以濺鍍法製備之鋯酸鍶記憶體元件具有無電壓極性之電阻轉換特性研究

Abstract

近來由各種材料所研製的各種新世代非揮發性記憶元件受到廣泛的注意，其中又以電阻式記憶元件最受囑目，由於其具有雙穩態導電性，可在同一偏壓下表現出兩種不同導電率之特性，並且具有高寫入及讀取速度、非破壞性讀取及結構簡單的優點，將有助於達到高密度積體整合及低操作功率的目的，因此電阻式記憶體儼然成為下一世代非揮發性記憶體之候選人。 本論文利用鈣鈦礦結構材料（鋯酸鍶）作為電阻式記憶體的材料，首先本論文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。在實驗的部分，我們利用射頻磁控濺鍍法製備釩摻雜的鋯酸鍶薄膜作為轉換電阻層，且利用此濺鍍法沉積鎳酸鑭作為幫助鋯酸鍶成長優選方向之緩衝層，底電極白金及頂電極鋁則利用蒸鍍法製備，形成一頂電極/電阻層/緩衝層/底電極的結構，其物理及電學特性我們將於第四章深入探討之，此外我們也將探討元件的記憶體特性，並比較及探討不同元件結構對記憶體特性的影響，更進一步由實驗結果來探討可能的電阻式記憶體的電阻轉換及傳導機制。

Recently, many kinds of next-generation nonvolatile memories, such as resistive random access memory (RRAM) and phase change memory, have attracted a lot of attention. Because of the RRAM possesses the bistable conductivity switching characteristics, the device can exhibit two different conductivities at the same applied voltage. In addition, the RRAM with high operation speed, nondestructive readout, and simple device structure are helpful for high density of integration and lower power consumption. Therefore, the RRAM has been proposed to be a possible candidate of next-generation nonvolatile memories. In this thesis, the RRAM devices manufactured based on SrZrO3 (SZO) thin films are studied and developed. At first, I 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, V2O5 doped SZO film was deposited on the LaNiO3 buffer layer by RF magnetron sputter. Pt and Al act as bottom electrode and top electrode, respectively. Therefore, electrode/resistive thin film/buffer layer/electrode structure is formed. The physical and electrical properties of the device are reported in chapter 4. Besides, the memory effects of the device are also presented, which nearly matches the criteria of RRAM. The resistive switching polarity is also compared the difference with various device structures. Furthermore, the possible resistive switching mechanism based on the research results is also discussed in this thesis.