Monitoring EUV Reticle Molecular Contamination on ASML's Alpha Demo Tool - (PPT)

摘要

Contamination risk to EUV reticle of up to 1600J/cm~2 of exposure dose in ASML's ADT is negligible. Carbon contaminants & oxides are observed on exposed & unexposed Si surfaces of CM open fields and Ta surfaces of absorbers. Carbon thickness is < 0.5 nm on exposed & unexposed Si surfaces of CM open fields and Ta surfaces of absorbers. The Si capping layer in the CM open fields is oxidized to a thickness of around ～1 nm in both exposed and unexposed areas. The slightly lower amount of carbon contaminant in the exposed areas relative to the unexposed areas may be indicative of in-situ cleaning mediated by the interaction of EUV photons & residual oxygen in the reticle space. There is comparable level of reflectivity between exposed & unexposed CM open fields at the end of experiment, corresponding to a reflectivity loss of ～3% relative to pristine values. No discernible CD difference between gratings in the exposed & unexposed regions of the reticle is observed. 1600 J/cm~2 of EUV exposure dose can support ～620 printed wafers (with 72 exposure fields)@a resist sensitivity of 15mJ/cm~2.