Corrosion resistant imager

Abstract

A radiation imager is disclosed that is resistant to degradation due to moisture by either contact pad corrosion, guard ring corrosion or by photodiode leakage. A contact pad of a large area imager is disclosed that is formed into three distinct and electrically connected regions. The resulting structure of the contact pad regions forms reliable contact that is resistant to corrosion damage. Also disclosed is a data line of an imager, or a display, the resistance of which is reduced by patterning an aluminum (Al) line on top of a transistor island structure, with the formed data line preferably being encapsulated. In addition, a guard ring having first and second regions and photosensitive element are disclosed. The second region comprises an electrical contact between ITO and underlying metal and a second tier which acts as a moisture barrier and is preferably disposed at the corner of the guard ring and separated from the contact pads of the imager in such a manner as to minimize corrosion. The photosensitive element has a multitier passivation layer disposed between the top contact layer and an amorphous silicon photosensor island except for a selected contact area on the top surface of the photosensor island, where the top contact layer is in electrical contact with the amorphous silicon material of the photosensor island. The passivation layer includes a first tier inorganic barrier layer which is disposed at least over the sidewalls of the photosensor island.