SILICON ON QUARTZ REFLECTIVE MASKS FOR 0.25-MU-M MICROLITHOGRAPHY

One approach to 0.25-mu-m lithography currently being explored is the unity-magnification Markle-Dyson projection system. This system, operating at lambda = 248 nm, incorporates a reflective mask in its design. This utilizes the internal reflection at the quartz/film interface. To best meet the requirements of high reflectivity and quarter micron processing, amorphous silicon on quartz masks were chosen. Completed masks were used to print 0.19-mu-m lines and spaces on the prototype Markle-Dyson system, demonstrating the feasibility of silicon reflective masks for lithography.