Integration of ferroelectric BIT and dielectric HfO₂ on silicon substrate with high data retention and endurance for ferroelectric FET applications

Abstract

For this proposed work, the electrical and ferroelectric properties of metal–ferroelectric–insulator–silicon (MFeIS) and metal–ferroelectric–insulator–metal (MFeIM) capacitors with Bi₄Ti₃O₁₂ (BIT) ferroelectric film deposited on HfO₂/Si substrate were investigated. Physical vapor deposition technique (RF sputtering) was carried out for the deposition of 100 nm ferroelectric and high-k dielectric film of 5, 10 and 15 nm thickness. The structural properties such as crystallographic phase, grain size with composition and refractive index of the deposited films were measured by X-ray diffraction, field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS) and multiple angle ellipsometry. Metal/ferroelectric/silicon (MFeS), metal/ferroelectric/metal (MFeM), metal/insulator/silicon (MIS), MFeIS and MFeIM structures were fabricated to obtain the electrical and ferroelectric properties. Investigation shows that the MFeIS structure with 10 nm buffer layer demonstrates improved memory window of 8.81 V as compared to the 3.3 V in the MFeS structure. MFeIM with 10 nm HfO₂ buffer layer shows maximum remnant polarization of 4.05 μC/cm². MFeI (10 nm) S structure even shows endurance higher than 10¹³ read/write cycles and data retention for more than 10 years. The reliability of the ferroelectric and ferroelectric/dielectric stack was obtained by measuring the breakdown voltage characteristics.