Optical scatterometry is a method for the on-line measurement of the geometry of a diffraction grating, which is deduced from diffraction-pattern data. We demonstrate the use of a neural network as a promising method for performing an accurate quantitative characterization of the geometry. As an example, we show the deduction of the geometry of a grating with subwavelength grooves with a rms accuracy of 1.9° for the slope of the groove walls, 0.7 nm for the linewidth, and 1.0 nm for the groove depth.
© 1998 Optical Society of America
(050.1950) Diffraction and gratings : Diffraction gratings
(120.4290) Instrumentation, measurement, and metrology : Nondestructive testing
(120.5820) Instrumentation, measurement, and metrology : Scattering measurements
(260.1960) Physical optics : Diffraction theory
(290.3200) Scattering : Inverse scattering
Ilkka Kallioniemi, Jyrki Saarinen, and Erkki Oja, "Optical Scatterometry of Subwavelength Diffraction Gratings: Neural-Network Approach," Appl. Opt. 37, 5830-5835 (1998)