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. 05, 1991
Filed:
Jun. 28, 1990
Michael Kallmeyer, Boeblingen, DE;
Dietmar Wagner, Stuttgart, DE;
International Business Machines Corporation, Armonk, NY (US);
Abstract
Method and an apparatus for determining line centers in a microminiature element such as on a semiconductor wafer or a mask having linewidths and other spacings below the one micron range. The invention uses, two focussed laser beams which are directed across a line on the element, both beams being illuminated successively with a distance therebetween below the classic resolving power. A portion of the incident beam and a portion of the beam reflected from the line is conducted to respective detectors which respectively generate measurement and reference signals. These signals are treated to eliminate high frequency noise components therein. Subsequently, the filtered measurement and reference signals are digitized and synchronously processed to provide two sine shaped curves whose intersection point corresponds to the center of the scanned line.