Stacked image sensor capable of simultaneous integration of electrons and holes
Various embodiments of the present technology may comprise methods and apparatus for an image sensor capable of simultaneous integration of electrons and holes. According to an exemplary embodiment, the image sensor comprises a backside-illuminated hybrid bonded stacked chip image senor comprising a pixel circuit array, and each pixel circuit comprising a charge storage capacitor oriented in a vertical direction in a deep trench isolation region. Both the electrons and holes are integrated (collected) using a global shutter operation, and the charge storage capacitor is used for storing a signal generated by the holes.
1. A solid-state stacked chip image sensor, comprising:
an array of pixel circuits, each pixel circuit comprising:
an epitaxial layer comprising:
a pixel body having a first major surface and an opposing second major surface, and comprising:
a photodiode;
a floating body region;
a p+ type doped region along opposing sidewalls and adjacent to the second major surface of the pixel body;
a trench region extending from the first major surface to the second major surface of the epitaxial layer, wherein the trench region comprises:
an oxide layer deposited on opposing vertical sidewalls of the trench region; and
a center portion disposed between the opposing oxide layers, wherein the center portion comprises an electrically conductive material and is connected to a ground potential;
a charge transfer structure disposed at least partially within the epitaxial layer, wherein the charge transfer structure comprises a drain and is configured to divert electron charge from the photodiode to the drain; and
a readout circuit connected to the floating body region;
wherein each pixel circuit is formed across a plurality of chips.
2. The solid-state stacked chip image sensor according to claim 1 , wherein the solid-state image sensor comprises a first chip stacked vertically with a second chip.
3. The solid-state stacked chip image sensor according to claim 2 , wherein:
the first chip comprises the epitaxial layer and the charge transfer structure; and
the second chip comprises the readout circuit.
4. The solid-state stacked chip image sensor according to claim 2 , wherein the first chip and the second chip are bonded together with a hybrid bond pad; and wherein the hybrid bond pad is:
disposed between the first major surface of the epitaxial layer and the second chip; and
substantially overlaps the photodiode.
5. The solid-state stacked chip image sensor according to claim 1 , where each pixel further comprises a color filter and a micro lens disposed adjacent to the second major surface of the epitaxial layer.
6. The solid-state stacked chip image sensor according to claim 1 , wherein the image sensor is configured as a backside illuminated image sensor.
7. The solid-state stacked chip image sensor according to claim 1 , wherein the readout circuit comprises:
a source follower transistor connected to the floating body region;
a feedback capacitor connected to the source follower transistor;
a row select transistor connected to a source terminal of the source follower transistor and responsive to a row select signal; and
a pre-charge capacitor connected to the floating body node and responsive to a pre-charge signal.