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. 19, 1997
Filed:
Sep. 29, 1995
Philippe Coronel, Massy, FR;
Jean Canteloup, Montlhery, FR;
International Business Machines Corporation, Armonk, NY (US);
Abstract
Detecting the desired etch end point in the dry etching of a structure that includes a dielectric film formed onto a substrate down to a given thickness Ef. The structure is placed in the chamber of an etching equipment provided with a view-port. A light source illuminates a portion of the structure at a normal angle of incidence through the view-port. The light contains at least two specified wavelengths (L1, L2) whose value is greater than a minimum value equal to 4*N*e (wherein N is the index of refraction and e the thickness error of the dielectric). The reflected light is applied to spectrometers tuned to each specified wavelength, for converting the reflected light into interference signals that are processed and analyzed in a dedicated unit to generate primary signals (S1, S2). An analysis of the primary signals is performed after a predetermined delay. For each wavelength, a pre-selected extremum of the primary signal is detected and a predetermined number of extrema is counted. The counting stops when the last extremum just before Ef is reached. As a result, the distance D between the last extremum and the given thickness is now determined. The etch rate ER is also measured in-situ before the last extremum.