|Publication number||USRE42347 E1|
|Application number||US 11/903,207|
|Publication date||May 10, 2011|
|Filing date||Sep 20, 2007|
|Priority date||Oct 30, 1998|
|Also published as||US6088463, USRE42346|
|Publication number||11903207, 903207, US RE42347 E1, US RE42347E1, US-E1-RE42347, USRE42347 E1, USRE42347E1|
|Inventors||Pirmin Rombach, Matthias Müllenborn, Ole Hansen, Matthias Heschel, Siebe Bouwstra, Maja Amskov Gravad, Henrik Laurids Hvims|
|Original Assignee||Epcos Pte Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (27), Non-Patent Citations (16), Referenced by (9), Classifications (10), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,088,463. This application is a divisional of U.S. patent application Ser. No. 10/193,055, entitled “Solid State Silicon-Based Condenser Microphone,” which was filed on Jul. 11, 2002, which is a reissue U.S. Pat. No. 6,088,463, issued on Jul. 11, 2000, which is hereby incorporated by reference in its entirety.
This invention related to miniature condenser microphones, and in particular to solid state silicon-based condenser microphones incorporating an integrated electronic circuit for transducer signal conditioning. Such miniature microphones are suitable for use in miniature electroacoustic devices such as hearing instruments.
In the hearing instruments industry one of the primary goals is to make hearing instruments of small size while still maintaining good electroacoustic performance and operability giving good user friendliness and satisfaction. Technical performance data comprise such as sensitivity, stability, compactness, robustness and insensitivity to electromagnetic interference and to other external and environmental conditions. In the past, several attempts have been made to make microphones smaller while still maintaining good technical performance data.
EP 561 566 discloses a solid state condenser microphone having a transducer chip and, on the same chip, an electronic circuit and a cavity forming an opening or sound inlet for the transducer. The techniques and processes for manufacturing such electronic circuitry are quite different from the techniques and processes used in manufacturing the transducer elements. Consequently a chip having both an electronic circuit and an opening therein requires two (or possibly more) separate stages of production, usually at different facilities.
The invention provides a solid state silicon-based condenser microphone which is suitable for batch production. Several silicon chips are stacked, and the subsequent dicinig of the stacked chips or discs is easier than with the prior art.
The invention makes it possible to make a very well defined sound inlet, which can optionally be covered with a sealing film or a filter preventing dust, moisture and other impurities from contaminating or obstructing the interior and the sound inlet of the microphone. A sound inlet can theoretically be made as an opening in any of the chip surfaces including the fractures after dicing, but in practice the fractures are irregular surfaces and therefore less suitable for supporting a sealing film or a filter, since the irregular fractures could give rise to the sealing film or a filter becoming wrinkled and having leakages at its periphery where it is secured to the die surface. A microphone according to the invention has an opening forming a sound inlet in the practically perfectly flat and polished faces of the wafer on which several individual microphones are arranged.
An integrated electronic circuit chip can be arranged on the same plane surface, which is perfectly suited for flip-chip mounting the electronic circuit chip.
An intermediate chip is arranged between the electronic circuit chip and the transducer chip. The intermediate chip has another opening with feedthrough electrical connections on a surface of the opening. The feedthrough connections establish electrical connections between the transducer element on the transducer chip and the electronic circuit chip. This gives a high degree of freedom in designing both the transducer chip and the electronic circuit chip and in particular their electrical terminations.
External electrical connections can be established economically and reliably, and thermal stresses can be avoided with the small size solid state silicon-based condenser microphone of the invention.
The invention uses a separate integrated electronic circuit chip, preferably a CMOS ASIC (Application Specific Integrated Circuit) which can be designed and manufactured separately and independent of the design and manufacture of the transducer portion of the microphone. This is advantageous since the techniques and processes for manufacturing integrated electronic circuit chips are different from those used in manufacturing transducer elements, and each production stage can thus be optimized individually and independent of each other.
In the following the invention will be explained with reference to the drawings, in which:
In the figures, for illustrative purposes, dimensions such as material thickness and mutual distances and possibly other proportions are not necessarily drawn to the same scale.
The illustrated microphone has the following structure. A silicon transducer chip 1 with a central opening etched therein carries a diaphragm 12 and a backplate 13 covering the central opening in the transducer chip. In this context the term “backplate” means a structural element which is relatively rigid as compared to the associated diaphragm, which in turn is relatively moveable. The backplate can be placed on either side of the diaphragm. The transducer chip with the diaphragm 12 and a backplate 13 are preferably manufactured as described in The copending Danish patent application PA 199800671. The transducer chip 1 and a backchamber-chip 17 having a cavity etched therein, and together the transducer chip 1 and the backchamber-chip 17 form a closed backchamber 11 with the diaphragm 12 forming one wall of the backchamber 11. The diaphragm 12 and the backplate 13 are both electrically conductive or semi-conductive and are arranged parallel and in close proximity to each other and with a well defined air gap in between, so that they form an electrical capacitor.
The backplate 13 has a plurality of perforations 19 making it acoustically transparent, and the diaphragm has a tiny vent hole 15 for equalising the static pressure on both sides of the diaphragm.
An electronic circuit chip 3 having an integrated circuit on a surface thereof is flip chip mounted with its circuit facing the transducer chip 1 and with an intermediate chip 2 between the transducer chip 1 and the electronic circuit chip 3. The intermediate chip 2 has a cavity 10 and a first through going opening 4 and a second through going opening 18 both communicating with the cavity 10. The intermediate chip 2 is secured to the transducer chip 1 by means of an electrically conductive solder ring 9 or by other means.
The electronic circuit chip 3 is secured to the intermediate chip 2 by means of an underfill material 6.
The diaphragm 12 and the backplate 13 are electrically connected Lo respective ones of solder bumps 8, which connect the diaphragm 12 and the backplate 13 to electrical feedthrough conductors 14 on the surface of the cavity 10 and the opening 18 and further to the upper surface of the intermediate chip 2 where connections to the electronic circuit chip 3 are established via a conventional flip-chip interconnect method e.g. gold studs 7 with conductive adhesive. This is most clearly seen in
The opening 4 is covered with a filter 5 or a flexible sheet or diaphragm of acoustically transparent material. The whole structure is encapsulated in a polymer encapsulation 16 leaving the filter 5 free.
The function of the above described structure is as follows. The opening 4 functions as a sound inlet, and ambient sound pressure enters through the filter 5 covering the opening 4 to the cavity 10 functioning as a front chamber for the microphone. Through the perforations 19 in the backplate 13 the sound pressure reaches the diaphragm 12. The cavity 11 functions as a backchamber for the microphone. The diaphragm 12 is movable relative to the backplate 13 in response to incident sound. When the diaphragm is moved in response to the incident sound, the electrical capacity of the electrical capacitor formed by the diaphragm 12 and the backplate 13 will vary in response to the incident sound. The circuit on the integrated circuit chip 3 is electrically connected to the diaphragm 12 And the backplate 13 via the electrical feedthrough conductors 14, and the circuit is designed to detect variations in the electrical capacity of the capacitor formed by the diaphragm 12 and the backplate 13. The circuit has electrical connections for electrically connecting it to a power supply and other electronic circuitry in eg a hearing instrument.
In the illustrated embodiment the transducer element on the transducer chip is a condenser microphone with a diaphragm and a single backplate. In an alternative embodiment the transducer element has its diaphragm arranged between two backplates. Such a microphone can give balanced output signal which is less sensitive to electrical interference.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4922471||Mar 6, 1989||May 1, 1990||Sennheiser Electronic Kg||Capacitive sound transducer|
|US5146435||Dec 4, 1989||Sep 8, 1992||The Charles Stark Draper Laboratory, Inc.||Acoustic transducer|
|US5255246||Sep 17, 1992||Oct 19, 1993||Siemens Nederland N.V.||Electroacoustic transducer of the electret type|
|US5303210||Oct 29, 1992||Apr 12, 1994||The Charles Stark Draper Laboratory, Inc.||Integrated resonant cavity acoustic transducer|
|US5452268||Aug 12, 1994||Sep 19, 1995||The Charles Stark Draper Laboratory, Inc.||Acoustic transducer with improved low frequency response|
|US5490220||May 5, 1994||Feb 6, 1996||Knowles Electronics, Inc.||Solid state condenser and microphone devices|
|US5531787||Jan 25, 1993||Jul 2, 1996||Lesinski; S. George||Implantable auditory system with micromachined microsensor and microactuator|
|US5573679||Jun 19, 1995||Nov 12, 1996||Alberta Microelectronic Centre||Fabrication of a surface micromachined capacitive microphone using a dry-etch process|
|US5658710||Feb 24, 1995||Aug 19, 1997||Adagio Associates, Inc.||Method of making superhard mechanical microstructures|
|US5659195||Jun 8, 1995||Aug 19, 1997||The Regents Of The University Of California||CMOS integrated microsensor with a precision measurement circuit|
|US5677965||Sep 20, 1994||Oct 14, 1997||Csem Centre Suisse D'electronique Et De Microtechnique||Integrated capacitive transducer|
|US5717631||Jul 25, 1995||Feb 10, 1998||Carnegie Mellon University||Microelectromechanical structure and process of making same|
|US5740258||Jun 5, 1995||Apr 14, 1998||Mcnc||Active noise supressors and methods for use in the ear canal|
|US5870482||Feb 25, 1997||Feb 9, 1999||Knowles Electronics, Inc.||Miniature silicon condenser microphone|
|US5970315||Oct 3, 1997||Oct 19, 1999||Carnegie Mellon University||Microelectromechanical structure and process of making same|
|US6178249||Jun 17, 1999||Jan 23, 2001||Nokia Mobile Phones Limited||Attachment of a micromechanical microphone|
|US6806593||May 15, 2001||Oct 19, 2004||California Institute Of Technology||Thin film electret microphone|
|DE3325961A1||Jul 19, 1983||Jan 31, 1985||Dietmar Hohm||Silicon-based capacitive transducers incorporating silicon dioxide electret|
|EP0490486A2||Nov 11, 1991||Jun 17, 1992||Wisconsin Alumni Research Foundation||Micromachined differential pressure transducers and method of producing the same|
|EP0561566A2||Mar 11, 1993||Sep 22, 1993||Knowles Electronics, Inc.||Solid state condenser and microphone|
|EP0783108A1||Dec 18, 1996||Jul 9, 1997||Siemens Aktiengesellschaft||Micromechanical element with planarized cover over a cavity and method of fabrication|
|JPH0937382A||Title not available|
|WO1993019343A1||Mar 15, 1993||Sep 30, 1993||Lynxvale Limited||Micromechanical sensor|
|WO1994025863A2||May 5, 1994||Nov 10, 1994||Siemens Aktiengesellschaft||Process for depositing a large-surface layer through a mask and optional closure of said mask|
|WO1994030030A1||May 24, 1994||Dec 22, 1994||The Regents Of The University Of California||Microfabricated acoustic source and receiver|
|WO1995034917A1||May 3, 1995||Dec 21, 1995||The Regents Of The University Of California||Cantilever pressure transducer|
|WO1997001258A1||Jun 21, 1996||Jan 9, 1997||Microtronic A/S||Micromechanical microphone|
|1||Bay, Jesper, et al., "Design Of A Silicon Microphone With Differential Read-Out Of A Sealed Double Parallel-Plate Capacitor," Sensors and Actuators A, vol. 53, pp. 232-236 (1996).|
|2||Bouwstra, Siebe, et al., "Silicon Microphones-A Danish Perspective," J. Micromech. Microeng., vol. 8, pp. 64-68 (1998).|
|3||Bouwstra, Siebe, et al., "Silicon Microphones—A Danish Perspective," J. Micromech. Microeng., vol. 8, pp. 64-68 (1998).|
|4||Chowdhury, Sazzadur, et al., "MEMS Acousto-Magnetic Components for Use In A Hearing Instrument," Presentation at SPIE's Symposium on Design, Test, Integration, and Packaging of MEMS/MOEMS, 14 pages (May 9-11, 2000).|
|5||Dehé, A., et al., "Silicon Micromachined Microphone Chip At Siemens," 4 pages (no date).|
|6||Emkay Innovative Products, "Surface Mount Microphones: A New Options for OEMs," EPN, 2 pages (Jun. 11, 2002).|
|7||Emkay Innovative Products, Brochure for "SiSonic(TM) Silicon Microphone," 2 pages (no date).|
|8||Emkay Innovative Products, Brochure for "SiSonic™ Silicon Microphone," 2 pages (no date).|
|9||Emkay Innovative Products, Press Release for "Advancement In Silicon Technology Leads To Partnership With Institute Of Microelectronics-Singapore," 2 pages (Jan. 9, 1998).|
|10||Emkay Innovative Products, Press Release for "Advancement In Silicon Technology Leads To Partnership With Institute Of Microelectronics—Singapore," 2 pages (Jan. 9, 1998).|
|11||Hsu, P.-C, et al., "A High Sensitivity Polysilicon Diaphragm Condenser Microphone," Presentation at MEMS Conference, 6 pages (Jan. 25-29, 1998).|
|12||Müllenborn, Matthias, "Microsystems For Hearing Instruments," Micro Structure Bulletin, No. 3, 1 page (Aug. 1998).|
|13||Ouellette, Jennifer, "The Incredible Shrinking Microphone," The Industrial Physicist, 3 pages (Aug. 1999).|
|14||Scheeper, P. R., et al., "Fabrication Of Silicon Condenser Microphones Using Single Wafer Technology," Journal Of Microelectromechanical Systems, vol. 1, No. 3, pp. 147-154 (Sep. 1992).|
|15||SonionMEMS, Brochure for Silicon Microphone, 4 pages (no date).|
|16||van der Donk, A.G.H., et al., "Preliminary Results Of A Silicon Condenser Microphone With Internal Feedback," IEEE, pp. 262-265 (1991).|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US8542850||Sep 2, 2008||Sep 24, 2013||Epcos Pte Ltd||Miniature microphone assembly with hydrophobic surface coating|
|US8674498||Dec 4, 2008||Mar 18, 2014||Epcos Ag||MEMS package and method for the production thereof|
|US8761418 *||Oct 12, 2012||Jun 24, 2014||Robert Bosch Gmbh||Microelectromechanical loudspeaker array with predetermined period of time of diaphragm relaxation|
|US9056760||Jan 24, 2011||Jun 16, 2015||Epcos Ag||Miniaturized electrical component comprising an MEMS and an ASIC and production method|
|US20090067659 *||Sep 2, 2008||Mar 12, 2009||Christian Wang||Miniature microphone assembly with hydrophobic surface coating|
|US20110006381 *||Dec 4, 2008||Jan 13, 2011||Epcos Ag||Mems package and method for the production thereof|
|US20110180924 *||Feb 18, 2010||Jul 28, 2011||Lingsen Precision Industries, Ltd.||Mems module package|
|US20130094679 *||Oct 12, 2012||Apr 18, 2013||Robert Bosch Gmbh||Microelectromechanical loudspeaker array, and method for operating a microelectromechanical loudspeaker array|
|US20160050499 *||Oct 23, 2015||Feb 18, 2016||Invensense, Inc.||Noise mitigating microphone system|
|U.S. Classification||381/174, 381/191, 367/181, 381/175, 367/174|
|International Classification||H04R25/00, H04R19/00|
|Cooperative Classification||H04R19/04, H04R19/005|
|Feb 13, 2008||AS||Assignment|
Owner name: SONION ROSKILDE A/S, DENMARK
Free format text: CHANGE OF NAME;ASSIGNOR:MICROTRONIC A/S;REEL/FRAME:020505/0808
Effective date: 20060328
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ROSKILDE, SONION;REEL/FRAME:020562/0623
Effective date: 20070531
Owner name: MICROTRONIC A/S, DENMARK
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ROMBACH, PIRMIN;MULLENBOM, MATTHIAS;HANSEN, OLE;AND OTHERS;SIGNING DATES FROM 19981221 TO 19990107;REEL/FRAME:020564/0413
|Jan 11, 2012||FPAY||Fee payment|
Year of fee payment: 12
|Jun 29, 2013||AS||Assignment|
Owner name: EPCOS PTE LTD, SINGAPORE
Free format text: ASSET TRANSFER AGREEMENT;ASSIGNOR:PULSE MEMS APS;REEL/FRAME:030743/0262
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|Jan 31, 2017||AS||Assignment|
Owner name: TDK CORPORATION, JAPAN
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