Ferromagnetic Permeability Measurement via Impedance Strip
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Solution Overview
Problem
Existing methods for characterizing ferromagnetic materials in integrated circuits, particularly at high signal frequencies, are limited by the need for complex equipment like vibrating sample magnetometers that are not suitable for production environments and can only measure low frequencies.
Innovation Solution
A method using an impedance measurement instrument to determine the resistance of a ferromagnetic material strip at various frequencies, with numerical simulations to produce resistance versus frequency curves for selected permeability values, allowing for consistent permeability measurement in integrated circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vibrating sample magnetometer (VSM) is used to measure permeability of ferromagnetic materials, then measurement precision is improved, but device complexity and ease of operation worsen due to complex equipment requirements and limited applicability to high frequencies
Solution Approach 1:
The patent extracts the permeability measurement function from the complex VSM system and implements it using a simple impedance meter. The test strip is separated from the IC and measured independently using standard electrical measurement equipment, eliminating the need for complex magnetic field generation and vibration mechanisms while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical vibration system of the VSM with an electrical impedance measurement system. Instead of mechanically vibrating the sample in a magnetic field, the method uses electrical signals to excite the ferromagnetic material and measures the resulting impedance, substituting mechanical operations with electrical measurements that are easier to implement in production environments.
2Measurement precision
If a vibrating sample magnetometer (VSM) is used for permeability measurement, then measurement precision is improved, but productivity worsens due to operation limited to very low frequencies
Solution Approach 1:
The patent changes the measurement parameter from mechanical vibration frequency (limited to <100 Hz) to electrical signal frequency (up to 100 MHz). By using impedance measurement with varying frequency electrical signals, the method enables permeability characterization across the full RF frequency range required for IC applications, dramatically improving productivity and applicability.
3Ease of operation
If ferromagnetic material is tested within the IC environment, then ease of operation is improved, but measurement precision worsens due to interference from surrounding circuitry
Solution Approach 1:
The patent segments the ferromagnetic material into a separate test strip that is physically isolated from the IC circuitry. This test strip can be measured independently using simple impedance equipment, eliminating interference from surrounding conductors and semiconductor devices while maintaining ease of operation in production environments.
Solution Approach 2:
The patent introduces an intermediary measurement approach using impedance meters that can interface with standard test fixtures. The test strip serves as an intermediary element that bridges the gap between the ferromagnetic material and the measurement equipment, enabling accurate measurements without direct integration complexity.
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
Enables accurate and efficient measurement of permeability in ferromagnetic materials within integrated circuits at high signal frequencies, suitable for production environments, by isolating the test strip and using simulations to estimate permeability based on impedance changes.
Implementation Method 1
measuring an impedance of the strip of the ferromagnetic material with the impedance measurement instrument at each of a plurality of measurement signal frequencies
Implementation Method 2
a width substantially wider than the critical dimension; electrically coupling an impedance measurement instrument to the first and second measurement contacts
Implementation Method 3
determining consistency of a permeability of a ferromagnetic material used in integrated circuits
Data Source
AI summary
A method for determining consistency of a permeability of a ferromagnetic material in integrated circuits in which a test strip of the subject ferromagnetic material is included for testing with an impedance measurement instrument, such as an inductance-capacitance-resistance (LCR) meter, with which the resistance of the strip of ferromagnetic material over a range of measurement signal frequencies is determined based upon the measured impedance values. The measured impedance values, measurement signal frequencies and selected permeability values are then used in numerical simulations to produce multiple resistance versus frequency curves each of which corresponds to one of the selected permeability values.