Process and device for pulling crystals according to the Czochralski method
OwnerHans L. Scheelinventor
Life of this patent
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Abstract
A process and apparatus for growing a crysrtal by the Czochralski method, in which a melt is disposed in a crucible, partitioned into an outer annular portion and an inner cylindrical portion by an annular separation element which is open at its bottom, the open bottom being spaced from the bottom of the crucible. The separation element is rotated on its vertical axis and a crystal is pulled from the melt in the inner cylindrical portion by raising a crystal holder, which is also rotated, in the vertical direction. The melt required for growing the crystal flows from the outer annular portion to the inner cylindrical portion over the entire cross-section of the inner cylindrical portion at the bottom of the annular separation element.
Claims17
A process for growing a crystal by the Czochralski method, comprising the steps of:
- a) disposing the melt in a crucible open at its top and having a floor at its bottom;
- b) partitioning the crucible into an outer annular portion and an inner cylindrical portion with an annular separation element open across its entire cross-section at its bottom, said open bottom being spaced from the bottom of the crucible;
- c) rotating the separation element on its vertical axis at a speed .omega..sub.1 ;
- d) pulling a crystal from the melt in the inner cylindrical portion by raising a crystal holder in a vertical direction;
- and
- e) rotating the crystal holder on its vertical axis at a speed .omega..sub.2 during the pulling:
- wherein the melt required for growing the crystal flows over the entire open cross-section of the inner cylindrical portion at the bottom of the annular separation element.
Apparatus for growing crystal by the Czochralski method, comprising:
- a) a crucible having an outer wall, a bottom floor and an open top, for containing a melt;
- b) a crystal holder positioned for pulling a crystal upwardly from the melt in the crucible;
- c) means for moving said crystal holder vertically;
- d) means for rotating said crystal holder on its vertical axis;
- e) an annular separation element formed of a peripheral wall and being open across its entire cross-section at its bottom, said separation element being positioned in said crucible coaxial with the crystal holder, with the bottom spaced from the bottom floor of the crucible;
- and
- f) means for rotating the annular separation element on its vertical axis in the same direction as the crystal holder.
Dependencies are inferred from the claim text.