A Framework for Exploring the Interaction Between Design Rules and Overlay Control

Overlay control is becoming increasingly more important with the scaling of technology. It has become even more critical and more challenging with the move toward multiple-patterning lithography, where overlay translates into CD variability. Design rules and overlay have strong interaction and can have a considerable impact on the design area, yield, and performance. This paper offers a framework to study this interaction and evaluate the overall design impact of rules, overlay characteristics, and overlay control options. The framework can also be used for designing informed, design-aware overlay metrology and control strategies. In this work, The framework was used to explore the design impact of LELE double-patterning rules and poly-line end extension rule defined between poly and active layer for different overlay characteristics (i.e., within-field vs. field-to-field overlay) and different overlay models at the 14nm node. Interesting conclusions can be drawn from our results. For example, one result shows that increasing the minimum mask-overlap length by 1nm would allow the use of a thirdorder wafer/sixth-order field-level overlay model instead of a sixth-order wafer/sixth-order field-level model with negligible impact on design.