Double patterning (DP) is one of the main options to print devices with half pitch less than 45nm. The basis of DP is to decompose a design into two masks. In this work we focus on the decomposition of the contact pattern layer. Contacts with pitch less than a split pitch are assigned to opposite masks corresponding to different exposures. However, there exist contact pattern configurations for which features can not be assigned to opposite masks. Such contacts are flagged as color conflicts. With the help of design of manufacturing (DFM), the contact conflicts can be reduced through redesign. However, even the state of the art DFM redesign solution will be limited by area constraints and will introduce delays to the design flow. In this paper, we propose an optical method for contact conflicts treatment. We study the impact of the split on imaging by comparing inverse lithography technology (ILT), optical proximity correction (OPC) and source mask co-optimization (SMO) techniques. The ability of these methods to solve some split contacts conflicts in double patterning are presented.

Date Published: 30 September 2009
PDF: 7 pages
Proc. SPIE 7488, Photomask Technology 2009, 74882K (30 September 2009); doi: 10.1117/12.829762

Published in SPIE Proceedings Vol. 7488:
Photomask Technology 2009
Larry S. Zurbrick; M. Warren Montgomery, Editor(s)