Characterization And Mechanism Of Resistive Random Access Memory In GeSo Material

With the vigorous development of the electron information industry such as the Internet of Things?Io T? and Big Data and also with the fast-changing of 3C products such as smartphone and wearable devices, non-volatile memory?NVM? embraces increasing importance in micro-nano-elecronices. However along with the continuous forward marching of the Moore's Law and the ceaseless shrinking of critical dimension, traditional NVM is facing the extremely difficult to achieve smaller dimension owing to the physical and material limitations. Resistive random access memory?RRAM? is outstanding among the candidates in next-generation NVM family for its simple structure, high integration, fast read/write speed and multi-level storage. Based on this, this research firstly focuses on the investigation of RRAM in Ge SO material. The RRAM devices are fully researched through device fabrication, material analyses, electrical measurement, special method treatment and model establishment. The major contributions are outlined as follows:1. The RRAM devices are fabricated on silicon substrate by common methods in semiconductor industry, including Thermal Oxide, Atomic Layer Deposition?ALD?, Photolithography, Inductively Coupled Plasma Etching?ICPE?, Wet Etching and Sputter. After fabricated, the switching layer is analyzed by XPS and FTIR to obtain the mole fraction and the bonds in it, and the device structure is observed by TEM.2. Based on the common electrical measurement, this research firstly obtained the multilevel resistance states not only by continuously increasing sweep voltage but also by repeating sweeps at a fixed cutoff voltage during both set and reset processes. Reliability tests present a 105 level high endurance and a stable 10⁵ second at 85? retention results.3. This paper presents a low temperature fluid treatment method to improve the property of thin film in semiconductor devices. After treated by supercritical carbon dioxide fluid?SCCO₂?, the leakage current in high resistive state?HRS? was 14 times reduced drastically, and the working stability is also improved. The drastically reduction of leakage current suggests that the low temperature supercritical fluid treatment can be used as an excellent method to improve thin film property in low temperature fabrication devices.4. Experiments under alternating current?AC? pulse train operation have been done, and the multilevel resistance states phenomenon can also be presented. Based on this, the property of gradual resistance states is exploited to demonstrate spike-timing-dependent plasticity learning, one of the most fundamental adaptive learning rules of biological synapses, which suggests the Pt/Ge SO/Ti N structure device's potential for using as an electronic synapse device in future neuromorphic systems.5. Focusing on the electrical measurements combined with the analyses of I-V fitting results,physical models are proposed to clarify the conduction mechanism in devices. At last, the corresponding industrial application of RRAM is demonstrated as an attractive candidate in NVM family.