金屬(Al)/氧化鉿(HfO2)/矽(Si)薄膜電容器與場效電晶體之製作與電性分析

Fabrication and Characterization of Metal-Oxide-Si Capacitors and Field Effect Transistors Using HfO2 Gate Oxide

連瑞宗(Ruei-Zong Lian)

指導教授 ： 李雅明

國立清華大學/電機資訊學院/電子工程研究所/碩士(2006年)

https://doi.org/10.6843/NTHU.2006.00215

摘要

中 文 摘 要
金屬(Al)/氧化鉿(HfO2)/半導體(p-Si)結構的電容器、N通道場效電晶體與P通道場效電晶體在本實驗中成功以RF sp被製造。以氧化鉿為絕緣層的電容器在|VG－VFB|＝1V的偏壓下漏電流為0.02 A/cm2，其介電常數k值從電容器C-V曲線得到為12。對電容器作變溫電性量測，以討論漏電流機制，結果顯示當溫度達498K左右且電場為1.2~1.8MV/cm時，在Al/HfO2介面的漏地流傳導機制為蕭基發射所主導。對電晶體而言，改變300K到420 K的溫度變化來探討N通道電晶體特性的溫度相依關係。透過使用split-C-V方法來萃取通道中載子遷移率，其中對N通道電晶體的電子遷移率是172 cm2/V-s，而P通道電晶體的電洞遷移率是16 cm2/V-s。對於N通道的電子遷移率衰減機制在本實驗中是被探討的，被聲子散射限制住的電子遷移率在固定有效電場為0.5 MV/cm且溫度變化從300到420 K下是正比於T-2.24，而被表面粗糙散射限制住的電子遷移率在室溫下且有效電場為0.5-1.2 MV/cm時是正比於Eeff-0.56。
從電晶體的漂移-擴散理論得到的載子遷移率在奈米尺度下並不是一個明確的數量值，其中電晶體的單通量散射理論是在文獻中被引入來取代在小尺寸的電子遷移率，以HfO2為閘極氧化層電晶體的通道散射是被探討的，而其背向散射因子(backscattering coefficient)成功的在本實驗中量測出來，數值為0.51-0.11相對應的通道長度為40μm到8μm，對於相關的背向散射因子的詳細分析將在文章中介紹。
至於材料物性方面，作了二次質譜儀縱深分佈 (Secondary Ion Mass Spectrometry : SIMS)、原子力顯微鏡 (Atomic force microscope : AFM)、X光繞射 (X-Ray Diffraction : XRD)等物性分析與原子力顯微鏡 (Atomic force microscope : AFM) 分析。

關鍵字

氧化鉿 ； 載子遷移率

並列摘要

Abstract
Metal-insulator-semiconductor (MIS) capacitors, n-channel and p-channel metal-oxide-semiconductor (MOS) transistors with HfO2 gate dielectric were fabricated. The HfO2 films were deposited by RF sputtering. The leakage current of MIS capacitors is 0.02 A/cm2 at |VG-VFB| = 1V. Schottky emission is found to be the dominating mechanism at 498 K in the electric field from 1.2 MV/cm to 1.8 MV/cm. The temperature dependence of NMOS transistor characteristics was studied in the temperature range from 300 K to 420 K. The carrier mobility is measured by the split C-V method. The maximum mobility of NMOS transistor is 172 cm2/ V-s while the maximum mobility of PMOS transistor is 16 cm2/ V-s. The mobility degradation mechanism of NMOS transistor was studied. The electron mobility limited by phonon scattering is proportional to T-2.24 at the effective normal field Eeff of 0.5 MV/cm between 300 K and 420 K. The electron mobility limited by surface roughness is proportional to Eeff-0.56 in the fields of 0.5＜Eeff＜1.2 MV/cm at 300 K.
The mobility is an important parameter in traditional drift-diffusion theories of MOS transistor, but it is not a well-defined quantity in nanoscale MOS transistors. In this work, the experimental results were compared with the one-flux scattering theory. The backscattering of electrons of NMOS transistor with HfO2 gate dielectric was studied. The backscattering coefficient rc is obtained by measuring the temperature dependence of the drain current. The value of rc is in the range 0.11-0.51 with the gate length varying from 8 μm to 40 μm.

參考文獻

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