Influence of Frequency Dependent Time to Breakdown on High-K/Metal Gate Reliability

Abstract

Time-dependent dielectric breakdown and stress-induced leakage current (SILC) behavior of a 28-nm hafnium-based high-k/metal gate n-type MOS transistors are investigated under dc and ac conditions. Compared with the constant voltage stress results under dc conditions, a decrease in device lifetime is observed for low-frequency ac stress. Degradation enhancement and SILC behavior are attributed to defect generation in the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> interface layer. For high-frequency ac stress, a lifetime improvement is observed, because of reduced trap generation.