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:
Jun. 12, 2007
Filed:
Jun. 02, 2004
Abdurrahman Sezginer, Los Gatos, CA (US);
Hsu-ting Huang, San Jose, CA (US);
Kenneth Johnson, Santa Clara, CA (US);
Abdurrahman Sezginer, Los Gatos, CA (US);
Hsu-Ting Huang, San Jose, CA (US);
Kenneth Johnson, Santa Clara, CA (US);
Tokyo Electron Limited, Tokyo, JP;
Abstract
A method for measuring overlay in semiconductor wafers includes a calibration phase in which a series of calibration samples are analyzed. Each calibration sample has an overlay that is known to be less than a predetermined limit. A difference spectrum for a pair of reflectively symmetric overlay targets is obtained for each calibration sample. The difference spectra are then combined to define a gross overlay indicator. In subsequent measurements of actual wafers, difference spectra are compared to the overlay indicator to detect cases of gross overlay.