Multi-Probe FMR Wafer Characterization System
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Solution Overview
Problem
Conventional FMR techniques are destructive, time-consuming, and limited to measuring small pieces of wafers, making them unsuitable for wide acceptance in the magnetic data storage industry, as they cannot efficiently measure magnetic properties on whole wafers.
Innovation Solution
A fully automated FMR system with multiple RF probes and a magnetic assembly that applies a magnetic field to multiple sites on a wafer simultaneously, using a multi-port RF power distribution device to deliver microwave signals and detect FMR conditions at each site, allowing for simultaneous or consecutive measurements without moving the probe relative to the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FMR techniques are used to measure magnetic properties, then measurement precision is achieved, but measurement time is excessively long and only small pieces of wafers can be measured
Solution Approach 1:
The patent divides the wafer surface into multiple discrete measurement sites and uses multiple RF probes positioned at different locations to measure these sites simultaneously. This segmentation allows parallel measurement across the wafer surface, transforming a sequential single-point measurement process into a concurrent multi-point measurement system, thereby dramatically increasing throughput while maintaining measurement precision at each site
Solution Approach 2:
The patent combines multiple RF probes and magnetic field sources into a single integrated measurement system that operates simultaneously. By merging multiple measurement channels and coordinating their operation, the system achieves parallel data acquisition from multiple wafer locations, resolving the contradiction between maintaining precise measurements and increasing overall measurement productivity
2Productivity
If multiple sites on a wafer are measured simultaneously using multiple RF probes, then measurement time is reduced, but device complexity increases
Solution Approach 1:
The patent employs multiple RF probes that are identical in design and function, each capable of performing the same measurement task at different locations. This universality allows the system to handle multiple measurement sites with standardized components, reducing the complexity that would arise from using different specialized devices for each probe position
Solution Approach 2:
The patent introduces a control system and signal distribution network as intermediaries that coordinate the multiple RF probes and magnetic field sources. These intermediary components manage the complexity by providing centralized control, signal routing, and data aggregation, allowing the multiple probes to operate in coordination without requiring complex point-to-point connections and control logic
3Device complexity
If conventional single-probe FMR measurement is used, then device complexity is low, but measurement time per wafer is excessively long
Solution Approach 1:
The patent segments the measurement task into multiple parallel operations by positioning RF probes at different locations on the wafer. Instead of moving a single probe sequentially across the wafer surface, multiple probes simultaneously measure different sites, dividing the total measurement workload into concurrent operations that complete in parallel, thereby dramatically reducing measurement time
Solution Approach 2:
The patent positions multiple RF probes and magnetic field sources in advance at predetermined locations on the wafer before measurement begins. This preliminary arrangement of measurement points and equipment eliminates the need for sequential positioning and setup during the measurement process, allowing immediate simultaneous data acquisition from all sites and reducing overall measurement time
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 significantly reduces measurement time per wafer, enabling faster throughput and more accurate characterization of magnetic properties on whole wafers, improving the signal-to-noise ratio and making FMR a more viable characterization tool in the industry.
Implementation Method 1
a magnetic assembly with one or more magnetic field sources... a magnetic field is simultaneously applied vertically to each of 'm' predetermined locations
Implementation Method 2
When the ferromagnetic resonance condition is achieved, it may be detected by an enhanced absorption of the microwave (RF signal) by the ferromagnetic sample. The absorption is at a maximum at a specific frequency corresponding to the resonance frequency (fR) of the sample
Implementation Method 3
a multi-port RF power distribution device with a high level of isolation between output ports is used... capable of distributing and/or combining RF microwave signals
Data Source
AI summary
A ferromagnetic resonance (FMR) measurement system is disclosed with a plurality of “m” RF probes and one or more magnetic assemblies to enable a perpendicular-to-plane or in-plane magnetic field (Hap) to be applied simultaneously with a sequence of microwave frequencies (fR) at a plurality of “m” test locations on a magnetic film formed on a whole wafer under test (WUT). A FMR condition occurs in the magnetic film (stack of unpatterned layers or patterned structure) for each pair of (Hap, fR) values. RF input signals are distributed to the RF probes using RF power distribution or routing devices. RF output signals are transmitted through or reflected from the magnetic film to a plurality of “n” RF diodes where 1≤n≤m, and converted to voltage signals which a controller uses to determine effective anisotropy field, linewidth, damping coefficient, and/or inhomogeneous broadening at the predetermined test locations.