Improvement of HfO2-based Bipolar Resistive Random Access Memory

• Main Authors: Ke, Meng Hsuan, 柯孟萱
• Other Authors: Lien, Chenhsin
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/67113035360281105921

碩士 === 國立清華大學 === 電子工程研究所 === 102 === The resistive RAM has advantages of simple structure, high density, fast switching speed, low power operation, and reliable retention. Furthermore, some RRAMs are friendly for CMOS integration. Thus, RRAM has a great potential as mainstream memories in the future. In this thesis, TiN/Ti/HfO2/TiN RRAM structure was fabricated and studied. Thin Ti layer was inserted between top electrode and hafnium oxide, which can absorb oxygen atoms from dielectric layer. This Ti layer can greately enhance the performance of the RRAM by serving as an oxygen reservoir to fullfill the supply and demand of oxygen in HfO2 layer. The effects of four experiment structure and process parameters on the performance of RRAM were studied in this thesis: active region size、thickness of dielectric layer、annealing temperature、annealing time. The annealing temperature and time plays an ctitica role in this device fabrication. The layer structure of Resistive RAM device studied in this thesis was TiN/Ti/HfO2/TiN, with Ti thickness of 10 nm and HfO2 thickness of 10 nm. By applying post metal annealing at 500⁰C for 4 minutes, RRAM with low operation voltage (<1V), reliable switching endurance (>10^6cycles), high ON/OFF ratio (>10^2) ,and good retention(>5×10^4s) can be achieved.