Study of a Charging Voltage during SiO$_{2}$ Etching in a 2f-CCP

Top-down plasma micro/nano processing is increasingly important for a continuous development of ultra large scale integrated (ULSI) circuits. In particular, etching of contact holes through SiO$_{2}$ film to Si layer is a crucial process for the fabrication of multilayer interconnects. SiO$_{2}$ etching processes of high-aspect-ratio contact hole (HARC) have caused serious problems due to a local charge accumulation inside a deep contact hole, considered as one of the origins of plasma-induced damages. A surface conduction considered as one of possible mechanisms for reducing the charge accumulation at the bottom of a contact hole irradiated to SiO$_{2}$ etching in fluorocarbon gas chemistry is investigated by using both experimental and numerical techniques. The dependence of the charging potential on a biasing voltage obtained by a simulation gives a quite different behavior from that by the experimental result. Under the assumption that the discrepancy is mainly caused by the surface conduction on the sidewall due to C$_{x}$F$_{y}$ polymer deposition, the optimal value of surface conductivity can be estimated.