While the use of phase shift masks can improve CD control and allow the patterning of smaller poly gate features, it also introduces new error terms for overlay. Four error terms are discussed: increased sensitivity of image placement to coma-type aberrations, image placement shifts resulting form phase errors, image placement shifts resulting from intensity imbalance between zero and 180 degrees shifter regions, and phase shift mask to trim mask overlay issues. These overlay issues become increasingly important for lower k1 patterning. Likewise, phase defect printability is magnified for lower k1 patterning, increasing the requirements for phase shift mask inspection and repair.

Date Published: 5 July 2000
PDF: 9 pages
Proc. SPIE 4000, Optical Microlithography XIII, (5 July 2000); doi: 10.1117/12.388937

Published in SPIE Proceedings Vol. 4000:
Optical Microlithography XIII
Christopher J. Progler, Editor(s)