Pixel Isolator Layout for Imaging Sensors With Lower Crosstalk
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Solution Overview
Problem
In solid-state imaging elements, the formation of trenches for inter-pixel isolators can lead to increased process load and wafer warpage due to intersecting portions, which may result in signal degradation and crosstalk between pixels.
Innovation Solution
A solid-state imaging element with a pixel array unit where inter-pixel isolators are formed without intersecting each other, and filters with the same light transmission characteristics are disposed between adjacent pixels to manage crosstalk and reduce process load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If trenches are formed to create inter-pixel isolators, then crosstalk between pixels is reduced, but process load increases and wafer warpage occurs due to intersecting portions
Solution Approach 1:
The patent applies partial action by forming inter-pixel isolators only at specific locations where crosstalk is most problematic, rather than creating a complete grid of isolators across all pixel boundaries. This selective approach reduces the number of trenches needed, minimizing intersecting portions and associated manufacturing issues while still achieving effective crosstalk suppression in critical areas
Solution Approach 2:
The patent implements local quality by varying the density and placement of inter-pixel isolators based on local crosstalk requirements. Different regions of the pixel array receive different isolator configurations tailored to their specific optical and electrical characteristics, reducing overall process complexity while maintaining effective isolation where needed
2Object-affected harmful factors
If trenches are formed to create inter-pixel isolators, then crosstalk between pixels is reduced, but wafer warpage occurs due to intersecting portions
Solution Approach 1:
By forming trenches only at necessary locations rather than creating a complete isolator grid, the patent minimizes the number of intersecting portions that cause cumulative stress and wafer warpage, while still achieving adequate pixel isolation
Solution Approach 2:
The patent optimizes trench parameters such as depth, width, and spacing to reduce stress accumulation. By carefully controlling these geometric parameters and the distribution of intersecting portions, the patent minimizes wafer warpage while maintaining effective crosstalk suppression
3Reliability
If filters with the same light transmission characteristic are disposed between adjacent pixels, then charge movement is controlled, but manufacturing complexity increases
Solution Approach 1:
The patent merges the functions of adjacent pixels by disposing filters with the same light transmission characteristic between them, allowing these pixels to effectively function as an extended single pixel. This reduces the need for complex isolation structures and simplifies the filter arrangement while maintaining signal integrity through controlled charge movement
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 reduces the deterioration of the extinction ratio and pixel signal degradation by ensuring charges move based on the same polarization direction or wavelength band, even in areas without inter-pixel isolators, thereby minimizing signal loss and manufacturing complexities.
Implementation Method 1
a polarizing filter having a different polarization direction (polarization axis) is disposed for every pixel
Implementation Method 2
a photoelectric converter is arranged in each of a row direction and a column direction
Data Source
AI summary
A solid-state imaging element includes a pixel array unit in which a plurality of pixels each having a photoelectric converter is arranged in each of a row direction and a column direction, in which the pixel array unit includes an inter-pixel isolator that isolates the plurality of pixels adjacent to each other, each of the plurality of pixels includes a filter having a predetermined light transmission characteristic, the inter-pixel isolator is formed without intersecting the inter-pixel isolator, and the filter having a same light transmission characteristic is disposed between the plurality of pixels adjacent to each other.