Image Sensor Pixel Isolation With Light Modulator for Sharp Imaging
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Solution Overview
Problem
Current image sensors face challenges in achieving sharp images due to limitations in pixel isolation and light management, leading to issues like blooming and reduced quantum efficiency.
Innovation Solution
The image sensor design incorporates a substrate with pixel groups, a pixel isolation structure, a light-shield grid, and a light modulator, where the light modulator has a greater width than the light-shield grid, and is strategically positioned to prevent light from incident on the polysilicon pattern, enhancing quantum efficiency and autofocus functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel isolation structure is used, then pixel separation is achieved, but light loss occurs and quantum efficiency is reduced
Solution Approach 1:
A light modulator is introduced as an intermediary component positioned between the incident light and the polysilicon pattern in the pixel isolation structure. This light modulator selectively modulates light to prevent direct illumination of the polysilicon pattern, thereby reducing light loss and improving quantum efficiency without compromising pixel separation functionality
Solution Approach 2:
The optical properties of the pixel isolation structure are modified by adding the light modulator layer, which changes the light interaction parameters. This allows the structure to maintain its isolation function while reducing harmful light absorption by the polysilicon pattern, thus improving quantum efficiency
2Productivity
If pixel groups are arranged closely to increase pixel density, then productivity is improved, but blooming occurs between adjacent pixels
Solution Approach 1:
The harmful blooming effect is extracted and prevented by the light modulator that selectively blocks light from reaching the polysilicon patterns that would otherwise cause blooming between closely spaced pixels. This allows high pixel density arrangement while maintaining pixel isolation integrity
Solution Approach 2:
The polysilicon pattern in the pixel isolation structure, which normally causes light absorption and blooming, is converted into a beneficial element by using the light modulator to control light interaction. The structure transforms potential harm into benefit by enabling close pixel packing without blooming through selective light modulation
3Object-affected harmful factors
If a light-shield grid is used to block light, then blooming is reduced, but optical loss increases and quantum efficiency decreases
Solution Approach 1:
Instead of using a comprehensive light-shield grid that blocks light across entire pixel regions, the light modulator applies localized light blocking only at specific positions where polysilicon patterns are located. This selective approach reduces blooming while minimizing optical loss in active pixel regions, thereby improving quantum efficiency
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 improves quantum efficiency, increases photosensitivity, and enables the capture of sharp images while providing an excellent autofocus function by effectively managing light and reducing optical loss.
Implementation Method 1
a light modulator on the first surface and overlapping the intra-pixel group isolation of the pixel isolation structure at a center of each pixel group of the plurality of first to third pixel groups
Implementation Method 2
a microlens on a region where the color filter, the light-shield grid, and the light modulator are disposed
Implementation Method 3
Each of the pixels includes a photodiode. The photodiode serves to transform incident light rays into electrical signals
Data Source
AI summary
An image sensor comprising a substrate having first and second surfaces opposite to each other, a pixel isolation section that penetrates the substrate and separates a plurality of pixels constituting first, second, and third pixel groups, each of the first, second, and third pixel groups including pixels that are arranged in n columns and m rows, a light-shield grid on the first surface and overlapping the pixel isolation section, and a light modulator on the first surface and overlapping the pixel isolation section on a center of each of the first, second, and third pixel groups. The light-shield grid has a first width in a first direction. The light modulator has a second width greater than the first width in the first direction.