Dry development of resists exposed to low-energy focused gallium ion beam

Abstract

This paper proposes a new lithography method employing focused ion beam exposure and subsequent dry development. It is shown that the O2 plasma etching or reactive ion etching rate for resists exposed to gallium ions is much lower than that for resists not exposed. A comparison is made between plasma development and reactive ion development. An improvement in the resist sensitivity and contrast value γ using a CF4+O2 mixture gas for reactive ion development is discussed. It is possible to fabricate 0.5-μm-width lines and spaces in 0.6-μm-thick PMMA film at 1×10−4-C/cm2 gallium ion exposure.