Methodology for Accurate and Rapid Simulation of Large Arbitrary 2D Layouts of Advanced Photomasks

摘要

The edge domain decomposition method (edge-DDM) is developed as a very powerful extension of the domain decomposition methods presented in for the rapid and accurate simulation of light scattering from advanced photomasks. The range of validity of the method is systematically evaluated and it is found to be accurate for wavelength-sized mask features with large vertical topography. The error associated primarily with neglecting corner effects is seen to concentrate at the extremities of the spectrum of propagating plane waves and is therefore filtered-out by the NA and the larger than one reduction factors in typical projection printing systems. A possible algorithmic implementation of the method, that involves rigorous pre-calculation of the edge-diffraction of all types of edges present in the layout, is presented for the simulation of large and arbitrary 2D layouts of alt. PSMs. A speed-up factor of 172,800 (1sec vs. 2days) is shown in the simulation of simple 3μm by 3μm (4X) 2D layouts (isolated hole and isolated island) with accuracy better than 99% compared to the rigorous 3D simulation of the mask diffraction. An example of the edge-DDM applied on a large 12μm by 16μm 2D layout of a 0°/90°/270°alt. PSM, where the near fields are estimated in less than 1min, is also presented. Spectral matching of the edge-diffraction with more compact piecewise constant models is shown to lead to additional speed-ups of the edge-DDM.