Electromigration characteristics of CuAl2

Abstract

Intermetallic compounds with good thermal stability and low electrical resistivity have opened up a new field of application as interconnect materials in advanced electronic devices; however, its reliability under operating conditions remains unknown. This study focuses on CuAl 2 intermetallic compound and its electromigration (EM) reliability with reference to the results of Cu pure metal. Characteristic parameters and mechanisms related to EM are investigated, including microstructure damage, drift velocity, activation energy, critical length, and lifetime. The results demonstrate that CuAl 2 has superior EM reliability compared with the conventional Cu interconnect material. • The EM characteristics of CuAl 2 were investigated using Cu as a reference material. • Homogeneous drift of Cu was observed across the entire width of the Cu stripe and irregular voids were observed in CuAl 2 . • The drift velocity of Cu in CuAl 2 was greater by a factor of two than that of Al in CuAl 2 . • The critical length was longest in the TaN-capped CuAl 2 , followed by the uncapped CuAl 2 , and by the TaN-capped Cu. • The EM lifetimes of the capped and the uncapped CuAl 2 were 80 and 10 times greater than those of the capped Cu.