In-situ measurement of lens aberrations in lithographic tools usingCTC-based quadratic aberration model

摘要

With ever decreasing of feature sizes, the measurement of lens aberration has become increasingly important for theimaging quality control of projection lithographic tools. In this paper, we propose a method for in-situ aberrationmeasurement based on a quadratic aberration model, which represents the bilinear relationship between the aerial imageintensity and the Zernike coefficients. The concept of cross triple correlation (CTC) is introduced, so that the quadraticmodel can be calculated in a fast speed with the help of fast Fourier transform (FFT). We then develop a method for theZernike coefficients characterization using the genetic optimization algorithm from the through focus aerial images of anine contacts mask pattern. Simulation results demonstrate that this method is simple to implement and will havepotential applications for in-situ metrology of lens aberration in lithographic tools.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.