RU2552463C1 - Method of fuse securing during growth of monocrystals by method of direct crystallisation from melt in horizontal glass vacuum-treated container - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: for fuse securing in horizontal glass vacuum-treated container the major part of fuse is melted from side opposite to the seed melting place, and melt is crystallised in contact with the container walls.

EFFECT: yield of high quality mono-oriented crystal increases due to increased reliability of the fuse mechanical securing and improved its thermal contact with the container walls.

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Description

The invention relates to a technology for producing single crystals of semiconductor and metallic materials and can be used to obtain single crystals with growth anisotropy from a melt of the type bismuth and its antimony alloys, including by the method of zone recrystallization.

The purpose of the invention is to increase the output of a mono-oriented crystal of high quality during directed crystallization from seed in a horizontal long-dimensional evacuated glass container by increasing the reliability of the mechanical fastening of the seed and improving its thermal contact with the walls of the container, which is necessary to ensure sufficient and stable outflow of heat generated at the crystallization front .

A known method of growing (obtaining) optical single crystals of germanium, patent RU 2261295 (published 2005.09.27), in which the crystal is grown from the melt from the fixed seed according to the Czochralski method in vacuum, followed by annealing without excavating the crystal from the growing unit.

A known method of growing (obtaining) silicon crystals, patent RU 2278912 (published 2006.06.27), also by the Czochralski method with a rotating crucible and seed with different speeds in an inert gas environment. These descriptions do not specify the method of attaching the seed and the method of removing latent heat of crystallization from the crystallization front.

In contrast to our proposed method, both of these methods are designed for high-temperature (above 1000 K) crystallization and require complex and expensive equipment with a complex control system for thermal conditions by varying the modes of heating furnaces and the modes of heat removal from the seed (in the method RU 2261295) using water coolant.

The inventions RU 2199614 (published on 02.27.2003) and RU 2199615 (published on 02.27.2003) are devoted to a method and apparatus for growing crystals from the seed in the upward direction in a graphite cylindrical container, which is also a socket for attaching the seed. In this case, in either case, it is stipulated that the seed in the container is placed without a gap between the walls, i.e. the seed, in contrast to the method proposed by us, must be pre-processed in some way in order to have a section strictly coinciding with the section of the inner cavity of the container (crucible), which is not always possible without damaging the structure. The environment in which the process proceeds is not specified in these inventions either.

The closest to the claimed method is the method of growing crystals from a cooled seed by the method of horizontal zone melting in an evacuated glass container, described by the author of this application in the article (Bochegov V.I., Ivanov K.G., Rodionov N.A. Single crystal growth bismuth-antimony from a cooled seed // Instruments and experimental technique, 1980, No. 2, p. 218). This technique has been used by the author for many years to obtain single crystals. However, the percentage of yield of mono-oriented crystals and their quality is significantly improved with the use of the proposed method of attaching seeds, because the temperature field near the crystallization front in this case became much more stable.

Example. Test method for growing single crystals of bismuth alloys with antimony. Into a half-loaded material, a horizontal container made of glass of the type “ZS-5 or Pyrex” with a length of 150-200 mm, an internal diameter of 15-18 mm, a wall thickness of 1.5-2 mm, having a drawn shank for seed with an inner diameter of 6-8 mm, a glass thickness of 0.8-1.2 mm, the seed is placed close to the grown material of the corresponding cross section and crystallographically perfect from the etched side with a length of 30-60 mm. After this, the ampoule is pumped out and sealed under vacuum. A heater is placed on the shank in the region of the molten portion of the seed and the portion of the seed is melted. Monitoring the volume of the molten seed portion is carried out visually. About 3 / 4-4 / 5 of the seed length is melted. Immediately after the molten part of the seed takes the shape of the bottom of the inner surface of the ampoule shank, the heater is turned off, and the melt crystallizes. Leakage of the melt under the solid part of the seed and spreading into the free part of the shank at the indicated seed sizes and the diameter of the ampoule shank does not occur due to the surface tension of the melt. Next, a radiator is mounted on the shank and the ampoule is installed in the device for zone recrystallization.

The proposed method allows a relatively simple and reliable fixation of the seed inside the evacuated container and provides good thermal contact with the radiator hung on the container in the seed region, which in turn ensures the stability of the heat outflow along the crystallization line of the material and allows to increase the output of single-crystal ingots by the method of horizontal recrystallization to almost 100 %

Claims (1)

A method of attaching a seed when growing single crystals by directional crystallization from a melt in a horizontal glass evacuated container, characterized in that the majority of the seed is melted from the side opposite to the location of the seed, and the melt is crystallized in contact with the walls of the container.