CMOS Image Sensor Shield Layer for Magnetic Noise Suppression
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Solution Overview
Problem
In solid-state imaging devices, the close proximity of pixel and logic circuits leads to magnetic field interference, causing eddy currents and noise in image quality due to the high-frequency and high-current operation of the logic circuit.
Innovation Solution
Incorporating a shield layer with high relative permeability, positioned below the first wiring, to shield the magnetic fields generated by the logic circuit's power supply lines, thereby reducing noise and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the logic circuit is positioned close to the pixel region to reduce device size, then the overall configuration size is reduced, but magnetic field interference occurs causing eddy currents and noise in image quality
Solution Approach 1:
A shield layer is introduced as an intermediary component between the logic circuit wiring and the pixel region wiring. This shield layer, positioned in a lower layer than both the first wiring (pixel region) and second wiring (logic circuit), acts as a mediator that blocks magnetic field interference from reaching the sensitive pixel signals, thereby resolving the contradiction between close proximity for size reduction and magnetic field interference prevention
2Productivity
If the logic circuit operates at high current and high frequency to enhance processing capability, then the processing speed is improved, but magnetic field generation increases causing eddy currents in pixel wirings
Solution Approach 1:
The shield layer is designed to utilize the magnetic field generated by the logic circuit in a beneficial way. By positioning the shield layer with high relative permeability material below the first wiring, the magnetic field lines are redirected through the shield layer rather than penetrating to the pixel region, converting the harmful magnetic field into a contained flux pattern that protects the pixel signals while allowing the logic circuit to operate at high current and frequency
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
The shield layer effectively reduces magnetic field interference, improving image quality by minimizing noise generation and enhancing the impedance of the grounding system, particularly for the first semiconductor substrate handling analog signals.
Implementation Method 1
a shield layer, wherein the second wiring is formed in a layer lower than that of the first wiring, and the shield layer is formed in a layer lower at least than that of the first wiring
Implementation Method 2
a magnetic field generated at a wiring (particularly, a power supply line) of the logic circuit is exerted on pixel wirings (particularly, signal lines) in the pixel region, whereby eddy currents would be generated
Data Source
AI summary
This technology relates to a solid-state imaging device and an electronic apparatus by which image quality can be enhanced. The solid-state imaging device includes a pixel region in which a plurality of pixels are arranged, a first wiring, a second wiring, and a shield layer. The second wiring is formed in a layer lower than that of the first wiring, and the shield layer is formed in a layer lower at least than that of the first wiring. This technology is applicable to a CMOS image sensor, for example.