Abstract
AbstractMetal-insulator-semiconductor (MIS) capacitors, n-channel and p-channel metal-oxide-semiconductor (MOS) transistors with HfO2 gate dielectric were fabricated. The HfO2 films were deposited by RF sputtering. The leakage current of MIS capacitors is 0.02 A/cm2 at |VG-VFB| = 1V. Schottky emission is found to be the dominating mechanism at 498 K in the electric field from 1.2 MV/cm to 1.8 MV/cm. The temperature dependence of NMOS transistor characteristics was studied in the temperature range from 300 K to 420 K. The carrier mobility is measured by the split C-V method. The maximum mobility of NMOS transistor is 172 cm2/ V-s while the maximum mobility of PMOS transistor is 16 cm2/ V-s. The mobility degradation mechanism of NMOS transistor was studied. The electron mobility limited by phonon scattering is proportional to T-2.24 at the effective normal field Eeff of 0.5 MV/cm between 300 K and 420 K. The electron mobility limited by surface roughness is proportional to Eeff-0.56 in the fields of 0.5＜Eeff＜1.2 MV/cm at 300 K.The mobility is an important parameter in traditional drift-diffusion theories of MOS transistor, but it is not a well-defined quantity in nanoscale MOS transistors. In this work, the experimental results were compared with the one-flux scattering theory. The backscattering of electrons of NMOS transistor with HfO2 gate dielectric was studied. The backscattering coefficient rc is obtained by measuring the temperature dependence of the drain current. The value of rc is in the range 0.11-0.51 with the gate length varying from 8 μm to 40 μm.