Plasma Etching and Roughening of Thin Polymeric Films: A Fast, Accurate, in situ Method of Surface Roughness Measurement

Abstract

AbstractA method is proposed to measure the root mean square surface roughness (hrms) of thin polymeric films on hard substrates during plasma etching. It utilizes in situ monitoring of the film thickness versus etching time by spectroscopic ellipsometry to extract the height distribution and hrms at the corner point (CP). The CP is the time instant where etching rate starts to gradually drop; it depends on the initial film thickness, and denotes the gradual exposure of the hard substrate to the plasma due to the advancement of the rough etch front. The hrms is found equal to approximately half of the remaining thickness at CP. The method compares well with atomic force microscopy measurements.magnified image