由於電阻式隨機存取記憶體(Resistive Random Access Memory, RRAM)展現優異的性能，而被視為是最有可能取代動態隨機存取記憶體(DRAM)及快閃記憶體(Flash memory)的前瞻性記憶體，但因為其電阻轉換機制尚未有明確定論，所以影響元件發展的速度，以及商品化的表現與穩定度。
本實驗利用鉭金屬靶進行反應性射頻磁控濺鍍製備氧化鉭(TaOx)薄膜，做為電阻式記憶體元件的主動層，分別沉積銅(Cu) 、鉑(Pt)及鉭(Ta)上電極，製備 Cu/TaOx/Pt, Pt/TaOx/Pt及Ta/TaOx/Pt三元件，探討上電極材料(Cu、Pt & Ta)對元件電性表現之影響。藉由各元件的電性表現與材料分析，嘗試了解TaOx RRAM的電阻轉換機制。
在材料分析及元件電性量測方面，本實驗利用電子微探儀(EPMA)分析TaOx薄膜的O與Ta之計量比；利用低掠角X光繞射分析儀(GIAXRD)及穿透式電子顯微鏡(TEM)之電子繞射，分析TaOx薄膜的結晶性；利用X光光電子能譜儀(XPS)，分析靠近上電極處與主動層內部的TaOx鍵結型態；最後利用精密半導體參數分析儀(Agilent 4156C)進行RRAM元件電性量測分析。
材料分析結果顯示，TaOx薄膜晶體結構為非晶態，而O/Ta的比值為2.43。而Ta-O鍵結型態分析結果顯示，靠近上電極界面的Ta-O鍵結，會隨上電極材料不同而有所變化。電性分析結果顯示，Pt/TaOx/Pt元件在寫入(Write)之後，元件會維持在低電阻態，而無法進行抹除的動作。Cu/TaOx/Pt元件可以雙極性(正偏壓寫入，負偏壓抹除)操作元件，進行寫入/抹除的動作。藉由統計元件從高電阻態轉換到電阻態的臨界電壓(Vset)，可算出Cu/TaOx/Pt元件之平均臨界電壓為3.00V，臨界電壓標準差為2.02 V，而Cu/TaOx/Pt的元件可運作次數(Endurance)只有20次。在雙極性的運作模式下，Ta/TaOx/Pt元件的的平均臨界電壓為3.70 V，臨界電壓標準差為0.79 V，且其可運作次數測試可達2500次。由元件的臨界電壓標準差以及可運作次數，顯示在雙極性運作下，Ta/TaOx/Pt元件相較於Cu/TaOx/Pt與Pt/TaOx/Pt有較優異的電性表現。

According to the outstanding performances, resistance random access memory (RRAM) is regarding as the excellent substitution for DRAM and Flash memory in the emerging memories. Nevertheless, the development and commercialization of the device are set stuck because of its controversial resistive switching mechanism.
In this research, we deposite tantalum oxide (TaOx) thin films by reactive sputtering from tantalum (Ta) target and deposite copper (Cu), platinum (Pt) and tantalum (Ta) as top electrode to fabricate Cu/TaOx/Pt, Pt/TaOx/Pt and Ta/TaOx/Pt devices. The switching mechanisms are explored base on electrical properties and material characteristics.
Regarding to material characteristics and the electrical properties, the composition of TaOx is determined by Electron probe x-ray microanalyzer (EPMA). The crystal structure of TaOx films are identified by grazing incident angle x-ray diffraction (GIAXRD). X-ray photoelectron spectroscopy (XPS) depth profiling spectra are applied for chemical bonding of TaOx. Finally, the electrical properties of RRAM devices are measure by precision semiconductor parameter analyzer (agilent 4156C).
The material characteristics reveal the TaOx film is amorphous and the O/Ta atomic ratio of TaOx is 2.43. The chemical bonding stae of Ta-O varies with material of top electrode. The electrical properties show that the Pt/TaOx/Pt device keeps at low resistance state (LRS) after writing and can’t erased to high resistance state (HRS). The Cu/TaOx/Pt device can write to LRS and erase to HRS with bipolar operation mode. By gathering statistics of threshold voltage (Vset) form HRS to LRS, the average of Vset of Cu/TaOx/Pt device is 3.00 V, and the standard deviation of Vset is 2.02 V. In addition, its endurance is only twenty times. With biopolar operation mode, the average of Vset and the standard deviation of Vset of Ta/TaOx/Pt device is 3.70 V and 0.79 V. Besides, it has a better endurance which is 2500 times. The sdandard deviation of Vset and endurance show that the Ta/TaOx/Pt has better electrical performance than the other devices with bipolar operation mode.

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