隨著非揮發性記憶體在高密度資料儲存、低功耗電子元件與新興運算架構中的需求逐漸增加，電阻式隨機存取記憶體（resistive random access memory, RRAM）因具有結構簡單、操作電壓低、切換速度快、可微縮性佳及與半導體製程相容等優點，成為次世代非揮發性記憶體的重要候選技術。然而，RRAM 元件仍面臨導電絲形成與斷裂過程不穩定、操作電壓分散、循環耐久性不足及高低阻態分布不均等問題。因此，如何透過材料選擇、氧空缺調控、電極設計與界面工程改善元件穩定性，為本研究之主要探討方向。
本研究製作並分析氧化鋯（ZrO2）與氧化鋁鎵鍺〔GeO2+AGO(5%)〕作為阻變層之非揮發性電阻式記憶體元件。第一部分以 Ag/ZrO2/Pt/Ti 結構為基礎，探討射頻磁控濺鍍過程中不同氧氣流量比例對 ZrO2 薄膜與元件電性之影響。實驗結果顯示，氧氣流量比例會明顯影響氧相關缺陷濃度與阻變行為。其中，10% 氧氣流量比例之元件具有最佳整體表現，可在低於 1 V 的操作電壓下進行雙極性阻變切換，並展現約 1.65 × 104 的高低阻態比值及穩定的循環特性。XPS 分析結果亦顯示，隨著氧氣流量比例增加，Zr-O 鍵結比例上升，而氧空缺相關成分下降，說明氧氣導入可有效調控 ZrO2 薄膜中的氧相關缺陷。進一步之導電機制分析顯示，最佳化 ZrO2 元件在低阻態主要呈現歐姆傳導特性，而在 set 轉換前則可能與空間電荷限制電流傳導行為有關。
第二部分於最佳化之 ZrO2 元件中導入以原子層沉積（ALD）成長之 Al2O3 插入層，以調控界面特性與導電絲形成行為。結果顯示，4 nm Al2O3 插入層可有效改善元件之阻態分布與切換均勻性，使高低阻態比值提升至約 1.98 × 104，並於連續直流循環量測中維持較穩定之記憶窗。此結果顯示適當厚度之 Al2O3 插入層可作為界面調控層，限制導電絲過度成長並提升阻變切換之再現性。然而，當 Al2O3 厚度增加至 6 nm 時，元件需較高形成電壓才能啟動阻變行為，顯示過厚之絕緣層將不利於低功耗操作。
第三部分探討 GeO2+AGO(5%) 複合阻變層於 RRAM 元件中的應用，並以射頻共濺鍍方式調控氧氣流量比例與 GeO2 濺鍍功率。結果顯示，GeO2+AGO(5%) 元件同樣可呈現雙極性阻變特性。在不同氧氣流量條件中，10% 氧氣流量之元件具有最高高低阻態比值，約為 6.8 × 104，並可維持低操作電壓。在 GeO2 濺鍍功率系列中，當 GeO2 與 AGO(5%) 濺鍍功率皆為 20 W 時，元件展現最佳記憶窗，高低阻態比值可達約 1.13 × 105。此結果顯示，氧氣流量比例與 GeO2 濺鍍功率皆為影響 GeO2+AGO(5%) 複合阻變層缺陷分布與導電絲形成的重要製程參數。
綜合上述結果，本研究證實氧氣流量比例、上電極材料、Al2O3 插入層厚度及 GeO2+AGO(5%) 共濺鍍條件皆會顯著影響氧化物 RRAM 元件之阻變特性。透過氧空缺調控、界面工程及複合氧化物阻變層設計，可有效提升元件之記憶窗、操作穩定性與切換均勻性，並為次世代非揮發性記憶體之材料開發與元件設計提供參考依據。

With the increasing demand for high-density data storage, low-power electronic devices, and emerging computing architectures, resistive random access memory (RRAM) has attracted considerable attention as a promising candidate for next-generation non-volatile memory. RRAM offers several advantages, including a simple device structure, low operating voltage, fast switching speed, high scalability, and compatibility with semiconductor fabrication processes. However, its practical application is still limited by unstable conductive filament formation and rupture, dispersed switching voltages, insufficient endurance stability, and nonuniform resistance-state distributions. Therefore, material selection, oxygen vacancy regulation, electrode design, and interface engineering are important approaches for improving the stability and reliability of RRAM devices.
In this thesis, zirconium oxide (ZrO2)-based and aluminum gallium germanium oxide [GeO2+AGO(5%)]-based non-volatile RRAM devices were fabricated and investigated. In the first part, Ag/ZrO2/Pt/Ti devices were prepared to examine the influence of oxygen flow ratio during radio frequency magnetron sputtering on the material properties and electrical characteristics of ZrO2 films. The experimental results show that the oxygen flow ratio significantly affects the oxygen-related defect concentration and resistive switching behavior. Among the investigated conditions, the device deposited at 10% oxygen flow ratio exhibited the best overall performance, including low operating voltages below 1 V, a high-resistance-state to low-resistance-state ratio of approximately 1.65 × 104, and stable bipolar resistive switching behavior. X-ray photoelectron spectroscopy analysis further indicated that the Zr-O bonding component increased while the oxygen vacancy-related component decreased with increasing oxygen flow ratio, confirming that oxygen introduction during sputtering can regulate oxygen-related defects in ZrO2 films. Conduction mechanism analysis suggested that the optimized ZrO2 device exhibited Ohmic conduction in the low-resistance state, while space-charge-limited conduction-related behavior may contribute before the set transition.
In the second part, an aluminum oxide (Al2O3) insertion layer grown by atomic layer deposition was introduced into the optimized ZrO2-based device to modify the interface and regulate conductive filament formation. The results showed that a 4 nm Al2O3 insertion layer effectively improved the resistance-state distribution and switching uniformity. The device with the 4 nm Al2O3 insertion layer exhibited an HRS/LRS ratio of approximately 1.98 × 104 and maintained a stable memory window during consecutive DC switching cycles. This improvement suggests that an appropriately scaled Al2O3 insertion layer can serve as an interfacial regulating layer to suppress excessive filament growth and enhance switching reproducibility. However, when the Al2O3 thickness was increased to 6 nm, a high forming voltage was required to initiate resistive switching, indicating that an excessively thick insulating layer is unfavorable for low-power operation.
In the third part, GeO2+AGO(5%) composite switching layers were investigated using radio frequency co-sputtering. The effects of oxygen flow ratio and GeO2 sputtering power on the resistive switching characteristics were systematically studied. The GeO2+AGO(5%)-based devices also exhibited bipolar resistive switching behavior. In the oxygen flow ratio series, the device deposited at 10% oxygen flow ratio showed the highest HRS/LRS ratio of approximately 6.8 × 104 while maintaining low operating voltages. In the GeO2 sputtering power series, the device fabricated with GeO2 and AGO(5%) sputtering powers of 20 W and 20 W, respectively, exhibited the largest memory window, with an HRS/LRS ratio of approximately 1.13 × 105. These results indicate that both oxygen flow ratio and GeO2 sputtering power are important processing parameters for optimizing the defect distribution and conductive filament behavior of GeO2+AGO(5%) composite switching layers.
Overall, this study demonstrates that the resistive switching characteristics of oxide-based RRAM devices can be effectively modulated through oxygen vacancy regulation, electrode material selection, insertion layer engineering, and co-sputtering process control. The optimized ZrO2-based and GeO2+AGO(5%)-based devices exhibited improved memory windows, low operating voltages, and enhanced switching stability. These findings provide useful guidelines for the design and process optimization of oxide-based RRAM devices for next-generation non-volatile memory applications.

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