Multi-layer magnetic random access memory using spin-torque magnetic tunnel junctions and method for write state of the multi-layer magnetic random access memory
AssigneeInternational Business Machines Corporation
InventorWilliam R. Reohr
Life of this patent
Estimating the term…
Abstract
A stacked magnetic tunnel junction (MTJ) structure of a multi-layer magnetic random access memory (MRAM) which includes a plurality of stacked MTJ devices serially connected to each other and an access transistor shared between the stacked MTJ devices. The stacked MTJ structure further includes a write word line through which a write current flows. The write current generates a hard axis magnetic field used to selectively write an MTJ device of the stacked MTJ devices.
Claims18
A stacked magnetic tunnel junction structure of a multi-layer magnetic random access memory comprising:
- a plurality of stacked magnetic tunnel junction devices serially connected to each other, and an access transistor shared between the stacked magnetic tunnel junction devices;
- and
- a write word line through which a write current flows, the write current generating a hard axis magnetic field used to selectively write a magnetic tunnel junction device of the stacked magnetic tunnel junction devices, wherein when a magnetic tunnel junction device of the stacked magnetic tunnel junction devices is selected to be written and the write current flows through the respective write word line to generate a hard axis magnetic field, a cancel current is generated and flows through the respective write word line of an unselected magnetic tunnel junction device to cancel stray magnetic field of the hard axis magnetic field which impinges on the unselected magnetic tunnel junction device.
A stacked magnetic tunnel junction structure of a multi-layer magnetic random access memory having first and second layers, comprising:
- a plurality of stacked magnetic tunnel junction devices serially connected to each other;
- and
- a switching network which sources a first current on one of the first or second layers to select a magnetic tunnel junction device of the stacked magnetic tunnel junction devices for writing and sources a second current on the other of the first or second layers to cancel a magnetic field produced by the first current which impinges on an unselected magnetic tunnel junction device of the stacked magnetic tunnel junction devices, the first current having a greater magnitude than that of the second current.
A write method for selectively writing a magnetic tunnel junction device of stacked magnetic tunnel junction devices, the method comprising:
- selecting a magnetic tunnel junction device of the stacked magnetic tunnel junction devices for writing data;
- generating a write current to flow through a first write word line corresponding to the MTJ device selected to generate a hard axis magnetic field which selects the magnetic tunnel junction device for writing;
- generating a cancel current to flow through a second write word line corresponding to an unselected magnetic tunnel junction device of the stacked magnetic tunnel junction devices to generate an opposing magnetic field to counterbalance a stray magnetic field of the hard axis magnetic field which impinges on the unselected magnetic tunnel junction device.
Dependencies are inferred from the claim text.