Image Sensor Grid Pattern for Crosstalk and Shading Control
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Solution Overview
Problem
Image sensors face challenges in preventing optical crosstalk and shading variations due to differences in incident light quantity across the pixel array, particularly exacerbated by the increase in Chief Ray Angle (CRA), which affects image quality.
Innovation Solution
The image sensor incorporates a grid pattern with a trapezoidal cross-section, featuring a vertical side surface facing the incident light direction and an inclined side surface opposite to it, with internal angles optimized to correspond to the CRA, ensuring a minimum line width to prevent optical crosstalk and varying line widths to manage shading variations effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a grid pattern with uniform line width is used to prevent optical crosstalk, then optical crosstalk is reduced, but shading variations increase due to CRA differences across pixel array
Solution Approach 1:
The grid pattern implements local quality by varying the line width according to the Chief Ray Angle (CRA) at different positions in the pixel array. Pixels at the center have smaller line widths while pixels at the edges have larger line widths, optimizing each region's light reception characteristics to compensate for CRA-induced shading variations while maintaining optical crosstalk prevention
Solution Approach 2:
The invention changes the geometric parameter of the grid pattern (line width) as a function of position in the pixel array. The line width is systematically adjusted based on the CRA characteristics at each location, transforming the grid pattern from a uniform structure to a non-uniform structure that adapts to local optical conditions
2Object-affected harmful factors
If the line width of grid pattern is increased to prevent optical crosstalk, then optical crosstalk is reduced, but light loss increases reducing quantum efficiency
Solution Approach 1:
The grid pattern applies local quality by setting different line widths for different pixel regions. Pixels at the center of the array have smaller line widths to minimize light loss and maximize quantum efficiency, while pixels at the edges have larger line widths to prevent optical crosstalk, thus optimizing the balance between these two competing requirements locally
3Productivity
If CRA is increased to improve pixel array coverage, then more pixels can be packed, but shading variations and optical crosstalk worsen
Solution Approach 1:
The grid pattern implements local quality by adapting its line width to the local CRA conditions created by high pixel density packing. Pixels experiencing higher CRA due to edge positioning or dense packing have larger line widths, while central pixels have smaller line widths, thereby compensating for the adverse effects of increased CRA on shading and crosstalk
Solution Approach 2:
The invention changes the grid pattern's geometric parameters (line width) as a function of position in the pixel array, which is itself determined by the CRA distribution resulting from the pixel array configuration. This creates a feedback loop where the grid pattern adapts to the optical conditions created by high-density packing
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 enhances quantum efficiency by preventing optical crosstalk and reducing light loss, thereby improving image quality by minimizing shading variations across the pixel array.
Implementation Method 1
a substrate including a photoelectric conversion element
Data Source
AI summary
An image sensor may include a substrate having a photoelectric conversion element and a grid pattern formed over the substrate and having a flat upper surface, a first side surface, and a second side surface, wherein the first side surface and the second side are located opposite to each other. A first internal angle is formed between the flat upper surface and the first side surface, a second internal angle is formed between the flat upper surface and the second side surface, and the first internal angle may be smaller than the second internal angle.