The Effect of Inter Layers on the Ferroelectric Undoped HfO₂ Formation

Abstract

In this research, we investigated the effect of Hf inter layer and chemical oxide on Si(100) substrate on the ferroelectric undoped HfO₂ deposition. In case with 1 nm-thick Hf inter layer, equivalent oxide thickness (EOT) was decreased from 6.0 to 4.8 nm for 10 nm-thick HfO₂ with decreasing annealing temperature. In case with 0.5 nm-thick chemical oxide, EOT was decreased from 3.9 to 3.6 nm in MFS diodes for 5 nm-thick HfO₂. The MFSFET was fabricated with 10 nm-thick HfO₂ utilizing Hf inter layer. The subthreshold swing was improved from 240 mV/dec. to 120 mV/dec. and saturation mobility was increased from 70 cm²/(Vs) to 140 cm²/(Vs) by inserting Hf inter layer.