Optical Microscopy at sub-0.1 μm Resolution: Fiction or Vision?

摘要

Until recently, optical microscopes enjoyed approximately a 1.6X resolution advantage over their stepper counterparts due to the microscopes' higher numerical aperture objectives [currently at 0.95] relative to the stepper lens' NA of ～0.65. As stepper optics transition from the violet part of the light spectrum (436 nm, g-line) to ultraviolet (UV, 365 nm, Mine) to deep UV (248 nm, KrF-line and 193 nm, ArF-line), microscopy's resolution advantage in the visible spectrum (400-700 nm) slowly diminishes. UV/DUV microscopes offer improved resolution, while further increases in NA are impractical due to the physical limitation of a maximum of NA = 1 for non-immersion lenses.