| US 7,508,526 B2 | ||
| Defect inspecting apparatus | ||
| Riki Ogawa, Kawasaki (Japan); Toru Tojo, Naka-gun (Japan); and Munehiro Ogasawara, Hiratsuka (Japan) | ||
| Assigned to Kabushiki Kaisha Toshiba, Tokyo (Japan) | ||
| Filed on Oct. 14, 2005, as Appl. No. 11/249,359. | ||
| Claims priority of application No. 2004-300266 (JP), filed on Oct. 14, 2004. | ||
| Prior Publication US 2006/0082782 A1, Apr. 20, 2006 | ||
| Int. Cl. G01B 9/02 (2006.01); G01B 11/02 (2006.01) | ||
| U.S. Cl. 356—491 [356/511] | 10 Claims |
| 1. An apparatus for inspecting a defect in a pattern formed on a mask, comprising:
a differential interference optical system having an optical axis, which includes:
a first birefringence prism configured to separate light rays into first ordinary and extraordinary light ray components which
are separated in a first predetermined direction and are directed to the mask, the first ordinary and extraordinary light
ray components emerging from the mask forming a first differential interference image, and
a second birefringence prism configured to separate light rays into second ordinary and extraordinary light ray components
which are separated in a second predetermined direction different from the first predetermined direction and are directed
to the mask, the second ordinary and extraordinary light ray components emerging from the mask forming a second differential
interference image;
first and second image pickup sensors configured to pick up the first and second differential interference images, respectively;
and
a defect detecting unit configured to detect a defect in the pattern formed on the mask by comparing the first and second
differential interference images with first and second reference images, respectively.
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