We present a new optical technique for dimensional analysis of sub 100 nm sized targets by analyzing through-focus images obtained using a conventional bright-field optical microscope. We present a method to create through-focus image maps (TFIM) using optical images, which we believe unique for a given target. Based on this we present a library matching method that enables us to determine all the dimensions of an unknown target. Differential TFIMs of two targets are distinctive for different dimensional differences and enable us to uniquely identify the dimension that is different between them. We present several supporting examples using optical simulations and experimental results. This method is expected to be applicable to a wide variety of targets and geometries.
Proceedings Title: Proceedings of SPIE, Metrology, Inspection, and Process Control for Microlithography XXII, John Allgair, Editor
Conference Dates: February 24-29, 2008
Conference Location: San Jose, CA
Conference Title: Advanced Lithograpgy
Pub Type: Conferences
Through-focus image map, Optical CD (OCD) metrology, Overlay, Defect analysis, Library matching, Optical microscope, Optical inspection, Process control