Patent ID: 7230844
Filing Date: 2007-06-12
Classification: G11C,H01L

Abstract:
1. A ferromagnetic thin-film based digital memory, said memory comprising: a substrate; a plurality of bit structures, each supported on said substrate and separated from one another by spacer material therebetween, that are electrically interconnected with information storage and retrieval circuitry, said bit structures each comprising first and second relatively fixed magnetization layers each with a magnetization direction substantially opposite one another and formed of materials selected from only ferromagnetic and antiferromagnetic materials, and a ferromagnetic material film in which a characteristic magnetic property is substantially maintained below a first critical temperature above which such magnetic property is not maintained, and with said ferromagnetic material film being separated from said first relatively fixed magnetization layer by a first intermediate layer of a nonmagnetic material having first and second major surfaces and further being separated from said second relatively fixed magnetization layer by a second intermediate layer of a nonmagnetic material having first and second major surfaces with said nonmagnetic material of one of said first and second intermediate layers being electrically insulative and that one remaining being electrically conductive, said bit structures each having a first interconnection structure providing electrical contact thereto positioned against a first contact surface thereof substantially parallel to said major surfaces of said first and second intermediate layers and also between said first contact surface and said substrate; and a plurality of word line structures each having a pair of word line end terminal regions adapted to conduct electrical current in at least one direction therethrough, each of said pairs of word line end terminal regions having an electrical conductor electrically connected therebetween which is located on an opposite side of said first and second intermediate layers of a corresponding one of said bit structures from said first interconnection structure providing electrical contact thereto, said information storage and retrieval circuitry for drawing electrical current selectively through each said bit structure and said first interconnection structure providing electrical contact thereto to raise temperatures of said ferromagnetic material film therein while being above temperatures of at least an adjacent said bit structure because of sufficient extent of, and smallness of thermal conductivities of, at least portions of said selected bit structure and of those portions of said substrate and said spacer material positioned thereabout.