Optical and electrical properties of plasma-oxidation derived HfO2 gate dielectric films
Optical and electrical properties of plasma-oxidation derived HfO2 gate dielectric films
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DOI：
10.1016/j.apsusc.2006.07.055
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发表时间：
2007-01-30
影响因子：
6.7
通讯作者：
Zhang, L. D.
中科院分区：
文献类型：
--
作者：
He, G.;Zhu, L. Q.;Zhang, L. D.
采用等离子体氧化溅射金属Hf薄膜的方法，在Si（100）衬底上制备了高k栅介质HfO 2薄膜。利用椭圆偏振光谱（SE）和电容-电压（C-V）特性研究了薄膜的光学和电学性质与退火温度的关系。X射线衍射（XRD）测试表明，沉积态HfO 2薄膜基本为非晶态。基于一个参数化的Tauc-Lorentz色散模式，已发现实验和模拟光谱之间的良好协议，和退火温度相关的沉积和退火的薄膜的光学常数被系统地提取。随着退火温度的升高，折射率和消光系数k增加，观察到由于形成更紧密堆积的薄膜和目标HfO 2膜中的散射效应的增强。讨论了复介电函数随退火温度的变化和光学带隙的减小。提取的直接带隙相关的结构变化从5.77，5.65，和5.56 eV的沉积和退火的薄膜在700和800摄氏度，分别。从C-V测量中发现，退火后累积电容值减小，这可以归因于退火后具有较低介电常数的界面层的生长。由于退火后产生的正电荷，平带电压负移。(c)2006 Elsevier B. V.保留所有权利。
High-k gate dielectric HfO2 thin films have been deposited on Si(1 0 0) by using plasma oxidation of sputtered metallic Hf thin films. The optical and electrical properties in relation to postcleposition annealing temperatures are investigated by spectroscopic ellipsometry (SE) and capacitance-voltage (C-V) characteristics in detail. X-ray diffraction (XRD) measurement shows that the as-deposited HfO2 films are basically amorphous. Based on a parameterized Tauc-Lorentz dispersion mode, excellent agreement has been found between the experimental and the simulated spectra, and the optical constants of the as-deposited and annealed films related to the annealing temperature are systematically extracted. Increases in the refractive index it and extinction coefficient k, with increasing annealing temperature are observed due to the formation of more closely packed thin films and the enhancement of scattering effect in the targeted HfO2 film. Change of the complex dielectric function and reduction of optical band gap with an increase in annealing temperature are discussed. The extracted direct band gap related to the structure varies from 5.77, 5.65, and 5.56 eV for the as-deposited and annealed thin films at 700 and 800 degrees C, respectively. It has been found from the C-V measurement the decrease of accumulation capacitance values upon annealing, which can be contributed to the growth of the interfacial layer with lower dielectric constant upon postannealing. The flat-band voltage shifts negatively due to positive charge generated during postannealing. (c) 2006 Elsevier B.V. All rights reserved.