MRAM device fabricated using chemical mechanical polishing
View Patent ↗The present invention provides a method of forming an MRAM cell which minimizes the occurrence of electrical shorts during fabrication. A first conductor is provided in a trench in an insulating layer and an upper surface of the insulating layer and the first conductor is planarized. Then, a first dielectric layer is deposited over the first conductor and insulating layer to a thickness at least greater than the thickness of a desired MRAM cell. The first dielectric layer is then patterned and etched to form an opening over the first conductor for the cell shapes. Then, the magnetic layers comprising the MRAM cell are consecutively formed within the cell shapes and the first dielectric layer.
1. A memory circuit, said memory circuit comprising:
a plurality of memory cells, each memory cell comprising:
a first magnetic layer adjacent a conductive layer, said first magnetic layer comprising a first plurality of films;
a nonmagnetic tunnel barrier layer separated from said conductive layer by said first magnetic layer; and
a second magnetic layer separated from said first magnetic layer by said nonmagnetic tunnel barrier layer, said second magnetic layer comprising:
a second plurality of films including a ferromagnetic material adjacent said nonmagnetic tunnel barrier layer, a tantalum film adjacent said ferromagnetic material, and;
a chemical mechanical polishing stop arranged to protect said second magnetic layer, wherein said chemical mechanical polishing stop is an oxide.
2. A magnetic random access memory cell, said memory cell comprising:
a first magnetic layer adjacent a conductive layer, said first magnetic layer comprising a first plurality of films;
a nonmagnetic tunnel barrier layer separated from said conductive layer by said first magnetic layer; and
a second magnetic layer separated from said first magnetic layer by said nonmagnetic tunnel barrier layer, said second magnetic layer comprising:
a second plurality of films including a ferromagnetic material adjacent said nonmagnetic tunnel barrier layer, a tantalum film adjacent said ferromagnetic material; and
a chemical mechanical polishing stop arranged to protect said second magnetic layer, wherein said chemical mechanical polishing stop is a nitride.
3. A magnetic random access memory cell, said memory cell comprising:
a first magnetic layer adjacent a conductive layer, said first magnetic layer comprising a first plurality of films;
a nonmagnetic tunnel barrier layer separated from said conductive layer by said first magnetic layer; and
a second magnetic layer separated from said first magnetic layer by said nonmagnetic tunnel barrier layer, said second magnetic layer comprising:
a second plurality of films including a ferromagnetic material adjacent said nonmagnetic tunnel barrier layer, a tantalum film adjacent said ferromagnetic material, and;
a chemical mechanical polishing stop arranged to protect said second magnetic layer, wherein said chemical mechanical polishing stop is an oxide.
4. The memory cell of claim 3 , wherein said first magnetic layer is a pinned layer.
5. The memory cell of claim 4 , wherein said first magnetic layer is arranged and configured to provide a ferromagnetic pinned layer.
6. The memory cell of claim 3 , wherein said second magnetic layer includes a sense layer.
7. The memory cell of claim 6 , wherein said sense layer is arranged and configured to provide a ferromagnetic sense layer.
8. The memory cell of claim 3 , wherein said nonmagnetic tunnel barrier layer comprises aluminum oxide.
9. The memory cell of claim 8 , wherein said aluminum oxide has a thickness of about 5 to 25 Angstroms.
10. The memory cell of claim 3 , wherein said nonmagnetic tunnel barrier layer comprises a material selected from the group consisting of copper, titanium oxide, magnesium oxide, silicon oxide and aluminum nitride.
11. The memory cell of claim 3 , wherein said conductive layer is selected from the group consisting of copper, aluminum, tungsten and gold.
12. The memory cell of claim 3 , wherein said first magnetic layer comprises a first tantalum layer, a first nickel-iron layer, a manganese-iron layer, and a second nickel-iron layer.
13. The memory cell of claim 12 , wherein said plurality of films comprises a third nickel-iron layer, a second tantalum layer, and a tungsten nitrogen chemical mechanical polishing stop.
14. The memory cell of claim 3 , wherein said memory cell is coupled to at least one word line.
15. A processor system comprising at least one memory circuit, wherein said at least one memory circuit comprises at least one memory cell according to claim 3 .