Magnetoresistive random access memory with reduced switching field variation
View Patent ↗An array of multi-state, multi-layer magnetic memory devices ( 10 ) wherein each memory device comprises a nonmagnetic spacer region ( 22 ) and a free magnetic region ( 24 ) positioned adjacent to a surface of the nonmagnetic spacer region, the free magnetic region including a plurality of magnetic layers ( 36,34,38 ), wherein the magnetic layer ( 36 ) in the plurality of magnetic layers positioned adjacent to the surface of the nonmagnetic spacer region has a thickness substantially greater than a thickness of each of the magnetic layers ( 34,38 ) subsequently grown thereon wherein the thickness is chosen to improve the magnetic switching variation so that the magnetic switching field for each memory device in the array of memory devices is more uniform.
1. A multi-state, multi-layer magnetic memory device, comprising:
a nonmagnetic spacer region with a surface; and
a free magnetic region positioned adjacent to the surface of the nonmagnetic spacer region, the free magnetic region including:
a first magnetic layers having a first thickness; and
a second magnetic layer positioned adjacent to the nonmagnetic spacer region, the second magnetic layer having a second thickness that is greater than about 40 Å and also greater than the first thickness.
2. A device as claimed in claim 1 wherein the second magnetic layer is an amorphous magnetic alloy.
3. A device as claimed in claim 1 wherein the free magnetic region includes an anti-ferromagnetic coupling spacer layer.
4. A device as claimed in claim 3 wherein the anti-ferromagnetic coupling spacer material includes at least one of copper (Cu), silver (Ag), gold (Au), chromium (Cr), ruthenium (Ru), rhenium (Re), osmium (Os), titanium (Ti), Rhodium (Rh), platinum (Pt), palladium (Pd), and alloys thereof.
5. A device as claimed in claim 1 wherein the free magnetic region includes at least one of nickel (Ni), iron (Fe), cobalt (Co), manganese (Mn), combinations thereof, and alloys thereof.
6. A device as claimed in claim 1 wherein the free magnetic region includes a synthetic anti-ferromagnetic material region including N ferromagnetic layers which are anti-ferromagnetically coupled where N is a whole number greater than or equal to two.
7. A device as claimed in claim 6 wherein each of the N ferromagnetic layers is anti-ferromagnetically coupled by sandwiching a layer of an anti-ferromagnetic coupling material between each adjacent ferromagnetic layer in the N ferromagnetic layers.
8. A device as claimed in claim 1 wherein a fixed magnetic region is positioned adjacent to a second surface of the nonmagnetic spacer region.
9. A device as claimed in claim 1 wherein the nonmagnetic spacer region includes at least one of aluminum oxide (AlC), aluminum nitride (AlN), silicon oxide (SiO).
10. A device as claimed in claim 1 wherein the nonmagnetic spacer is a conductive material including at least one of copper (Cu), chromium (Cr), silver (Ag), and gold (Au).
11. A device as claimed in claim 6 wherein one of the N ferromagnetic layers of the synthetic anti-ferromagnetic material region that is positioned adjacent to the surface of the nonmagnetic spacer is at least as thick as any of the other N ferromagnetic layers which comprise the synthetic anti-ferromagnetic material region.
12. A device as claimed in claim 1 wherein the second thickness is less than approximately 120 Å.