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

Claim 7:
8. A method for forming an image sensor, the method comprising:
forming a pixel comprising a photodetector in a substrate;
performing a first etch into the substrate to form a recess with a saw-toothed profile overlying the photodetector;
performing a second etch into the substrate to form a first trench, wherein the first trench extends in a first closed path to surround the pixel;
depositing a dielectric layer filling the recess and the first trench;
performing a third etch into the substrate and the dielectric layer to form a second trench, wherein the second trench extends along a boundary of the pixel in a second closed path to surround the first trench;
depositing a metal layer covering the substrate and filling the second trench, wherein the metal layer blocks incident radiation; and
recessing the metal layer to remove portions of the metal layer outside the second trench, wherein the recessing comprises a planarization into the metal layer, and wherein a top surface of the metal 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;
wherein a height of the first trench is substantially equal to a height of the substrate.