Patent ID: 7385272

Claim:
A method of fabricating an image sensor integrated circuit having a plurality of photodetectors using energy of photons reaching the plurality of photodetectors to excite electrons; a plurality of nodes, each of the plurality of photodetectors having a corresponding node of the plurality of nodes; a plurality of transfer devices each with a first terminal coupled to one of the plurality of photodetectors, a second terminal coupled to the corresponding node, and a control terminal causing a transfer of the electrons from the first terminal to the second terminal in response to receiving a control signal of sufficient value; a plurality of reset devices, each of the plurality of nodes having a corresponding reset device of the plurality of reset devices, and said each of the plurality of nodes is reset when the corresponding reset device is active; and a plurality of signal devices coupling the plurality of nodes to row and column circuitry; the method comprising: forming a plurality of oxide structures shaped to isolate adjacent photodetectors from each other; implanting a first n-type region for each of the plurality of photodetectors, the first n-type region receiving the electrons excited by the energy of the photons, the first n-type region at a first depth range in the integrated circuit; implanting a second n-type region for each of the plurality of photodetectors, the second n-type region at a second depth range wherein the first depth range includes depths deeper than the second depth range, adjacent to the first n-type region and at least part of the second n-type region positioned between the first n-type region and an oxide structure of the plurality of oxide structures, and receiving the electrons from the first n-type region; depositing the control terminal for each of the plurality of transfer devices at least partly above the second n-type region of the plurality of photodetectors; implanting the plurality of nodes, wherein each of the plurality of photodetectors has a corresponding node of the plurality of nodes where the electrons are measured prior to removal; and implanting at least one n+ terminal for each of the plurality of transfer devices, wherein said method forms row and column circuitry on the image sensor integrated circuit accessing the plurality of nodes.