Stacked photo sensor assembly with pixel level interconnect
AssigneeFacebook Technologies, LLC
InventorXinqiao Liu
Life of this patent
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Abstract
Embodiments relate to a stacked photo sensor assembly where two substrates that are stacked vertically. The two substrates are connected via interconnects at a pixel level to provide a signal from a photodiode at a first substrate to circuitry on a second substrate. The circuitry on the second substrate performs operations that were conventionally performed on first substrate. By stacking the first and second substrates, the photo sensor assembly can be made more compact while increasing or at least retaining the photodiode fill factor of the photo sensor assembly.
Claims14
A pixel of a photo sensor comprising:
- a portion of a first substrate comprising:
- a photodiode for detecting light, and
- a diffusion well associated with the photodiode to store charge from the photodiode, an amount of charge stored in the diffusion well dependent on duration and intensity of the light incident on the photodiode;
- a portion of a second substrate having a circuit for processing a signal from the first substrate;
- and
- a pixel level interconnect that connects the second well of the first substrate to the circuit of the second substrate to carry the signal from the diffusion well to the circuit.
A method for operating a photo sensor, the method comprising:
- detecting light by a photodiode in a first substrate;
- storing charge from the photodiode by a diffusion well in the first substrate, the charge dependent on duration and intensity of light incident on the photodiode;
- generating a signal in the first substrate representing the charge stored in the diffusion well;
- sending the signal from the first substrate to the second substrate by a pixel-level interconnect that connects the diffusion well of the first substrate to a circuit of a second substrate;
- and
- processing the signal by the circuit in the second substrate.
Dependencies are inferred from the claim text.