Measuring and modeling optical diffraction from subwavelength features

We describe a technique for studying scattering from subwavelength features. A simple scatterometer was developed to measure the scattering from the single-submicrometer, subwavelength features generated with a focused ion beam system. A model that can describe diffraction from subwavelength features with arbitrary profiles is also presented and shown to agree quite well with the experimental measurements. The model is used to demonstrate ways in which the aspect ratios of subwavelength ridges and trenches can be obtained from scattering data and how ridges can be distinguished from trenches over a wide range of aspect ratios. We show that some earlier results of studies on distinguishing pits from particles do not extend to low-aspect-ratio features

The scattering of 10.6 micron radiation from ground glass surfaces

Thesis (M.S.)--University of Rochester. College of Engineering and Applied Science. Institute of Optics, 1969. This thesis was digitized by the Institute of Optics in 2014 and was determined to have lapsed into the public domain. If you are the author and have questions about the digitization of your work, please contact Kari Brick, Graduate Program Coordinator for the Institute of Optics, at [email protected]. Other contact information for the Institute is available at http://www.optics.rochester.eduThe scattering of light from optically rough surfaces is examined theoretically following the development by Beckmann. This theory describes the rough surface by gaussian statistics and the parameters S, the rms height deviations for the surface, and T, the correlation distance. The distribution of scattered light then consists of a (generally) sharply peaked specular term and a more slowly varying diffuse term. For a particular angle of incidence, the magnitude and shape of these two terms are determined only by the parameters S and T. An experimental comparison was made with the theoretical predictions for 10.6 micron radiation scattered from several ground glass samples. Independent measurements were made of the surface parameters using a Proficorder tracing instrument. From the physical traces of the surfaces values of 0.4 microns < S < 5.1 microns and 9.3 microns < T < 41.0 microns were obtained. The experimental results show a significant specular component is obtained when using the 10.6 micron radiation. For a finely ground surface this value may approach 50%. Experimental scattering profiles are given for the various samples tested and a comparison made with the Beclimann scattering theory