Initial Wafer Heating Analysis for a SCALPEL Lithography System

A high-throughput SCALPEL tool will employ a typical current of 30 mu A and electron column potential of 100 KV, delivering power up to ~3 W through a 0.25 mm (wafer scale) square optical subfield. Electrons lose energy to form heat in the upper 60 microns of a wafer in vacuum during a sub-field exposure period of ~200 microseconds, creating significant local wafer heating at the time of image formation. Our initial analysis indicates that expansion-induced pattern placement errors will require a sub-field position correction strategy.