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:
Jun. 15, 1993
Filed:
Dec. 20, 1991
Steven G Barbee, Dover Plains, NY (US);
Leping Li, New Paltz, NY (US);
Victor J Silvestri, Hopewell Junction, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
An interferometer 10 for measuring the position of the process surface 21 of a substrate 20 includes a coherent light source 12 for providing a light beam 14 which is partially transmitted and partially reflected by a beam splitter 16. The reflected light beam 18 is reflected off of the process surface 21 and the transmitted light beam 30 is reflected off of a translator 32 which vibrates a predetermined distance at a predetermined frequency. The phase shift between the light beams 22, 31 reflected off of translator 32 and the process surface 21 is measured using a photodetector 24, which provides an output signal 26 to a feedback servo unit 28. The servo unit 28 provides an output signal 38 which controls the vibration of translator 32. The output signal 38 of servo unit 28 is also indicative of the position of the process surface 21.