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Crystal growth method in crucible with step portion

  • US 4,946,542 A
  • Filed: 12/05/1988
  • Issued: 08/07/1990
  • Est. Priority Date: 12/05/1988
  • Status: Expired due to Term
First Claim
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1. A process for making large single crystals of a semiconductor material comprising the steps of:

  • introducing into the bottom part of a crucible a relatively small monocrystalline seed crystal of the material;

    introducing over the seed crystal a quantity of raw material from which the single crystal may be made and an encapsulant material;

    heating the crucible to melt the raw material, the encapsulant material, and part of the seed crystal;

    the molten encapsulant material having a lower density than the molten semiconductor material so as to float on the molten semiconductor material; and

    freezing the semiconductor material such that it extends as substantially a single crystal from the seed crystal, wherein;

    the inner surface of the crucible has a larger periphery portion and a smaller periphery portion defining therebetween a step portion extending around the periphery of the inner surface of the crucible;

    at least part of the larger periphery portion is located between the molten encapsulation material, as it is supported on the frozen semiconductor material, and the smaller periphery portion;

    the larger periphery portion causes the frozen large single crystal to have a bulge in a portion of its outer periphery, whereby, when the molten semiconductor material freezes, the bulge in the outer periphery of the frozen semiconductor crystal nests against the step portion around the inner surface of the crucible, thereby to prevent molten encapsulant material from flowing between the semiconductor crystal and the crucible.

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