Abstract
Ferroelectric field effect transistors (FEMFETs) with a metal-ferroelectric -insulator -silicon (MFIS) structure is a promising candidate for non-volatile random access memory because of its high speed, single-device structure, low power consumption, and non-destructive read-out operation. The purpose of the insulator layer is to prevent the reaction and inter-diffusion between the ferroelectric layer and silicon substrate as well as to improve the retention properties. In this work, Dy2O3 and Y2O3 high dielectric constant films were used as the insulator layers. Dy2O3 and Y2O3 have a dielectric constant of 11~13 and 12~18, respectively. They also have good thermal stability with silicon. In this work, metal– ferroelectric-insulator-semiconductor (MFIS) capacitors and field effect transistors with the structures of Al/ Pb (Zr0.53, Ti0.47) O3 (PZT) /Dy2O3/Si and Al/PZT/Y2O3/Si were fabricated. The variation of the memory window as a function of annealing temperatures was studied. The maximum capacitance-voltage (C-V) memory window of Al/PZT/Dy2O3/p-Si capacitors was 2.95V at a sweep voltage of 9 V and was obtained with an annealing temperature of 500℃. The retention times of Al/PZT/Y2O3/Si and Al/PZT/Dy2O3/Si MFISFETs are 11.5 days and 11.1 hours, respectively. The longer retention time of Al/PZT/Y2O3/ Si field effect transistors is attributed to the larger conduction band offset at the Y2O3/Si interface (2.3eV) compared to that of Dy2O3/Si (0.79eV).