Acoustic transducer with gap-controlling geometry and method of manufacturing an acoustic transducer

• US 10,284,960 B2
• Filed: 05/01/2015
• Issued: 05/07/2019
• Est. Priority Date: 03/31/2011
• Status: Active Grant

• Current Assignee: Qualcomm Technologies Incorporated (Qualcomm, Inc.)
• Original Assignee: Vesper Technologies Inc.
• Inventors: Grosh, Karl, Littrell, Robert J.
• Primary Examiner(s): Dougherty, Thomas M
• Application Number:
  US14/702,319
• Publication Number:
  US 20150271606A1
• Time in Patent Office: 1,467 Days
• Field of Search: 310311, 310328, 310330-333, 310348, 310365, 310366
• CPC Class Codes: H04R 17/02 Microphones
• CPC Class Codes: H04R 17/025 using a piezoelectric polymer
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005
• CPC Class Codes: H04R 2410/03 Reduction of intrinsic noise in microphones
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182
• CPC Class Codes: H04R 31/003 for diaphragms or their outer suspension
• CPC Class Codes: H04R 7/06 comprising a plurality of sections or layers
• CPC Class Codes: H10N 30/05 Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
• CPC Class Codes: H10N 30/074 by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
• CPC Class Codes: H10N 30/082 by etching, e.g. lithography

Abstract

A transducer of the preferred embodiment including a transducer and a plurality of adjacent, tapered cantilevered beams. Each of the beams define a beam base, a beam tip, and a beam body disposed between the beam base and the beam tip. The beams are arranged such that each of the beam tips extends toward a common area. Each beam is joined to the substrate along the beam base and is free from the substrate along the beam body. A preferred method of manufacturing a transducer can include: depositing alternating layers of piezoelectric and electrode onto the substrate in block, processing the deposited layers to define cantilever geometry in block, depositing metal traces in block, and releasing the cantilevered beams from the substrate in block.

Claims

1. A transducer comprising:

a substrate having an edge that defines a central void region in the substrate;

a plurality of adjacent, tapered cantilevered beams, each of the plurality of adjacent, tapered cantilevered beams comprising;

at least one stiff piezoelectric layer;

a first electrode layer supported on a top surface of the at least one stiff piezoelectric layer; and

a second electrode layer supported on a bottom surface of the at least one stiff piezoelectric layer; and

each of the tapered cantilevered beams defined by a beam base, a beam tip, and a beam body disposed between the beam base and the beam tip, with each of the beam tips extending towards a common area, with each tapered cantilevered beam joined to the edge of the substrate along the beam base through a portion of the at least one stiff piezoelectric layer adjacent to the edge of the substrate or a portion of the second electrode layer adjacent to the edge of the substrate, and with each of the tapered cantilevered beams being free from the substrate along the beam body and beam tip.

2. The transducer of claim 1, wherein a gap defined along the length of adjacent, tapered cantilevered beams is approximately 1 micron or less.

3. The transducer of claim 1, wherein the common area is an imaginary point, wherein the beam tips substantially converge at the imaginary point.

4. The transducer of claim 1, wherein the beam bases form a substantially continuous microphone perimeter.

5. The transducer of claim 4, wherein each tapered cantilevered beam comprises a triangle, such that the microphone perimeter comprises a substantially polygonal perimeter.

6. The transducer of claim 1, wherein each of the at least one stiff piezoelectric layer extends substantially through a width and a length of a tapered, cantilevered beam.

7. The transducer of claim 1, wherein at least two of the tapered cantilevered beams are electrically coupled together in series.

8. The transducer of claim 1, wherein each tapered cantilevered beam comprises alternating piezoelectric and electrode layers.

9. The transducer of claim 1, wherein each of the tapered cantilevered beams includes two piezoelectric layers and three electrode layers.

10. The transducer of claim 1, wherein the electrode layers of each tapered cantilevered beam are electrically coupled in series by metal traces.

11. The transducer of claim 1, wherein the at least one stiff piezoelectric layer comprises aluminum nitride, and the first and second electrode layers each comprise molybdenum.

12. The transducer of claim 1, wherein the transducer is a MEMS transducer.

13. The transducer of claim 1, wherein the transducer is a sensor or an acoustic sensor.

14. A sensor comprising:

a substrate having an edge that defines a central void region in the substrate;

a plurality of tapered cantilevered beams, each of the plurality of adjacent, tapered cantilevered beams comprising;

at least one stiff piezoelectric layer;

a first electrode layer supported on a top surface of the at least one stiff piezoelectric layer; and

a second electrode layer supported on a bottom surface of the at least one stiff piezoelectric layer; and

each of the tapered cantilevered beams defined by a base fixed to the substrate and each tapered cantilevered beam tapering from the base into a movable tip, the plurality of tapered cantilevered beams arranged adjacently with each movable tip converging in a common area such that the bases form a substantially continuous microphone perimeter; and

with each tapered cantilevered beam joined to the edge of the substrate along the beam base through a portion of the at least one stiff piezoelectric layer adjacent to the edge of the substrate or a portion of the second electrode adjacent to the edge of the substrate.

15. The sensor of claim 14, wherein the sensor is an acoustic sensor.

16. The sensor of claim 14, wherein a gap defined along the length of adjacent, tapered cantilevered beams is approximately 1 micron or less.

17. A transducer comprising:

a substrate; and

a plurality of adjacent, tapered cantilevered beams each comprising first and second electrode layers spaced by a dielectric layer, each defining a beam base, a beam tip, and a beam body disposed between the beam base and the beam tip, arranged such that each beam tip extends to but does not touch at a common point, and further such that each tapered cantilevered beam is joined to the substrate along the beam base and each beam body is unattached to the substrate along the beam body and beam tip.

18. The transducer of claim 17, wherein the transducer is a MEMS transducer, a sensor or an acoustic sensor and each tapered cantilevered beam is joined to the substrate along the beam base through the corresponding dielectric layer of the cantilevered beam.

19. The transducer of claim 17, wherein gaps between each of adjacent tapered cantilevered beams define a gap-controlling geometry being approximately 1 micron or less with the gaps through the dielectric layer and the first electrode layer and the second electrode layer and along lengths of the adjacent, tapered cantilevered beams.

20. The transducer of claim 17, wherein each beam comprises:

at least one piezoelectric layer;

a first electrode layer supported on a top surface of the at least one piezoelectric layer; and

a second electrode layer supported on a bottom surface of the at least one piezoelectric layer; and

wherein each of the at least one piezoelectric layer extends substantially through a width and a length of a tapered, cantilevered beam.