Ferroelectric material, MEMS component comprising a ferroelectric material, MEMS device comprising a first MEMS component, method of producing a MEMS component, and method of producing a CMOS-compatible MEMS component

Patent metadata

Field	Value
Publication number	US-11744158-B2
Application number	US-202017016941-A
Country	US
Kind code	B2
Filing date	Sep 10, 2020
Priority date	Mar 13, 2018
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

A ferroelectric material includes a mixed crystal having AlN and at least one nitride of a transition metal. The proportion of the nitride of the transition metal is selected such that a direction of an initial or spontaneous polarity of the ferroelectric material is switchable by applying a switchover voltage. The switchover voltage is below a breakdown voltage of the ferroelectric material.

First claim

The invention claimed is:

1. Ferroelectric material; comprising
a mixed crystal comprising AlN and at least one nitride of a transition metal;
wherein the proportion of the nitride of the transition metal is selected such that a direction of an initial or spontaneous polarity of the ferroelectric material is switchable by applying a switchover voltage, the switchover voltage being below a breakdown voltage of the ferroelectric material.

2. Ferroelectric material as claimed in claim 1 , the ferroelectric material comprising a mechanical stress that lies between a first value of a compressive stress and a second value of a tensile stress, wherein an absolute value of the first value is lower than an absolute value of the second value.

3. Ferroelectric material as claimed in claim 2 , wherein the mechanical stress lies within an interval of −600 MPa to 2000 MPa, wherein negative values represent compressive stress and positive values represent tensile stress.

4. Ferroelectric material as claimed in claim 1 , wherein the direction of polarity of the ferroelectric material is maintained after removal of the applied switchover voltage.

5. Ferroelectric material as claimed in claim 1 , wherein the ratio of a number of transition metal atoms to a sum of the number of transition metal atoms and a number of aluminum atoms ranges between greater than or equal to 0.2 and less than or equal to 0.5.

6. Ferroelectric material as claimed in claim 1 , wherein the transition metal comprises scandium, yttrium, titanium, niobium and/or chromium.

7. Method comprising:
providing a mixed crystal exhibiting an initial or spontaneous polarity, wherein the mixed crystal comprises AlN and at least one nitride of a transition metal,
wherein the proportion of the nitride of the transition metal is selected such that a direction of the initial or spontaneous polarity of the ferroelectric material is switchable by applying a switchover voltage, the switchover voltage being below a breakdown voltage of the ferroelectric material; and
applying a switchover voltage to the mixed crystal, so that the direction of the initial or spontaneous polarity of the mixed crystal is reversed.

8. MEMS component comprising a ferroelectric material as claimed in claim 1 .

9. MEMS component as claimed in claim 8 , comprising
a first ferroelectric layer comprising the ferroelectric material,
a first electrode disposed on a first surface of the first ferroelectric layer, and
a second electrode disposed on a second surface of the first ferroelectric layer, the second surface being opposite the first surface.

10. MEMS component as claimed in claim 9 , comprising
a second ferroelectric layer disposed on the first electrode opposite the first ferroelectric layer, and
a third electrode disposed on a first surface of the second ferroelectric layer, the first surface of the second ferroelectric layer being disposed to face away from the first electrode.

11. MEMS component as claimed in claim 10 , wherein the first electrode comprises a first electrode layer and a second electrode layer, and
wherein an insulating layer in which a neutral plane lies is disposed between the first and second electrode layers.

12. MEMS component as claimed in claim 10 , wherein the first electrode comprises a first electrode layer and a second electrode layer, and
wherein a passive layer in which a neutral plane lies is disposed between the first and second electrode layers.

13. MEMS component as claimed in claim 10 , comprising
a third ferroelectric layer disposed at the third electrode, opposite the second ferroelectric layer,
a fourth electrode disposed on a first surface of the third ferroelectric layer, the first surface of the third ferroelectric layer being disposed to face away from the third electrode,
a fourth ferroelectric layer disposed on the second electrode, opposite the first ferroelectric layer, and
a fifth electrode disposed on a first surface of the fourth ferroelectric layer to face away from the second electrode.

14. MEMS component as claimed in claim 9 , comprising a passive layer disposed on the second electrode.

15. MEMS component as claimed in claim 12 , wherein the passive layer is connected to a substrate at least on one side.

16. MEMS component as claimed in claim 8 , wherein the MEMS component comprises a multilayer MEMS actuator, a multilayer MEMS sensor or a multilayer MEMS generator.

17. MEMS device, comprising
a substrate, and
a first MEMS component as claimed in claim 12 , wherein the passive layer of the MEMS component is deflectably disposed on the substrate.

18. MEMS device as claimed in claim 16 , comprising
a second MEMS component as claimed in claim 12 , wherein the first and second passive layers are a community, and the electrodes and ferroelectric layers of the first and second MEMS components are arranged in parallel.

Assignees

• Fraunhofer Ges Forschung
• Univ Kiel Christian Albrechts

Inventors

• Wagner Bernhard
• Lofink Fabian
• Kaden Dirk
• Fichtner Simon

Classifications

• H10N30/704

  based on piezoelectric or electrostrictive films or coatings · CPC title

• H10N30/853 Primary

  Ceramic compositions · CPC title

• B81B7/02

  containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] (B81B7/04 takes precedence) · CPC title

• H10N30/045

  by polarising · CPC title

• H10N30/1051

  Electricity · mapped topic