Air Layer Optical Grid Between Color Filters
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Solution Overview
Problem
CMOS image sensors face challenges with optical crosstalk and noise due to the proximity of color filters, which affects image quality and signal integrity.
Innovation Solution
Incorporating an optical grid structure with an air layer and capping films between adjacent color filters, featuring an open area connected to the outside, to optically isolate pixels and prevent crosstalk, while also distributing pressure to prevent structural damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If color filters are disposed adjacent to each other to increase pixel density, then productivity and area utilization are improved, but optical crosstalk between pixels increases and image quality deteriorates
Solution Approach 1:
An air layer is introduced as an intermediary substance between adjacent color filters to optically isolate them. The air layer acts as a refractive index barrier that prevents light from one pixel from leaking into adjacent pixels, thereby eliminating optical crosstalk while maintaining high pixel density. This mediator approach allows color filters to remain closely spaced without compromising image quality.
Solution Approach 2:
The air layer is selectively positioned only at the boundaries between adjacent color filters, creating local optical isolation where needed. The capping film structure is also locally configured to cover the air layer and maintain the isolated structure. This localized application of the air layer enables optical isolation precisely where crosstalk occurs without affecting the overall pixel array density or light transmission to the photodetectors.
2Object-affected harmful factors
If an air layer is formed between color filters to reduce optical crosstalk, then image quality is improved, but structural stability and resistance to pressure damage worsen
Solution Approach 1:
A capping film is formed over the air layer to create a flexible protective shell that maintains the air layer structure while withstanding external pressure. The thin film structure follows the contours of the air layer and provides mechanical support, preventing the air layer from collapsing under pressure during device operation or manufacturing processes. This shell structure preserves both the optical isolation function and structural integrity.
Solution Approach 2:
The capping film is formed beforehand to cover and protect the air layer structure before the device undergoes pressure-related manufacturing steps or operation. This pre-formed protective layer cushions the air layer against potential pressure damage, preventing structural failure before it can occur. The capping film acts as a preventive measure that maintains the air layer's structural stability throughout the device lifecycle.
3Object-affected harmful factors
If a stable grid structure with air layer is implemented, then optical isolation and image quality are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The capping film formation process is merged with the existing color filter fabrication sequence, integrating the air layer creation and protection steps into the standard manufacturing flow. The capping film is deposited in the same processing chamber and using similar techniques as other dielectric layers in the device, combining multiple functions into a unified manufacturing step. This merging approach reduces the number of separate process modules needed despite the added structural element.
Solution Approach 2:
The air layer structure is self-formed through the fabrication process itself, where the capping film deposition automatically creates the protective shell around the air-filled spaces. The structure serves its own protective function without requiring additional external support elements or complex assembly steps. The air layer and capping film work together as a self-sufficient system that maintains optical isolation while withstanding pressure, eliminating the need for separate reinforcement structures.
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 effectively reduces optical crosstalk and enhances image quality by isolating pixels and managing pressure distribution, thereby improving the stability and performance of the image sensing device.
Implementation Method 1
an air layer formed between the color filters and a first capping film structured to cover the air layer
Data Source
AI summary
Image sensing devices are disclosed. In an aspect, an image sensing device may include an array of sensor pixels to detect incident light to output pixel signals indicative of an image of the incident light, color filters respectively formed over the sensor pixels to filter light incident to the sensor pixels, respectively, and one or more optical grid structures disposed between adjacent color filters. Each of the one or more optical grid structures may include an air layer formed between the color filters and a first capping film structured to cover the air layer and having an open area formed over the air layer and connected to an outside of the color filters.