Bi0.5Sb1.5Te3基相变存储器低压低功耗性能优化及相变机理研究

In the electronic system driven by thermoelectric energy or solar energy, it is important to employ memory devices with low threshold voltage and power consumption, that can help to achieve long service time and low cost of production and maintenance. Phase change memory (PCM), with the advantages of simple structure, high operation speed, good compatibility with CMOS technology, has been regarded as a promising candidate for the next generation nonvolatile memory. However, the high-power consumption of PCM has become a performance bottleneck, that limits the application of PCM in the field of low-voltage and low-power consuming data storage. It is believed that the high-power consumption of PCM originates from the high energy requirement for the melt-quenching of phase change material, which is the key for data storage, but with issues of high melting energy and low heating efficiency. To solve these issues, doping of Ge, Ti, and Sc, is applied on the phase change material with a low melting temperature, namely Bi0.5Sb1.5Te3. A reduced power for melting will be achieved by weakening the interatomic binding force and reducing the number of atoms in the structure rearrangement. Meanwhile, a high heating efficiency can be achieved through microstructure regulation induced improvement in Joule heating generation and reduction in heat dissipation. Finally, PCM with the low threshold voltage and low power consumption can be achieved, with the phase change mechanism being elucidated. The breakthrough of PCM performance bottleneck is expected, that will promote the application of PCM in the field of Internet of Things, portable medical electronics, etc.

在热电或光伏等微小能量供能的电子系统中，采用低压低功耗存储器件可以提高续航能力，降低维护成本。相变存储器（PCM）具有结构简单、擦写速度快、与CMOS工艺兼容等优点，被认为是下一代非易失性存储器的有力竞争者。然而，操作功耗作为PCM的性能瓶颈，一直居高不下，限制其在低压低功耗领域的应用。研究认为，PCM的功耗主要受相变材料熔化淬火过程的高能耗限制，该过程是实现数据擦写的关键，但是存在材料熔化耗能高、加热效率低的问题。针对这些问题，本项目以Bi0.5Sb1.5Te3基相变材料作为研究对象，通过掺杂Ge、Ti、Sc等元素，从减弱原子间结合力和减少结构重新排布的原子数量两方面出发，降低熔化耗能；同时，通过微结构调控，从提高焦耳热产率和降低热量耗散两方面出发，提高加热效率；最终，实现低压低功耗相变存储并阐明其相变机理，促进PCM性能瓶颈的突破，推动其在物联网、便携式医疗电子等低压低功耗领域的应用。

相变存储器（PCM）具有结构简单、擦写速度快、与CMOS工艺兼容等优点，被认为是下一代非易失性存储器的有力竞争者。然而，操作功耗作为PCM的性能瓶颈，一直居高不下，限制其在低功耗领域的应用，速度不及内存和缓存也限制其应用场景。本项目研究内容主要围绕低功耗高速相变存储器所涉及到的材料进行展开，主要分为三部分：Bi0.5Sb1.5Te3基相变材料；Sc掺杂Bi0.5Sb1.5Te3相变材料；单质Sb相变材料。其中Sc掺杂Bi0.5Sb1.5Te3相变材料低功耗优势突出，操作功耗仅1nJ，单质Sb相变材料操作速度快，仅需242ps，两者性能都达到了国际领先，有利于推动我国低功耗高速存储器开发。