vapor. Thus, the inside of the crucible is filled with the vapor of arsenic and simultaneously, GaAs is heated with the heater 5 to form its melt 4 covered with B2O3 melt 15. At this time, the vapor pressure of arsenic is made controllable by the temperature of the crusible 10. Then, the seed crystal 13 is brought into contact with the melt 15 and pulled up while rotating to produce the single crystal of GaAs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for producing a single crystal of a compound having a high decomposition pressure.

[Prior art and its problems]

A liquid force pull-up method is known as a method for producing high decomposition pressure compound crystals such as GaAs, GaP, and ZnP. In this method, the surface of the raw material melt of the compound is
This method involves covering the single crystal with an inert liquid such as, and then pulling the single crystal upward while applying Calo pressure from above with an inert gas that is higher than the decomposition pressure of the compound. By the way, in this method, the single crystal pulled above the inert liquid coating is exposed to the inert gas atmosphere at a high crystal density, so that volatile components are likely to dissociate from the surface of the single crystal. For this reason, the grown crystal deviates from the chemical ψ theoretical composition, and especially near the surface of the single crystal, there is no
It contains many defects such as, and the crystallinity is inhibited.

In addition, non-volatile components remain as precipitates, which cause the generation of twins and polycrystals, resulting in an extremely low F single crystallinity. In order to solve these problems, Japanese Patent Application Laid-Open No. 123585/1985 discloses an oxidized boron melt in which a high decomposition pressure compound melt is formed at the upper end of the crucible to form a single crystal in the crucible. When the oxidation of the pool constituting the double melt tube in conjunction with the nol is coated with the borium melt, only the volatile components in the high decomposition pressure compound melt are oxidized and selectively coated with the boron melt (i- As a result, an atmosphere of volatile components is formed between the boron oxide melt coating and the boron oxide melt seal, and the volatile components are removed from the surface of the growing single crystal. It is remembered that the crystallinity near the surface of the single crystal is less likely to be inhibited. However, even with this method, the vapor pressure of the volatile component atmosphere on the boron melt coating is lowered by the oxidation from the high decomposition pressure compound melt. Steaming through boron melt coating
:There is a problem that it cannot be controlled with good reproducibility because it depends on the amount.

[Purpose of the invention]

Based on the above-mentioned viewpoints, the present invention provides a method for producing a single crystal of a high decomposition pressure compound with good crystallinity with good reproducibility by controlling the stoichiometric composition.

[Summary of the invention]

In order to achieve the above object, the present invention covers the upper end of a crucible holding a raw material melt coated with an inert melt inside with an inert melt, and the inert melt in the crucible. An auxiliary crucible for holding volatile component elements of the raw material melt is provided in the space between the melt coating and the inert melt channel, and by controlling the temperature of the auxiliary crucible, the volatile components in the space are This is a method of manufacturing single crystals by controlling vapor pressure.

[Effects of the invention] The present invention provides high decomposition compounds and the pulling of snout single crystals.
Since the single crystal is manufactured by controlling the vapor pressure of the volatile components on the inert melt coating, the volatile components do not dissociate from the surface of the growing single crystal and the crystallinity near the surface of the single crystal is not inhibited. In addition to making it possible to manufacture high-quality single crystals, the generation of twins and polycrystals can be suppressed, and the single crystallization rate can also be improved.

[Embodiments of the invention]

Hereinafter, the present invention will be applied to B2 as an inert melt coating and/or material.
A description will be given based on an example in which a GaAs single crystal is produced using O3. When producing this GaAs single crystal, a manufacturing apparatus as shown in the figure is used. A fitting lid 6 containing 82037 which is heated by the heater 8 and becomes a melt.
At the same time, a rotating pulling shaft 12 with a seed crystal 13 attached to the tip and an auxiliary crucible 10 containing arsenic 9 heated by a heater 11 to give a desired vapor pressure are attached. B2O to be received &15
3 and a crucible 2 containing a GaAs raw material to become a GaAs melt 4 and supported by a susceptor 3 are hermetically installed in a pressure vessel 1. After the inside of the pressure vessel 1 is evacuated to create a vacuum, the fitting lid 6 is fitted into the north end of the crucible 2 with the lifting shaft 12 pushed through, and then the 8 in the fitting lid 6 is inserted.
The upper end of the crucible 2 is cooled by heating 2037 with the heater 8 to form a melt, and an inert gas such as nitrogen is introduced into the pressure vessel 1. . Next, the arsenic 9 in the auxiliary crucible 10 is heated by the heater 11 to generate arsenic vapor,
The inside of the crucible 2 is made into a hydrogen atmosphere, and the crucible 2
The B2O3 and GaAs raw materials inside are heated by a heater 5 to form a GaAs melt 4 covered with a B2O3 melt 15. At this time, the temperature of the wall of crucible 2 is always the same as that of auxiliary crucible 1.
The temperature of the auxiliary crucible 10 is set to be higher than the hood i of 0, so that the atmospheric pressure inside the crucible 2 can be controlled by the temperature of the auxiliary crucible 10. Next, the seed crystal 13 is passed through the B2O3 melt 15 to G
A GaAs single crystal is produced by bringing it into contact with the aAs melt 4 and pulling it upward while rotating it.

In the GaAs single crystal obtained by such a method, no evaporation of arsenic was observed from the crystal surface. In addition, there is almost no difference in the etch pit density between the center and the periphery, and the overall etch pit density is on the order of 103cIrL-2, which is reduced to i/10 of the conventional pulled crystal, and deep levels due to defects are also detected. It became clear that the quality of the grown crystals was significantly improved. In addition, the occurrence of twins and polycrystals has been significantly reduced, and the single crystallization rate has been significantly improved from 60% to 90%.

In addition, in the detailed explanation of the present invention, GaAs
The explanation was given using single crystal pulling as an example, but OaP and In
Of course, the present invention can be applied to any other method for pulling crystals of high decomposition pressure compounds such as P.

[Brief explanation of drawings]

The drawing is a cross-sectional view of a preliminary manufacturing apparatus for explaining the single crystal manufacturing method of the present invention. In the figure, l is a high-pressure container, 2 is a crucible, 3 is a susceptor, 4 is a GaAs melt, 5 is a heater, 6 is a fitting lid, 7
is B2O3 for sole, 8 is heater for seal, 9 is arsenic,
10 is an auxiliary crucible, 11 is an atmosphere control heater, 12 is a rotational pulling shaft, 13 is a seed crystal, 14 is a GaAs single crystal,
(2) 5 is a B2O3 melt.

Claims (4)

[Claims] (1) Seal the end with an inert melt in a pressure chamber with an inert gas, and combine with the inert melt inside.
A crucible holding a high-decomposition-pressure compound melt coated with an inert melt forming a heavy melt seal is provided, and a pulling shaft with a seed crystal attached to the tip is inserted into the crucible to hold the inert melt. passing through the melt seal and the inert melt coating;
When a seed crystal is brought into contact with the high decomposition pressure compound melt and the seed crystal is pulled up to produce a single crystal, the high decomposition pressure between the inert melt seal and the inert inert melt coating is having means for controlling the vapor pressure of volatile components of the compound;
A method for producing a single crystal, characterized in that the vapor pressure of the volatile component is controlled by the vapor pressure control means. (2) As a means for controlling the vapor pressure of the volatile components of the high decomposition pressure compound, an auxiliary crucible holding the volatile component elements of the high decomposition pressure compound is provided in the crucible, and the temperature of the wall of the crucible is controlled by the auxiliary crucible. In addition to keeping the temperature at a temperature that is better than that of
A method for producing a patented crystal, characterized in that the vapor pressure of the volatile component is controlled by the temperature rL of the auxiliary crucible. (3) The method for producing a single crystal according to claim 1, wherein the high decomposition pressure compound is a compound semiconductor. (4) Compound semiconductors are daAs, GaP, fnP
A method for producing a single crystal according to claim 3, wherein the single crystal is torn.