Effect of pH on the CoWP Films Electrodeposited in Alkali-Metal-Free Electrolytes
CoWP films were electrodeposited in alkali-metal-free electrolytes, and the effects of pH of the electrolyte on the
film characteristics such as current density, thickness, composition, and structure were investigated. Larger variation of the
CoWP film composition could be made by changing the pH of electrolyte from 3.5 to 8.5. The films deposited from very acidic
solutions contained larger amounts of tungsten and smaller cobalt. Regardless of pH of the electrolyte, the CoWP film had
amorphous-like structure, indicating that the CoWP film electrodeposited in alkali-metal-free electrolytes could be an
effective capping/barrier layer for copper interconnections.
Index Terms - Alkali-metal-free electrolyte, Barrier layer, CoWP film, Electrodeposition, pH