Fabricating metal interconnects for circuits on a spherical dome

Interconnecting three-dimensionally shaped integrated circuitry is a new and exciting field that has been spurred on by the need for conformal displays and detector arrays. These circuits are fabricated by first interconnecting rigid subcircuit islands made on a flat, deformable substrate. To prepare for interconnects, a patterned deformable sacrificial material is applied over the flat substrate. The substrate is then deformed, with the subcircuit islands and the sacrificial pattern on it, to a spherical surface. Following deformation, interconnect metal is evaporated and then the sacrificial material is stripped, leaving only the metal lines that interconnect the islands. Reported here is a method to fabricate a functioning X-Y matrix of interconnects and crossovers insulation. X and Y lines down to 4 mu m were fabricated and found to function on the spherically deformed substrate. Yields of line segments were as high as 98% with leakage current density between the most strained insulation being 45 +/- 10 mu A/cm(2). To optimize electrical conduction of the interconnects, the morphology of the subcircuit islands and the interconnects were investigated using optical microscopy, scanning electron microscopy, and atomic field microscopy. Detailed study shows that the rigid islands may both slip and buckle during spherical deformation. (c) 2006 The Electrochemical Society.