A Century of Ellipsometry
                                         演讲者：D. E. Aspnes
Department of Physics
North Carolina State University, Raleigh, NC 27695-8202 USA
Abstract
Although ellipsometry originated with Paul Drude in the late 1800’s, widespread applications were not possible until the development of small, cheap minicomputers that could not only perform the calculations necessary to convert the data into sample properties but also acquire data directly. Advances since then have been symbiotic, with the improved diagnostic capabilities offered by ellipsometry leading to advances in semiconductor technology and vice versa. Spectroscopic ellipsometry (SE) is now an indispensible tool in this area. Our current capabilities in information handling, high-speed computation, and the cell phone that you now take for granted would not exist without the diagnostics currently provided by SE.
Here, I review the developments that have occurred, discussing configurations, how data are described, and how they are analyzed. Driven by the increasing needs of the semiconductor industry and increasing interest in materials that are optically uniaxial or biaxial, more powerful configurations and in particular systems that can take entire spectra at once are now in widespread use. Scanning and photodiode-array detectors represent different approaches to data acquisition with specific advantages and disadvantages. Although coherency vectors represent more basic physics, Mueller matrices that connect Stokes vectors are a common way of representing the results of ellipsometric measurements on optically complicated samples. Mueller matrices require dual-modulator configurations for their complete determination. Even so, the amount of information available about a sample remains limited by the reflectance Jones matrix although dual-modulator systems provide cross-checks on depolarization, accuracy, and instrument performance that are otherwise unavailable or available only incompletely. Applications in integrated-circuits technology place the highest premium on accuracy, requiring more detailed system transfer functions. They also take advantage of the reflectance as well as ellipsometric data available from current photometric designs.
Results discussed include imaging ellipsometry, real-time determination of critical dimensions in semiconductor technology (the RT/CD application), treatment of biplate compensators as coupled Fabry-Perot cavities, the additional advantages provided by polarimetry (ellipsometry combined with reflectometry) in thin-film measurements, and monitoring and even controlling thin-film deposition and epitaxy. The field is now expanding rapidly into new areas, particularly biology, where the capability of obtaining information about systems in their natural aqueous environments has obvious, and significant, advantages.
Brief CV
1965年获得美国伊利诺大学香槟分校物理博士学位, 后去贝尔实验室从事前沿科学研究，1992年起任职于美国北卡罗利纳州立大学，杰出教授，1998年当选美国科学院院士，为现代椭圆偏振光谱学的发展作出了先驱性研究贡献，在核心专业期刊发表了330多篇高水平学术研究论文，被授权20多项国际专利。
日期：2012年7月2日
时间：下午2：00
地点：物理楼138会议室