US Patent 7291569 Fluids for immersion lithography systems

Fluids for use in immersion lithography systems are disclosed. A resistivity-altering substance is introduced into a fluid, making it more conductive. The fluid is then disposed between an immersion head of a projection lens system and a semiconductor wafer during an exposure process. Because the fluid is conductive, electrostatic energy that may develop during the movement of the semiconductor wafer with respect to the projection lens system during the exposure process is discharged through the conductive fluid, preventing damage to an immersion head of the projection lens system, the semiconductor wafer, and sensors of a stage that supports the semiconductor wafer.