電阻式記憶體在二氧化矽基底的薄膜上之開關機制的研究

Abstract

電阻式記憶體具備了可微縮化，低功率的消耗，快速操作特性以及穩定的容忍度的這些特點，使得它能夠成為下一世代的記憶體結構。在這篇論文研究中，我們使用二氧化矽參雜稀土金屬，然後去研究這種金屬-介電質-金屬 Pt/SiO2:Gd/TiN 的電阻式記憶體的結構。 在這篇論文裡，我們藉由 XPS，FTIR，TEM，等材料分析系統和安捷倫 B1500 電性測量系統，由X-射線光電子能譜（XPS）觀察到一些氧空缺存在於原始二氧化矽的薄膜層中。我們的元件也可藉由變溫的電性量測方式測得低電阻狀態（LRS）是較屬於金屬的特性而在高電阻狀態下則是偏向半導體類特性機制。我們也可經由容忍度測試以及開關特性的穩定度於高溫狀態下，來探討此類的電阻式記憶體的可靠度，從它的容忍度可達到十萬次的操作下，一樣可以維持穩定的開關特性。 在參雜的氧化層中，我們發現除了bipolar具有多元儲存的特性外，我們在unipolar一樣可以發現改變停止電壓形成的多元儲存性質，我們除了使用變溫量測外，還使用電流機制分析其傳導方式並對它作參數萃取，最後提出其傳導機制的模型來解釋兩種不同的開關行為的差異。 在參雜的結構下再外加一層純二氧化矽層，我們發現在雙層結構下，具有的參雜層可以看成是一個氧儲存槽，而使得它也具有開關切換的特性，使得互補式電阻開關可以出現在我們的雙層結構中，我們可以用它來取代之前發表的雙層串接結構中的互補式特性，

The resistive switching random access memories (RRAMs) possess some advantages of scalability, low power consumption, fast operating speed and stable endurance. The RRAM with these advantages has high potential for next generation memory applications. We use silicon oxide films doped with rare earth metal Gd as the insulator. The switching mechanism and electrical characteristics of Pt/SiO2:Gd/TiN RRAM devices are investigated by material analysis and electrical measurement system. The material characteristic of the thin insulator film were analyzed by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Aglient B1500 was used to measure the electrical properties. Some oxygen vacancies were observed in the pristine DMO film through XPS. The low resistance state (LRS) is metal-like and the high resistance state has semiconductor-like properties. From the electric measurement at different temperatures, we found that the endurance of the RRAM can achieve 105 cycles and its retention time can reach 104 seconds We also found that the doped layer can achieve multilevel for unipolar reset. We compared it with the bipolar multilevel by reset mechanism and current fitting. After current fitting, we extract parameter and set physical model to explain reset behavior for both unipolar and bipolar. In addition, we added a pure oxide layer on top of the doped layer. We found that the doped layer can act as an oxide reservoir. Because there are two switching layer coexisting complementary resistance switching (CRS) can be made in the double-layer structure. which is simpler in fabrication and can replace a back to back structure.