Electrical characterization of high- k gate dielectrics on Ge with HfGeN and GeO 2 interlayers

Abstract

Two kinds of HfSiO x /interlayers (ILs)/Ge gate stack structures with HfGeN- and GeO 2-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 on Ge and changed to HfGeN by N 2 ECR-plasma irradiation, which was used as IL. Another IL was GeO 2, which was grown by thermal oxidation at 500 °C. For dielectrics with HfGeN-IL, PDA of 550 °C resulted in effective oxide thickness (EOT) of 2.2 nm, hysteresis of 0.1 V, and interface state density ( D it) = 7 × 10 12 cm − 2 eV − 1 . For dielectrics with GeO 2-IL, PDA of 500 °C resulted in EOT of 2.8 nm, hysteresis of 0.1 V, and D it = 1 × 10 12 cm − 2 eV − 1 . The structural change of HfSiO x /GeO 2/Ge during the PDA was clarified by using X-ray photoelectron spectroscopy, and the gate stack formation for obtaining the good IL was discussed.