| 摘要 |
Methods of growing crystals by the Czochralski method in which a member having a central vertical passageway extending through it is floated on the melt, and the crystallization is caused to take place within this passageway. The passageway may be parallel sided or tapering from top to bottom and is such that the melt does not wet the walls of the passageway. Excellent diameter control of the grown crystal is obtainable, and since the member floats on the melt during crystallisation, its position follows changes in the level of the melt as the material is pulled from the melt. In one embodiment, the member is porous and fluid is forced through the porous wall of the passageway from a cavity within the member to form a barrier to keep the melt out of contact with the wall of the passageway. In another embodiment, a liquid encapsulant is used, which forms a coating over the whole surface of the floating member including the wall of the passageway. The floating member can be made from a number of different materials, including graphite, silicon nitride, silicon carbide, boron nitride, silica beryllia. The crystal may be rotated as pulled, in which case a centering device may be provided to maintain the axis of the passageway coincident with the axis of rotation of the crystal.
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