Patterning scaling trends are expected to continue until at least the 5 nm node. With the introduction of EUV
now delayed until at least the 7 nm node, 193i patterning will continue mainstream use for the foreseeable
future. This scaling increases reliance on optimized OPC and illumination and imposes strict requirements on
RET solutions, which we define here as source, optics, and mask synthesis (including SRAF). Along with the
patterning requirements, any solution must be calculated efficiently. To meet these requirements, a new RET
Selection flow has been built using the Calibre platform. This flow includes SMO, Mask synthesis to further
tune the output mask, Verification, and Analysis. The entire flow is session based, allowing runs to be cloned,
queued, and compared. The flow is built on a robust GUI framework featuring persistent database integration.
The central component of the flow is a new SMO algorithm that offers improved scalability using parallel
implementation, and improved accuracy using thick mask modeling and resist models. Lithography-aware mask
manufacturability limit enforcement is possible using an integrated inverse lithography tool. This also allows
large area patterns to be included for RET benchmarking purposes. Finally, the analysis and visualization stages
of the flow allow a particular solution to be compared against other candidates using any image metric desired.
Comparison metrics can be customized for layer and customer requirements. In this paper, we will summarize
the key points of our flow, and demonstrate it using several experiments.