High-Z structure and method for co-alignment of mixed optical and electron beam lithographic fabrication levels

A structure for aligning a first set of features of a fabrication level of an integrated circuit chip to an electron beam alignment target. The structure including a first trench in a semiconductor substrate, the first trench extending from a top surface of the substrate into the substrate a first distance; an electron back-scattering layer in a bottom of the first trench; a dielectric capping layer in the trench over the back-scattering layer; and a second trench in the substrate, the second trench extending from the top surface of the substrate into the substrate a second distance, the second distance less than the first distance.