This work investigates the thermal stability and barrier characteristics of two species of silicon carbide dielectric films, a-SiCN with a dielectric constant of 4.9 and a-Sic with a dielectric constant of 3.8. The TDDB lifetime of Cu damascene metallization structure is greatly improved by using a a-SiCNI a-SIC bilayer dielectric stack as the etching stop layer (ESL). This improvement is presumably due to the a -S i c dielectric's lower leakage current, absence of nitridation on Cu surface,

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... better adhesion on Cu as well as OSG intermetal dielectric (IMD), though the a -S i c film has a very slow deposition rate. We believe that the a-SiCNIa-Sic bilayer dielectric is a favorable combination for the ESL because a-SiCN can protect a-Sic from plasma attack during the photoresist stripping.