A Study of Resistivity Control for Subtractive Interconnects Using Ruthenium

Ruthenium is a candidate metal to replace copper for BEOL metal interconnects due to its electrical characteristics and direct etch capabilities. Electrical performance is a major consideration for “beyond copper” metals – especially as the line CD approaches 10nm where copper line resistance increases significantly. In this report we show the impacts of liner material and direct metal etching on blanket and patterned wafer resistance, and use supporting physical and chemical analyses to confirm methods from both processes to decrease ruthenium resistivity.