Patent ID: 11862509
Assignee: OMNIVISION TECHNOLOGIES, INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 6:
7. A CMOS image sensor formed in a semiconductor substrate having a front-side surface comprising:
a first photodiode region comprising at least a first photodiode;
a second photodiode region comprising at least a second photodiode;
a pixel transistor region between the first photodiode region and the second photodiode region and comprising at least one transistor having a gate on the front-side surface and a source/drain in the semiconductor substrate adjacent to the gate;
a first shallow trench isolation (STI) structure comprising a first trench filled with a dielectric material, the first trench having a first depth D relative to the front-side surface to provide isolation between the first photodiode region and the pixel transistor region, said first trench having a hexagonal shaped cross-section in the semiconductor substrate between the first photodiode region and the pixel transistor region, wherein a width of the first trench varies along a depth of the first trench in the semiconductor substrate from a first width W at the front-side surface to a second width W1 larger than the first width W at a second depth D1 relative to the front-side surface then to a third width W2 smaller than the first width W at the first depth D, wherein the first depth D is greater than the second depth D1 with respect to the front-side surface; and
a second STI structure disposed between the second photodiode region and the pixel transistor region and spaced from the first STI structure, the second STI structure comprising a second trench having the first depth D filled with a dielectric and having the hexagonal shaped cross-section.