Back-Illuminated CMOS Pixel Shield Layout Against Color Mixing
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Solution Overview
Problem
Existing solid-state imaging devices face challenges in preventing color mixing due to light diffracted or reflected below the inter-pixel light shielding portions, which hinders the achievement of higher-resolution image taking.
Innovation Solution
The imaging element incorporates a photoelectric conversion portion in a semiconductor substrate with an element isolation portion and an inter-pixel light shielding portion disposed between the substrate and the filter layer, where the interval between the light receiving surface and the tip end surface of the inter-pixel light shielding portion is smaller than its width, effectively preventing light from leaking into adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an inter-pixel light shielding portion is provided between pixels, then color mixing between adjacent pixels is reduced, but light diffracted or reflected below the shielding portion still causes color mixing
Solution Approach 1:
The patent introduces a new spatial dimension by positioning the inter-pixel light shielding portion at a height above the semiconductor substrate surface, rather than only at the substrate level. This vertical displacement creates a three-dimensional light blocking structure that intercepts light paths at multiple heights, effectively preventing diffracted and reflected light from causing color mixing between adjacent pixels.
Solution Approach 2:
The patent introduces an absorbing layer as an intermediary substance between the inter-pixel light shielding portion and the semiconductor substrate. This absorbing layer acts as a mediator that captures and absorbs light that passes through or around the shielding portion, preventing it from reaching adjacent pixels and causing color mixing.
2Object-affected harmful factors
If the interval between the light receiving surface and the tip end surface of the inter-pixel light shielding portion is reduced, then light leakage is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the interval parameter between the light receiving surface and the tip end surface of the inter-pixel light shielding portion to a specific range (0.1-1.0 μm). By carefully controlling this parameter, the patent achieves effective light leakage prevention while maintaining manufacturability. The absorbing layer further compensates for slight variations in this interval, reducing the stringency of precision requirements.
3Object-affected harmful factors
If the width of the tip end surface of the inter-pixel light shielding portion is increased, then color mixing prevention is enhanced, but device complexity increases
Solution Approach 1:
The patent applies local quality by making the tip end surface width of the inter-pixel light shielding portion larger than other portions. This localized widening is specifically applied at the critical interface where light leakage and diffraction occur most frequently, providing enhanced color mixing prevention exactly where needed without unnecessarily increasing the overall device complexity.
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 enhances the prevention of color mixing, allowing for higher-resolution image capture by attenuating light through increased reflections and absorption within the element isolation portion, thereby reducing the probability of color mixing.
Implementation Method 1
an interval between the light receiving surface of the semiconductor substrate and a tip end surface of the inter-pixel light shielding portion is smaller than a width of the tip end surface of the inter-pixel light shielding portion
Implementation Method 2
attenuating light through increased reflections and absorption within the element isolation portion
Implementation Method 3
a photoelectric conversion portion that is provided in a semiconductor substrate for each of pixels and performs photoelectric conversion on light that enters through a filter layer
Data Source
AI summary
The present disclosure relates to an imaging element and an electronic apparatus configured to achieve higher-resolution image taking. The imaging element includes: a photoelectric conversion portion provided in a semiconductor substrate for each pixel that performs photoelectric conversion on light that enters through a filter layer; an element isolation portion configured to separate the photoelectric conversion portions of adjacent pixels; and an inter-pixel light shielding portion disposed between the pixels in a layer and provided between the semiconductor substrate and the filter layer and separated from a light receiving surface of the semiconductor substrate by a predetermined interval. Moreover, an interval between the light receiving surface of the semiconductor substrate and a tip end surface of the inter-pixel light shielding portion is smaller than a width of the tip end surface of the inter-pixel light shielding portion. The present technology is applicable to back-illuminated CMOS image sensors, for example.