An energy analyzer for high-speed secondary electrons accelerated in inspection SEM imaging

An energy analyzer has been developed to evaluate sample charging and voltage-contrast (VC) in a retarding-type scanning electron microscope (SEM) for inspecting semiconductor devices for defects. Since secondary electrons (SEs) are accelerated by the strong retarding field, a high degree of accuracy is needed to evaluate the energy of SEs. The energy analyzer consists of several electrodes for forming suitable electrostatic lens fields. Evaluation results showed that energy resolution of 2 eV for SE incident energy of 9.5 keV was attained and that evaluations of charging voltages on patterned samples were performed quantitatively.