# US 2021/0242264 A1 · Light-trapping image sensors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0242264 A1 - Document ID: US20210242264A1 - Status: Published application - Kind: A1 - Application number: 16/777,060 - Filed: 2020-01-30 - Published: 2021-08-05 - Earliest claimed: 2020-01-30 - Assignees: OmniVision Technologies, Inc. - Applicants: OmniVision Technologies, Inc. - Inventors: Alireza BONAKDAR; Zhiqiang LIN; Lindsay GRANT - Web page: https://patentgrep.com/patent/US20210242264A1 ## CPC - H10F 39/8067: {Reflectors} - G02B 3/0037: {characterized by the distribution or form of lenses} - G02B 5/201: {in the form of arrays} - G02B 5/208: {for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation} - H10F 39/024: {of coatings or optical elements} - H10F 39/182: {Colour image sensors} - H10F 39/199: {Back-illuminated image sensors} - H10F 39/8053: {Colour filters} - H10F 39/8057: {Optical shielding} - H10F 39/8063: {Microlenses} - 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 - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A light-trapping image sensor includes a pixel array and a lens array. The pixel array is formed in and on a semiconductor substrate and including photosensitive pixels each including a reflective material forming a cavity around a portion of semiconductor material to at least partly trap light that has entered the cavity. The cavity has a ceiling at a light-receiving surface of the semiconductor substrate, and the ceiling forms an aperture for receiving the light into the cavity. The lens array is disposed on the pixel array. Each lens of the lens array is aligned to the aperture of a respective cavity to focus the light into the cavity through the aperture. ## Claims ### Claim 1 A light-trapping image sensor, comprising: a pixel array formed in and on a semiconductor substrate and including photosensitive pixels each including a reflective material forming a cavity around a portion of semiconductor material to at least partly trap light that has entered the cavity, the cavity having a ceiling at a light-receiving surface of the semiconductor substrate, the ceiling forming an aperture for receiving the light into the cavity; and a lens array disposed on the pixel array, each lens of the lens array being aligned to the aperture of a respective cavity to focus the light into the cavity through the aperture. ### Claim 2 (depends on 1) The image sensor of claim 1, being a backside-illuminated complementary metal oxide semiconductor image sensor, the semiconductor material being silicon. ### Claim 3 (depends on 1) The image sensor of claim 1, each lens being a microsphere. ### Claim 4 (depends on 3) The image sensor of claim 3, each microsphere being disposed directly on a respective one of the photosensitive pixels. ### Claim 5 (depends on 3) The image sensor of claim 3, the pixel array being a rectangular array, the photosensitive pixels having a pixel pitch along rows and columns of the pixel array, the diameter of each microsphere being equal to the pixel pitch. ### Claim 6 (depends on 3) The image sensor of claim 3, being a color image sensor further comprising a color filter array disposed above the lens array to spectrally filter the light before being focused by the microspheres, the color filter array being an array of identical color filter groups each including a plurality of color filters configured to transmit light in a respective plurality of spectral ranges. ### Claim 7 (depends on 3) The image sensor of claim 3, being a color image sensor, each microsphere being formed from a color-filtering material to spectrally filter the light while focusing the light, the lens array being an array of identical microsphere groups each including a plurality of microspheres configured to selectively transmit light in a respective plurality of spectral ranges. ### Claim 8 (depends on 7) The image sensor of claim 7, the semiconductor material being silicon, one of the spectral ranges including near-infrared wavelengths. ### Claim 9 (depends on 1) The image sensor of claim 1, each lens being a plano-convex microlens with a convex surface for receiving the light into the plano-convex microlens. ### Claim 10 (depends on 9) The image sensor of claim 9, the lens array having less than 100% fill factor such that each plano-convex microlens is separated from each of its adjacent plano-convex microlenses by a non-zero distance. ### Claim 11 (depends on 9) The image sensor of claim 9, focal point of each plano-convex microlens being at the aperture of the corresponding cavity. ### Claim 12 (depends on 9) The image sensor of claim 9, being a color image sensor further comprising a color filter array disposed between the pixel array and the lens array, the color filter array being an array of identical color filter groups each including a plurality of color filters configured to transmit light in a respective plurality of spectral ranges. ### Claim 13 (depends on 12) The image sensor of claim 12, the semiconductor material being silicon, one of the spectral ranges including near-infrared wavelengths. ### Claim 14 (depends on 1) The image sensor of claim 1, the ceiling including metal. ### Claim 15 (depends on 1) The image sensor of claim 1, each cavity further having a floor, and sidewalls spanning between the floor and the ceiling, wherein, for each cavity, the floor includes a respective metal contact for conducting a photo-generated charge out of the cavity. ### Claim 16 (depends on 1) The image sensor of claim 1, each cavity further having a floor, and sidewalls spanning between the floor and the ceiling, wherein, for each cavity, the sidewalls include deep trench isolation. ### Claim 17 (depends on 16) The image sensor of claim 16, the deep trench isolation including: metal; and an oxide layer lining the metal. ### Claim 18 (depends on 16) The image sensor of claim 16, the sidewalls being shared between adjacent photosensitive pixels such that, where the deep trench isolation is between adjacent first and second photosensitive pixels, the metal or low-index-of-refraction dielectric of the deep trench isolation is lined by a first oxide layer facing the first photosensitive pixel and a second oxide layer facing the second photosensitive pixel. ### Claim 19 (depends on 1) The image sensor of claim 1, each cavity further having a floor, and sidewalls spanning between the floor and the ceiling, wherein, for each cavity, one or both of the floor and the ceiling are at least partly jagged. ### Claim 20 (depends on 19) The image sensor of claim 19, jagged portions of the one or both of the floor and ceiling having pyramids extending into the semiconductor material enclosed by the cavity.