Image Sensor Isolation Layer Depth for Noise Reduction
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Solution Overview
Problem
Image sensors face noise issues due to light incident angle variations, particularly affecting green pixels located near the edge regions of the pixel array, which impact imaging quality.
Innovation Solution
The implementation of an image sensor with an isolation layer of varying depths surrounding green pixels in a Bayer pattern color filter array, where the depth of the isolation layer is adjusted to minimize light leakage and optimize signal-to-noise ratio by increasing the depth around green pixels adjacent to red pixels and decreasing it around those adjacent to blue pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the isolation layer depth is increased to reduce light leakage and noise, then the signal-to-noise ratio is improved, but the manufacturing complexity and device structure become more complex
Solution Approach 1:
The patent applies local quality by setting different isolation layer depths for different pixel types within the same pixel array. Specifically, first pixels (e.g., red or blue pixels) have a first isolation layer depth, while second pixels (e.g., green pixels) have a second isolation layer depth that is greater than the first. This localized differentiation optimizes noise reduction for specific pixels without unnecessarily complicating the entire device structure, thereby improving signal-to-noise ratio while controlling manufacturing complexity.
2Manufacturing precision
If the isolation layer depth is varied to optimize noise reduction for specific pixels, then imaging quality is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent segments the pixel array into different pixel types (first pixels and second pixels) with different isolation layer depth requirements. This segmentation allows the manufacturing process to target specific pixel regions for enhanced isolation, rather than uniformly increasing isolation layer depth across the entire array. The segmented approach reduces overall manufacturing precision requirements while still achieving the necessary noise reduction for critical pixels.
Solution Approach 2:
By applying different isolation layer depths only to specific pixel types locally, the patent reduces the overall manufacturing precision burden. Instead of requiring high precision across the entire array, only specific regions (second pixels) require the deeper isolation layers, making the fabrication process more manageable while maintaining imaging quality.
3Reliability
If deeper isolation layers are used for all pixels to minimize noise, then image quality is improved, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent implements local quality by selectively applying deeper isolation layers only to second pixels (e.g., green pixels) that require enhanced noise reduction, while maintaining standard isolation layer depth for first pixels. This localized approach achieves effective noise reduction where needed without unnecessarily increasing the complexity of the overall device structure, thereby improving reliability while avoiding excessive device complexity.
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 effectively reduces noise in image sensors by adjusting the signal change components of green pixels, thereby enhancing imaging performance and maintaining sensitivity.
Implementation Method 1
an isolation layer formed to surround the first pixel in the pixel array and structured to have a first depth, and an isolation layer formed to surround the second pixel in the pixel array and structured to have a second depth different from the first depth
Data Source
AI summary
An image sensor is disclosed. The image sensor includes a first pixel of a first color arranged alternately with a pixel of a second color in a first direction of a pixel array, a second pixel of the first color arranged alternately with a pixel of a third color in the first direction in a row different from that of the first pixel of the first color, an isolation layer formed to surround the first pixel in the pixel array and structured to have a first depth, and an isolation layer formed to surround the second pixel in the pixel array and structured to have a second depth different from the first depth. One of the first and second pixels of the first color, and each of the pixels of the second color and the third color are configured to selectively receive different colors of light, respectively.