Patent ID: 8889550

Claim:
A lithographic method for forming in a substrate two superposed networks of conductors separated by an insulating layer, with conducting vias in the insulating layer for connecting conductors of a first network to conductors of a second network at locations where conductors of the first network cross conductors of the second network, the method comprising: forming conductors of the first network on the substrate, depositing an insulating material covering the conductors of the first network to form said insulating layer, depositing a mineral mask layer onto the insulating material, depositing a sacrificial layer and etching said sacrificial layer according to a first partial pattern, forming spacers on edges of portions of the etched sacrificial layer, the spacers leaving free regions defining a second partial pattern, removing the etched sacrificial layer to leave only the spacers, etching the mineral mask layer where said mineral mask layer is not protected by the spacers, said etching the mineral mask layer defining locations of the conductors of the second network, etching the insulating material down to a first depth, in a first etching step, etching the insulating material down to a second depth, in a second etching step, one of said first and second etching steps being done according to a pattern defined by the etched mineral mask for defining the locations of the conductors of the second network, and the other of said first and second etching steps being bounded both by openings formed in a masking layer etched by lithography and by the second partial pattern defined by the spacers, the openings defining locations for conducting vias and being bounded on at least two opposing edges by spacers, and filling voids etched into the insulating material with a conductive material flush with a surface of the insulating material without overspilling from said etched voids, said conductive material forming both the conductors of the second network and the conducting vias.