Einzeltreffer — DigiBib

The present disclosure relates to a CMOS image sensor, and an associated method of formation. In some embodiments, the CMOS image sensor comprises a substrate and a transfer gate disposed from a front-side surface of the substrate. The CMOS image sensor further comprises a photo detecting column disposed at one side of the transfer gate within the substrate. The photo detecting column comprises a doped sensing layer comprising one or more recessed portions along a circumference of the doped sensing layer in parallel to the front-side surface of the substrate. By forming the photo detecting column with recessed portions, a junction interface is enlarged compared to a previous p-n junction interface without recessed portions, and thus a full well capacity of the photodiode structure is improved.

Titel:	CMOS IMAGE SENSOR HAVING INDENTED PHOTODIODE STRUCTURE
Link:	View record in USPTO Patent Applications (Volltext)
Veröffentlichung:	2024
Medientyp:	Patent
Sonstiges:	Nachgewiesen in: USPTO Patent Applications Sprachen: English Document Number: 20240063234 Publication Date: February 22, 2024 Appl. No: 18/500357 Application Filed: November 02, 2023 Claim: 1. A method of forming an image sensor, comprising: forming a transfer gate over a substrate, wherein the substrate is doped with a first doping type; forming a floating diffusion region within the substrate; forming a masking layer over the substrate, the masking layer having a circumference including recessed portions that are symmetrically distributed along an extended line of centers of the transfer gate and the floating diffusion region; and with the masking layer in place, performing a plurality of implantation processes to form a photo detecting column within the substrate at one side of the transfer gate opposing to the floating diffusion region; wherein the photo detecting column and the substrate are in contact with each other at a junction interface and configured as a photodiode structure to convert radiation that enters the substrate into an electrical signal. Claim: 2. The method of claim 1, further comprising: forming a back-end-of-the-line (BEOL) metallization stack on a front-side of the substrate, wherein the BEOL metallization stack comprises a plurality of metal interconnect layers within one or more inter-level dielectric layers. Claim: 3. The method of claim 1, wherein the photo detecting column is formed with one or more recessed portions extending upwardly to a front-side surface of the substrate. Claim: 4. The method of claim 1, wherein the plurality of implantation processes further comprises: forming a deep doped layer with a second doping type different than the first doping type; and forming a doped sensing layer with the second doping type over the deep doped layer; forming a pinning layer with the first doping type over the doped sensing layer. Claim: 5. The method of claim 4, wherein the pinning layer is formed with a sidewall surface vertically aligned with that of the doped sensing layer. Claim: 6. The method of claim 4, wherein the deep doped layer has a doping concentration smaller than that of the doped sensing layer. Claim: 7. The method of claim 1, wherein a top surface of the photo detecting column has a concave polygon shape. Claim: 8. A method for forming an image sensor, the method comprising: forming a transfer gate over a substrate, wherein the substrate is doped with a first doping type; forming a floating diffusion region within the substrate on one side of the transfer gate; and forming a photo detecting column within the substrate on another side of the transfer gate opposite to the floating diffusion region; wherein the photo detecting column has a circumference with recessed portions extending vertically from top to bottom that are symmetrically distributed along an extended line of centers of the transfer gate and the floating diffusion region. Claim: 9. The method of claim 8, wherein the forming of the photo detecting column further comprises: forming a deep doped layer with a second doping type different than the first doping type; forming a doped sensing layer with the second doping type over the deep doped layer; and forming a pinning layer with the first doping type over the doped sensing layer. Claim: 10. The method of claim 9, wherein the deep doped layer is formed with a thickness about two times greater than that of the doped sensing layer. Claim: 11. The method of claim 9, wherein the deep doped layer is formed with a sidewall surface vertically aligned with that of the doped sensing layer. Claim: 12. The method of claim 8, further comprising: forming a back-end-of-line (BEOL) metallization stack on a front-side of the substrate and comprising a plurality of metal interconnect layers within one or more inter-level dielectric layers. Claim: 13. The method of claim 8, further comprising: forming a color filter on a back-side of the substrate opposite to a front-side of the substrate and in a grid structure, wherein the color filter overlies the photo detecting column. Claim: 14. A method for forming a complementary metal-oxide-semiconductor (CMOS) image sensor, the method comprising: forming a transfer gate over a substrate; forming a floating diffusion region within the substrate; and forming a photo detecting column within the substrate on another side of the transfer gate opposite to the floating diffusion region; wherein the photo detecting column has a circumference with one or more recessed portions extending upwardly to a front-side surface of the substrate. Claim: 15. The method of claim 14, wherein the transfer gate has a triangular shape. Claim: 16. The method of claim 14, wherein a top surface of the photo detecting column has a concave polygon shape. Claim: 17. The method of claim 14, wherein the photo detecting column is formed with one or more recessed portions extending upwardly to a front-side surface of the substrate. Claim: 18. The method of claim 14, further comprising: forming a back-end-of-the-line (BEOL) metallization stack on a front-side of the substrate, wherein the BEOL metallization stack comprises a plurality of metal interconnect layers within one or more inter-level dielectric layers. Claim: 19. The method of claim 14, wherein the forming of the photo detecting column further comprises: forming a deep doped layer with a second doping type different than a first doping type; forming a doped sensing layer with the second doping type over the deep doped layer; and forming a pinning layer with the first doping type over the doped sensing layer. Claim: 20. The method of claim 19, wherein the deep doped layer has a thickness about two times greater than that of the doped sensing layer. Current International Class: 01

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CMOS IMAGE SENSOR HAVING INDENTED PHOTODIODE STRUCTURE