The failure mechanism of phase change memories

The phase change memory (PCM) is considered a major candidate for next generation memories due to its nonvolatility, fast program access, and low consumption power. However, the yield, density and operation speed of PCM chips are limited by the cell that has the worst performance. To improve the performance and reduce their cost, it is essential to investigate their failure mechanism. This paper presents an overview of the failure mode and failure mechanism of PCMs induced by electrical operation and manufacture processes, focusing on the issues of electro-migration, thermodynamic effects, phase change stress and thermal stress, voltage polarity, crystallization induced segregation, concentration distribution, heater materials, and the manufacture process.