Dry development of ion beam exposed PMMA resist

Abstract

The etching characteristics of polymethyl methacrylate (PMMA) exposed to 28Si+ ions and then dry developed by reactive ion etching in an oxygen plasma have been studied. It is shown that etch rates of resists exposed to doses greater than 1×1015 cm−2 (1.6×10−4 C/cm2) at 40 keV are much smaller than those of unexposed resists. A differential etch rate as high as 11 is demonstrated. This property of ion beam inhibited etching (IBIE) has been used to fabricate resist structures with submicrometer features using ’’see-through’’ thin silicon film masks. With further developments of high brightness ion sources, IBIE may be a useful technique to realize high resolution negative tone images in resists.