Spin-transfer torque RAM technology: Review and prospect

Non-volatile RAM (NV-RAM) enables instant-on/off computing, which drastically reduces power consumption. One of the most promising candidates for NV-RAM technology is the spin-transfer torque RAM (SPRAM) based on magnetic tunnel junction (MTJ) device technology. This paper reviews the development of MTJ device technology and formulates considerations regarding its memory application, including SPRAM memory cell structure and operation, write voltage limitation, and thermal stability. At the circuit level, a disruptive read operation for future large integration scale is described. A 4F2 memory cell and a multi-bit cell approach are also presented. Finally, the potential value of instant-on/off computing through NV-RAM and its impact are explored.