# US 2009/0262575 A1 · Thin film magnetic memory device capable of conducting stable data read and write operations

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- Number: US 2009/0262575 A1
- Document ID: US20090262575A1
- Status: Published application
- Kind: A1
- Application number: 12/494,725
- Filed: 2009-06-30
- Published: 2009-10-22
- Earliest claimed: 2001-04-26
- Assignees: Renesas Technology Corp.
- Inventors: Hideto Hidaka
- Web page: https://patentgrep.com/patent/US20090262575A1

## CPC

- H10B 61/22: {of the field-effect transistor [FET] type}
- G11C 7/14: Dummy cell management; Sense reference voltage generators
- G11C 11/16: using elements in which the storage effect is based on magnetic spin effect
- G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell}
- G11C 11/1657: {Word-line or row circuits}
- G11C 11/1659: {Cell access}
- G11C 11/1673: {Reading or sensing circuits or methods}
- G11C 11/1675: {Writing or programming circuits or methods}
- H10B 61/10: {comprising components having two electrodes, e.g. diodes or MIM elements}
- H10B: ELECTRONIC MEMORY DEVICES
- G11C: STATIC STORES (semiconductor memory devices H10B)

## Abstract

A tunnel magnetic resistive element forming a magnetic memory cell includes a fixed magnetic layer having a fixed magnetic field of a fixed direction, a free magnetic layer magnetized by an applied magnetic field, and a tunnel barrier that is an insulator film provided between the fixed and free magnetic layers in a tunnel junction region. In the free magnetic layer, a region corresponding to an easy axis region having characteristics desirable as a memory cell is used as the tunnel junction region. A hard axis region having characteristics undesirable as a memory cell is not used as a portion of the tunnel magnetic resistive element.

## Claims

### Claim at position 1

1-12. (canceled)

### Claim 13

A thin film magnetic memory device, comprising:
a plurality of magnetic memory cells for retaining storage data written by an applied magnetic field; and
a dummy memory cell for generating a read reference voltage in data read operation, wherein
each of said magnetic memory cells and said dummy memory cell include
a magnetic storage portion having either a first electric resistance value or a second electric resistance value that is higher than said first electric resistance value depending on a level of said storage data, and
an access gate connected in series with said magnetic storage portion, and selectively turned ON, said thin film magnetic memory device further comprising:
a first data line that is electrically coupled to a magnetic memory cell selected from said plurality of magnetic memory cells in data read operation so that a data read current is supplied to said first data line;
a second data line that is electrically coupled to said dummy memory cell in data read operation so that a data read current equal to that of said first data line is supplied to said second data line;
a data read circuit for producing read data based on respective voltages on said first and second data lines; and
a resistance adding circuit for adding a third electric resistance in series with said first data line, said third electric resistance being smaller than a difference between said first and second electric resistance values, wherein
said magnetic storage portion in said dummy memory cell stores a data level corresponding to said second electric resistance value.

### Claim 14 (depends on 13)

The thin film magnetic memory device according to claim 13, wherein said resistance adding circuit includes a field effect transistor receiving a variable control voltage at its gate.