Report of latent contamination factors inducing lithographic variation

摘要

We have investigated the factors having influence on the lithographic fidelity variation in 193nm masks. Significantresearches have been studied that haze contamination, resulting from the absorption of chemical residual ions and maskcontainer out-gassing in mask fabrication, is one of the major component to reduce the optimized lithography conditionsuch as Best Focus, Depth of Focus and Exposure latitude of individual feature. And also environment being containinghumidity, ambient AMC (airborne molecular contamination) react with high exposure energy to form crystal growth ofionic molecular complex such as ammonium sulfate causing abnormal printability. Moreover, optical issue of organicpellicle membrane is thoroughly considered that perfluoro polymer degradation induced by high photon energy affect thetransmittance intensity. Consequently, these photophysical alterations bring about the lithographic variation and causeconsiderable defects in wafer printing. In this paper, we tried to verify the influence grade inducing the lithographic variation among the latent contaminationfactors consisting of mask back-side quartz contamination, the growth of exposure energy based haze phenomena, thinorganic pellicle membrane degradation and modified character of MoSiN surface. Metrological inspection andphotochemical 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 variationand latent contamination factors. The optical issues and lifetime of ArF PSM were simulated with the evaluation ofeffects of pellicle degradation and surface modification.