Highly resolved edge detection and localization of micro structures using optical 3D measurements and simulations

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Disturbing effects such as batwings restrict the accuracy of edge localization of microstructures in optical 3D measurement. This is true especially for those measurement systems which are based on either white-light interferometry or focus detection. Because of their outstanding height resolution capabilities such instruments are widely used in practise. However, production in micro- and nanotechnology needs detailed knowledge of edge locations. This is a prerequisite for the determination of dimensional accuracy and finally guarantees the required function of a measuring object.In this context the requested research project addresses prospects of improvement of measurement accuracy using white-light interferometry or focus detection techniques. The project aims at studying disturbing effects occurring in context with three-dimensional measurement of edge structures. Based on these studies approaches of an accurate determination of edge locations shall be obtained and verified for the different measurement principles. The research work consists of experimental investigations of white-light interferometry and focus detection, simulations of light propagation using Kirchhoff diffraction theory and rigorous coupled wave analysis (RCWA) as well as comparative measurements of calibration specimens based on reference measuring systems (atomic force microscopy and confocal microscopy). Since the initial research work of both applicants Prof. Dr. E. Manske (TU Ilmenau) and Prof. Dr. P. Lehmann (University of Kassel) complement each other in an ideal way with respect to the relevant measurement principles, the theoretical basics of the simulation models, and the instruments available for reference measurement, they apply for a cooperative research project. The intended cooperation accomplishes synergy effects, since the simulation can be adapted to both measurement principles with reasonable modification and the results achieved can be evaluated comparatively with respect to accuracy and optimization capabilities for precise edge localization. The nano-measuring machine previously developed at TU Ilmenau builds the platform for high precision measurements by use of different sensors.