3D Stacked Image Sensor Layout for Lower Parasitic Capacitance
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Solution Overview
Problem
Three-dimensionally structured imaging devices are prone to influences from resistive, capacitive, and inductive components due to their complex internal circuit structures, leading to performance degradation.
Innovation Solution
The implementation of a low-permittivity region around specific circuits in a three-dimensionally structured imaging device, such as between wiring lines and semiconductor substrates, to reduce parasitic capacitance and improve signal processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a three-dimensionally structured imaging device is implemented with stacked substrates, then pixel density and integration are improved, but parasitic capacitance and signal degradation increase
Solution Approach 1:
The patent applies local quality by providing low-permittivity regions specifically around circuits that read electric charges from sensor pixels and output pixel signals, while other regions of the device maintain normal permittivity. This targeted approach reduces parasitic capacitance in critical areas without requiring changes to the entire device structure, thus resolving the contradiction between high pixel density and reduced parasitic capacitance.
Solution Approach 2:
The patent changes the permittivity parameter of the insulating material in specific regions by introducing low-permittivity materials or structures. This parameter change directly reduces the capacitive coupling between adjacent wiring lines and between wiring lines and substrates, thereby reducing parasitic capacitance while maintaining the three-dimensional stacked structure for high pixel density.
2Adaptability or versatility
If complex internal circuit structures are added to achieve higher integration, then device functionality is improved, but resistive, capacitive, and inductive component influences increase
Solution Approach 1:
The patent applies local quality by concentrating low-permittivity regions around specific circuits that are most susceptible to parasitic effects, particularly those reading electric charges from sensor pixels. This selective approach maintains complex circuit functionality while protecting critical signal paths from degradation due to resistive, capacitive, and inductive influences.
Solution Approach 2:
The low-permittivity regions act as intermediary elements between adjacent wiring lines and between wiring lines and substrates. These intermediary regions reduce the direct electromagnetic coupling that causes parasitic capacitance, thereby improving signal integrity while allowing complex circuit structures to maintain their functionality.
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 approach effectively minimizes the impact of parasitic capacitance, enhancing the conversion efficiency of electric charges into voltage and improving overall imaging device performance.
Implementation Method 1
a low-permittivity region is provided in at least any region around a circuit that reads electric charges from the sensor pixel and outputs the pixel signal
Implementation Method 2
reduce permittivity of a wiring line included in a second insulating layer or of a space around a second semiconductor substrate
Data Source
AI summary
An imaging device according to an embodiment of the present disclosure includes: a first substrate including a sensor pixel that performs photoelectric conversion; a second substrate including a pixel circuit that outputs a pixel signal on a basis of electric charges outputted from the sensor pixel; and a third substrate including a processing circuit that performs signal processing on the pixel signal. The first substrate, the second substrate, and the third substrate are stacked in this order, and a low-permittivity region is provided in at least any region around a circuit that reads electric charges from the sensor pixel and outputs the pixel signal.