Reflective Deep Trench Isolation for CMOS Pixel Cross-Talk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As pixel regions in CMOS image sensors become smaller, cross-talk 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 the image sensor integrated chip, which reflects electromagnetic radiation and reduces cross-talk between pixel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel regions are made smaller to increase resolution, then the number of pixels increases, but cross-talk between adjacent pixel regions increases due to intervening layers with different indices of refraction
Solution Approach 1:
A reflective element is introduced as an intermediary component between adjacent pixel regions. This reflective element serves as a mediator that redirects stray light away from neighboring pixels, preventing cross-talk while allowing the pixel regions to remain small for high resolution imaging.
Solution Approach 2:
The intervening layers with different indices of refraction that cause cross-talk are converted into a beneficial structure. By strategically placing reflective elements at interfaces between layers with different refractive indices, the patent transforms the harmful refraction and reflection of stray light into a controlled mechanism that directs light away from adjacent pixels, thereby reducing cross-talk.
2Object-affected harmful factors
If deep trench isolation structures are added to reduce cross-talk, then cross-talk reduction is achieved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The reflective element is merged with the existing deep trench isolation structure. Rather than adding a completely separate component, the reflective element is integrated into the trench isolation, allowing it to perform dual functions: electrical isolation between pixels and optical reflection to reduce cross-talk, thereby reducing overall device complexity.
Solution Approach 2:
The deep trench isolation structure is given multiple functions. It not only provides electrical isolation between adjacent pixel regions but also incorporates a reflective element that reduces optical cross-talk. This multi-functionality reduces the need for additional separate structures, simplifying the overall device design.
3Object-affected harmful factors
If deep trench isolation structures with reflective elements are implemented, then cross-talk is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The reflective element is formed within the trench structure during the same manufacturing process steps used to create the deep trench isolation. By performing the reflection layer deposition and patterning as preliminary actions within the existing process flow, rather than adding separate precision-critical steps, the manufacturing precision requirements are minimized while still achieving effective cross-talk reduction.
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 with a reflective element effectively reduces cross-talk and improves the quantum efficiency of the image sensor integrated chip, leading to enhanced image quality.
Implementation Method 1
a reflective element configured to reflect electromagnetic radiation
Implementation Method 2
an image sensing element arranged within a substrate
Data Source
AI summary
The present disclosure, in some embodiments, relates to an integrated chip. The integrated chip includes a substrate having an image sensor region arranged between sidewalls of the substrate that form one or more trenches. One or more dielectric materials are arranged along the sidewalls of the substrate that form the one or more trenches. A reflective region is disposed within the one or more trenches and laterally surrounded by the one or more dielectric materials. The reflective region includes a plurality of reflective portions that are arranged at different vertical positions within the reflective region and that have different reflective properties.