US 11,658,194 B2
Image sensors having grating structures therein that provide enhanced diffraction of incident light
Wook Lee, Suwon-si (KR); Euiyoung Song, Seoul (KR); Kwanghee Lee, Seoul (KR); Uihui Kwon, Hwaseong-si (KR); Jae Ho Kim, Seoul (KR); and Jungchak Ahn, Yongin-si (KR)
Assigned to Samsung Electronics Co., Ltd.
Filed by Samsung Electronics Co., Ltd., Suwon-si (KR)
Filed on Feb. 27, 2019, as Appl. No. 16/286,897.
Claims priority of application No. 10-2018-0104648 (KR), filed on Sep. 3, 2018.
Prior Publication US 2020/0075656 A1, Mar. 5, 2020
Int. Cl. H01L 27/146 (2006.01); G02B 5/18 (2006.01); H04N 5/378 (2011.01)
CPC H01L 27/14625 (2013.01) [G02B 5/1842 (2013.01); G02B 5/1866 (2013.01); H01L 27/14623 (2013.01); H01L 27/14643 (2013.01); H04N 5/378 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An image sensor comprising:
a semiconductor substrate of first conductivity type having a first semiconductor surface and a second semiconductor surface opposite to the first semiconductor surface;
a pixel separation structure in the semiconductor substrate, the pixel separation structure defining a pixel region;
an isolation structure in the semiconductor substrate, the isolation structure defining a light receiving region and a light blocking region, in the pixel region;
a photoelectric conversion region of second conductivity type in the light receiving region of the semiconductor substrate, said photoelectric conversion region forming a PN rectifying junction with a first portion of the semiconductor substrate;
a transfer gate electrode on the first semiconductor surface of the semiconductor substrate, in the light receiving region;
signal processing circuits on the first semiconductor surface of the semiconductor substrate, in the light blocking region;
a grating structure on the second semiconductor surface of the semiconductor substrate, in the light receiving region, the grating structure comprising grating patterns and recess regions alternately arranged; and
a blocking pattern on the second semiconductor surface of the semiconductor substrate, in the light blocking region;
wherein the semiconductor substrate includes a trench recessed from the second semiconductor surface of the semiconductor substrate in the light blocking region;
wherein a bottom surface of the trench is located at a level lower than top surfaces of the grating patterns;
wherein the grating structure and the blocking pattern are located on a same horizontal plane relative to the first semiconductor surface of the semiconductor substrate; and
wherein the blocking pattern sufficiently fills the trench, and wherein a light receiving surface of the blocking pattern that is farthest from the first semiconductor surface of the semiconductor substrate is coplanar with a light receiving portion of the second semiconductor surface of the semiconductor substrate that is farthest from the first semiconductor surface of the semiconductor substrate.