IMAGE MONITOR FOR MARKLE-DYSON OPTICS

A method for characterizing the performance of a lithographic imaging system has been devised which is independent of resist processing. A s canned grating technique has been adopted for measuring modulation as a function of both spatial frequency and defocus and it has been appli ed to the Markle-Dyson prototype (lambda=248 nm, NA=0.7) previously de scribed. A theoretical model based on Hopkins' formulation of partiall y coherent imaging was developed and showed agreement with measurement within experimental uncertainty. This demonstrates that the optics ar e indeed diffraction limited and are operating to specification.