相变存储器失效机理的研究进展

The failure mechanism of phase change memories

相变存储器由于具有非易失性、高速度、低功耗等优点被认为是最有可能成为下一代存储器的主流产品之一。然而存储器芯片的良率、密度和操作速度受制于性能最差的单元，因此研究相变存储器的失效机理对于存储器芯片成本的降低以及性能的提升至关重要。文章综述了相变存储器失效机理的研究进展，主要讨论和归纳了电性操作和工艺制程所导致的相变存储器失效模型和失效机理，包括电迁移、热动力学效应、相变应力和热应力、电压极性、结晶引发的偏析、浓度梯度、电极材料以及制造工艺引起的失效。

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.