高緻密鎵摻雜氧化鋅奈米柱薄膜應用於全透明高效能電阻式非揮發性記憶體特性

Abstract

近年來隨著消費性電子產品，如：智慧型手機、智慧型平面顯示器、筆記型電腦、MP3 和數位相機等，需求與日俱增，非揮發性記憶體已成為現今半導體工業研發重點之一。其中電阻式記憶體具結構簡單、元件尺寸小、低耗能與操作速度快速等特點，極有可能取代現今主流的快閃式記憶體(Flash Memory)，相當據有潛力成為下世代具三維度立體堆疊結構的高元件密度非揮發性記憶體。為了整合平面顯示器與記憶元件於玻璃基板達到系統面板(system on panel：SOP)的目標，具透明結構的記憶體元件與周邊電路的研究，是非常急迫且重要的課題。 本論文的研究是利用高密度與高次序排列的鎵摻雜氧化鋅奈米柱結構當做電阻轉態層薄膜，搭配ITO電極，做成全透明非揮發性電阻式記憶體元件，主要可分為四個部分。第一部份是調節Ga/Zn的莫爾比例來得到最緻密參數，第二部份則改變奈米線的厚度與改變晶種層的厚度，得到最佳的電特性參數。第三部份為了討論ITO/GZO nanorods/ZnO/ITO結構的轉態機制，我們做了單純奈米線的結構、單純晶種層的結構與晶種層上長奈米線的結構，進而了解奈米線的功用與其特性。其中ITO/GZO nanorods/ZnO/ITO結構據有傑出的電阻轉態特性，其耐操度可達7000次以上並維持大於200倍的高低電阻狀態比值；脈衝導致電阻轉換耐操度部分，在80奈秒的脈衝寬度下，耐操度能超過1000次以上；此外，非破壞性讀取特性顯示，在持續施加一0.3伏特的電壓於上電極，其高低電阻狀態可穩定維持超過105秒；然後，耐久度測試顯示在85℃下，高低電阻狀態可穩定維持超過10000秒。因此，本論文結果顯示，全透明ITO/GZO nanorods/ZnO/ITO的電阻式記憶體結構據有能成為透明電阻式記憶體元件應用的潛力。

Nonvolatile memory (NVM) technology plays a crucial role in the semiconductor industry, due to the rapid progress of portable electronic devices. Nowadays, the mainstream of this technology is flash memory which is based on charge storage and is rapidly reaching its physical limits. Resistive random access memory (RRAM) has several advantages, such as simple structure, low scale of size, low power consumption, fast operation speed and high density. In addition, the transition metal oxides based RRAM is one of the most promising and emerging technologies for future semiconductor applications. On the other hand, the next generation display industry, all of the active elements and peripheral circuit will be fabricated on the same substrate. Therefore, it is important to investigate the transparent electronics to bring the era of system on panel (SOP) technology. In this thesis, the research is focused on the transparent RRAM fabrication with compact GZO nanorods film structure, and it will be described into four parts. Firstly, the modification of Ga/Zn molar ratio in order to get the densest parameter. Secondly, the modification of nanorod and ZnO seeding layer thickness in order to get the best electrical parameter. Thirdly, in order to discuss the switching mechanism of ITO/GZO nanorods/ZnO/ITO structure, pure nanorod structure, pure seeding layer structure, and nanorod add seeding layer structure are fabricated to give extensive understanding about the role of the nanorod and its characteristic. The average transmittances in the present device are large than 80% in the wavelength of visible light region from 400 to 800 nm. A high endurance more than 7000 cycles with the resistance ratios of HRS/LRS about 200 times are achieved in this device. GZO nanorods In addition, the present device shows fast speed operation property (80 ns) and good memory performances, such as good non-destructive read out and retention properties at 85 oC (stable resistance states for more than 105 s). Therefore, the ITO/GZO nanorods/ZnO/ITO device in this study is a good candidate for the transparent RRAM device application.