Effective electrical passivation of Ge(100) for HfO2 gate dielectric layers using O2 plasma

Abstract

The O2 plasma pretreatment was investigated for passivation for HfO2 high-k Ge metal-oxide-semiconductor devices. With proper in situ O2 plasma passivation, the capacitance-voltage hysteresis was substantially reduced from ∼900 to ∼50 mV for the HfO2/Ge gate stacks. Capacitors show well-behaved capacitance-voltage characteristics on both p- and n-type Ge substrates, indicating an efficient electrical passivation of the Ge interface. The interface trap density for both types of Ge substrates after passivation is below 4 × 1011 eV -1cm-2. A leakage current density of 1.5 × 10 -7 and 2.1 × 10-8 A/cm2 was obtained for the HfO2/p-Ge and HfO2/n-Ge capacitor with equivalent oxide thickness of 1.8 nm at VFB ± 1 V, respectively. © 2011 The Electrochemical Society. All rights reserved.