非晶稀土氧化物高k栅介质材料的制备及物理特性研究

项目名称： 非晶稀土氧化物高k栅介质材料的制备及物理特性研究

项目编号： No.60806031

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 方泽波

作者单位： 绍兴文理学院

项目金额： 20万元

中文摘要： 随着微电子技术的飞速发展，半导体器件的特征尺寸按摩尔定律不断缩小，传统的SiO2栅介质已经无法满足MOSFET器件的要求。因此，寻找高性能的高介电常数（k）栅介质替代传统的SiO2栅介质，已成为国际前沿性的热门研究课题之一。本项目基于高k栅介质的电学测量，获得了有效介电常数为12.6，EOT为1.4 nm、在1 MV/cm时漏电流密度为8×-4 A/cm2的非晶Er2O3薄膜。获得了EOT为1.2 nm、在1 MV/cm时漏电流密度为3.2×-4 A/cm2的非晶Tm2O3薄膜。我们利用X-射线光电子能谱得出Tm2O3相对于Si的价带和导带偏移分别为：3.1±0.2 eV和1.9±0.3 eV，并得出了Tm2O3的禁带宽度为：6.1±0.2 eV。通过常温及低温下对MOS器件I-V的测试，我们系统的研究了Tm2O3薄膜泄漏电流输运机制。对Er2O3 MOS结构电容器的C-V频率色散现象研究，我们提出了Er2O3/SiOx/Si的样品结构模型。通过本项目的开展，我们为替代SiO2的芯片制造工艺提供了多种优异的稀土氧化物基高k栅介质候选材料。

中文关键词： 稀土氧化物；高k栅介质；MOS

英文摘要： The characteristic length of semiconductor devices becomes smaller and smaller with the fast development of microelectronics, according to Moore's law. SiO2, the traditional gate material used in MOSFET devices has met its limits. Exploring gate materials with high dielectrics constant which are used to substitute SiO2 has been one of the most popular research topics in world's research frontier. Transmission electron microscopic measurement shows that the Er2O3 film possesses good thermal stability and forms a sharp interface with its Si substrate after annealing at 700 ℃for 30 minutes in ultrahigh vacuum. Its effective dielectric constant is measured to be 12.6, an effective oxide thickness (EOT) of 1.4 nm is achieved, with a low leakage current density of 8×-4 A/cm2 at electric field of 1 MV/cm after annealing.The dielectric constant of the Tm2O3 film is measured to be 15.2 and an effective oxide thickness of 1.2 nm is achieved. The film has very low trap density, low leakage current density of about 3.2×-4 A/cm2 at 1 MV/cm. The Single crystalline Tm2O3 were deposited on Si（001）substrates by molecular beam epitaxy. By using x-ray photoelectron spectroscopy, the valence and the conduction-band offsets of Tm2O3 to Si are obtained to be 3.1±0.2 eV and 1.9±0.3 eV, respectively. The energy gap of Er2O3 is determined to be 6.1±0.2 eV. We have studied the mechanisms of leakage current in rare earth oxides and the creation of interface states. The C-V characteristic of the single crystal Er2O3 capacitor with a MOS structure is investigated. Frequency dispersion phenomenon is found at high frequencies. A corrected model based on the traditional one is proposed. The ideal fitting curve and reasonable calculated coefficients indicate that the existence of the interfacial SiOx layer is the main reason for the frequency dispersion. Based on model 2(Er2O3/SiOx/Si), we have successfully extracted the k value of high-k gate dielectric and obtained the thickness of the interface layer. From this work, candidate materials which are to substitute SiO2 in chip fabrication technologies and the theoretical directions will be provided.

英文关键词： Rare earth oxides; high k gate dielectric; MOS