Radiation source, lithographic apparatus and device manufacturing method

摘要

A lithographic apparatus includes a radiation source configured to produce extreme ultraviolet radiation. The radiation source includes a chamber in which a plasma is generated, and a mirror configured to reflect radiation emitted by the plasma. The mirror includes a multi-layer structure that includes alternating Mo/Si layers. A boundary Mo layer or a boundary Si layer or a boundary diffusion barrier layer of the alternating layers forms a top layer of the mirror, the top layer facing inwardly with respect to the chamber. A hydrogen radical generator is configured to generate hydrogen radicals in the chamber. The hydrogen radicals are configured to remove debris generated by the plasma from the mirror.