Boost of orthorhombic population with amorphous SiO2 interfacial layer—a DFT study

Abstract

Abstract Via the density functional theory, the phase diagrams of HZO thin film in MFM (M = TiN, F = HZO) and MFI (I = α-SiO2) structures are constructed with dependences on grain size and temperature. In both MFM and MFI, the region for orthorhombic phase (o-phase) in phase diagram grows when HZO thickness gets thinner. Comparing to MFM, HZO/α-SiO2 interface in MFI suppresses the growth of tetragonal phase (t-phase) to the region of very small grain size ∼1.2 nm. The simulation results agree with the experimental observation by Cheema et al, that the enhanced FE property was obtained in a MFIS (S = silicon) device with ultrathin HZO film (<2 nm). Simulation model indicates more chemical bonds forming between HZO and α-SiO2 interface could stabilize o-phase to greatly enhance the FE property in a MFIS device.