Research Disclosure

摘要

This research disclosure relates to components for a lithographic system. In particular, it may relate to components for an extreme ultraviolet (EUV) lithographic system that comprises an EUV radiation source. The EUV radiation source may be a laser produced plasma (LPP) radiation source. The components may comprise optical components (for example mirrors) or support structures for such optical components. (Photo)lithography is a process of transferring a pattern to a radiation-sensitive substrate by exposing the substrate to radiation having the pattern. For example, the substrate may comprise a semiconductor wafer coated with a photoresist. 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. One known source of EUV radiation is an LPP radiation source, which is operable to illuminate fuel droplets with laser radiation (provided by a laser) within an EUV source vessel. Typically, tin is used as a fuel in the form of droplets. In order to create EUV radiation, the path of a laser beam is aligned to intercept the droplet stream at a location which may be known as a primary focus. A tin plasma is created when the laser pulses are incident upon a droplet, which then emits EUV radiation. A portion of this EUV radiation is redirected by a collector mirror for use in a lithographic apparatus (for processing semiconductor wafers).