臺灣博碩士論文加值系統

快閃記體身為非揮發記憶體，強調的是資料的保存，因此可靠度的特性相對非常重要。造成可靠度衰退的原因主要是在寫入與擦拭過程中，有大量的電子必須來回穿隧氧化層，造成氧化層受到傷害越來越嚴重，導致元件的老化而損壞。
在本篇論文中研究嘗試利用漸增式寫入法改善快閃記憶體閘極氧化層受到寫入操作的傷害，結果發現：1.漸增式寫入臨界電壓改變較小但能接受。2.閘極干擾比傳統方波小。3.汲極干擾比傳統方波與自然指數上升波輕微。4.讀取干擾都很微弱以及50、70%的漸增波的讀取干擾較小。5.自然指數上升波形寫入可以有效的減少閘極干擾造成的臨界電壓改變。6.漸增式寫入臨界電壓改變會漸漸降低。7.本篇論文中所使用的寫入操作方式，汲極干擾對臨界電壓的影響皆很大，而且並沒有得到明顯改善。
另外對擦拭法的改進利用二階段擦拭法，也就是在傳統擦拭過程後，加入一次輕微寫入的動作。二階段擦拭對元件的耐力能夠有效的提升，也能夠有效減少閘極干擾對臨界電壓的改變。同時避免過度擦拭造成記憶體陣列漏電的錯誤，可以有效集中擦拭後的臨界電壓分布，這對未來發展有很大的幫助。

第一章 緒論 ………………………………………………………… 1
第二章 快閃記憶體元件操作簡介 ………………………………… 4
2.1寫入與擦拭機制(Program/Erase Mechanisms) …………… 4
2.1.1通道熱電子注入寫入（Channel Hot Electron Injection Programming）…………………………………………………… 4
2.1.2F-N穿隧寫入(Fowler-Nordheim Tunneling Programming) ………………………………………………… 6
2.1.3F-N穿隧擦拭(Fowler-Nordheim Tunneling Erase) … 6
2.2耐力(Endurance) …………………………………………… 7
2.2.1通道熱電子注入寫入 …………………………………… 8
2.2.2 F-N穿隧擦拭……………………………………………… 8
2.3過度擦拭(Overerase) ……………………………………… 10
2.4干擾(Disturbance) ………………………………………… 13
2.5電荷保持 ……………………………………………………… 14
第三章 寫入擦拭操作與量測實驗 ………………………………… 27
3.1閘極耦合參數量測 …………………………………………… 27
3.1.1利用臨界電壓(Threshold Voltage)之量測方式……… 27
3.1.2利用次臨界斜率(Subthreshold Slope)之量測方式… 28
3.1.3利用最大線性傳輸電導(Linear Transconductance)量測方式…………………………………………………………… 29
3.2寫入與擦拭偏壓決定 ………………………………………… 30
3.2.1寫入偏壓決定 …………………………………………… 30
3.2.2擦拭偏壓決定 …………………………………………… 32
3.3閘極漸增式寫入(Ramp Gate Programming) ………………… 32
3.4二階段擦拭（2 Step Erase）…………………………………… 33
3.5電荷汲取法(charge pumping method) ……………………… 34
第四章 實驗結果與討論 …………………………………………… 44
4.1傳統單一方波寫入 …………………………………………… 44
4.1.1傳統單一方波寫入的閘極干擾 ………………………… 44
4.1.2傳統單一方波寫入的汲極干擾 ………………………… 45
4.1.3傳統單一方波寫入的讀取干擾 ………………………… 46
4.1.4傳統單一方波寫入的耐力 ……………………………… 46
4.1.5傳統單一方波寫入的電荷汲取法量測(Charge Pumping Method) ………………………………………………………… 47
4.1.6傳統單一方波寫入對擦拭速度的影響 ………………… 48
4.2漸增式寫入 …………………………………………………… 48
4.2.1漸增式寫入的閘極干擾 ………………………………… 49
4.2.2漸增式寫入的汲極干擾 ………………………………… 50
4.2.3漸增式寫入的讀取干擾 ………………………………… 50
4.2.4漸增式寫入的耐力 ……………………………………… 51
4.2.5漸增式寫入對擦寫速度的影響 ………………………… 52
4.3二階段擦拭 …………………………………………………… 52
4.3.1二階段擦拭的閘極干擾 ………………………………… 53
4.3.2二階段擦拭的汲極干擾 ………………………………… 53
4.3.3二階段擦拭的讀取干擾 ………………………………… 54
4.3.4二階段擦拭的耐力與臨界電壓分布 …………………… 54
4.3.5二階段擦拭法對擦寫速度的影響 ……………………… 55
第五章 結論 ……………………………………………………… 91
參考文獻……………………………………………………………… 92

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