Phase defect inspection by differential interference

Kiyoshi Ogawa; J. Kodama; K. Machida; Katsuyoshi Nakashima; Yaichiro Watakabe

doi:10.1117/12.438389

5 September 2001 Phase defect inspection by differential interference

Kiyoshi Ogawa, J. Kodama, K. Machida, Katsuyoshi Nakashima, Yaichiro Watakabe

Proceedings Volume 4409, Photomask and Next-Generation Lithography Mask Technology VIII; (2001) https://doi.org/10.1117/12.438389
Event: Photomask and Next Generation Lithography Mask Technology VIII, 2001, Kanagawa, Japan

Abstract

Photomask pattern inspection using transmitted light and/or reflected light is commonly used for Die to Die or Die to Database comparison method. We have applied the differential interference contrast method to phase defect inspection for alternating phase shifting mask (Alt-PSM). The key parameters for optics are resident phase in an interferometer, shearing direction and distance between two spots, which are determined by Nomarski prism design. Firstly, we studied defect image contrast by simulation. Chrome edge defects are more detectable than isolated center defects from the simulation result. Next, we configured a reflective type, differential interference optics using an Ar ion laser as a light source. A test mask having 70-degree phase defects on 520, 600, and 720 nm CD are inspected. Edge defects down to 520nm CD were detectable compared with conventional reflective method.

Citation Download Citation

Kiyoshi Ogawa, J. Kodama, K. Machida, Katsuyoshi Nakashima, and Yaichiro Watakabe "Phase defect inspection by differential interference", Proc. SPIE 4409, Photomask and Next-Generation Lithography Mask Technology VIII, (5 September 2001); https://doi.org/10.1117/12.438389

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