Mems sound transducer having recesses and projections

Patent metadata

Field	Value
Publication number	US-2023421947-A1
Application number	US-202318466082-A
Country	US
Kind code	A1
Filing date	Sep 13, 2023
Priority date	Mar 16, 2021
Publication date	Dec 28, 2023
Grant date	—

Abstract

Embodiments of the present disclosure describe MEMS sound transducers for generating sound, having an actuator, wherein the actuator is separated from a surrounding structure by one or more gaps and is configured to execute a relative movement between the actuator and the surrounding structure. Additionally, the MEMS sound transducer has the surrounding structure, wherein the actuator and the surrounding structure has a plurality of recesses and projections which are separated by one or more gaps, wherein the plurality of projections belonging to the actuator are arranged to interdigitate into the plurality of recesses belonging to the surrounding structure, and/or the plurality of projections belonging to the surrounding structure to interdigitate into the plurality of recesses belonging to the actuator.

First claim

1 . A method for manufacturing an MEMS sound transducer for generating sound, comprising:
providing an actuator and a surrounding structure, wherein the actuator is separated from the surrounding structure by one or more gaps and is configured to execute a relative movement between the actuator and the surrounding structure, and wherein the actuator and the surrounding structure comprise a plurality of recesses and projections, wherein the plurality of projections belonging to the actuator are arranged to interdigitate into the plurality of recesses belonging to the surrounding structure, and/or the plurality of projections belonging to the surrounding structure to interdigitate into the plurality of recesses belonging to the actuator, forming the interdigitating elements such that the interdigitating elements are thus separated by the one or more gaps, and such that overlapping areas of the plurality of recesses and projections are configured such that the interdigitating elements comprise a frequency-depending attenuation function with a relative movement between the actuator and the surrounding structure to suppress harmonic distortions; and wherein the overlapping areas are directly opposite areas moving past each other by the relative movement.

2 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein an aspect ratio of height/width of the plurality of recesses and projections, the overlapping areas of actuator and surrounding structure which move past each other by the relative movement, and the distance of the overlapping areas of actuator and surrounding structure are configured to adjust a frequency-dependent attenuation to suppress harmonic distortions,
wherein the height is a height orthogonally to a surface of the actuator or the surrounding structure on which the projection is arranged, and wherein the width is a width in parallel to the surface of the actuator or the surrounding structure on which the projection is arranged.

3 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the surrounding structure is formed by a substrate.

4 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the plurality of recesses and projections are implemented as microstructures comprising an aspect ratio between height/width of more than 5, wherein the height is a height orthogonally to a surface of the actuator or the surrounding structure on which the projection is arranged; and
wherein the width is a width in parallel to the surface of the actuator or the surrounding structure on which the projection is arranged.

5 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the actuator comprises a piezoelectric or magnetic or electrostatic drive; and/or
wherein the actuator is formed by a bending transducer.

6 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the projections of the plurality of projections comprise a height of more than 50 μm, and wherein the height is a height orthogonally to a surface of the actuator or the surrounding structure on which the respective projection is arranged.

7 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the plurality of projections are implemented as columns and/or combs, and wherein the plurality of recesses are implemented as holes and/or slots.

8 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the plurality of recesses and projections are made of at least one of silicon, silicon compounds, metals or polymers.

9 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the MEMS sound transducer is configured to generate signals in a frequency range of at least 20 Hz and/or up to 20 kHz; and/or
wherein the MEMS sound transducer is an MEMS ultrasonic transducer, the MEMS ultrasonic transducer being configured to generate signals in a frequency range of at least 20 kHz and/or up to 100 MHz.

10 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the one or more gaps comprise a width of less than 20 μm, less than 10 μm or less than 5 μm, or, generally, comprise a width in a range between 0.1 and 20 μm.

11 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the actuator is implemented as a bending actuator, and wherein the bending actuator and the surrounding structure are laterally opposite each other in a plane; and
wherein the bending actuator is suspended relative to the surrounding structure at least on one side; and wherein the bending actuator is configured to execute, with an end of the bending actuator, the relative movement between the bending actuator and the surrounding structure at least partially perpendicularly to the plane; and wherein, at the moveable end of the bending actuator, a plurality of recesses and/or projections in the form of a first comb structure are implemented, in the common plane of the bending actuator and the surrounding structure; and wherein the surrounding structure comprises a plurality of recesses and/or projections in the form of a second comb structure on a side facing the movable end of the bending actuator, wherein the first and second comb structures are configured to interdigitate.

12 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the actuator is implemented as a lifting actuator, and wherein the lifting actuator and the surrounding structure are arranged in a plane; and
wherein the lifting actuator is configured to execute the relative movement between the lifting actuator and the surrounding structure perpendicularly to the plane; and wherein the lifting actuator comprises a plurality of recesses and/or projections in the form of a first comb structure along its periphery in the plane; and wherein the surrounding structure comprises a plurality of recesses and/or projections in the form of a second comb structure on a side facing the first comb structure; and wherein the first and the second comb structures are configured to interdigitate.

13 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the actuator is arranged in a first plane, and wherein the surrounding structure is arranged in a second plane, the first and second planes being parallel to each other; and
wherein the actuator is configured to execute the relative movement between the actuator and the surrounding structure perpendicularly to the first and second planes; and wherein the actuator comprises a plurality of projections in the form of columns and/or combs, wherein the columns and/or combs are arranged on a surface of the actuator facing the surrounding structure, perpendicularly to the parallel planes; and wherein the surrounding structure comprises a plurality of recesses in the form of holes and/or slots; and wherein the columns and/or combs of the actuator and the holes and/or slots of the surrounding structure are configured to interdigitate.

14 . The method for manufacturing an MEMS sound transducer in accordance with claim 1 , wherein the surrounding structure is arranged in a first plane, and wherein the actuator is arranged in a second plane, the first and second planes being parallel to each other; and
wherein the actuator is configured to execute the relative movement between the actuator and the surrounding structure perpendicularly to the first and second planes; and

Assignees

• Fraunhofer Ges Forschung

Inventors

• Stoppel Fabian
• Niekiel Malte Florian
• Wagner Bernhard
• Lofink Fabian

Classifications

• H04R1/22 Primary

  for obtaining desired frequency characteristic only  {(circuit for combining transducers having different responses H04R3/00; for hearing aids H04R25/407)} · CPC title

• H04R2201/003

  Mems transducers or their use · CPC title

• H04R17/00

  Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00}) · CPC title

• H04R19/02

  Loudspeakers (H04R19/01 takes precedence) · CPC title