Resistive Switching Characteristics of Multi-Layer Dielectric Materials at the Nanometer Scale

[[abstract]]本論文以金屬/絕緣層/金屬之MIM結構，研究使用不同製程組合成長多層介電材料，於奈米尺度下觀察電阻式記憶特性之行為。我們所沉積的無機介電材料包括 HfO2、SnO2、TiO2，分別以原子層化學氣相沉積( Atomic layer deposition )或電子槍(E-gun)蒸鍍製程製備。有機介電材料3-氨基丙基三乙氧基矽氧烷(γ-APTES)則使用微波輔助溶液相沉積法( Microwave Solution Phase Deposition )成長。奈米尺度下的電性行為則以原子力顯微鏡(AFM)結合半導體參數分析儀Agilent-4156C於各種限流下量測 I-V 特性曲線。導電之 Pt/Ir 原子力顯微鏡探針與介電層直接接觸做為上電極，底電極則使用Ti。 我們發現僅用電子槍蒸鍍製備單層與雙層介電材料之元件的電阻切換特性很差，然而，加一層 γ-APTES於電子槍蒸鍍系統製備之無機介電材料上，能有效改善電阻切換特性。藉由施加各種不同的順逆向及單雙掃描的電壓並分析其 I-V 曲線，實驗的結果顯示，在我們所有研究的電阻式記憶體元件其 I-V 曲線特性皆為雙極性。其中PtIr/γ-APTES/E-gun-SnO2/Ti結構在本論文所有的研究元件中，表現最佳的雙極性電阻切換特性，我們推測γ-APTES中富含氧空缺與不同介電材料間之界面應力主導電阻切換特性。[[abstract]]In this thesis, memristive behaviors at the nanometer scale of the Metal/Insulator/Metal (MIM) structures with multi-layer dielectric materials using a combination of different processes were investigated. The inorganic dielectric materials including HfO2, SnO2, TiO2 were prepared by atomic layer chemical vapor deposition (ALD) or e-gun evaporation. The organic dielectric material of γ-APTES was grown by mircowave-asssited solution phase deposition (MWSPD). Nanoscale current-voltage (I-V) characteristics of the memristors were measured by applying a ramp voltage through the conductive AFM tip in conjunction with a semiconductor parameter analyzer Agilent 4156C at various current compliances. The conductive Pt/Ir AFM tip was placed in direct contact with the dielectric to act as the top electrode, and Ti was used as bottom electrode. We found poor resistive switching properties in the devices with the films prepared only by e-gun evaporation process. However, adding a layer of γ-APTES on the top of inorganic dielectric material prepared by e-gun evaporation could much improve the resistive switching properties of the devices. The organic/inorganic structure of PtIr/γ-APTES/E-gun-SnO2/Ti showed the best bipolar resistive switching characteristics in all the studied devices. Oxygen-vacancy rich in γ-APTES and the strain induced between two dielectric materials were suggested to dominate the resistive switching behaviors.[[note]]碩