Programmed defects about 0.4 ?/NA in size are introduced in strong phase-shifting masks to produce exposure-sensitive printable artifacts for measuring lens aberrations. The programmed defects add interferrometric-like reference electric fields that coherently interact with the side-lobes of aberration sensitive pattern layouts to produce artifacts. The artifacts are separate but adjacent printed defects. The patterns are suitable for rapid reading by automatic wafer inspection equipment and directly indicate the levels of specific Zemike aberrations. High sensitivity to 0.01 X and good orthogonality with 12% confounding are possible for coma and trifoil. Results for even aberrations such as focus, astigmatism and spherical 3rd order are poor for 180° phase defect-probes but warrant further investigation with 90° phase.

Date Published: 22 January 2001
PDF: 10 pages
Proc. SPIE 4186, 20th Annual BACUS Symposium on Photomask Technology, (22 January 2001); doi: 10.1117/12.410717

Published in SPIE Proceedings Vol. 4186:
20th Annual BACUS Symposium on Photomask Technology
Brian J. Grenon; Giang T. Dao, Editor(s)