物理学报2018，Vol.67Issue(5)：254-261,8.DOI:10.7498/aps.67.20172194
氧分压对Ni/HfOx/TiN阻变存储单元阻变特性的影响
Influneces of different oxygen partial pressures on switching properties of Ni/HfOx/TiN resistive switching devices
摘要
Abstract
The HfOx-based resistive random access memory (RRAM) has been extensively investigated as one of the emerging nonvolatile memory (NVM) candidates due to its excellent memory performance and compatibility with CMOS process. In this study, the influences of deposition ambient, especially the oxygen partial pressure during thin film sputtering, on the resistive switching characteristics are discussed in detail for possible nonvolatile memory applications. The Ni/HfOx/TiN RRAMs are fabricated, and the HfOx films with different oxygen content are deposited by a radio frequency magnetron sputtering at room temperature under different oxygen partial pressures. The oxygen partial pressures in the sputter deposition process are 2％, 4％ and 6％ relative to engineer oxygen content in the HfOx film. Current-voltage (I-V ) measurements, X-ray photoelectron spectroscopy, and atomic force microscopy are performed to explain the possible nature of the stable resistive switching phenomenon. Through the current-voltage measurement, typical resistive switching behavior is observed in Ni/HfOx/TiN device cells. It is found that with the increase of the oxygen partial pressure during the preparation of HfOx films, the stoichiometric ratio of O in the film is improved, the root mean square (RMS) of the surface roughness of the film slightly decreases due to the slower deposition rate under a higher oxygen partial pressure, and the high resistance state (HRS) current decreases. In addition, by controlling the oxygen content of the device, the endurance performance of the device is improved, which reaches up to 103 under a 6％oxygen partial pressure. The HfOx films prepared at a higher oxygen partial pressure supply enough oxygen ions to preserve the switching effect. As the oxygen partial pressure increases, the uniformity of the switching voltage is improved, which can be attributed to the fact that better oxidation prevents the point defects (oxygen vacancies) from aggregating into extended defects. Through the linear fitting and temperature test, it is found that the conduction mechanism of Ni/HfOx/TiN RRAM device cells in low resistance state is an ohmic conduction mechanism, while in high resistance state it is a Schottky emission mechanism. The interface between TE and the oxide layer (HfOx) is expected to influence the resistive switching phenomenon. The activation energy of the device is investigated based on the Arrhenius plots in HRS. A switching model is proposed according to the theory of oxygen vacancy conductive filament. Furthermore, the self-compliance behavior is found and explained.关键词
阻变存储器/氧化铪/氧分压/阻变机理Key words
resistive random access memory/HfOx thin film/oxygen partial pressure/resistive switching mechanism引用本文复制引用
张志超,王芳,吴仕剑,李毅,弭伟,赵金石,张楷亮..氧分压对Ni/HfOx/TiN阻变存储单元阻变特性的影响[J].物理学报,2018,67(5):254-261,8.基金项目
国家重点研发计划(批准号:2017YFB0405600)和天津市自然科学基金(批准号:17JCYBJC16100, 17JCZDJC31700)资助的课题.Project supported by the National Key Research and Development Program of China (Grant No. 2017YFB0405600) and the Tianjin Natural Science Foundation, China (Grant Nos. 17JCYBJC16100, 17JCZDJC31700). （批准号:2017YFB0405600）
