Real-time determination of electron-beam probe shape using an in situ fiducial grid

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1 Scopus citations


Electron-beam probe shape is typically determined by imaging a known or quasirandom target; however, neither standard targets nor two-dimensional image acquisition and processing are suitable for real-time probe characterization during lithographic exposures. Here a new technique for continuously monitoring probe shape is proposed and evaluated. Fourier analysis of the signal generated by an in situ fiducial grid allows estimation of the x and y widths and rotation of a Gaussian beam. The grid itself is rotated with respect to the beam deflection axes to allow real-time estimation of two-dimensional probe shape from a one-dimensional line scan across the grid. Monte Carlo simulations of beam parameter variances versus signal-to-noise ratio reveal regions of operation where the algorithm's precision is limited by either noise or grid geometry. Experiments using a 1 μm period grid to estimate probe shape as a function of defocus demonstrate the effectiveness of the new approach.

Original languageEnglish
Pages (from-to)2875-2880
Number of pages6
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Issue number6
StatePublished - 2006

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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