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:
Dec. 30, 1986
Filed:
Aug. 19, 1985
Donald G Chesebro, Colchester, VT (US);
Robert W Sweetser, Essex Junction, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method of enhancing first order alignment marks formed in the respective layers of a processed semiconductor wafer in which critical masking steps are carried out. After a given mark is formed, it is tested for visual contrast. If the contrast is insufficient to provide adequate alignment, a block mask is formed on the critical mask. The block mask exposes all of the alignment target areas and protects the product regions of the wafer, and the critical mask only exposes the mark to be enhanced. The mark is then etched for a time period which is a function of the measured visual contrast. This method of selectively enhancing selected ones of the first order alignment marks greatly enhances the utility of such marks, increasing the accuracy of critical masking steps.