鈦上電極對濺鍍法製備之鋯酸鍶薄膜其雙極性電阻轉換特性之研究

Abstract

本論文使用鈣鈦礦結構材料（鋯酸鍶）作為電阻式記憶體的材料。首先將介紹新世代非揮發性記憶體之應用、特性以及優點，本論文中也將探討各種可能的電阻轉換機制及傳導機制。在實驗的部份，我們以射頻磁控濺鍍法去成長鎳酸鑭作為幫助鋯酸鍶成長優選方向之緩衝層，並且利用此濺鍍法製備純鋯酸鍶薄膜作為轉換電阻層，底電極白金及頂電極鈦則利用電子束蒸鍍法製備，形成一頂電極/電阻層/緩衝層/底電極的結構。 一開始，我們將探討不同金屬電極對鋯酸鍶薄膜轉態特性之影響，發現活性鈦金屬電極有助於穩定的電阻轉換特性及增加其續航力和良率。第二部份將鍍有鈦上電極的鋯酸鍶薄膜利用後段熱退火可使元件產生氧化鈦介面層減小其電阻轉換電壓並增強元件的續航力和良率，其中以在攝氏200度進行後段熱退火可使元件有最佳且穩定的電阻轉換特性，同時也比較及探討不同後段熱退火溫度條件對記憶體元件特性的影響，由實驗結果及佐證推測以攝氏200度後段熱退火處理對鈦金屬電極及鋯酸鍶薄膜間所形成之氧化鈦介面層對電阻轉換特性有著最佳的表現。

In this thesis, the RRAM devices manufactured based on SrZrO3 (SZO) thin films are studied and developed. At first, we will introduce the applications, fundamental characteristics, and advantages of next-generation nonvolatile memories. The conduction mechanisms of RRAM that have been published are also discussed. In experimental details, Pure SZO film was deposited on the LaNiO3 buffer layer by RF magnetron sputter. Pt and Ti act as bottom and top electrode by Dual E-Gun evaporation, respectively. Therefore, electrode/resistive thin film/buffer layer/electrode structure is formed. In the beginning, we will discuss the influence of various top-electrode metals for SZO thin film devices. The switching property, endurance and device yield could be stabilized and enhanced by Ti top electrode. Secondly, we use the post metal annealing (PMA) treatment on Ti/SZO structure to generate TiOx interface layer could reduce the operation voltages and also enhance the endurance and device yield of memory device. The SZO memory device with Ti top electrode has the better and stable resistive switching characteristic by PMA at 200℃ for 1 hour. The effects of resistive switching property by different PMA temperatures are also compared and discussed. We conjecture that TiOx interface layer between Ti and SZO film by PMA at 200℃ has good influence on resistive switching property by experiment and proofs.