Fabrication of masks for electron-beam projection lithography

Masks for electron projection lithography (EPL) require the use of thin mem branes for either stencil pr all membrane scattering masks. The processes o f forming the printable patterns before or after the membrane etch step are compared for EPL stencil masks. Image size uniformity and image placement distortions are characterized and indicate, with appropriate process optimi zation, either process flow is viable for EPL mask manufacture. Image size uniformity within individual membranes has achieved <10 nm (3<sigma>) with the membrane flow process, and the magnitude of process induced image place ment distortions is similar for both process Rows. Stencil masks have also been fabricated with support rings. The masks with support rings show more repeatable absolute image placement, but the image placement distortion due to patterning is nearly identical for masks with or without a support ring . (C) 2000 American Vacuum Society. [S0734-211X(00)02106-5].