Characteristics of Al/SrBi{sub}2Ta{sub}2O{sub}9/HfO{sub}2/Si structure using HfO{sub}2 as buffer layer for ferroelectric-gate field effect transistors

摘要

We have investigated the structural and electrical properties of metal-ferroelectric-insulator-semiconductor capacitors with 280-nm-thick SrBi{sub}2Ta{sub}2O{sub}9 (SBT) ferroelectric films grown on Si as well as on Si with buffer layer (HfO{sub}2). The SBT thin films and HfO{sub}2 buffer layer were fabricated using rf magnetron sputtering method. XRD patterns revealed the formation of well crystallized SBT perovskite thin film on the HfO{sub}2 buffer layer which is evident from sharp peaks in XRD spectra. The electrical properties of the metal-ferroelectric-insulator-semiconductor (MFIS) structure were characterized by varying thickness of the HfO{sub}2 layer. The width of memory window in the capacitance-voltage curves for the MFIS structure decreased with increasing thickness of HfO{sub}2 layer. Leakage current density decreased significantly after inserting HfO{sub}2 buffer layer. This shows that the proposed Al/SrBi{sub}2Ta{sub}2O{sub}9/HfO{sub}2/Si structure ideally suitable for high performance ferroelectric memories.