US 8,804,413 B2Granted

Multi-free layer MTJ and multi-terminal read circuit with concurrent and differential sensing

AssigneeQUALCOMM Incorporated

InventorsXia Li, Wenqing Wu, Jung Pill Kim, Xiaochun Zhu, Seung H. Kang, Raghu Sagar Madala, Kendrick H. Yuen

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Abstract

A multi-free layer magnetic tunnel junction (MTJ) cell includes a bottom electrode layer, an anti-ferromagnetic layer on the bottom electrode layer, a fixed magnetization layer on the anti-ferromagnetic layer and a barrier layer on the fixed magnetization layer. A first free magnetization layer is on a first area of the barrier layer, and a capping layer is on the first free magnetization layer. A free magnetization layer is on a second area of the barrier layer, laterally displaced from the first area, and a capping layer is on the second free magnetization layer. Optionally current switches establish a read current path including the first free magnetization layer concurrent with not establishing a read current path including the second free magnetization layer. Optionally current switches establishing a read current path including the first and second free magnetization layer.

Claims17

Dependent claims

A multi-free layer magnetic tunnel junction (MTJ) cell comprising:

a bottom electrode layer;
an anti-ferromagnetic (AFM) layer on the bottom electrode layer;
a fixed magnetization layer on the anti-ferromagnetic layer;
a barrier layer on the fixed magnetization layer;
a first free magnetization layer on a first area of the barrier layer;
a second free magnetization layer on a second area of the barrier layer, laterally displaced from the first area;
a first top electrode coupled to the first free magnetization layer and a second top electrode coupled to the second free magnetization layer;
a first read/write terminal coupled to a first bit/select line;
a first current switch configured to receive a first control line signal switchable between an ON voltage and an OFF voltage and, in response, to respectively switch between coupling and not coupling the first top electrode to the first read/write terminal;
a second read/write terminal coupled to a second bit/select line;
a second current switch configured to receive a second control line signal switchable between an ON voltage and an OFF voltage and, in response, to respectively switch between coupling and not coupling the second top electrode to the second read/write terminal;
a third read/write terminal coupled to a third bit/select line;
and
a third current switch configured to receive a third control line signal switchable between an ON voltage and an OFF voltage and, in response, to respectively switch between coupling and not coupling the bottom electrode layer to the third read/write terminal.

11 more elements

A method for magnetic tunnel junction (MTJ) memory, comprising:

injecting a first write current from one of a first read/write terminal and a base read/write terminal to the other of the first read/write terminal and the base read/write terminal, the first write current passing through a first free magnetization layer;
injecting a second write current from one of a second read/write terminal and the base read/write terminal to the other of the second read/write terminal and the base read/write terminal, the second write current passing through a second free magnetization layer;
detecting a magnetization state of the first free magnetization layer;
and
detecting a magnetization state of the second free magnetization layer, wherein detecting the magnetization state of the second free magnetization layer is based in part on a result of detecting the magnetization state of the first free magnetization layer.

2 more elements

A method for magnetic tunnel junction (MTJ) memory storage of a multi-bit data, comprising:

storing a first bit by injecting a first write current, based on said first bit, from one of a first read/write MTJ terminal and a base read/write MTJ terminal to the other of the first read/write MTJ terminal and the base read/write MTJ terminal, the first write current passing through a first free magnetization layer to place the first free magnetization layer in a state indicating the first bit;
storing a second bit by injecting a second write current, based on said second bit, from one of a second read/write MTJ terminal and the base read/write MTJ terminal to the other of the second read/write MTJ terminal and the base read/write MTJ terminal, the second write current passing through a second free magnetization layer to place the second free magnetization layer in a state indicating the second bit;
reading the first bit, wherein reading the first bit comprises
injecting a first read current into one of the first read/write terminal and the base read/write terminal, through the first free magnetization layer and not through second free magnetization layer, and out of the other of the first read/write terminal and the base read/write terminal, to generate a first sense voltage on one of the first read/write terminal and the base read/write terminal,
comparing the first sense voltage to a first reference,
detecting the first bit based on the comparing the first sense voltage to the first reference;
and
reading the second bit, wherein reading the second bit comprises
selecting, as a selected reference, between a second reference and a third reference, based on a result of detecting the first bit,
injecting a second read current into one of the first read/write terminal and the through read/write terminal, through a succession of the first free magnetization layer and the second free magnetization layer, and out of the other of the first read/write terminal and the second read/write terminal, to generate, on one of the first read/write terminal and the second read/write terminal, a second sense voltage,
comparing the second sense voltage to the selected reference, and
detecting the second bit based on the comparing the second sense voltage to the selected reference.

9 more elements

An apparatus for magnetic tunnel junction (MTJ) memory, comprising:

means for injecting a first write current from one of a first read/write terminal and a base read/write terminal to the other of the first read/write terminal and the base read/write terminal, the first write current passing through a first free magnetization layer;
means for injecting a second write current from one of a second read/write MTJ terminal and the base read/write terminal to the other of the second read/write MTJ terminal and the base read/write terminal, the second write current passing through a second free magnetization layer;
means for detecting a magnetization state of the first free magnetization layer;
and
means for detecting a magnetization state of the second free magnetization layer based, in part, on a result of detecting the magnetization state of the first free magnetization layer.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/586,934Filed 16 Aug 2012 · us provisional application
Priority: 7 Feb 2012
Published: US 2013/0201757 A18 Aug 2013
Granted: 12 Aug 2014
Term ends: Not estimatedThe source records don’t support an estimate.

Classification16 codes

G11C 11/16
Using magnetic elements: using elements in which the storage effect is based on magnetic spin effect
G11C 11/15
Using thin-film elements: using multiple magnetic layers
G11C 11/161
Using elements in which the storage effect is based on magnetic spin effect: details concerning the memory cell structure, e.g. the layers of the…
G11C 11/1659
Auxiliary circuits: cell access