Phase sensitive parametric optical metrology: exploring the limits of three-dimensional optical metrology

There has been much recent work in developing advanced optical metrology applications that use imaging optics for critical dimension measurements, defect detection and for potential use with in-die metrology. Sensitivity to nanometer scale changes has been observed when measuring critical dimensions of sub-wavelength features or when imaging defects below 20 nm using angle-resolved and focus-resolved optical data. However, these methods inherently involve complex imaging optics and analysis of complicated three-dimensional electromagnetic fields. This paper will develop a new approach to enable the rigorous analysis of three-dimensional through-focus optical images. We use rigorous electromagnetic simulation tools and statistical methods to evaluate sensitivities and uncertainties in the measurement of three dimensional layouts encountered in critical dimension, contour metrology and defect inspection.