Lithographic apparatus, device manufacturing method, and device manufactured thereby

摘要

Pre-cleaning or in situ cleaning of optical components for use in a lithographic projection apparatus can be carried out by irradiating the optical component with microwave and/or infra-red radiation, preferably infra-red radiation having a wavelength or a range of wavelengths in the range of from 1000 cm^-1 to 4600 cm^-1. This technique may be suitable for cleaning a mask. By monitoring the absorption of microwave and/or infra-red radiation directed at a contaminated optical component, the degree of contamination of said component can be qualified. This method may also be suitable for reducing the partial pressure of water in EUV apparatus.