TDDB reliability improvement of Cu damascene with a bilayer-structured α-SiC:H dielectric barrier

This work investigates the thermal stability and physical and barrier characteristics of two species of amorphous silicon carbide dielectric films: the nitrogen-containing alpha-SiCN film with a dielectric constant of 4.9 and the nitrogen-free alpha-SiC film with a dielectric constant of 3.8. The time-dependent-dielectric-breakdown (TDDB) lifetime of the Cu damascene metallization structure is greatly improved by using an alpha-SiCN/alpha-SiC bilayer dielectric stack as the barrier layer. This improvement is attributed to the lower leakage current of alpha-SiC, absence of nitridation on the Cu surface, and better adhesion of alpha-SiC on Cu and organosilicate glass intermetal dielectric. Although the alpha-SiC film has a very low deposition rate, the alpha-SiCN/alpha-SiC bilayer dielectric is a favorable combination for the barrier layer because alpha-SiCN can protect alpha-SiC from plasma attack, such as O2 plasma attack during photoresist stripping and organosilicate plasma attack during organosilicate glass deposition.