Monte Carlo simulation of charging effects on linewidth metrology

Abstract

Charging effects of scanning electron microscopes on the linewidth metrology of polymethylmethacrylate (PMMA) insulator patterns are investigated using Monte Carlo simulation. It is first revealed in detail how the nonunity yield of electron generation in the PMMA target leads to local charge accumulation and affects the image profile of secondary electrons as charging develops. Then the measurement offset due to charging effects is identified for various target patterns of isolated and array types. Finally, it is concluded that the measurement uncertainty caused by the measurement offset exceeds the error budget limit that will be allowed in the linewidth metrology of the next generation of semiconductors.