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:
Aug. 02, 1977
Filed:
Jun. 21, 1976
Hans Peter Kleinknecht, Bergdietikon, CH;
RCA Corporation, New York, NY (US);
Abstract
A technique for optically monitoring the undercutting of a layer of material being selectively etched beneath a pattern of masking material in an etchant comprises forming on a layer of the material being etched a diffraction grating pattern including spaced strips of masking material having a strip width W, exposing the diffraction grating pattern, while positioned in the etchant, to a beam of monochromatic light, whereby the grating pattern together with the layer of material therebeneath functions as a relief pattern which diffracts the beam of light into diffracted beams of various orders, and then monitoring certain of said diffracted beams to determine when a sharp decrease in the intensity thereof occurs, such a sharp decrease indicating an undercutting equal to a distance of W/2.