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Samsung patents image sensor design with dual trench isolation

Samsung has been granted a patent for a specific layout in CMOS image sensors that separates the light-sensing part from the processing transistors. The design uses two shallow trenches on the front of the chip and a deeper trench on the back to create a continuous barrier between these areas.

Why it mattersThis is a detailed hardware improvement that helps manage electrical interference in camera sensors, which is standard engineering work for maintaining image quality in phones and cameras.

In the filing’s own words

A pixel cell for a CMOS image sensor includes an isolation structure that isolates a pixel transistor region from a pixel photodiode region. On a front side of the image sensor, the isolation structure includes a first shallow trench isolation (STI) structure, a second STI structure and a semiconductor region between the first STI structure and the second STI structure, and an implant region formed from a p-type semiconductor that is in contact with the semiconductor region and extends toward a backside of the image sensor. The semiconductor region is formed from the first type semiconductor. On a backside of the image sensor, the isolation structure includes a trench isolation structure extending from the backside toward the front side and that contacts the implant region.

What exactly they claim (claim 1)

1. A pixel cell for a CMOS image sensor, comprising: a semiconductor substrate having a first side and a second side that is opposite the first side; a first pixel region that includes at least one first photodiode, the first photodiode comprising a first region formed from a first type semiconductor on the first side of the semiconductor substrate and a second region formed from a second type semiconductor on the first side of the semiconductor substrate; a pixel transistor region including at least one transistor; and an isolation structure that isolates the pixel transistor region from the first photodiode, the isolation structure on the first side of the semiconductor substrate comprising a first shallow trench isolation (STI) structure that is proximate to the second region of the first photodiode, a third region formed from the first type semiconductor that is proximate to the first STI structure, a second STI structure that is proximate to the third region and that is proximate to the pixel transistor region, and an implant region formed from the first type semiconductor that is in contact with the third region and extends toward the second side of the semiconductor substrate; and a backside trench isolation (BTI) structure extending from the second side of the semiconductor substrate toward the implant region and in contact with the implant region, wherein the first STI structure, the third region, the second STI structure, the implant region, and the BTI structure cooperatively form a continuous lateral isolation boundary between the pixel transistor region and the first photodiode.

Facts

Company
Samsung (Samsung Electronics Co., Ltd.)
Official title
CMOS image sensor wherein the isolation structure has two STI and backside trench isolation
Patent number
US12733270B2
Application number
18096012
Filed
Jan 11, 2023
Granted
Sep 8, 2026
Inventors
2
Claims
20

Classified under

H10F 39/18 Electricity & electronicsH10F 39/8037 Electricity & electronicsH10F 39/807 Electricity & electronicsH10F 39/811 Electricity & electronics
Read the full filing (official PDF) ↗ Open in the Patent Tracker

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Summaries are simplified from the filing’s own abstract and first claim. A patent filing is not a product announcement.
Patent data and drawings: U.S. Patent and Trademark Office (USPTO). Nebula is not affiliated with or endorsed by the USPTO.