Coupled 2D-arrays of Josephson junctions

As a first step toward fabricating a truly-3D Josephson junction array we have developed a fabrication technology to stack 2D-arrays of Josephson junctions on top of ead other. The coupling between the array is capacitive and/or inductive. We describe in detail the fabrication technique which consists of a four-layers process including electron beam lithography with alignment. Fabrication efforts are especially devoted to arrays with large junctions (0.5 mu m(2)) for studying interaction of vortices through inductive coupling. A similar fabrication technology may allow us to study the interaction of vortices in one array with charges in the other array. The conditions for efficient coupling are discussed in both cases.