Patent ID: 11869761
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 10:
11. A method of forming an image sensor, comprising:
forming photodiodes for a plurality of pixel regions from a front-side of an image sensing die, wherein a photodiode is formed to have a photodiode doping column with a first doping type surrounded by a photodiode doping layer with a second doping type that is different than the first doping type;
forming a doped isolation well from the front-side of the image sensing die by implanting dopants into the photodiode doping layer through at least one implanting process;
forming a gate structure and a metallization stack on the front-side of the image sensing die, wherein the metallization stack comprises a plurality of metal interconnect layers arranged within one or more inter-level dielectric layers;
bonding the image sensing die to a logic die from the front-side of the image sensing die, wherein the logic die comprises logic devices;
forming a deep trench between adjacent pixel regions in a back-side of the image sensing die;
performing a cyclic cleaning process to remove an upper portion of the photodiode doping layer exposed to the deep trench;
forming a doped liner with the second doping type lining a sidewall surface of the deep trench; and
forming a dielectric fill layer filling an inner space of the deep trench to form a back-side deep trench isolation (BDTI) structure;
wherein the cyclic cleaning process reduces a bowing angle of a bowing tip at a top corner of the deep trench to be smaller than 15° from an upper sidewall to a vertical line perpendicular to a lateral plane of the photodiode doping layer.