# US 5,350,629 A · Magnetoresistive device and barrier formation process

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,350,629 A
- Document ID: US5350629A
- Status: Granted
- Kind: A
- Application number: 08/022,679
- Filed: 1993-03-01
- Granted: 1994-09-27
- Earliest claimed: 1993-03-01
- Assignees: Storage Technology Corporation
- Inventors: Yi-Shung Chaug; Victor L. Walker; Nripendra N. Roy
- Web page: https://patentgrep.com/patent/US5350629A

## CPC

- G11B 5/3903: {using magnetic thin film layers or their effects, the films being part of integrated structures}
- Y10T 428/265: 1 mil or less
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A magnetoresistive (MR) device and barrier formation process is disclosed in which a barrier layer of an aluminum-titanium oxidic compound of approximately 35 .ANG. thickness is formed between a first alumina film and an overlying material of iron bearing content, such as nickel-iron. The aluminum-titanium oxidic compound layer serves as an etchant barrier for the alumina film in a subsequent etching process to reduce or eliminate "rosette" formation otherwise occurring when etchant is trapped within pores of a porous substrate such as ferrite, ceramic or other polycrystalline material. The barrier layer also serves as a passivation layer to prevent the surface of the underlying alumina film from being modified by the transfer of ultrasonic energy during subsequent wirebonding processing which would otherwise result in film delamination at the nickel-iron/alumina layer interface.

## Claims

### Claim 1

In a thin film device having at least one aluminum oxide layer and an iron compound layer in an overlying relationship thereto, an improvement in combination therewith comprising:
an aluminum-titanium oxidic compound layer interposed between said aluminum oxide layer and said iron compound layer, wherein said aluminum oxide layer and said aluminum titanium oxide compound layer are chemically different.

### Claim 2 (depends on 1)

The thin film device of claim 1 wherein said aluminum-titanium oxidic compound layer has a thickness of 100 .ANG. or less.

### Claim 3 (depends on 1)

The thin film device of claim 1 wherein said aluminum-titanium oxidic compound layer has a thickness of substantially 35 .ANG..

### Claim 4 (depends on 1)

The thin film device of claim 1 wherein the device is an MR device.