Improved Multibit Storage Reliability by Design of Ferroelectric Modulated Antiferroelectric Memory

In this article, we presented a new concept of ferroelectric (FE) modulated antiferroelectric (AFE) memory with independent two-step state switching and large polarization as a promising option for multibit storage in advanced technology nodes. Based on the Landau–Ginzburg–Devonshire (LGD) theory, four nonvolatile states of AFE with the built-in field can be obtained, and the step-by-step switching among four states was successfully simulated through pulse engineering; then, stable nonvolatile 2-bit storage was experimentally demonstrated in FE/AFE/FE capacitor device, and 0.97-MV/cm bipolar built-in field introduced by FE polarization switching was extracted. The FE + AFE device showed double-peak coercive electric field ( ${E}_{c}$ ) distribution and large remanent polarization ( ${P}_{r}$ ) of $16.9 ~\mu \text{C}$ /cm ² with good process stability. Finally, benefitting from the independently step-by-step switching and large density of effective FE domain, the improved multibit storage reliability was verified by kinetic Monte Carlo (KMC) modeling compared to conventional multibit technology.