Back to results
US 6,788,568 B2Granted
Thin film magnetic memory device capable of conducting stable data read and write operations
AssigneeRenesas Technology Corp.
InventorHideto Hidaka
Life of this patent
Estimating the term…
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.
Claims10
A thin film magnetic memory device, comprising:
- a plurality of memory cells for retaining storage data, wherein
- each of said memory cells includes
- an access gate selectively turned ON in data read operation, and
- a magnetic storage portion connected in series with said access gate, and having either a first electric resistance or a second electric resistance higher than said first electric resistance depending on said storage data, and
- said magnetic storage portion includes
- a first magnetic layer having a fixed magnetization direction,
- a second magnetic layer that is magnetized in a same direction as, or in a direction opposite to, that of said first magnetic layer depending on said storage data to be written, and
- a first insulating film formed between said first and second magnetic layers, said thin film magnetic memory device further comprising:
- a data line that is electrically coupled to the magnetic storage portion of a selected memory cell through a turned-ON access gate of said selected memory cell in data read operation, said selected memory cell being a memory cell selected from said plurality of memory cells for said data read operation;
- a reference data line for transmitting in said data read operation a read reference voltage for comparison with a voltage on said data line;
- and
- a plurality of dummy memory cells for producing said read reference voltage, each of said dummy memory cells being provided for every fixed set of said memory cells, wherein
- each of said dummy memory cells includes
- a dummy access gate selectively turned ON in said data read operation, and
- a plurality of dummy magnetic storage portions that are electrically coupled to said reference data line in response to turning-ON of said dummy access gate,
- each of said dummy magnetic storage portions includes
- a third magnetic layer that is magnetized in a fixed direction,
- a fourth magnetic layer that is magnetized either in a same direction as, or in a direction opposite to, that of said third magnetic layer, and
- a second insulating film formed between said third and fourth magnetic layers, and
- each of said dummy magnetic storage portions is connected in series with at least another one of the plurality of dummy magnetic storage portions.
17 more elements
A thin film magnetic memory device, comprising:
- a plurality of memory cells for storing data, wherein
- each of said memory cells includes
- an access gate selectively turned ON in data read operation, and
- a magnetic storage portion connected in series with said access gate, and having either a first electric resistance or a second electric resistance higher than said first electric resistance depending on the stored data, and
- said magnetic storage portion includes
- a first group of magnetic elements in a first layer having a fixed magnetization direction,
- a second group of magnetic elements in a second layer that is magnetized in a same direction as, or in a direction opposite to, that of said first group of magnetic elements depending on the data to be written, and
- a first insulating film formed between said first and second groups of magnetic elements,
- said thin film magnetic memory device further comprising:
- a data line that is electrically coupled to a selected memory cell through a turned-ON access gate of said selected memory cell in said data read operation, said selected memory cell being a memory cell selected from said plurality of memory cells for said data read operation;
- a reference data line for transmitting in said data read operation a read reference voltage for comparison with a voltage on said data line;
- and
- a plurality of dummy memory cells for producing said read reference voltage, each of said dummy memory cells being provided for every fixed set of said memory cells, wherein
- each of said dummy memory cells includes
- a dummy access gate selectively turned ON in said data read operation, and
- a plurality of dummy magnetic storage portions that are electrically coupled to said reference data line in response to turning-ON of said dummy access gate,
- each of said dummy magnetic storage portions includes
- a third group of magnetic elements in a first layer that is magnetized in a fixed direction,
- a fourth group of magnetic elements in a second layer that is magnetized either in a same direction as, or in a direction opposite to, that of said third group of magnetic elements magnetic, and
- a second insulating film formed between said third and fourth groups of magnetic elements, and
- each of said dummy magnetic storage portions is connected in series with at least another one of the plurality of dummy magnetic storage portions.
18 more elements
Dependencies are inferred from the claim text.