Magnetic sensor array with single TMR film plus laser annealing and characterization
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.
1. A tunnel magnetoresistive (TMR) sensor device, comprising:
a first resistor comprising at least one first TMR film having a first reference layer, first pinned layer, and a first spacer layer, the first spacer layer sandwiched by and contacting both the first reference layer and the 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, second pinned layer, and a second spacer layer, the second spacer layer sandwiched by and contacting both the second reference layer and the second pinned layer, wherein the first TMR film and the second TMR film are substantially identical, wherein the first reference layer and the second reference layer have an antiparallel magnetic orientation, wherein the first pinned layer and the second pinned layer have a parallel magnetic orientation, and wherein the magnetic orientation of the second pinned layer is parallel to the magnetic orientation of the second reference layer.
2. The TMR sensor device of claim 1 , 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.
3. The TMR sensor device of claim 2 , 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.
4. The TMR sensor device of claim 3 , wherein the first TMR film, the second TMR film, the third TMR film, and the fourth TMR film are substantially identical.
5. The TMR sensor device of claim 4 , 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.
6. The TMR sensor device of claim 1 , 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.
7. The TMR sensor device of claim 1 , 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.
8. The TMR sensor device of claim 1 , wherein the first resistor and the second resistor have the same resistance area (RA).
9. The TMR sensor device of claim 1 , wherein the first TMR film further comprises a first antiferromagnetic layer disposed in contact with the first pinned layer, the first antiferromagnetic layer pinning the magnetic orientation of the first pinned layer.
10. The TMR sensor device of claim 1 , wherein the magnetic orientation of the first pinned layer is antiparallel to the magnetic orientation of the first reference layer.
11. The TMR sensor device of claim 1 , wherein the second TMR film further comprises a second antiferromagnetic layer disposed in contact with the second pinned layer, the second antiferromagnetic layer pinning the magnetic orientation of the second pinned layer.
12. The TMR sensor device of claim 1 , wherein the first reference layer and the second reference layer each individually comprise a multilayer stack of materials.
13. A TMR sensor device, comprising:
four resistors electrically coupled to each other, wherein each resistor includes at least one tunnel magnetoresistive (TMR) film that includes a reference layer, 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, and 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, wherein the at least two TMR films have their magnetic orientation of their reference layers aligned parallel with respect to their respective pinned layers.
14. The TMR sensor device of claim 13 , 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.
15. The TMR sensor device of claim 14 , wherein the seed layer and the spacer layer comprise the same material.
16. The TMR sensor device of claim 15 , wherein the seed layer and the spacer layer each comprise ruthenium.
17. The TMR sensor device of claim 13 , wherein each resistor has the same number of TMR films.
18. The TMR sensor device of claim 13 , wherein each resistor has the same resistance area (RA).