Image Sensor Capacitor Nested Electrodes Charge Loss
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Solution Overview
Problem
Current image sensors face challenges in achieving high performance and efficient global shutter operation, particularly in reducing charge loss and noise generation during image capture.
Innovation Solution
The image sensor design incorporates a semiconductor substrate with a photoelectric conversion layer, transistors, and capacitors, including a unique arrangement of lower electrodes and capacitors to enhance capacitance and reduce noise, allowing for efficient global shutter operation by increasing the surface area and capacitance of the capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitor size is increased to reduce charge loss and noise, then the capacitance and signal quality improve, but the pixel area and device complexity increase
Solution Approach 1:
The capacitor structure is designed with nested electrodes where a first lower electrode is positioned within a second lower electrode, and an upper electrode is positioned above them. This nested arrangement maximizes the effective capacitance within a confined pixel area, allowing the capacitor to store more charge without proportionally increasing the overall device footprint or structural complexity.
Solution Approach 2:
The capacitor design extends into the vertical dimension by stacking multiple electrodes at different heights (first lower electrode, second lower electrode, and upper electrode) rather than simply expanding the capacitor footprint in the horizontal plane. This three-dimensional electrode arrangement increases capacitance while maintaining a compact pixel layout.
2Object-generated harmful factors
If the capacitor surface area is increased to enhance capacitance, then the noise generation is reduced, but the pixel region area occupied increases
Solution Approach 1:
The nested electrode configuration allows the capacitor to achieve increased effective surface area for charge storage without proportionally increasing the projected pixel area. The electrodes are arranged concentrically and vertically, maximizing the capacitance-generating surface while maintaining a compact footprint that fits within the pixel region constraints.
Solution Approach 2:
By utilizing the vertical dimension with stacked electrodes at different heights, the capacitor achieves increased effective surface area for noise reduction without expanding the horizontal pixel footprint. The first lower electrode, second lower electrode, and upper electrode are positioned at different vertical levels, creating a three-dimensional capacitance structure.
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 design improves shutter efficiency by reducing charge loss and noise generation, enabling high-performance image capture with increased capacitance and improved signal quality.
Implementation Method 1
a photoelectric conversion layer in the semiconductor substrate
Data Source
AI summary
An image sensor includes a semiconductor substrate having a first surface and a second surface opposite to the first surface, a photoelectric conversion layer in the semiconductor substrate, transistors on the first surface of the semiconductor substrate, a first interlayer insulation layer on the transistors, a first lower pad electrode and a second lower pad electrode spaced apart from the first lower pad electrode on the first interlayer insulation layer, a mold insulation layer on the first and second lower pad electrodes, first and second lower electrodes in the mold insulation layer, a dielectric layer on the first and second lower electrodes, an upper electrode on the dielectric layer, and an upper pad electrode connected to the upper electrode and including a different conductive material from the first and second lower pad electrodes. The first lower electrodes are on the first lower pad electrode, and the second lower electrodes are on the second lower pad electrode.