US Patent 7737418 Debris mitigation system and lithographic apparatus

A debris mitigation system for trapping debris coming from a tin debris-generating radiation source is provided. The debris mitigating system includes a debris barrier comprising a plurality of foils, and a cleaning system constructed and arranged to clean the foils. The cleaning system includes a supply unit to provide a liquid alloy to the foils to dissolve and flush trapped debris from the foils. The alloy includes gallium, indium, tin, or any combination thereof.