Two kinds of HfSiOx/interlayers (ILs)/Ge gate stack structures with HfGeN- and GeO2-ILs were fabricated using electron cyclotron resonance (ECR) plasma sputtering and the subsequent post deposition annealing (PDA) It was found that HfGe was formed by the deposition of Hf metal oil Ge and changed to HfGeN by N-2 ECR-plasma irradiation. which was used as IL Another IL was GeO2, which was grown by thermal oxidation at 500 degrees C. For dielectrics with HfGeN-IL, PDA of 550 degrees C resulted in effective oxide thickness (EOT) of 2 2 rim, hysteresis of 0.1 V. and interface state density (D-it) = 7 x 10(12) cm(-2) eV(-1) For dielectrics with GeO2-IL. PDA of 500 degrees C resulted in EOT of 2.8 rim. hysteresis of 0 1 V, and D-it = 1 x 10(12) cm(-2) eV(-1) The structural change of HfSiOx/GeO2/Ge during the PDA was clarified by using X-ray photoelectron spectroscopy, and the gate stack formation for obtaining the good IL was discussed Crown Copyright (C) 2009 Published by Elsevier B V All rights reserved.