Extended Abbe approach for fast and accurate lithography imaging simulations
This paper presents an extended Abbe based imaging algorithm for faster and more accurate simulations of current and future projection lithography systems. The basics of the physical model and several methods for the evaluation of the new image simulation software are explained. The comprehensive evaluation of the new image simulation software includes convergence tests, comparisons with analytical results, and various methods for the assessment of computed imaging results in terms of intensity difference plots, simulated linewidths, and image slopes. Tests include simulations for two- and three-dimensional thin and rigorous simulated masks, scalar and vectorial computations of intensity distributions in air/immersion liquid (aerial images) and photoresist (bulk images), respectively. The test scenarios range from special settings which result in simple two-beam interferences to large area simulations of more complex mask layouts. The excellent accuracy and computational performance of the new imaging algorithm is demonstrated by a comparison with the well-established imaging algorithm of Fraunhofer IISB. The new imaging algorithms are integrated in the research and development lithography simulator Dr.LiTHO of Fraunhofer IISB.