Research Disclosure

摘要

This research disclosure relates to a dose correction apparatus and method that may be used in a lithographic system, for example, in an extreme ultraviolet (EUV) lithographic system. Figure 1 schematically depicts a lithographic system comprising a radiation source and a lithographic apparatus. The radiation source is of a type which may be referred to as a laser produced plasma (LPP) source). A laser, which may for example be a CO_2 laser, is arranged to deposit energy via a laser beam into a fuel, such as tin (Sn), which is provided from a fuel emitter. Although tin is referred to in the following description, any suitable fuel may be used. The fuel emitter may comprise a nozzle configured to direct tin, e.g. in the form of droplets, along a trajectory towards a plasma formation region. The laser beam is incident upon the tin at the plasma formation region. The deposition of laser energy into the tin creates a plasma at the plasma formation region. Radiation, including EUV radiation, is emitted from the plasma during de-excitation and recombination of ions of the plasma.