利用陽極電極的調變來改善氧化鉿薄膜之電阻式轉換記憶體其單極操作特性研究

Abstract

這篇論文中，首先我們探討不同限流對電阻式記憶體的影響，然後利用不同的金屬當上電極於氧化鉿/氮化鈦的結構，接著討論電極與各種金屬的功函數和各種金屬的氧化自由能之間的關係。在同樣限流下，可觀察到氧化自由能較低的金屬，沒有電阻式操作的特性，而且氧化自由能較高的金屬，耐操度較差。因為自由能較低的金屬容易在接面處形成金屬氧化物，會導致細絲無法燒斷且不能電阻式操作，而自由能較高的金屬容易在電阻式操作中失去氧離子。因此我們研究用惰性金屬/易反應金屬來當上電極，例如鈀/鋁、鈀/鈦、鉑/鈦等。此種結構具有非常好的電阻式操作的特性，可在高溫下操作，耐久性測試中可轉態超過4000次，資料保存能力可達十年。我們的研究顯示惰性金屬/易反應金屬/氧化鉿/氮化鈦的電阻式記憶體是很有希望被應用在下個世代的非揮發性記憶體。

In this thesis, first, we discuss to influence resistive memory for different compliance current, then the different metals were used as the electrode based on the HfOX/TiN structure. Afterward, we discuss the electrode dependence with various metals work function and free energy of oxidation of various metals. For the same compliance current, lower free energy of oxidation of metals were observed no resistive switching characteristics, and higher free energy of oxidation of metals is bad for endurance test. Because lower free energy of oxidation of metals were easier formed metal oxide at interface, which resulted the filaments were not ruptured and no resistive switching, and higher free energy of oxidation of metals on resistive switching is easier losing oxygen ions. Therefore, we studied with inert metal/reactive metal as top electrode, such as Pd/Al, Pd/Ti, Pt/Ti, and etc. This structure has very good resistive switching characteristics, which could be operated at high temperature, endurance was more than 4000 cycles, and data retention was over ten years. Our study shows that the inert metal/reactive metal/HfOX/TiN resistive memory is a promising candidate for next-generation nonvolatile memory device application.