US 11,698,296 B2
Light sensor using pixel optical diffraction gratings having different pitches
Stephane Monfray, Eybens (FR); Olivier Le Neel, Saint Martin d Uriage (FR); and Frederic Boeuf, Le Versoud (FR)
Assigned to STMicroelectronics (Crolles 2) SAS, Crolles (FR); and STMicroelectronics SA, Montrouge (FR)
Filed by STMicroelectronics (Crolles 2) SAS, Crolles (FR); and STMicroelectronics SA, Montrouge (FR)
Filed on Sep. 17, 2020, as Appl. No. 17/24,202.
Claims priority of application No. 1910593 (FR), filed on Sep. 25, 2019.
Prior Publication US 2021/0088378 A1, Mar. 25, 2021
Int. Cl. G01J 1/04 (2006.01); H01L 31/0232 (2014.01); G01J 1/44 (2006.01); G02B 5/18 (2006.01); H01L 31/101 (2006.01)
CPC G01J 1/0411 (2013.01) [G01J 1/44 (2013.01); G02B 5/1828 (2013.01); G02B 5/1857 (2013.01); H01L 31/02327 (2013.01); H01L 31/1013 (2013.01); G01J 2001/444 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A light sensor, comprising:
a semiconductor substrate; and
a plurality of pixels, wherein each pixel comprises:
a photoconversion zone extending in the semiconductor substrate between a front face and a back face of the semiconductor substrate;
an optical diffraction grating positioned over the back face of the semiconductor substrate and facing the photoconversion zone of the pixel; and
a wall configured to be absorbent at operating wavelengths of the sensor, said wall positioned to laterally surround the optical diffraction grating of the pixel and extend heightwise from the back face of the semiconductor substrate at least up to a level of the optical diffraction grating of the pixel;
wherein the optical diffraction grating of one pixel of said plurality of pixels and the optical diffraction grating of another pixel of said plurality of pixels have different pitches.