Method and system for inspecting and grounding an EUV mask
A structure for grounding an extreme ultraviolet mask (EUV mask) is provided to discharge the EUV mask during the inspection by an electron beam inspection tool. The structure for grounding an EUV mask includes at least one grounding pin to contact conductive areas on the EUV mask, wherein the EUV mask may have further conductive layer on sidewalls or/and back side. The inspection quality of the EUV mask is enhanced by using the electron beam inspection system because the accumulated charging on the EUV mask is grounded. The reflective surface of the EUV mask on a continuously moving stage is scanned by using the electron beam simultaneously. The moving direction of the stage is perpendicular to the scanning direction of the electron beam.
1. A system for grounding an EUV mask when the EUV mask is inspected by using a charged particle beam, wherein the EUV mask comprises a reflective layer, comprising:
means for conducting charges from the reflective layer of the EUV mask, said conducting means being detachably mounted on the EUV mask and in direct contact with a plurality of edges of the EUV mask, wherein the direct contact includes direct contact with said reflective layer of the EUV mask and wherein said charges are induced by using said charged particle beam; and
means for grounding said charges by directly contacting said conducting means.
2. The system of claim 1 , wherein said conducting means is an electrically conductive cap for mounting on a corner of the EUV mask.
3. The system of claim 1 , wherein said conducting means is an electrically conductive wire for mounting on peripheral regions of the reflective surface.
4. The system of claim 1 , wherein said conducting means is a hollow, electrically conductive cover for mounting on peripheral regions of the reflective surface.
5. The system of claim 1 , wherein said grounding means includes a base and at least an electrically conductive wire protruding from the base.
6. The system of claim 1 , wherein said grounding means includes a base, one fork mounting on the base, and an electrically conductive wire between the two ends of said fork.
7. The system of claim 1 , wherein said grounding means includes a base, one fork mounting on the base, and an electrically conductive band between the two ends of said fork.