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. 29, 2014
Filed:
Jun. 10, 2010
Stanley E. Stokowski, Danville, CA (US);
Stanley E. Stokowski, Danville, CA (US);
KLA-Tencor Corporation, Milpitas, CA (US);
Abstract
Provided are novel inspection methods and systems for inspecting unpatterned objects, such as extreme ultraviolet (EUV) mask blanks, for surface defects, including extremely small defects. Defects may include various phase objects, such as bumps and pits that are only about 1 nanometer in height, and small particles. Inspection is performed at wavelengths less than about 250 nanometers, such as a reconfigured deep UV inspection system. A partial coherence sigma is set to between about 0.15 and 0.5. Phase defects can be found by using one or more defocused inspection passes, for example at one positive depth of focus (DOF) and one negative DOF. In certain embodiments, DOF is between about −1 to −3 and/or +1 to +3. The results of multiple inspection passes can be combined to differentiate defect types. Inspection methods may involve applying matched filters, thresholds, and/or correction factors in order to improve a signal to noise ratio.