Patent ID: 7820525

Claim:
A method for making a hybrid image sensor utilizing a wafer-to-wafer bonding technique comprising: A) utilizing a first lithographic process to fabricate on a first wafer at least one readout circuit, each of said at least one readout circuit comprising an array of pixel readout circuits and also comprising supporting circuits, each pixel readout circuit in said array of readout circuits comprising at least one pixel conductive element, B) including, during the first lithographic process the deposition of a first bonding agent layer covering the at least one readout circuit, C) including in each pixel of the array of pixel readout circuits at least one lithographically produced conductive interconnect passing through said first bonding agent layer to provide electrical communication to said at least one pixel conductive element, all of the conductive interconnects in the array of pixel readout circuits defining a set of pixel readout circuit interconnects, D) utilizing a second lithographic process to fabricate at least one array of pixel photodiodes of on a second substrate wafer to define a photodiode wafer and an array of pixel photodiodes, each pixel photodiode in the array of pixel photodiodes defining at least a photo-detector structure and a conductive pixel pad, E) including, during the second lithographic process the deposition of a second bonding agent layer covering the array of pixel photodiodes, F) including, during the second lithographic process in each pixel photodiode in the array of pixel photodiodes at least one lithographically produced conductive interconnect passing through said second bonding agent layer to provide electrical communication to the conductive pixel pad of the pixel photodiode, all of the conductive interconnect in the array of pixel photodiodes defining a set of pixel photodiode interconnects, G) fabricating on each of the photodiode wafer and the readout circuit wafer at least one alignment feature adapted to permit alignment of the set of pixel photodiode interconnects on the photodiode wafer to the set of pixel readout circuit interconnects on the readout circuit wafer to an accuracy of less than 2 microns, and H) positioning one of the two wafers together face to face so as to align the set of photodiode interconnects to the set of pixel readout circuit interconnects to an accuracy of less than 2 microns so as to permit the bonding agent to bond the two wafers together providing electrical contact between the readout circuit interconnects and the photodiode interconnects so as to electrically connect each pixel readout circuit on the readout circuit wafer to a pixel photodiode on the photodiode wafer.