US 2012/0067273 A1Published application

Methods for efficiently making thin semiconductor bodies from molten material for solar cells and the like

Assignee1366 Technologies, Inc.

InventorsEmanuel M. Sachs, Richard L. Wallace, Eerik T. Hantsoo, Adam M. Lorenz, G. D. Stephen Hudelson, Ralf Jonczyk

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Abstract

A pressure differential is applied across a mold sheet and a semiconductor (e.g. silicon) wafer (e.g. for solar cell) is formed thereon. Relaxation of the pressure differential allows release of the wafer. The mold sheet may be cooler than the melt. Heat is extracted almost exclusively through the thickness of the forming wafer. The liquid and solid interface is substantially parallel to the mold sheet. The temperature of the solidifying body is substantially uniform across its width, resulting in low stresses and dislocation density and higher crystallographic quality. The mold sheet must allow flow of gas through it. The melt can be introduced to the sheet by: full area contact with the top of a melt; traversing a partial area contact of melt with the mold sheet, whether horizontal or vertical, or in between; and by dipping the mold into a melt. The grain size can be controlled by many means.

Claims21

Dependent claims

A method for fabricating a semi-conductor body, the method comprising the steps of:

a. providing a molten semi-conductor material, having a surface;
b. providing a porous mold, comprising a forming surface;
c. providing a differential pressure regime such that pressure at at least a portion of the forming surface is less than pressure at the molten material surface;
d. contacting the forming surface to the molten material for a contact duration such that, for at least a portion of the contact duration:
i. the differential pressure regime is provided and;
ii. at least a portion of the forming face is at a temperature below a melting point of the semi-conductor material,
such that a body of semi-conductor material, solidifies upon the forming surface;
e. causing motion of the forming surface relative to the molten semi-conductor material, with the solidified body upon the forming surface;
and
f. reducing the degree of the differential pressure regime, thereby contributing to the solidified body detaching from the forming surface.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/299,031Filed 17 Nov 2011
Priority: 9 Mar 2009
Published: 22 Mar 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

B29C 33/44
Moulds or cores; Details thereof or accessories therefor: with means for, or specially constructed to facilitate, the removal of articles, e.g. of…
C30B 11/007
Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method: mechanisms for moving either…
C30B 15/30
Single-crystal growth by pulling from a melt, e.g. Czochralski method: mechanisms for rotating or moving either the melt or the crystal
C30B 19/068
Reaction chambers; Boats for supporting the melt; Substrate holders: substrate holders

Family

Application61/209,582Us provisional application · filed 9 Mar 2009
Application61/224,730Us provisional application · filed 10 Jul 2009
Application61/237,965Us provisional application · filed 28 Aug 2009
Application12/999,206Continuation · filed 28 Jun 2011
Application13/299,031Continuation
US 2011/0247549 A1Published application
US 8,293,009 B2Related patent
US 2012/0067273 A1This patent

From the US filing history. Foreign family members aren’t listed.