Si etching in high-density SF6 plasmas for microfabrication:: surface roughness formation

Silicon etching and Si surface-roughness formation in high density SF6 plasmas was studied. Etching rates and surface roughness were measured and correlated with ion flux and neutral F atom flux measured in situ. Etching rates are an increasing function of F atom flux, while surface, roughness is not a monotonic function of F atom flux, or the etching rate. In fact, it is shown that one can achieve high etching rates and small surface roughness, a result of great practical importance to MEMS fabrication. Surface roughness increases with time, while scaling analysis of the AFM data shows that in most cases the Si surfaces develop periodic mound structures with a high roughness exponent (similar to0.8) and a small correlation length (similar to80 nm). (C) 2004 Elsevier B.V. All rights reserved.