電阻式記憶體新穎材料之開發與機制研究( I )

Abstract

非揮發性記憶體廣泛地使用在可攜式電子產品上。然而隨著記憶體元件尺寸的微縮，傳統浮停閘極(Floating Gate) 結構非揮發性記憶體面臨元件可靠度的問題。許多不同儲存技術的記憶體元件被提出來解決浮停閘極記憶體的問題；其中電阻式記憶體(RRAM)具有結構簡單、讀寫速度快、高密度、低成本、低功率消耗以及非揮發性等優點，極有機會取代NAND Flash以及DRAM記憶體，成為下一世代的非揮發性記憶體，因此受到國內外產業、學術以及研究單位的重視。而RRAM能否產品化的關鍵在於下列幾個要素：1.與IC製程的相容性2.較佳的記憶體特性3.新的應用領域(如平面顯示器)。本計畫基於本實驗室的研究基礎上，將開發最具潛力的RRAM材料，研究內容分成三部份：(1)電阻轉換層材料、(2)電極材料的影響、(3)新領域應用，此外將探討其電阻轉態機制，並藉由機制的釐清，取得改善RRAM特性的關鍵要素。開發電阻式記憶體關鍵材料，以提升國內記憶體產業競爭力，研究架構參考圖一。 (1)電阻轉換層材料 (a)氧化矽/氮化矽之摻雜:一般半導體工業常用的氧化矽及氮化矽不具電阻轉態特性，利用摻雜使不具電阻切換特性的二氧化矽具有電阻轉換特性。 (b) Hihg-K 材料: 篩選與半導體工業製程相容之具潛力RRAM材料，並研究其物理機制。 (2)電極材料的影響:研究不同電極材料，對於電阻轉換特性之影響（包含各種金屬及合金材料），更進一步利用惰性金屬摻雜活性金屬之合金，藉此調整氧儲存層電極的溶氧力，以提升電阻轉換特性。 (3) RRAM的新領域應用:開發全透明RRAM材料，並結合TFT整合在同一面板上，將RRAM記憶體應用在顯示器產業。

Floating gate type nonvolatile memory has been widely applied on portable electrical products. With memory dimension scaling down, the traditional floating gate faces the reliability issues. Many storage approaches are proposed to resolve the scaling problem in the memory. Resistive random-access memory (RRAM) with the advantages of simple structure, fast read/write speed, highly density, lower cost, lower power consumption, and nonvolatile, has attracted research attention in the industry, academy, and research organizations. Therefore, RRAM has a great chance to replace NAND flash and DRAM memories, becoming next generation nonvolatile memory. Three key points to commercialize the RRAM are: (1) compatibility with current IC process, (2) outstanding memory characteristics, (3) application of RRAM in new fields. The physical mechanism of RRAM materials will be also studied. Base on the clarification of mechanism, we can obtain the key point to improve the resistive switching characteristics. Expect to develop the RRAM novel material and enhance the international competitiveness of the domestic memory industry. (1) Resistive switching material: (a) Oxide/nitride doping: The SiO2 and Si3N4 are compatible with the IC process, but the resistive switching behavior does not exist in the SiO2. The resistive switching behavior can be obtained by metal-doped in SiO2 and Si3N4. (b)High-K material: Select the high potential RRAM materials which are compatible with the IC process and investigate the physical mechanism. (2) Influence of electrode material: Investigate the influence of resistive switching behaviors by different electrode material (including various metal and alloy material). (3) New RRAM applications: Develop the transparent ITO/IGZO/ITO resistive memory device and integrated with IGZO TFTs. It can be applied to system-on-panel technology at display industry.