Method and apparatus for growing shaped crystals
AssigneeCrystal Systems, Inc.
InventorsFrederick Schmid, Chandra P. Khattak, Vladimir Gorbulev
Life of this patent
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Abstract
A high temperature heat exchanger is used with the Czochralski crystal growing method to control the heat extraction from crystal silicon ingots as they are grown. The high temperature heat exchanger also acts as a shaping die so that silicon bars, or ingots, of various shapes, including square, circular, rectangular or ribbon, can be produced by shaping during the growth stage.
Claims15
In a crystal growth process wherein a solid material is forming by drawing upwardly from a melt, that improvement comprising the steps of:
- providing an elongated heat exchanger above said melt, said heat exchanger having an inside wall portion defining a passage having an axis extending generally upwardly from said melt through which material may be drawn and an outside wall portion;
- drawing said solid material upwardly through said passage of said heat exchanger along said axis in close proximity to said inside wall portion of said heat exchanger;
- and,
- controlling the extraction of heat from said solid material to said heat exchanger as it is drawn through said heat exchanger by producing in said heat exchanger a temperature gradient along the length of said heat exchanger, said gradient being such that the temperature of said interior wall portion of said heat exchanger is greatest adjacent said melt and decreases as the distance from said melt increases.
In a crystal growth process wherein a solid material is forming by drawing upwardly from a melt, that improvement comprising the steps of:
- providing an elongated heat exchanger above said melt, said heat exchanger having an inside wall portion defining a passage having an axis extending generally upwardly from said melt through which material may be drawn and an outside wall portion;
- drawing said solid material upwardly through said passage of said heat exchanger along said axis in close proximity to said inside wall portion of said heat exchanger;
- and,
- controlling the extraction of heat from said solid material to said heat exchanger as it is drawn through said heat exchanger by producing in said heat exchanger a temperature gradient along the length of said heat exchanger,
- said gradient being such that the temperature of said interior wall portion of said heat exchanger is greatest adjacent said melt and decreases as the distance from said melt increases,
- said heat exchanger having a fluid flow channel located on the side of said inner wall portion opposite said solid material and extending from a point spaced from said melt to a point nearer said melt, and
- said heat extraction being controlled by causing fluid to flow in said channel from said point spaced from said melt to said point nearer said melt, the temperature of said fluid at said point spaced from said melt being less than the temperature of said fluid at said point nearer said melt.
In a crystal growth process wherein a solid material is forming by drawing upwardly from a melt, that improvement comprising the steps of:
- providing an elongated heat exchanger above said melt, said heat exchanger having an inside wall portion defining a passage having an axis extending generally upwardly from said melt through which material may be drawn and an outside wall portion;
- drawing said solid material upwardly through said passage of said heat exchanger along said axis in close proximity to said inside wall portion of said heat exchanger;
- and,
- controlling the extraction of heat from said solid material to said heat exchanger as it is drawn through said heat exchanger by producing in said heat exchanger a temperature gradient along the length of said heat exchanger,
- said gradient being such that the temperature of said interior wall portion of said heat exchanger is greatest adjacent said melt and decreases as the distance from said melt increases, and
- the cross-sectional area and outer periphery of said heat exchanger in planes generally perpendicular to said axis being greater in a said plane spaced from said melt than in ones of said planes nearer said melt whereby the cross-section of said heat exchanger for heat conduction and the external surface area of said heat exchanger for radiation increases as the distance from the melt increases.
Dependencies are inferred from the claim text.