Full-Depth Pixel Sensor Isolation for Optical Crosstalk
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Solution Overview
Problem
Optical crosstalk between adjacent pixel regions in a pixel array degrades spatial resolution, reduces sensitivity, causes color mixing, and leads to image noise in CMOS image sensors.
Innovation Solution
Implementing full deep trench isolation (DTI) structures that extend the full height of the substrate to absorb or reflect incident light, and using extended conductive structures with absorption layers to enhance visible light reflection and infrared light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full deep trench isolation structures are implemented to reduce optical crosstalk, then spatial resolution and sensitivity improve, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The substrate is divided into discrete pixel regions separated by deep trench isolation structures. Each pixel region is independently isolated by trenches filled with dielectric material, preventing optical crosstalk between adjacent pixels while maintaining individual photodetector functionality.
Solution Approach 2:
The deep trench isolation structures are strategically positioned only at boundaries between pixel regions where optical crosstalk occurs, rather than uniformly across the entire substrate. This localized approach reduces overall device complexity while effectively addressing the crosstalk problem at critical interfaces.
2Loss of information
If deep trench isolation structures extend full substrate height to block optical crosstalk, then color mixing reduces, but manufacturing precision requirements increase
Solution Approach 1:
The deep trench isolation structures utilize composite material composition, combining dielectric fill material within the trenches with the substrate material. This composite approach provides effective optical isolation through the full substrate height while the dielectric material's optical properties enhance crosstalk reduction without requiring perfectly uniform trench dimensions.
3Use of energy by moving object
If extended conductive structures with absorption layers are added to enhance light reflection and absorption, then low-light performance improves, but device complexity increases
Solution Approach 1:
The extended conductive structures serve multiple functions simultaneously: they provide electrical connectivity for charge collection, act as light reflection surfaces to redirect photons toward photodetectors, and when combined with absorption layers, function as infrared filtering elements. This multi-functionality reduces the need for separate dedicated structures for each function.
Solution Approach 2:
The conductive structures are combined with absorption layers forming a composite structure that leverages the electrical conductivity of the metal for charge collection while the absorption layer material provides selective infrared light absorption. This composite approach enhances low-light and night vision performance without requiring entirely separate systems.
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
This approach increases spatial resolution, sensitivity, reduces color mixing, and decreases image noise, while improving low-light performance and enabling full-color night vision capabilities.
Implementation Method 1
full deep trench isolation (DTI) structures that extend the full height of the substrate to absorb or reflect incident light
Implementation Method 2
full deep trench isolation (DTI) structures that extend the full height of the substrate to absorb or reflect incident light
Implementation Method 3
using extended conductive structures with absorption layers to enhance visible light reflection and infrared light absorption
Data Source
AI summary
A pixel sensor may include a deep trench isolation (DTI) structure that extends the full height of a substrate in which a photodiode of the pixel sensor is included. Incident light entering the pixel sensor at a non-orthogonal angle is absorbed or reflected by the DTI structure along the full height of the substrate. In this way, the DTI structure may reduce, minimize, and/or prevent the incident light from traveling through the pixel sensor and into an adjacent pixel sensor along the full height of the substrate. This may increase the spatial resolution of an image sensor in which the DTI structure is included, may increase the overall sensitivity of the image sensor, may reduce and/or prevent color mixing between pixel sensors of the image sensor, and/or may decrease image noise after color correction.