CMOS Image Sensor Deep Trench Isolation for Pixel Crosstalk
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Solution Overview
Problem
As CMOS image sensors reduce pixel region size to increase resolution, crosstalk between adjacent pixel regions increases due to intervening layers with different indices of refraction, degrading image quality.
Innovation Solution
The implementation of a deep trench isolation (DTI) structure with a reflective element in CMOS image sensors, which includes protrusions and absorption enhancement layers to reduce crosstalk by reflecting electromagnetic radiation back to the intended pixel region, thereby improving quantum efficiency and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel region size is reduced to increase resolution, then image resolution is improved, but crosstalk between adjacent pixel regions increases
Solution Approach 1:
The patent introduces deep trench isolation structures that physically segment and separate adjacent pixel regions. These trenches extend deep into the substrate, creating isolated compartments for each pixel region, which prevents optical crosstalk while maintaining high resolution by allowing continued miniaturization of pixel elements within each isolated region.
Solution Approach 2:
The patent employs reflective elements positioned within or adjacent to the deep trench isolation structures as intermediary components. These reflective elements intercept and redirect stray light that would otherwise cause crosstalk, reflecting it back toward the intended pixel region or away from adjacent pixels, thereby eliminating the harmful optical interference.
2Object-generated harmful factors
If deep trench isolation structure with reflective element is implemented, then crosstalk is reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the deep trench isolation structure: it serves simultaneously as an electrical isolation element, an optical isolation barrier, and a support structure for reflective elements. This integration reduces overall device complexity by eliminating the need for separate structures for each function, while still achieving effective crosstalk reduction.
Solution Approach 2:
The deep trench isolation structure is designed as a multi-functional element that performs electrical isolation, optical isolation, and structural support roles. The reflective elements within the trenches provide both optical reflection and additional electrical isolation, maximizing the utility of each added component and reducing the need for additional separate structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The DTI structure effectively reduces crosstalk and enhances quantum efficiency, leading to improved performance and image quality by minimizing light interference between pixel regions.
Implementation Method 1
a reflective element configured to reflect electromagnetic radiation
Implementation Method 2
one or more absorption enhancement layers arranged over and between the plurality of protrusions
Data Source
AI summary
The present disclosure, in some embodiments, relates to an image sensor integrated chip. The image sensor integrated chip includes a substrate having a pixel region arranged between one or more trenches formed by sidewalls of the substrate. One or more dielectric materials are arranged along the sidewalls of the substrate forming the one or more trenches. A conductive material is disposed within the one or more trenches. The conductive material is electrically coupled to an interconnect disposed within a dielectric arranged on the substrate.