Comprehensive understanding of the effect of electric dipole at high-k/SiO2 interface on the flatband voltage shift in metal-oxide-semiconductor device

Abstract

Electrical characteristics of HfO2/SiO2 interface are comprehensively studied to clarify the intrinsic origin of flatband voltage (VFB) shift in metal-oxide-semiconductor (MOS) device with high-k/metal gate structure. A methodology for quantitative extraction of the interface dipole and chargers at high-k/SiO2 interface is proposed. The dipole and charges at HfO2/SiO2 interface are extracted to be about −0.38 V and −1.15×1013 cm−2, respectively. This result shows that the high density of negative charges at HfO2/SiO2 interface rather than the interface dipole are the dominant cause of the positive VFB shift in the MOS device with HfO2/SiO2 stack.