Inductor Innermost Turn Width Optimization for Eddy Current Reduction
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Solution Overview
Problem
Inductor structures in integrated circuits face challenges due to conductor thickness limitations and silicon substrate interference, leading to unsatisfactory inductor quality, particularly exacerbated by eddy currents at the inner turns, which degrade the Q value and hinder efficient energy storage and release.
Innovation Solution
The inductor structure features an innermost coil turn with a narrower width at regions of higher magnetic flux density, reducing eddy currents and parasitic capacitance, while maintaining the flow path of induction current, thereby improving inductor quality and Q value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick metal is disposed on the top layer of the inductor to reduce conductor loss, then the Q value of the inductor is improved, but the eddy current impact is exacerbated and the uniformity of current in the inner turn is poor
Solution Approach 1:
The patent applies local quality by making the innermost coil turn have a different width at different positions. Specifically, the innermost coil turn has a narrower width at the inner side compared to the outer side, creating non-uniform current distribution that compensates for the eddy current effects. This local geometric modification allows the thick metal layer to reduce overall conductor loss while the narrowed inner region mitigates the harmful eddy current concentration at the inner turn bends.
2Ease of manufacture
If the thickness of the inductor conductor is limited in IC processes, then the manufacturing is feasible, but the inductor quality is unsatisfactory due to increased resistance
Solution Approach 1:
The patent changes the geometric parameters of the coil turns, specifically the width of the innermost coil turn. By narrowing the width at the inner side of the innermost turn, the effective conductor cross-section is optimized to reduce resistance effects. This parameter modification allows the inductor to achieve better quality factor despite the constraints on conductor thickness in IC manufacturing processes.
3Quantity of substance
If the cross-sectional area of the conductor is fully used, then the current capacity is maximized, but the eddy current prevents uniform current distribution in the inner turn
Solution Approach 1:
The patent introduces asymmetry in the innermost coil turn by making its width non-uniform along its length. The inner side of the innermost turn has a narrower width compared to the outer side. This asymmetric geometry deliberately creates non-uniform current distribution that counteracts the eddy current effects, achieving more stable and uniform effective current flow through the conductor cross-section despite the presence of eddy currents.
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 design effectively reduces eddy currents and parasitic capacitance, enhancing the inductor's quality factor and overall performance by optimizing the innermost coil turn geometry.
Implementation Method 1
inductors can store/release energy under the condition of electromagnetic conversion
Implementation Method 2
the inductor structure with a thick metal disposed on the top layer thereof is still affected by an eddy current
Data Source
AI summary
An inductor structure disposed over a substrate and including a coil layer is provided. The coil layer has a plurality of coil turns electrically connected with each other. An innermost coil turn of the coil layer has a portion with a narrower width in a region with a higher magnetic flux density than that in the other region with lower magnetic flux density.