FeRAM

FeRAM, short for ferroelectric RAM, is a type of non-volatile memory that stores information in the polarization state of a ferroelectric material. Data is stored in a capacitor whose dielectric is a ferroelectric film (for example lead zirconate titanate or hafnium-based ferroelectrics). A 1T-1C cell architecture is common, with the transistor acting as access switch.

Writing applies a voltage to align the polarization to represent a bit; Reading involves sensing the remanent polarization through the access transistor and sense amplifier. In many FRAM implementations, a read operation is destructive, requiring a rewrite of the read data.

FRAM combines non-volatility with high write endurance and low energy per write. Endurance on the order of 10^14 to 10^15 cycles has been reported; access times in the nanosecond to tens of nanoseconds range; retention typically years (often at least 10 years at room temperature). It is non-volatile, retaining data without power.

Compared to Flash, write is faster and more energy-efficient; compared to DRAM, it is non-volatile and has lower leakage.

Densities are lower than Flash and DRAM at similar costs; ferroelectric materials require integration challenges on CMOS; scaling and reliability at higher temperatures; still niche relative to Flash and MRAM.

Used in embedded systems, microcontrollers, wearables, automotive and industrial electronics, where frequent writes and nonvolatility are advantageous and data integrity is important after power loss.

Vendors include Fujitsu and Ramtron (now Microchip) and other players; densities range from kilobits to a few megabits, used as an EEPROM alternative in some applications.