鐵電記憶體做為前瞻性新形態記憶體，因為其具有較小的操作電壓以及較快的操作速度，有望成為下世代主流的非揮發性記憶體，其中以二氧化鉿作為基底並摻雜其他元素成為目前最常見的鐵電材料。鐵電材料受電場循環下共有三種行為:喚醒、疲勞、極化電流峰分裂效應，其中造成極化電流峰分裂效應的原因為透過施加子循環來使鐵電疇產生分裂現象，進而導致極化量及矯頑電壓的失真，最終影響鐵電元件的可靠度。
本實驗探討不同退火溫度下氧化鉿鋯鐵電電容在部分切換操作下觀察其作為記憶體特性之變化，透過一階反轉曲線來分析不同退火溫度下電容受子循環下的鐵電疇分布情況，並以物性分析為輔助解釋高溫退火下的氧化鉿鋯鐵電層可以免疫於子循環帶來的極化電流峰分裂效應，最後在低溫退火下加入種子層成功抑制該效應。
高溫退火下的氧化鉿鋯在一般操作電壓下呈現較高的極化量和不明顯的喚起效應，歸因於高溫環境提供足夠能量形成較多的正交晶相，但在記憶體的表現上較差的耐久度使其與低溫退火相比形成極大的劣勢。使用部分操作電壓進行子循環可以避免元件崩潰並可以使用較大電壓使其回復，高溫退下的鐵電層在經過相同子循環後因其鐵電籌較不易分裂，故其在記憶體的表現上極化量退化的速度遠比低溫退火來的慢許多。利用非對稱電壓子循環再次驗證，造成極化電流峰分裂效應的原因為操作在子循環下造成的，並與施加對稱電壓子循環結果相同，高溫退火的氧化鉿鋯鐵電電容將較不會受到子循環帶來的負面效果。最後提出疊加種子層可以有效減少極化電流峰分裂的產生，使該結構之鐵電電容得以應用至後段製程上。

As an emerging memory, ferroelectric memory is expected to become the mainstream non-volatile memory for the next generation because of its smaller operating voltage and faster speed. HfO2-based ferroelectric materials become the most common at present. There are three behaviors of ferroelectric materials under the electric field cycles: wake-up, fatigue and split-up effect, among which the reason for the split-up effect is that the ferroelectric domains split by applying sub-cycles. Split-up effect leads to decreasing of polarization and distortion of the coercive field, which will affect the reliability of the ferroelectric memory ultimately.
In this experiment, the characteristics of HZO ferroelectric capacitors with different annealing temperatures were observed under partial switching operation. FORC measurement was used to analyze the ferroelectric domain distribution of capacitors, and the analysis of physical properties is used as an aid to explain that HZO annealed at high temperature can be immune to the split-up effect caused by sub-cycles. Finally, adding seed layers annealing at low temperature successfully suppresses this effect.
HZO annealed at high temperature shows higher polarization and less obvious wake-up effect, which is attributed to more orthorhombic phase. However, poor endurance makes it a disadvantage compared to annealed at low temperature. HZO operating at partial switching voltage can avoid breakdown and can be recovered by applying higher voltage cycles. Ferroelectric domains annealed at high temperature are less likely to split after sub-cycling, so the rate of polarization degradation is much slower than that annealed at low temperature. The asymmetric sub-cycle is also used to verify that the reason for the split-up effect and the results are the same as the symmetrical one. HZO annealed at high temperature would show less negative effects from sub-cycles. Finally, it is proposed that applying seed layers with low annealing temperature can effectively suppress split-up effect, so that HZO with this structure can be applied to the back-end of line.

摘要-i
Abstract-ii
誌謝-iv
目錄-vi
圖目錄-viii
第一章 緒論-1
1-1 前瞻非揮發性記憶體-1
1-1-1 電阻式隨機儲存記憶體-1
1-1-2 磁阻式隨機儲存記憶體-2
1-1-3 相變化隨機儲存記憶體-3
1-1-4 鐵電記憶體-4
1-2 鐵電材料-6
1-2-1 鐵電性-6
1-2-2 鐵電材料發展-7
1-2-3 氧化鉿鋯鐵電薄膜(FE-HZO)-8
第二章 文獻回顧-17
2-1 鐵電材料受電場循環之行為-17
2-1-1 氧空缺產生-17
2-1-2 喚起和疲勞效應-18
2-1-3 極化電流峰分裂效應-21
2-2 鐵電元件在不同條件下子循環的效應和應用-25
2-2-1 鐵電薄膜受不同頻率子循環的行為-25
2-2-2 不同溫度下鐵電薄膜受子循環的行為-26
2-2-3 鐵電元件使用部分切換操作電壓之應用-26
第三章 實驗動機及流程-42
3-1 實驗動機-42
3-2 實驗詳細流程-43
第四章 實驗結果與討論-45
4-1 元件基本特性-45
4-1-1 速度測試-45
4-1-2 P-V圖與耐久度測試-45
4-2 對稱電壓子循環對不同退火溫度之HZO的影響-47
4-2-1 施加波型及P-V圖-47
4-2-2 子循環下之耐久度測試-47
4-2-3 對稱電壓子循環下之電壓-電流特性圖-48
4-2-4 FORC分析-48
4-3 非對稱電壓子循環對不同退火溫度HZO的影響-49
4-3-1 量測波型及耐久度測試-49
4-3-2 非對稱電壓子循環下之電壓-電流特性圖-50
4-3-3 非對稱電壓子循環下之FORC分析-51
4-4 元件物性分析和理想模型-52
4-4-1 物性分析-52
4-4-2 理想模型-54
4-5 利用加入種子層來抑制極化電流峰分裂效應-55
結論及未來展望-70
參考資料-71

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