Why Is FE-HfO2 More Suitable Than PZT or SBT for Scaled Nonvolatile 1-T Memory Cell? A Retention Perspective

The limited retention time for single-transistor memory cell based on ferroelectric-gated field-effect-transistor (FeFET) has prevented the commercialization of its nonvolatile memory (NVM) option using the commercially available ferroelectric materials, such as strontium bismuth tantalite (SBT) or lead zirconium titanate (PZT), as the gate dielectric. However, the recent advent of the HfO2-based ferroelectric has demonstrated the strong possibility of meeting the NVM requirement of 10-year retention on aggressively scaled FeFETs. This letter will analyze why the retention for HfO2-based ferroelectric (FE-HfO2) is much longer than its PZT or SBT counterparts, based on the two major retention loss mechanisms: depolarization field and charge trapping.