Ultrathin CVD Cu Seed Layer Formation Using Copper Oxynitride Deposition and Room Temperature Remote Hydrogen Plasma Reduction

Cu seed layers for future interconnects must have conformal step coverage, smooth surface morphology, and strong adhesion. Conformal deposition had been achieved by chemical vapor deposition (CVD), but CVD Cu films have rough surfaces and poor adhesion. In this paper, conformal, smooth, adherent, continuous, and thin Cu films were made by CVD. CuON was deposited from a Cu-amidinate precursor, , and at 140– on Ru. Crystallites in the deposited film have either a or structure depending on the ratio of to . As-deposited CuON films have a smooth surface morphology [ root-mean-square (rms) roughness] and are highly conformal ( step coverage in 40:1 aspect ratio holes). The CuON films were then reduced with remote hydrogen plasma near room temperature to minimize agglomeration of the thin Cu films during reduction. After reduction, CuON films having a crystal structure showed a higher density Cu film than those having a crystal structure . Both reduced Cu films had a smooth morphology ( rms roughness). Thus, deposition of a CuON film having a crystal structure and then reduction with remote hydrogen plasma can make Cu layers that can serve as seed layers of future Cu interconnects.