Enhanced anti-parallel-pinned sensor using thin ruthenium spacer and high magnetic field annealing
View Patent ↗An anti-parallel pinned sensor is provided with a spacer that increases the anti-parallel coupling strength of the sensor. The anti-parallel pinned sensor is a GMR or TMR sensor having a pure ruthenium or ruthenium alloy spacer. The thickness of the spacer is less than 0.8 nm, preferably between 0.1 and 0.6 nm. The spacer is also annealed in a magnetic field that is 1.5 Tesla or higher, and preferably greater than 5 Tesla. This design yields unexpected results by more than tripling the pinning field over that of typical AP-pinned GMR and TMR sensors that utilize ruthenium spacers which are 0.8 nm thick and annealed in a relatively low magnetic field of approximately 1.3 Tesla.
1. A method of increasing the coupling strength of a sensor, the method comprising:
(a) providing a ruthenium spacer having a thickness of less than 0.8 nm;
(b) forming a sensor with the ruthenium spacer; and
(c) annealing the ruthenium spacer in a magnetic field that is greater than 2.5 Tesla.
2. The method of claim 1 , wherein the sensor is an anti-parallel pinned sensor.
3. The method of claim 1 , wherein the sensor is selected from the group consisting of GMR and TMR sensors.
4. The method of claim 1 , wherein the ruthenium spacer is a ruthenium alloy.
5. The method of claim 1 , wherein the ruthenium spacer is pure ruthenium.
6. The method of claim 1 , wherein the thickness of the ruthenium spacer is between 0.1 and 0.6 nm.
7. A method of increasing the anti-parallel coupling strength of an anti-parallel pinned sensor, the method comprising:
(a) providing a ruthenium spacer having a thickness of less than 0.8 nm;
(b) forming an anti-parallel pinned sensor with the ruthenium spacer; and
(c) annealing the ruthenium spacer in a magnetic field that is greater than 2.5 Tesla.
8. The method of claim 7 , wherein the anti-parallel pinned sensor is selected from the group consisting of GMR and TMR sensors.
9. The method of claim 7 , wherein the ruthenium spacer is a ruthenium alloy.
10. The method of claim 7 , wherein the ruthenium spacer is pure ruthenium.
11. The method of claim 7 wherein the thickness of the ruthenium spacer is between 0.1 and 0.6 nm.