Lithographic apparatus and device manufacturing method

An immersion lithographic apparatus comprising:

• a projection optical system arranged to project an image of a pattern onto a substrate to expose the substrate;
• a fluid handling system configured to supply immersion liquid to, at least partly confine immersion liquid to, and/or remove immersion liquid from, at least a portion of the substrate being exposed;
• and
• a fluid temperature control unit configured to control the temperature of the immersion liquid in the fluid handling system at a fluid supply location, the control unit comprising:
• a first temperature sensor having a location and being configured to measure the temperature of the fluid at a position remote from the fluid supply location,
• a second temperature sensor configured to measure the temperature of the fluid at the fluid supply location, and configured such that its calibration error relative to the first temperature sensor can be measured in situ,
• a fluid transfer path configured to transfer the fluid from the location of the first temperature sensor to the fluid supply location, and
• a calculation unit configured to calculate a calibration temperature error in the second temperature sensor using a difference in measured temperatures between the first and second temperature sensors at at least two different, known, mass flow rates.

A method of controlling the temperature of a fluid at a fluid supply location in an immersion lithographic apparatus, the method comprising:

• measuring a temperature of the fluid at a location remote from the fluid supply location using a first temperature sensor;
• transferring the fluid from the location of the first temperature sensor to the fluid supply location;
• measuring a temperature of the fluid at the fluid supply location using a second temperature sensor;
• and
• calculating a temperature calibration error of the second temperature sensor relative to the first temperature sensor in situ using a difference in measured temperatures between the first and second temperature sensors at at least two different, known, mass flow rates.