Impact of high-NA half-field to full-field overlay performance by Monte Carlo simulations

Abstract

In an earlier publication, we evaluated simulation methods to explore overlay performance implications when a high-Numerical Aperture (high-NA) Extreme Ultra Violet (EUV) exposure is mixed and matched with a 0.33NA EUV full field exposure. The present contribution goes beyond the method description and aims to quantify the overlay performance impact in such a mix and match case, giving insight into the influence of different sets of overlay corrections. To this aim, the Mont Carlo engine has been updated to accommodate overlay corrections with up to 57 parameters. Since high-NA EUV is not yet available, typical overlay correction terms from IBM's 0.33NA EUV tool have been used to approximate a realistic image placement error fingerprint for our simulations. As a result, we demonstrate the benefit of various overlay correction sets, and the detrimental effect when using different masks for top and bottom half fields. Such information can also help to infer design layout placement decisions to avoid hot spot regions.