Rigorous EMF simulation of absorber shape variations and their impact on lithographic processes

We present a finite integration technique (RIT) simulator for modelling light diffraction from lithographic masks with complex shapes. This method has high flexibility in geometrical modelling and treating curved boundaries. The inherent feature of FIT allows more accurate rigorous electromagnetic field simulation in complex structures. This technique is also suited for fast EMF simulations and large 3D problems because of its parallelisation potential. We applied this method to investigate the effect of various mask shapes on lithographically printed images. The imaging results were obtained using Dr.LiTHO's imaging simulator. We demonstrate results for attenuated phase-shift mask (PSM) with different absorber deviations from ideal shapes such as footing and oblique sidewalls.