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:
Jan. 02, 1990
Filed:
May. 25, 1989
Whitson G Waldo, III, Chandler, AZ (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
The contrast of a photoresist layer used in a lithographic process for a given light source is optimized by determining the nonlinear relationship of the photoresist contrast with regard to the thickness thereof and then placing over a substrate a thickness of photoresist corresponding to a desired value of contrast indicated by the nonlinear relationship of contrast with photoresist thickness. The nonlinear contrast with regard to photoresist thickness function is a damped, sinusoidal like function with the difference between maxima and minima contrast values decreasing as the photoresist thickness increases and with higher absolute maxima values for contrast as photoresist thickness decreases. The amount of light needed to fully expose a given thickness of photoresist also varies with the photoresist thickness in a sinusoidal like manner and a phase difference may exist between the sinusoidal like contrast versus photoresist thickness function and the sinusoidal like exposing light versus photoresist thickness function. It is possible that the light source and the photoresist characteristics can be selected to product a predetermined phase difference.