Methods for benchmarking photolithography simulators: part II

Numerical simulation has become an indispensable tool for the design and optimization of photolithographic processes. Because the semiconductor industry now relies heavily on these tools, it is necessary to be able to benchmark their accuracy - as feature sizes continue to shrink, the numerical error in these simulators must decrease as well. In a previous paper, we proposed benchmarks for aerial image calculation that were drawn from the optics literature. Because these benchmarks were closed-form solutions, we could use these results as an absolute standard for determining the numerical accuracy of an aerial image calculation. In the current study, we continue this effort by presenting closed-form solutions that can serve as benchmarks for the resist response to the projection optics. Benchmarks are proposed for film stack reflectivity and image in resist. Specific results will be presented for PROLITH.