Structural stability of tight-pitched damascene interconnects

The impact of cohesive forces in ruthenium (Ru) is studied for tighter interconnect technologies; such forces can result in bending of lines at these pitches. The sensitivity of these forces to process variations such as aspect ratio of lines, trench profiles, and critical dimensions are studied. It is observed that lower aspect ratio and higher dielectric modulus alleviate the effects of these cohesive forces. An ab-initio molecular dynamics model is used to compare behavior of Ru with that of copper. Higher surface energy of Ru potentially contributes to this bending phenomenon.