利用後續沉積退火處理來提升雙層氧化物結構之電阻式記憶體轉態特性

Abstract

本論文研究利用後續沉積退火處理與搭配雙層氧化物結構之電阻式記憶體來改善電阻轉換特性。利用在底層氧化物層執行氧氣氛環境下的後續熱退火處理，搭配一層未經退火處理的上層氧化物層形成上電極/上層氧化物/底層氧化物/下電極的結構，來改善電阻轉換特性。藉由利用氧氣氛環境下的退火處理來改善薄膜品質的底層電阻轉態層，搭配沉積未經升溫的上層電阻轉態層於底層電阻轉態層之上，可將電阻轉態區域限制在上層電阻轉態層與底層電阻轉態層的界面中，藉此降低因電阻轉態而消耗的氧離子數目，可大幅提升電阻轉態時的穩定特性。研究結果顯示，本元件經由後續氧氣分退火處理底層電阻轉態層之雙層結構電阻式記憶體，其耐操度測試中的高電阻狀態與低電阻狀態比值，可維持大於10倍的值持續107次的電阻轉換。在資料保久度方面，本元件結構可以在85oC環境與0.3伏特電壓讀取下，非破壞性讀取時間可達10000秒。此外，本實驗研究亦將元件結構中的上、下電極材料互換，並且探討改變不同退火時間與溫度條件下，對電阻轉態特性的影響，經由電性量測結果與材料分析所建立的模型，我們可以得知此類結構比傳統的單層結構有較佳電阻轉換特性。因此，本元件結構可讓電阻式記憶體更符合現今互補式金屬氧化物半導體製程與下世代非揮發性記憶體實現量產的應用。

In this thesis, the improvement of resistive switching characteristics is achieved by using post deposition annealing (PDA) treatment in O2 atmosphere on bottom oxide in bilayer structure. Due to the quality of bottom oxide film can be improved by post deposition annealing in O2 atmosphere, followed deposited a non-PDA treatment upper oxide on it form top electrode/upper oxide/bottom oxide/bottom electrode structure, the region for the formation and rupture of conduction filament can be confined the interfacial layer between upper oxide/bottom oxide. Therefore, the consumption of oxygen ions during resistance switching can be suppressed in the present structure. The present device shows good performance of reliability tests, such as endurance, retention, and non-destructive read out. The resistances ratio of high resistance state and low resistance state can be maintained more than 10 times for more than 107 resistance switching cycles. The non-destructive read out test at 85 oC shows stable resistance states for 104 s at a read voltage of 0.3 V. In addition, exchanged of top and bottom electrode material, and the effects of different annealing conditions on the bilayer structure RRAM for resistive switching characteristics are also investigated in this study. Due to the electrical measurement and materials analysis, the present device shows high performance resistive switching properties than conventional single layer structure. Thus, the present device has a good promising for next generation nonvolatile memory applications