FERROELECTRIC THIN FILMS

• US 20100252901A1
• Filed: 06/16/2010
• Published: 10/07/2010
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Original Assignee: Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Inventors: Rappe, Andrew Marshall, Kolpak, Alexie Michelle, Sai, Na
• Granted Patent: US 8,022,454 B2
• Time in Patent Office: Days
• US Class Current: 257/421
• CPC Class Codes: H01G 4/10 Metal-oxide dielectrics H01G4/085 takes precedence
• CPC Class Codes: H01G 4/228 Terminals
• CPC Class Codes: H01G 4/33 Thin- or thick-film capacitors thin- or thick-film circuits H01L27/00; capacitors without a potential-jump or surface barrier specially adapted for integrated circuits, details thereof, multistep manufacturing processes therefor H01L28/40
• CPC Class Codes: H01G 7/06 having a dielectric selected for the variation of its permittivity with applied voltage, i.e. ferroelectric capacitors electrets H01G7/02
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

Ferroelectric structures and methods of making the structures are presented. The ferroelectric structures can include an electrode in contact with a ferroelectric thin film. The contact can be arranged so that a portion of the atoms of the ferroelectric thin film are in contact with at least a portion of the atoms of the electrode. The electrode can be made of metal, a metal alloy, or a semiconducting material. A second electrode can be used and placed in contact with the ferroelectric thin film. Methods of making and using the ferroelectric structures are also presented.

Claims

1. A ferroelectric structure, comprising:

a first electrode comprising a first layer having a periodic atomic arrangement;

a ferroelectric thin film comprising a first termination and a second termination;

wherein at least a portion of the first layer of the first electrode is in epitaxial contact with at least a portion of the first termination of the ferroelectric thin film; and

wherein the first termination of the ferroelectric thin film has a periodic atomic arrangement that approximately matches the periodic atomic arrangement of the first layer of the first electrode.

2. The ferroelectric structure of claim 1, further comprising:

a second electrode comprising a first layer having a periodic atomic arrangement;

wherein at least a portion of the first layer of the second electrode is in contact with at least a portion of the second termination of the ferroelectric thin film; and

wherein the second termination of the ferroelectric thin film has a periodic atomic arrangement that approximately matches the periodic atomic arrangement of the first layer of the second electrode.

3. The ferroelectric structure of claim 2, wherein the first electrode and second electrode comprise metal or a metal alloy.

4. The ferroelectric structure of claim 3, wherein the ferroelectric thin film has a thickness of approximately 4 Angstroms.

5. The ferroelectric structure of claim 3, wherein the ferroelectric thin film is a perovskite thin film.

6. A charge storage device comprising the ferroelectric structure of claim 1.

7. A FERAM device comprising the ferroelectric structure of claim 1.

8. A ferroelectric structure, comprising:

a first electrode comprising a first surface, the first surface having a periodic arrangement of atoms of the first electrode;

a ferroelectric thin film comprising a first termination and a second termination;

wherein the first termination is formed of a periodic arrangement of at least one type of atom of the ferroelectric thin film; and

wherein at least a portion of the periodic arrangement of atoms of the first surface of the first electrode is in epitaxial contact with at least a portion of the periodic arrangement of atoms of the first termination of the ferroelectric thin film.

9. The ferroelectric structure of claim 8, further comprising:

a second electrode comprising a first surface, the first surface having a periodic arrangement of atoms of the second electrode;

wherein the second termination is formed of a periodic arrangement of at least one type of atom of the ferroelectric thin film; and

wherein at least a portion of the periodic arrangement of atoms of the first surface of the second electrode is in epitaxial contact with at least a portion of the periodic arrangement of atoms of the second termination of the ferroelectric thin film.

10. The ferroelectric structure of claim 9, wherein the first electrode and second electrode comprise metal or a metal alloy.

11. The ferroelectric structure of claim 10, wherein the ferroelectric thin film has a thickness of approximately 4 Angstroms.

12. The ferroelectric structure of claim 10, wherein the ferroelectric thin film is a perovskite thin film.

13. A charge storage device comprising the ferroelectric structure of claim 8.

14. A FERAM device comprising the ferroelectric structure of claim 8.

15. A method of forming a ferroelectric structure, comprising:

forming a ferroelectric thin film comprising a first termination and a second termination, and wherein the first termination has a periodic arrangement of atoms of the ferroelectric thin film;

forming a first electrode comprising a first surface having a periodic arrangement of atoms of the first electrode;

wherein at least a portion of the periodic arrangement of atoms of the first surface of the first electrode is formed in epitaxial contact with at least a portion of the periodic arrangement of atoms of the first termination of the ferroelectric thin film.

16. The method of claim 15, further comprising:

forming a second electrode comprising a first surface having a periodic arrangement of atoms of the first electrode;

wherein the second termination has a periodic arrangement of atoms of the ferroelectric thin film; and

wherein at least a portion of the periodic arrangement of atoms of the first surface of the second electrode is formed in epitaxial contact with at least a portion of the periodic arrangement of atoms of the second termination of the ferroelectric thin film.

17. The method of claim 16, further comprising forming the first electrode of a metal or metal alloy.

18. The method of claim 17, further comprising forming the second electrode of a metal of a metal alloy.

19. The method of claim 18, further comprising forming the second electrode of platinum.

20. The method of claim 15, wherein forming the ferroelectric thin film comprises forming a perovskite thin film.

21. A method of increasing polarization of a ferroelectric material above a bulk value, comprising:

providing a ferroelectric material having a bulk polarization value;

forming a ferroelectric thin film of the ferroelectric material, the ferroelectric thin film having a first termination and a second termination;

providing a first electrode having a first surface;

providing a second electrode having a first surface;

placing the first surface of the first electrode in epitaxial contact with the first termination; and

placing the first surface of the second electrode in epitaxial contact with the second termination.