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. 22, 2003
Filed:
Aug. 17, 1999
Haiming Wang, Fremont, CA (US);
Shing Lee, Fremont, CA (US);
Mehrdad Nikoonahad, Menlo Park, CA (US);
KLA-Tencor Corporation, San Jose, CA (US);
Abstract
Thickness of a film in a sample may be detected by directing pump laser pulses to the surface of a sample to generate an acoustic pulse in a sample. The acoustic pulse propagates downwards until it reaches an interface between the bottom of the film and a substrate and is reflected back to the top surface of the film as a first echo. A reflection of the first echo propagates downwards and is again reflected back towards the surface as a second echo. Heterodyne interferometry is used to measure the lapse of time between the first and second echos from which the thickness of the film may be determined.