# US 2025/0098358 A1 · Image sensing device including source follower transistor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0098358 A1 - Document ID: US20250098358A1 - Status: Published application - Kind: A1 - Application number: 18/623,316 - Filed: 2024-04-01 - Published: 2025-03-20 - Earliest claimed: 2023-09-14 - Assignees: SK hynix Inc. - Applicants: SK hynix Inc. - Inventors: Young Gyu YOU; Dong Joo YANG - Web page: https://patentgrep.com/patent/US20250098358A1 ## CPC - H10F 39/813: {Electronic components shared by multiple pixels, e.g. one amplifier shared by two pixels} - H04N 25/77: Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components - H10F 39/803: {Pixels having integrated switching, control, storage or amplification elements} - H10F 39/8037: {the integrated elements comprising a transistor} - H10F 39/807: {Pixel isolation structures} - H10F 39/811: {Interconnections} - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image sensing device including a source follower transistor is disclosed. The image sensing device includes first and second photoelectric conversion elements that supported by the semiconductor substrate and are spaced apart from each other, a first pixel isolation structure recessed from the second surface and configured to surround the first and second photoelectric conversion elements; second and third pixel isolation structures disposed between the first photoelectric conversion element and the second photoelectric conversion element and spaced apart from each other; and a source follower transistor supported by the semiconductor substrate and configured to include a gate disposed on the second surface in at least a portion of a gap region between the second pixel isolation structure and the third pixel isolation structure. ## Claims ### Claim 1 An image sensing device comprising: a semiconductor substrate configured to include a first surface upon which light is incident from a scene and a second surface facing or opposite to the first surface; first and second photoelectric conversion elements that are supported by the semiconductor substrate and are spaced apart from each other, each photoelectric conversion element configured to receive incident light and generate photocharges by sensing the received incident light; a first pixel isolation structure recessed from the second surface and configured to surround the first and second photoelectric conversion elements; second and third pixel isolation structures disposed between the first photoelectric conversion element and the second photoelectric conversion element and spaced apart from each other; and a source follower transistor supported by the semiconductor substrate and configured to include a gate disposed on the second surface in at least a portion of a gap region between the second pixel isolation structure and the third pixel isolation structure. ### Claim 2 (depends on 1) The image sensing device according to claim 1, wherein: the gate of the source follower transistor is disposed to overlap at least one of the first and second photoelectric conversion elements. ### Claim 3 (depends on 1) The image sensing device according to claim 1, wherein: each of the second pixel isolation structure and the third pixel isolation structure is in contact with the first pixel isolation structure. ### Claim 4 (depends on 1) The image sensing device according to claim 1, further comprising: a fourth pixel isolation structure disposed in the gap region. ### Claim 5 (depends on 1) The image sensing device according to claim 1, further comprising: a first floating diffusion region configured to store photocharges that are generated by the first photoelectric conversion element in response to the incident light; and a second floating diffusion region configured to store photocharges that are generated by the second photoelectric conversion element in response to the incident light. ### Claim 6 (depends on 5) The image sensing device according to claim 5, further comprising: a first transfer transistor having a first terminal electrically connected to the first photoelectric conversion element and a second terminal electrically connected to the first floating diffusion region; and a second transfer transistor having a first terminal electrically connected to the second photoelectric conversion element and a second terminal electrically connected to the second floating diffusion region. ### Claim 7 (depends on 6) The image sensing device according to claim 6, wherein: the gate of the first transfer transistor overlaps the first photoelectric conversion element, and is disposed on the second surface of the semiconductor substrate to be spaced apart from the gate of the source follower transistor; and the gate of the second transfer transistor overlaps the second photoelectric conversion element, and is disposed on the second surface of the semiconductor substrate to be spaced apart from the gate of the source follower transistor. ### Claim 8 (depends on 6) The image sensing device according to claim 6, wherein: the gate of the first transfer transistor includes a structure that is recessed from the second surface toward an inside of the semiconductor substrate, and is disposed within the semiconductor substrate to be spaced apart from the first floating diffusion region; and the gate of the second transfer transistor includes a structure that is recessed from the second surface toward the inside of the semiconductor substrate, and is disposed within the semiconductor substrate to be spaced apart from the second floating diffusion region. ### Claim 9 (depends on 5) The image sensing device according to claim 5, further comprising: a reset transistor supported by the semiconductor substrate and structured to include a gate that overlaps the first photoelectric conversion element, and is disposed on the second surface of the semiconductor substrate to be spaced apart from the gate of the source follower transistor, wherein the reset transistor is configured to drain photocharges stored in the first and the second floating diffusion regions. ### Claim 10 (depends on 1) The image sensing device according to claim 1, further comprising: a selection transistor supported by the semiconductor substrate and structured to include a gate that overlaps the second photoelectric conversion element, and is disposed on the second surface of the semiconductor substrate to be spaced apart from the gate of the source follower transistor, wherein the selection transistor outputs an electrical signal having a voltage level corresponding to the photocharges generated by the first or second photoelectric conversion element. ### Claim 11 (depends on 1) The image sensing device according to claim 1, further comprising: a drain transistor supported by the semiconductor substrate and structured to include a gate that overlaps the first photoelectric conversion element, and is disposed on the second surface of the semiconductor substrate to be spaced apart from a gate of the source follower transistor, wherein the photocharges generated by the first or second photoelectric conversion element are reset by the drain transistor. ### Claim 12 (depends on 6) The image sensing device according to claim 6, further comprising: a dual conversion gain (DCG) transistor supported by the semiconductor substrate and structured to include a gate that overlaps the first photoelectric conversion element, and is disposed on the second surface of the semiconductor substrate to be spaced apart from the gate of the source follower transistor, wherein the DCG transistor changes a capacitance of at least one of the first and the second floating diffusion regions. ### Claim 13 (depends on 5) The image sensing device according to claim 5, further including: a metal interconnect layer configured to contact each of the first floating diffusion region and the second floating diffusion region while being located outside the semiconductor substrate, wherein the metal interconnect layer electrically connects the first floating diffusion region and the second floating diffusion region to each other. ### Claim 14 An image sensing device comprising: a semiconductor substrate configured to include a first surface upon which light is incident and a second surface facing or opposite to the first surface; a first photoelectric conversion element supported by the semiconductor substrate and configured to generate photocharges in response to the incident light; a second photoelectric conversion element supported by the semiconductor substrate and spaced apart from the first photoelectric conversion element, and configured to generate photocharges in response to the incident light; and a source follower transistor supported by the semiconductor substrate and structured to include a gate disposed in a gap region between the first photoelectric conversion element and the second photoelectric conversion element, wherein the gate of the source follower transistor overlaps at least a portion of each of the first photoelectric conversion element and the second photoelectric conversion element that are arranged in a first direction perpendicular to the second surface. ### Claim 15 (depends on 14) The image sensing device according to claim 14, further comprising: a first transfer transistor supported by the semiconductor substrate and structured to include a gat that overlaps the first photoelectric conversion element in the first direction and is disposed on the second surface of the semiconductor substrate to be spaced apart from the gate of the source follower transistor; and a second transfer transistor supported by the semiconductor substrate and structured to include a gate that overlaps the second photoelectric conversion element in the first direction and is disposed on the second surface of the semiconductor substrate to be spaced apart from both the gate of the source follower transistor and the gate of the first transfer transistor. ### Claim 16 (depends on 15) The image sensing device according to claim 15, further comprising: a floating diffusion region supported by the semiconductor substrate within a space between the gate of the first transfer transistor and the gate of the second transfer transistor, and arranged adjacent to the second surface of the semiconductor substrate. ### Claim 17 (depends on 15) The image sensing device according to claim 15, further comprising: a first floating diffusion region spaced apart from the gate of the first transfer transistor, disposed within the semiconductor substrate, and adjacent to the second surface; and a second floating diffusion region spaced apart from the gate of the second transfer transistor, disposed within the semiconductor substrate, and adjacent to the second surface. ### Claim 18 (depends on 17) The image sensing device according to claim 17, further comprising: a metal interconnect layer configured to contact each of the first floating diffusion region and the second floating diffusion region while being located outside the semiconductor substrate, wherein the metal interconnect layer electrically connects the first floating diffusion region and the second floating diffusion region to each other. ### Claim 19 (depends on 14) The image sensing device according to claim 14, further comprising: a pixel isolation structure recessed from the first surface of the semiconductor substrate corresponding to the gap region toward an inside of the semiconductor substrate. ### Claim 20 (depends on 16) The image sensing device according to claim 16, wherein the first photoelectric conversion element and the second photoelectric conversion element are configured to share the floating diffusion region.