3D Stacked Inductor With Magnetic Shielding Layers
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Solution Overview
Problem
Conventional inductors require significant space and are often distant from the die in integrated circuits, leading to larger form factors that are unsuitable for mobile and wearable computing devices, and their integration into substrates can reduce inductance due to interactions with nearby metal layers.
Innovation Solution
A three-dimensional inductor apparatus with a first and second metal layer, dielectric layer, and magnetic layers that constrain and guide magnetic fields, increasing inductance density while allowing for compact designs by positioning magnetic layers between and outside the inductor loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional inductor designs are used, then inductance can be achieved, but the device requires significant space and creates a larger form factor
Solution Approach 1:
The patent transitions from planar inductor designs to three-dimensional stacked inductor structures. Multiple inductor loops are arranged in different vertical layers (first inductor loop in a first plane, second inductor loop in a second plane), utilizing the Z-dimension to increase inductance density without proportionally increasing the footprint area. This dimensional transition allows achieving higher inductance values within compact form factors suitable for mobile devices.
Solution Approach 2:
The patent implements nested inductor structures where inner inductor loops are positioned within the boundaries of outer inductor loops. The first inductor loop includes an inner portion and an outer portion, with the second inductor loop nested within the inner portion. This nesting arrangement maximizes the use of available space and increases the effective inductance density by utilizing overlapping magnetic field regions.
2Area of stationary object
If inductors are placed close to the die, then routing space is reduced, but magnetic field interactions with nearby metal layers increase causing inductance reduction
Solution Approach 1:
The patent introduces magnetic shielding layers (first magnetic shielding layer and second magnetic shielding layer) as intermediary elements between the inductor loops and surrounding metal layers. These shielding layers, made of magnetic material, act as mediators that guide and contain the magnetic fields generated by the inductors, preventing unwanted magnetic field interactions with adjacent metal layers and ground planes. This allows the inductor to be positioned close to the die while maintaining effective inductance.
Solution Approach 2:
The patent applies magnetic shielding selectively in specific regions where magnetic field interactions are problematic. The first magnetic shielding layer is positioned between the first inductor loop and the first metal layer, while the second magnetic shielding layer is positioned between the second inductor loop and the second metal layer. This localized application of magnetic shielding material optimizes the magnetic field distribution precisely where needed, maintaining inductance while enabling compact integration.
3Reliability
If magnetic shielding layers are added to maintain inductance, then inductance density is preserved, but device complexity increases
Solution Approach 1:
The magnetic shielding layers serve multiple functions simultaneously: they act as magnetic field guides to maintain inductance, provide electromagnetic interference (EMI) shielding, and can be integrated with existing substrate layers. The shielding layers are formed using standard semiconductor fabrication processes (sputtering or evaporation of magnetic material), making them compatible with existing manufacturing workflows. This multi-functionality reduces the overall system complexity despite adding structural elements.
Solution Approach 2:
The patent combines the magnetic shielding function with the existing multi-layer substrate structure. The first and second magnetic shielding layers are integrated into the stack of metal layers and dielectric layers, merging the shielding function with the interconnect structure. The inductor loops, shielding layers, and substrate layers are combined into a single integrated three-dimensional structure, reducing the need for separate shielding components and simplifying the overall device architecture.
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 enables a compact inductor design that can be placed close to the die, maintaining high inductance density and reducing energy loss from eddy currents, thus facilitating smaller device form factors without compromising performance.
Implementation Method 1
magnetic layers that constrain and guide magnetic fields, increasing inductance density
Implementation Method 2
The inductor loops generate a magnetic field when current is applied through the embedded inductor
Implementation Method 3
The magnetic field surrounding the embedded inductor can interact with the nearby first metal layer and fourth metal layer, such that the effective inductance of the embedded inductor is greatly reduced
Data Source
AI summary
Some aspects pertain to an inductor apparatus that includes a first metal layer including a plurality of first interconnects, a second metal including a plurality of second interconnects, a first dielectric layer between the first metal layer and the second metal layer, and an inductor. The inductor includes a plurality of vias, where the plurality of vias are configured to couple the plurality of first interconnects to the plurality of second interconnects. The inductor includes a plurality of inductor loops formed by the plurality of vias, the plurality of first interconnects and the plurality of second interconnects. The inductor further includes a first magnetic layer and a second magnetic layer, located between the first interconnects and the second interconnects; and a third magnetic layer and an optional fourth magnetic layer outside of the plurality of inductor loops.