Magnetic sensor with composite magnetic shield

• US 8,945,405 B2
• Filed: 04/23/2013
• Issued: 02/03/2015
• Est. Priority Date: 07/08/2009
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Vas'ko, Vladyslav Alexandrovich, Inturi, Venkateswara Rao, Kautzky, Michael C., Lu, Zhihong, Kief, Mark T., Zhang, Yifan
• Primary Examiner(s): Deo, Duy
• Assistant Examiner(s): GATES, BRADFORD M
• Application Number:
  US13/868,515
• Publication Number:
  US 20130233823A1
• Time in Patent Office: 651 Days
• Field of Search: None
• US Class Current: 216/22
• CPC Class Codes: G11B 5/3912 Arrangements in which the active read-out elements are transducing in association with active magnetic shields, e.g. magnetically coupled shields G11B5/3916 takes precedence
• CPC Class Codes: G11B 5/398 Specially shaped layers
• CPC Class Codes: G11B 5/84 Processes or apparatus specially adapted for manufacturing record carriers

Abstract

A magneto-resistive reader includes a first magnetic shield element, a second magnetic shield element and a magneto-resistive sensor stack separating the first magnetic shield element from the second magnetic shield element. The first shield element includes two ferromagnetic anisotropic layers separated by a grain growth suppression layer.

Claims

1. A method of forming a magneto-resistive reader comprising:

depositing a first shield element, the first shield element comprising two ferromagnetic anisotropic layers separated by a grain growth suppression layer;

annealing the first shield element at a magnetic set anneal temperature to form a set annealed first shield;

depositing a magneto-resistive sensor stack on the annealed first shield;

annealing the magneto-resistive sensor stack at a magnetic cross set anneal temperature to form a cross set annealed magneto-resistive sensor stack; and

depositing a second shield element on the cross set annealed magneto-resistive sensor stack.

2. A method according to claim 1, wherein the magnetic set anneal temperature is greater than 390 degrees centigrade.

3. A method according to claim 1, wherein the magnetic cross set anneal temperature is greater than 300 degrees centigrade.

4. A method according to claim 1, wherein the grain growth suppression layer has a thickness of less than 100 Angstroms.

5. A method according to claim 4, wherein the grain growth suppression layer is non-magnetic.

6. A method according to claim 1, wherein the magnetic cross set anneal step comprises applying a magnetic field that is perpendicular a magnetization orientation direction of the first shield element.

7. A method according to claim 1, wherein the magnetic cross set anneal temperature less than the magnetic set anneal temperature.

8. A method according to claim 1, wherein the magneto-resistive sensor stack is a tunneling magneto-resistive reader having a TMR ratio of 200% or greater.

9. A method according to claim 1, wherein the ferromagnetic anisotropic layers comprise NiFe and the grain growth suppression layer comprises Ru.

10. A method according to claim 1, wherein the ferromagnetic anisotropic layers comprise NiFe and the grain growth suppression layer comprises or Ta.

11. A method according to claim 1, wherein the ferromagnetic anisotropic layers comprise NiFe and the grain growth suppression layer comprises Nb, Zr or Hf.

12. A method according to claim 1, wherein the two ferromagnetic anisotropic layers have about equal thicknesses.

13. A method according to claim 1, wherein the grain growth suppression layer inhibits diffusion, defect mobility, and grain crystallization during magnetic annealing of the magneto-resistive reader.

14. A method according to claim 1, wherein the first magnetic shield element further comprises a third ferromagnetic anisotropic layer, and a second grain growth suppression layer is located between the third ferromagnetic anisotropic layer and the second ferromagnetic anisotropic layer.

15. A method of forming a first shield for a tunneling magneto-resistive reader comprising:

depositing a first shield element, the first shield element comprising two ferromagnetic anisotropic layers separated by a grain growth suppression layer;

annealing the first shield element at a magnetic set anneal temperature to form a set annealed first shield;

polishing an exposed surface of the first shield element to form a smooth exposed first shield surface;

depositing a chemical mechanical polishing stop layer on the smooth exposed first shield surface;

depositing an insulating material about the first shield element;

removing insulating material by chemical mechanical polishing down to the chemical mechanical polishing stop layer;

removing the chemical mechanical polishing stop layer, forming a polished first shield element;

depositing a magneto-resistive sensor stack on the polished first shield;

annealing the magneto-resistive sensor stack at a magnetic cross set anneal temperature to form a cross set annealed magneto-resistive sensor stack.

16. A method according to claim 15, wherein the polishing step removes less than 2% of the ferromagnetic anisotropic layer being polished.

17. A method according to claim 15, wherein the polishing step removes less than 1% of the ferromagnetic anisotropic layer being polished.

18. A method according to claim 15, wherein the magneto-resistive sensor stack is a tunneling magneto-resistive reader having a TMR ratio of 100% or greater.

19. A method according to claim 15, wherein the magneto-resistive sensor stack is a tunneling magneto-resistive reader having a TMR ratio of 100% or greater.