Color Filter Partition Wall Layout for High-Angle Light Suppression
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Solution Overview
Problem
In imaging devices, obliquely incident light can be reflected by partition walls, leading to color mixing and deterioration in imaging performance due to high-angle incident light being photoelectrically converted in pixels.
Innovation Solution
The imaging device incorporates a semiconductor substrate with photoelectric conversion elements, color filters, and a partition wall structure comprising a first metal layer, a translucent first partition wall layer, and a second translucent partition wall layer with a higher refractive index, which attenuates high-angle incident light by repeatedly reflecting it between the metal layer and partition wall layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a partition wall is provided between adjacent color filters to prevent color mixing, then color mixing between pixels is reduced, but high-angle incident light is reflected by the partition wall and causes color mixing in pixel signals
Solution Approach 1:
The patent converts the harmful reflection of high-angle light by the partition wall into a beneficial effect by introducing a light-absorbing layer that selectively absorbs the reflected light. The partition wall's reflection, which originally caused color mixing, is now utilized to direct light toward the light-absorbing layer, which then prevents it from reaching adjacent pixels. This transforms the harmful reflective property into a useful mechanism for light management.
Solution Approach 2:
The light-absorbing layer acts as an intermediary element between the partition wall and the photoelectric conversion elements. It mediates the interaction by absorbing the light reflected from the partition wall before this light can reach adjacent pixels and cause color mixing. This intermediary layer effectively decouples the partition wall's reflective function from its harmful effect on image quality.
2Object-affected harmful factors
If the partition wall is made opaque to block light effectively, then light blocking between pixels is improved, but imaging performance deteriorates due to loss of useful light
Solution Approach 1:
The partition wall is designed with spatially varying optical properties: it is translucent in regions where it should allow light passage to maintain imaging performance, and opaque or light-absorbing in regions where it should block light to prevent color mixing. This local differentiation of optical quality allows the partition wall to simultaneously achieve both light blocking and light transmission functions in different locations.
Solution Approach 2:
The partition wall structure is segmented into multiple functional layers with different optical properties. The translucent layer segments the light transmission path to allow useful light through, while the light-absorbing layer segments the reflected light path to absorb harmful high-angle light. This segmentation allows each layer to specialize in a specific function, achieving both contradictory requirements.
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 reduces high-angle incident light reaching the photoelectric conversion elements, thereby inhibiting color mixing and improving imaging performance by minimizing the conversion of flare light and other oblique light.
Implementation Method 1
the high-angle incident light that has reached the side surface of the first metal layer is attenuated while being repeatedly reflected between the side surface of the first metal layer and the first partition wall layer
Implementation Method 2
A refractive index of the second partition wall layer is larger than a refractive index of the first partition wall layer
Implementation Method 3
Each of the plurality of pixels is provided with a photoelectric conversion element that detects light and generates electrical charges
Data Source
AI summary
Provided are an imaging device and an electronic device configured such that deterioration in imaging performance due to high-angle incident light can be inhibited. The imaging device includes: a semiconductor substrate including a plurality of photoelectric conversion elements; a plurality of color filters that are provided on the semiconductor substrate and face each of the plurality of photoelectric conversion elements; and a partition wall that is provided on the semiconductor substrate and provides separation between one color filter and another color filter adjacent to each other among the plurality of color filters. The partition wall includes a first metal layer, a translucent first partition wall layer that covers a side surface of the first metal layer, and a translucent second partition wall layer located between the first metal layer and the first partition wall layer. A refractive index of the second partition wall layer is larger than a refractive index of the first partition wall layer.