Advancing X-Ray Scattering Metrology Using Inverse Genetic Algorithms

Published

July 7, 2016

Author(s)

Adam F. Hannon, Daniel F. Sunday, Donald A. Windover, Regis J. Kline

Abstract

We compare the speed and effectiveness of two genetic optimization algorithms to the results of statistical sampling via a Markov Chain Monte Carlo algorithm to find which is the most robust method for determining real space structure in periodic gratings measured using critical dimension small angle X-ray scattering. Both a covariance matrix adaptation evolutionary strategy and differential evolution algorithm are implemented and compared using various objective functions. The algorithms and objective functions are used to minimize differences between diffraction simulations and measured diffraction data. These simulations are parameterized with an electron density model known to roughly correspond to the real space structure of our nanogratings. The study shows that for X-ray scattering data, the covariance matrix adaptation coupled with a mean- absolute error log objective function is the most efficient combination of algorithm and goodness of fit criterion for finding structures with little foreknowledge about the underlying fine scale structure features of the nanograting.

Citation

Journal of Micro/Nanolithography, MEMS, and MOEMS

Volume

15

Issue

3

Pub Type

Journals

Download Paper

https://doi.org/10.1117/1.JMM.15.3.034001

Keywords

X-ray scattering, genetic algorithm, covariance matrix adaptation evolutionary strategy, differential evolution, Markov Chain Monte Carlo, nanostructure, metrology

Citation

Hannon, A. , Sunday, D. , Windover, D. and Kline, R. (2016), Advancing X-Ray Scattering Metrology Using Inverse Genetic Algorithms, Journal of Micro/Nanolithography, MEMS, and MOEMS, [online], https://doi.org/10.1117/1.JMM.15.3.034001 (Accessed October 13, 2025)