Imaging Sensors with In-Layer Lenses to Reduce Wiring Reflection
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Solution Overview
Problem
Conventional imaging elements suffer from light reflection at the wiring layer, leading to image quality degradation due to fluctuating sensitivity caused by incident angle changes and color mixture.
Innovation Solution
Incorporation of on-chip lenses and a plurality of in-layer lenses between the on-chip lens and photoelectric conversion unit, with the in-layer lenses arranged in the same layer and configured to collect incident light individually on the photoelectric conversion unit, optionally with color filters to allow specific wavelengths and asymmetric arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rear surface irradiation type imaging element is used to improve sensitivity, then sensitivity is improved, but light reflection from the wiring layer causes color mixture and image quality degradation
Solution Approach 1:
The patent divides the single lens function into multiple in-layer lenses (first, second, and third in-layer lenses) with different focal lengths and positions. This segmentation allows each lens to collect light at different angles and focus it onto the photoelectric conversion unit, thereby reducing the impact of reflected light from the wiring layer while maintaining high sensitivity.
Solution Approach 2:
The in-layer lenses act as intermediary optical elements between the on-chip lens and the photoelectric conversion unit. These lenses redirect and redistribute the light paths, including reflected light from the wiring layer, to prevent color mixture and improve image quality while preserving the sensitivity benefits of rear surface irradiation.
2Reliability
If symmetric wiring configuration is used to make reflected light amount constant, then sensitivity fluctuation is reduced, but image quality degradation from reflection cannot be eliminated
Solution Approach 1:
The patent employs multiple in-layer lenses with different optical characteristics to segment the light collection function. This allows the system to handle reflected light from symmetric wiring configurations by distributing it across multiple focal points, thereby eliminating image quality degradation while maintaining sensitivity stability.
Solution Approach 2:
The patent changes the optical parameters (focal lengths, positions, and arrangements) of the in-layer lenses to optimize the handling of reflected light. By adjusting these parameters, the system can maintain constant sensitivity while preventing image quality degradation from wiring layer reflection.
3Object-affected harmful factors
If multiple in-layer lenses are added to reduce reflection and improve image quality, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent implements a nested lens structure where the first, second, and third in-layer lenses are arranged in overlapping or concentric configurations within the same pixel region. This nesting approach allows multiple lens functions to be integrated in a compact space, reducing device complexity while maintaining the ability to reduce wiring layer reflection.
Solution Approach 2:
The patent merges the functions of multiple in-layer lenses with the on-chip lens and the photoelectric conversion unit into a single integrated pixel structure. This combining approach reduces overall device complexity by eliminating the need for separate components while achieving the goal of reducing light reflection and improving image quality.
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
Reduces light reflection from the wiring layer, enhancing image quality by scattering incident light uniformly and allowing flexible wiring layer configurations.
Implementation Method 1
an on-chip lens configured to collect incident light from a subject
Implementation Method 2
a plurality of in-layer lenses that is arranged between the on-chip lens and the photoelectric conversion unit and that is configured to further collect the incident light that has passed through the on-chip lens
Implementation Method 3
a photoelectric conversion unit configured to perform photoelectric conversion on the collected incident light
Implementation Method 4
a color filter configured to allow light having a predetermined wavelength, out of the incident light that has passed through the on-chip lens, to transmit through the color filter
Data Source
AI summary
The deterioration of the image quality of an imaging element is to be prevented.The imaging element includes an on-chip lens, a photoelectric conversion unit, and a plurality of in-layer lenses. The on-chip lens collects incident light from a subject. The photoelectric conversion unit performs photoelectric conversion on the collected incident light. The plurality of in-layer lenses that is arranged between the on-chip lens and the photoelectric conversion unit and that is configured to further collect the incident light that has passed through the on-chip lens. Furthermore, the plurality of in-layer lenses allows the incident light that has passed through any one of the plurality of in-layer lenses to be incident on the photoelectric conversion unit.