Shared MIM Capacitor Electrodes in Miniaturized Image Sensor Pixels
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS image sensors face challenges in configuring efficient wiring for metal-insulator-metal (MIM) capacitors within miniaturized pixels, which limits their capacitance and performance in both low-light and high-light environments.
Innovation Solution
The image sensor design incorporates overlapping electrodes with a dielectric layer for MIM capacitors, allowing for shared electrodes between adjacent pixels, thereby increasing capacitor area and capacitance, and includes a dual conversion gain transistor to enhance charge transfer and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MIM capacitors are implemented to improve capacitance of floating diffusion zones, then capacitance is improved, but wiring area increases which conflicts with miniaturized pixel requirements for high resolution
Solution Approach 1:
Adjacent pixels share common second electrodes and dielectric layers, merging previously separate capacitor structures. This integration reduces redundant wiring and allows MIM capacitors to be formed within miniaturized pixel areas while maintaining improved capacitance performance.
Solution Approach 2:
The second electrodes and dielectric layers serve dual purposes: they form part of the MIM capacitor structure for improved capacitance while simultaneously acting as shared components between adjacent pixels. This multi-functionality enables both high capacitance and high resolution in the same pixel structure.
2Manufacturing precision
If pixel size is reduced to provide high resolution, then resolution is improved, but available area for capacitor wiring is reduced
Solution Approach 1:
The MIM capacitor structure is nested within the miniaturized pixel by utilizing overlapping electrode configurations and shared layers between adjacent pixels. The second electrodes and dielectric layers are positioned to serve both capacitor functions and pixel integration, effectively nesting the capacitor within the limited pixel area.
Solution Approach 2:
The capacitor structure transitions from a planar two-dimensional layout to a three-dimensional overlapping electrode configuration. By stacking electrodes and dielectric layers vertically and utilizing shared structures between pixels, the capacitor achieves sufficient capacitance within the reduced horizontal pixel area.
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 enables efficient operation in various lighting conditions while maintaining high resolution, improving the capacitance of floating diffusion zones and enhancing the overall performance of the image sensor.
Implementation Method 1
a photovoltaic device configured to convert incident light into charge
Data Source
AI summary
The present disclosure relates to an image sensor, and the image sensor of the present disclosure may include a plurality of pixels, each of which includes a photovoltaic device configured to convert incident light into charge, and a capacitor configured to store the charge, the capacitor of each of the plurality of pixels may include a first electrode and a second electrode that overlap each other, and a dielectric layer that is between the first electrode and the second electrode, the plurality of pixels may include a first pixel and a second pixel adjacent to each other, and the second electrode of the first pixel and the second electrode of the second pixel may be integral with each other.