Electrical and reliability performance of atomic layer deposition HfO2 capping layer on porous low dielectric constant materials

This work proposes a new method for improving the characteristics of porous low-k dielectric film by capping it with an HfO₂ film by atomic layer deposition (ALD). Experimental results revealed that capping a porous low-k dielectric film with a ~1.0 nm-thick HfO₂ film increases its dielectric constant from 2.56 to 2.65 because the pores in the surface of the film are sealed by Hf precursors. The leakage current density and reliability of the porous low-k dielectrics are greatly improved. The HfO₂ capping film also increased resistances against Cu diffusion and damage by oxygen plasma. Therefore, this ALD-deposited HfO₂ capping film can be used as a pore-sealing layer and a Cu barrier layer for the porous low-k dielectric film in the future advanced technologies.