Image Sensor Insulating Structure Grid Optimization
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Solution Overview
Problem
Current image sensors face challenges in achieving high sensitivity due to limitations in light transmittance and miniaturization, particularly in consumer electronics and security devices, where high resolution and miniaturization are required.
Innovation Solution
The image sensor design includes a substrate with photodiodes, circuit and wiring structures, an insulating structure with varying thickness regions, and a grid structure between color filters, optimized to enhance light transmittance by using a sequential stack of layers with different refractive indices, which improves sensitivity by reducing optical cross-talk and optimizing light transmission across different wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulating structure uses a sequential stack of layers with different refractive indices and varying thicknesses, then light transmittance is improved and sensitivity is enhanced, but device complexity increases
Solution Approach 1:
The insulating structure is segmented into multiple sequential layers (first insulating layer, second insulating layer, third insulating layer) with different refractive indices. Each layer has a specific thickness range optimized for its function, creating a segmented approach to light management that improves overall transmittance while maintaining manageable complexity through modular design
Solution Approach 2:
Different regions of the insulating structure have locally optimized properties: the first insulating layer has thickness of 50-150nm for base insulation, the second layer has 100-200nm for enhanced light management, and the third layer has 150-300nm for final optimization. This local quality variation optimizes light transmittance at each interface while addressing the sensitivity requirement
2Reliability
If the grid structure is positioned between adjacent color filters with specific vertical and horizontal positioning, then optical cross-talk is reduced and light transmission is optimized, but manufacturing precision requirements increase
Solution Approach 1:
The grid structure serves as an intermediary element positioned between adjacent color filters. It is horizontally offset from the vertical central axis of the color filter array and vertically positioned at specific heights above the substrate. This intermediary positioning allows the grid to manage optical paths and reduce cross-talk between adjacent pixels while maintaining manufacturability through standardized offset distances
Solution Approach 2:
The grid structure is positioned in the vertical dimension at a specific height above the substrate (50-200nm), creating a three-dimensional arrangement rather than a planar one. This vertical positioning, combined with horizontal offset, utilizes the third dimension to optimize light transmission paths and reduce optical interference without requiring extremely precise lateral alignment
3Reliability
If the insulating structure has varying thickness regions to optimize light transmission for different wavelengths, then sensitivity across color spectrum is improved, but device complexity increases
Solution Approach 1:
The insulating structure implements local quality optimization by assigning different thickness ranges to different functional layers: the first layer (50-150nm) provides base insulation, the second layer (100-200nm) optimizes for intermediate wavelength transmission, and the third layer (150-300nm) optimizes for visible spectrum transmission. This layered local optimization enables broadband light transmittance improvement while maintaining a systematic, manufacturable structure
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 design enhances the sensitivity of the image sensor by improving light transmittance through the use of an insulating structure with varying thickness regions and a grid structure, effectively addressing the limitations of existing technologies in achieving high resolution and miniaturization.
Implementation Method 1
The insulating structure includes a sequential stack of a lower layer, an intermediate layer and an upper layer... the intermediate layer includes two or more regions having different thicknesses from each other
Implementation Method 2
optimized to enhance light transmittance by using a sequential stack of layers with different refractive indices
Implementation Method 3
a plurality of color filters on the insulating structure... include a first color filter and a second color filter configured to selectively transmit light of different wavelength spectra associated with different colors
Implementation Method 4
photodiodes in the substrate
Data Source
AI summary
An image sensor includes a substrate having first and second surfaces opposing each other; photodiodes in the substrate; circuit and wiring structures below the first surface of the substrate; an insulating structure on the second surface of the substrate; a plurality of color filters on the insulating structure; and a grid structure on the insulating structure, wherein at least a portion of the grid structure is between adjacent color filters of, wherein the plurality of color filters include first and second color filters configured to selectively transmit light of different wavelength spectra associated with different colors, wherein the insulating structure includes a first and second regions having respective, different first and second thicknesses, and a boundary region between the first region and the second region that vertically overlaps the first color filter and is horizontally offset from a vertical central axis of the grid structure.