Surface State Variation during Scanning in a Low-Voltage SEM and Its Effect on of Relief Structure Sizes

Abstract

The variation of low-energy slow secondary electron emission from the surface of relief structures (bumps) during their prolonged scanning in a low-voltage scanning electron microscope is estimated. The variation nature depends on the bump region profile, which is especially complex near relief structure angles. As a result, corresponding curve portions of the bump video signal, which results in an increase or even a decrease in geometrical sizes of these portions. The emission variation is explained by local charge induction in the natural oxide layer on the silicon surface. The portion size also changes due to contamination film bump deposition on the surface. Presumably, its deposition depends on charges induced on the bump surface and, hence, is poorly reproducible. The case of the absence of contamination broadening of a bump due to its prolonged scanning is fixed.