Magnetic memory cell including two-terminal selector device
The present invention is directed to a memory cell that includes a magnetic tunnel junction (MTJ) memory element and a two-terminal selector element coupled in series. The MTJ memory element includes a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween. The magnetic reference layer structure includes one or more magnetic reference layers having a first invariable magnetization direction substantially perpendicular to layer planes thereof. The two-terminal selector element includes a first inert electrode and a second inert electrode with a volatile switching layer interposed therebetween; a first active electrode formed adjacent to the first inert electrode; and a second active electrode formed adjacent to the second inert electrode. The volatile switching layer includes a plurality of metal-rich particles or clusters embedded in a matrix or at least one conductor layer interleaved with insulating layers.
1. A memory cell comprising:
a magnetic tunnel junction (MTJ) memory element including a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween, said magnetic free layer structure including one or more magnetic free layers having a variable magnetization direction substantially perpendicular to layer planes thereof, said magnetic reference layer structure including one or more magnetic reference layers having a first invariable magnetization direction substantially perpendicular to layer planes thereof; and
a two-terminal selector element coupled to said MTJ memory element in series, said two-terminal selector element including:
a first electrode and a second electrode with a volatile switching layer interposed therebetween, said volatile switching layer including a plurality of metal-rich particles or clusters embedded in an insulating matrix;
a third electrode formed adjacent to said first electrode opposite said volatile switching layer; and
a fourth electrode formed adjacent to said second electrode opposite said volatile switching layer.
2. The memory cell of claim 1 , wherein said insulating matrix is made of an oxide.
3. The memory cell of claim 1 , wherein said insulating matrix comprises hafnium and oxygen.
4. The memory cell of claim 1 , wherein said first and second electrodes are inert electrodes.
5. The memory cell of claim 1 , wherein said first and second electrodes are made of titanium nitride.
6. The memory cell of claim 1 , wherein said first and second electrodes are made of a same conductive material selected from the group consisting of tantalum nitride, titanium silicide, nickel silicide, cobalt silicide, and any combinations thereof.
7. The memory cell of claim 1 , wherein said third and fourth electrodes are active electrodes.
8. The memory cell of claim 1 , wherein said first and second electrodes are inert electrodes, and said third and fourth electrodes are active electrodes.
9. The memory cell of claim 1 , wherein said plurality of metal-rich particles or clusters and said third and fourth electrodes are made of a same material.
10. The memory cell of claim 1 , wherein said plurality of metal-rich particles or clusters and said third and fourth electrodes are made of silver.
11. The memory cell of claim 1 , wherein said plurality of metal-rich particles or clusters and said third and fourth electrodes are made of a same material selected from the group consisting of copper, cobalt, nickel, and any combinations thereof.
12. The memory cell of claim 1 , wherein said two-terminal selector element further includes a fifth electrode formed adjacent to said third electrode opposite said first electrode and a sixth electrode formed adjacent to said fourth electrode opposite said second electrode.
13. The memory cell of claim 12 , wherein said fifth and sixth electrodes are inert electrodes.
14. The memory cell of claim 12 , wherein said fifth electrode is made of iridium, ruthenium, or platinum, said sixth electrode is made of iridium, ruthenium, or platinum.
15. The memory cell of claim 1 , wherein said MTJ memory element further includes a magnetic fixed layer structure exchanged coupled to said magnetic reference layer structure through an anti-ferromagnetic coupling layer, said magnetic fixed layer structure having a second invariable magnetization direction that is substantially perpendicular to a layer plane thereof and is opposite to said first invariable magnetization direction.