Patent Number: 
Section: claims

1. A method of manufacture for an extreme ultraviolet reflective element comprising:providing a substrate;forming a multilayer stack on the substrate, the multilayer stack includes a plurality of reflective layer pairs having a first reflective layer formed from silicon and a second reflective layer formed from niobium or niobium carbide for forming a Bragg reflector; andforming a capping layer on and over the multilayer stack for protecting the multilayer stack by reducing oxidation and mechanical erosion. 2. The method as claimed in claim 1, wherein forming the multilayer stack includes forming the first reflective layer from silicon having a thickness from 3.5 to 4.15 nanometers and the second reflective layer formed from niobium 3.5 nanometers thick or niobium carbide 2.8 nanometers thick. 3. The method as claimed in claim 1, wherein forming the multilayer stack includes forming a barrier layer between the first reflective layer and the second reflective layer, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms, and the barrier layer for reducing the formation of silicide. 4. The method as claimed in claim 1, wherein forming the multilayer stack includes forming a barrier layer between the multilayer stack and the capping layer, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms for reducing the formation of silicide. 5. The method as claimed in claim 1, wherein forming the multilayer stack includes forming a barrier layer between the multilayer stack and the substrate, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms for reducing the formation of silicide. 6. The method as claimed in claim 1, wherein forming the multilayer stack includes:forming a barrier layer between the first reflective layer and the second reflective layer, the barrier layer formed from carbon having a thickness of 5 angstroms; andforming a boundary layer of silicide between the first reflective layer and the second reflective layer, the boundary layer having a reduced thickness based on the barrier layer. 7. The method as claimed in claim 1, wherein forming the capping layer includes forming the capping layer from ruthenium or a ruthenium alloy and forming an absorber layer on and over the capping layer, the absorber layer formed from chromium, tantalum, nitrides, nickel, or a combination thereof. 8. An extreme ultraviolet reflective element comprising:a substrate;a multilayer stack on the substrate, the multilayer stack includes a plurality of reflective layer pairs having a first reflective layer formed from silicon and a second reflective layer formed from niobium or niobium carbide for forming a Bragg reflector; anda capping layer on and over the multilayer stack for protecting the multilayer stack by reducing oxidation and mechanical erosion. 9. The extreme ultraviolet reflective element as claimed in claim 8, wherein the multilayer stack includes the first reflective layer formed from silicon having a thickness from 3.5 to 4.15 nanometers and the second reflective layer formed from niobium 3.5 nanometers thick or niobium carbide 2.8 nanometers thick. 10. The extreme ultraviolet reflective element as claimed in claim 8, wherein the multilayer stack includes a barrier layer between the first reflective layer and the second reflective layer, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms, and the barrier layer for reducing the formation of silicide. 11. The extreme ultraviolet reflective element as claimed in claim 8, wherein the multilayer stack includes a barrier layer between the multilayer stack and the capping layer, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms for reducing the formation of silicide. 12. The extreme ultraviolet reflective element as claimed in claim 8, wherein the multilayer stack includes a barrier layer between the multilayer stack and the substrate, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms for reducing the formation of silicide. 13. The extreme ultraviolet reflective element as claimed in claim 8, wherein the multilayer stack includes:a barrier layer between the first reflective layer and the second reflective layer, the barrier layer formed from carbon having a thickness of 5 angstroms; anda boundary layer of silicide between the first reflective layer and the second reflective layer, the boundary layer having a reduced thickness based on the barrier layer. 14. The extreme ultraviolet reflective element as claimed in claim 8, wherein the capping layer includes the capping layer formed from ruthenium or a ruthenium alloy and an absorber layer on and over the capping layer, the absorber layer formed from chromium, tantalum, nitrides, nickel, or a combination thereof. 15. An extreme ultraviolet reflective element production system comprising:a first deposition system for depositing a multilayer stack on the substrate, the multilayer stack including a plurality of reflective layer pairs having a first reflective layer formed from silicon and a second reflective layer formed from niobium or niobium carbide for forming a Bragg reflector; anda second deposition system for forming a capping layer on the multilayer stack for protecting the multilayer stack by reducing oxidation and mechanical erosion. 16. The extreme ultraviolet reflective element production system as claimed in claim 15, wherein the first deposition system is for forming the first reflective layer from silicon having a thickness from 3.5 to 4.15 nanometers and for forming the second reflective layer from niobium 3.5 nanometers thick or niobium carbide 2.8 nanometers thick. 17. The extreme ultraviolet reflective element production system as claimed in claim 15, wherein the first deposition system is for forming a barrier layer between the first reflective layer and the second reflective layer, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms, and the barrier layer for reducing the formation of silicide. 18. The extreme ultraviolet reflective element production system as claimed in claim 15, wherein the first deposition system is for forming a barrier layer between the multilayer stack and the capping layer, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms for reducing the formation of silicide. 19. The extreme ultraviolet reflective element production system as claimed in claim 15, wherein the first deposition system is for forming a barrier layer between the multilayer stack and the substrate, the barrier layer formed from carbon having a thickness between 1 angstrom and 5 angstroms for reducing the formation of silicide. 20. The extreme ultraviolet reflective element production system as claimed in claim 15, wherein second deposition system is for forming the capping layer from ruthenium or a ruthenium alloy and an absorber layer on and over the capping layer, the absorber layer formed from chromium, tantalum, nitrides, nickel, or a combination thereof.