This research disclosure relates to a radiation source. In particular, it relates to a laser-produced plasma (LPP) radiation source used to produce extreme ultraviolet (EUV) by irradiating droplets that produce EUV radiation when irradiated into a plasma slate, and methods of monitoring the same. Such EUV radiation may be directed to a lithographic apparatus. Photolithography (or, lithography) is a process of transferring a pattern to a radiation-sensitive substrate by exposing the substrate to radiation having the pattem. The substrate may be a resist-coated silicon wafer, for example. The patterned substrate may be used to form integrated circuits. The pattern may be imparted onto a beam of radiation using a reticle. Radiation used in a lithographic apparatus may be extreme ultraviolet (EUV). EUV radiation has a wavelength in the range 4-20 nm, for example 13.5 nm. EUV lithography is used in printing such integrated circuits.
展开▼
