The backscattering of electrons from complex targets (for example, metal layer on a semi-infinite substrate with a polymer resist film above) has been studied both theoretically and experimentally. The experimental structures were exposed with an electron beam in a "spot mode". The experimental observations of developed disc radius vs. exposure time and metal layer thickness support the simple theory of scattering in such structures. The theory assumes that the backscattering causes enlarging of the exposed area by a constant value. This value is derived from the proposed scattering model based on the Archard's and Kanaya and Okayama's diffusion theories. The radial exposure intensity distribution introduced by the electron beam has been approximated by a Gaussian function.
Kisza, M.; Maternia, Z.; and Radzimski, Zbigniew
"Backscattering of Electrons from Complex Structures,"
Scanning Electron Microscopy: Vol. 1982
, Article 8.
Available at: https://digitalcommons.usu.edu/electron/vol1982/iss1/8