Part 1 – Electron Scattering and Proximity Effect


Ulrich Hofmann, Nezih Ünal - GenISys GmbH


  • Electron scattering (forward scattering, back scattering) effect and parameter
  • Monte Carlo simulation to model electron scattering
  • Simulation of spread of energy and proximity effect for different layout scenario
  • Impact of proximity effect on lithography result
  • Proximity Effect Correction basic introduction

Summary of the Webinar:

  • Proximity Effect has major influence on e-beam lithography
    • Electron scattering in the material (resist, layers, substrate) spreads the energy
    • Strength and influence ranges depend on material and acceleration voltage
    • Adjacent features interact with each other, leading to a layout (density) dependent absorbed energy
  • Impact of proximity effect on lithography result depends on tool and process parameter
    • The effective short range blur transfers absorbed energy variation to CD variation
    • The effective beam size depends on e-beam tool parameters
    • beam current, aperture, focus (variation), noise
    • Reasonable exposure time and exposure quality ask for higher beam current
    • The process (specifically resist) is another contributor to effective short range blur
  • Monte-Carlo Simulation is an excellent technique to model electron scattering
    • Point Spread Function (PSF) for different stacks and acceleration voltages
  • Absorbed energy and resist contour at threshold can be simulated by convolution of the layout with the PSF
  • Proximity effect can be corrected by adjusting the dose for uniform absorbed energy