Proximity Effect in Electron Beam Lithography
Explore the concept of proximity effect in electron beam lithography, covering definitions, origins, avoidance techniques, and corrections. Learn about electron-solid interactions, forward and backward scattering, secondary electrons, proximity effect avoidance, dose modulation, and more.
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Presentation Transcript
Electrical and Computer Engineering Department University of Victoria Proximity Effect in EBL by: Zeinab Mohammadi November 2011
Outline Definition Origins Avoidance of Proximity Correction 2
Definition The proximity effect is the change in feature size of pattern as a consequence of nonuniform exposure! Pattern affected by proximity (left), After elimination of proximity effect (Right) 3
Electron-Solid Interactions Forward Scattering Backward Scattering Secondary Electrons 4
Forward Scattering As the electrons penetrate the resist, they experience many small angle scattering events, which tend to broaden the initial beam diameter. 5
Backward Scattering As the electrons penetrate through the resist into the substrate, they occasionally undergo large angle scattering events 6
Secondary Electrons As the primary electrons slow down, much of their energy is dissipated in the form of secondary electrons with energies from 2 to 50 eV and this energy accumulates around patterned areas! Low energy! High energy! 7
Proximity Effect Avoidance Adjust the pattern size Exposure of low energy e-beam Multilayer resists coating techniques 8
Correction Dose Modulation Very common technique with good resolution Background Exposure Correction (GHOST) Time consuming No computation required Extra data preparation and writing time, less Software resolution 9
Conclusion Proximity effect concepts reviewed Reason why it happens discussed Techniques to avoid and correct it considered 10
