Image Sensor PD Bias Patterns for Color Separation
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Solution Overview
Problem
As image sensors require higher resolution and smaller pixel sizes, there is a need to reduce the physical volume of photodiodes while maintaining the capability to generate photoelectrons effectively, especially in capturing multiple colors with a single photodiode.
Innovation Solution
The design incorporates conductive photodiode bias patterns around a photodiode region, with a floating diffusion region and transfer gates to manage and transfer photoelectrons, allowing for the creation of multiple effective photodiode regions by applying different voltages, enabling the capture of multiple colors using a single photodiode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the physical volume of photodiode is reduced to increase resolution and decrease pixel size, then the resolution and pixel density are improved, but the capability for generating photoelectron deteriorates
Solution Approach 1:
The photodiode region is divided into multiple segments by introducing bias patterns that create separate photoelectron generation zones. Each segment can independently generate photoelectrons, allowing the total photoelectron generation capability to be maintained even as the overall photodiode area is reduced for higher resolution.
Solution Approach 2:
Different regions within the photodiode are given different electrical characteristics through bias patterns. By applying different voltages to different local regions, the patent optimizes photoelectron generation in each local area, ensuring effective performance despite the reduced overall size of the photodiode.
2Device complexity
If multiple colors are captured using a single photodiode, then the device complexity is reduced, but the ability to differentiate between colors deteriorates
Solution Approach 1:
The patent uses dynamically controllable bias patterns that can change voltage levels in real-time. By dynamically adjusting the bias voltages on different photodiode regions, the system can selectively enhance sensitivity to different wavelengths, enabling color differentiation with a single photodiode structure.
Solution Approach 2:
The patent changes electrical parameters (voltage levels) of different photodiode regions to optimize their spectral response. By varying bias voltages, the photodiode's sensitivity to different colors can be modulated, allowing a single photodiode to differentiate between multiple colors through parameter control rather than structural 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 enhances the light receiving capability and photoelectron generation, allowing the image sensor to effectively capture and differentiate between various colors, improving overall image sensing performance.
Implementation Method 1
a photosensing region in a substrate and configured to generate photoelectrons in response to incident light on the photosensing region
Data Source
AI summary
An image sensor is disclosed. The image sensor may include a photosensing region in a substrate and configured to generate photoelectrons in response to incident light on the photosensing region; bias patterns arranged to surround the photosensing region and including a conductive material; a floating diffusion region at a center of the photosensing region to store photoelectrons generated by the photosensing region; and transfer gates that partially overlap with the floating diffusion region and are operable to transfer photoelectrons generated by the photosensing region to the floating diffusion region. The photosensing region and the bias patterns are electrically isolated from one another.