Multi-depth trench insulation (MDTI) structure for CMOS image sensor

The MDTI and BDTI structures in CMOS image sensors enhance NIR sensitivity and reduce crosstalk, addressing the challenges of improving detection quality in NIR applications.

DE102018126875B4Active Publication Date: 2026-06-03TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD
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Patent Information

Application Number
DE102018126875
Authority / Receiving Office
DE · DE
Patent Type
Patents
Current Assignee / Owner
Priority Date
2017-11-27
Filing Date
2018-10-28
Publication Date
2026-06-03
Estimated Expiration
2038-10-28

AI Technical Summary

Technical Problem

Existing CMOS image sensors face challenges in enhancing near-infrared (NIR) sensitivity while minimizing lateral crosstalk and maintaining detection quality, especially at small pixel sizes, which is crucial for applications like security and area search.

Method used

Implementing a multi-deep trench insulation (MDTI) structure within each pixel region and a boundary deep trench insulation (BDTI) structure between adjacent pixel regions, using dielectric layers with a lower dielectric constant than the substrate, to redirect incoming radiation and reduce lateral photon crosstalk.

Benefits of technology

Improves NIR sensitivity and reduces stray light and crosstalk, enhancing the detection quality of CMOS image sensors.

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Abstract

CMOS image sensor, which includes the following: a substrate (102) with a front (122) and a back (124) opposite the front (122); a plurality of pixel regions (103a, 103b, 103c, 103d) arranged on the substrate (102), each comprising a photodiode (104) designed to convert radiation entering the substrate (102) from the rear (124) into an electrical signal; a BDTI structure (111) arranged between adjacent pixel regions (103a, 103b, 103c, 103d), which extends from the back (124) of the substrate (102) into a first depth (d1) in the substrate (102) and surrounds the photodiode (104); an MDTI structure (110) arranged in the multitude of pixel regions (103a, 103b, 103c, 103d), which extends from the back (124) of the substrate (102) into a second depth (d2) in the substrate (102) and superimposes the photodiode (104); and a dielectric layer (115) that fills a BDTI trench (802) of the BDTI structure (111) and an MDTI trench (702) of the MDTI structure (110); wherein the MDTI structure (110) comprises segments that are spaced apart from each other and symmetrical along a midline of the pixel region (103a, 103b, 103c, 103d).
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Citation Information

Patent Citations

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  • Image sensors using different photoconversion region isolation structures for different types of pixel regions

    US9911777B2