US Patent 7491620 Method and structures for indexing dice

A method of indexing a plurality of dice obtained from a material wafer comprising a plurality of stacked material layers, each die being obtained in a respective die position in the wafer, the method including providing a visible index on each die indicative of the respective die position, wherein providing the visible index on each die includes: forming in a first material layer of the die a reference structure adapted to defining a mapping of the wafer; and forming in a second material layer of the die a marker associated with the reference structure, a position of the marker with respect to the reference structure being adapted to provide an indication of the die position in the wafer.