A Comprehensive study of reliability improvement for 65nm Cu/Low-k process

BEOL reliability becomes increasing important issues as device dimensions are scaled for the Cu/low-k interconnects, including electromigration (EM), stress migration (SM), inter-line leakage, breakdown and time-dependent dielectric breakdown (TDDB) characteristics of low-k dielectrics, and plasma-process induced damage (P2ID). This paper gives a summary of the BEOL reliability improvement for the 65 nm Cu/low-k process. The efforts for the reliability improvement include process control for metal dimension uniformity, the interface integrity between Cu and cap layer (SiCN), and via bottom integrity; and plasma control for the pre-metal dielectric (PMD) deposition, pre-clean before Cu barrier deposition and passivation etching for Al pad. The corresponding physical mechanisms for the respective improvements will also be discussed.