Vertically Stacked Image Sensor Sub-Pixels for Hyperspectral Imaging
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Solution Overview
Problem
Existing image sensors face challenges in achieving high integration and hyperspectral imaging due to pixel size limitations, particularly with flatly arranged color filters, which hinder efficient wavelength separation and light absorption.
Innovation Solution
A vertically stacked type image sensor is developed, featuring pixels with sub-pixels of varying diameters and heights, each configured to generate absorption resonance at specific wavelengths, allowing for efficient wavelength separation and increased light absorptivity, with sub-pixels of different widths (red, green, and blue) stacked sequentially and inclined towards each other, and an insulating layer enhancing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are arranged in a mosaic form on the photodiode surface, then wavelength separation is achieved, but pixel size increases and integration density decreases
Solution Approach 1:
The patent transitions from a two-dimensional mosaic arrangement of color filters to a three-dimensional vertically stacked structure. Multiple photodiodes with different color filters are stacked in the vertical direction, allowing wavelength separation to occur through depth rather than lateral spacing. This dimensional change enables compact pixel design while maintaining spectral discrimination capability.
Solution Approach 2:
The patent implements a nested structure where multiple photodiodes with different color filters are stacked vertically within a single pixel footprint. Each photodiode is positioned at different heights, creating a nested configuration that maximizes the use of vertical space. This nesting approach allows multiple wavelength channels to be integrated within a minimal horizontal area.
2Quantity of substance
If photodiodes are stacked vertically with different color filters, then integration density increases, but light absorptivity decreases due to reduced path length
Solution Approach 1:
The patent introduces inclined side surfaces on the stacked photodiodes, creating a tapered or curved profile rather than straight vertical walls. This curvature increases the optical path length by bending light trajectories through the colored regions, enhancing absorption efficiency without increasing the horizontal footprint or compromising integration density.
3Ease of manufacture
If sub-pixels have uniform diameters, then manufacturing is simplified, but wavelength separation efficiency is reduced
Solution Approach 1:
The patent applies local quality by varying the diameters of different photodiodes within the stacked structure. Specifically, photodiodes positioned lower in the stack have larger diameters, while those higher up have smaller diameters. This non-uniform sizing optimizes light capture at different depths and enhances wavelength separation efficiency, with the trade-off managed through targeted 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
The solution enables enhanced wavelength separation and increased light absorptivity, overcoming pixel size limitations, allowing for higher integration and the capability to capture hyperspectral images without the need for additional filters, thereby improving image sensor efficiency and resolution.
Implementation Method 1
the plurality of sub-pixels have a layer structure that is configured to generate an absorption resonance at different wavelengths of light
Data Source
AI summary
Provided is a vertically stacked type image sensor including a plurality of pixels, each of the plurality of pixels including a plurality of sub-pixels stacked vertically, wherein the plurality of sub-pixels have a layer structure that is configured to generate an absorption resonance at different wavelengths of light.