Read sensors with improved orientation of the hard bias layer and having a nanocrystalline seed layer
View Patent ↗A system in one embodiment includes a magnetic sensor having a free magnetic layer, a nanocrystalline seed layer formed on an insulative amorphous material; a chromium-containing underlayer formed on the seed layer; and a hard bias layer formed on the underlayer and separated from the sensor by the insulative amorphous material. A method according to a further embodiment includes forming an amorphous insulative layer encapsulating a sensor stack; forming a nanocrystalline seed layer on the amorphous insulative material; forming a chromium-containing underlayer on the seed layer; and forming a hard bias layer on the underlayer. Additional systems and methods are presented.
1. A system, comprising:
a magnetic sensor having a free magnetic layer;
a nanocrystalline seed layer formed on an insulative amorphous material;
a chromium-containing underlayer formed on the seed layer; and
a hard bias layer formed on the underlayer and separated from the sensor by the insulative amorphous material.
2. The system of claim 1 , wherein the magnetic sensor is a current-perpendicular-to-plane (CPP) sensor.
3. The system of claim 1 , wherein the seed layer is MgO.
4. The system of claim 1 , wherein the seed layer is AlN.
5. The system of claim 1 , wherein the underlayer is selected from a group consisting of: Cr and CrX, where X includes at least one of W, Mo, V, and Ti.
6. The system of claim 1 , wherein the hard bias layer is selected from a group consisting of: CoPt and CoPtY, where Y includes at least one of Cr, B, and N.
7. The system of claim 1 , further comprising a cap layer formed above the hard bias layer.
8. A system, comprising:
a current-perpendicular-to-plane (CPP) sensor, comprising a metallic seed layer, a pinning layer, an artificial antiferromagnetic layer, a spacer layer, a free magnetic layer, and a cap layer;
a nanocrystalline seed layer formed along sides of the sensor stack and extending horizontally away therefrom, the seed layer being electrically insulative;
a chromium-containing underlayer preferably epitaxially formed on the nanocrystalline seed layer; and
a hard bias layer preferably epitaxially formed on the underlayer.
9. The system of claim 8 , wherein the seed layer is MgO.
10. The system of claim 8 , wherein the seed layer is AlN.
11. The system of claim 8 , wherein the underlayer is selected from a group consisting of: Cr and CrX, where X includes at least one of W, Mo, V, and Ti.
12. The system of claim 8 , wherein the hard bias layer is selected from a group consisting of: CoPt and CoPtY, where Y includes at least one of Cr, B, and N.
13. The system of claim 8 , further comprising a cap layer formed above the hard bias layer.
14. A method for forming the system of claim 8 , the method comprising:
forming the amorphous insulative layer encapsulating the sensor stack;
forming the nanocrystalline seed layer on the amorphous insulative material;
forming the chromium-containing underlayer on the seed layer; and
forming the hard bias layer on the underlayer.
15. The method of claim 14 , wherein the seed layer is consisting of MgO or AlN.
16. The method of claim 14 , wherein the chromium-containing underlayer is epitaxially formed relative to the seed layer, wherein the hard bias layer is epitaxially formed relative to the underlayer.
17. The method of claim 14 , wherein the underlayer is selected from a group consisting of: Cr and CrX, where X includes at least one of W, Mo, V, and Ti.
18. The method of claim 14 , wherein the hard bias layer is selected from a group consisting of: CoPt and CoPtY, where Y includes at least one of Cr, B, and N.
19. The method of claim 14 , further comprising annealing the seed layer for altering a nanocrystallinity thereof.
20. A method for forming the system of claim 8 , the method comprising:
forming the nanocrystalline seed layer along the sides of the sensor stack and extending horizontally away therefrom, the seed layer being electrically insulative;
epitaxially forming the chromium-containing underlayer on the seed layer; and
epitaxially forming the hard bias layer on the underlayer.
21. The method of claim 20 , wherein the seed layer is consisting of MgO or AlN.
22. The method of claim 20 , wherein the chromium-containing underlayer is epitaxially formed relative to the seed layer, wherein the hard bias layer is epitaxially formed relative to the underlayer.
23. The method of claim 20 , wherein the underlayer is selected from a group consisting of: Cr and CrX, where X includes at least one of W, Mo, V, and Ti.
24. The method of claim 20 , wherein the hard bias layer is selected from a group consisting of CoPt and CoPtY, where Y includes at least one of Cr, B, and N.
25. The method of claim 20 , further comprising annealing the seed layer for altering a nanocrystallinity thereof.