不同金屬上電極對氧化鋯鉿金屬-氧化物-半導體鐵電電容特性影響

Abstract

近年來，鐵電材料於生活中已被廣泛應用，因為被視為新興技術之非揮發性記憶體之一，鐵電材料記憶體(FeRAM)被應用最多。又因鐵電閘極場效式電晶體(FeFET)不需額外的記憶電容，可高密度整合而備受矚目。鐵電閘極場效式電晶體(FeFET)有讀寫速度快、操作電壓低、操作次數高…等許多優點。縱使如此，卻一直在量產上遇到瓶頸，其原因主要是傳統的常用鐵電材料，如PZT、SBT等有機材料無法直接整合於現今CMOS技術上。根據過去的研究發現使用二氧化鉿為基底可以展現出鐵電材料之特性，其不僅在CMOS技術上為常用的高介電係數材料，且相對傳統鐵電材料成本低上很多。 此篇碩士論文，實現了以氧化鋯鉿為基底的鐵電材料電容結構利用鎳的金屬特性在900℃退火後，在正負5V量測到約1.5V的記憶窗(ΔVFB)，且漏電流密度小，透過變頻和變溫的量測，記憶窗並不會縮減，且和緩衝層有不錯的介面特性。

Recently, ferroelectric materials have been widely used in modern life. Because it is one of the new-technological nonvolatile memory, ferroelectric random access memory (FeRAM) has large portion of ferroelectric materials. Also ferroelectric random access memory (FeRAM) is capacitor-less, so it was attracted much attention because of high density integration. Ferroelectric field-effect-transistor (FeFET) has many advantages, such as short program/erase times, low operating voltage, and high endurance cycle. Nevertheless, mass production has not been successful up to now. The main problem of FeFET approach is integration of conventional ferroelectric materials (e.g. PZT, SBT) into CMOS technology. Recent studies have discovered that HfO2 based thin films show the characteristics of ferroelectric material. HfO2 is high dielectric constant material where CMOS technology commonly used. Compare with conventional ferroelectric materials, the cost is much lower too. In this thesis, we achieved the HfZrO with Ni electrode MFIS capacitor have better ferroelectric properties after annealing at 900℃. The memory window (ΔVFB) of 1.5V is obtained under 5V operation and lower leakage density. The memory window does not decrease through the variable frequency and temperature measurement. On the other hand, it has good interface characteristics of buffer layer.