Three-dimensional nor memory array of thin-film ferroelectric memory transistors implementing partial polarization

Abstract

A memory structure including three-dimensional NOR memory strings and method of operation is disclosed. In some embodiments, the memory device implements partial polarization to provide a reference signal for read operation. The reference signal realizes a third logical state distinguishable from the first and second logical stages in the ferroelectric memory transistor, such as associated with the program and erase states. In another embodiment, the memory device provides a reference signal for read operation by averaging a first signal associated with a program state and a second signal associated with an erased state of the ferroelectric memory transistor. In some embodiments, the memory device implements one or more partial polarization states to provide a multi-level memory cell with more than one logical bit stored in each memory cell.