US 11,710,752 B2
Flicker-mitigating pixel-array substrate
Yuanliang Liu, San Jose, CA (US); Bill Phan, San Jose, CA (US); Duli Mao, Sunnyvale, CA (US); and Hui Zang, San Jose, CA (US)
Assigned to OmniVision Technologies, Inc., Santa Clara, CA (US)
Filed by OmniVision Technologies, Inc., Santa Clara, CA (US)
Filed on Dec. 10, 2020, as Appl. No. 17/118,252.
Prior Publication US 2022/0190019 A1, Jun. 16, 2022
Int. Cl. H01L 27/146 (2006.01)
CPC H01L 27/14623 (2013.01) [H01L 27/1463 (2013.01); H01L 27/14605 (2013.01); H01L 27/14685 (2013.01); H01L 27/14621 (2013.01); H01L 27/14627 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A flicker-mitigating pixel-array substrate comprising:
a semiconductor substrate including four large-photodiode regions forming a two-by-two array, and a small-photodiode region located at a center of the two-by-two array, a back surface of the semiconductor substrate forming a trench surrounding the small-photodiode region in a cross-sectional plane parallel to a small back-surface region of the back surface above the small-photodiode region;
a metal annulus at least partially filling the trench, surrounding the small-photodiode region in the cross-sectional plane, extending above the back surface;
a monolithic metal structure including (i) a metal annulus at least partially filling the trench, surrounding the small-photodiode region in the cross-sectional plane and the small back-surface region, extending above the back surface, and (ii) a metal layer covering the small back-surface region; and
a color filter surrounded by the metal annulus and disposed on both the metal annulus and the metal layer.