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:
Feb. 04, 1986
Filed:
Apr. 30, 1984
Dinesh A Badami, Williston, VT (US);
Mark C Hakey, Milton, VT (US);
Holger Moritz, Holzgerlingen, DE;
International Business Machines Corporation, Armonk, NY (US);
Abstract
An optical photolithographic process in which resist lines having widths in the micron and sub-micron range are produced without the use of a fine line photomask. A positive photoresist having an additive for image reversal is applied to the surface of a semiconductor substrate. The photoresist is exposed through a photomask to ultraviolet light. The edges of the opaque sections of the mask diffract the ultraviolet light, forming partially exposed areas between the exposed and unexposed areas formed in the photoresist. After development in a solvent to remove the exposed areas, the photoresist undergoes an image reversal process. The photoresist is first baked at 100.degree. C. for 30 minutes. During this bake step, the photoactive decomposition products present in the partially exposed areas react, freezing the solubility of the partially exposed areas with respect to that of the unexposed areas. The photoresist is then blanket exposed and developed in a solvent, leaving the partially exposed areas on the substrate. The resulting thin resist lines can be used to form narrow isolation trenches by coating the substrate with a quartz film and lifting off the resist lines.