Patent ID: 11862678
Assignee: OMNIVISION TECHNOLOGIES, INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A pixel-array substrate, comprising:
a semiconductor substrate including a pixel array including a plurality of pixels, a back surface and a front surface opposite the back surface;
a first guard ring being formed of a p-doped semiconductor, enclosing the pixel array, and extending into the semiconductor substrate from the front surface;
a second guard ring formed of a p-doped semiconductor, enclosing the first guard ring, and extending into the semiconductor substrate from the front surface; and
a third guard ring that encloses the first guard ring and is enclosed by the second guard ring, the third guard ring extending into the semiconductor substrate from the front surface and being formed of an n-doped semiconductor material,
the back surface forming (i) a first trench that extends into the semiconductor substrate, overlaps the first guard ring along a horizontal plane, and (ii) a second trench formed by the back surface and overlapping, along the horizontal plane, the second guard ring,
each of the first trench and the second trench being one or both of: (a) coated with a high-κ passivation layer and (b) filled with an oxide material;
the semiconductor substrate including (i) a first substrate region that surrounds the pixel array and spatially isolates each of the first guard ring and the first trench from the pixel array and regions between adjacent pixels of the plurality of pixels, (ii) a second substrate region that surrounds the first guard ring, and (iii) a third substrate region that surrounds the second guard ring.