Electroless Co(Mo,P) films for Cu interconnect application
Thin cobaltmolybdenumphosphorous, Co(Mo,P), films, prepared by electroless deposition, have been studied for barrier and capping layers for copper metallization for ULSI applications. The solutions and the deposition conditions for the preparation of Co(Mo,P) on various seed layers are presented. The material properties of Cu layers with Co(Mo,P) barrier and capping layers, annealed at temperatures up to 350C, were studied by Auger electron spectroscopy (AES) and X-ray photo-emission spectroscopy (XPS). Measuring the resistance of the samples versus time allowed us to study the kinetics of the thin film oxidation. Composition profiling showed that if there is copper diffusion onto either the top capping layer or the bottom barrier layer, it was below the AES system detection level (?0.1%). We conclude that the novel Co(Mo,P) can be used as a barrier against copper diffusion and as an oxidation protection layer.
electroless deposition copper metallization barrier layers