Patent ID: 11862654
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method for forming an image sensor, the method comprising:
forming a pixel comprising a photodetector in a substrate;
patterning the substrate to form an inner trench, wherein the inner trench has a pair of inner trench segments between which the photodetector is sandwiched;
forming a dielectric layer filling the inner trench;
patterning the substrate and the dielectric layer to form an outer trench, wherein the outer trench surrounds the photodetector along a boundary of the pixel and has a pair of outer trench segments respectively on opposite sides of the photodetector and between which the inner trench segments are sandwiched;
depositing a low-transmission layer covering the substrate and filling the outer trench, wherein the low-transmission layer blocks incident radiation regardless of incident angle; and
performing a planarization into the low-transmission layer, wherein a top surface of the low-transmission layer is level with a top surface of the dielectric layer and is elevated relative to a top surface of the substrate upon completion of the planarization.