# US 7,610,674 B2 · Method to form a current confining path of a CPP GMR device

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- Number: US 7,610,674 B2
- Document ID: US7610674B2
- Status: Granted
- Kind: B2
- Application number: 11/352,676
- Filed: 2006-02-13
- Published: 2007-08-16
- Granted: 2009-11-03
- Earliest claimed: 2006-02-13
- Assignees: Headway Technologies, Inc.
- Inventors: Kunliang Zhang; Daniel G Abels; Min Li; Yu-Hsia Chen
- Web page: https://patentgrep.com/patent/US7610674B2

## CPC

- G11B 5/398: {Specially shaped layers}
- B82Y 25/00: Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
- G01R 33/093: {using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00)}
- G11B 5/3906: {Details related to the use of magnetic thin film layers or to their effects}
- H10N 50/01: Manufacture or treatment
- H10N 50/10: Magnetoresistive devices
- Y10T 29/49044: Plural magnetic deposition layers
- Y10T 29/49046: with etching or machining of magnetic material
- Y10T 29/49048: Machining magnetic material [e.g., grinding, etching, polishing]
- Y10T 29/49052: by etching
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Concerns about inadequate electromigration robustness in CCP CPP GMR devices have been overcome by adding magnesium to the current confining structures that are presently in use. In one embodiment the alumina layer, in which the current carrying copper regions are embedded, is fully replaced by a magnesia layer. In other embodiments, alumina is still used but a layer of magnesium is included within the structure before it is subjected to ion assisted oxidation.

## Claims

### Claim 1

A method to form a current confining path as part of a CPP GMR device, comprising:
providing a magnetically pinned layer and depositing thereon a first copper layer;
depositing a layer of MgCu alloy on said first copper layer;
following a pre-treatment, subjecting said MgCu layer to ion assisted oxidation whereby said MgCu layer segregates into regions of magnesia and free copper;
depositing a second copper layer on said copper-magnesia layer, whereby current flow between said first and second copper layers is confined to said regions of free copper; and
depositing a magnetically free layer on said second copper layer.

### Claim 2 (depends on 1)

The method of claim 1 wherein said MgCu alloy has a composition of Mg (1-x)Cu(x) where x ranges from about 5 atomic % to about 60 atomic %.

### Claim 3 (depends on 1)

The method of claim 1 wherein said pre-treatment further comprises etching in a low power plasma and said ion assisted oxidation further comprises exposure to an ionized argon oxygen mixture.

### Claim 4 (depends on 1)

The method of claim 1 wherein said magnesium-copper alloy layer has a thickness between about 5 and 15 Angstroms.

### Claim 5 (depends on 1)

The method of claim 1 wherein said first and second copper layers each have a thickness between about 1 and 7 Angstroms.