MEMS devices and processes

• US 11,197,103 B2
• Filed: 04/17/2018
• Issued: 12/07/2021
• Est. Priority Date: 04/28/2017
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Piechocinski, Marek Sebastian
• Primary Examiner(s): Ensey, Brian
• Application Number:
  US16/606,932
• Publication Number:
  US 20200137501A1
• Time in Patent Office: 1,330 Days
• CPC Class Codes: B01D 2279/45 for electronic devices, e.g. computers, hard-discs, mobile phones
• CPC Class Codes: B01D 46/10 Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81B 7/0064 for protecting against electromagnetic or electrostatic interferences
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 2201/0105 Sacrificial layer
• CPC Class Codes: B81C 2201/0132 Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling
• CPC Class Codes: H04R 1/086 Protective screens, e.g. all weather or wind screens
• CPC Class Codes: H04R 19/005 using semiconductor materials
• 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 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

Abstract

MEMS devices comprise a filter configured and arranged to inhibit the entry of particles into at least a region of the interior of the substrate cavity from a region underlying the substrate.

Claims

1. A MEMS transducer comprising:

a substrate having a cavity which extends through the substrate;

a membrane which overlies the cavity;

a backplate; and

a filter configured and arranged to inhibit the entry of particles into at least a region of the interior of the substrate cavity from a region underlying the substrate;

wherein the filter is formed from the material that forms one or more of a dielectric layer and an oxidation layer of the MEMS transducer.

4. The MEMS transducer as claimed in claim 1, wherein the filter comprises a barrier for substantially inhibiting the flow of particles through the filter to a region upstream of the filter.

5. The MEMS transducer as claimed in claim 1, wherein the filter comprises a plurality of holes which extend through the filter, the plurality of holes being configured to substantially allow the transmission of acoustic sound waves through the filter.

6. The MEMS transducer as claimed in claim 1, wherein the filter comprises at least one surface which is hydrophobic.

7. The MEMS transducer as claimed in claim 6 wherein the underside of the filter is provided with a hydrophobic coating.

8. The MEMS transducer as claimed in claim 1, wherein the filter is provided at, or near, the bottom of the substrate.

9. The MEMS transducer as claimed in claim 1, wherein said filter is formed from the material that forms a conductive layer of the MEMS transducer.

10. The MEMS transducer as claimed in claim 1, wherein said filter is formed from silicon nitride.

11. The MEMS transducer as claimed in claim 1, wherein the filter is recessed or embedded within the substrate cavity.

12. The MEMS transducer as claimed in claim 1, wherein the filter is provided by a layer formed during the fabrication of the MEMS transducer.

13. The MEMS transducer as claimed in claim 1, wherein the membrane layer is supported relative to the substrate of the transducer so as to define a flexible membrane of the transducer.

14. The MEMS transducer as claimed in claim 1, comprising a back-plate structure wherein the membrane is supported with respect to said back-plate structure.

15. The MEMS transducer as claimed in claim 14 wherein said back-plate structure comprises a plurality of holes through the back-plate structure.

16. The MEMS transducer as claimed in claim 1, wherein said transducer comprises a capacitive sensor.

17. The MEMS transducer as claimed in claim 1, wherein said transducer comprises a microphone.

18. The MEMS transducer as claimed in claim 16 further comprising readout circuitry.

19. An electronic device comprising a MEMS transducer as claimed in claim 1, wherein said device is at least one of:

a portable device;

a battery powered device;

an audio device;

a computing device;

a communications device;

a personal media player;

a mobile telephone;

a games device; and

a voice controlled device.

2. A MEMS transducer comprising:

a substrate having a cavity which extends through the substrate from a first opening in a first side of the substrate to a second opening in a second side of the substrate;

a backplate;

a membrane which is supported relative to the second side of substrate and overlies the cavity;

an integrated filter provided within the substrate cavity or at/across the first opening of the substrate cavity;

wherein the integrated filter is formed from the material that forms one or more of a dielectric layer and an oxidation layer of the MEMS transducer.

3. A MEMS transducer comprising a backplate and a flexible membrane supported relative to a substrate cavity, the transducer having an integrated filter for providing environmental protection to at least a region of the substrate cavity;

wherein the integrated filter is formed from the material that forms one or more of a dielectric layer and an oxidation layer of the MEMS transducer.

20. A MEMS transducer comprising:

a substrate having a cavity which extends through the substrate;

a membrane which overlies the cavity;

a backplate; and

an integrated filter configured and arranged to inhibit the entry of particles into at least a region of the interior of the substrate cavity from a region underlying the substrate;

wherein the integrated filter is formed from the material that forms one or more of a dielectric layer and an oxidation layer of the MEMS transducer.

21. A MEMS transducer comprising:

a substrate having a cavity which extends through the substrate;

a membrane which overlies the cavity;

a structural layer comprising a plurality of acoustic holes arranged to allow free movement of air through the structural layer; and

an integrated filter configured and arranged to inhibit the entry of particles into at least a region of the interior of the substrate cavity from a region underlying the substrate;

wherein the membrane is arranged between the structural layer and the integrated filter; and

wherein the integrated filter is formed from the material that forms one or more of a dielectric layer and an oxidation layer of the MEMS transducer.