New Insights on device level TDDB at GHz speed in advanced CMOS nodes

Time-dependent dielectric breakdown (TDDB) reliability of advanced CMOS nodes is becoming very challenging. With technology scaling and the hardening of operating conditions requirements, TDDB under static stress (dc) may be insufficient to generate margin-on-device lifetime. The purpose of this paper is to investigate TDDB at circuit operating frequencies. In this respect, ac TDDB experiments are performed and an original test structure is proposed to mimic logical circuit applications up to the gigahertz frequency range. Significant gain is thus demonstrated on both NMOSFETs and PMOSFETs, for both high-K/metal gate and SiO(N)/poly-based technologies. Discussions on the physical mechanisms responsible for ac TDDB dependence are also proposed.