在矽基板及塑膠基板上以室溫製備的二氧化鈦電阻式記憶體

Abstract

近年來，由於非揮發性記憶體的應用與發展受到矚目，加上快閃記憶體的微縮極限，有關新世代非揮發性記憶體的發展呈現百家爭鳴的情形。其中，電阻式非揮發性記憶元件具有低功率消耗、高密度、高操作速度、高耐久性、微縮能力高及非破壞性資料讀取等優點，使其成為新世代非揮發性記憶元件的熱門人選。 在電阻式記憶體元件中，在二氧化鈦中的電阻轉換特性吸引了大量的注意力。這非揮發性記憶體的特性，可以穩定的反覆操作在高電阻與低電阻這兩種狀態。也在此材料上同時發現單極轉換及雙極轉換的電阻切換特性，而這不同的電阻轉換操作模式目前被認為與電阻絲形成時的限流，以及上下電極的特性有關。 在這篇論文中，我們主要針對不同上電極對電性的影響。在同一種二氧化鈦氧化層上，蓋上不同的上電極，就能產生整流與電阻切換的特性。而我們也透過探針座串接的方式，量測到1D1R的電性。同時也探討了溫度的效應對於電阻切換以及傳導機制的關聯性。在我們的實驗中所有的元件都是在室溫下以很精簡的實驗步驟完成。低溫的製程讓我們有機會將其電阻式記憶體應用在軟性基板上。最後我們成功的將電阻式記憶體實現在軟性基板上，並且在彎曲測試中依然保有良好的記憶視窗、操作次數、可靠度。

Recently, nonvolatile memories have attracted a lot of attention because of the significant scale limits faced by flash memories. The extensive studies have been carried out to discover the next-generation nonvolatile memory. The resistive random access memories (RRAMs) have the strengths of low power consumption, high density integration, high speed, high endurance, nondestructive read. Therefore, it has shown the promise to be one of the next-generation nonvolatile memory. TiO2 shows characteristic nonvolatile resistive switching behavior, i.e. reversible switching between a high resistance state (HRS) and a low resistance state (LRS). Both unipolar resistive switching (URS) and bipolar resistive switching (BRS) are observed in TiO2 depending on the compliance current for the electroforming or the characteristics of metal electrodes. In this thesis, we focus on the electrical behavior related to different top electrodes. The same material, TiO2, can be used in rectifying and resistive switching elements with different top electrodes. We demonstrated the one-diode-one-resistor (1D1R) electrical characteristics through the external connection. We also studied the temperature dependence during resistive switching operation and the conducting mechanism in each state. All these devices were fabricated at room temperature by very simple process. The low thermal budget process for diode and RRAM could be utilized in the future flexible memory. Finally, the resistive elements were size implemented on the flexible substrate successfully. The flexible RRAM has good electrical characteristics of large memory window, high endurance and long data retention under bending tests.