Multiple bit operation of MFISFET with Pt/SrBi₂Ta ₂O₉/Y₂O₃/Si gate structure

A single transistor type ferroelectric memory with multiple bit operation was presented. This cell has a metal ferroelectric insulator semiconductor field effect transistor structure. Y₂O₃ thin film was used as a buffer insulating layer to improve the memory characteristics and SrBi ₂Ta₂O₉ was used as a ferroelectric gate material. The multi-level characteristics of four levels with one order of drain current difference were measured according to the writing voltage step of two volt. This multi-level memory cell enables to increase the density of memory in the same space and lower the cost.