# US 7,739,787 B2 · Method of manufacturing a magnetoresistive element

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- Number: US 7,739,787 B2
- Document ID: US7739787B2
- Status: Granted
- Kind: B2
- Application number: 11/715,341
- Filed: 2007-03-08
- Published: 2007-10-18
- Granted: 2010-06-22
- Earliest claimed: 2006-04-14
- Assignees: TDK Corporation
- Inventors: Koji Shimazawa; Yoshihiro Tsuchiya; Tomohito Mizuno; Daisuke Miyauchi; Shinji Hara; Takahiko Machita
- Web page: https://patentgrep.com/patent/US7739787B2

## CPC

- G11B 5/3909: {Arrangements using a magnetic tunnel junction}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- 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 5/3929: {Disposition of magnetic thin films not used for directly coupling magnetic flux from the track to the MR film or for shielding}
- G11B 2005/3996: {large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices}
- Y10T 29/49032: Fabricating head structure or component thereof
- Y10T 29/49043: Depositing magnetic layer or coating
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

In an MR element, each of a pinned layer and a free layer includes a Heusler alloy layer. The Heusler alloy layer has two surfaces that are quadrilateral in shape and face toward opposite directions. The Heusler alloy layer includes one crystal grain that touches four sides of one of the two surfaces. In a method of manufacturing the MR element, a layered film to be the MR element is formed and patterned, and then heat treatment is performed on the layered film patterned, so that crystal grains included in a film to be the Heusler alloy layer in the layered film grow and one crystal grain that touches four sides of one of the surfaces of the film to be the Heusler alloy layer is thereby formed.

## Claims

### Claim 1

A method of manufacturing a magnetoresistive element, the magnetoresistive element comprising: a nonmagnetic layer having a first surface and a second surface that face toward opposite directions; a pinned layer disposed adjacent to the first surface of the nonmagnetic layer, a direction of magnetization in the pinned layer being fixed; and a free layer disposed adjacent to the second surface of the nonmagnetic layer, a direction of magnetization in the free layer changing in response to an external magnetic field, wherein a current for detecting magnetic signals is fed in a direction intersecting a plane of each of the forgoing layers, at least one of the pinned layer and the free layer includes a Heusler alloy layer made of a Heusler alloy and having two surfaces that are quadrilateral in shape and face toward opposite directions, and the Heusler alloy layer includes one crystal grain that touches four sides of one of the two surfaces of the Heusler alloy layer, the method comprising the steps of:
forming a layered film that will be the magnetoresistive element after undergoing patterning and heat treatment, the layered film including a film to be the pinned layer, a film to be the nonmagnetic layer, and a film to be the free layer, wherein at least one of the film to be the pinned layer and the film to be the free layer includes a film to be the Heusler alloy layer;
patterning the layered film so that the film to be the Heusler alloy layer has two surfaces that are quadrilateral in shape and face toward opposite directions; and
performing the heat treatment on the layered film after the step of patterning, so that crystal grains included in the film to be the Heusler alloy layer grow and one crystal grain that touches four sides of one of the two surfaces of the film to be the Heusler alloy layer is thereby formed.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the one of the two surfaces of the Heusler alloy layer is rectangular in shape, and a longer one of the sides of the one of the two surfaces has a length equal to or smaller than 200 nm.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the one of the two surfaces of the Heusler alloy layer has an area equal to or smaller than 10000 nm2.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the nonmagnetic layer is made of a conductive material.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the nonmagnetic layer is a tunnel barrier layer made of an insulating material.