Magnetic sensor array with single TMR film plus laser annealing and characterization

Patent metadata

Field	Value
Publication number	US-11495252-B2
Application number	US-202117448166-A
Country	US
Kind code	B2
Filing date	Sep 20, 2021
Priority date	Dec 27, 2019
Publication date	Nov 8, 2022
Grant date	Nov 8, 2022

Abstract

The present disclosure generally relates to a Wheatstone bridge array that has four resistors. Each resistor includes a plurality of TMR films. Each resistor has identical TMR films. The TMR films of two resistors have reference layers that have an antiparallel magnetic orientation relative to the TMR films of the other two resistors. To ensure the antiparallel magnetic orientation, the TMR films are all formed simultaneously and annealed in a magnetic field simultaneously. Thereafter, the TMR films of two resistors are annealed a second time in a magnetic field while the TMR films of the other two resistors are not annealed a second time.

First claim

What is claimed is:

1. A method of manufacturing a TMR sensor device, comprising:
forming a first tunnel magnetoresistive (TMR) film on a substrate;
forming a second TMR film on the substrate;
annealing the first TMR film and the second TMR film in a magnetic field; and
annealing the second TMR film a second time in a magnetic field,
wherein the TMR sensor device comprises:
a first resistor comprising at least one first TMR film having a first reference layer and a first pinned layer; and
a second resistor electrically coupled to the first resistor comprising at least one second TMR film having a second reference layer and a second pinned layer, wherein:
the first reference layer and the second reference layer have an antiparallel magnetic orientation,
the first pinned layer and the second pinned layer have a parallel magnetic orientation, and
the magnetic orientation of the second pinned layer is parallel to the magnetic orientation of the second reference layer.

2. The method of claim 1 , wherein during the annealing of the second TMR film a second time, the first TMR film is not annealed.

3. The method of claim 1 , wherein the magnetic field for the annealing the second TMR film a second time is less than the magnetic field for the annealing the first TMR film and the second TMR film.

4. The method of claim 1 , wherein the annealing the second TMR film a second time is performed by laser annealing in a magnetic field.

5. The method of claim 4 , wherein the laser annealing occurs with a laser beam size of less than 1 mm.

6. The method of claim 1 , wherein during the annealing the second TMR film a second time in a magnetic field, the first TMR film is not masked.

7. The method of claim 1 , wherein the first resistor further comprises a first spacer layer, the first spacer layer sandwiched by and contacting both the first reference layer and the first pinned layer, wherein the second resistor further comprises a second spacer layer, the second spacer layer sandwiched by and contacting both the second reference layer and the second pinned layer, and wherein the first TMR film and the second TMR film are substantially identical.

8. The method of claim 7 , the TMR sensor device further comprising:
a third resistor comprising at least one third TMR film having a third reference layer; and
a fourth resistor comprising at least one fourth TMR film having a fourth reference layer.

9. The method of claim 8 , wherein the third TMR film and the fourth TMR film are substantially identical, and wherein the third reference layer and the fourth reference layer have an antiparallel magnetic orientation.

10. The method of claim 9 , wherein the first TMR film, the second TMR film, the third TMR film, and the fourth TMR film are substantially identical.

11. The method of claim 10 , wherein the first reference layer and the third reference layer have a parallel magnetic orientation, and wherein the second reference layer and the fourth reference layer have a parallel magnetic orientation.

12. The method of claim 7 , wherein the first TMR film and the second TMR film each comprise:
a seed layer;
an antiferromagnetic layer disposed on the seed layer;
a pinned layer disposed on the antiferromagnetic layer, wherein the pinned layer is either the first pinned layer or the second pinned layer;
a spacer layer disposed on the pinned layer, wherein the spacer layer is either the first spacer layer or the second spacer layer;
a reference layer disposed on the spacer layer, wherein the reference layer is either the first reference layer or the second reference layer;
a barrier layer disposed on the reference layer; and
a free layer disposed on the barrier layer.

13. The method of claim 7 , wherein the first TMR film has an R-H curve that has a positive slope and the second TMR film has an R-H curve that has a negative slope.

14. The method of claim 7 , wherein the first resistor and the second resistor have the same resistance area (RA).

15. A method of manufacturing a TMR sensor device, comprising:
forming a first tunnel magnetoresistive (TMR) film on a substrate;
forming a second TMR film on the substrate;
annealing the first TMR film and the second TMR film in a magnetic field; and
annealing the second TMR film a second time in a magnetic field, wherein the TMR sensor device comprises:
four resistors electrically coupled to each other, wherein each resistor includes at least one tunnel magnetoresistive (TMR) film that includes a reference layer, a pinned layer, and a spacer layer, the spacer layer sandwiched by and contacting both the reference layer and the pinned layer, wherein the TMR films are identical in each resistor, wherein the reference layer of at least two TMR films has an antiparallel magnetic orientation and the pinned layer of the at least two TMR films has a parallel magnetic orientation, and wherein the at least two TMR films have their magnetic orientation of their reference layers aligned parallel with respect to their respective pinned layers.

16. The method of claim 15 , wherein each TMR film comprises:
a seed layer;
an antiferromagnetic layer disposed on the seed layer;
the pinned layer disposed on the antiferromagnetic layer;
the spacer layer disposed on the pinned layer;
the reference layer disposed on the spacer layer;
a barrier layer disposed on the reference layer; and
a free layer disposed on the barrier layer.

17. The method of claim 16 , wherein the seed layer and the spacer layer comprise the same material.

18. The method of claim 17 , wherein the seed layer and the spacer layer each comprise ruthenium.

19. The method of claim 15 , wherein each resistor has the same number of TMR films.

20. The method of claim 15 , wherein each resistor has the same resistance area (RA).

Assignees

• Western Digital Tech Inc

Inventors

• Zheng Yuankai
• Mao Ming
• Mauri Daniele
• Hu Chih-Ching
• Chien Chen-Jung

Classifications

• G01R33/0094

  Sensor arrays · CPC title

• G01R33/098

  comprising tunnel junctions, e.g. tunnel magnetoresistance sensors · CPC title

• G11B5/3909 Primary

  Arrangements using a magnetic tunnel junction · CPC title

• G11B5/3163

  Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers · CPC title

• G01R33/0023

  Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration (G01R33/0017 takes precedence) · CPC title