MONOLITHICALLY STACKED IMAGE SENSORS

摘要

An imaging system may be formed from multiple stacked wafers. A first wafer may include backside illuminated photodiodes, floating diffusion regions, and charge transfer gate structures. The first wafer may be bonded to a second wafer that includes pixel trunk transistors such as reset transistors, source-follower transistors, row-select transistors and associated logic circuits. The pixel trunk transistors may be formed using bottom-gate thin-body transistors. The first and second wafers may share the same backend metallization layers. The second wafer may further be bonded to a third wafer that includes digital signal processing circuits. The digital signal processing circuits may also be implemented using bottom-gate thin-body transistors. Additional metallization layers may be formed over the third wafer. The first, second, and third wafers may be fabricated using the same or different technology nodes.

主权项

1. Imaging circuitry, comprising:
a first substrate layer that includes photodiodes and floating diffusion regions; a second substrate layer that is bonded to the first substrate layer and that includes pixel transistors; and an interconnect stack formed on the second substrate layer, wherein the interconnect stack includes metal structures that are coupled to the floating diffusion regions in the first substrate layer and to the pixel transistors in the second substrate layer, and wherein the second substrate layer is interposed between the first substrate layer and the interconnect stack.