As the increasing demand of thinner CD for higher IC density and faster signal response, the techniques, such as OPC, PSM, and OAI was introduced to extend the optical resolution-limit below sub-100-nano. The lens quality is more important as critical dimension (CD) becomes smaller even using scanner instead of stepper. Pattern displacement error (PDE) resulting from lens aberration will be a phenomenon worthy to emphasize when technology design rules reaches sub-quarter micron generation and beyond1, 2. Because of inevitable coma aberration of lens, conventional 2úgm bar-in-bar overlay pattern cannot accurately represent real displacement of fine patterns in device. In this paper, evaluation of overlay pattern displacement with respect to lens coma aberration and its dependence on different feature size and structure are carried out. Different generation technology should combine with overlay pattern of proper feature size. Several illumination methodologies and NA/Sigma setting are also discussed in this paper.

Date Published: 16 July 2002
PDF: 6 pages
Proc. SPIE 4689, Metrology, Inspection, and Process Control for Microlithography XVI, (16 July 2002); doi: 10.1117/12.473467

Published in SPIE Proceedings Vol. 4689:
Metrology, Inspection, and Process Control for Microlithography XVI
Daniel J. C. Herr, Editor(s)