Distribution analysis and multiple-point tail fitting yield estimation method for STT-MRAM

This paper demonstrates that the read output voltage difference between data and reference voltages in spin-transfer-torque magnetoresistive random access memory is not a single Gaussian distribution but composed of two Gaussian distributions. In addition, a multiple-point tail fitting yield estimation method is proposed to estimate read yield with high accuracy. Monte Carlo HSPICE simulation results, based on industry-compatible 45-nm model parameters, show that the proposed multiple-point tail fitting method improves accuracy by 10x, 4.8x, and 1.9x compared with the normal fitting, importance sampling, and two-point tail fitting methods, respectively.