Wed, 20 Aug 2008 22:07:23 BST CiteULike: eyliu's Ward http://www.citeulike.org/user/eyliu/author/Ward CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/eyliu/article/2731178 <i>Physical Review Letters, Vol. 19, No. 10. (1967), 556.</i> Optical Third-Harmonic Generation in Gases GHC New JF Ward doi:10.1103/PhysRevLett.19.556 Physical Review Letters, Vol. 19, No. 10. (1967), 556. 2008-04-28T22:26:14-00:00 1967 Physical Review Letters 19 10 556 American Physical Society nonlinear-optics http://www.citeulike.org/user/eyliu/article/1072935 <i>Metrology, Inspection, and Process Control for Microlithography XVIII, Vol. 5375, No. 1. (2004), pp. 564-575.</i><br /><br />Scatterometry is a novel optical metrology that has received considerable attention in the silicon industry in the past few years. Based on the analysis of light scattered from a periodic sample, scatterometry technology can be thought of as consisting of two parts known as the forward problem and the inverse problem. In the forward problem, a scatterometer "signature" is measured. The signature is simply the measured optical response of the scattering features to some incident illumination, like laser light. In the inverse problem, the signature is analyzed in order to determine the parameters (such as linewidth, thickness, profile, etc) of the scattering features. Typically a rigorous electrodynamic model is used in the solution to the inverse problem, but due to the complexity of the model there is no direct analytic solution. Instead, a variety of numerical methods to solve the inverse problem have been proposed and utilized. The earliest widely used method of solution to the inverse problem involved the generation of a "library" of scatter signatures corresponding to discrete parameter combinations of the structure being measured. Once the library was generated, it was then searched in order to determine the best match to the measured signature. The parameters of the best match were then reported as the parameters of the measured signature. As the technology matured, other methods such as model optimization techniques also emerged. In fact, a variety of alternate techniques have been explored and reported, but a general study comparing the results (and hence the strengths and weaknesses) of the various techniques has yet to be performed. In this research, we shall report results from using several different solutions to the inverse problem on two applications (patterned resist and etched poly). The solution methods shall include the classic library search method as well as three common optimization methods. The results will show that each technique has strengths and weaknesses. For example, the library search methods are generally the most robust but also the most time consuming, and the optimization methods, while fast, are prone to reporting a local but not global minima. Comparison of solutions to the scatterometry inverse problem Christopher Raymond Michael Littau Andrei Chuprin Simon Ward doi:10.1117/12.538662 Metrology, Inspection, and Process Control for Microlithography XVIII, Vol. 5375, No. 1. (2004), pp. 564-575. 2007-01-28T20:45:59-00:00 2004 Metrology, Inspection, and Process Control for Microlithography XVIII 5375 1 564 575 SPIE scatterometry http://www.citeulike.org/user/eyliu/article/798052 <i>Nature, Vol. 442, No. 7103., pp. 664-666.</i> Tracking the motion of charges in a terahertz light field by femtosecond X-ray diffraction A Cavalleri S Wall C Simpson E Statz DW Ward KA Nelson M Rini RW Schoenlein doi:10.1038/nature05041 Nature, Vol. 442, No. 7103., pp. 664-666. 2006-08-11T23:51:45-00:00 Nature 0028-0836 442 7103 664 666 Nature Publishing Group terahertz