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

Claim 0:
1. A shallow trench isolation (STI) structure formed in a semiconductor substrate having a front-side surface, the STI structure having a first width Win the same plane as the front-side surface and a first depth D perpendicular to the front-side surface, to provide isolation between a photodiode region comprising a photodiode and a pixel transistor region comprising at least one transistor, the STI structure comprising:
a trench disposed on the front-side surface such that the trench extends into the semiconductor substrate to the first depth D relative to the front-side surface, said trench having a hexagonal shaped cross-section in the semiconductor substrate between the photodiode region and the pixel transistor region, wherein a width of the trench varies along the depth of the trench from a first width W at the front-side surface to a second width W1 larger than 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 dielectric material filing the trench.