Electrical Characterization of BEOL Plasma-Induced Damage in Bulk FinFET Technology

Abstract

Due to the small size of the transistors affected by plasma-induced damage (PID), the electrical characterization of this effect is challenging. In this paper, dc characteristics, breakdown measurements and charge pumping results are combined to extract information about the impact of PID occurring during BEOL processing in an advanced bulk FinFET technology. The effect of PID is visible on the threshold voltage and the transconductance, but not on the gate current and the subthreshold swing, suggesting that fixed charges are responsible for this degradation rather than trap creation. This is confirmed with time-dependent dielectric breakdown measurements. Nonetheless, charge pumping measurements demonstrate that PID increases the density of traps by a factor 1.78, even though the absolute density of traps remain too low to affect significantly the dc characteristics of the transistors.