Image Sensor Trenched Filler Grid Reflective Layer Crosstalk
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Solution Overview
Problem
Image sensors face issues with light signal decay and crosstalk due to light traveling through dielectric layers and being detected by incorrect photodiodes, leading to degraded performance and increased noise.
Innovation Solution
The implementation of a filler grid over a dielectric grid and a reflective layer that guides light to specific photodiodes, reducing light propagation through dielectric layers and minimizing crosstalk by forming trenches in the dielectric layer and using a reflective layer to channel light correctly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light propagates through dielectric layers to reach photodiodes, then the image sensor can detect light, but light signal decay occurs and crosstalk increases
Solution Approach 1:
A reflective layer is introduced as an intermediary between the dielectric grid and the photodiodes. This reflective layer redirects light that would otherwise be lost or cause crosstalk, directing it toward the intended photodiode. The reflective layer acts as a mediator that improves light detection accuracy while preventing signal decay and reducing crosstalk between adjacent photodiodes.
2Stability of the object's composition
If a dielectric grid is used to support the structure, then mechanical stability is provided, but light signal decay and crosstalk occur
Solution Approach 1:
The reflective layer serves as a mediator between the dielectric grid and the photodiodes, resolving the contradiction between structural stability and light detection accuracy. It allows the dielectric grid to maintain its structural support function while the reflective layer ensures proper light guidance, preventing crosstalk and signal decay without compromising the mechanical stability provided by the dielectric grid.
3Reliability
If the reflective layer is formed over the entire dielectric grid, then light guidance is improved, but manufacturing complexity increases
Solution Approach 1:
The reflective layer is applied selectively rather than uniformly across the entire dielectric grid. By applying the reflective layer only in specific regions where light guidance is needed, the patent improves light detection accuracy while minimizing the increase in manufacturing complexity. This localized approach allows for targeted light management without requiring complex manufacturing processes across the entire sensor surface.
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 configuration mitigates light signal decay and crosstalk, enhancing the signal-to-noise ratio by ensuring light reaches the intended photodiodes with reduced signal loss and incorrect detection, thereby improving image sensor performance.
Implementation Method 1
a reflective layer that guides light to specific photodiodes, reducing light propagation through dielectric layers and minimizing crosstalk
Data Source
AI summary
Among other things, one or more image sensors and techniques for forming such image sensors are provided. An image sensor comprises a photodiode array configured to detect light. A filler grid is formed over the photodiode array, such as over a dielectric grid. The filler grid comprises one or more filler structures, such as a first filler structure that provides a light propagation path to a first photodiode that is primarily through the first filler structure. In this way, signal strength decay of light along the light propagation path before detection by the first photodiode is mitigated. The image sensor comprises a reflective layer that channels light towards corresponding photodiodes. For example, a first reflective layer portion guides light towards the first photodiode and away from a second photodiode. In this way, crosstalk, otherwise resulting from detection of light by incorrect photodiodes, is mitigated.