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:
Jul. 02, 1996
Filed:
Dec. 23, 1993
William J Adair, Underhill, VT (US);
Timothy A Brunner, Ridgefield, CT (US);
Derek B Dove, Mt. Kisco, NY (US);
Louis L Hsu, Fishkill, NY (US);
Chi-Min Yuan, Austin, TX (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A simplified method of forming a phase shift structure for a lithographic mask includes the conformal deposition of a phase shift material, preferably having an index of refraction similar to that of the mask substrate, over a patterned layer of opaque material and exposed areas of the mask substrate corresponding to the pattern. The thickness of the opaque patterned layer, in combination with the conformal deposition preferably establishes a differentially altered optical path length to produce a phase shift which enhances contrast and increases illumination and resolution in fine patterns. In variant forms of the invention, the conformal deposition of either phase shift material or a sidewall spacer material is followed by an anisotropic removal of material to form the phase shift structure. The application of phase shift material over the mask surface increases durability of the mask and also enhances contrast of images produced with other phase-shift mask feature structures, such as Levenson-type shifters.