TiO2/HfO2 Bi-layer gate stacks grown by atomic layer deposition for germanium-based metal-oxide-semiconductor devices using GeO xNy passivation layer

Abstract

Material and electrical properties of TiO2/HfO2 bi-layer gate stacks were investigated for germanium (Ge) based metal-oxide-semiconductor devices. In situ NH3 plasma treatment was employed to passivate the Ge surface and promising performance including low capacitance-voltage hysteresis and interface trap density was achieved. It shows a superior dielectric breakdown voltage (4.2-3.4 V) for the TiO 2/HfO2 bi-layer stacks than HfO2 single layer stack at a similar capacitance equivalent thickness (CET) of 1.6 nm. A minimum CET of 1.4 nm was obtained for capacitors on both p and n-type Ge (100) with a gate leakage current density < 4 × 10-7 A/cm2 at VFB ± 1 V. © 2011 The Electrochemical Society. All rights reserved.