SCALPEL Mask-Membrane Charging - Charging of Amorphous Silicon Nitride Thin-Films Irradiated by Fast Electrons

The variety of processes responsible for the charging of a free-standing dielectric film irradiated by the energetic electrons are discussed and the corresponding rates are evaluated. A model of electrostatic charge accumulation in a SiN sub x thin film irradiated by 100 keV electrons is developed and kinetic equations describing the dynamic process are formulated. It is found that the incident energetic electrons, inelastically scattered in the membrane, primarily generate plasmons. The plasmon decay creates electron-hole pairs and contributes to secondary electron (SE) emission. The escape of SEs from the target creates uncompensated positive charge in the membrance that gets eventually localized at high density trap centers uniformly distributed throughout the membrane; this leads to a uniform electrostatic charge accumulation in the membrane. The model used to predict the electrostatic charge accumulation in the SCALPEL SiN sub x mask membranes. It is shown that the SCALPEL mask-membrane charging is defined by the balance of SE escape, charge carriers generation, recombination, trapping and transport processes.