Japanese Journal of Applied Physics · 1996 · 11 citations · 4 references
Natural SciencesMaterials EngineeringMaterials ScienceOptical MaterialsOpticsPhotonicsMask DesignMask FabricationOptical Thin FilmsRefractive IndexThin Film Optical PropertiesAttenuated Phase Shift MasksOptical Absorption CoefficientPhase Shift MasksPhase-shift LithographyRefractive Index Engineering
Chromium fluoride (CrF) film was chosen as the phase shifter for attenuated phase-shifting masks because of its high transmittance at 193 nm. The refractive index n and absorption coefficient k was derived by using the reflectance-transmittance (RT) method. Using argon fluoride (ArF) excimer laser exposure equipment and a chemically amplified positive resist, fine hole patterns were resolved. Depth of focus (DOFs) with 0.24 µm were extended to 30%. The resolution limit was 0.20 µm, while it was 0.22 µm with a conventional mask.
4