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

Claim 14:
15. A method for forming an image sensor, the method comprising:
forming a pixel comprising a photodetector in a substrate;
patterning the substrate to form a first trench surrounding the photodetector with a pair of first-trench segments between which the photodetector is sandwiched;
depositing a dielectric layer filling the first trench and covering the pixel;
patterning the substrate to form a second trench surrounding the photodetector with a pair of second-trench segments between which the first-trench segments are sandwiched, wherein the patterning to form the second trench is performed into both the dielectric layer and the substrate;
depositing a liner layer lining the second trench; and
depositing a metal layer filling the second trench over the liner layer and covering the dielectric layer;
wherein the first and second trenches extend through the substrate, from top to bottom, wherein the metal layer is more absorptive of incident radiation than the dielectric layer, and wherein a top surface of the liner 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 depositing of the liner layer.