Enabling alternating phase shifted mask designs for a full logic gate level: Design rules and design rule checking

The International Technology Roadmap for Semiconductors lists F2 (λ = 157 nm) optical lithography and extreme ultraviolet next generation lithography as the two most feasible lithography solutions for the 70 nm technology node. It is likely that both of these solutions will be late, forcing ArF (λ = 193 nm) lithography to operate at unprecedented resolution levels. Theoretically, alternating phase shifted masks ("altPSM") can achieve the resolution required to manufacture 70 nm logic products with ArF lithography equipment, but technical and logistical challenges associated with the broad implementation of altPSM require novel and invasive EDA solutions which have caused the industry to shy away from altPSM in the past. One of the biggest such challenges is the creation of robust design rule checking (DRC) tools which can predict whether a given layout has a valid, manufacturable altPSM solution. This paper takes a detailed look at the technical and practical issues associated wit h altPSM design rules and DRC.