A novel test scheme for detecting faulty recall margin cells for 6T-4C FeRAM

This paper proposes a novel test scheme that can detect faulty margin cells in non-volatile 6T-4C FeRAM (six-transistor four-capacitor ferroelectric random access memory). The FeRAM behaves as a non-volatile memory using spontaneous polarization characteristic of the ferroelectric capacitor. The datum is stored as a difference in the polarization direction, and is read out as potential difference of the polarization direction. The proposed test scheme can screen the faulty cells that have smaller recall margins by injecting offset voltage to the memory cell. The proposed scheme is evaluated by Monte Carlo simulations of 16,000 times. The proposed test scheme is possible to detect all fault cells by injecting the offset voltage of 100 mV in a 0.13 μm CMOS process.