Lam Research Corporation
Cobalt etch back

Abstract:

Methods of etching cobalt on substrates are provided. Some methods involve exposing the substrate to a boron-containing halide gas and an additive, and exposing the substrate to an activation gas and a plasma. Additives improve selectively depositing a thicker layer of a boron-containing halide material on a surface of a mask than on a surface of a metal. Additives include H.sub.2, CH.sub.4, CF.sub.4, NF.sub.3, and Cl.sub.2. Boron-containing halide gases include BCl.sub.3, BBr.sub.3, BF.sub.3, and BI.sub.3. Exposures may be performed in two or more cycles, with variations in durations and/or bias power for each exposure in the two or more cycles.