PIEZOELECTRIC MICROMACHINED ULTRASONIC TRANSDUCER (PMUT)

• US 20170322290A1
• Filed: 07/08/2016
• Published: 11/09/2017
• Est. Priority Date: 05/04/2016
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: NG, Eldwin, TSAI, Julius Ming-Lin, APTE, Nikhil
• Granted Patent: US 10,656,255 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: A61B 8/4483 characterised by features of the ultrasound transducer
• CPC Class Codes: B06B 1/0622 on one surface
• CPC Class Codes: B06B 1/0688 with foil-type piezoelectric elements, e.g. PVDF
• CPC Class Codes: G01S 15/89 for mapping or imaging
• CPC Class Codes: G01S 7/521 Constructional features
• CPC Class Codes: H10N 30/2047 Membrane type
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals

Abstract

A Piezoelectric Micromachined Ultrasonic Transducer (PMUT) device is provided. The PMUT includes a substrate and an edge support structure connected to the substrate. A membrane is connected to the edge support structure such that a cavity is defined between the membrane and the substrate, where the membrane is configured to allow movement at ultrasonic frequencies. The membrane includes a piezoelectric layer and first and second electrodes coupled to opposing sides of the piezoelectric layer. An interior support structure is disposed within the cavity and connected to the substrate and the membrane.

Claims

1. A Piezoelectric Micromachined Ultrasonic Transducer (PMUT) device comprising:

a substrate;

an edge support structure connected to the substrate;

a membrane connected to the edge support structure such that a cavity is defined between the membrane and the substrate, the membrane configured to allow movement at ultrasonic frequencies, the membrane comprising;

a piezoelectric layer; and

first and second electrodes coupled to opposing sides of the piezoelectric layer; and

an interior support structure disposed within the cavity and connected to the substrate and the membrane.

2. The PMUT device of claim 1, further comprising:

a second interior support structure disposed within the cavity and connected to the substrate and the membrane.

3. The PMUT device of claim 1, wherein the interior support structure contacts the edge support structure.

4. The PMUT device of claim 1, wherein the interior support structure is non-centrally positioned within the cavity.

5. The PMUT device of claim 1, wherein the first electrode defines a continuous layer.

6. The PMUT device of claim 1, wherein the first electrode is a patterned layer.

7. The PMUT device of claim 1, the membrane further comprising:

a mechanical support layer connected to the first electrode.

8. The PMUT device of claim 7, wherein the mechanical support layer defines a continuous layer.

9. The PMUT device of claim 7, wherein the mechanical support layer is a patterned layer.

10. The PMUT device of claim 1, wherein the piezoelectric layer defines a continuous layer.

11. The PMUT device of claim 1, wherein the piezoelectric layer is a patterned layer.

12. The PMUT device of claim 1, wherein the second electrode extends into the cavity and defines an area between the edge support structure and the interior support structure.

13. The PMUT device of claim 1, wherein the interior support structure is connected to the piezoelectric layer of the membrane.

14. The PMUT device of claim 1, wherein the PMUT device is substantially circular such that the edge support structure and the membrane are substantially circular.

15. The PMUT device of claim 1, wherein the PMUT device is substantially square-shaped such that the edge support structure and the membrane are substantially square-shaped.

16. The PMUT device of claim 1, wherein at least one of the first electrode and the second electrode is electrically coupled through the interior support structure.

17. The PMUT device of claim 1, the membrane further comprising:

a third electrode coupled to the piezoelectric layer on an opposing side of the piezoelectric layer as the first electrode.

18. The PMUT device of claim 1, wherein the edge support structure is connected to an electric potential.

19. The PMUT device of claim 1, wherein the substrate comprises a CMOS logic wafer.

20. A Piezoelectric Micromachined Ultrasonic Transducer (PMUT) array comprising:

a plurality of PMUT devices, wherein at least one PMUT device of the plurality of PMUT devices comprises;

a substrate;

an edge support structure connected to the substrate, wherein the edge support structure is connected to an electric potential;

a membrane connected to the edge support structure such that a cavity is defined between the membrane and the substrate, the membrane configured to allow movement at ultrasonic frequencies, the membrane comprising;

a piezoelectric layer;

first and second electrodes coupled to opposing sides of the piezoelectric layer; and

a mechanical support layer connected to the first electrode; and

an interior support structure disposed within the cavity and connected to the substrate and the membrane.

21. The PMUT array of claim 20, wherein the at least one PMUT device of the plurality of PMUT devices further comprises:

a second interior support structure disposed within the cavity and connected to the substrate and the membrane.

22. The PMUT array of claim 20, wherein the interior support structure contacts the edge support structure.

23. The PMUT array of claim 20, wherein the interior support structure is non-centrally positioned within the cavity.

24. The PMUT array of claim 20, wherein the second electrode extends into the cavity and defines an area between the edge support structure and the interior support structure.

25. The PMUT array of claim 20, wherein the interior support structure is connected to the piezoelectric layer of the membrane.

26. The PMUT array of claim 20, wherein at least one of the first electrode and the second electrode is electrically coupled through the interior support structure.

27. The PMUT array of claim 20, wherein the substrate comprises a CMOS logic wafer.

28. The PMUT array of claim 20, wherein adjacent PMUT devices of the plurality of PMUT devices are electrically isolated.

29. The PMUT array of claim 20, wherein groups of adjacent PMUT devices of the plurality of PMUT devices are electrically connected, and wherein adjacent groups of adjacent PMUT devices are electrically isolated.

30. An image sensing system comprising:

a plurality of Piezoelectric Micromachined Ultrasonic Transducer (PMUT) devices, wherein at least one PMUT device of the plurality of PMUT devices comprises;

a substrate;

an edge support structure connected to the substrate;

a membrane connected to the edge support structure such that a cavity is defined between the membrane and the substrate, the membrane configured to allow movement at ultrasonic frequencies, the membrane comprising;

a piezoelectric layer;

first and second electrodes coupled to opposing sides of the piezoelectric layer; and

a mechanical support layer connected to the first electrode; and

an interior support structure disposed within the cavity and connected to the substrate and the membrane; and

control logic electrically coupled to the plurality of PMUT devices, the control logic for sensing an image.

31. The image sensing system of claim 30, wherein the second electrode extends into the cavity and defines an area between the edge support structure and the interior support structure.

32. The image sensing system of claim 31, wherein at least one of the first electrode and the second electrode is electrically coupled through the interior support structure.