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

We present a 'universal' phenomenon of mass accumulation and its sensing on nanostructures due to electron beam cracking of residual gas molecules during electron beam scanning. Though the extent of this phenomenon is limited to a very small increment in mass or thickness, it has significant implications for both the scientific and technological aspects 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 of the order of picometre (fraction of a monolayer) only. Direct measurement of a mass 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) electron energy and beam current, (ii) environment within the chamber (presence or absence of a precursor gas) and (iii) partial exposure of the nanopillars to the e-beam.