| Popis: |
Stencil masks for electron-beam projection lithography (EPL), in particular, for low-energy electron beam proximity projection lithography (LEEPL), have been developed using diamond membrane. The diamond membrane gives the masks high rigidity and high thermal conductivity, features which are very effective for obtaining high patterning accuracy. The mask blank is a 4-inch silicon wafer deposited with a diamond film with a thickness of less than 1micrometers . An electron beam mask writer with a 100-kV variable shaped beam is used to form absorber patterns on a hard mask for diamond etching. The diamond is etched by oxygen reactive ion etching to obtain vertical sidewalls. We have successfully fabricated a LEEPL stencil mask with a membrane size of 30 mm x 30 mm, which is larger than a conventional EPL mask. The etched sidewall is very smooth, and we demonstrate 50 to 70-nm line-and-space patterns. |
