A stacked hafnium-zirconium oxide multi-bit ferroelectric memory cell and method of fabrication

Abstract

This invention discloses a multi-bit ferroelectric memory cell made of hafnium-zirconium oxide and its fabrication method. The memory cell includes a first electrode and a second electrode, with a multi-state ferroelectric stack disposed between them. The multi-state ferroelectric stack comprises alternating layers of hafnium oxide and zirconium oxide, and the multi-state ferroelectric stack achieves multi-bit information storage through multi-state polarization. The hafnium-zirconium oxide ferroelectric stack (multi-state ferroelectric stack) has stable polymorphisms for storing multi-bit data and can quickly switch between different storage states. The electrode layer provides the electric field driving force while regulating stress and the oxygen vacancy spatial distribution of the electrode-ferroelectric interface layer; it also optimizes the stability of the polarization state and the driving electric field strength of each bit polarization state. This regulation method can optimize lattice stability and polarization stability, improving the rewrite performance and long-term stability of the memory.

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