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7 June 1996 Imaging parameter optimization for advanced lithography based on STELLA
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A methodology and software package STELLA (statistical evaluation of linewidth control for lithographic application) have been developed, which allow the optimization of imaging parameters for advanced optical lithography. The technique is based on calculating the CD variation distribution versus imaging parameters assuming specific process typical distributions of inter-die defocus and relative dose variation. As results a histogram of the CD distribution, the corresponding standard deviation, and the mean CD are obtained. With these numbers optimized processing conditions can be defined. The working scheme of our software package will be demonstrated. The technique will be compared to state-of-the-art imaging parameter optimization techniques. The applicability to real IC designs will be demonstrated. Our simulator allows consideration of the impact of basic resist performance parameters, like Gamma and dark resist thickness loss. Furthermore, it can deal with side lobe phenomena caused by phase-shifting masks, and considers resist feature slope criteria and resist feature loss criteria. Any NA, any scheme of illumination, and any type of mask can be applied. The simulator is well suited to compare various imaging techniques to each other. Simulation results will be compared with experimental data for advanced i-line using lithography circular and annular illumination, as well as binary and phase-shifting masks.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rainer Pforr and Leonhard Mader "Imaging parameter optimization for advanced lithography based on STELLA", Proc. SPIE 2726, Optical Microlithography IX, (7 June 1996);

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