Rigorous Mask Modeling beyond the Hopkins Approach

This paper presents the implementation of an imaging algorithm that extends the Hopkins approach in order to cope with the demanding requirements of state of the art lithography. Rigorous mask simulation for oblique angles of incidence is integrated into our model of a lithographic projection system. In order to show the capabilites, Chromeless Phase Lithography (CPL) masks are studied with the new implementation. Immersion conditions are applied and a benchmark against the Hopkins approximation is carried out. An impact on aerial-image formation and on lithographic-process simulation is shown. It is possible, that the approach will be relevant for mask optimization.