Effect of pulse frequency on leveling and resistivity of copper coatings

Abstract

Pulse-and DC-plated copper films on wafers were investigated with respect to their applicability as advanced interconnect materials. Pulse frequency was varied to determine its influence on the topography, grain size, and electrical resistivity of electroplated copper films. Morphology and scanning electron microscopy (SEM) studies were conducted on these samples. Smooth and dense coatings were obtained at the optimal frequency of 100 Hz, which displayed the smallest electrical resistance. The leveling capacity of submicron features was also optimized at this frequency.