A Study of Effects of Metal Gate Composition on Performance in Advanced n-MOSFETs

This work investigates the effects of HfO 2 layer defects, formed by the Al atoms in the metal gate, on performance and reliability in advanced n-type metal-oxide-semiconductor field-effect transistors (n-MOSFETs) with different Al content in the gate stacks. Many groups have proposed theories (e.g., Si-H bond dissociation, trapped in high- {k} defects and impact ionization) to explain the degradation mechanisms in MOSFETs, with most focusing on the dissociation of the Si-H bond at the Si/SiO 2 interface and the carrier trapping in the high- k layer. However, for multi- {V}_{{\text {th}}} devices, experimental results indicate that the formation of defects by Al atoms in the HfO 2 layer is the main reason for degradation in advanced n-MOSFETs. Therefore, we propose a mechanism to clarify the deterioration in advanced n-MOSFETs with different Al content in the gate stacks, and this mechanism is confirmed by positive bias temperature instability (PBTI), hot carrier instability (HCI), HCI power-law fitting and the gate-induced drain leakage (GIDL) measurement.