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. 26, 2014
Filed:
Apr. 24, 2012
Hwan J. Jeong, Los Altos, CA (US);
Silvio J. Rabello, Palo Alto, CA (US);
Thomas Andre Casavant, Cupertino, CA (US);
Hwan J. Jeong, Los Altos, CA (US);
Silvio J. Rabello, Palo Alto, CA (US);
Thomas Andre Casavant, Cupertino, CA (US);
Nanometrics Incorporated, Milpitas, CA (US);
Abstract
A dark field diffraction based overlay metrology device illuminates an overlay target that has at least three pads for an axis, the three pads having different programmed offsets. The overlay target may be illuminated using two obliquely incident beams of light from opposite azimuth angles or using normally incident light. Two dark field images of the overlay target are collected using ±1diffraction orders to produce at least six independent signals. For example, the +1diffraction order may be collected from one obliquely incident beam of light and the −1diffraction order may be collected from the other obliquely incident beam of light. Alternatively, the ±1diffraction orders may be separately detected from the normally incident light to produce the two dark field images of the overlay target. The six independent signals from the overlay target are used to determine an overlay error for the sample along the axis.