Electroless CoWP barrier/protection layer deposition for Cu metallization

A fully encapsulated copper interconnect with CoWP barrier and protection layer can be produced by conformal electroless CoWP barrier layer deposition at the bottom and on the sidewalls of trenches and selective electroless CoWP deposition on in-laid Cu lines. The electroless CoWP deposition is an autocatalytic reaction with activation energy of about 0.985 eV. Deposition rate of about 10 nm/min at 80 degrees C and average surface roughness of 5 nm for 200 nm thick films were measured. CoWP layer with resistivity of 25 mu Ohms.cm was obtained. Resistivity of electroless CoWP films was decreased from 25 mu Ohms.cm to 20 mu Ohms.cm after annealing in vacuum with 10(-7) torr at 400 degrees C for 30 min. The RBS spectra of the Cu/CoWP/Co/Si structure formed by electroless CoWP barrier and Cu deposition and annealed at 400 degrees C for 60 min in vacuum 10(-7) torr showed no interdiffusion in deposited films.