Ribbon crystal string for increasing wafer yield

Abstract

A ribbon crystal has a body with a width dimension, and string embedded within the body. The string has a generally elongated cross-sectional shape. This cross-section (of the string) has a generally longitudinal axis that diverges with the width dimension of the ribbon crystal body.

1 . A method of forming a ribbon crystal, the method comprising:
 providing a set of strings that each have a generally elongated cross-sectional shape, the cross-section of each string having a generally longitudinal axis;   adding molten material to a crucible;   passing the set of strings in a given direction through the molten material; and   causing the molten material to freeze above an interface to form a sheet, the sheet having a width dimension that is generally perpendicular to the given direction of the set of strings,   at least one string being oriented so that its longitudinal axis diverges with the width dimension of the sheet.   
     
     
         2 . The method as defined by  claim 1  wherein the set of strings comprises at least two strings. 
     
     
         3 . The method as defined by  claim 1  wherein passing comprises passing two strings in the given direction through the molten material, the width dimension being generally defined by the two strings, the two strings being oriented so that each of their longitudinal axes diverges with the width dimension of the sheet. 
     
     
         4 . The method as defined by  claim 1  wherein the molten material comprises a silicon-based material. 
     
     
         5 . The method as defined by  claim 1  wherein the cross-sectional shape of the set of strings is a general ellipsoid or a rectangle. 
     
     
         6 . The method as defined by  claim 1  wherein the cross-sectional shape of the set of strings has a long dimension that is generally parallel with the longitudinal axis, a cross-sectional shape of the set of strings also having a short dimension that is generally perpendicular to the long dimension, the short dimension being generally irregular. 
     
     
         7 . The method as defined by  claim 1  wherein the cross-sectional shape of the set of strings is generally convex. 
     
     
         8 . The method as defined by  claim 1  wherein the cross-sectional shape of the set of strings is generally concave.