Impact of oxygen annealing on high-k gate stack defects characterized by random telegraph noise

Abstract

The impact of post metal-deposition annealing (PMA) on the trap behavior of high-k/metal-gate metal-oxide-semiconductor field-effect transistors has been studied using drain current random telegraph noise (RTN). The RTN phenomenon is influenced by both trap positions and trap energy, thus corresponding with the PMA passivation mechanism. We found that trap positions in mono-metal-layer annealed (TiN annealed) devices are closer to the TiN/HfO2 interface due to the substitution of nitrogen atoms by oxygen atoms inside the TiN layer. However, replaced nitrogen atoms from TaN can passivate nitrogen defects in TiN that improves device characteristics in dual-metal-layer annealed (TiN/TaN annealed) devices.