US 12,464,837 B2
High dynamic range, backside-illuminated, low crosstalk image sensor with walls on backside surface to isolate photodiodes
Hui Zang, San Jose, CA (US); and Gang Chen, San Jose, CA (US)
Assigned to OmniVision Technologies, Inc., Santa Clara, CA (US)
Filed by OmniVision Technologies, Inc., Santa Clara, CA (US)
Filed on Feb. 3, 2022, as Appl. No. 17/592,370.
Prior Publication US 2023/0282671 A1, Sep. 7, 2023
Int. Cl. H10F 39/12 (2025.01); H10F 39/00 (2025.01); H10F 39/18 (2025.01)
CPC H10F 39/199 (2025.01) [H10F 39/024 (2025.01); H10F 39/182 (2025.01); H10F 39/8053 (2025.01); H10F 39/807 (2025.01); H10F 39/811 (2025.01)] 18 Claims
OG exemplary drawing
 
1. A backside-illuminated image sensor comprising:
a semiconductor substrate;
a plurality of photodiodes arranged in an array formed in the semiconductor substrate;
a first dielectric layer disposed on a backside of the semiconductor substrate, the first dielectric layer having a plurality of openings aligning with each of the plurality of photodiodes; and
a metal grid disposed on the first dielectric layer, the metal grid defining a plurality of apertures aligning with the plurality of photodiodes;
a plurality of isolation structures, each of the plurality of isolation structures isolating a photodiode from other of the plurality of photodiodes and comprising:
a trench formed in the backside of the semiconductor substrate,
an oxide-based liner disposed in the trench, and lining surfaces of the trench;
a high-k material layer disposed in the trench on the oxide-based liner and on the backside of the semiconductor substrate;
a second dielectric layer disposed in the trench on the high-k material layer; and
a dielectric filling material disposed in the trench, the filling material surrounded by the second dielectric layer;
the first dielectric layer being disposed between the metal grid and the dielectric filling material of each of the plurality of isolation structures;
a backside contact structure extending through the semiconductor substrate, the backside contact structure disposed within a peripheral region that surrounds an active pixel region including the array;
the metal grid including a portion extending from the active pixel region into the peripheral region proximate to the backside contact structure and a third dielectric layer is disposed between the portion of the metal grid extending from the active pixel region into the peripheral region and the backside contact structure, the third dielectric layer being formed of a material different from the first dielectric.