Nano-Post Color Separation in Image Sensors to Reduce Pixel Cross-Talk
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Solution Overview
Problem
Conventional 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 on a substrate, along with a deep device isolation pattern, to separate incident light by wavelength and prevent interference between pixel regions, enhancing light efficiency and auto-focus functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If color filters are used to sense colors of incident light, then color separation is achieved, but light utilization efficiency is reduced
Solution Approach 1:
The patent changes the physical parameter approach from absorption-based color filtering to refraction-based wavelength separation. By utilizing the refractive index differences of the color separating element at different wavelengths, the system achieves color separation without absorbing light, thereby improving light utilization efficiency while maintaining color separation accuracy
Solution Approach 2:
The patent replaces the conventional color filter mechanism (absorption) with a diffractive/refractive optical element. The color separating element uses diffraction and refraction physics to spatially separate wavelengths, substituting the absorption mechanism and enabling more efficient light utilization
2Productivity
If pixel regions are placed close together to increase density, then sensor resolution is improved, but cross-talk between pixels increases
Solution Approach 1:
The patent introduces deep device isolation patterns that extend into the substrate between adjacent pixel regions. This segmentation approach physically divides the pixel regions using insulating materials, preventing optical and electrical cross-talk while maintaining high pixel density arrangement
Solution Approach 2:
The patent extends the isolation structure into the depth dimension of the substrate rather than relying solely on lateral separation. By creating deep isolation trenches that extend vertically into the substrate, the patent effectively separates pixel regions in the third dimension, enabling closer lateral spacing without cross-talk
3Ease of manufacture
If conventional device isolation is used between pixel regions, then manufacturing is simplified, but cross-talk inhibition is insufficient
Solution Approach 1:
The patent performs preliminary isolation by extending device isolation patterns into the substrate before final pixel region formation. This preliminary deep isolation structure is established early in the manufacturing process, creating effective cross-talk barriers that simplify subsequent fabrication steps while ensuring adequate pixel separation
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 improves pixel sensitivity and reduces cross-talk, enabling better light utilization and auto-focus performance in image sensors.
Implementation Method 1
The color separating element may be configured to separate different colors of incident light by using diffractive or refractive properties of the color separating element at different wavelengths
Implementation Method 2
The color separating element may be configured to adjust a direction of the incident light according to a wavelength of the incident light by virtue of a refractive index and shape of the color separating element
Implementation Method 3
The photodiode may convert incident light into an electrical signal
Data Source
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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 array on the second surface of the substrate. The color separating 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.