Continuous downward pressure on chip size has led to aggressive ground rule shrink paths in the semiconductor industry, especially in the DRAM sector. Ever-decreasing feature sizes have necessitated the extensive use of attenuated phase shift masks, off-axis illumination, optical proximity correction, etc. For the foreseeable future, the ability to meet the demands of the design is closely tied to the extendibility of ArF lithography. This paper explores DRAM lithographic scaling by predicting required process latitude and depth of focus based on litho-graphic merit function scaling. This allows the predictions to be anchored against data collected on current products, as well as indicating the rate at which learning must occur for a ground rule shrink to be successful. Modeling of ArF extendibility is presented, with particular emphasis on the role of alternating phase shift masks. Additionally, simple signal-to-noise argu-ments are made in connection with the required process window for a given technology, taking into the account fundamental error sources of the process. The analyses are anchored to existing technologies wherever possible. The results indicate that ArF lithography will extend through the 90 nm technology node with a critical dependence on alternating phase shift masks.

Date Published: 14 September 2001
PDF: 7 pages
Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001); doi: 10.1117/12.435722

Published in SPIE Proceedings Vol. 4346:
Optical Microlithography XIV
Christopher J. Progler, Editor(s)