Dual damascene process for air-gap Cu interconnects using conventional CVD films as sacrificial layers

A dual damascene Cu air-gap interconnect was investigated. To solve issues such as cost and electrical shorts from CMP scratches, a conventional CVD film was used as a sacrificial layer instead of the SOD film that we reported previously. The process integration, electrical characteristics and the TDDB reliability were discussed. The TDDB lifetime was drastically improved, and 4 levels of dual damascene Cu interconnects were successfully fabricated.