Impact of plasma enhanced atomic layer deposited HfO2 buffer layer on the structural, electrical and ferroelectric properties of metal/ferroelectric/insulator/semiconductor gate stack for non-volatile memory applications

Abstract

For the proposed work, electrical and ferroelectric characteristics of metal–ferroelectric–insulator–silicon (MFeIS) and metal–ferroelectric–insulator–metal (MFeIM) capacitor structures with Bi4Ti3O12 (BIT) as the ferroelectric film deposited on HfO2/Si substrate has been investigated. RF sputtering has been used for the deposition of BIT layer on the plasma enhanced atomic layer deposited (PEALD) HfO2/Si substrate. The structural properties like crystallographic phase, grain size with composition and refractive index of the deposited films has been measured using X-ray diffraction, Field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS) and multiple angle ellipsometry. The electrical and ferroelectric properties has been obtained by fabricating metal/ferroelectric/silicon (MFeS), metal/ferroelectric/metal (MFeM), metal/insulator/silicon (MIS), metal/ferroelectric/insulator/silicon (MFeIS) and metal–ferroelectric–insulator–metal (MFeIM) structures and characterizing using keithley 4200 SCS and Precision Premier II ferroelectric tester. Results indicate the improved memory window from 3.3 V in MFeS structure to 6.3 V in MFeIS structure with 10 nm buffer. The MFeIM structure with 10 nm buffer layer shows the maximum remnant polarization of 4.11 μC/cm2 with endurance higher than 1012 read/write cycles and data retention time greater than 10 years.