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博碩士論文 etd-0616118-192644 詳細資訊
Title page for etd-0616118-192644
論文名稱
Title
熱載子效應與自熱效應在可撓式p型低溫多晶矽薄膜電晶體之研究分析
Investigation of Hot Carrier Effects and Self-heating Effects on p-type flexible LTPS TFT
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
72
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2018-07-11
繳交日期
Date of Submission
2018-07-16
關鍵字
Keywords
薄膜電晶體、自我加熱效應、低溫多晶矽、負偏壓溫度不穩定性、熱載子效應
Negative-bias temperature instability, NBTI, thin film transistor, self-heating effect, low temperature poly-silicon, LTPS, hot-carrier effect, TFT
統計
Statistics
本論文已被瀏覽 5694 次,被下載 161
The thesis/dissertation has been browsed 5694 times, has been downloaded 161 times.
中文摘要
隨著科技發展進步,低溫多晶矽(LTSP)薄膜電晶體,其元件特性優異的關係,在小型及中型的面板扮演重要的角色。低溫多晶矽與傳統非晶矽顯示器最大差異在於LTPS 不錯的反應速度,且有高亮度、高解析度、低耗電量與輕薄短小等優點。因此未來,低溫多晶矽將會是小尺寸穿戴式顯示器螢幕的主流。
對與元件的可靠度一直都是低溫多晶矽薄膜電晶體的研究重點,電晶體在高電壓、高電流,和照光的環境下操作時,會造成電晶體的電性劣化,特別是熱載子效應(hot-carrier effect)和自我加熱效應(self-heating effect),這些都是操作電晶體時的重要議題。
本論文探討熱載子效應與自熱效應在可撓式p型低溫多晶矽薄膜電晶體之研究分析。元件的尺寸對於利用不同的量測手法,改變元件尺寸及操作頻率,找出在不同操作環境下所造成的劣化情形,進而分析及有效提出解決方法。
第一部分將探討可饒式P型低溫多晶矽薄膜電晶體在熱載子電應力(Hot-carrier Stress, HCS)操作後的異常電性變化並釐清其主導機制。實驗中可發現在小的Channel Width下由熱載子所引起的特性變化主要是由電子注入的關係。由於電子注入,使得元件的有效通道縮短,ION 有上升的情形,C-V提早導通。此外由漏電的平行Shift可進一步驗證元件的特性變化主要是因為HCS操作造成的電子注入。
第二部分將對於元件在自我加熱效應所產生的電性變化作為探討。自我加熱效應會因為元件的Channel Width大小而受影響,在大Width下的電性變化臨界電壓(Vt) 向負方向Shift與IOFF下降,主要是由Self-heating和Hot-carrier effects所貢獻。隨著Width愈大,距離邊界就愈遠,散熱條件差,造成的劣化較明顯。由於是在大電流的操作下,通道內會產生焦耳熱(Joule Heating),在源極端有較強的電場,產生較強的NBTI,降低buffer厚度下,能夠有效的將熱逸散掉。進一步探討不同基板下的自我加熱效應情形,PI基板的導熱係數低於玻璃基板,因此PI基板在自我加熱效應下的劣化情形大於玻璃基板。
Abstract
With the rapid development of science and technology, Low temperature poly-silicon thin film transistor (LTPS TFTs) play an important role in small and medium-sized panels. The biggest difference between LTPS TFTs and Amorphous- silicon TFTs display is that LTPS speed of operation is faster and better. Besides, LTPS have high luminance, high resolution, low power consumption and lightweight and short. Therefore, LTPS will be the mainstream of small-size wearable display in the future.
It pointed out that reliability has been the research emphases of Low-temperature poly-silicon thin film transistor. Under high bias, high current and light illumination operation can cause electrical characteristic degradation. Especially, hot-carrier effects and self-heating effects. These are important issues in practical TFTs operation.
In this paper, we studies hot-carrier effects and self-carrier effect in p-type flexible LTPS TFTs. Using different measurement, changing sizes of devices and different frequency of operation. Finding out the deterioration caused by different operating environments, and to further analyze and bring up solutions.
In the first part, the abnormal electrical characteristics after Hot-carrier Stress in p-type flexible LTPS TFTs is investigated. It was found out the electrical characteristics changes mainly caused by Hot-carrier induced electron trapping in small channel width. The channel of device become shorter is due to electron trapping in oxide layer, and on current rising let C-V transfer earlier. In addition, OFF current decrease can verify the changing characteristics of the device is due to hot-carrier stress induce electron trapping.
In second part is going to investigate self-heating effect cause characteristics changing in device. The self-heating effect is affected by the size of the channel width. After stress, the negative threshold voltage shift and OFF current decreases mainly caused by Self-heating effect and Hot-carrier effect. As the channel width getting lager, the condition of heat dissipation is poor and the distance from border gets further which make the degradation more obviously. Due to the high current operation, the channel will induce Joule heating and electric field during self-heating stress is strong near the source, and the NBTI is induced that descend the thickness of buffer layer which can abstract the heat effectively. By discussing the condition of Self-heating effect at different substrate further, we found out that the heat conductivity of PI is lower than the Glass. Therefore, the deterioration of PI with Self-heating effect is bigger than Glass.
目次 Table of Contents
目錄
審定書 i
論文公開授權書 ii
中文摘要 iii
英文摘要 v
目錄 vii
圖次 ix
表次 xii
第一章 緒論 1
1-1 前言 1
1-2 主動層材料性質與優劣比較 1
1-3 顯示器的操作原理 2
1-4 研究動機 3
第二章 簡介與文獻回顧 7
2-1漏電流 7
2-1-1 漏電流來源 7
2-1-2 元件對於漏電流 7
2-2 熱載子效應 8
2-3自發熱效應 9
2-4小結 10
第三章 元件結構與基本特性 11
3-1元件結構 12
3-2元件基本特性 12
3-2-1電晶體輸出特性曲線與轉換特性曲線 12
3-2-2電容電壓的轉換特性 13
第四章 參數萃取及實驗設備介紹 18
4-1參數萃取 18
4-1-1次臨界擺幅(Subthreshold Swing , S.S.) 17
4-1-2臨界電壓(Threshold Voltage,Vt) 19
4-1-3載子遷移率(Carrier mobility, µ) 20
4-2電性量測分析儀器 21
第五章 熱載子效應對低溫多晶矽薄膜電晶體的電性探討 25
5-1 熱載子效應與異常的電流特性曲線 25
5-2小結 36
第六章 元件於自我加熱效應下的異常電性探討 37
6-1 自我加熱效應與異常的電流特性曲線 37
6-1-1 自我加熱效應所產生的缺陷 42
6-1-2 不同基板下的自我加熱效應 43
6-1-3 改變Buffer的厚度 44
第七章 結論 54
參考文獻(Reference) 56
參考文獻 References
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