Blazed grating spectral purity filter and methods of making such a filter

A novel blazed grating spectral filter disclosed herein includes a multilayer stack of materials that is formed on a wedge-shaped substrate wherein the upper surface of the substrate is oriented at an angle relative the bottom surface of the substrate and wherein the angle corresponds to the blaze angle of the blazed grating filter. Various methods of forming such a filter are also disclosed such as, for example, performing a planarization process in a CMP tool to define the wedge-shaped substrate, thereafter forming the multilayer stack of materials above the upper planarized surface of the substrate and etching recesses into the multilayer stack.