Giant magnetoresistive effect memory cell

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:
• a plurality of intermediate layers in a succession thereof, each said intermediate layer in said plurality thereof having two major surfaces on opposite sides thereof such that said major surfaces are separated by less than 50 .ANG.;
• and
• a plurality of memory films of a magnetoresistive, anisotropic ferromagnetic material less than 100 .ANG. thick with there being one of said memory films in said plurality thereof between each pair of successive said intermediate layers and one adjacent each of those outer said end major surfaces of those said intermediate layers positioned at opposite ends of said succession thereof, a said memory film in said plurality thereof being of a thickness greater than that of all others in said plurality thereof by at least 5% to thereby primarily provide switching thresholds for magnetizations of said memory films of said plurality thereof that differ for said thicker memory film from those of other memory films remaining in said plurality thereof, 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 air 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.

A magnetoresistive, ferromagnetic thin-film based digital memory structure having a length and a width substantially perpendicular thereto that is smaller in extent than said length, said memory structure comprising:

• a plurality of intermediate layers in a succession thereof, each said intermediate layer in said plurality thereof having two major surfaces on opposite sides thereof such that said major surfaces are separated by less than 50 .ANG.;
• and
• a plurality of memory films of a magnetoresistive, anisotropic ferromagnetic material less than 100 .ANG. thick with there being one of said memory films in said plurality thereof between each pair of successive said intermediate layers and one adjacent each of those outer said end major surfaces of those said intermediate layers positioned at opposite ends of said succession thereof, a said memory film in said plurality thereof being of a thickness greater than that of all others in said plurality thereof, (a) said length of said memory structure, and (b) that ratio of volume of said thicker memory film to those combined volumes those of other memory films remaining in said plurality thereof and (c) compositions of said memory films all being selected to provide said structure with two stable magnetization states, absent externally supplied magnetic fields, for said direction of magnetization of said thicker memory film remaining substantially unchanged.