Nano-Post Image Sensor Layout for Color Separation and Low Crosstalk
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Solution Overview
Problem
Current image sensors face challenges in maximizing light utilization efficiency and minimizing cross-talk between pixels, which affects their sensitivity and auto-focus capabilities.
Innovation Solution
The image sensor incorporates a color separating lens array with nano-posts spaced apart on a spacer layer, along with a deep device isolation pattern that extends into each pixel region, allowing for efficient separation of incident light wavelengths and reducing interference between photoelectric conversion regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are used to sense colors of incident light, then color detection capability is improved, but light utilization efficiency deteriorates due to absorption of light of other colors
Solution Approach 1:
The incident light is segmented by wavelength using a color separating lens array that directs different wavelengths to different pixel regions. This replaces the conventional color filter approach where each filter absorbs non-matching wavelengths, with a system that physically separates and directs wavelengths, thereby improving light utilization efficiency while maintaining color detection capability.
Solution Approach 2:
A color separating lens array is introduced as an intermediary optical element between the incident light and the pixel regions. This lens array uses diffractive or refractive properties to separate colors and adjust directionality according to wavelength, enabling efficient light routing without the energy loss associated with color filter absorption.
2Measurement precision
If pixels are arranged closely to increase resolution, then image quality is improved, but cross-talk between pixels increases reducing sensitivity
Solution Approach 1:
The harmful optical interference between adjacent pixels is extracted and removed by introducing a deep device isolation pattern. This isolation structure extends into the substrate between pixel regions, effectively blocking stray light and preventing cross-talk, thereby maintaining pixel sensitivity even when pixels are closely arranged for high resolution.
3Ease of manufacture
If conventional device isolation is used between pixels, then manufacturing simplicity is maintained, but cross-talk between pixels increases affecting sensitivity
Solution Approach 1:
A deep device isolation pattern is formed preliminarily between pixel regions before final pixel fabrication. This isolation structure extends deep into the substrate and prevents cross-talk between pixels, ensuring high pixel sensitivity while maintaining compatibility with conventional manufacturing processes.
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 light efficiency, improves pixel sensitivity, and enables auto-focus functionality by minimizing cross-talk between pixels, thereby optimizing image sensing performance.
Implementation Method 1
The color separating element may separate colors of incident light by using diffractive or refractive properties of lights having different wavelengths
Implementation Method 2
The color separating element may separate colors of incident light by using diffractive or refractive properties of lights having different wavelengths
Implementation Method 3
The photodiode may convert incident light into an electrical signal
Data Source
AI summary
An image sensor includes a substrate having a first surface and a second surface which are opposite to each other, the substrate comprising a plurality of pixel regions arranged in a first direction and a second direction which are parallel to the first surface and intersect each other, a deep device isolation pattern extending into the substrate and between the plurality of pixel regions, and a color separating lens array on the second surface of the substrate. The color separating lens array includes a spacer layer on the second surface of the substrate, and a plurality of nano-posts horizontally spaced apart from each other on the spacer layer.