Design of Nonvolatile SRAM with Ferroelectric FETs for Energy-Efficient Backup and Restore

Nonvolatile SRAM (nvSRAM) has emerged as a promising approach to reducing the standby energy consumption by storing the state into an in situ nonvolatile memory element and shutting down the power supply. Existing nvSRAM solutions based on a nonvolatile backup in magnetic tunnel junction and ReRAM, however, are costly in backup and restore energy due to static current. This cost results in a long break-even time (BET) when compared with a lowered voltage standby volatile SRAM. This brief proposes an nvSRAM based on ferroelectric FETs (FeFETs) that are capable of fully avoiding such static current. A simple differential backup and restore circuitry is proposed, achieving sub-fJ/cell total energy per backup and restore operation at the 10-nm node. This leads to hundreds of times BET improvement over existing ReRAM nvSRAM solutions. This nvSRAM also indicates the future FeFET design trends for such memory-logic synergy.