Charge trapping and detrapping in HfO₂ high-κ gate stacks

Abstract

We report on charge transfer (trapping and detrapping) dynamics in ultrathin poly-Si gated NFET devices with ultrathin HfO2 high-κ gate dielectrics deposited by atomic layer deposition (ALD). The focus of this work is twofold: (i) to investigate the role of processing on charge trapping in the ALD HfO2 stacks and (ii) to study trapped charge (in)stability (i.e., detrapping) as a function of temperature, gate bias and light illumination. The kinetics of both trapping and detrapping suggest the existence of more than one kind of existing traps with their energy levels located deep in the forbidden gap of the insulator. © 2004 Elsevier B.V. All rights reserved.