To enable Inverse Lithography Technology (ILT) for production as one of the leading candidates for low-k1 lithography
at 32nm and below, one major task to overcome is mask manufacturability including mask data fracturing, MRC
constraints, writing time, and inspection. In prior publications[1,2], it has been shown that the Inverse Synthesizer (ISTM)
produces ILT full chip mask of contact layer with comparable mask write time with conventional OPC while
maintaining the significant litho gains of ILT mask.
To fully integrate ILT masks into production for all layers including line and space layers such as poly layer, a number of
areas were investigated to further reduce ILT mask complexity and total e-beam shot count. These areas include flexible
controls of SRAF placements with respect to local feature sizes, improved Manhattan algorithm, topology based variable
Manhattan segmentation, jog alignment and mask data fracture optimization. The impact of these approaches on e-beam
shot count and lithography performance of ILT masks is presented in the paper.