Synopsys, Inc.
Lithographic mask functions to model the incident angles of a partially coherent illumination

Abstract:

In the embodiments disclosed herein, an approach based on a mask function M is disclosed. This approach meets the requirement of the Hopkins model and at the same time incorporates the incident angle effects of a given partially coherent illumination. The new mask function M is referred to as a partially coherent mask function (PCMF). In the embodiments disclosed herein, the incident angle effects of individual source points of a given partially coherent illumination are removed from the mask function M and incorporated into a source function G. As a result, use of the partially coherent mask function M does not require an integration over individual plane waves in the illumination, as would be the case with a rigorous mask function M. Therefore, the Hopkins model can be used with partially coherent mask function M and at the same time capture the incident angle effects.