US 2007/0164380 A1Published application

MRAM with split read-write cell structures

AssigneeMagIC Technologies, Inc.

InventorsTai Min, Po-Kang Wang

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Abstract

An MRAM cell is formed in two separate portions. A first portion, that includes a pinned layer, a tunneling barrier layer and first free layer part, is used to read the value of a stored bit of information. A second portion includes a second free layer part on which information is written and stored. The second free layer part is formed with a high aspect ratio cross-section that renders it strongly magnetically anisotropic and enables it to couple to the relatively isotropic first free layer through a magnetostatic interaction. This interaction aligns the magnetization of the first free layer part in an opposite direction to the magnetization of the second free layer part. The magnetic orientation of the first free layer part relative to that of its adjacent pinned layer determines the resistance state of the first cell portion and this resistance state can be read by passing a current through the first cell portion. Thus, in effect, the first cell portion becomes a remote sensing device for the magnetization orientation of the second free layer part

Claims25

Dependent claims

An MRAM cell having a free layer formed in two magnetized parts, a first free layer part for reading stored information and a second free layer part for writing and storing said information comprising:

a first cell portion for reading stored information including a pinned layer, a tunneling barrier layer and a first free layer part, said first cell portion having a resistance value depending on the relative orientations of the magnetization of said first free layer part and the magnetization of said pinned layer;
and said first free layer part having very little or no magnetic anisotropy or having magnetic anisotropy wherein an easy magnetic axis of said first free layer part is directed perpendicularly to an easy magnetic axis of said second free layer part;
and
a second cell portion including said second free layer part, in which said second cell portion information can be written and stored in accord with the magnetization direction of said second free layer part and said second free layer part having a magnetic anisotropy to maintain said magnetization direction;
and wherein
the horizontal dimensions of said first and second free layer parts and a spacing formed therebetween permits the formation of a magnetostatic interaction between said first and second free layer parts, whereby the magnetization of said second free layer part orients the magnetization of said first free layer part in an opposite direction thereto.

3 more elements

Dependencies are inferred from the claim text.