US 11,810,987 B2
Radiation sensor element and method
Antti Haarahiltunen, Perttula (FI); Juha Heinonen, Espoo (FI); Mikko Juntunen, Kirkkonummi (FI); Chiara Modanese, Espoo (FI); Toni Pasanen, Espoo (FI); Hele Savin, Espoo (FI); and Ville Vähänissi, Vantaa (FI)
Assigned to ELFYS OY, Espoo (FI)
Appl. No. 17/614,884
Filed by ELFYS OY, Espoo (FI)
PCT Filed May 26, 2020, PCT No. PCT/FI2020/050352
§ 371(c)(1), (2) Date Nov. 29, 2021,
PCT Pub. No. WO2020/240087, PCT Pub. Date Dec. 3, 2020.
Claims priority of application No. 20195457 (FI), filed on May 31, 2019.
Prior Publication US 2022/0216354 A1, Jul. 7, 2022
Int. Cl. G01T 1/20 (2006.01); H01L 31/0236 (2006.01); G01T 1/24 (2006.01); H01L 27/146 (2006.01); H01L 31/115 (2006.01)
CPC H01L 31/02363 (2013.01) [G01T 1/20183 (2020.05); G01T 1/24 (2013.01); H01L 27/1461 (2013.01); H01L 27/14676 (2013.01); H01L 31/115 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A radiation sensor element comprising a semiconductor substrate, having bulk majority charge carriers of a first polarity, a bulk refractive index, a front surface, defining a front side of the semiconductor substrate, and a back surface, arranged opposite the front surface and extending substantially along a base plane;
the radiation sensor element comprising a plurality of pixel portions, each pixel portion of the plurality of pixel portions comprising a collection region on the back surface for collecting free charge carriers of a second polarity opposite in sign to the first polarity;
wherein each pixel portion of the plurality of pixel portions comprises a textured region on the front surface, the textured region comprising high aspect ratio nanostructures, extending substantially along a thickness direction perpendicular to the base plane and forming an optical conversion layer, having an effective refractive index gradually changing towards the bulk refractive index to reduce reflection of light emitted by a scintillator and incident on said pixel portion from the front side of the semiconductor substrate;
the radiation sensor element comprises an intermediate portion between two pixel portions of the plurality of pixel portions, the intermediate portion comprising an intermediate region on the front surface with a root mean square, RMS, roughness lower than a RMS roughness of a textured region of either of the two pixel portions; and
the radiation sensor element comprises the scintillator coupled to the intermediate region.