In-situ oxidized films for use as cap and gap layers in a spin-valve sensor and methods of manufacture

• US 20030030944A1
• Filed: 07/31/2001
• Published: 02/13/2003
• Est. Priority Date: 07/31/2001
• Status: Active Grant

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Hitachi Global Storage Technologies Netherlands BV (Western Digital Corporation)
• Inventors: Mauri, Daniele, Lin, Tsann
• Granted Patent: US 6,709,767 B2
• Time in Patent Office: Days
• US Class Current: 360/324.1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: Y10T 29/49044 Plural magnetic deposition layers
• CPC Class Codes: Y10T 428/1129 Super lattice [e.g., giant magneto resistance [GMR] or colossal magneto resistance [CMR], etc.]
• CPC Class Codes: Y10T 428/1164 with protective film
• CPC Class Codes: Y10T 428/1171 with defined laminate structural detail
• CPC Class Codes: Y10T 428/12549 Adjacent to each other
• CPC Class Codes: Y10T 428/1259 Oxide
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12646 Group VIII or IB metal-base
• CPC Class Codes: Y10T 428/12667 Oxide of transition metal or Al
• CPC Class Codes: Y10T 428/1291 Next to Co-, Cu-, or Ni-base component
• CPC Class Codes: Y10T 428/12917 Next to Fe-base component
• CPC Class Codes: Y10T 428/12931 Co-, Fe-, or Ni-base components, alternative to each other
• CPC Class Codes: Y10T 428/12937 Co- or Ni-base component next to Fe-base component
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

Disclosed is a spin-valve sensor employing one or more in-situ oxidized films as cap and/or gap layers in order to achieve an increased GMR coefficient and improved thermal stability. A fabrication method comprises depositing multilayer metallic films on a wafer in ion-beam and DC-magnetron sputtering modules of a sputtering system, and then transferring the wafer in a vacuum to an oxidation module where in-situ oxidation is conducted. When the method is used to form a cap layer, the cap layer may only be partially oxidized. A magnetic-field annealing may be subsequently conducted without the substantial occurrence of interface mixing and oxygen diffusion during the anneal process. The resulting spin-valve sensor exhibits an increased GMR coefficient, possibly due to induced specular scattering of conduction electrons and improved thermal stability mainly due to the protection of an underlying sensing layer from interface mixing and oxygen diffusion during the annealing process. Gap layers may also be formed from multi-layer in-situ deposition and oxidation of metal films. Smaller, more sensitive spin-valve sensors may be fabricated through the use of the alternative deposition and in-situ oxidization of the metallic films, thus allowing for greater recording data densities in disk drive systems.

Claims

1. A spin-valve sensor comprising:

an antiferromagnetic pinning layer;

a pinned layer disposed to one side of the antiferromagnetic pinning layer;

a sensing layer;

a spacer layer disposed between the pinned layer and the sensing layer; and

a cap layer disposed to one side of the sensing layer, the cap layer comprising a partially oxidized metal film.

2. The spin-valve sensor of claim 1, further comprising a conducting seed layer disposed subjacent the antiferromagnetic pinning layer;

the conducting seed layer comprising an Al₂O₃ film, an Ni-Cr-Fe film and a Ni-Fe film;

the antiferromagnetic pinning layer formed of a Pt-Mn film;

the pinned layer formed of a Co-Fe film, an intervening Ru film, and a Co-Fe film;

the spacer layer formed of an oxygen-doped, in-situ oxidized Cu film;

the sensing layer formed of a Co-Fe film and a Ni-Fe film; and

the cap layer formed of a partially in-situ oxidized metal film.

3. The spin-valve sensor of claim 2, wherein the partially oxidized metal film comprises Al and Al-O

4. The spin-valve sensor of claim 1, wherein the partially oxidized metal film comprises Al and Al-O.

5. The spin-valve sensor of claim 1, wherein the partially oxidized metal film comprises an in-situ oxidized metal film.

6. The spin-valve sensor of claim 1, wherein the partially oxidized metal film comprises an in-situ oxidized, Al and Al-O film.

7. The spin-valve sensor of claim 1, wherein the partially oxidized metal film has a thickness in the range of between about 5 Å

and about 15 Å

.

8. The spin-valve sensor of claim 1, wherein the partially oxidized metal film has a thickness in the range of between about 8 Å

and about 12 Å

.

9. The spin-valve sensor of claim 1, wherein the partially oxidized metal film comprises Al with a thickness in a range of between about 1 Å

and about 5 Å and

Al-O with a thickness in a range of between about 5 Å

and about 9 Å

.

10. The spin-valve sensor of claim 1, further comprising an additionally partially oxidized metal film disposed between the cap layer and the sensing layer.

11. The spin-valve sensor of claim 10, wherein the additional partially oxidized metal film comprises an in-situ oxidized metal film selected from the group consisting of Au, Cu, Rh, or Ru film and has a thickness in the range of between about 8 Å

and about 12 Å

.

12. The spin-valve sensor of claim 1, further comprising a top gap layer disposed directly adjacent to the cap layer, and a bottom gap layer disposed to one side of the antiferromagnetic pinning layer..

13. The spin-valve sensor of claim 12, wherein at least one of the top gap layer and the bottom gap layer is formed of an in-situ oxidized metal film.

14. The spin-valve sensor of claim 12, wherein at least one of the top gap layer and the bottom gap layer is formed of a plurality of oxidized metal films.

15. The spin-valve sensor of claim 12, wherein the bottom gap layer and the top gap layer are each formed of a plurality of in-situ oxidized metal films.

16. The spin-valve sensor of claim 12, wherein the bottom gap layer and the top gap layer are each formed of a plurality of in-situ oxidized Al metal films.

32. The method of claim 1, further comprising forming an additional partially in-situ oxidized metal film between the cap layer and the sensing layer.

33. The method of claim 32, wherein the additional partially in-situ oxidized metal film comprises Cu.

17. A disk drive system comprising:

a magnetic recording disk;

a spin-valve sensor for reading data recorded on the recording disk, the spin-valve sensor comprising;

a substrate;

an antiferromagnetic layer (AFM) disposed to one side of the substrate;

a pinned layer formed of ferromagnetic material and positioned adjacent the antiferromagnetic layer, the magnetic orientation of the pinned layer substantially fixed by the antiferromagnetic layer, and the pinned layer comprising a layer of an electrically resistive material selected to reduce the amount of current traveling from the pinned layer to the antiferromagnetic layer;

a sensing layer of ferromagnetic material positioned adjacent the pinned layer, the sensing layer configured to have an electrical resistance that changes in response to changes in magnetic flux through the sensing layer; and

a cap layer disposed to one side of the sensing layer, the cap layer formed of a partially in-situ oxidized metal film having a thickness of in the range of between about 5 and about 15 Å

; and

an actuator for moving the spin valve sensor across the magnetic recording disk in order for the spin-valve sensor to access different magnetically recorded data on the magnetic recording disk; and

a detector electrically coupled to the spin-valve sensor and configured to detect changes in resistance of the sensor caused by rotation of the magnetization of the sensing layer relative to the fixed magnetizations of the pinned layer in response to changing magnetic fields induced by the magnetically recorded data.

18. A method of forming a spin-valve sensor, the method comprising:

forming an antiferromagnetic pinning layer;

forming a pinned layer to one side of the antiferromagnetic pinning layer;

forming a sensing layer;

forming a spacer layer disposed between the pinned layer and the sensing layer; and

forming a cap layer disposed to one side of the sensing layer by deposition and in-situ oxidation of a metal film.

19. The method of claim 18, wherein deposition and in-situ oxidation of the metal film comprises depositing the metal film in a chamber substantially devoid of oxygen and transferring the film to an oxidation chamber in a vacuum and introducing oxygen to the metal film in the oxidation chamber in a controlled environment.

20. The method of claim 19, wherein depositing a metal film comprises depositing an Al film.

21. The method of claim 19, wherein deposition and in-situ oxidation of the metal film comprises DC magnetron sputtering and in-situ oxidation for a time in the range of between about 1 to about 100 minutes in oxygen gas with a pressure in the range of between about 0.1 to about 10 Torr.

22. The method of claim 19, wherein introducing oxygen comprises introducing oxygen with a pressure in the range of between about 0.4 and 0.6 Torr.

23. The method of claim 19, wherein introducing oxygen comprises introducing oxygen with a pressure in the range of between about 0.45 Torr and about 0.55 Torr.

24. The method of claim 19, wherein introducing oxygen comprises introducing oxygen with a pressure of about 0.5 Torr.

25. The method of claim 19, wherein introducing oxygen comprises introducing oxygen for a period in the range of between about 4 and about 12 minutes.

26. The method of claim 19, wherein introducing oxygen comprises introducing oxygen for a period in a range of between about 6 minutes and about 10 minutes.

27. The method of claim 19, wherein introducing oxygen comprises introducing oxygen for a period of about 8 minutes.

28. method of claim 19, wherein introducing oxygen is conducted with a temperature of approximately ambient room temperature.

29. The method of claim 18, further comprising forming a protective gap layer.

30. The method of claim 29, wherein forming the protective gap layer comprises forming a plurality of oxidized metal layers.

31. The method of claim 30, wherein forming a plurality of oxidized metal layers comprises forming a plurality of in-situ oxidized aluminum layers, each having a thickness in the range of between about 5 and about 15 Å

.