Reactive Ion Etching of SiO2 in the Record Gap of Inductive Thin Film Heads

Abstract

A reactive ion etch process which was developed to remove SiO2 over Permalloy in the record gap of inductive thin film heads is described. Etch rates as high as 500 nm/min are easily achieved using C2F6 as the etch gas. The selectivity of the SiO2 etch process to the underlying layer of normalNiFe exceeds 200:1. Exposure of the normalNiFe film to the etch process has no measurable effect on its magnetic properties or surface roughness. The etch rate depends strongly on the power, pressure, and electrode gap, but not on the flow of C2F6 . At low flows, additions of SF6 and Ar to the process reduce the etch rate by reducing the gas residence time and diluting the etch species. At higher flows of SF6 , the etch rate is reduced due to a decrease in the sheath voltage. While additions of He and O2 have more complex effects on the etch rate, no practical increase in the SiO2 etch rate is achieved with either gas.