Tritone inspection for embedded phase shift mask

Embedded phase shift masks (ePSM) are critical to patterning the contact layer of integrated circuit devices of 130 nm technology node and beyond. Required ePSM inspection methodologies needed for the successful manufacturing of a "defect-free" ePSM are discussed in this study. We present an analysis of different inspection schemes for handling inspection system optical signals from tritone ePSM. Programmed defect ePSM plates with 6% shifter material transmission fabricated for 248 nm and 193 nm wafer exposures are characterized by metrology tools and inspected on existing optical mask inspection systems, Capture rates for various defect types are analyzed. The results of inspection sensitivity analysis are also compared with the defect specifications based on a defect printability simulation study, Key challenges ternary ePSM inspection are also discussed.