Chemically induced defects during copper polish

A high yielding copper damascene process requires defect-free copper surfaces after Cu polish. Critical defects derive from corrosion processes such as pitting corrosion, galvanic corrosion and excess etching. Changes in process conditions for Cu polish as well as the interaction with Ta polish step in a two-step (Cu/Ta) Ta polish can assist in defect reduction. Since these corrosion defects derive from the slurry chemistry itself, their quantities can be significantly reduced but not eliminated with process module changes.