EUV radiation source apparatus for lithography

An EUV collector mirror for an extreme ultra violet (EUV) radiation source apparatus, comprising:

• an EUV collector mirror body on which a reflective layer as a reflective surface is disposed;
• a heater attached to the EUV collector mirror;
• a drain structure to drain melted metal from the reflective surface of the EUV collector mirror body to a back side of the EUV collector mirror body;
• and
• a drain hole coupled to the drain structure, wherein the drain structure and the drain hole are configured such that the melted metal flows through the drain structure by gravity,
• wherein the drain structure includes a trunk conduit and multiple openings branching from the trunk conduit.

An extreme ultra violet (EUV) radiation source apparatus, comprising:

• an EUV collector mirror;
• a heater attached to the EUV collector mirror;
• a target droplet generator for generating a tin (Sn) droplet;
• a rotatable debris collection mechanism;
• and
• a chamber enclosing at least the EUV collector mirror and the rotatable debris collection mechanism, wherein the EUV collector mirror includes:
• an EUV collector mirror body on which a reflective layer as a reflective surface is disposed;
• a drain structure to drain melted metal from the reflective surface of the EUV collector mirror body to a back side of the EUV collector mirror body;
• and
• a drain hole coupled to the drain structure, wherein the drain structure and the drain hole are configured such that the melted metal flows through the drain structure by gravity,
• wherein the drain structure includes multiple openings each having a bottom comprising a bottom EUV reflective surface.