Thermal stress characteristics of Cu interconnects using Air-Gap

Based on the elastic-plastic model, two-dimensional finite element analysis was used to analyze the Air-Gap Cu interconnects thermal stress behaviors. Firstly, the stress evolution with the Air-Gap interconnect formation process steps was studied. Then, two Air-Gap types of Cu interconnects, with Air-Gap in the metal line level or extending to via level, combined with three different dielectrics were modeled to evaluate their stress characteristics. The research result is helpful to understand the influence of the dielectric and Air-Gap structure on the Cu interconnects reliability.