Image Sensor Grid Structure With Air Gap for Crosstalk Reduction
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Solution Overview
Problem
As the number of pixels in image sensors increases and pixel size decreases, existing methods struggle to effectively form devices within the pixels to provide efficient pixel circuits, leading to challenges in reducing optical crosstalk and improving light sensitivity.
Innovation Solution
The image sensor incorporates a grid structure with an air gap defined by spacer layers and a capping layer, which separates color filters and includes a microlens to enhance light sensitivity and reduce optical crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased and pixel size is decreased, then the resolution is improved, but optical crosstalk between adjacent pixels increases
Solution Approach 1:
The patent introduces a grid structure that divides the pixel array into isolated regions. The grid structure includes vertical and horizontal lines that create separate zones for adjacent pixels, preventing optical interference between them. This segmentation approach maintains high resolution while eliminating crosstalk by physically partitioning the optical paths of neighboring pixels.
Solution Approach 2:
The grid structure acts as an intermediary element positioned between adjacent pixels. This intermediate structure blocks stray light from reaching neighboring pixels, thereby preventing optical crosstalk while allowing the high-density pixel arrangement to maintain its resolution advantage.
2Measurement precision
If the number of pixels is increased and pixel size is decreased, then the resolution is improved, but light sensitivity deteriorates
Solution Approach 1:
The grid structure segments the optical path to reduce light loss from crosstalk. By preventing stray light from interfering with adjacent pixels, more light energy is effectively utilized for image capture, thereby improving light sensitivity despite the smaller pixel size.
3Object-generated harmful factors
If a grid structure is introduced to reduce optical crosstalk, then optical crosstalk is reduced, but device complexity increases
Solution Approach 1:
The grid structure merges the functions of crosstalk reduction and structural support into a single integrated element. By combining these functions, the patent reduces the need for additional separate components, thereby limiting the increase in device complexity while effectively addressing optical crosstalk.
4Object-generated harmful factors
If a grid structure with air gap is introduced to reduce optical crosstalk, then optical crosstalk is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The air gap within the grid structure serves as an intermediary space that provides optical isolation between pixels. This air gap acts as a natural barrier to light propagation, reducing crosstalk while the grid structure provides the mechanical framework to maintain the gap, thereby balancing manufacturing requirements with optical performance.
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 grid structure with an air gap effectively reduces optical crosstalk and enhances light sensitivity by minimizing interference between color filters, improving the overall performance of the image sensor.
Implementation Method 1
The grid structure with an air gap effectively reduces optical crosstalk and enhances light sensitivity by minimizing interference between color filters
Implementation Method 2
a microlens on the grid structure
Data Source
AI summary
An image sensor includes photoelectric conversion devices in a substrate; a separation structure in the substrate and between the photoelectric conversion devices; an insulating structure on the substrate and the separation structure; color filters on the insulating structure; and a grid structure on the insulating structure and between the color filters. The grid structure includes spacer layers and a capping layer. The spacer layers have first surfaces opposing each other. The spacer layers define an air gap between the first surfaces that oppose each other. The capping layer covers second surfaces and upper surfaces of the spacer layers, and defines an upper limit of the air gap. The spacer layers have a first thickness, and the capping layer has a second thickness less than the first thickness.