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研究生：	林培恩 Lin, Pei-En
論文名稱：	雙介電層元件之電容電阻轉換特性與突觸功能 Capacitive-Resistive Switching Characteristics and Synaptic Functions of Double Dielectric Layered Devices
指導教授：	陳貞夙 Chen, Jen-Sue
學位類別：	碩士 Master
系所名稱：	工學院 - 材料科學及工程學系 Department of Materials Science and Engineering
論文出版年：	2021
畢業學年度：	109
語文別：	中文
論文頁數：	130
中文關鍵詞：	非導電燈絲型元件、類神經網路、憶容器、突觸元件
外文關鍵詞：	non-filamentary device, self-rectifying, neural network, memcapacitor
相關次數：	點閱：173 下載：0
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兩端式的阻態轉換記憶體，因其結構簡單(為「金屬-絕緣體-金屬」疊層)，適合搭配電晶體做成 1T1R 陣列結構，被視為具潛力應用於未來類神經網路晶片中作為調整權重的突觸元件。多數的阻態轉換記憶體在初始狀態電流值皆相當低，需要經過一大偏壓形成導電燈絲才能將元件喚醒(forming)，接續的 SET 或 RESET 操作常是伴隨著突升式的上升或下降，這將導致許多突觸性質無法被模擬。吾人在此次研究提出不需經過喚醒過程的Ta/WOx/ZrOx/Pt 元件，具有可以透過電阻值改變與電容值改變來模擬突觸的行為。
第一部分吾人以直流偏壓操作，在未經喚醒的單層 Ta/ZrOx/Pt 元件以正負 4V 偏壓掃幅量測，發現其僅具有微小漏電流，但在插入 WOx 薄膜後，製作出的 Ta/WOx/ZrOx/Pt 元件具有截然不同的電流電壓特性曲線，其阻態轉換為漸進式的，並且須在負偏壓進行 SET 操作，在正偏壓進行 RESET 操作，說明此元件非因形成導電燈絲於介電層中而導致阻態轉換。為了瞭解元件的機制，吾人透過紫外光電子能譜學與參考文獻確定了元件的能帶圖，並且量測 Ta/WOx/ZrOx/Pt 元件在不同掃幅速率的 I-V-t 量測，以及透過更換電極量測電流電壓特性曲線，嘗試分析各層所扮演的角色。
第二部分吾人針對上述元件做電容電壓特性曲線的量測，發現在單層的 Ta/ZrOx/Pt 元件電容電壓特性曲線不具有遲滯行為，但插入 WOx 薄膜後， Ta/WOx/ZrOx/Pt 元件卻產生明顯的遲滯，且電容態也是漸進式的轉換行為。透過電容的量測與導電機制的擬合，可更加證明此元件是非導電燈絲型的元件，而是會受到氧空缺聚集 WOx/ZrOx 界面的濃度多寡影響電性表現。
由於 Ta/WOx/ZrOx/Pt 元件具有漸進式的電阻與電容轉換行為，且在電流電壓與電容電壓特性曲線皆呈現很大的遲滯，吾人在第三部分成功做了一系列透過電流與電容變化來模擬突觸性質，因為兩端式元件需要設置一小的讀取偏壓來讀取電流，相較之下，讀取電容值只需要很小的交流偏壓即可讀取電容值，發展憶容器作為突觸元件，將有利於降低類神經網路電路能秏的產生。

Low power consumption, fast switching speed, and simple structure are the advantages of memristor to become promising memory devices in the future. However, the irreversible electroforming step in the activation of the memristor remains a major obstacle to implementing high-density integration in the crossbar array. This study successfully demonstrates a WOx/ZrOx stack with Ta/Pt electrodes to achieve an electroforming-free Ta/WOx/ZrOx/Pt resistive switching device.
In the I-V curves operated section, Ta/ZrOx/Pt is highly insulating in the initial state and requires a large bias (electroforming step) to set the devices to the operable resistive switching situation. Such highly insulating performance is accomplished by inserting the WOx layer between the top electrode Ta and ZrOx layer. Ta/WOx/ZrOx/Pt device exhibits analog switching without electroforming step and also self-rectifying since the ZrOx/Pt interface creates a Schottky barrier. Furthermore, Ta/WOx/ZrOx/Pt shows a large hysteretic C-V loop instead of a planar capacitor like Ta/ZrOx/Pt shows the constant capacitance during the bias sweep. Through the results of I-V and C-V characteristic, the underlying conductive mechanism is proposed.
Both I-V and C-V characteristic presents the gradual resistive switching performance and a large hysteresis, which allow us to demonstrate the synaptic plasticity via pulse simulation with different amplitude, width, and interval pulse. Then, synaptic functions of potentiation/depression cycles and paired-pulse facilitation (PPF) have been successfully simulated by employed resistance and capacitance as the synaptic weight.

摘要 I
EXTENDED ABSTRACT III
誌謝 VI
目錄 VIII
圖目錄 XI
表目錄 XVII
CHAPTER 1 緒論 1
1-1 前言 1
1-2 研究動機 3
CHAPTER 2 理論基礎與文獻回顧 4
2-1電阻式轉換記憶體(RERAM) 4
2-1-1阻態轉換行為 4
2-1-2阻態轉換機制 7
2-1-3電容效應(Capacitive effect) 17
2-2 突觸元件之行為探討 20
2-3 相關文獻 25
2-3-1 Capacitance-voltage characteristics of organic Schottky diode with and without deep traps 16 25
2-3-2 A new type artificial synapse based on the organic copolymer memcapacitor 14 27
2-4應用 29
CHAPTER 3 實驗方法與步驟 32
3-1實驗材料 32
3-1-1基板 32
3-1-2 基板清洗藥品 32
3-1-3 金屬電極 32
3-1-4 金屬氧化物 33
3-1-5 實驗使用氣氛 34
3-1-6 耗材 34
3-2實驗設備 35
3-2-1乾式熱氧化系統 35
3-2-2 濺鍍系統(Sputter system) 35
3-3 實驗流程 36
3-3-1基板清洗 36
3-3-2 乾式熱氧化成長SiO2 36
3-3-3 清洗已成長SiO2之基板 37
3-3-4 元件製備 37
3-4 分析儀器 38
3-4-1表面粗度儀(-step) 38
3-4-2前瞻聚焦離子束系統(Advanced Focused Ion Beam System，FIB) 38
3-4-3 穿透式電子顯微鏡(Transmission Electron Microscopy，TEM) 39
3-4-4 Ｘ射線光電子能譜儀(X-ray Photoelectron Spectroscopy，XPS) 39
3-4-5 紫外光電子能譜儀(Ultraviolet Photoelectron Spectroscopy，UPS) 40
3-4-6 精密半導體參數分析儀(Precision Semiconductor Parameter Analyzer) 40
CHAPTER 4 結果與討論 41
4-1 元件結構與命名 41
4-2 材料分析與討論 45
4-2-1 TEM 45
4-2-2 XPS 48
4-2-3 UPS 53
4-3 電流電性量測與分析 55
4-3-1單層Ta/WOx/Pt直流電性分析 55
4-3-2單層Ta/ZrOx/Pt直流電性分析 57
4-3-3雙層Ta/WOx/ZrOx/Pt直流電性分析 59
4-3-4主動層WOx在不同厚度下對元件電性之影響 62
4-3-5主動層ZrOx在不同厚度下對元件電性之影響 68
4-3-6主動層ZrOx更換為TaOx對元件電性之影響 72
4-3-7更換不同電極對元件電性之影響 75
4-4 I-V-T不同掃幅速率對元件電性之影響 77
4-5 電容電性量測分析與應用 82
4-6機制探討 90
4-6-1導電機制探討 90
4-6-2電容態轉換機制探討 92
4-6-3不同接面與不同介電層對機制的影響 93
4-7 突觸元件操作 101
4-7-1電容電壓特性曲線 101
4-7-2增益與抑制(Potentiation & Depression) 104
4-7-3成對的脈衝促進(Pair-pulse Facilitation, PPF) 115
4-8文獻比較 122
結論 126
參考文獻 127
                                    

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2026-08-17公開

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