Hard magnetic bias configuration for GMR

• US 6,577,477 B1
• Filed: 02/01/2001
• Issued: 06/10/2003
• Est. Priority Date: 02/01/2001
• Status: Expired due to Fees

• Current Assignee: Headway Technologies Incorporated
• Original Assignee: Headway Technologies Incorporated
• Inventors: Lin, Chien-Li
• Primary Examiner(s): Letscher, George J.
• Application Number:
  US09/774,415
• Time in Patent Office: 859 Days
• Field of Search: 360/324.12, 360/324, 360/327.1, 360/327.3, 360/324.1, 360/324.11, 324/252, 324/207.21, 338/32.R
• US Class Current: 360/324.12
• 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: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3932 Magnetic biasing films
• CPC Class Codes: H01F 10/324 Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32

Abstract

A longitudinal bias structure for use in a GMR device is described. Improved magnetic properties of the bias structure are achieved by inserting an extra layer between the seed layer and the bias layer. This layer has lattice constants that are intermediate between those of the seed and bias layers thereby improving the crystallinity of the latter. Specifically, a layer of chromium-cobalt-tantalum is inserted between a seed layer of chromium, or chromium-titanium, and a hard magnetic (bias) layer of cobalt-chromium-platinum or cobalt-platinum. About 20 Angstroms is optimum for the thickness of this layer. Data is presented showing that significant improvements in coercivity and hysteresis loop squareness are obtained.

Claims

1. A longitudinal bias structure for use in a GMR based magnetic read head, comprising:

a substrate;

on said substrate a seed layer of chromium;

on the chromium layer a buffer layer that is an alloy of cobalt, chromium, and tantalum, said buffer layer having a thickness between about 10 and 100 Angstroms;

a layer of tantalum, between about 10 and 100 Angstroms thick, between the substrate and the seed layer; and

on the buffer layer, a magnetically hard layer that is an alloy of cobalt, chromium and platinum.

2. The structure described in claim 1 wherein the buffer layer is between about 70 and 93 atomic percent cobalt, between about 5 and 25 atomic percent chromium, and between about 2 and 10 atomic percent tantalum.

3. The structure described in claim 1 wherein the chromium layer has a thickness between about 20 and 150 Angstroms.

4. The structure described in claim 1 wherein the magnetically hard layer has a thickness between about 100 and 600 Angstroms.

5. The structure described in claim 1 wherein the magnetically hard layer is between about 50 and 93 atomic percent cobalt, between about 5 and 25 atomic percent chromium, and between about 2 and 50 atomic percent platinum.

6. A longitudinal bias structure for use in a GMR based magnetic read head, comprising:

a substrate;

on said substrate a seed layer that is an alloy of chromium and titanium;

on the chromium layer a buffer layer that is an alloy of cobalt, chromium, and tantalum, said buffer layer having a thickness between about 10 and 100 Angstroms;

a layer of tantalum, between about 10 and 100 Angstroms thick, between the substrate and the seed layer; and

on the buffer layer, a magnetically hard layer that is an alloy of cobalt, chromium and platinum.

7. The structure described in claim 6 wherein the buffer layer is between about 70 and 93 atomic percent cobalt, between about 5 and 25 atomic percent chromium, and between about 2 and 10 atomic percent tantalum.

8. The structure described in claim 6 wherein the seed layer has a thickness between about 20 and 150 Angstroms.

9. The structure described in claim 6 wherein the magnetically hard layer has a thickness between about 100 and 600 Angstroms.

10. The structure described in claim 6 wherein the magnetically hard layer is between about 50 and 93 atomic percent cobalt, between about 5 and 25 atomic percent chromium, and between about 2 and 10 atomic percent platinum.

11. The structure described in claim 6 wherein the seed layer is between about 80 and 95 atomic percent chromium and between about 5 and 20 atomic percent titanium.

12. A process for forming a longitudinal bias structure for use in a GMR based magnetic read head, comprising:

on a substrate, depositing, to a thickness between about 20 and 150 Angstroms, a seed layer that comprises chromium;

on the seed layer, depositing a buffer layer that is between about 70 and 93 atomic percent cobalt, between about 5 and 25 atomic percent chromium, and between about 2 and 10 atomic percent tantalum to a thickness between about 10 and 100 Angstroms; and

on the buffer layer, depositing, to a thickness between about 100 and 600 Angstroms, a magnetically hard layer that is between about 50 and 93 atomic percent cobalt, between about 5 and 25 atomic percent chromium, and between about 2 and 50 atomic percent platinum.

13. The process described in claim 12 further comprising depositing a layer of tantalum, between about 10 and 100 Angstroms thick, between the substrate and the seed layer.

14. The process described in claim 12 wherein the seed layer further comprises between about 80 and 95 atomic percent chromium and between about 5 and 20 atomic percent titanium.

15. A process for forming a longitudinal bias structure for use in a GMR based magnetic read head, comprising:

on a substrate, depositing, to a thickness between about 20 and 150 Angstroms, a seed layer that comprises chromium;

on the seed layer, depositing a buffer layer that is between about 70 and 93 atomic percent cobalt, between about 5 and 25 atomic percent chromium, and between about 2 and 10 atomic percent tantalum to a thickness between about 10 and 100 Angstroms; and

on the buffer layer, depositing, to a thickness between about 100 and 600 Angstroms, a magnetically hard layer that is between about 50 and 95 atomic percent cobalt and between about 5 and 50 atomic percent platinum.

16. The process described in claim 15 further comprising depositing a layer of tantalum, between about 10 and 100 Angstroms thick, between the substrate and the seed layer.

17. The process described in claim 15 wherein the seed layer further comprises between about 80 and 95 atomic percent chromium and between about 5 and 20 atomic percent titanium.