摘要 |
<p>A lithographic projection apparatus comprises an optical element such as a multilayered EUV mirror (10,13,14) with protective capping layers (17) of diamond-like carbon (C), boron nitride (BN), boron carbide (B4C), silicon nitride (Si3N4), silicon carbide (SiC), B, Pd, Ru, Rh, Au, MgF2, LiF, C2F4 and TiN and compounds and alloys thereof. The final period (11,12) of a multilayer coating may also be modified (15,16) to provide improved protective characteristics. <IMAGE></p> |