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US 5,949,707 AGranted
Giant magnetoresistive effect memory cell
AssigneeNonvolatile Electronics, Incorporated
InventorsArthur V. Pohm, Brenda A. Everitt
Life of this patent
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Abstract
A digital data memory having a bit structure in a memory cell based on an intermediate separating material with two major surfaces having thereon a magnetoresistive, anisotropic ferromagnetic thin-film of differing thicknesses. These bit structures are fabricated within structural extent limits to operate satisfactorily, and are fabricated as series connected members of storage line structures. A corresponding conductive word line structure adjacent corresponding ones of these memory cells is used for selecting or operating them, or both, in data storage and retrieval operations.
Claims45
A magnetoresistive, ferromagnetic thin-film based digital memory, said memory comprising:
- a first storage line structure having a first storage line pair of end terminal regions suited to conduct electrical current in at least one direction therethrough, said storage line end terminal regions having electrically connected therebetween at least one bit structure, each said bit structure comprising:
- an intermediate layer, said intermediate layer having two major surfaces on opposite sides thereof such that said major surfaces are separated by less than 50 .ANG.;
- and
- a memory film of a magnetoresistive, anisotropic ferromagnetic material less than 100 .ANG. thick on each of said intermediate layer major surfaces of substantially matching composition but of thicknesses differing from one another outwardly from those surfaces by at least 5% to thereby primarily provide switching thresholds for magnetizations of said film adjacent each of said intermediate layer major surfaces that differ in value for a switching of these magnetizations from both being directed initially in substantially a common direction to being directed in substantially opposite directions versus a switching from being directed initially in substantially opposite directions to both being directed in substantially a common direction;
- and
- a word line structure having a pair of word line end terminal regions adapted to conduct electrical current in at least one direction therethrough, said pair of word line end terminal regions having an electrical conductor electrically connected therebetween which is located across an electrical insulating layer from said memory film on one of said major surfaces of said intermediate layer of a corresponding said bit structure.
3 more elements
A magnetoresistive, ferromagnetic thin-film based digital memory, said memory comprising:
- a first storage line structure having a first storage line pair of end terminal regions suited to conduct electrical current in at least one direction therethrough, said storage line end terminal regions having electrically connected therebetween at least one bit structure, each said bit structure comprising:
- an intermediate layer, said intermediate layer having two major surfaces on opposite sides thereof such that said major surfaces are separated by less than 50 .ANG.;
- and
- a memory film of a magnetoresistive, anisotropic ferromagnetic material less than 100 .ANG. thick on each of said intermediate layer major surfaces of thicknesses differing from one another outwardly from those surfaces sufficiently greatly, for a selected current being conducted through said bit structure, to prevent magnetizations of said memory film adjacent those surfaces, oriented initially in a direction substantially opposite that of a word line magnetic field generated in a word line field direction by a current supplied in a word line conductor adjacent thereto as a result of a relatively rapid change in current magnitude initiated in said adjacent word line conductor, from both pointing in said word line field direction as a result of such a said current magnitude change initiation which would otherwise occur absent said thickness difference even though that magnitude of said word line magnetic field, resulting after expiration of transients therein following such a said current change initiation, is less than that switching threshold magnitude characterizing said thicker memory film if switched by a word line magnetic field resulting from a relatively slowly changing current in said adjacent word line conductor;
- and
- a word line structure having a pair of word line end terminal regions adapted to conduct electrical current in at least one direction therethrough, said pair of word line end terminal regions having an electrical conductor electrically connected therebetween which is located across an electrical insulating layer from said memory film on one of said major surfaces of said intermediate layer of a corresponding said bit structure as said adjacent word line conductor therefor.
3 more elements
A magnetoresistive, ferromagnetic thin-film based digital memory, said memory comprising:
- a first storage line structure having a first storage line pair of end terminal regions suited to conduct electrical current in at least one direction therethrough, said storage line end terminal regions having electrically connected therebetween at least one bit structure having a length and a width substantially perpendicular thereto that is smaller in extent than said length, each said bit structure comprising:
- an intermediate layer, said intermediate layer having two major surfaces on opposite sides thereof such that said major surfaces are separated by less than 50 .ANG.;
- and
- a memory film of a magnetoresistive, anisotropic ferromagnetic material less than 100 .ANG. thick on each of said intermediate layer major surfaces of thicknesses differing from one another outwardly from those surfaces by at least 5%, said memory film in a said bit structure being characterized by an anisotropy field, and said width being sufficiently small that demagnetization fields arising in said memory film in response to its saturation magnetization being oriented along that said width exceed in magnitude said anisotropy field;
- and
- a word line structure having a pair of word line end terminal regions adapted to conduct electrical current in at least one direction therethrough, said pair of word line end terminal regions having an electrical conductor electrically connected therebetween which is located across an electrical insulating layer from said memory film on one of said major surfaces of said intermediate layer of a corresponding said bit structure.
3 more elements
Dependencies are inferred from the claim text.