An update on the DPL overlay discontinuity

It could be argued that the biggest challenge of the 32 nm half pitch node is the production implementation of double patterning lithography. Within the framework of this broad domain, a specific challenge which has been highlighted is overlay control due to the sharing between two exposures the overlay control allocation of a single patterning step. The models used in the literature to support this assertion are reviewed and compared with recent results. An analysis of the implications for overlay metrology performance and cost of ownership is presented and compared with actual capabilities currently available with both imaging and scatterometry sensor technology. Technology matching between imaging and scatterometry emerges as a requirement to enable combined imaging scatterometry overlay control use cases.