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 α-SiCN film with a dielectric constant of 4.9 and the nitrogen-free α-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 α-SiCN/ α-SiC bilayer dielectric stack as the barrier layer. This improvement is attributed to the lower leakage current of α-SiC, absence of nitridation on the Cu surface, and better adhesion of α-SiC on Cu and organosilicate glass intermetal dielectric. Although the α-SiC film has a very low deposition rate, the α-SiCN/α-SiC bilayer dielectric is a favorable combination for the barrier layer because α-SiCN can protect α-SiC from plasma attack, such as O₂ plasma attack during photoresist stripping and organosilicate plasma attack during organosilicate glass deposition.