Pixel Array Light-Shielding Layout for Crosstalk Suppression
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Solution Overview
Problem
In imaging devices with high-sensitivity and low-sensitivity pixels, crosstalk between pixels occurs due to the significant difference in sensitivity, leading to degradation of image quality.
Innovation Solution
The implementation of a pixel array with a trench light-shielding portion around each pixel, where the trench light-shielding portion is provided without gaps around the high-sensitivity pixels and spaced apart from the low-sensitivity pixels, and a light-shielding wall is embedded in the trench at the boundary between pixels to prevent light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If large-area and small-area photoelectric conversion elements are arranged in a unit pixel to achieve high sensitivity and low saturation, then sensitivity range is improved, but crosstalk between pixels occurs due to significant sensitivity difference
Solution Approach 1:
The patent divides the light-shielding structure into two distinct types: trench light-shielding portions for high-sensitivity pixels and spaced light-shielding portions for low-sensitivity pixels. This segmentation allows each pixel type to have optimized light isolation, preventing crosstalk while maintaining the mixed sensitivity configuration within unit pixels.
Solution Approach 2:
The patent applies different light-shielding configurations to different pixel types based on their sensitivity characteristics. High-sensitivity pixels receive complete trench light-shielding, while low-sensitivity pixels have spaced light-shielding portions, creating local quality differences that address the specific needs of each pixel type and reduce crosstalk.
2Object-affected harmful factors
If trench light-shielding portion is provided without gap around high-sensitivity pixel, then crosstalk is reduced, but manufacturing complexity increases
Solution Approach 1:
The light-shielding structure is segmented into trench portions for high-sensitivity pixels and non-trench portions for low-sensitivity pixels. This segmentation reduces the overall complexity by applying the complex trench structure only where necessary (around high-sensitivity pixels) rather than uniformly across all pixels.
Solution Approach 2:
The trench light-shielding structure is applied locally only to high-sensitivity pixels that require maximum light isolation, while low-sensitivity pixels use simpler spaced light-shielding portions. This local application of complex structure minimizes overall device complexity while still achieving crosstalk reduction where most needed.
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 configuration effectively suppresses crosstalk between high-sensitivity and low-sensitivity pixels, improving image quality by maintaining sensitivity differences while reducing light interference.
Implementation Method 1
a first pixel having a first photoelectric conversion element and a second pixel having a second photoelectric conversion element
Implementation Method 2
an accumulation portion that accumulates a charge generated by the second photoelectric conversion element and converts the accumulated charge into a voltage
Implementation Method 3
a light-shielding portion provided between each of the plurality of pixels included in the pixel array
Data Source
AI summary
An imaging element according to an embodiment includes: a unit pixel including a first pixel having a first photoelectric conversion element and including a second pixel having a second photoelectric conversion element, the second pixel being arranged adjacent to the first pixel; and an accumulation portion that accumulates a charge generated by the second photoelectric conversion element and converts the accumulated charge into a voltage. The accumulation portion is disposed at a boundary between the unit pixel and another unit pixel adjacent to the unit pixel.