Silicon nitride stencil masks for high resolution ion lithography proximity printing

Masked ion beam lithography using silicon nitride stencil masks at a 25 μm mask-to-sample gap has been used to replicate 80 nm lines and spaces in PMMA. An improved reactive ion etching technique for the silicon-rich silicon nitride (SiNx) mask material using CHF3 at a 500 V self-bias potential is reported. A grid support mask is proposed as a means of exposing arbitrary patterns with a stencil mask. The principle of this technique is demonstrated in the special case of a grating.