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:
May. 17, 1988
Filed:
Nov. 10, 1986
Edward C Fredericks, Manassas, VA (US);
Giorgio G Via, McLean, VA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method which provides for a permanent planarization layer on a multilayer integrated circuit. The planarization layer resides above other circuit layers which reflect incident light. A layer of photoresist is formed over the planarization layers and imaged through a mask with circuit defining structure. During exposure of the photoresist, incident light passes through the planarization layer. Scattering from the boundary of the planarization layer and photoresist is minimized because the index of refraction of the planarization layer is substantially equal to the index of refraction of the photoresist. Light reflected from the underlaying layers is substantially absorbed by the planarization layer. Reduction of the reflected and scattered light results in improved resolution of developed images in photoresist. The developed images, when further processed into interconnecting conductors have improved definition, avoiding the additional process steps of applying a temporary dye or other light impervious layer.