Image Sensor Protection Layer Convex Shape Crosstalk
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Solution Overview
Problem
Current image sensors face challenges in preventing optical crosstalk and optimizing signal-to-noise ratio due to overlapping micro lenses and optical losses from spaces between them.
Innovation Solution
An image sensor design featuring an air spacer between filters and a protection layer with a convex shape that expands vertically, preventing optical crosstalk and overlapping edges of micro lenses, while using micro lenses with refractive indices matching or lower than the protection layer to minimize optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If micro lenses are placed close together to increase pixel density, then productivity and area utilization improve, but optical crosstalk increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent divides the space between micro lenses by introducing air spacers that physically segment the optical path. This segmentation prevents light from adjacent pixels from mixing, thereby reducing optical crosstalk while maintaining high pixel density. The air spacers create distinct optical zones for each pixel element.
Solution Approach 2:
The patent introduces an intermediary substance (air spacer) between the micro lenses and filters. This intermediary material with refractive index close to air acts as a mediator that reduces optical coupling between adjacent pixels, preventing crosstalk while allowing the micro lenses to remain closely spaced for high pixel density.
2Reliability
If air spacer height is increased to prevent optical crosstalk, then signal-to-noise ratio improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the air spacer formation with the existing filter deposition process. The air spacers are formed by controlling the deposition of filter materials, integrating the crosstalk prevention structure into the existing manufacturing flow rather than adding separate complex structures. This reduces device complexity while maintaining effective optical isolation.
Solution Approach 2:
The patent optimizes the height parameter of the air spacer to achieve effective optical isolation without excessive height. By carefully controlling the spacer height within a specific range, the patent prevents optical crosstalk while avoiding the manufacturing complexities associated with taller structures, thus balancing reliability improvement with manageable device complexity.
3Strength
If protection layer is made thicker to protect micro lenses, then strength and durability improve, but optical losses increase and manufacturing precision requirements worsen
Solution Approach 1:
The patent optimizes the thickness parameter of the protection layer to achieve the minimum required strength while minimizing optical loss. By controlling the protection layer thickness within a specific optimal range, the patent ensures sufficient mechanical protection for the micro lenses without introducing excessive optical absorption or scattering losses.
Solution Approach 2:
The patent applies different properties to different regions: the protection layer has optimized thickness and material composition specifically tailored for the regions where micro lenses are located. This local optimization ensures adequate protection strength where needed while minimizing optical path interference, thereby reducing optical losses.
4Reliability
If micro lenses are made larger to improve light collection, then signal-to-noise ratio improves, but area utilization decreases and pixel density reduces
Solution Approach 1:
The patent uses air spacers to create optimized optical pathways that improve light collection efficiency without requiring larger micro lens areas. The air spacers facilitate better light guidance and reduction of optical losses, allowing smaller micro lenses to achieve the same light collection performance, thereby maintaining high pixel density.
Solution Approach 2:
The patent optimizes the size parameter of micro lenses in conjunction with air spacer dimensions to achieve efficient light collection within constrained areas. By coordinating the sizing of micro lenses with the air spacer configuration, the patent maximizes light gathering capability while maintaining high pixel density through compact design.
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 enhances the signal-to-noise ratio and performance of the image sensor by preventing optical crosstalk and minimizing optical losses, thereby improving overall image sensor performance.
Implementation Method 1
The plurality of filters may have a higher refractive index than the air spacer
Implementation Method 2
the micro lens may have the same refractive index as a protection layer, or a lower refractive index than a protection layer
Data Source
AI summary
An image sensor includes a plurality of filters, an air spacer formed between the plurality of filters, and a protection layer including a first part formed on the plurality of filters and a second part formed on the air spacer. The second part of the protection layer may have a convex lens shape that protrudes over the plurality of filters.