Monolithic Semiconductor Common Mode Filter with ESD Protection
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Solution Overview
Problem
In high-speed data transmission systems, existing semiconductor components face challenges in providing noise immunity and protection from large transient voltage and current spikes due to the large area occupation of noise filters and ESD protection circuits on PCBs, which is undesirable in mobile devices, and manufacturing filter elements on low resistivity substrates degrades performance.
Innovation Solution
A semiconductor component with a common mode filter monolithically integrated with an ESD protection device using a high resistivity substrate, where the resistivity of a portion is decreased to manufacture ESD protection devices, and coils of the common mode filter are integrated at different vertical levels using thick polyimide layers to reduce capacitance and eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If noise filters and ESD protection circuits are mounted on PCB, then noise immunity and transient protection are improved, but area occupation increases
Solution Approach 1:
The patent combines the common mode filter and ESD protection circuit into a single monolithic semiconductor component fabricated on one substrate. The filter inductors and ESD protection devices share the same substrate and are interconnected through integrated conductive structures, eliminating the need for separate discrete components and reducing overall PCB area while maintaining both noise filtering and ESD protection functions.
2Ease of manufacture
If filter elements are manufactured on low resistivity substrate, then manufacturing is simplified, but filter performance degrades due to eddy currents
Solution Approach 1:
The patent applies different substrate resistivity characteristics to different functional regions: the common mode filter inductors are fabricated on a high resistivity substrate region to minimize eddy currents and maintain filter performance, while the ESD protection circuit is fabricated on a low resistivity substrate region to handle high ESD currents effectively. This local differentiation allows each component to operate optimally without compromising the other.
3Area of stationary object
If coils are integrated at different vertical levels, then area is reduced, but capacitance and eddy currents increase
Solution Approach 1:
The patent introduces thick polyimide layers as intermediary insulating structures between the coils at different vertical levels. These polyimide layers serve as both electrical insulators and magnetic shielding, preventing eddy currents in the substrate while maintaining the compact vertical integration. The polyimide material specifically addresses high frequency losses by providing electrical isolation without conducting eddy currents.
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 solution effectively reduces the area occupied by the components, enhances noise filtering and ESD protection, and maintains performance by minimizing high frequency losses and eddy currents, while meeting mobile device standards for drop tests and temperature cycles.
Implementation Method 1
thick polyimide layers to reduce capacitance and eddy currents
Data Source
AI summary
A common mode filter monolithically integrated with a protection device. In accordance with an embodiment a semiconductor material having a resistivity of at least 5 Ohm-centimeters is provided. A protection device is formed from a portion of the semiconductor material and a dielectric material is formed over the semiconductor material. A coil is formed over the dielectric material.