CN111579493B

CN111579493B - Acoustic sensor based on optical detection

Info

Publication number: CN111579493B
Application number: CN202010425125.4A
Authority: CN
Inventors: 康晓旭; 沈若曦
Original assignee: Shanghai IC R&D Center Co Ltd
Current assignee: Shanghai IC R&D Center Co Ltd
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2023-06-02
Anticipated expiration: 2040-05-19
Also published as: CN111579493A

Abstract

The invention discloses an acoustic sensor based on optical detection, which comprises: the two chips are bonded, the chips comprise a first vibrating membrane arranged on the front surface of the substrate, the first vibrating membrane comprises an optical waveguide device, a first cavity is arranged on the back surface of the substrate, and the bottom of the first cavity reaches the lower surface of the first vibrating membrane; the two chips are bonded by the back surface of the substrate, and a closed cavity is formed between the first vibrating membranes; the two first vibrating membranes absorb sound waves to generate different deformation, so that the optical transmission distance of light in the two optical waveguide devices is changed differently, the transmission time difference or the transmission phase difference of the light in the two optical waveguide devices is changed correspondingly, the deformation degree of the two first vibrating membranes is detected, the strength of acoustic signals is sensed, and the detection sensitivity and the response speed of the sensor are improved.

Description

Acoustic sensor based on optical detection

Technical Field

The invention relates to the technical field of semiconductor integrated circuits and sensors, in particular to an acoustic sensor based on optical detection.

Background

Conventional acoustic detection devices typically use resistance and capacitance changes to detect, which have problems of slow speed and low sensitivity.

Disclosure of Invention

The object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to provide an acoustic sensor based on optical detection.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

an acoustic sensor based on optical detection, comprising: two chips bonded to each other, the chips comprising:

a substrate;

a first diaphragm provided on a front surface of the substrate, the first diaphragm containing an optical waveguide device;

the bottom of the first cavity reaches the lower surface of the first vibrating membrane;

bonding the two chips with the back surfaces of the substrates, and forming a closed cavity consisting of two first cavities between the first vibrating membranes;

the two first vibrating films absorb sound waves to generate different deformation amounts, so that the optical transmission distance of light in the two optical waveguide devices is changed differently, the transmission time difference or the transmission phase difference of the light in the two optical waveguide devices is changed correspondingly, the deformation degree of the two first vibrating films is detected, and the intensity of an acoustic signal is sensed.

Further, the two first diaphragms have pre-deformation amounts that are convexly curved toward each other.

Further, the optical waveguide device is provided with a waveguide channel, the waveguide channel is spiral, and the light receiving end and the light emitting end are respectively arranged at two ends of the waveguide channel outside the spiral.

Further, the waveguide channel is surrounded by a dielectric layer.

Further, the waveguide channel material comprises silicon.

Further, a fixed electrode is further arranged on the first vibrating membrane.

Further, a vibrating electrode is also suspended above the fixed electrode.

Further, a plurality of sound holes for conducting sound waves are distributed on the fixed electrode and the vibrating electrode.

Further, a supporting layer is arranged between the fixed electrode and the vibrating electrode, and a resonant cavity is formed between the fixed electrode and the vibrating electrode.

Further, the fixed electrode and the vibrating electrode are in a flat state.

According to the technical scheme, the optical waveguide device is integrated on the vibration device (the fixed electrode and the vibration electrode) of the traditional acoustic detector, when the vibration device vibrates, the optical waveguide device is stretched, so that the light transmission distance is prolonged or the phase is changed, the light emitting device is arranged on one side of the optical waveguide device, and the light receiving device such as TOF (time of flight) is arranged on the other side of the optical waveguide device, so that the acoustic vibration can be induced by utilizing the optical detection means such as the change of the light transmission distance or the change of the phase, and the detection sensitivity and the response speed of the sensor are improved.

Drawings

FIG. 1 is a schematic diagram of an acoustic sensor based on optical detection according to a preferred embodiment of the present invention.

Fig. 2 is a schematic view of an optical waveguide device according to a preferred embodiment of the present invention.

Detailed Description

The following describes the embodiments of the present invention in further detail with reference to the accompanying drawings.

In the following detailed description of the embodiments of the present invention, the structures of the present invention are not drawn to a general scale, and the structures in the drawings are partially enlarged, deformed, and simplified, so that the present invention should not be construed as being limited thereto.

In the following detailed description of the present invention, please refer to fig. 1, fig. 1 is a schematic diagram of an acoustic sensor based on optical detection according to a preferred embodiment of the present invention. As shown in fig. 1, an acoustic sensor based on optical detection of the present invention comprises two

chips

10, 20 back-bonded together.

Please refer to fig. 1. The two

chips

10 and 20 have a plurality of structures which are identical and symmetrically arranged, and the two

chips

10 and 20 comprise: a

substrate

11, 21 and a

first diaphragm

12, 22 provided on the front surface of the

substrate

11, 21.

The

substrates

11 and 21 may be commonly used semiconductor substrates, such as silicon substrates. The

first diaphragms

12 and 22 contain optical waveguide devices 13 and 23.

A

first cavity

19, 29 is provided on the back side of each

substrate

11, 21, the bottom of the

first cavity

19, 29 reaching the lower surface of the

first diaphragm

12, 22, respectively, i.e. the

first diaphragm

12, 22 is in fact suspended from the

first cavity

19, 29.

The two

chips

10, 20 are bonded with the back surfaces of the

respective substrates

11, 21 and the respective

first cavities

19, 29 are aligned so that a larger closed

cavity

19 and 29 consisting of the two

first cavities

19, 29 is formed between the respective

first diaphragms

12, 22. Wherein, the upper and lower ends of the closed

cavities

19 and 29 are respectively provided with a first vibrating

membrane

12 and 22, and the side walls of the closed

cavities

19 and 29 are surrounded by the

substrates

11 and 21 of the two

chips

10 and 20 respectively.

Thus, when one of the

first diaphragms

12 or 22 is faced to the direction of the sound source (for example, assuming that the sound source is located above the illustrated sensor device), the two

first diaphragms

12, 22 will each absorb sound waves and generate a certain amount of deformation.

The two

first diaphragms

12, 22 may be respectively deformed by a predetermined amount, for example, the two

first diaphragms

12, 22 may be deformed by an amount protruding toward each other, that is, bent toward the inside of the closed

cavities

19 and 29. When the two

first diaphragms

12, 22 each absorb sound waves, one first diaphragm 12 located above the drawing will produce a larger bending deformation with respect to the pre-deformation toward the inside of the closed

cavities

19 and 29, while the other first diaphragm 22 located below the drawing will produce a compression under pressure toward the lower outer side of the closed

cavities

19 and 29, producing a smaller bending deformation with respect to the pre-deformation.

Therefore, the optical transmission distance of the light in the two optical waveguide devices 13, 23 can be changed differently by utilizing the different deformation amounts generated when the two

first diaphragms

12, 22 each absorb the acoustic wave, so that the transmission time difference or the transmission phase difference of the light in the two optical waveguide devices 13, 23 is changed correspondingly, and the intensity of the acoustic signal can be perceived by detecting the deformation degree of the two

first diaphragms

12, 22.

Please refer to fig. 2 in combination with fig. 1. The optical waveguide devices 13, 23 may have

waveguide channels

131, 231 provided therein; the

waveguide channels

131, 231 may be of a spiral structure, the optical waveguide devices 13, 23 are provided with light receiving ends and light emitting ends, and the light receiving ends and the light emitting ends are respectively provided on both ends of the

waveguide channels

131, 231 outside the spiral structure. When a light emitting device is provided at the light emitting end of the light waveguide device 13, 23 and a light receiving device such as a TOF (time of flight) is provided at the light receiving end, acoustic vibrations can be induced by using optical detection means such as a change in optical transmission distance or a change in phase, thereby improving the detection sensitivity and response speed of the sensor.

As an alternative embodiment, the

waveguide channels

131, 231 may be formed of, for example, a silicon material, but is not limited thereto. The

waveguide channels

131 and 231 may be surrounded by the

dielectric layers

14 and 24 around the

waveguide channels

131 and 231, so that the waveguide channels 131 and 231 (optical waveguide devices 13 and 23) and the surrounding

dielectric layers

14 and 24 together form the main structure of the

first diaphragms

12 and 22, as shown in fig. 1.

Please refer to fig. 1. As a preferred embodiment, a capacitive structure may also be provided on the

first diaphragm

12, 22. For example, one

fixed electrode

17, 27 may be provided on each side of the

first diaphragm

12, 22, i.e. the

fixed electrode

17, 27 is provided on the

dielectric layer

14, 24 of the

first diaphragm

12, 22 and is spaced apart from the

waveguide channel

131, 231. At the same time, a vibrating

electrode

16, 26 can also be suspended above the fixed

electrode

17, 27.

Support layers

15, 25 are arranged between the

fixed electrodes

17, 27 and the vibrating

electrodes

16, 26, the vibrating

electrodes

16, 26 arranged in a suspended manner are supported by the

support layers

15, 25, and a

resonant cavity

18, 28 is formed between the

support layers

15, 25, the

fixed electrodes

17, 27 and the vibrating

electrodes

16, 26. The

resonant cavities

18, 28 may be formed by a conventional release process. In this way, a capacitor structure composed of the

fixed electrodes

17, 27, the

vibrating electrodes

16, 26, and the

resonators

18, 28 is formed on the upper and lower sides of the two

first diaphragms

12, 22, respectively.

A plurality of sound holes for conducting sound waves are distributed over the

stationary electrodes

17, 27 and the vibrating

electrodes

16, 26 to ensure that acoustic signals are transmitted to the

first diaphragms

12, 22. The

first diaphragms

12, 22 may be made of a metal material.

The two capacitor structures can be made flat on the

first diaphragms

12 and 22, that is, the

fixed electrodes

17 and 27 and the vibrating

electrodes

16 and 26 can be made flat by stress adjustment at the time of manufacture. At the same time, a voltage can be applied to the

fixed electrodes

17, 27 and the vibrating

electrodes

16, 26 by means of a capacitive design, so that the two

first diaphragms

12, 22 located inside the two capacitive structures are pre-bent to some extent towards the inside of the closed

cavities

19 and 29. When the acoustic wave causes the upper and lower

first diaphragms

12, 22 to deform, the deformation thereof causes the two optical waveguide devices 13, 23 to be in a stretched and compressed state, respectively, and by detecting the difference signal intensity, a differential signal can be obtained, so that the intensity of the acoustic signal can be judged.

The foregoing description is only of the preferred embodiments of the present invention, and the embodiments are not intended to limit the scope of the invention, so that all the equivalent structural changes made in the description and drawings of the present invention are included in the scope of the invention.

Claims

1. An acoustic sensor based on optical detection, comprising: two chips bonded to each other, the chips comprising:

a substrate;

the bottom of the first cavity reaches the lower surface of the first vibrating membrane, and the optical waveguide device is suspended on the first cavity;

and the two first vibrating films are utilized to absorb sound waves to generate different deformation amounts, so that the transmission time difference or the transmission phase difference of light in the two optical waveguide devices is correspondingly changed, the deformation degree of the two first vibrating films is detected, and the intensity of an acoustic signal is sensed.

2. The optical detection-based acoustic sensor of claim 1, wherein two of the first diaphragms have a pre-deformation amount of protruding bending toward each other.

3. The acoustic sensor based on optical detection according to claim 1, wherein the optical waveguide device is provided with a waveguide channel, the waveguide channel is spiral, and a light receiving end and a light emitting end are respectively provided on both ends of the waveguide channel outside the spiral.

4. An optical detection based acoustic sensor according to claim 3 wherein the waveguide channel is surrounded by a dielectric layer.

5. An optical detection based acoustic sensor according to claim 3 wherein the waveguide channel material comprises silicon.

6. The optical detection-based acoustic sensor of any of claims 1-5, wherein the first diaphragm is further provided with a stationary electrode.

7. The optical detection-based acoustic sensor of claim 6, wherein a vibrating electrode is further suspended above the fixed electrode.

8. The optical detection-based acoustic sensor of claim 7, wherein a plurality of acoustic holes for conducting acoustic waves are distributed on the fixed electrode and the vibrating electrode.

9. The optical detection-based acoustic sensor of claim 7, wherein a support layer is provided between the stationary electrode and the vibrating electrode, and a resonant cavity is formed therebetween.

10. The optical detection-based acoustic sensor of claim 7, 8 or 9, wherein the stationary electrode and the vibrating electrode are in a flat state.