In this thesis an overall three-dimensional workstation-based photolithography simulator is presented that accounts for all of the three lithographic subprocesses of mask imaging, resist exposure/bleaching and resist development. Each of the three simulation phases is described in detail starting at the basic physical roots and ending at a concise description of its implementation.
The imaging module provides two simulation modes that either implement the classical scalar theory of Fourier optics or its vector-valued extension. Binary as well as phase-shifting masks, lens aberrations of arbitrary order, and in-lens filters can be simulated. Off-axis illumination with general apertures is treated by Abbe's method for partially coherent imaging.
The exposure module accounts for resist bleaching, nonplanar topography as well as inhomogeneous resist materials. For the rigorous, vector-valued electromagnetic field calculation the differential method has been extended to the third dimension for the first time and is thus one of the major contributions of this thesis. The numerical performance is studied in great detail with special emphasis on possible stability problems. A comparison with the waveguide model shows the superior performance of the differential method. A special feature of the proposed implementation is the possibility to rigorously simulate the exposure process under partially coherent illumination without increasing the computational demands.
For the development process an already existing three-dimensional surface advancement algorithm has been adapted for lithography specific requirements such as rapidly varying inhomogeneous development rates. The capability of the overall simulator is demonstrated by showing simulation results for the aerial image of a complete layout and for pattern printing over planar as well as nonplanar dielectric and reflective substrates. Although all lithographic steps are considered and the governing physical processes are treated, many topics are open to be developed further. As a direction to future work the most important ones are listed below.