JPS6140898A - Process for preparing single crystal - Google Patents

Abstract

PURPOSE:To reduce generation of dislocation of thermal stress and to grow a long-sized single crystal in the prepn. of a single crystal by the pulling method by evaporating GaAs contained in a specified jig and retarding vaporization and isolation of the component at the surface of a pulled up single crystal. CONSTITUTION:GaAs melt 5 in a crucible 6 revolved by a revolving driving shaft 2 is heated by a heater 7, and the melt is sealed with a liquid sealing agent (B2O3) layer 4. On one hand, GaAs 9 contained in a jig 10 for placing GaAs supported by a heat shielding material 8 in a high temp. section in the crucible 6 is decomposed slowly to generate As vapor, and to deposit Ga in a inside bottom of the jig 10. A single crystal 3 is grown by pulling up a single crystal and revolving with a revolving shaft for the crystal while retarding evaporation of As on the surface of the pulled up single crystal and deposition of Ga. After completion of the crystal growth, the single crystal is cooled, thus, generation of dislocation of thermal stress is reduced remarkably and a long-sized single crystal contg. less crystal defect is obtd.

Description

[Detailed description of the invention] [Background and purpose of the invention] The present invention relates to improvements in single crystal manufacturing methods.

A conventional single crystal manufacturing method using the LEC method will be explained with reference to FIG. FIG. 3 is a longitudinal cross-sectional view, and 1 is a crystal rotation drive shaft;
2 is a crucible rotation drive shaft that rotationally drives the crucible 6; 3 is a pulled single crystal grown on the lower end of the crystal rotation drive shaft 1; 4 is Ga
This is a liquid sealant for the B2O3 layer that seals the liquid surface of the raw material liquid 4 of the As solution.

7 is a heater, and 8 is a heat shielding agent.

Then, the GaAs melt is heated by the heater 7 in the rotatably driven crucible 6 and covered with an 8203 layer, and the atmospheric pressure is raised to <L to prevent the evaporation of As and grow while being rotatably driven by the crystal rotation drive shaft 1. The pulled single crystal 3 is pulled. In this case, when the pulled single crystal 3 comes out from the surface of the liquid sealant 4 of 8203, As gradually evaporates from the surface of the single crystal, and an excess of Ga exists on the surface. Crystal defects occur. If a large amount of Ga is precipitated, it may flow down the crystal surface to the crystal growth interface and hinder single crystal growth.

For this reason, efforts are generally made to lower the temperature of the single crystal produced from B2O3 to reduce the volatilization of As, and a hot zone in the temperature distribution is used to facilitate cooling of the pulled single crystal. This increases the thermal stress applied to the pulled single crystal, making it difficult to produce long single crystals with few crystal defects using the conventional LEC method.

The present invention has been made in view of the above situation, and allows the growth of long single crystals with low defects.

The purpose of this invention is to provide a method for producing a single crystal.

[Summary of the Invention] In the method for producing a single crystal of the present invention, a raw material liquid is contained in a crucible that is heated from the side periphery and from below by a heater, and a liquid sealant is applied to the crucible so as to seal the liquid surface of the raw material liquid. A component that suppresses volatilization and release of components on the surface of the pulled single crystal when manufacturing a single crystal grown through a crystal rotation drive shaft filled in a crucible and inserted through the liquid sealant. A jig filled with a substance consisting of is placed in the high temperature part of the crucible,
This is a method of evaporating the substance in the jig to suppress volatilization and release of components on the surface of the pulled single crystal.6 For example, when the raw material liquid is GaAs, the inside of the pulling device is filled with As or p-
The above objective can be achieved by creating an atmosphere containing vapor such as sb. However, even if these vapors can be supplied temporarily, the atmosphere containing these vapors cannot be maintained for a long period of time because the inner wall of the device is made of low-temperature water-cooled stainless steel and will precipitate there. Therefore, in the present invention, a compound such as GaAs is used to maintain a vapor partial pressure that continuously suppresses the decomposition of the single crystal by utilizing the phenomenon that these compounds gradually decompose.

EXAMPLE] The method for producing a single crystal of the present invention will be described below using examples with reference to FIG. 1, in which the same parts as in the prior art are denoted by the same reference numerals and the explanation of the structure of the same parts will be omitted. FIG. 1 is a longitudinal sectional view. In the figure, 9 is GaAs, and a heat conductive material 8 is placed in the high temperature part of the crucible 6.
It is housed in a GaAs mounting jig 10 which is supported and disposed in the GaAs mounting jig 10.

While the pulled single crystal 3 is growing and pulling continues, the material GaAs in the jig 10 gradually decomposes and becomes As.
Steam is generated and Ga is deposited on the inner bottom of the GaAs mounting jig 10. This suppresses the volatilization of As and the precipitation of Qa on the surface of the pulled single crystal 3, so that a long single crystal can be easily grown.

In addition, in the conventional LEC method, it is necessary to quickly cool the pulled single crystal 3 in order to suppress the volatilization of ΔS.
Although high-density thermal stress dislocations occurred, in this example, this restriction is removed, it becomes possible to slowly cool the pulled single crystal 3, and low dislocations can also be achieved.

Then, during GaAs single crystal growth, GaA is placed in the jig 10.
When using s9, the jig 10 should be placed at a position that is higher than the temperature of the surface of the growing single crystal that is in contact with the atmospheric gas and is close to the growing single crystal, such as the inner peripheral edge of the crucible 6. do. The temperature is not such a high vortex that it completely decomposes the single crystal during pulling, but is usually in the range of several tens of degrees higher than the crystal surface temperature. Other InSb, GaP, 1
When np or the like is used, a temperature as high as possible is selected from the relationship between temperature and dissociation pressure within a range that does not completely dissociate during the pulling process, as described above.

In this way, in the single crystal manufacturing method of this example, Ga
Volatilization of As from the surface of a pulled As single crystal.

Since GaAs, which suppresses the release of Ga, is placed in a high-temperature part of the crucible and evaporated, As on the surface of the pulled single crystal is
By suppressing the volatilization of As and the liberation of Ga, and by suppressing the generation of crystal defects caused by the volatilization of As and the liberation of Ga, a long single crystal with low defects can be grown. Furthermore, it is no longer necessary to rapidly cool the pulled single crystal, and it becomes possible to keep it warm or heat it afterward, thereby significantly reducing the occurrence of thermal stress dislocations.

Also, instead of GaAs as the material installed in the jig,
Compound moieties such as p and sb can be used; in this case, the volatilization of As cannot be suppressed, but the same effect can be obtained by preventing the release of Ga. Furthermore, as a method of placing the compound for vapor supply in the apparatus, a hot zone for housing and heating the compound may be provided in the same position as the hot zone for crystal growth.

FIG. 3 shows another embodiment, and the difference from the above embodiment is that in the above embodiment, a jig 10 containing GaAs is fixed to a heat shield material 8, whereas in this embodiment, a crucible 6 is fixed. The present invention has the same function and effect as the above embodiment.

Further, each of the above embodiments has been described as an example applied to the production of a GaAs single crystal, but 1n3b.

The same applies to the case of growing a single crystal product of a compound such as GaP or InP in which one of the components is an external volatile substance.

[Effects of the Invention] As described above, the method for producing a single crystal of the present invention has the effect of allowing elongated single crystals with low defects to be grown.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the current single crystal manufacturing equipment, Figures 2 and 3
Each figure is a sectional view of an apparatus for implementing the single crystal manufacturing method of the present invention. 1... Crystal rotation drive shaft, 3... Pulled single crystal, 4...
・Liquid sealant, 5... Raw material liquid, 6... Crucible, 7.
··motor.

Claims (2)

[Claims] (1) A raw material liquid is stored in a crucible that is heated by a heater from the side periphery and from below, and a liquid sealant is filled in the crucible so as to seal the surface of the raw material liquid, and the liquid sealant is In a method of pulling and manufacturing a single crystal grown through a crystal rotation driving shaft inserted through a A method for producing a single crystal, characterized in that the jig is placed in a high-temperature part of the jig, and the substance in the jig is evaporated to suppress volatilization and release of components on the surface of the pulled single crystal. (2) The single crystal according to claim 1, wherein the raw material liquid is GaAs, and the substance contained in the jig is a substance containing an As compound or a component that reacts with Ga to form a high melting point compound. Production method.