The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 04, 1994
Filed:
Sep. 01, 1992
Karlheinz Langsdorf, Burghausen, DE;
Wacker-Chemtronic Gesellschaft fur Elecktronik-Grundstoffe mbH, Burghausen, DE;
Abstract
Ingot-type semiconductor single crystals having diameters of more than 200 m can be sawed into thin wafers using an annular saw if the crystal is fed towards the cutting edge of the annular saw while rotating around its longitudinal axis. The method includes having a wafer sawed out in this way until a residual joint is created between a wafer and the end face of the ingot. Ingot and wafer are finally separated by means of a residue separation technique which leaves behind various central material projections on the ingot and the wafer. Particularly suitable for residue separation are torsion separation and separation by a wire saw. This procedure reliably prevents the frequently observable, uncontrollable breaking-off of the wafer in the final phase of the annular sawing if this is exclusively used as the method of separation. The method, whose final step involves the removal of the material projection on the wafer by rotation grinding, proves to be particularly suitable for crystals having diameters of more than 200 mm. In this case, the material saving is exceedingly high as a result of the absence of chips from the ingot or wafer as a consequence of uncontrolled breaking-off of the wafer.