對於不同溫度條件下的HfZrO與HfAlO鐵電記憶體電容之特性探討

Abstract

近十年來，日常生活中已廣泛使用鐵電材料，由於應用在鐵電材料記憶體(FeRAM)上最多，因此被當成新興技術之非揮發性記憶體之一。此外鐵電閘極場效式電晶體(FeFET)因可高密度整合且不需要額外的記憶電容而備受矚目。鐵電閘極場效式電晶體(FeFET)有著許多優點，如讀寫速度快、操作電壓低、操作次數高…等特性。雖然有著眾多優點，卻無法實際量產，主要原因是傳統常用鐵電材料，如PZT、SBT等有機材料一直無法直接整合於現今CMOS技術上。但近年來的研究發現若是使用二氧化鉿為基底，既能展現出鐵電材料之特性，又是常使用在CMOS技術上的高介電係數材料，且成本遠低於傳統的鐵電材料很多。 在此篇碩士論文中，實現了以氧化鋯鉿為基底結合氧化鋁的鐵電材料電容結構在1150℃退火後會有著不錯的鐵電特性，在正負5V量測到約1.8V的記憶窗(ΔVFB)，且漏電流密度小，透過變溫的量測，記憶窗並不會縮減太多，且和緩衝層有不錯的介面特性。

Decades, ferroelectric materials have been widely used in daily life. About all applications, ferroelectric random access memory (FeRAM) occupies most of ferroelectric materials, so it becomes one of the new-technological nonvolatile memory. Moreover ferroelectric field-effect-transistor (FeFET) does not need supernumerary capacitor and it has high density integration, so it was attracted much attention. Ferroelectric field-effect-transistor (FeFET) has many advantages, such as short program/erase times, low operating voltage, high endurance cycle etc. Even so, mass production still has not been successful up until now. The main problem of FeFET is the traditional ferroelectric materials (e.g. PZT, SBT) which can not be directly integrated into today’s CMOS technology. But recent studies have discovered that HfO2-based thin films can show the characteristics of ferroelectric material. HfO2 is also the material of the high dielectric constant which is widely used in CMOS technology. Compare with traditional ferroelectric materials, the cost is much lower too. In this thesis, we reached the HfO2-based mixed Al2O3 MFIS capacitor have better ferroelectric properties after annealing at 1150℃. The memory window(ΔVFB) of 1.8V is acquired under ±5V operation and lower leakage density. The memory window does not obviously decrease through the variable temperature measurement. In addition, it has good interface characteristics of buffer layer.