用氧化鋅記憶元件構成的互補式電阻開關｜國立清華大學博碩士論文庫

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研究生：	張浩翔 Chang, Hao-Hsiang
論文名稱：	用氧化鋅記憶元件構成的互補式電阻開關 Complementary resistive switches based on ZnO memristive devices
指導教授：	甘炯耀 Gan, Jon-Yiew
口試委員:	黃振昌熊昌鉑
學位類別：	碩士 Master
系所名稱：	工學院 - 材料科學工程學系 Materials Science and Engineering
論文出版年：	2012
畢業學年度：	100
語文別：	中文
論文頁數：	67
中文關鍵詞：	互補式電阻開關、氧化鋅
相關次數：	點閱：4 下載：0
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為了增加記憶結構的密度，發展出一種記憶元件的排列方式，稱作被動式交叉陣列 (passive crossbar array)。此陣列擁有極高的組成密度，許多記憶元件都能應用於交叉排列。但採用交叉陣列有一個很大的問題，就是潛通道電流 (Sneak path current)。在讀取特定一個元件的狀態時，會受到鄰近元件的影響，透過潛通道電流，導致讀取上的錯誤，嚴重限制了陣列的尺寸。為了解決潛通道電流的問題，Waser團隊提出互補式電阻開關 (complementary resistive switches ，CRS) 的概念，CRS由兩個雙極性轉換 (bipolar switching)的電阻式記憶體反向串聯而成，藉此解決潛通道電流的問題，並增加交叉陣列的尺寸。
本研究採用室溫製程來製作CRS，以ZnO作為中間的固態電解質，因為ZnO在室溫下就可製成具有柱狀晶結構的薄膜，且具有穩定的電阻轉換特性。我們使用射頻磁控濺鍍法在室溫下製成Ag/ZnO/Pt與Pt/ZnO/W的單顆元件。先量測元件的電性與耐久度 (endurance)，再分別將元件以平行串聯的方式組成CRS，量測兩種CRS的電性與耐久度，並比較彼此的差異。且假設在最差情況下，計算CRS運用於交叉陣列中，交叉陣列可達到多大的尺寸。
從實驗結果可得到三個重要的結論：(一)由於Ag/ZnO/Pt的電阻轉換電壓之變動較Pt/ZnO/W大，將其組成CRS後得到的耐久度也較差。可知單顆元件的轉換電壓如果變動過大，會影響CRS的操作耐久度。 (二) 將CRS應用於交叉陣列中，記憶體的陣列尺寸與單顆元件的高低電阻比有關。Ag/ZnO/Pt的高低電阻比大於Pt/ZnO/W，將其組成CRS後應用於交叉陣列中，能得到較大的陣列尺寸。(三) 由於Pt/ZnO/W使用的電流限制比Ag/ZnO/Pt高，將其組成CRS後得到的最大電流值也較高。可知單顆元件設定的電流限制與組成CRS後的最大電流值有關。

目錄

論文摘要    I
誌謝    Ⅱ
目錄    Ⅲ
圖目錄    Ⅴ
表目錄    Ⅷ
第一章 前言與研究動機    1
第二章 文獻回顧    4
    2.1 電阻式記憶體簡介    4
2.1.1 結構    4
2.1.2 操作方式    4
2.1.3 電致步驟    5
    2.2 電阻的轉換機制    5
2.2.1 CBRAM    6
2.2.2 RRAM    7
2.3記憶元件的陣列    8
2.3.1 主動式陣列    8
2.3.2 被動式交叉陣列    9
2.3.3 計算被動式交叉陣列的尺寸     11
2.4 CRS的結構與特性    13
2.5 CRS的量測與模擬    17
2.5.1 初始化過程    17
2.5.2 狀態轉換速度    19
2.5.3 外加電阻的模擬    21
2.6 以ZnO作為固態電解質製成的電阻式記憶體    22
2.6.1 單極性轉換    22
2.6.2 雙極性轉換    24
2.6.3 單極性轉換與雙極性轉換共存    27
第三章 實驗方法與流程    29
    3.1 元件製作    29
        3.1.1 底電極的製備 (Pt與W)    29
        3.1.2 固態電解質薄膜的製備 (ZnO)    30
        3.1.3 上電極的製備 (Ag與Pt)    30
3.2 薄膜的特性分析    31
        3.2.1 SEM    31
        3.2.2 XRD    31
3.2.3 XPS    32
3.3 單顆元件與CRS的電性量測    32
第四章 實驗結果與討論    34
    4.1 單顆元件的特性介紹    34
        4.1.1 Ag/ZnO/Pt    34
        4.1.2 Pt/ZnO/W    39
    4.2 組成CRS的特性    45
        4.2.1 Ag/ZnO/Pt的CRS    45
        4.2.2 Pt/ZnO/W的CRS    49
4.3 CRS的耐久度與穩定性    52
4.4交叉陣列的尺寸    57
4.5初始化過程    60
第五章 結論    62
參考文獻    63

                                

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