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:
Apr. 07, 1981
Filed:
Dec. 29, 1978
Joseph P Kirk, Chelsea, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
An improved interferometer system for detecting the etch rate of an opaque material, such as silicon or metal. The system includes means for producing two parallel beams of light, with one beam being directed to the surface of the opaque material, and the other beam being directed to the surface of an adjacent masking material of transparent nature. The rate of etch of the opaque material is detected from the interference pattern changes between the first beam and the second beam. The system utilizes a novel arrangement of beam splitters which results in equal path lengths for the respective beams and further includes a viewing light which is passed by a system of dichroic filters to enable observation of the focus spot.