Abstract
High quality La2O3 gate dielectrics were deposited by RF magnetron sputtering with thickness of 8 nm, 15 nm, 19 nm and 35 nm. In this work, transistor characteristics, TDDB and conduction mechanism have been discussed. La2O3 showed excellent electrical properties, such as small equivalent thickness, low leakage current, smooth film surface and no interfacial layer with rapid thermal annealing (RTA) at 500℃. N-channel metal-oxide-semiconductor field effect transistors (MOSFETs) using La2O3 gate oxide were fabricated successfully. The minimum threshold voltage was 0.1V and subthreshold swing is 114 mV/dec. The ION/IOFF ratio is about 105 at VD=0.05V. Since St=2.3(kT/q)[1+(CD+Cit)/Cox], the interface trapped charge density Dit is extracted to be about 3.36x1012 cm-2-eV-1. Field effect electron mobility is about 399cm2/V-s. The dominant conduction mechanism of the Al/La2O3/p-Si metal-lanthanum oxide-semiconductor capacitor is Schottky emission at high temperatures from 450K to 550K. The extracted Al/ La2O3 barrier-height and effective electronic mass in 2.9 nm EOT La2O3 films are about 1.22eV and 0.104m0, respectively. Breakdown voltage distributions, Weibull slope, area-scaling factors, have been investigated for La2O3 gate dielectric. The extracted Weibull slope β for different thicknesses (EOT=2.9 nm, 1.2 nm) of the breakdown distribution is found to be 6.4 and 2.6, respectively. And breakdown mechanism is caused by stress-induced charge traps. Percolation model is proposed to explain La2O3 gate dielectric breakdown for the first time. The estimated ten-year lifetime for a capacitor area of 4x10-4cm2 is projected to be -4.8V.