Omnivision Proposes Adding Shield Bumps to Pixel Level Interconnect

Omnivision patent application US20180097030 "Stacked image sensor with shield bumps between interconnects" by Sohei Manabe, Keiji Mabuchi, Takayuki Goto, Vincent Venezia, Boyd Albert Fowler, and Eric A. G. Webster reduces coupling in pixel level interconnected stacked sensor:

"One of the challenges presented with conventional stacked image sensors is the unwanted capacitive coupling that exists between the adjacent interconnection lines between the first and second dies of the stacked image sensors that connect the photodiodes to the pixel support circuits. The capacitive coupling between the adjacent interconnection lines can cause interference or result in other unwanted consequences between adjacent interconnection lines when reading out image data from the photodiodes."

"As such, there are also shield bumps 520 disposed between adjacent interconnection lines 518 along each of the diagonals A-A′ and/or B-B′ of the pixel array of stacked imaging system 500 in accordance with the teachings of the present invention. As such, when every other pixel cell in two rows of the pixel array included in stacked imaging system 500 are read out at a time, there is a shield bump 520 disposed the corresponding interconnect lines 518 in accordance with the teachings of the present invention. With a shield bump 520 disposed between adjacent interconnection lines 518, the coupling capacitance is eliminated to reduce unwanted interference, crosstalk, and the like, during readouts of stacked image sensor 500 in accordance with the teachings of the present invention."