On-Chip Power Inductor with Segmented Permalloy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing on-chip power inductors face challenges in achieving high inductance and low resistance, leading to inefficiencies due to eddy current losses, particularly in DC-DC power supply systems, where traditional materials like aluminum and copper are used, and there is a need for improved integration schemes to meet increasing demand for high inductance values.
Innovation Solution
The use of patterned ferromagnetic or ferrimagnetic materials, such as Permalloy, with a conductive spiral coil and dielectric separation, along with optimized magnetic layer configurations and alignment techniques, to reduce eddy currents and enhance inductance, while integrating the inductor with transistor metallization for efficient power regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional interconnect metals (aluminum and copper) are used for on-chip inductors, then the inductor can be integrated on-chip, but the inductance value is insufficient and resistance is high
Solution Approach 1:
The patent uses a composite structure combining ferromagnetic material layers with conductive spiral coil layers. The ferromagnetic material (such as Permalloy) provides high permeability to enhance inductance, while the conductive metal layers (aluminum or copper) provide low-resistance current paths. This composite approach allows the inductor to achieve both high inductance and low resistance simultaneously, resolving the contradiction between inductance value and resistance loss.
2Quantity of substance
If solid magnetic plates are used to increase inductance, then inductance value increases, but eddy current losses increase reducing efficiency
Solution Approach 1:
The patent divides the magnetic plates into multiple segmented sections with gaps between them. This segmentation interrupts the continuous magnetic path, thereby reducing eddy current loops that cause energy losses. The gaps in the magnetic plates force eddy currents to take longer, more resistive paths, reducing their magnitude and associated losses while still maintaining sufficient magnetic flux for high inductance operation.
Solution Approach 2:
The patent applies different properties to different regions of the magnetic structure. The magnetic plates have high permeability regions (the solid portions) to concentrate magnetic flux and increase inductance, and low permeability regions (the gaps) to disrupt eddy current paths and reduce losses. This local differentiation of magnetic properties allows simultaneous optimization of both inductance and efficiency.
3Loss of energy
If thick and wide metal lines are used to reduce resistance, then resistance decreases, but the overall size of the inductor increases
Solution Approach 1:
The patent employs a composite structure where thick conductive metal layers (providing low resistance) are combined with high-permeability ferromagnetic material layers. The ferromagnetic material concentrates and guides magnetic flux through the spiral coil, enhancing inductance without requiring excessively wide metal traces. This allows the inductor to achieve low resistance through adequate metal thickness while maintaining compact overall dimensions through efficient magnetic flux confinement.
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 more efficient on-chip power inductor design with increased inductance and reduced resistance, minimizing eddy current losses and improving the overall performance and cost-effectiveness of DC-DC switching regulators.
Implementation Method 1
an on-chip power inductor structure that has advantages for power applications utilizing a high inductance, integrated, on-chip inductor structure
Implementation Method 2
According to Faraday's law, any change in the magnetic environment of a coil of wire will cause a voltage to be 'induced' in the coil
Implementation Method 3
If a metal plate is inserted into this empty space, then the induced electric field produces electric currents in the metal. These induced currents are called 'eddy currents.'
Implementation Method 4
The induced electric field is non-conservative: the work being done by the generated electric field cannot be recovered except as heat. That is, eddy currents create losses through Joule heating, thereby reducing the efficiency of many devices, e.g. inductors.
Data Source
AI summary
An on-chip inductor structure for a DC-DC power regulator circuit merges the switching transistor metallization with the inductor. Thick top level conductor metal that is used to strap the transistor array and to lower its on-state resistance is also used to extend the power inductor into the transistor array. Thus, the structure includes three basic components: a power inductor that spirals around the transistor array, the transistor array itself, and the transistor array metallization that is used to form a distributed inductance situated over the transistor array.