Image Sensor Pixel Grid Structure for Phase Crosstalk Suppression
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Solution Overview
Problem
In highly integrated image sensing devices, light from phase detection pixels can penetrate adjacent image sensing pixels, leading to crosstalk and reduced light sensitivity, especially at smaller pixel sizes where metal light absorption layers are impractical.
Innovation Solution
The implementation of a grid structure with a black photoresist layer between phase detection and image sensing pixels, and an air layer between adjacent image sensing pixels, to absorb and prevent light penetration, respectively, while using a sacrificial carbon-containing layer and plasma process for manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metal light absorption layer is used to suppress light penetration, then light crosstalk is reduced, but device complexity and manufacturing difficulty increase at small pixel sizes
Solution Approach 1:
The patent uses a black photoresist layer as a temporary, disposable light absorption structure during manufacturing. This layer is formed using standard photolithography processes, is effective at blocking light, and can be selectively removed where not needed. It replaces complex metal light absorption layers with a simpler, process-integrated solution that is easier to manufacture at small pixel sizes.
Solution Approach 2:
The black photoresist layer is selectively formed only in specific regions where light crosstalk suppression is needed (between phase detection pixels and image sensing pixels), while being omitted in regions where it is not required. This localized application reduces overall device complexity while maintaining effective light suppression where necessary.
2Productivity
If pixel size is reduced to increase integration density, then more pixels fit in the sensor, but light sensitivity decreases due to increased crosstalk
Solution Approach 1:
The black photoresist layer acts as an intermediary structure between adjacent pixels, specifically between phase detection pixels and image sensing pixels. It provides a physical barrier that blocks light from leaking into neighboring pixels, enabling higher integration density without sacrificing light sensitivity. The air layer similarly serves as an optical intermediary that prevents light propagation between pixels.
Solution Approach 2:
The patent segments the sensor into distinct optical zones by introducing grid structures (black photoresist layers and air layers) that divide and isolate light paths between pixels. This segmentation prevents light from one pixel from affecting adjacent pixels, maintaining signal integrity even as pixel density increases.
3Object-affected harmful factors
If a black photoresist layer is formed between all pixels, then light crosstalk is suppressed, but manufacturing complexity increases due to additional patterning steps
Solution Approach 1:
The black photoresist layer is selectively formed only in specific regions where light crosstalk suppression is needed (between phase detection pixels and image sensing pixels), while being omitted in regions where it is not required. This localized application reduces overall device complexity while maintaining effective light suppression where necessary.
Solution Approach 2:
The black photoresist layer is formed as part of the color filter patterning process, utilizing the same photolithography steps already required for creating the color filter array. By integrating the light suppression structure formation into existing manufacturing steps, additional process complexity is minimized while still achieving the desired light crosstalk suppression.
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
Effectively suppresses light crosstalk between phase detection and image sensing pixels, maintaining high sensitivity even at small pixel sizes by selectively forming a black photoresist layer and omitting it where necessary, enhancing the performance of highly integrated pixel arrays.
Implementation Method 1
a first grid structure disposed between the adjacent first color filters and the second color filter and including a light absorption layer
Implementation Method 2
a second grid structure disposed between adjacent first color filters and structured to be free from the light absorption layer
Implementation Method 3
The removing the sacrificial layer pattern includes performing a plasma process using gas containing at least one of oxygen, nitrogen, or hydrogen on the first pattern and the second pattern covered with the capping layer pattern
Data Source
AI summary
An image sensing device includes a plurality of image sensing pixels configured to respond to light incident through first color filters and generate image signals corresponding to a target object to be captured, at least one phase detection pixel configured to respond to light incident through a second color filter and generate a phase signal for calculating a phase difference between images generated by the image signals, a first grid structure disposed between the adjacent first color filter and the second color filter and including a light absorption layer, and a second grid structure disposed between adjacent first color filters and structured to be free from the light absorption layer.