Piezoelectric microphone fabricated on glass

• US 8,724,832 B2
• Filed: 08/30/2011
• Issued: 05/13/2014
• Est. Priority Date: 08/30/2011
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Stephanou, Philip Jason, Burns, David William
• Primary Examiner(s): Le, Huyen D
• Application Number:
  US13/221,791
• Publication Number:
  US 20130051587A1
• Time in Patent Office: 987 Days
• Field of Search: 381/114, 381/173, 381/174, 381/175, 381/69, 381/190, 381/369, 381/191, 310/311, 310/320, 310/322, 29/253.5, 257/254, 257/416, 257/417
• US Class Current: 381/173
• CPC Class Codes: G01H 11/08 using piezoelectric devices
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: H04R 1/222 for microphones H04R1/24, H04R1/26 take precedence
• CPC Class Codes: H04R 17/02 Microphones
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 2201/003 Mems transducers or their use of the electrostatic type H04R19/005
• CPC Class Codes: H04R 23/02 Transducers using more than one principle simultaneously
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 2499/15 Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops
• 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 7/24 Tensioning by means acting directly on free portions of diaphragm or cone
• CPC Class Codes: H10N 30/80 Constructional details
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

This disclosure provides systems, methods and apparatus for sense elements in an electromechanical microphone device. In one aspect, a piezoelectric sense element may include a glass substrate, electrode layers, piezoelectric layers, and elastic layers. The elastic layers may serve to modify the neutral plane of the piezoelectric sense element. Including an elastic layer or layers to modify the neutral plane of the piezoelectric sense element may serve to configure the sense element such that the piezoelectric layer generates a voltage in response to a sound wave or may serve to increase the sensitivity of the sense element.

Claims

1. An apparatus for detecting sound comprising:

a glass substrate;

a first electrode layer, the first electrode layer having a first portion disposed on the glass substrate and a second portion suspended over the glass substrate;

a first piezoelectric layer disposed on the first electrode layer;

a second electrode layer disposed on the first piezoelectric layer;

a second piezoelectric layer disposed on the second electrode layer;

a third electrode layer disposed on the second piezoelectric layer; and

an elastic layer disposed on at least a portion of the third electrode layer;

wherein the second portion of the first electrode layer is configured to generate a first strain in the first piezoelectric layer and a second strain in the second piezoelectric layer.

2. The apparatus of claim 1, wherein the elastic layer modifies a neutral plane of the first electrode layer, the first piezoelectric layer, the second electrode layer, the second piezoelectric layer, and the third electrode layer.

3. The apparatus of claim 1, wherein the elastic layer includes at least one of silicon nitride, silicon oxynitride, silicon oxide, silicon, aluminum nitride, a metal, and a polymer.

4. The apparatus of claim 1, wherein at least one of a thickness of the first piezoelectric layer or a thickness of the second piezoelectric layer is about 0.25 to 5 micrometers.

5. The apparatus of claim 1, wherein at least one of a thickness of the first electrode layer, a thickness of the second electrode layer, or a thickness of the third electrode layer is about 50 to 300 nanometers.

6. The apparatus of claim 1, wherein at least one of the first piezoelectric layer and the second piezoelectric layer includes aluminum nitride.

7. The apparatus of claim 1, wherein the first electrode layer, the second electrode layer, or the third electrode layer include at least one of copper, platinum, molybdenum, tungsten, ruthenium, gold, and aluminum.

8. The apparatus of claim 1, wherein the second portion of the first electrode layer includes a member configured to interact with a sound wave.

9. The apparatus of claim 1, further comprising:

a display;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

10. The apparatus of claim 9, further comprising:

a driver circuit configured to send at least one signal to the display; and

a controller configured to send at least a portion of the image data to the driver circuit.

11. The apparatus of claim 9, further comprising:

an image source module configured to send the image data to the processor.

12. The apparatus of claim 11, wherein the image source module includes at least one of a receiver, transceiver, and transmitter.

13. The apparatus of claim 9, further comprising:

an input device configured to receive input data and to communicate the input data to the processor.

14. An apparatus for detecting sound comprising:

a glass substrate;

a first electrode layer, the first electrode layer having a first portion attached to the glass substrate and a second portion detached from the glass substrate;

a first piezoelectric layer disposed on the first electrode layer;

a second electrode layer disposed on the first piezoelectric layer;

an elastic layer disposed on the second electrode layer;

a third electrode layer disposed on the elastic layer;

a second piezoelectric layer disposed on the third electrode layer; and

a fourth electrode layer disposed on the second piezoelectric layer;

wherein the second portion of the first electrode layer is configured to generate a first strain in the first piezoelectric layer and a second strain in the second piezoelectric layer.

15. The apparatus of claim 14, wherein the elastic layer modifies a neutral plane of the first electrode layer, the first piezoelectric layer, the second electrode layer, the third electrode layer, the second piezoelectric layer, and the fourth electrode layer.

16. The apparatus of claim 14, wherein the second portion of the first electrode layer includes a member configured to interact with a sound wave.

17. An apparatus comprising:

a glass substrate;

a first electrode layer disposed on the glass substrate;

a second electrode layer, the second electrode layer having a first portion disposed on the glass substrate and a second portion suspended over the first electrode layer and the glass substrate;

a piezoelectric layer disposed on the second electrode layer;

a third electrode layer disposed on the piezoelectric layer; and

an elastic layer disposed on at least a portion of the third electrode layer;

wherein the second portion of the second electrode layer is configured to generate a strain in the piezoelectric layer and to vary a distance between the second electrode layer and the first electrode layer.

18. The apparatus of claim 17, wherein the elastic layer modifies a neutral plane of the second electrode layer, the first piezoelectric layer, and the third electrode layer.

19. The apparatus of claim 17, wherein the second portion of the second electrode layer includes a member configured to interact with a sound wave.

20. The apparatus of claim 17, wherein the second electrode layer and the first electrode layer are configured to generate a capacitive signal in response to variation of the distance between the second electrode layer and the first electrode layer.

21. The apparatus of claim 17, wherein the distance between the second electrode layer and the first electrode layer is configured to be varied by a bias voltage applied between the second electrode layer and the first electrode layer.

22. A method of forming an acoustic microphone comprising:

forming a sacrificial layer on a glass substrate;

forming a first electrode layer on the sacrificial layer and on the glass substrate;

forming a first piezoelectric layer on the first electrode layer;

forming a second electrode layer on the first piezoelectric layer;

forming a second piezoelectric layer on the second electrode layer;

forming a third electrode layer on the second piezoelectric layer;

forming an elastic layer on at least a portion of the third electrode layer; and

removing the sacrificial layer such that a first portion of the first electrode layer remains on the glass substrate and a second portion of the first electrode layer is suspended over the glass substrate, wherein the second portion of the first electrode layer is capable of generating a first strain in the first piezoelectric layer and a second strain in the second piezoelectric layer.

23. The method of claim 22, wherein the second portion of the first electrode layer includes a member configured to interact with a sound wave to induce the strain in the first piezoelectric layer.

24. The method of claim 22, wherein the elastic layer modifies a neutral plane of the first electrode layer, the first piezoelectric layer, the second electrode layer, the second piezoelectric layer, and the third electrode layer.