The ALTA 4700 incorporates new optical subsystems to improve pattern quality performance and has added the capability to do variable multipass printing. The optical system changes are the addition of a 0.9-NA reduction lens and a new AOD subsystem to reduce beam placement and intensity errors. Variable multipass printing allows two-, four- or eight-pass printing, thereby enabling the user to optimize the pattern quality/throughput tradeoff. Local CDU 3σ performance for one pattern is reduced from 8.2 to 5.1 to 3.4 nm as the number of passes is increased from two to four to eight. Reduction of CDU performance is more pattern dependent going from four to eight passes than going from two to four passes. Pattern write times scale roughly linearly with the number of passes. Local pattern loading effects can limit global CDU performance. These effects can be reduced by optimizing resist selection and develop processes.

Date Published: 4 November 2005
PDF: 7 pages
Proc. SPIE 5992, 25th Annual BACUS Symposium on Photomask Technology, 59920W (4 November 2005); doi: 10.1117/12.633049

Published in SPIE Proceedings Vol. 5992:
25th Annual BACUS Symposium on Photomask Technology
J. Tracy Weed; Patrick M. Martin, Editor(s)