Investigation of amorphous Ni–Al–N film as diffusion barrier between Cu and SiO2

Barrier performance of 10 nm-thick Ni–Al–N layer, prepared by magnetron sputtering, in the Cu/Ni–Al–N/SiO2/Si heterostructure, is investigated. It is found that the Ni–Al–N film keeps amorphous and no obvious reactions/interdiffusions are observed after high temperature annealing at temperatures up to 650 °C, indicating that the amorphous Ni–Al–N layer has good barrier performance. Unlike the conventional failure mechanism of a barrier layer resulting from that Cu diffuses into SiO2/Si and reacts with Si to form copper silicides, agglomeration of Cu film in the Cu/Ni–Al–N/SiO2/Si heterostructure happens when the annealing temperature is higher than 700 °C, which is attributed to the dewetting of Cu film with Ni–Al–N during high temperature annealing. Moreover, the activation energy is estimated to be 1.1 eV based on the Kissinger equation.

► Amorphous Ni–Al–N film was investigated as diffusion barrier for Cu metallization. ► The 10 nm-thick Ni–Al–N barrier possesses very good barrier performance up to 650 °C. ► Failure of the Ni–Al–N barrier is ascribed to agglomeration of Cu film. ► The activation energy is estimated based on the Kissinger equation.