Stepper alignment mark structure for maintaining alignment integrity

摘要

Accurate photolighographic processing is achieved employing a stepper global alignment structure enabling formation thereon of a substantially transparent layer having a substantially planar upper surface. Embodiments include a set of global alignment marks comprising spaced apart trenches, each trench segmented into a plurality of narrow trenches spaced apart by uprights and forming a dummy topographical area of narrow trenches surrounding the set of alignment marks. The segmented trenches and the dummy topographical area effectively provide a substantially uniform topography enabling deposition of a transparent layer without steps and effective local planarization. Since the upper surface of the transparent layer is substantially planar, layers of material deposited on the transparent layer during subsequent processing also have a substantially planar upper surface, thereby enabling transmission of the signal produced by the alignment marks to the stepper with minimal distortion.