介面緩衝層氧化物對氧化鋯鉿金屬-氧化物-半導體鐵電電容的影響

Abstract

鐵電材料已廣泛運用於生活中，應用上以鐵電記憶體(FeRAM)所佔比例最多，因為其被視為新興非揮發性記憶體之一，其中的鐵電閘極場效式電晶體(FeFET)因可高密度整合而頗受矚目。鐵電閘極場效式電晶體(FeFET)有許多優點，如低操作電壓、高操作次數、讀寫速度快等。不過卻一直無法真正量產，主要的原因是傳統常用的鐵電材料，如PZT、SBT等有機材料一直無法直接整合在現今的CMOS技術上，近年來的研究發現以二氧化鉿為基底能展現出鐵電材料的特性，二氧化鉿不僅在CMOS技術上為常用的高介電系數的材料，且成本相對於傳統鐵電材料低上很多。 在這篇碩士論文中，實現了氧化鋯鉿材料鐵電電容結構在950℃退火後，在5V量測到約0.7V的記憶窗(ΔVFB)，且漏電流密度小(~2╳10-7A/cm2)，透過變頻和變溫的量測，記憶窗並不會縮減，且和緩衝曾有不錯的介面特性。

Ferroelectric materials have been widely used in modern life. Among all applications, ferroelectric random access memory (FeRAM) has a large portion of ferroelectric materials due to a candidate of emerging nonvolatile memory, in which ferroelectric-gate field effect transistor (FeFET) was attracted much attention because of high density integration. 1T FeRAM (FeFET) has many advantages, such as low operating voltage, high endurance cycle and short write/erase times. However, practical implementation has not been successful up to now. The main problem of the FeFET approach is integration of the conventional ferroelectric materials (e.g. PZT, SBT) into CMOS technology. Recently, there are many studies have found that the HfO2 based thin films show the characteristics of a ferroelectric material. HfO2 is the high dielectric constant material which is commonly used in CMOS technology. The cost with conventional ferroelectric materials is much lower too. In this thesis, we achieved the ZrHfO MFIS capacitor have better ferroelectric properties after annealing at 950℃.The memory window(ΔVFB) of 0.7 V is obtained under 5V operation and lower leakage current density(~2╳10-7A/cm2).The memory window (ΔVFB) does not decrease through the measurement frequency and variable temperature. Besides it has good interface characteristics of the buffer layer