# US 12,225,821 B1 · Method of making acoustic devices with edge corrugation

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- Number: US 12,225,821 B1
- Document ID: US12225821B1
- Status: Granted
- Kind: B1
- Application number: 17/647,213
- Filed: 2022-01-06
- Granted: 2025-02-11
- Earliest claimed: 2021-01-07
- Assignees: Skyworks Global Pte. Ltd.
- Applicants: Skyworks Global Pte. Ltd.
- Inventors: You Qian; Rakesh Kumar; Guofeng Chen; Myeong Gweon Gu; Myung Hyun Park; Jae Hyung Lee; Michael Jon Wurtz
- Web page: https://patentgrep.com/patent/US12225821B1

## CPC

- H04R 17/02: Microphones
- B81B 3/0021: {Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00)}
- B81C 1/00134: {comprising flexible or deformable structures (manufacture of MEMS devices for specific applications, see relevant places, e.g. gyroscopes G01C19/5719, pressure sensors G01L9/0042, accelerometers G01P15/0802, acoustic transducers or diaphragms therefor H04R31/00)}
- G10L 19/00: Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis (in musical instruments G10H)
- H04R 7/06: comprising a plurality of sections or layers
- H04R 17/10: Resonant transducers, i.e. adapted to produce maximum output at a predetermined frequency
- H04R 19/04: Microphones (H04R19/01 takes precedence)
- H04R 31/003: {for diaphragms or their outer suspension}
- H10N 30/01: Manufacture or treatment
- H10N 30/302: {Sensors}
- B81B 2201/0257: Microphones or microspeakers
- B81B 2203/0118: Cantilevers
- B81B 2203/019: characterized by their profile
- B81B 2203/04: Electrodes
- H04R 1/222: {for microphones (H04R1/24, H04R1/26 take precedence)}
- H04R 7/22: Clamping rim of diaphragm or cone against seating
- H04R 2201/003: Mems transducers or their use
- H04R 2207/021: Diaphragm extensions, not necessarily integrally formed, e.g. skirts, rims, flanges
- H04R 2410/03: Reduction of intrinsic noise in microphones
- H04R 2499/11: Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01)
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

A method of making an acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) includes forming or providing a mold having one or more grooves in a top surface of the mold that extend in a direction of the length of the mold to a distal end of the mold. The method also includes forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam, the distal portion of the beam having a corrugated section including one or more grooves that correspond to the grooves of the mold. The method also includes forming a gap in the structure to define two beams separated by the gap, and releasing the structure from the mold to form one or more cantilever beams that increases an acoustic resistance of the gap between sensors.

## Claims

### Claim 1

A method of making a piezoelectric sensor for a piezoelectric microelectromechanical systems microphone, comprising:
forming or providing a mold extending along a length and having one or more grooves in a top surface of the mold, the one or more grooves extending in a direction of the length of the mold to a distal end of the mold;
forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam with a proximal portion and a distal portion, the distal portion having a corrugated section including one or more grooves that correspond to the grooves of the mold;
forming a gap in the structure to define two beams with free ends separated by the gap; and
releasing the structure from the mold to form two cantilever beams having said free ends separated by the gap, the two cantilever beams configured to move independently of each other.

### Claim 2 (depends on 1)

The method of claim 1 further comprising forming or applying an electrode to the proximal portion of the structure.

### Claim 3 (depends on 1)

The method of claim 1 wherein the corrugated section has two grooves, the gap formed between the two grooves.

### Claim 4 (depends on 3)

The method of claim 3 wherein the two grooves extend parallel to each other in a second direction generally transverse to the first direction.

### Claim 5 (depends on 1)

The method of claim 1 wherein a thickness of the beam between a top surface and a bottom surface is greater in the corrugated section than in the proximal portion of the beam.

### Claim 6 (depends on 1)

The method of claim 1 wherein the one or more grooves defines a wall portion of the beam that extends perpendicular to the first direction.

### Claim 7 (depends on 6)

The method of claim 6 wherein the wall portion extends downward relative to a bottom side of the beam.

### Claim 8 (depends on 1)

The method of claim 1 further comprising forming or providing a stepped portion on the mold prior to forming the one or more grooves in the mold.

### Claim 9 (depends on 8)

The method of claim 8 wherein the one or more grooves defines a wall portion of the beam that extends perpendicular to the first direction, the wall portion extending upward relative to a top side of the beam and downward relative to a bottom side of the beam.

### Claim 10

A method of making an electronic device, comprising:
forming or providing a printed circuit board that includes a substrate layer;
forming or providing one or more piezoelectric microelectromechanical systems microphones via a process including (a) forming or providing a mold extending along a length and having one or more grooves in a top surface of the mold, the one or more grooves extending in a direction of the length of the mold to a distal end of the mold, (b) forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam with a proximal portion and a distal portion, the distal portion having a corrugated section including one or more grooves that correspond to the one or more grooves of the mold, (c) forming a gap in the structure to define two beams with free ends separated by the gap, (d) releasing the structure from the mold, and (d) leaving a part of the structure attached to a substrate in a cantilevered manner to form two cantilever beams having said free ends separated by the gap, the two cantilever beams configured to deflect independently of each other when subjected to sound pressure; and
mounting the one or more piezoelectric microelectromechanical systems microphones on the printed circuit board.

### Claim 11 (depends on 10)

The method of claim 10 further comprising forming or applying an electrode to the proximal portion of the structure.

### Claim 12 (depends on 10)

The method of claim 10 wherein the corrugated section has two grooves, the gap formed between the two grooves.

### Claim 13 (depends on 12)

The method of claim 12 wherein the two grooves extend parallel to each other in a second direction generally transverse to the first direction.

### Claim 14 (depends on 10)

The method of claim 10 wherein a thickness of the beam between a top surface and a bottom surface is greater in the corrugated section than in the proximal portion of the beam.

### Claim 15 (depends on 10)

The method of claim 10 wherein the one or more grooves defines a wall portion of the beam that extends perpendicular to the first direction.

### Claim 16 (depends on 15)

The method of claim 15 wherein the wall portion extends downward relative to a bottom side of the beam.

### Claim 17 (depends on 10)

The method of claim 10 further comprising forming or providing a stepped portion on the mold prior to forming the one or more grooves in the mold.

### Claim 18 (depends on 17)

The method of claim 17 wherein the one or more grooves defines a wall portion of the beam that extends perpendicular to the first direction, the wall portion extending upward relative to a top side of the beam and downward relative to a bottom side of the beam.