Apparatus and method for controlling thickness of a crystalline sheet grown on a melt

A system for growing a crystalline sheet from a melt, comprising:

• a crucible configured to contain the melt, the melt having an exposed surface that is separated from a floor of the crucible by a first distance;
• a crystallizer configured to generate a crystallization front of the crystalline sheet along a surface of the melt at a first position;
• a crystal puller configured to pull the crystalline sheet along a pull direction, wherein at a second position downstream of the crystallizer the crystalline sheet has an initial thickness profile along a transverse direction that is perpendicular to the pull direction;
• and
• a segmented heater downstream of the second position, the segmented heater comprising:
• a housing;
• and
• a plurality of heating elements disposed along the transverse direction, wherein the housing is disposed between the plurality of heating elements and the melt, wherein the plurality of heating elements are disposed at a second set of distances with respect to the exposed surface of the melt that are less than the first distance, and
• wherein the plurality of heating elements are configured to vary a heat flux profile along the transverse direction so as to melt back the crystalline sheet to generate at a third position downstream of the second position, a final thickness profile along the transverse direction that is more uniform than the initial thickness profile.

A method for controlling thickness of a crystalline sheet, comprising:

• generating a crystallization front of the crystalline sheet on a surface of a melt using a crystallizer;
• pulling the crystalline sheet away from the crystallization front along a pull direction, wherein at a first position downstream of the crystallization front, the crystalline sheet has an initial thickness profile along a transverse direction that is perpendicular to the pull direction;
• and
• melting back the crystalline sheet over a melt-back region using a plurality of heating elements disposed adjacent the crystalline sheet at different positions along the transverse direction, wherein the plurality of heating elements are disposed at a set of distances from the surface of the melt that are less than a melt depth of a crucible containing the melt;
• wherein the plurality of heating elements are configured to vary a heat flux profile along the transverse direction so as to melt back the crystalline sheet to generate, in the crystalline sheet at a position downstream of the melt back region, a final thickness profile along the transverse direction that is more uniform than the initial thickness profile.