Trench Sidewall Elimination Effect on Line-to-Line Leakage Current in Scalable Porous Silica (k= 2.1)/Cu Interconnect Structure

Abstract

The sidewall film in low-k/copper interconnects is generally applied to protect the etched low-k surface. However, the existence of this film will become a critical issue with shrinking device sizes. In this work, using intermetal low-k film consisting of scalable porous silica (k = 2.1), we tried to eliminate the sidewall film by reducing pore size in 140-nm-pitched scalable porous silica/copper interconnects. Sufficient wiring resistance yield and low wiring capacitance were obtained even in the structure without sidewall. The degradation in the line-to-line leakage caused by the upper layer fabrication process was improved by this sidewall elimination. The mechanism of the leakage degradation was explained by the moisture diffusion from the upper layer, which reacted with the damage site generated by the sidewall formation process.

Novel Air-gap Formation Technology Using Ru Barrier Metal for Cu Interconnects with High Reliability and Low Capacitance

“…It is shown that the leakage current is markedly decreased by the formation of air-gaps. This is because the leakage paths, predominantly located at the interface between two dielectric layers, 34) are effectively cut by the air-gap, as illustrated in Fig. 8.…”