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:
Aug. 13, 1985
Filed:
Jun. 14, 1984
Applicant:
Inventor:
Paul E Cade, Colchester, VT (US);
Assignee:
International Business Machines Corporation, Armonk, NY (US);
Primary Examiner:
Int. Cl.
CPC ...
H01C / ; H01L / ; H01L / ;
U.S. Cl.
CPC ...
148-15 ; 29574 ; 2957 / ; 148187 ; 357 91 ; 427 531 ;
Abstract
A laser beam is used to scribe an alignment mark on the back side of a lightly doped substrate of a silicon wafer containing an heavily doped internal layer. The wavelength of the laser beam is chosen such that it passes through the lightly doped substrate without absorption but is absorbed in the heavily doped internal layer to produce therein a defect which has the same position as the scribed alignment mark. Subsequent heating of the wafer causes the defect to migrate upwardly through a lightly doped epitaxial layer to the front side of the wafer and produce therein a visible mirror image of the scribed alignment mark.