鎵摻雜氧化鋅奈米柱金屬橋接電阻式記憶體轉態特性之研究

Abstract

Recently, the resistance switching based memory device (RRAM) concept has drawn attention within the scientific community as a potential candidate for non-volatile random access memory. Resistive random access memory has several advantages, such as simple structure, small in size, low power consumption, fast operation speed and high density. In this thesis, the research is focused on Cu based RRAM fabrication with compact GZO nanorods film structure. It will be described in three parts. The first part is Cu/ZnO/ITO structure is fabricated. That device exhibits no switching behavior, because of random diffusion of copper ions. In the second part, Cu/TiW/ZnO/ITO structure is discussed. To control the random diffusion of Cu ions, a TiW barrier layer is fabricated. In the third part, controlling Cu- filament path randomness by GZO nanorods and modification in Ga/Zn molar ratio to get the dense structure for improving the resistive switching characteristics. In this work, 1.5, 2. 2.5and 4% of the Ga/Zn ratio nanorods are used for preparing RRAM. A higher endurance about 10,000 cycles with resistance ratio of HRS/LRS about 400 times are achieved. Therefore, the present device has successfully fabricated and it has a good potential for next generation non- volatile memory application.

電阻式記憶體(RRAM)在非揮發式記憶體的領域已被視為極有淺力的發展項目。電阻式記憶體因其具有簡單結構、元件尺寸小、低功率消耗、高操作速度及高密度之特性，上述特性被視為能夠在未來取代快閃式記憶體成為主流之記憶體應用。 本論文研究的重點為鎵摻雜氧化鋅奈米柱應用於銅電極之電阻式記憶體以改善之轉態特性。主要可分為三個部分。第一部分為Cu/ZnO/ITO結構，此結構因銅離子於氧化鋅導電薄膜之隨機擴散使得此結構不具電阻轉換之特性。第二部分，我們提出Cu/TiW/ZnO/ITO之結構，為了有效的控制銅離子之隨機擴散，加入鈦化鎢(TiW)合金薄膜作為阻擋層。在第三部分，為了提升元件之轉態特性並進一步降低銅燈絲之隨機路徑，加入 了鎵摻雜氧化鋅奈米柱，藉由調整Ga/Zn之莫耳比以形成最緊密之奈米柱。在此實驗提出 1.5、2、2.5及4 % 之Ga/Zn 比例。最後在電性表現上獲得更好的結果，轉態次數可達一萬次以上，且高低阻態電流差距可達400倍，具有極佳的邏輯判別特性。此研究成功的完成具有潛 力的氧化鋅金屬橋接式電阻式記憶體，其良好的電性深具在未來非揮發性記憶體應用的 潛 力。