Plasma etching of ternary silicide top layers

Plasma etching of epitaxial CoSi 2 films with a ternary Co–Ti–Si top layer formed during solid phase reaction of Co/Ti bilayers on Si(100) was investigated. By using a pure argon-RF-plasma the ternary top layer was sputtered without formation of a disturbing overlayer. The main disadvantage of this process is the formation of a crater-like surface morphology connected with a strong increase of the surface roughness. Etching the ternary top layer by a reactive process (CF 4/Ar) leads to a smoother surface, but a Co–fluoride film was grown on top of the silicide surface. In a following argon etch process this disturbing overlayer can be removed completely, simultaneously the roughness of the etched silicide surface is reduced considerably.