Report of latent contamination factors inducing lithographic variation

We have investigated the factors having influence on the lithographic fidelity variation in 193nm masks. Significant researches have been studied that haze contamination, resulting from the absorption of chemical residual ions and mask container out-gassing in mask fabrication, is one of the major component to reduce the optimized lithography condition such as Best Focus, Depth of Focus and Exposure latitude of individual feature. And also environment being containing humidity, ambient AMC (airborne molecular contamination) react with high exposure energy to form crystal growth of ionic molecular complex such as ammonium sulfate causing abnormal printability. Moreover, optical issue of organic pellicle membrane is thoroughly considered that perfluoro polymer degradation induced by high photon energy affect the transmittance intensity. Consequently, these photophysical alterations bring about the lithographic variation and cause considerable defects in wafer printing. In this paper, we tried to verify the influence grade inducing the lithographic variation among the latent contamination factors consisting of mask back-side quartz contamination, the growth of exposure energy based haze phenomena, thin organic pellicle membrane degradation and modified character of MoSiN surface. Metrological inspection and photochemical reaction evaluations were conducted with several equipments including AIMS, Scatterometer, XPS, SIMS, FT-IR, UV, ArF acceleration laser to demonstrate the proposal mechanism of correlation between lithographic variation and latent contamination factors. The optical issues and lifetime of ArF PSM were simulated with the evaluation of effects of pellicle degradation and surface modification.