Optical system for a multiple-beam scanning electron microscope

A novel optical system for a multiple-beam scanning electron microscope (SEM) is proposed. In the case of multiple-beam SEM, multiple secondary-electron beams passing through the column are inherently blurred because of the large energy spread and broad angular distribution of secondary electrons. To avoid cross-talk between the multiple secondary-electron beams, the optical system is designed such that it is divided into two independent parts: one for primary-beam illumination and one for secondary-electron detection. As the key components for the secondary-electron detection, a scan-cancelling deflector, and accelerating electric field were applied. To demonstrate the proposed optical system, a prototype column with four beams was developed. This column enables four SEM images to be separately but simultaneously acquired with more than 99% of the generated secondary electrons. This result demonstrates that high-speed imaging with the proposed multiple-beam SEM is possible in the near future.

[1]  E. Munro.  Design and optimization of magnetic lenses and deflection systems for electron beams , 1975 .

[2]  J. J. Koning,et al.  Scanning exposures with a MAPPER multibeam system , 2011, Advanced Lithography.

[3]  Shinichi Kojima,et al.  High-current electron optical design for reflective electron beam lithography direct write lithography , 2010 .

[4]  S. Kishimoto,et al.  Development of a pattern to measure multiscale deformation and strain distribution via in situ FE-SEM observations , 2011, Nanotechnology.

[5]  L. Reimer,et al.  Scanning Electron Microscopy , 1984 .

[6]  H. Seiler,et al.  Secondary electron emission in the scanning electron microscope , 1983 .

[7]  P. Kruit,et al.  A large current scanning electron microscope with MEMS-based multi-beam optics , 2012 .

[8]  T. Everhart,et al.  Simple calculation of energy distribution of low‐energy secondary electrons emitted from metals under electron bombardment , 1974 .

[9]  C. W. Hagen,et al.  Parallel electron-beam-induced deposition using a multi-beam scanning electron microscope , 2011 .

[10]  Seungpyo Hong,et al.  Multiscale observation of biological interactions of nanocarriers: From nano to macro , 2010, Microscopy research and technique.

[11]  Elmar Platzgummer,et al.  eMET POC: realization of a proof-of-concept 50 keV electron multibeam mask exposure tool , 2011, Photomask Technology.

[12]  R. Pease,et al.  Secondary electron detection for distributed axis electron beam systems , 2008 .

[13]  Masato Muraki,et al.  New concept for high-throughput multielectron beam direct write system , 2000 .

[14]  M. D. Nijkerk,et al.  High throughput defect detection with multiple parallel electron beams , 2007 .