Enhanced optical microlithography with a Fabry-Perot-based spatial filtering technique

A coherent multiple imaging technique for use in optical microlithography was studied. The technique involves placing a thin Fabry-Perot etalon between the mask and the projection lens of an optical stepper. An optical lithographic computer simulation tool, Prolith/2, was used to evaluate the aerial image profile obtained for extended mask structures such as typical contact hole arrays and line-space patterns used in integrated circuit fabrication. Additionally, a set of experimental studies were performed to validate the simulation results. Enhancement of both resolution and depth of focus can be obtained simultaneously with appropriate etalon parameters.