RADIATION SOURCE, LITHOGRAPHIC APPARATUS, AND DEVICE MANUFACTURING METHOD

摘要

A spectral purity filter is configured to transmit extreme ultraviolet (EUV) radiation and deflect or absorb non-EUV secondary radiation. In an embodiment, the spectral purity filter includes a body of material highly transmissive of EUV radiation and a layer of material highly reflective of non-EUV secondary radiation located on a radiation incident side of the body. In an embodiment, the spectral purity filter includes a body of material highly transmissive of EUV radiation and a layer of high emissivity material on an end of the body.