Conditions of Energy and Incident Angle of Primary Beam for Observation of Insulators ' Surface by SEM

Observation of insulators ' surface in low voltage scanning electron microscope (SEM) becomes useful today for various fields of engineering, particularly for the semiconductor micro-device production and inspection. An appropriate condition of energy Ep and incident angle <PV of the primary beam, for which the topographic features of insulators ' surface can be observed without serious negative charging disturbances is considered theoretically. A threshold formula for the observable condition is derived in terms of Ep • cos2 <Pp using the elementary theory of the secondary electron emission. Key words: low voltage SEM, charging, passivated micro-devices, observable condition Electron beam bombardment produces electron- and hole-traps in insulators.12 ' At low primary electron energy, electron- and hole-traps are induced in a surface layer to result in the surface charging. The charging polarity depends on whether or not the total secondary electron yield a. the sum of the secondary electron yield 5 and the backscatter electron yield rj, exceeds unity