Amorphous Magnetic Alloy for CMOS-Compatible On-Chip Inductors
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Solution Overview
Problem
Miniaturized power converters face challenges with high energy density magnetic materials, such as ferrite-based materials and metallic alloys, which are not compatible with CMOS chip processing temperatures and suffer from high AC losses due to low resistivity and eddy currents at high frequencies.
Innovation Solution
The development of an on-chip magnetic structure using a palladium-activated seed layer with a substantially amorphous magnetic material comprising nickel, iron, and phosphorous, and optionally boron, formed through electroless plating, which increases resistivity and reduces eddy currents, and is compatible with high-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ferrite-based materials are used for on-chip inductors, then thermal stability is improved, but processing temperature compatibility with CMOS is worsened due to high processing temperatures required
Solution Approach 1:
The patent changes the material composition parameters by incorporating specific elements (Co, Zr, Ta, B) in controlled amounts to create a magnetic alloy that maintains thermal stability at lower processing temperatures compatible with CMOS fabrication, eliminating the need for high-temperature ferrite processing
Solution Approach 2:
The patent creates a composite magnetic material system combining multiple elements (Co, Fe, Ni, Zr, Ta, B) with specific compositional ranges to achieve both thermal stability and CMOS compatibility, rather than using traditional ferrite or simple magnetic alloys
2Power
If magnetic alloys are used to achieve high energy density, then permeability and magnetic flux density are improved, but resistivity deteriorates leading to high AC losses at high frequencies
Solution Approach 1:
The patent optimizes the compositional parameters of the magnetic alloy, specifically controlling the content of Co (30-70 at.%), Fe (10-50 at.%), Ni (10-30 at.%), and adding Zr (0.1-5 at.%), Ta (0.1-5 at.%), and B (0.1-5 at.%) to simultaneously achieve high permeability, high resistivity, and high energy density
Solution Approach 2:
The patent develops a multi-element composite magnetic alloy that combines the advantages of different elements: Co and Fe provide high permeability and saturation magnetization, while Zr, Ta, and B increase resistivity to reduce eddy current losses, achieving both high energy density and low AC losses
3Adaptability or versatility
If conventional deposition methods are used for magnetic materials, then material variety is improved, but deposition rate and conformal coverage deteriorate
Solution Approach 1:
The patent replaces physical vapor deposition (PVD) methods with chemical deposition methods, specifically atomic layer deposition (ALD) and electroless plating, which provide significantly higher deposition rates and superior conformal coverage while maintaining the ability to deposit various magnetic materials
4Loss of energy
If magnetic layers are made thinner to reduce eddy currents, then eddy current losses are reduced, but magnetic flux density deteriorates
Solution Approach 1:
The patent changes the material properties by optimizing composition to achieve high resistivity (greater than 100 μΩ·cm) in thin magnetic layers, allowing the layers to be sufficiently thin to reduce eddy currents while maintaining adequate magnetic flux density through enhanced material performance
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 provides high resistivity and magnetic flux density, maintaining magnetic properties up to 250°C, reducing eddy currents, and enabling stable integration in miniaturized power converters.
Implementation Method 1
electrolessly plating a magnetic alloy onto the palladium-activated seed layer to form an amorphous soft magnetic layer
Implementation Method 2
large eddy currents can be induced within magnetic core. Eddy currents are circular electric currents induced within conductors by a changing magnetic field and result high AC losses at high frequencies. One method to reduce eddy currents is to increase the resistivity of the soft magnetic material
Data Source
AI summary
An on-chip magnetic structure includes a palladium activated seed layer and a substantially amorphous magnetic material disposed onto the palladium activated seed layer. The substantially amorphous magnetic material includes nickel in a range from about 50 to about 80 atomic % (at. %) based on the total number of atoms of the magnetic material, iron in a range from about 10 to about 50 at. % based on the total number of atoms of the magnetic material, and phosphorous in a range from about 0.1 to about 30 at. % based on the total number of atoms of the magnetic material. The magnetic material can include boron in a range from about 0.1 to about 5 at. % based on the total number of atoms of the magnetic material.