Analyses of high frequency capacitance-voltage characteristics of metal-ferroelectrics-insulator-silicon structure

Capacitance-voltage (C-V) characteristics of the metal-ferroelectrics-insulator-silicon (MFIS) structure have been calculated by the conventional metal-oxide-silicon (MOS) analysis method. The potential profile is obtained by using the Poisson equation of D-E hysteresis, and its capacitance is estimated as combination of SiO2-Si capacitance and ferroelectric film capacitance obtained fi om dielectric constant corresponding to the internal field. PbZrxTi1-xO3 (PZT) and SrBi2Ta2O9 (SBT) ferroelectrics, SiO2, MgO, SrTiO3 (STO) and CeO2 insulators, and silicon semiconductor, were used as independent parameters for the analyses. The dependence of MFIS C-V characteristics on ferroelectric properties, film thickness and impurity concentration of the semiconductor is calculated. Film thicknesses of ferroelectrics and insulators affect the: memory window width markedly, and have to be optimized in order to obtain a large memory window width. On the other hand, MFIS C-V characteristics and memory window width are not influenced by P-r because the effective P-r is small in the MFIS structure.