This Small Business Innovation Research Phase I project will demonstrate a novel z-axis connector technology using microporous materials. In this project, aluminum plates, 0.05-0.5 mm thick, would be anodized to form microporous alumina with densely packed, straight vertical (z-axis) pores of submicron diameters, and length to diameter ratios exceeding 500. When the pores are plated up with metals, the plates would have very high resistivity along the plane of the plate, and very low resistivity through the plate thickness, thereby enabling reliable z-axis connections between 2 planar circuit arrays, on sub-micron circuit elements. Such a mass connector between 2 semiconductor circuits would scale to large areas, provide micron-scale connections, and require no precision alignment between the connected circuits and would be low cost. With development in microporous alumina and silicon, it may be possible to form z-axis connections between microcircuits in a growth/deposition process, forming the connection directly on microcircuits without mechanical placement steps between circuits. Anticipated benefits include: (1) the connection of dense arrays of microsensors, such as pressure, temperature or light sensor `pixels`, to a rear read-out chip containing signal processing, A-D conversion, etc. (`smart pixels`); (2) vertically stacked (z-stacked) VLSI circuits, such as memories, or processor and cache stacks of very high density; and (3) large flat panel displays, for example by connecting thin film transistor arrays to LCD active matrix pixels reliably over a large area.
