High-performance membrane mask for electron projection lithography

A high-performance membrane mask for electron projection lithography (EPL) systems is proposed. The design and material selection of the mask described here were carefully executed by considering not only the lithographic performance but also various properties. The mask described in this article consists of a 600-nm-thick diamond-like carbon (DLC) scatter on a DLC membrane 30–60 nm thick. The optimum thicknesses are obtained by calculating angular distributions of the transmitted electrons by our in-house Monte Carlo simulator. It is expected to have an electron transmission of up to 80% and a beam contrast of 100% with an appropriate limiting aperture. A 1-mm-sq membrane of thickness of down to 30 nm could be successfully prepared. The high-performance membrane mask can obtain high resolution and high throughput of the EPL systems simultaneously.