Leakage detector in an immersion lithography apparatus

摘要

A lithographic apparatus includes a substrate table (WT) to hold a substrate (W); a substrate table position measurement system (WTPM) to measure a position quantity of the substrate table, a projection system (PS) to project a patterned radiation beam onto a target portion of the substrate, a fluid supply system (LS) to supply an immersion fluid in a space between a downstream lens of the projection system and the substrate, and a fluid supply system position measurement system (LSP) to measure a position quantity of the fluid supply system. To prevent a collision between the fluid supply system and the substrate table, a damage control system (DCON) of the lithographic apparatus may include a calculator (CALC) to calculate a dimensional quantity of a gap between the fluid supply system and the substrate table from the positioned quantity of the substrate table and the position quantity of the fluid supply system. The damage control system may generate a warning signal when the dimensional quantity goes beyond a predetermined safety level.