Traditional rule-based and model-based OPC methods only simulate in a very local area (generally less than 1um) to identify and correct for systematic optical or process problems. Despite this limitation, however, these methods have been very successful for many technology generations and have been a major reason for the industry being able to tremendously push down lithographic K1. This is also enabled by overall good across-exposure field lithographic process control which has been able to minimize longer range effects across the field. Now, however, the situation has now become more complex. The lithographic single exposure resolution limit with 1.35NA tools remains about 80nm pitch but the final wafer dimensions and final wafer pitches required in advanced technologies continue to scale down. This is putting severe strain on lithographic process and OPC CD control. Therefore, formerly less important 2nd order effects are now starting to have significant CD control impact if not corrected for. In this paper, we provide examples and discussion of how optical and chemical flare related effects are becoming more problematic, especially at the boundaries of large, dense memory arrays. We then introduce a practical correction method for these systematic effects which reuses some of the recent long range effect correcting OPC techniques developed for EUV pattern correction (such as EUV flare). We next provide analysis of the benefits of these OPC methods for chemical flare issues in 193nm lithography very low K1 lithography. Finally, we summarize our work and briefly mention possible future extensions.

Date Published: 12 April 2013
PDF: 11 pages
Proc. SPIE 8683, Optical Microlithography XXVI, 86830F (12 April 2013); doi: 10.1117/12.2012463

Published in SPIE Proceedings Vol. 8683:
Optical Microlithography XXVI
Will Conley, Editor(s)