MEMS vibrating structure using a single-crystal piezoelectric thin-film layer having domain inversions

• US 7,898,158 B1
• Filed: 11/03/2008
• Issued: 03/01/2011
• Est. Priority Date: 11/01/2007
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Lee, Seungbae, Li, Sheng-Shian, Bhattacharjee, Kushal
• Primary Examiner(s): SanMartin; J.
• Application Number:
  US12/263,883
• Time in Patent Office: 848 Days
• Field of Search: 310/351, 310320-321
• US Class Current: 310/351
• CPC Class Codes: H03H 2009/241 Bulk-mode MEMS resonators
• CPC Class Codes: H03H 9/02228 Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer
• CPC Class Codes: H03H 9/02275 Comb electrodes
• CPC Class Codes: H03H 9/2405 of microelectro-mechanical resonators

Abstract

The present invention relates to a micro-electro-mechanical systems (MEMS) vibrating structure supported by a MEMS anchor system, and includes a single-crystal piezoelectric thin-film layer having domain inversions, which determine certain vibrational characteristics of the MEMS vibrating structure. The MEMS vibrating structure may have dominant lateral vibrations or dominant thickness vibrations. The single-crystal piezoelectric thin-film layer may include Lithium Tantalate or Lithium Niobate, and may provide MEMS vibrating structures with precise sizes and shapes, which may provide high accuracy and enable fabrication of multiple resonators having different resonant frequencies on a single substrate.

Claims

1. A vibrating micro-electro-mechanical circuit comprising:

a substrate having a substrate surface;

at least one anchor on the substrate surface; and

a micro-electro-mechanical systems (MEMS) vibrating structure comprising;

a body suspended from the at least one anchor and comprising a single-crystal piezoelectric thin-film having a plurality of domains comprising a nominal domain adjacent to an inverted domain, such that the nominal domain has a first plurality of dipoles substantially oriented in a nominal orientation and the inverted domain has a second plurality of dipoles substantially oriented in an inverted orientation, wherein the inverted orientation is translated about 180 degrees from the nominal orientation; and

a first conducting section residing on a first surface of the body that is about parallel to the substrate surface.

2. The vibrating micro-electro-mechanical circuit of claim 1 wherein the MEMS vibrating structure further comprises a second conducting section residing on a second surface of the body that is about parallel to the substrate surface, such that the MEMS vibrating structure has dominant vibrations when a first electrical signal is applied to the first conducting section and the second conducting section.

3. The vibrating micro-electro-mechanical circuit of claim 2 wherein the dominant vibrations are dominant lateral vibrations that are about parallel to the substrate surface.

4. The vibrating micro-electro-mechanical circuit of claim 2 wherein the dominant vibrations are dominant thickness vibrations that are about perpendicular to the substrate surface.

5. The vibrating micro-electro-mechanical circuit of claim 2 wherein the dominant vibrations comprise dominant lateral vibrations that are about parallel to the substrate surface and dominant thickness vibrations that are about perpendicular to the substrate surface.

6. The vibrating micro-electro-mechanical circuit of claim 2 wherein the single-crystal piezoelectric thin-film provides the dominant vibrations.

7. The vibrating micro-electro-mechanical circuit of claim 6 wherein the dominant vibrations are based on a direction of a cut of growth of the single-crystal piezoelectric thin-film.

8. The vibrating micro-electro-mechanical circuit of claim 2 wherein the second conducting section provides the dominant vibrations and comprises a conducting resonating material.

9. The vibrating micro-electro-mechanical circuit of claim 8 wherein the conducting resonating material comprises at least one of highly-doped Silicon, polysilicon, isotropic material, and other conductive material.

10. The vibrating micro-electro-mechanical circuit of claim 2 wherein the single-crystal piezoelectric thin-film and the second conducting section provide the dominant vibrations.

11. The vibrating micro-electro-mechanical circuit of claim 2 wherein:

the second conducting section comprises a third surface that is about parallel to the substrate surface; and

the MEMS vibrating structure further comprises a supplemental resonating section residing on the third surface of the second conducting section.

12. The vibrating micro-electro-mechanical circuit of claim 11 wherein the supplemental resonating section comprises supplemental resonating material.

13. The vibrating micro-electro-mechanical circuit of claim 12 wherein the supplemental resonating material provides the dominant vibrations.

14. The vibrating micro-electro-mechanical circuit of claim 13 wherein the supplemental resonating material and the single-crystal piezoelectric thin-film provide the dominant vibrations.

15. The vibrating micro-electro-mechanical circuit of claim 14 wherein the supplemental resonating material is a single-crystal material.

16. The vibrating micro-electro-mechanical circuit of claim 2 wherein the MEMS vibrating structure further comprises a third conducting section residing on the first surface of the body, such that the MEMS vibrating structure has the dominant vibrations when the first electrical signal is applied to the first conducting section and the second conducting section, and a second electrical signal is applied to the second conducting section and the third conducting section.

17. The vibrating micro-electro-mechanical circuit of claim 1 wherein the plurality of domains comprises nominal domains that alternate with inverted domains along a plane that is about parallel to the substrate surface.

18. The vibrating micro-electro-mechanical circuit of claim 17 wherein the nominal domains alternate with the inverted domains in only one direction.

19. The vibrating micro-electro-mechanical circuit of claim 17 wherein the nominal domains alternate with the inverted domains in only two directions.

20. The vibrating micro-electro-mechanical circuit of claim 17 wherein the nominal domains alternate with the inverted domains around a perimeter of the body.

21. The vibrating micro-electro-mechanical circuit of claim 17 wherein the nominal domains and the inverted domains are formed by poling.

22. The vibrating micro-electro-mechanical circuit of claim 21 wherein the poling uses an electric field.

23. The vibrating micro-electro-mechanical circuit of claim 22 wherein the electric field has a nominal poling orientation when poling the nominal domains and an inverted poling orientation when poling the inverted domains, wherein the inverted poling orientation is translated about 180 degrees from the nominal poling orientation.

24. The vibrating micro-electro-mechanical circuit of claim 23 wherein the nominal orientation is not parallel to the nominal poling orientation and the inverted orientation is not parallel to the inverted poling orientation.

25. The vibrating micro-electro-mechanical circuit of claim 17 wherein the nominal domains and the inverted domains are periodically-poled.

26. The vibrating micro-electro-mechanical circuit of claim 17 wherein the nominal domains and the inverted domains are non-periodically-poled.

27. The vibrating micro-electro-mechanical circuit of claim 17 wherein each of the nominal domains has a nominal domain length and a nominal domain width that is constant along the nominal domain length, and the each of the inverted domains has an inverted domain length and an inverted domain width that is constant along the inverted domain length.

28. The vibrating micro-electro-mechanical circuit of claim 17 wherein each of the nominal domains has a nominal domain length and a nominal domain width that is not constant along the nominal domain length, and the each of the inverted domains has an inverted domain length and an inverted domain width that is not constant along the inverted domain length.

29. The vibrating micro-electro-mechanical circuit of claim 17 wherein the nominal domains and the inverted domains form a checkerboard pattern.

30. The vibrating micro-electro-mechanical circuit of claim 17 wherein each of the inverted domains is adjacent to at least one of the nominal domains.

31. The vibrating micro-electro-mechanical circuit of claim 1 further comprising:

a first mechanical support member between one of the at least one anchor and the MEMS vibrating structure; and

a second mechanical support member between another of the at least one anchor and the MEMS vibrating structure.

32. The vibrating micro-electro-mechanical circuit of claim 1 wherein the single-crystal piezoelectric thin-film comprises Lithium Tantalate.

33. The vibrating micro-electro-mechanical circuit of claim 1 wherein the single-crystal piezoelectric thin-film comprises Lithium Niobate.

34. A vibrating micro-electro-mechanical circuit comprising:

a substrate having a substrate surface;

at least one anchor on the substrate surface; and

a micro-electro-mechanical systems (MEMS) vibrating structure comprising;

a body suspended from the at least one anchor and comprising a single-crystal piezoelectric thin-film having a plurality of domains comprising a nominal domain adjacent to an inverted domain, such that the nominal domain has a first plurality of dipoles substantially oriented in a nominal orientation and the inverted domain has a second plurality of dipoles substantially oriented in an inverted orientation, wherein the inverted orientation is translated about 180 degrees from the nominal orientation;

a first conducting section residing on a first surface of the body that is about parallel to the substrate surface; and

a second conducting section residing on the first surface of the body, such that the MEMS vibrating structure has dominant vibrations when a first electrical signal is applied to the first conducting section and the second conducting section,

wherein the body has a second surface that is about parallel to the substrate surface and approximately no material resides on the second surface.