Optical through-focus technique that differentiates small changes in line width, line height, and sidewall angle for CD, overlay, and defect metrology applications

Ravikiran Attota; Richard Silver; Bryan M. Barnes

doi:10.1117/12.777205

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16 April 2008 Optical through-focus technique that differentiates small changes in line width, line height, and sidewall angle for CD, overlay, and defect metrology applications

Ravikiran Attota, Richard Silver, Bryan M. Barnes

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Proceedings Volume 6922, Metrology, Inspection, and Process Control for Microlithography XXII; 69220E (2008) https://doi.org/10.1117/12.777205
Event: SPIE Advanced Lithography, 2008, San Jose, California, United States

Abstract

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.

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Ravikiran Attota, Richard Silver, and Bryan M. Barnes "Optical through-focus technique that differentiates small changes in line width, line height, and sidewall angle for CD, overlay, and defect metrology applications", Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69220E (16 April 2008); https://doi.org/10.1117/12.777205

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