Slow Wave Inductive Structure With 3D Stacked Windings
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Solution Overview
Problem
As technology nodes shrink, inductors and transformers occupy a large area in circuits, leading to increased proximity with other devices, higher resistance in metal lines, reduced quality factor, and magnetic flux-induced noise, which complicates current regulation and efficiency.
Innovation Solution
A slow wave inductive structure is designed with a second substrate that reduces current propagation speed, increasing inductance without enlarging the conductive windings, and includes adjustable switches to control inductance and quality factor, utilizing multi-layer dielectric materials and conductive vias to connect windings across substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductors and transformers are designed with larger conductive windings to maintain inductance, then inductance strength is improved, but circuit area increases and proximity to other devices increases
Solution Approach 1:
The patent transitions from planar 2D winding structures to 3D vertical stacking with multiple substrates separated by dielectric layers. Conductive windings are distributed across different spatial planes and connected via vertical vias, enabling inductance accumulation in the vertical dimension rather than requiring expanded horizontal area.
Solution Approach 2:
The patent employs composite structures combining conductive winding materials, dielectric materials between substrates, and metallic via materials. This composite approach enables optimized electromagnetic performance with compact footprint by leveraging the complementary properties of different materials in a multi-layer configuration.
2Area of stationary object
If metal line size is reduced to shrink circuit, then circuit area decreases, but resistance in metal lines increases
Solution Approach 1:
The patent compensates for reduced metal line cross-section by extending the current path through the vertical dimension. Multiple winding turns across stacked substrates connected by vias create longer effective conductor length, maintaining inductance and reducing resistance impacts despite smaller lateral dimensions.
Solution Approach 2:
The patent introduces adjustable switches that can dynamically reconfigure current paths through the winding structure. This enables optimization of current distribution to minimize resistance losses under different operating conditions while maintaining compact geometry.
3Area of stationary object
If conductive windings are placed closer together to reduce area, then circuit area decreases, but magnetic flux interference between windings increases
Solution Approach 1:
The patent separates adjacent conductive windings into different vertical planes using dielectric substrates. This spatial separation in the vertical dimension reduces magnetic coupling and flux interference between windings while maintaining compact horizontal footprint.
Solution Approach 2:
The patent introduces dielectric materials as intermediary layers between conductive windings on different substrates. These dielectric layers provide electrical isolation and reduce parasitic magnetic coupling, acting as mediators that enable close proximity placement while minimizing harmful flux interactions.
4Reliability
If inductors and transformers occupy larger area, then inductance can be maintained, but quality factor decreases due to increased resistance
Solution Approach 1:
The patent achieves high inductance values through vertical stacking of multiple winding layers on separate substrates. This 3D configuration concentrates magnetic flux in the vertical dimension, achieving high inductance with minimal horizontal area and reduced resistive losses from shorter lateral current paths.
Solution Approach 2:
The patent incorporates adjustable switches that enable dynamic optimization of the Q-factor by reconfiguring current paths. Under different operating conditions, the switches can select optimal winding combinations to maximize quality factor while maintaining required inductance values.
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 allows for a smaller circuit size with maintained inductance strength, reduced noise interference, and adjustable inductance and quality factor, enhancing the efficiency and compactness of circuit designs.
Implementation Method 1
A slow wave inductive structure is designed with a second substrate that reduces current propagation speed, increasing inductance without enlarging the conductive windings
Implementation Method 2
When a current flows through the inductor, energy is stored temporarily in a magnetic field in the inductor
Data Source
AI summary
A method of making a slow wave inductive structure includes depositing a first dielectric layer over a first substrate. The method further includes forming a first conductive winding in the first dielectric layer. The method further includes bonding a second substrate to the first dielectric layer, wherein the second substrate is physically separated from the first conductive winding, and the second substrate has a thickness ranging from about 50 nanometers (nm) to about 150 nm. The method further includes depositing a second dielectric layer over the second substrate. The method further includes forming a second conductive winding in the second dielectric layer, wherein the second substrate is physically separated from the second conductive winding.