Magnetic Coil Isolator Structure for Higher Breakdown Voltage
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Solution Overview
Problem
Existing isolators for power control are expensive and face challenges in manufacturing processes that lead to electrical shorting and reduced breakdown voltage due to nonuniform etching and polishing, which affect yield and efficiency.
Innovation Solution
The isolator design includes specific insulating film configurations and manufacturing methods using silicon nitride and silicon oxide films to control etching rates, reducing electrical shorting risks and increasing breakdown voltage by optimizing coil and interconnect structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing processes are used, then production cost is reduced, but manufacturing precision deteriorates due to nonuniform etching and polishing causing electrical shorting
Solution Approach 1:
The patent changes the material parameter by using silicon nitride film instead of conventional insulating materials. This material parameter change fundamentally alters the etching behavior, enabling uniform etching rates across the substrate surface and eliminating the nonuniformity that causes electrical shorting in conventional processes.
Solution Approach 2:
The patent employs a composite structure combining silicon nitride film with silicon oxide film. The silicon nitride layer provides uniform etching characteristics, while the silicon oxide layer offers appropriate dielectric properties. This composite material approach resolves the contradiction by leveraging the complementary advantages of different materials.
2Reliability
If conventional insulating film structures are used, then device complexity is reduced, but reliability deteriorates due to reduced breakdown voltage
Solution Approach 1:
The patent changes the dielectric parameter by introducing silicon nitride film with superior breakdown characteristics. This material substitution directly increases the breakdown voltage, enhancing reliability. The associated increase in device complexity is acceptable given the critical importance of reliability in power control applications.
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 design enhances manufacturing yield and breakdown voltage while maintaining magnetic coupling efficiency, addressing the cost and performance issues of traditional isolators.
Implementation Method 1
a first coil extending in the second insulating film and the first insulating film, the first coil having a length in the first direction from the front surface of the second insulating film into the first insulating film, the length in the first direction of the first coil being greater than the thickness in the first direction of the first interconnect; a second coil provided at the front side of the third insulating film, the second coil facing the first coil via the third insulating film
Data Source
AI summary
An isolator includes a substrate; a first insulating film on the substrate; a second insulating film on the first insulating film, a third insulating film on the second insulating film, a first interconnect in the second insulating film, and first and second coils. The first interconnect has a thickness equal to a film thickness of the second insulating film. The first coil extends in the first and second insulating films. The first coil has a length in the extending direction greater than the thickness of the first interconnect. The third insulating film is provided on the second insulating film, and covers the first interconnect and the first coil. The second coil is provided on the third insulating film, and faces the first coil via the third insulating film.