MICROSCOPY Vol.43▶No.3 2008
â– Feature Articles: Image formation and detection of signal in SEM

SEM Image Viewed from Simulated Behavior of Penetrating Electrons in Specimens

Tohru Ishitani

Abstract: SEM image using secondary electrons (SE) and/or backscattered electrons (BSE) supplies us with elemental and topography information of the sample surface. The SE and BSE characteristics are discussed using the simulated behavior of penetrating electrons in the sample. For the lower incident-energy (≤several hundred electron-volts), the primary electrons more lose straightness of their penetrations and their spatial ranges become to be as shallow as the SE maximum escape depth of about 10nm. This makes both the SE/BSE images more sensitive to the most surface layers and the low-energy BSE nearer to the high-energy SE in their characteristics. Adjustment of the SE/BSE imaging conditions is important to clearly obtain desired information of the sample.

Key words: SEM, secondary electron, backscattered electron