Implementing TiO2 as gate dielectric for Ge-channel complementary metal-oxide-semiconductor devices by using HfO2/ GeO2 interlayer

Abstract

The electrical properties of plasma-enhanced atomic-layer-deposited (PE-ALD) TiO2 as gate dielectric were investigated for germanium-channel complementary metal-oxide-semiconductor capacitors by using ultrathin in situ HfO2/GeO2 interlayers. TiO2 grown by PE-ALD exhibited a k value of 50±5. An equivalent oxide thickness of 0.9 nm was obtained for the TiO2 (3 nm)/HfO2 (1.2 nm)/GeO2 (0.7 nm) /Ge capacitor with very low leakage current density of 2× 10-7 A/ cm2 at VFB ±1 V. Capacitance-voltage hysteresis was below 30 mV for the TiO2/HfO 2/GeO2 /Ge capacitors. Relatively low minimum density of interface states, Dit ∼5× 1011 eV-1 cm-2 was obtained, suggesting the potential of HfO2/GeO2 passivation layer for the application of TiO2 as gate dielectric for both p-and n-type Ge channels. © 2010 American Institute of Physics.