Experimental validation of stochastic modeling for negative-tone develop EUV resists

Line width roughness (LWR) remains a critical issue when moving towards smaller feature sizes in EUV lithography. At the same time, negative-tone develop (NTD) resist has become a promising process to get wide process margin at narrow trenches and for block mask layers in optical lithography. Here, we present a study on printing behavior of an EUV NTD resist which was exposed at IMEC on the AMSL NXE:3100 EUV tool. In particular, we analyzed the line width roughness, which was found to be pattern dependent. We calibrated a stochastic resist model to the experimental CD and LWR data. The resulting model was used to analyze and understand the pattern dependent LWR behavior. Simulation results for different LWR process window between iso trench, dense line and iso line was verified with measurement results.