24 March 2016 Controlling bridging and pinching with pixel-based mask for inverse lithography
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Abstract
Inverse Lithography Technology (ILT) has become a viable computational lithography candidate in recent years as it can produce mask output that results in process latitude and CD control in the fab that is hard to match with conventional OPC/SRAF insertion approaches.

An approach to solving the inverse lithography problem as a nonlinear, constrained minimization problem over a domain mask pixels was suggested in the paper by Y. Granik “Fast pixel-based mask optimization for inverse lithography” in 2006. The present paper extends this method to satisfy bridging and pinching constraints imposed on print contours.

Namely, there are suggested objective functions expressing penalty for constraints violations, and their minimization with gradient descent methods is considered. This approach has been tested with an ILT-based Local Printability Enhancement (LPTM) tool in an automated flow to eliminate hotspots that can be present on the full chip after conventional SRAF placement/OPC and has been applied in 14nm, 10nm node production, single and multiple-patterning flows.
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Sergey Kobelkov, Alexander Tritchkov, JiWan Han, "Controlling bridging and pinching with pixel-based mask for inverse lithography", Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 97782X (24 March 2016); doi: 10.1117/12.2219281; https://doi.org/10.1117/12.2219281
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