Selection of Optimized Materials for CBRAM Based on HT-XRD and Electrical Test Results
Selection of Optimized Materials for CBRAM Based on HT-XRD and Electrical Test Results
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DOI：
10.1149/1.3160570
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发表时间：
2009-09
影响因子：
3.9
通讯作者：
R. Bruchhaus;M. Honal;R. Symanczyk;M. Kund
中科院分区：
文献类型：
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作者：
R. Bruchhaus;M. Honal;R. Symanczyk;M. Kund
在依赖于电阻器的可编程变化的新兴存储器技术中，导电桥接随机存取存储器（CBRAM）由于其在亚20 nm范围内的出色缩放潜力和低功率操作而特别令人感兴趣。该技术利用电化学氧化还原反应在隔离的无定形固体电解质中形成纳米级金属丝。Ge硫属化物是与作为优选金属的Ag组合的高性能固体电解质的候选材料，其显示出高迁移率和开关速度。由于后端线（BEOL）处理的热预算，层堆叠材料必须承受300-450°C范围内的温度。纯GeS在高达450°C下是稳定的，没有结晶。对于GeSe，观察到有害的结晶。采用高温X射线衍射（HT-XRD）和分步退火电学表征方法研究了Ag/GeSe和Ag/GeS材料体系的热稳定性。与Ag/GeSe系统相比，在Ag/GeS系统中用HT-XRD发现的固态反应的较高起始温度是获得更好电性能的关键。即使在峰值温度为300°C的热退火之后，对于硫化物，也实现了存储器元件的超过90%的优异且稳定的成品率，这使得该材料系统适合于低温BEOL工艺。
Among emerging memory technologies that rely on the bistable change of a resistor, the conductive bridging random access memory (CBRAM) is of particular interest due to its excellent scaling potential into the sub-20 nm range and low power operation. This technology utilizes electrochemical redox reactions to form nanoscale metallic filaments in an isolating amorphous solid electrolyte. Ge chalcogenides are candidate materials for high performance solid electrolytes in combination with Ag as the preferred metal showing high mobility and switching speed. Due to the thermal budget for a back end of the line (BEOL) processing, the layer stack materials must withstand temperatures in the range of 300-450°C. Pure GeS was stable up to 450°C without crystallization. For GeSe, deleterious crystallization was observed. High temperature X-ray diffraction (HT-XRD) and electrical characterization with stepwise annealing were applied to characterize the thermal stability of Ag/GeSe and Ag/GeS material systems. The higher onset temperature for solid-state reactions found with HT-XRD in the Ag/GeS system is the key for the better electrical performance compared to the Ag/GeSe system. Even after thermal annealing with a peak temperature of 300°C, excellent and stable yield numbers of more than 90% for memory elements were achieved for the sulfide, which qualifies this material system for a low temperature BEOL process.