Methods for benchmarking photolithography simulators: part III

Abstract

In the past, most lithography simulators have used the thin-mask or Kirchhoff approximation to calculate the diffraction pattern for imaging calculations. This approximation has been very accurate for binary reticles, and rigorous solutions to the full Maxwell equations were only required for "exotic" technologies such as alternating phase-shift masks and chromeless phase lithography (CPL). For the future technology nodes, the thin-mask approximation may be insufficient even for binary reticles. This means that solution of the full Maxwell equations will be required for most, if not all, lithography simulations, and that these simulators must be robust and accurate, especially when used by someone who is not an expert in solving the Maxwell equations.In a previous series of papers, we proposed benchmarks for lithography simulators drawn from the optics literature for aerial image and optical film-stack calculations. We extend this work and present benchmarks here for Maxwell equation solvers. These benchmarks can be easily applied to any mask topography simulator.