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:
Jan. 06, 2004
Filed:
May. 04, 2001
Matthias C. Krantz, Aptos, CA (US);
Mark Joseph Wihl, Tracy, CA (US);
Stanley E. Stokowski, Danville, CA (US);
KLA-Tencor Technologies Corporation, Milpitas, CA (US);
Abstract
The ability to inspect photomasks for errors or defects in phase-shifters is greatly enhanced using optical techniques based on multiple modified radiation collection techniques. In particular, the apparatus and methods of the invention allows for errors in phase-shifters to be more accurately detected, even in the presence of regular amplitude objects such as grid lines. In one embodiment, the intensities of two slightly defocused images of phase objects corresponding to the same photomask location are compared. In a second embodiment, radiation having two Zernike point spread functions is used to obtain two slightly different phase sensitive images. Data collected and analyzed using this method provides much greater sensitivity to phase objects and errors in phase objects than prior art inspection systems. Embodiments include both scanning-type and projector-type optical architectures and may utilize radiation transmitted or reflected by a sample.