Imaging devices having piezoelectric transceivers

Patent metadata

Field	Value
Publication number	US-10648852-B2
Application number	US-201815951121-A
Country	US
Kind code	B2
Filing date	Apr 11, 2018
Priority date	Apr 11, 2018
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

A micromachined ultrasonic transducer (MUT). The MUT includes: a substrate; a membrane suspending from the substrate; a bottom electrode disposed on the membrane; a piezoelectric layer disposed on the bottom electrode and an asymmetric top electrode is disposed on the piezoelectric layer. The areal density distribution of the asymmetric electrode along an axis has a plurality of local maxima, wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency is located.

First claim

What is claimed is:

1. A micromachined ultrasonic transducer (MUT), comprising: an electrode that is symmetric with respect to a first axis and asymmetric with respect to a second axis that is normal to the first axis, the first axis extending along a direction where the electrode has a longest dimension, the second axis passing through a midpoint between two ends of the electrode on the first axis, wherein an areal density distribution of the electrode along an axis has a plurality of local maxima, and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.

2. The MUT of claim 1 , wherein the MUT is a capacitive micromachined ultrasound transducer (cMUT).

3. The MUT of claim 1 , wherein the MUT is a piezoelectric micromachined ultrasound transducer (pMUT).

4. The MUT of claim 3 , further comprising:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane; and
a piezoelectric layer disposed on the bottom electrode;
wherein the electrode is disposed on the piezoelectric layer.

5. The MUT of claim 4 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AIN, ZnO, PVDF, and LiNiO 3 .

6. A micromachined ultrasonic transducer (MUT), comprising:
a symmetric electrode,
wherein an areal density distribution of the symmetric electrode along an axis has a plurality of local maxima and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.

7. The MUT of claim 6 , wherein the axis extends along a direction where the symmetric electrode has a longest dimension.

8. The MUT of claim 6 , wherein the vibrational resonance frequency has a symmetric vibrational mode.

9. The MUT of claim 6 , wherein the MUT is a capacitive micromachined ultrasound transducer (cMUT).

10. The MUT of claim 6 , wherein the MUT is a piezoelectric micromachined ultrasound transducer (pMUT).

11. The MUT of claim 10 , further comprising:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane;
a piezoelectric layer disposed on the bottom electrode; and
a top electrode disposed on the piezoelectric layer, wherein the top electrode is the symmetric electrode.

12. The MUT of claim 11 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AIN, ZnO, PVDF, and LiNiO 3 .

13. An imaging device, comprising:
a transducer array including a plurality of micromachined ultrasonic transducers (MUTs),
each of the plurality of MUTs comprising:
an electrode that is symmetric with respect to a first axis and asymmetric with respect to a second axis that is normal to the first axis, the first axis extending along a direction where the electrode has a longest dimension, the second axis passing through a midpoint between two ends of the electrode on the first axis, wherein an areal density distribution of the electrode along an axis has a plurality of local maxima, and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.

14. The imaging device of claim 13 , wherein each of the plurality of MUTs is a capacitive micromachined ultrasound transducer (cMUT).

15. The imaging device of claim 13 , wherein each of the plurality of MUTs is a piezoelectric micromachined ultrasound transducer (pMUT).

16. The imaging device of claim 15 , wherein each of the plurality of MUTs further comprises:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane; and
a piezoelectric layer disposed on the bottom electrode,
wherein the electrode is disposed on the piezoelectric layer.

17. The imaging device of claim 15 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AlN, ZnO, PVDF, and LiNiO 3 .

18. An imaging device, comprising:
a transducer array including a plurality of micromachined ultrasonic transducers (MUTs),
each of the plurality of MUTs comprising:
a symmetric electrode,
wherein an areal density distribution of the symmetric electrode along an axis has a plurality of local maxima and wherein locations of the plurality of local maxima coincide with locations where a plurality of anti-nodal points at a vibrational resonance frequency are located.

19. The imaging device of claim 18 , wherein the vibrational resonance frequency has a symmetric vibrational mode.

20. The imaging device of claim 18 , wherein each of the plurality of MUTs is a capacitive micromachined ultrasound transducer (cMUT).

21. The imaging device of claim 18 , wherein each of the plurality of MUTs is a piezoelectric micromachined ultrasound transducer (pMUT).

22. The imaging device of claim 21 , wherein each of the plurality of MUTs further comprises:
a substrate;
a membrane suspending from the substrate;
a bottom electrode disposed on the membrane;
a piezoelectric layer disposed on the bottom electrode; and
a top electrode disposed on the piezoelectric layer,
wherein the top electrode is the symmetric electrode.

23. The imaging device of claim 21 , wherein the piezoelectric layer is formed of at least one of PZT, KNN, PZT-N, PMN—Pt, AIN, Sc—AIN, ZnO, PVDF, and LiNiO 3 .

Assignees

• Exo Imaging Inc

Inventors

• Akkaraju Sandeep
• Kwon Haesung
• Bircumshaw Brian

Classifications

• G01S7/5208 Primary

  with integration of processing functions inside probe or scanhead · CPC title

• B81B3/0021

  Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00) · CPC title

• G01N29/07

  by measuring propagation velocity or propagation time of acoustic waves · CPC title

• B06B1/0292 Primary

  Electrostatic transducers, e.g. electret-type · CPC title

• G01H11/08 Primary

  using piezoelectric devices · CPC title