Pixel Capacitor Trench Layout for Low-Noise Image Sensors
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Solution Overview
Problem
Laminate-type image capture devices face challenges in reducing noise and miniaturization due to limitations in the layout of electrical connections and parasitic capacitance, which affect the quality and size of the imaging device.
Innovation Solution
The imaging device incorporates a first capacitive element with trench portions and multiple electrical contact points, allowing for increased freedom in wire layout, reduced parasitic capacitance, and enhanced capacitance value, while minimizing pixel area and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional laminate-type structure with photoelectric conversion layer on insulating layer is used, then the device can achieve basic imaging function, but parasitic capacitance increases and wire layout freedom is limited
Solution Approach 1:
The patent introduces trench portions that extend vertically into the substrate, utilizing the third dimension (depth) to create capacitive coupling paths. This allows electrical connections to be established through vertical trenches rather than only horizontal wire routing, thereby reducing parasitic capacitance in the planar direction while maintaining electrical connectivity.
Solution Approach 2:
The capacitive element is divided into multiple segments including first and second electrodes separated by dielectric layers, with trench portions creating distinct vertical zones. This segmentation allows independent optimization of each segment's electrical characteristics, enabling reduced parasitic capacitance while maintaining necessary capacitance values for noise reduction.
2Adaptability or versatility
If more electrical contact points are added to increase wire layout freedom, then layout flexibility improves, but device area increases
Solution Approach 1:
The patent utilizes vertical trenches extending into the substrate to create multiple electrical contact points at different depths. This three-dimensional approach allows multiple connections to be established within a compact planar footprint, increasing wire layout freedom without proportionally increasing pixel area.
Solution Approach 2:
The trench portions are nested within the pixel structure, with electrodes and dielectric layers arranged in concentric or nested configurations. This nesting allows multiple electrical contact points to be packed into a small area by utilizing vertical space and overlapping horizontal projections, thereby increasing layout flexibility without significant area penalty.
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 reduces noise and allows for miniaturization of the imaging device by minimizing parasitic capacitance and increasing the degree of freedom in wire layout, leading to improved image quality and smaller pixel sizes.
Implementation Method 1
a first capacitive element including a first electrode provided above the semiconductor substrate, a second electrode provided above the semiconductor substrate, and a dielectric layer located between the first electrode and the second electrode
Data Source
AI summary
An imaging device includes a semiconductor substrate and pixels. Each of the pixels includes a first capacitive element including a first electrode provided above the semiconductor substrate, a second electrode provided above the semiconductor substrate, and a dielectric layer located between the first electrode and the second electrode. At least one selected from the group consisting of the first electrode and the second electrode has a first electrical contact point electrically connected to a first electrical element and a second electrical contact point electrically connected to a second electrical element different from the first electrical element. The first capacitive element includes at least one trench portion having a trench shape.