The Rigorous Coupled Wave Approach (RCWA) is acknowledged as a well established diffraction simulation method in
electro-magnetic computing. Its two most essential applications in the semiconductor industry are in optical
scatterometry and optical lithography simulation. In scatterometry, it is the standard technique to simulate spectra or
diffraction responses for gratings to be characterized. In optical lithography simulation, it is an effective alternative to
supplement or even to replace the FDTD for the calculation of light diffraction from thick masks as well as from wafer
topographies. Unfortunately, the RCWA shows some serious disadvantages particularly for the modelling of grating
profiles with shallow slopes and multilayer stacks with many layers such as extreme UV masks with large number of
quarter wave layers. Here, the slicing may become a nightmare and also the computation costs may increase dramatically.
Moreover, the accuracy is suffering due to the inadequate staircase approximation of the slicing in conjunction with the
boundary conditions in TM polarization. On the other hand, the Chandezon Method (C-Method) solves all these
problems in a very elegant way, however, it fails for binary patterns or gratings with very steep profiles where the
RCWA works excellent. Therefore, we suggest a combination of both methods as plug-ins in the same scattering matrix
coupling frame. The improved performance and the advantages of this hybrid C-RCWA-Method over the individual
methods is shown with some relevant examples.