Electron scattering backscattering

In the squeezed position, the B radiation is trapped in the gap between the two surfaces and the electrons are backscattered from both of them (J 9). The larger contribution comes from the scattering from the high density material of the metal electrode (due to the Z-dependence of the backscattering power). The f correction which accounts for the backscattering is included in Equation 1. 

For thick substrates, backscattered electrons from the substrate decrease contrast and the minimum dimension increases to about 20 nm. For thick resists, and samples thick compared to the primary electron penetration range, electron scattering in the resist (forward scattering) and backscattering of electrons from the substrate, become more important than the electron interaction range. In these cases, exposure dose is sometimes altered according to the local pattern density to compensate for variations in the backscattered... 

When slow electrons (energy less than about 300 eV) are directed normal to a surface, only a small fraction is elastically backscattered. The remaining electrons are backscattered after losing energy, or are absorbed in the crystal. Only the elastically scattered electrons, about 1 % of the incident number, produce the diffraction patterns with which we are concerned here. 

Backscattered electrons Energies up to Incident beam energy Beam electrons scattered back after collision Atomic number contrast, channeling patterns, magnetic contrast... 

When focusing on the sample, the primary beam interacts with the atoms of the material and causes scattering and various emissions, including secondary electrons (SE), backscattered electrons (BSE), and characteristic X-rays (Fig. 12.2, [7, 8]). 

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