Effects of N2 addition on aluminum alloy etching: optical emission spectroscopy studies

Effects of N₂ addition on the plasma composition activated with `Cl<sub>2</sub>+BCl<sub>3</sub>´ and on the aluminum alloy etching in an inductively coupled plasma source are studied. Optical emission spectroscopy data reveal that admiring small amount of N<sub>2</sub> to the `Cl₂+BCl₃´-plasma generally expedites dissociation processes to increase the density of Cl species within it. The N₂ addition also accelerates the formation of passivation polymers via carbon species, which adhere to the sidewalls of patterned metal lines and protect them against the lateral attacks of deflected diffusive etchants such as Cl species. It seems that the relative abundance of Cl species over the passivation polymers, both which are controlled by the N₂ addition, is a critical factor in determining the sidewall features of patterned metal lines