摻雜氧化鋅之三族氮化物電阻式記憶體

Abstract

本文提出了一種新式的電阻式記憶體，與一般使用金屬氧化物製作方式不同。我們利用plasma-enhanced atomic layer deposition (PEALD)生長氮化物及氧化物的薄膜，其中氮化物為的氮化鎵(GaN)以及氮化鋁(AlN)、氧化物為氧化鋅(ZnO)。藉由在Si (100)基板上形成multilayer的結構，接著鍍上銦錫氧化物(ITO)以及電極後測量分析其電性。 本論文主要分為三部分。第一部分為電阻式記憶體元件之製作，包含了電漿輔助型原子層沉積系統(PEALD)的原理與操作、沉積材料成長速率之校正、X射線光電子能譜特性分析，以及元件完整的製程。第二部分為量測系統介紹與各式電流傳導機制的說明，量測系統包含變溫量測以及常溫量測的設置，並做毫秒操作與奈秒操作的比較；電流傳導機制則包含電極-介電質接面電流限制(electrode-dielectric interface limited conduction mechanism)、本體限制(bulk limited conduction mechanism)。第三部分為電阻式記憶體元件之電性量測，包含了分析元件變溫I-V圖形、電阻切換的I-V圖形、電流模型fitting說明、穩定度分析以及奈秒與毫秒脈衝作為元件寫入(Set)與重置(Reset)壽命讀寫次數的量測。 我們用電漿輔助型原子層沉積系統沉積AlN/GaN/ZnO/GaN/AlN (2/2/8/2/2 nm)此種氮化物夾雜氧化物結構，藉由自行撰寫的LabVIEW程式利用GPIB與電腦連結，建立一套完整且自動化的電阻式記憶體量測系統。透過電流fitting分析電阻切換的I-V圖形可以發現利用space charge limited current (SCLC)可以解釋其電阻變化的原因、穩定度分析發現大電阻與小電阻的狀態在10000秒內十分穩定、面積大小會影響單點脈衝操作，故此在大面積時用毫秒脈衝操作可以至少持續10000次；在小面積時用奈秒脈衝操作可以至少持續4000以上。

In this thesis we demonstrate a new device mechanism and material system different from using metal oxide for realizing resistive random access memory (RRAM). We use plasma-enhanced atomic layer deposition (PEALD) to grow nitride films and oxide film. The nitride film are gallium nitride (GaN) and aluminium nitride (AlN) , oxide film is zinc oxide. By growing multilayer on Si (100) substrate by PEALD, sputtering ITO and electrode, we measure and analyze device electrical properties. There are three main parts in this thesis. First, we introduce how to make our memory devices, including the mechanism and operation of PEALD, the calibration of growth rate and X-ray photoelectron spectroscopy analysis of each material, and the whole device fabrication process. Second, we introduce electrical measurement system and the conduction mechanism in dielectric films. The electrical measurement system includes alternating temperature and room temperature and compares millisecond (ms) and nanoseconds (ns) pulses . The conduction mechanisms in dielectric films include electrode-dielectric interface limited conduction mechanism and bulk limited conduction mechanism. Third, we discuss the electrical measurements, including the temperature characteristics of the I-V curves, the resistive switching I-V curves, current fitting, retention analysis , relationship between the set and reset conditions for device life-time cycling test by millisecond (ms) pulse with nanoseconds (ns) pulse. We use PEALD to grow the multilayer structure AlN/GaN/ZnO/GaN/AlN of thickness (2/2/8/2/2 nm), and connect instrument and computer through LabVIEW and GPIB, and then build an automated measurement system for resistive random access memory (RRAM) measurement system. From current fitting, we use the mechanism of space charge limited current (SCLC) to explain resistive switching I-V curves, retention analysis about device can maintain 10000s, resistance on/off ratio of ~ 800, and more than 10000 times operation in millisecond (ms) pulse life-time cycling test for large area, more than 4000 times operation in nanoseconds (ns) pulse life-time cycling test for small area.