The measurement of attogram mass accumulation on nanostructures during e-beamscanning, using carbon nanopillars in resonant mode

Abstract

We present a ‘universal’ phenomenon of mass accumulation and its sensing onnanostructures due to electron beam cracking of residual gas molecules during electronbeam scanning. Though the extent of this phenomenon is limited to a very small incrementin mass or thickness, it has significant implications for both the scientific and technologicalaspects of almost all processes in the nanodomain. Mass accumulation in every frame scan(or per second) is of the order of a few attograms and the thickness of deposition is ofthe order of picometre (fraction of a monolayer) only. Direct measurement of amass or thickness of this order is difficult. Nanopillars having a high resonance ‘Q-factor’ have been successfully exploited for such high precision measurements.The mass accumulation rate has been characterized with respect to (i) electronenergy and beam current, (ii) environment within the chamber (presence or absenceof a precursor gas) and (iii) partial exposure of the nanopillars to the e-beam.