Through-Wiring Shielding Layout for Low-Capacitance Image Sensors
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Solution Overview
Problem
In solid-state imaging devices, stray capacitance associated with through-wiring increases, leading to decreased photoelectric conversion efficiency and image signal quality, while attempts to reduce capacitance by increasing the distance between through-wiring and the semiconductor substrate result in increased footprint, compromising pixel region security.
Innovation Solution
A solid-state imaging device configuration that includes a substrate with a first and second surface, a first through-wiring penetrating from the first surface to the second surface, an electroconductive body formed along the periphery of the first through-wiring with a dielectric body in between, and a voltage supply circuit that maintains a small voltage difference between the first through-wiring and the electroconductive body during charge transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance of separation between the through-wiring and the semiconductor substrate is increased to reduce stray capacitance, then the capacitance value decreases and photoelectric conversion efficiency improves, but the footprint of the through-wiring increases and pixel region cannot be sufficiently secured
Solution Approach 1:
The patent introduces a light shielding wall that extends in the vertical direction (thickness direction of substrate) to surround the through-wiring. This vertical dimension approach provides effective light shielding without requiring increased horizontal separation distance, thus reducing stray capacitance while maintaining compact footprint and securing pixel region.
Solution Approach 2:
The light shielding wall acts as an intermediary structure between the through-wiring and surrounding areas. It provides the necessary light shielding function while allowing the through-wiring to maintain a compact horizontal footprint, effectively mediating between the need for capacitance reduction and pixel region security.
2Measurement precision
If the distance of separation between the through-wiring and the semiconductor substrate is increased to reduce stray capacitance, then the capacitance value decreases and image signal quality improves, but the footprint of the through-wiring increases
Solution Approach 1:
The light shielding wall extends vertically to provide effective light shielding in the thickness direction, improving image signal quality by preventing optical interference without requiring increased horizontal separation distance. This maintains compact footprint while achieving the desired signal quality.
Solution Approach 2:
The light shielding wall serves as an intermediary that provides the necessary optical isolation for improved image signal quality while allowing the through-wiring to maintain a compact horizontal footprint, thus mediating between signal quality requirements and space constraints.
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 stray capacitance, enhances the efficiency of electric charge transfer, and improves the quality of image signals while allowing for a reduced footprint that secures the pixel region effectively.
Implementation Method 1
a stray capacitance (electrical capacitance) including the through-wiring, the insulating body, and the semiconductor substrate is added to the through-wiring
Implementation Method 2
a voltage supply circuit that supplies the electroconductive body with a voltage that causes a voltage difference between the first through-wiring and the electroconductive body to be small, when the electric charge is to be transferred to the first through-wiring
Implementation Method 3
a green-light photoelectric conversion region is disposed at one of surfaces of the semiconductor substrate, and includes an organic photoelectric conversion layer
Data Source
AI summary
A solid-state imaging device includes: a substrate including a first surface and a second surface that is opposed to the first surface; a first through-wiring that penetrates from the first surface of the substrate to the second surface of the substrate and through which electric charge is to be transferred; an electroconductive body formed in the substrate and along a periphery of a side surface of the first through-wiring with a dielectric body being interposed between the electroconductive body and the side surface; and a voltage supply circuit that supplies the electroconductive body with a voltage that causes a voltage difference between the first through-wiring and the electroconductive body to be small, when the electric charge is to be transferred to the first through-wiring.