Isolation Capacitor Shielding for Dielectric Breakdown
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Solution Overview
Problem
Galvanic isolation capacitor systems face limitations in isolation capability due to dielectric breakdown near the capacitor plates, which occurs when the peak electric field exceeds the dielectric strength of the surrounding dielectric, particularly in high voltage domains.
Innovation Solution
A multilevel metallization structure with a capacitor and a conductive shield is implemented, where the capacitor terminals overlap by 1.0 μm to 6.0 μm and the conductive shield encircles the capacitor with metal lines and vias, providing a Faraday cage effect to reduce electric field stress and enhance dielectric strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacitor plates are placed close together to increase capacitance, then the capacitance value increases, but the peak electric field increases causing dielectric breakdown
Solution Approach 1:
A conductive shield (Faraday cage) is introduced as an intermediary structure between the capacitor plates and the surrounding dielectric. This shield redistributes the electric field lines, preventing concentration at the plate edges and reducing the peak electric field strength in the surrounding dielectric, thereby preventing dielectric breakdown while maintaining high capacitance
Solution Approach 2:
The invention changes the electric field distribution parameter by introducing the conductive shield. The shield modifies the field geometry, transforming the concentrated edge-field into a more distributed pattern, which reduces the peak field intensity without changing the capacitor plate geometry or dielectric material properties
2Reliability
If a conductive shield is added to reduce electric field stress, then dielectric breakdown risk decreases, but device complexity increases
Solution Approach 1:
The conductive shield is integrated into the existing multilevel metallization structure, serving both as part of the standard interconnect architecture and as a Faraday cage for electric field management. This multi-functionality approach reduces the need for separate shielding structures, thereby limiting the increase in device complexity
Solution Approach 2:
The shielding function is merged with the existing metallization layers and capacitor structure. The conductive shield utilizes the same fabrication processes and material layers as the standard interconnect structure, combining multiple functions (interconnection and shielding) into a unified design that minimizes additional complexity
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 significantly reduces the risk of dielectric breakdown, enhancing the isolation capability and increasing the bipolar surge capacity of the electronic device beyond standard specifications, thereby improving device reliability and safety.
Implementation Method 1
the conductive shield encircles the capacitor with metal lines and vias, providing a Faraday cage effect to reduce electric field stress and enhance dielectric strength
Implementation Method 2
High voltage digital isolators provide communication channels between different voltage domains... In galvanic isolation capacitor systems
Data Source
AI summary
An electronic device has a conductive shield between first and second regions in a multilevel metallization structure, as well as a capacitor with first and second terminals in the first region, the first terminal laterally overlaps the second terminal by an overlap distance of 1.0 μm to 6.0 μm, the conductive shield includes a first metal line that encircles the first terminal, and the first metal line is spaced apart from the first terminal by a gap distance of 0.5 μm to 1.0 μm.