Investigation of surface modifications of 193 nm and 248 nm photoresist materials during low-pressure plasma etching

Abstract

Summary form only given. Plasma-based pattern transfer of lithographically produced nanoscale patterns in advanced photoresist materials is often accompanied by photoresist surface roughening and line edge roughening due to factors which are not well understood. We have systematically studied the evolution of surface roughening in prototypical 193 nm and 248 nm photoresist materials during plasma processing using an inductively coupled plasma (ICP) reactor as a function of plasma operating parameters. We used real-time ellipsometry and mass spectrometry, along with atomic force microscopy, X-ray photoemission spectroscopy and time-of-flight secondary ion mass spectrometry in an effort to understand the morphological and chemical changes of the photoresist materials as a function of plasma-surface interactions parameters, e.g. ion flux composition, maximum ion energy, total energy flux, plasma chemistry, and photoresist material. We find a dramatic dependence of surface roughening on the properties of both the plasma process, and the photoresist polymer chemistry, and will describe a mechanistic model of the cause of surface roughening. The presentation concludes with a description of similar studies obtained using a dual frequency (DF) capacitively coupled plasma reactor.