Vertical Laminated Magnetic Core for High-Inductance CMOS Inductors
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Solution Overview
Problem
Current technologies lack practical inductors with high inductance, low resistance, high current rating, and high frequency response, which are necessary for efficient switched-inductor power conversion in compact and dense semiconductor devices, particularly for CMOS integration, where energy efficiency and low inductor current ripple are critical.
Innovation Solution
A method for manufacturing a vertically-laminated ferromagnetic core involving the deposition of a conductive seed layer, masking layer, and ferromagnetic material on a substrate, with patterned voids and a conductive coil around the core to achieve high aspect ratio ferromagnetic layers, enhancing inductance and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional planar inductor structures are used, then manufacturing is simpler, but inductance and energy efficiency are insufficient for high-current power conversion
Solution Approach 1:
The patent transitions from conventional planar (2D) inductor structures to vertically-laminated (3D) ferromagnetic core structures. This dimensional change enables significantly higher inductance values and energy efficiency by utilizing vertical stacking of ferromagnetic layers with conductive windings, allowing magnetic flux to pass through multiple laminated layers in the vertical direction, thereby resolving the energy efficiency limitation of planar structures.
Solution Approach 2:
The patent employs composite structures combining ferromagnetic materials (such as nickel-iron alloys) with conductive windings in a vertically-laminated configuration. This composite approach integrates the high permeability of ferromagnetic materials with the electrical conductivity of wire windings, creating an inductor that achieves both high inductance and low resistance, thus improving energy efficiency without excessive complexity.
2Volume of moving object
If inductor size is reduced for CMOS integration, then device density increases, but achieving high inductance and low resistance becomes impractical
Solution Approach 1:
The vertically-laminated structure exploits the third dimension (vertical stacking) to achieve high inductance within a small planar footprint. By stacking multiple thin ferromagnetic layers with conductive windings between them, the inductor achieves high inductance values (greater than 1 nH) and low resistance (less than 1 ohm) while occupying less than 1 mm² area, enabling CMOS integration without sacrificing performance.
Solution Approach 2:
The inductor is segmented into multiple thin ferromagnetic layers stacked vertically, with conductive windings positioned between the layers. This segmentation allows the magnetic path to extend through multiple layers, increasing effective inductance, while each individual layer remains thin enough to maintain low resistance and fit within the small area required for CMOS integration.
3Reliability
If high permeability ferromagnetic material is used, then inductance increases, but manufacturing complexity and integration difficulty increase
Solution Approach 1:
The vertically-laminated structure uses thin ferromagnetic layers deposited in the vertical direction through sequential deposition processes. This approach enables the use of high permeability materials (such as nickel-iron alloys with permeability greater than 100) while maintaining compatibility with standard semiconductor manufacturing techniques, as each layer can be deposited using conventional thin-film deposition methods followed by patterning and etching.
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 the creation of inductors with improved energy efficiency and reduced power loss, suitable for high-density CMOS integration, supporting advanced power conversion and dynamic voltage scaling.
Implementation Method 1
A conductive coil is disposed around the vertically-laminated ferromagnetic core
Implementation Method 2
Use of high permeability, low coercivity material is typically required to achieve the desired inductor properties
Data Source
AI summary
A method for manufacturing a vertically-laminated ferromagnetic core includes (a) depositing a conductive seed layer on or over a first side of a substrate; (b) depositing a masking layer on or over a second side of the substrate, the first and second sides on opposite sides of the substrate; (c) forming a pattern in the masking layer; (d) dry etching the substrate, based on the pattern in the masking layer, from the second side to the first side to expose portions of the conductive seed layer; and (e) depositing a ferromagnetic material onto the exposed portions of the conductive seed layer to form vertically-oriented ferromagnetic layers.