不同電極對濺鍍法製備之氧化鋁薄膜於電阻式轉換記憶體之研究

Abstract

本論文主要對下一世代非揮發記憶體元件作一簡單介紹，並針對電阻式記憶體元件進行深入的研究。電阻式記憶體元件其原理主要是利用雙穩態電阻值的不同來當作記憶邏輯準位，可應用於非揮發記憶體上。其特性有著高速操作，低功率消耗，和高密度積體整合，除此之外其簡單的金屬-氧化物-金屬三層結構，可符合積體電路製程，低溫成長都是其成為下一世代記憶體的優勢. 在本篇論文內，我們使用射頻磁控濺鍍法來製備氧化鋁薄膜於白金底電極上，並選擇五種不同金屬上電極材料 : 鈦、鎳、鈷、鋁 及 鉑 ，完成金屬上電極 - 氧化鋁 - 鉑之三層結構之電阻式記憶體元件。首先對氧化鋁薄膜進行材料分析，接下來探討此元件的記憶體特性，電學特性和可靠度，並觀察不同上電極材料對氧化鋁薄膜的影響。並由這些分析中歸納出在不同電極下可能的傳導機制和雙穩態電阻值可能的形成原因。相較於其它金屬上電極,當使用鈦金屬為上電極時,記憶元件有著極高的良率、穩定的電阻轉態特性、極性相關及自我限流的轉態特性。並更具新世代非揮發記憶體的應用潛力。

In this thesis, we introduce next-generation nonvolatile memory and focus on resistance random access memory (RRAM) research. The RRAM has bistable resistive switching characteristic which can exhibit two states of different resistance for logic level. Therefore RRAM can be next-generation memory by using this characteristic. Owing to RRAM has excellent characteristics of high-speed operation, low-power, and high-density integration. In addition to its simple cell structure (Metal-oxide-metal tri-layer), CMOS-friendly materials and low process temperature all are advantages for next-generation memory application. RRAM is fabricated with aluminum oxide thin film on Pt bottom electrode by RF magnetron sputter and chose Ti for top electrode. First, we have some material analyses of aluminum oxide thin film. The physical, electrical properties and reliability issue of RRAM would be reported. From those analyses conduction mechanism and switching mechanism could be driven. Compare to other top electrode metals, the memory device has the best device yield, stable bipolar resistive switching performance and self-compliance characteristic by using Ti top electrode. Finally, a solvent is proposed to improve the disadvantage of electrical characteristics for our device. It made the device potential for next-generation memory application.