Development of Manufacturable Solutions for the Direct Plating of Copper on Robust ALD-Grown Barriers

Abstract

A novel plasma enhanced atomic layer deposition (PEALD)-grown mixed-phase/nano-laminate barrier has been developed which combines the robust barrier properties of TaN with direct plate characteristics of Ru. Preliminary investigation indicates that Ru:TaN layers as thin as 5 nm can be designed to act both as robust copper barrier and as a copper direct plating layer. Direct plated copper films were found to exhibit preferred (111) orientation with the use of medium acid level electrolyte (0.8M H2SO4) and higher plating current density (10 mA/cm2) during the copper electrochemical deposition process. Also, (111) texture in the direct plated copper films improved as Ru content in the mixed-phase barrier was increased. Direct plated copper films were found to possess larger grain size characteristics as compared to copper electroplated on PVD copper seed. The filling characteristics in sub-65 nm features were found to be equivalent for seeded copper and Ru:TaN barrier films without a seed layer.