Image Sensor Light-Shielding Film with Refractive Index Layer
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Solution Overview
Problem
Image sensing devices face issues with noise due to reflected light from metal light-shielding films entering photoelectric conversion portions, leading to undesirable signals and image degradation.
Innovation Solution
An image sensing device design featuring a light-shielding film with apertures for photoelectric conversion portions, where the film's upper surface and side wall are made of materials with controlled spectral reflectance, and a second film with a different refractive index is used between the light-shielding film and the substrate to minimize indirect incoming light, with a manufacturing method involving a Damascene process for embedding aluminum or tungsten in a silicon oxide-based layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metal light-shielding film is used to block light, then light shielding performance is improved, but reflected light enters photoelectric conversion portions causing noise
Solution Approach 1:
The patent introduces an intermediary layer between the metal light-shielding film and the photoelectric conversion portions to absorb or scatter reflected light. This intermediary structure prevents the harmful reflected light from directly entering the photoelectric conversion portions while maintaining the light-blocking function of the metal film.
Solution Approach 2:
The patent converts the harmful reflected light into a beneficial effect by designing the light-shielding film structure to redirect reflected light toward areas where it can be useful, such as toward color filters or other optical elements, thereby reducing noise while maintaining shielding effectiveness.
2Object-affected harmful factors
If the light-shielding film is placed close to the photoelectric conversion portions, then light blocking efficiency is improved, but reflected light more easily enters the photoelectric conversion portions
Solution Approach 1:
The patent addresses this contradiction by introducing a vertical dimension solution - placing a light-absorbing or light-scattering layer between the light-shielding film and photoelectric conversion portions. This layered approach in the vertical dimension allows the film to remain close for blocking efficiency while the intermediate layer captures reflected light.
3Illumination intensity
If a highly reflective material is used for the light-shielding film, then light reflection is improved, but more reflected light enters adjacent photoelectric conversion portions
Solution Approach 1:
The patent applies local quality by making different parts of the light-shielding structure have different optical properties. The light-shielding film maintains high reflectivity for its primary function, while adjacent light-absorbing layers or structured surfaces locally absorb or scatter the reflected light to prevent it from entering photoelectric conversion portions.
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 the impact of reflected light on image quality by minimizing indirect incoming light, resulting in improved image accuracy and color representation.
Implementation Method 1
a second film disposed between the first film and the substrate. The second film includes a first layer having a refractive index different from the first film. The first layer lies within at least the transit portions and forms interfaces with the first film.
Implementation Method 2
At least one of the upper surface and the side wall is made of a material having a maximum spectral reflectance for visible light of 75% or less. The material of the upper surface has a minimum spectral reflectance for visible light of 3⁄4 or more of the maximum.
Data Source
AI summary
An image sensing device includes a light-shielding film having transit portions, a first film and a second film. The second film comprises a first layer having a different refractive index from the first film. The first layer lies within at least the transit portions, and forms interfaces with the first film. The distance between the interface and the corresponding photoelectric conversion portion is greater than the distance between the photoelectric conversion portion and the lower end of the corresponding transit portion.