Memory cells having ferroelectric materials
Memory cells having ferroelectric materials and methods of operating and forming the same are described herein. As an example, a memory cell can include a first electrode and a second electrode, and an ion source and a ferroelectric material formed between the first electrode and the second electrode, where the ferroelectric material serves to stabilize storage of ions transitioned from the ion source.
1. A memory cell, comprising:
a first electrode and a second electrode; and
an ion source and a tunnel barrier comprising a ferroelectric material formed between the first electrode and the second electrode,
wherein the ferroelectric material serves to stabilize storage in the ferroelectric material of ions transitioned from the ion source.
2. The memory cell of claim 1 , wherein the tunnel barrier further comprises a non-ferroelectric tunnel oxide material formed as at least part of the ferroelectric material, wherein the ferroelectric material serves to stabilize storage of ions transitioned from the ion source to the non-ferroelectric tunnel oxide material.
3. The memory cell of claim 1 , wherein the ferroelectric material is formed in contact with and between the ion source and the second electrode.
4. The memory cell of claim 1 , wherein the ions are oxygen ions.
5. The memory cell of claim 1 , wherein the ion source comprises a mixed valence oxide formed in contact with and between the ferroelectric material and the first electrode.
6. The memory cell of claim 1 , wherein ferroelectric material is a gate dielectric.
7. The memory cell of claim 1 , wherein the ferroelectric material is an insulating metal oxide.
8. A memory array, comprising:
a first number of conductive lines;
a second number of conductive lines intersecting the first number of conductive lines; and
a memory cell formed between a first electrode and a second electrode at each of a number of intersections of the first number of conductive lines and the second number of conductive lines, wherein the memory cell comprises a material stack including at least one mixed valence oxide material formed in direct contact with a ferroelectric insulating metal oxide material.
9. The array of claim 8 , wherein the at least one mixed valence oxide material is selected from a group that includes a perovskite metal oxide (PMO), a lanthanum strontium manganese oxide (LaSrMnOx), a lanthanum strontium copper oxide (LaSrCuOx), a lanthanum strontium cobalt oxide (LaSrCoOx), a lanthanum calcium manganese oxide (LaCaMnOx), a lanthanum copper oxide (LaCuOx), a lanthanum cobalt oxide (LaCoOx), a lanthanum nickelate oxide (LaNiOx), a strontium titanate oxide (SrTiOx), a strontium copper oxide (SrCuOx), a strontium cobalt oxide (SrCoOx), a praseodymium calcium manganese oxide (PrCaMnOx), a praseodymium manganese oxide (PrMnOx), and a titanium oxide (TiOx).
10. The array of claim 8 , wherein the ferroelectric insulating metal oxide material is at least one orthorhombic ferroelectric material selected from a group that includes a hafnium oxide (HfOx), a hafnium silicon oxide (HfSiOx), a hafnium aluminum oxide (HfAlOx), a zirconium hafnium oxide (ZrHfOx), and a zirconium magnesium oxide (ZrMgOx).
11. The array of claim 8 , wherein the ferroelectric insulating metal oxide material comprises a charge dipole that stabilizes storage of ions transitioned to the non-ferroelectric tunnel oxide material.
12. A method of forming a memory cell, comprising:
forming a first electrode;
forming an oxygen source material that is in contact with the first electrode;
forming a ferroelectric material that is in direct contact with the oxygen source material; and
forming a second electrode that is in contact with the ferroelectric material.
13. The method of claim 12 , wherein forming the oxygen source material comprises forming at least one mixed valence oxide material.
14. The method of claim 12 , wherein forming the oxygen source material comprises forming the oxygen source material using atomic layer deposition.
15. The method of claim 12 , wherein forming the oxygen source material comprises forming the oxygen source material using chemical vapor deposition.
16. The method of claim 12 , wherein forming the ferroelectric material comprises forming an orthorhombic ferroelectric material.
17. The method of claim 16 , wherein forming the orthorhombic ferroelectric material comprises forming hafnium silicon oxide.
18. The method of claim 12 , wherein forming the ferroelectric material comprises forming the ferroelectric material using atomic layer deposition.
19. The method of claim 12 , wherein forming the ferroelectric material comprises forming the ferroelectric material using chemical vapor deposition.
20. A method of operating a memory cell, comprising:
applying a voltage across a material stack formed between a first electrode and a second electrode to transition a number of ionic species from an oxygen source material to a ferroelectric insulating metal oxide material in the material stack; and
wherein the number of ionic species transitioned to the ferroelectric insulating metal oxide material is stabilized between poles of a dipole of the ferroelectric insulating metal oxide material.
21. The method of claim 20 , wherein a number of oxygen ions are transitioned from a mixed valence oxide source material to the ferroelectric insulating metal oxide material.
22. The method of claim 20 , wherein transitioning the number of ionic species from the source material to the ferroelectric insulating metal oxide material that forms at least a part of a tunnel oxide material comprises changing a resistance of the memory cell.
23. The method of claim 20 , wherein the number of ionic species in the ferroelectric insulating metal oxide material is stabilized by the dipole of the ferroelectric insulating metal oxide material having a charge polarity adjacent the oxygen source material that is a charge polarity of the ionic species.
24. The method of claim 20 , wherein a charge polarity of the dipole of the ferroelectric insulating metal oxide material is adjusted prior to the memory cell being programmed by applying the voltage across the material stack.