High performance Au/PZT/TiO_xN_y/Si MFIS structure for next generation ferroelectric memory applications

摘要

The Metal-Ferroelectric-Insulator-Semiconductor (MFIS) capacitors with thin 20 nm lead zirconate titanate (PZT) and titanium oxynitride (TiO_xN_y) buffer layer were fabricated by RF magnetron sputtering technique and characterized. TiO_xN_y as a buffer layer deposited for the first time for MFIS application at different thicknesses and fabricated structure was found to exhibit excellent electrical characteristics at 14 nm TiO_xN_y. Memory window of 0.4 V was found at low sweep voltage of ± 3 V which increases to 1.8 V at sweep voltage of ±14 V indicating multilevel data storage. Moreover the fabricated structure possesses low leakage current density of ～4 μA/cm~2 at 36 nm TiO_xN_y which increases to 12 μA/cm~2 at 4 nm TiO_xN_y at 5 V, reasonable limit. Furthermore, the fabricated structure possesses outstanding data retention capability at 14 nm TiO_xN_y; the high and low capacitance becomes constant after few seconds and clearly distinguishable for 1h and 30 min. This shows that proposed MFIS structure is suitable for high performance ferroelectric memory applications.