For next generation photo mask lithography the tolerance range for pattern placement and critical dimensions (CD) is further shrinking. Improved optical resolution and precision of a metrology system are required to qualify the lithography tool and monitor the photo mask process. Edge detection methods in transmitted light mode for pattern placement and CD measurements are advantageous if the tightened resolution and precision requirements can be met. The new LMS IPRO2 using an illumination wavelength range of 360 to 410 nm has a significantly enhanced resolution for registration and CD measurements in both, transmitted and reflected light. A new laser interferometer with an enhanced resolution of 0.3 nm contributes to the overall improved system performance. The stage is designed to measure on quartz substrates and next generation lithography (NGL) reticles up to 230 mm square in transmitted light as well as in reflected light on 200 mm and 300 mm wafers for stepper qualification.

Date Published: 1 August 2002
PDF: 11 pages
Proc. SPIE 4754, Photomask and Next-Generation Lithography Mask Technology IX, (1 August 2002); doi: 10.1117/12.476920

Published in SPIE Proceedings Vol. 4754:
Photomask and Next-Generation Lithography Mask Technology IX
Hiroichi Kawahira, Editor(s)