The correlation of the electrical properties with electron irradiation and constant voltage stress for MIS devices based on high-k double layer (HfTiSiO:N and HfTiO:N) dielectrics

This paper describes the influence of e-beam irradiation and constant voltage stress on the electrical characteristics of metal-insulator-semiconductor structures, with double layer high-k dielectric stacks containing HfriSiO:N and HfTiO:N ultra-thin (1 and 2 nm) films. The changes in the electrical properties were caused by charge trapping phenomena which is similar for e-beam irradiation and voltage stress cases. The current flow mechanism was analyzed on the basis of pre-breakdown, soft-breakdown and post-breakdown current-voltage (J-V) experiments. Based on alpha-V analysis (alpha = d[In(J)]/d[In(V)]) of the J-V characteristics, a non-ideal Schottky diode-like current mechanism with different parameters in various ranges off-V characteristics is established, which limits the current flow in these structures independent of irradiation dose or magnitude of applied voltage during stress. (C) 2009 Elsevier B.V. All rights reserved.