QUARTZ ETCHING FOR PHASE-SHIFTING MASKS

In this paper a technology for dry etching of quartz for the fabrication of Phase Shift Masks (PSMs) and micromechanic applications is presented. Reactive Ion Etching (RIE) with CF4/SF6 +O2 chemistry and a chrome and/or resist/chrome mask is applied to quartz etching. Quartz structures and PSM with high resolution have been fabricated on commercially available chrome-quartz blanks. The chrome layer serves two purposes: first, it is used to define the structures with high resolution and low edge roughness, and second, it is used as an attenuating layer for rim-type PSM after wet etching or as a phase shifter in combination with the residual resist layer.