The Impact and Optimization of EUV Sensitive Si Hardmask for Sub-20nm Patterning in EUVL with NTD Process

The impact of EUV sensitive spin-on silicon hardmask (Si-HM) on EUV lithography have been tested in negative tone development (NTD) process. In the EUV sensitive Si-HM, we have confirmed that EUV chromophore (EC) unit is effective to improve resolution and process margin because it absorbed EUV light efficiently and promoted the acid generation from photo-resist. Moreover, radical generation (RG) unit was also effective to improve lithographic performance because it could assist more acid generation from photo-resist. Using the optimized EUV sensitive Si-HM, EUV lithography in the NTD process was investigated and hp22nm L/S patterning could be achieved successfully. The optimized EUV sensitive Si-HM have also been tested on EUV lithography in positive tone development (PTD) process. Hp24, 26nm L/S patterning could be achieved and photo-speed and DOF margin were improved compared to standard Si-HM. Our EUV sensitive Si-HM could be revealed to show process universality both of PTD and NTD processes.