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:
Nov. 09, 1999
Filed:
Feb. 09, 1999
Thomas Evans Adams, Emmaus, PA (US);
Lucent Technologies, Inc., Murray Hill, NJ (US);
Abstract
A method to achieve good stepper focus and exposure over an entire wafer for a particular mask level before the start of a product run is described. This method can also be used to produce a characterization of lens field curvature (i.e., a surface of optimum focus across the lens) and to characterize lens astigmatism, defocus sensitivity, relative resolution, and other characteristics, and to check the stepper for optical column tilt. The process prevents the complexities of resist development from affecting determination of focus. The process involves forming an array of latent images in a resist and examining the scattered light from the edges of the latent images. Analysis of the scattered light quickly provides information on correct exposure and focus together with lens characteristics over the printing field.