Distribution of write error rate of spin-transfer-torque magnetoreistive random access memory caused by a distribution of junction parameters

TL;DR

This paper theoretically analyzes how variations in junction parameters affect the distribution of write error rates in STT MRAM, providing analytical formulas and confirming results with simulations to aid reliable device design.

Contribution

It introduces a theoretical framework linking junction parameter distributions to WER distribution, deriving analytical expressions and validating them with numerical simulations.

Findings

WER follows a log-normal distribution due to parameter variability.

Reducing pulse width decreases the coefficient of variation of WER.

Analytical expressions accurately predict WER distribution and statistical measures.

Abstract

Distribution of write error rate (WER) of spin-transfer-torque magnetoreistive random access memory (STT MRAM) caused by a distribution of resistance area product and anisotropy constant is theoretically studied. Assuming that WER is much smaller than unity, and junction parameters obey a normal distribution, we show that the WER obeys a logarithmic normal distribution. We derive analytical expressions for the probability density function and statistical measures. We find that the coefficient of variation of WER can be reduced by decreasing the pulse width. We also perform numerical simulations based on the Fokker-Planck equation and confirm the validity of the analytical expressions. The results are useful for designing reliable STT MRAMs.