Effects of copper seedlayer deposition method for electroplating

Abstract

We have investigated copper seedlayer deposition using both ionized physical vapor deposition (IPVD) and collimation methods by depositing similar films into single and dual damascene structures. Step coverage measurements using transmission electron microscopy indicated that IPVD seedlayers exhibited better bottom and sidewall coverage as compared to collimated seedlayers. Subsequent electroplating of contact structures did not indicate differences in the quality of the filling when observed using scanning electron microscopy (SEM). However electrical testing of 68 000 link dual damascene via chains did show improved chain yield for the IPVD deposited films. Cross sections of the chains revealed small voids at the bottom of some of the vias deposited using collimated seedlayers, while no voiding was observed for the IPVD copper films. Finally SEM examinations of unfilled dual damascene cross sections indicated the IPVD copper seedlayer morphology to be rougher as compared to copper films sputtered using collimation.