Patent ID: 7629055

Claim:
A protective coating system for reflective optical elements for the EUV and soft X-ray range, comprising: an upper coating system having a thickness of 0.7 nm to 9 nm that comprises at least one uppermost layer made of one of the group consisting of an aluminum oxide, a beryllium aluminum oxide, a beryllium magnesium aluminum oxide, a titanium oxide, a magnesium oxide, a magnesium aluminum oxide, a manganese oxide, a nickel aluminum oxide, a sodium titanium oxide, an antimony oxide, a cerium titanium oxide, a cerium oxide, a strontium oxide, a zirconium oxide, a yttrium oxide, a rhodium oxide, a hafnium oxide, a ruthenium oxide, a boron oxide, a beryllium oxide, a calcium titanium oxide, a silicon nitride, a boron nitride, a silicon oxide, and a silicon carbide, and a lower coating system having a thickness of 1 nm to 16 nm that comprises at least one layer made of one of the group consisting of B x C y , Mo x B y , B x N y , Si x N y , Si x C y , Be x O y , Si x O y , Ti, Ti x N y , Cu x Au y , Ni, Ru, Rh, Ir, Au, Pd, Pt, Os, Sm, Gd, Al x O y , K x Cl y , K, Hf, Th x F y , Na x F y , Li x F y , Mg x F y , La x F y , amorphous carbon, Y, Nb, Rh x O y , Ru x O y , Ce, and Si x H y , wherein the protective coating system consists of one layer of a ruthenium oxide as upper coating system, a one layer of ruthenium or one layer of B 4 C as the lower coating system are excluded.