3D Compact Coils for Low-Frequency Filter Miniaturization
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Solution Overview
Problem
Existing electrical components, such as inductors and filters, are large in size, particularly for low-frequency applications like GSM in mobile devices, and lack magnetic coupling, limiting their miniaturization and integration in semiconductor devices.
Innovation Solution
The development of compact coil structures with heights greater than the skin current depth, which are magnetically coupled and integrated with capacitors on a substrate, allowing for a series of coil structures to form spiral inductors and achieve a more compact design compatible with semiconductor technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional lumped LC networks or distributed-line resonators are used for filter design, then filtering functionality is achieved, but the component size becomes large particularly for low-frequency applications
Solution Approach 1:
The patent transitions from planar 2D coil structures to three-dimensional 3D coil structures with vertical stacking. The 3D coils utilize the vertical dimension by forming multiple turns that extend in the z-direction, enabling magnetic coupling between adjacent coils while reducing the horizontal footprint. This dimensional transition allows compact filter design for low-frequency applications without sacrificing filtering performance
Solution Approach 2:
The patent implements nested coil structures where inner coils are positioned within the geometric bounds of outer coils. The 3D coils are formed with multiple turns that are nested concentrically, with each turn positioned at different radial distances from the center. This nesting arrangement maximizes the use of available space and enables magnetic coupling while minimizing the overall component footprint
2Reliability
If inductor components are made larger to achieve low-frequency operation, then filtering performance improves, but device miniaturization is limited
Solution Approach 1:
The patent employs 3D coil structures that extend vertically to achieve the necessary inductance values for low-frequency operation. By utilizing the vertical dimension, the coils can maintain adequate inductance without requiring large horizontal footprints. The 3D configuration allows the magnetic field to be concentrated in a compact volume, enabling low-frequency filtering performance in a miniaturized component
Solution Approach 2:
The patent uses composite structures combining conductive coil materials with magnetic core materials or magnetic shielding layers. The 3D coils may be formed with ferromagnetic materials or placed near magnetic shields to enhance the magnetic coupling efficiency. This composite approach increases the effective permeability, allowing smaller coil dimensions to achieve the required inductance for low-frequency applications
3Ease of manufacture
If traditional non-magnetically coupled inductors are used, then manufacturing is simpler, but device footprint and interconnection requirements increase
Solution Approach 1:
The patent merges multiple inductor functions into a single integrated 3D coil structure. The 3D coils are formed as monolithic structures using semiconductor fabrication processes, where multiple turns are created in a single continuous conductive layer. This merging eliminates the need for separate inductor components and their associated interconnections, reducing device footprint while maintaining manufacturing simplicity through standard semiconductor processing
Solution Approach 2:
The transition to 3D coil structures enables magnetic coupling to be achieved within a compact volume by utilizing vertical stacking. The 3D coils are positioned adjacent to each other in the vertical direction, allowing magnetic coupling without requiring large horizontal spacing. This dimensional approach reduces the overall device footprint while maintaining ease of manufacture through conformal deposition processes
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 results in a significant reduction in size, weight, and interconnections, enabling high-performance filtering and diplexing functionality in smaller devices while maintaining efficiency and cost-effectiveness.
Implementation Method 1
The first, second, and third coil structures each have a height greater than a skin current depth of the coil structure defined as a depth which current reduces to 1/(complex permittivity) of a surface current value
Implementation Method 2
The first and second coil structures each have a height greater than a skin current depth of the coil structure. A first end of the first coil structure is placed 90 degrees from a first end of the second coil structure
Data Source
AI summary
A semiconductor device has a first coil structure formed over the substrate. A second coil structure is formed over the substrate adjacent to the first coil structure. A third coil structure is formed over the substrate adjacent to the second coil structure. The first and second coil structures are coupled by mutual inductance, and the second and third coil structures are coupled by mutual inductance. The first, second, and third coil structures each have a height greater than a skin current depth of the coil structure defined as a depth which current reduces to 1/(complex permittivity) of a surface current value. In the case of copper, the coil structures have a height greater than 5 micrometers.The first, second, and third coil structures are arranged in rounded or polygonal pattern horizontally across the substrate with a substantially flat vertical profile.