Effective electrical passivation of Ge(100) for HfO_2 gate dielectric layers using O_2 plasma

摘要

The O_2 plasma pretreatment was investigated for passivation for HfO_2 high-k Ge metal-oxide-semiconductor devices. With proper in situ O_2 plasma passivation, the capacitance-voltage hysteresis was substantially reduced from ～900 to ～50 mV for the HfO_2/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 × 10~(11) eV ~(-1)cm~(-2). A leakage current density of 1.5 × 10 ~(-7) and 2.1 × 10~(-8) A/cm~2 was obtained for the HfO_2/p-Ge and HfO_2-Ge capacitor with equivalent oxide thickness of 1.8 nm at V_(FB) ± 1 V, respectively.