PATTERNING TUNGSTEN FILMS WITH AN ELECTRON-BEAM LITHOGRAPHY SYSTEM AT 50 KEV FOR X-RAY MASK APPLICATIONS

The application of electron beam lithography for the fabrication of x-ray masks is essential in the development of x-ray lithography technology. In this paper we present experimental results on the patterning of submicron (2-0.25-mu-m) features into a single-layer negative e-beam resist and then subsequent transfer of these patterns onto a 0.4-mu-m-thick tungsten film by reactive ion etching. To study the dependence of the proximity effect on the substrate material, a comparison of linewidths and sidewall profiles of electron beam resist images on silicon, silicon dioxide on silicon, and tungsten on silicon wafers has been established.