Charging dynamics of integrated circuit passivation layer probe holes in the electron beam tester

Abstract

Numerical simulations show that the sidewall of a probe hole in the SiO2 passivation layer of an integrated circuit charges negatively when a 1 keV beam is probing a test point inside the probe hole. The negative charges on the sidewalls create a local electric field that suppresses the low-energy secondary electrons and at the same time focuses the higher-energy secondary electrons. These potential barrier and lens effects degrade the detected secondary electron signal and may have significant consequences for voltage contrast measurements.