Solid-State Image Sensor Pixel Shielding for Color Mixing Control
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Solution Overview
Problem
The existing solid-state imaging devices face challenges in suppressing color mixing between different colors while reducing sensitivity differences between same colors, due to scattered light infiltrating into surrounding photoelectric conversion units.
Innovation Solution
A solid-state imaging device is designed with a microlens array, a scatterer on the optical path, and an inter-pixel light shielding portion featuring a groove with an inclined or curved opening side, filled with an insulating material, to guide and scatter light effectively while minimizing color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a scatterer is provided at a light collecting point of a microlens to distribute collected light to four adjacent photoelectric conversion units, then sensitivity difference between same colors is suppressed, but scattered light infiltrates into surrounding photoelectric conversion units causing color mixing between different colors
Solution Approach 1:
The invention divides the light distribution function into two separate components: the scatterer handles sensitivity uniformity by distributing light among adjacent photoelectric conversion units of the same color, while the inter-pixel light shielding portions handle color mixing prevention by blocking scattered light from reaching surrounding photoelectric conversion units of different colors. This segmentation resolves the contradiction by assigning different functions to different structural elements.
Solution Approach 2:
The inter-pixel light shielding portions act as intermediary elements positioned between the scatterer and the surrounding photoelectric conversion units. These shielding portions mediate the light path by allowing desired light distribution to photoelectric conversion units of the same color while blocking unwanted light from reaching photoelectric conversion units of different colors, thus resolving the color mixing issue while maintaining sensitivity uniformity.
2Manufacturing precision
If light is distributed by the scatterer to reduce sensitivity difference, then sensitivity difference between same colors is reduced, but the quality of the obtained image degrades due to color mixing
Solution Approach 1:
The invention segments the optical system into distinct functional zones: the scatterer zone for sensitivity uniformity and the inter-pixel light shielding portions for color isolation. This segmentation allows the system to achieve both sensitivity uniformity and high image quality by preventing color mixing while maintaining light distribution to same-color photoelectric conversion units.
Solution Approach 2:
The invention converts the potentially harmful scattered light that causes color mixing into a beneficial element by using the inter-pixel light shielding portions to redirect it. The scattered light is still distributed to photoelectric conversion units of the same color (beneficial for sensitivity uniformity), but the shielding portions prevent it from reaching photoelectric conversion units of different colors (converting the potential harm into a controlled benefit).
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 solution effectively suppresses color mixing and reduces sensitivity differences between same colors, thereby enhancing the quality of images obtained by the solid-state imaging device.
Implementation Method 1
a microlens array including a microlens formed for a photoelectric conversion unit group including at least two or more adjacent photoelectric conversion units to guide incident light to the photoelectric conversion unit group
Implementation Method 2
a scatterer disposed on an optical path of the incident light collected by the microlens... so that the collected light is scattered by the scatterer and distributed to four adjacent photoelectric conversion units
Implementation Method 3
a plurality of photoelectric conversion units formed on a substrate to generate signal charges according to an amount of incident light
Data Source
AI summary
Provided is a solid-state imaging device that includes a plurality of photoelectric conversion units formed on a substrate to generate signal charges according to an amount of incident light, a microlens array including a microlens for a photoelectric conversion unit group including at least two or more adjacent photoelectric conversion units to guide incident light to the photoelectric conversion unit group, a scatterer on an optical path of the incident light collected by the microlens, and an inter-pixel light shielding portion including a groove between the photoelectric conversion unit of the photoelectric conversion unit group and the photoelectric conversion unit adjacent to the photoelectric conversion unit group and an insulating material filled in the groove. An opening side of an inner side surface of the groove on the scatterer side is a flat surface inclined so that a groove width becomes narrower toward a bottom of the groove.