CuAl₂ thin films as a low-resistivity interconnect material for advanced semiconductor devices

New interconnect materials that have a low line resistivity are required to address issues associated with the increased resistivity due to the aggressive downscaling of future semiconductor devices. In this work, CuAl₂ thin films are investigated as a potential material for liner- and barrier-free interconnect applications. The results show that CuAl₂ blanket films adhere well to and do not undergo interdiffusion with SiO₂, as well as having a favorable size effect of resistivity. Furthermore, the filling of CuAl₂ in narrow low-k trenches is investigated, and an excellent gap-filling performance is registered. These features suggest that CuAl₂ is a promising alternative to Cu that does not require any additional liner or barrier layers for feature sizes less than 10 nm.