Multi-probe ferromagnetic resonance (FMR) apparatus for wafer level characterization of magnetic films

Patent metadata

Field	Value
Publication number	US-11237240-B2
Application number	US-202017001476-A
Country	US
Kind code	B2
Filing date	Aug 24, 2020
Priority date	Aug 7, 2018
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

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.

First claim

What is claimed is:

1. A ferromagnetic resonance (FMR) measurement system comprising:
a plurality of RF probes, wherein each RF Probe is operable to transmit a RF input signal to one or more magnetic materials positioned at locations on a wafer;
a magnetic field source operable to provide a magnetic field proximate to each of the plurality of RF probes such that an application of the RF input signal at one or more microwave frequencies and the magnetic field induces a FMR condition in the one or more magnetic materials at each of the locations on the wafer;
one or more RF diodes operable to collect a RF output signal from one or more RF probes when the FMR condition occurs at each of the locations; and
a controller operable to receive an output signal from each RF diode, and wherein the output signal is indicative of one or more magnetic properties.

2. The FMR measurement system of claim 1 , further comprising a platform, wherein the plurality of RF probes are mounted on the platform to enable the plurality of RF probes to be positioned over all of the locations of the one or more magnetic materials.

3. The FMR measurement system of claim 1 , further comprising:
an RF generator that generates the RF input signal; and
a RF power distribution device coupled to the RF generator that delivers the RF input signal to all of the RF probes simultaneously.

4. The FMR measurement system of claim 1 , further comprising:
an RF generator that generates the RF input signal; and
a RF power distribution device coupled to the RF generator that delivers the RF input signal consecutively to each of the RF probes.

5. The FMR measurement system of claim 1 , wherein the magnetic field source includes a plurality of magnetic poles, and
wherein at least one magnetic pole is aligned above at least one of the RF probes, such that the magnetic field is applied in a direction that is orthogonal to the one or more magnetic materials at each of the locations on the wafer.

6. The FMR measurement system of claim 1 , wherein the magnetic field source includes a first magnetic pole and a second magnetic pole, and
wherein the first magnetic pole is positioned on a first side of one of the RF probe and the second magnetic pole is positioned on an opposing second side of the one of the RF probes such that the magnetic field is applied in an in-plane direction relative to the one or more magnetic materials that the RF probe is disposed thereover.

7. The FMR measurement system of claim 1 wherein the FMR condition is established by sweeping the magnetic field from a minimum value to a maximum value at the one or more microwave frequencies.

8. The FMR measurement system of claim 1 wherein the FMR condition is established by holding the magnetic field constant and sweeping with the one or more microwave frequencies.

9. A method comprising:
providing a wafer having one or more magnetic materials positioned at locations on the wafer;
providing a plurality of RF probes over the wafer, wherein each RF probe is disposed over at least one of the one or more magnetic materials positioned at locations on the wafer;
applying a magnetic field from a magnetic field source and applying one or more microwave frequencies from the plurality of RF probes to establish a FMR condition at each location of the one or more magnetic materials on the wafer;
receiving, by one or more RF diodes, a RF output signal from the one or more RF probes when the FMR condition occurs at each of the locations; and
receiving, by the controller, an output signal from each RF diode, and wherein the output signal is indicative of one or more magnetic properties.

10. The method of claim 9 , wherein receiving, by the controller, the output signal from each RF diode includes:
converting, by the one or more RF diodes, each RF output signal from the one or more RF probes to voltage signals; and
converting, by a data acquisition device, the voltage signal from each RF diode to a digitized output signal, and
sending the digitized output signal to the controller.

11. The method of claim 9 , wherein providing the plurality of RF probes over the wafer includes positioning at least one RF probe in physical contact with at least one of the one or more magnetic materials positioned at a location on the wafer.

12. The method of claim 9 , wherein the plurality of RF probes are spaced apart from all of the one of the one or more magnetic materials positioned at the locations on the wafer during the applying of the one or more microwave frequencies from the plurality of RF probes.

13. The method of claim 9 , wherein the applying of the magnetic field from the magnetic field source and the applying of the one or more microwave frequencies from the plurality of RF probes to establish the FMR condition at each location of the one or more magnetic materials on the wafer includes sweeping the magnetic field from a minimum value to a maximum value at the one or more microwave frequencies at each location of the one or more magnetic materials on the wafer.

14. The method of claim 9 , wherein the applying of the magnetic field from the magnetic field source and the applying of the one or more microwave frequencies from the plurality of RF probes to establish the FMR condition at each location of the one or more magnetic materials on the wafer includes holding the magnetic field constant and sweeping with the one or more microwave frequencies at each location of the one or more magnetic materials on the wafer.

15. The method of claim 9 , wherein the applying of the one or more microwave frequencies from the plurality of RF probes occurs simultaneously across all of the plurality of RF probes.

16. The method of claim 9 , wherein the applying of the one or more microwave frequencies from the plurality of RF probes includes applying the one or more microwave frequencies from a first RF probe from the plurality of RF probes at a first location of the one or more magnetic materials on the wafer and then applying the one or more microwave frequencies from a second RF probe from the plurality of RF probes at a second location of the one or more magnetic materials on the wafer after applying the one or more microwave frequencies from the first RF probe, the second location being different from the first location.

17. A ferromagnetic resonance (FMR) measurement system comprising:
a wafer table holding a wafer having one or more magnetic materials positioned at locations on the wafer;
a plurality of RF probes disposed over the wafer such that at least one RF probe is disposed over each of the locations having the one or more magnetic materials, wherein each RF Probe is operable to transmit a RF input signal to the one or more magnetic materials positioned at the locations on a wafer;
a magnetic field source operable to provide a magnetic field proximate to each of the plurality of RF probes such that an application of the RF input signal at one or more microwave frequencies and the magnetic field induces a FMR condition in the one or more magnetic materials at each of the locations on the wafer;
one or more RF diodes operable to obtain a RF output signal from one or more RF probes when the FMR condition occurs at each of the locations; and
a controller operable to receive an output signal from each RF diode, and wherein the output signal is indicative of one or more magnetic properties.

18. The FMR measurement system of claim 17 , wherein the applied one or more microwave frequencies range from about 0.01 GHz to about 100 GHz.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Guisan Santiago Serrano
• Thomas Luc
• Le Son
• Jan Guenole

Classifications

• G01R33/60 Primary

  using electron paramagnetic resonance (G01R33/24, G01R33/62 take precedence) · CPC title

• G01R33/345

  of waveguide type (G01R33/343 takes precedence) · CPC title

• G01N24/10 Primary

  by using electron paramagnetic resonance (G01N24/12 takes precedence) · CPC title

• G01R33/24

  for measuring direction or magnitude of magnetic fields or magnetic flux · CPC title