U.S. patent number RE42,347 [Application Number 11/903,207] was granted by the patent office on 2011-05-10 for solid state silicon-based condenser microphone.
This patent grant is currently assigned to Epcos PTE Ltd.. Invention is credited to Siebe Bouwstra, Jorgen B. Elmer, legal representative, Maja Amskov Gravad, Ole Hansen, Matthias Heschel, Henrik Laurids Hvims, Matthias Mullenborn, Pirmin Rombach.
United States Patent |
RE42,347 |
Rombach , et al. |
May 10, 2011 |
Solid state silicon-based condenser microphone
Abstract
A solid state silicon-based condenser microphone comprising a
silicon transducer chip (1). The transducer chip includes a
backplate (13) and a diaphragm (12) arranged substantially parallel
to each other with a small air gap in between, thereby forming an
electrical capacitor. The diaphragm (12) is movable relative to the
backplate (13) in response to incident sound. An integrated
electronic circuit chip (3) or ASIC is electrically coupled to the
transducer chip (1). An intermediate layer (2) fixes the transducer
chip (1) to the integrated electronic circuit chip (3) with the
transducer chip (1) on a first side of the intermediate layer (2)
and the integrated electronic circuit chip (3) on a second side of
the intermediate layer (2) opposite the first side. The
intermediate layer (2) has a sound inlet (4) on the same side as
the ASIC giving access of sound to the diaphragm.
Inventors: |
Rombach; Pirmin (Kongens
Lyngby, DK), Mullenborn; Matthias (Lyngby,
DK), Hansen; Ole (Horsholm, DK), Heschel;
Matthias (Rodovre, DK), Bouwstra; Siebe
(Amsterdam, NL), Gravad; Maja Amskov (Tune,
DK), Hvims; Henrik Laurids (Horsholm, DK),
Elmer, legal representative; Jorgen B. (Horsholm,
DE) |
Assignee: |
Epcos PTE Ltd. (Singapore,
SG)
|
Family
ID: |
22669506 |
Appl.
No.: |
11/903,207 |
Filed: |
September 20, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
10193055 |
Jul 11, 2002 |
|
|
|
Reissue of: |
09182668 |
Oct 30, 1998 |
6088463 |
Jul 11, 2000 |
|
|
Current U.S.
Class: |
381/174; 367/181;
367/174; 381/191; 381/175 |
Current CPC
Class: |
H04R
19/005 (20130101); H04R 19/04 (20130101) |
Current International
Class: |
H04R
25/00 (20060101) |
Field of
Search: |
;381/369,173-176,191
;367/181,172-174 ;29/603.18 ;361/283.3-4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
33 25 961 |
|
Jan 1985 |
|
DE |
|
3325961 |
|
Jan 1985 |
|
DE |
|
0 490 486 |
|
Jun 1992 |
|
EP |
|
0 490 486 |
|
Jun 1992 |
|
EP |
|
0 561 566 |
|
Sep 1993 |
|
EP |
|
0 561 566 |
|
Sep 1993 |
|
EP |
|
0 783 108 |
|
Jul 1997 |
|
EP |
|
0 783 108 |
|
Jul 1997 |
|
EP |
|
09037382 |
|
Feb 1997 |
|
JP |
|
WO 93/19343 |
|
Sep 1993 |
|
WO |
|
94/25863 |
|
Nov 1994 |
|
WO |
|
WO 94/25863 |
|
Nov 1994 |
|
WO |
|
WO 94/30030 |
|
Dec 1994 |
|
WO |
|
95/34917 |
|
Dec 1995 |
|
WO |
|
WO 95/34917 |
|
Dec 1995 |
|
WO |
|
97/-01258 |
|
Jan 1997 |
|
WO |
|
WO 97/01258 |
|
Jan 1997 |
|
WO |
|
Other References
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). cited by
other .
Bouwstra, Siebe, et al., "Silicon Microphones--A Danish
Perspective," J. Micromech. Microeng., vol. 8, pp. 64-68 (1998).
cited by other .
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). cited by other .
Dehe, A., et al., "Silicon Micromachined Microphone Chip At
Siemens," 4 pages (no date). cited by other .
van der Donk, A.G.H., et al., "Preliminary Results Of A Silicon
Condenser Microphone With Internal Feedback," IEEE, pp. 262-265
(1991). cited by other .
Emkay Innovative Products, Brochure for "SiSonic.TM. Silicon
Microphone," 2 pages (no date). cited by other .
Emkay Innovative Products, "Surface Mount Microphones: A New
Options for OEMs," EPN, 2 pages (Jun. 11, 2002). cited by other
.
Emkay Innovative Products, Press Release for "Advancement In
Silicon Technology Leads To Partnership With Institute Of
Microelectronics--Singapore," 2 pages (Jan. 9, 1998). cited by
other .
Hsu, P.-C, et al., "A High Sensitivity Polysilicon Diaphragm
Condenser Microphone," Presentation at MEMS Conference, 6 pages
(Jan. 25-29, 1998). cited by other .
Mullenborn, Matthias, "Microsystems For Hearing Instruments," Micro
Structure Bulletin, No. 3, 1 page (Aug. 1998). cited by other .
Ouellette, Jennifer, "The Incredible Shrinking Microphone," The
Industrial Physicist, 3 pages (Aug. 1999). cited by other .
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). cited by other .
SonionMEMS, Brochure for Silicon Microphone, 4 pages (no date).
cited by other.
|
Primary Examiner: Ni; Suhan
Attorney, Agent or Firm: Nixon Peabody LLP
Parent Case Text
.Iadd.RELATED APPLICATIONS .Iaddend.
.Iadd.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. .Iaddend.
Claims
What is claimed is:
.[.1. A solid state silicon-based condenser microphone comprising a
silicon transducer chip (1) including a backplate (13) and a
diaphragm (12) arranged substantially parallel to each other,
thereby forming an electrical capacitor, the diaphragm (12) being
movable relative to the backplate (13) in response to incident
sound, an integrated electronic circuit chip (3) electrically
coupled to the transducer chip (1), an intermediate layer (2)
fixing the transducer chip (1) to the integrated electronic circuit
chip (3) in a spaced relationship, with the transducer chip (1) on
a first side of the intermediate layer (2) and the integrated
electronic circuit chip (3) on a second side of the intermediate
layer (2) opposite the first side, the intermediate layer (2)
having a first through going opening (4, 10) between its first side
and its second side giving access of sound to the diaphragm..].
.[.2. A condenser microphone according to claim 1 wherein the
intermediate layer (2) on a surface thereof has electrical
conductors (14) electrically connecting the transducer chip (1) to
the integrated circuit chip (3)..].
.[.3. A condenser microphone according to claim 2 wherein the
intermediate layer (2) has a second through going opening (18) with
a surface on which the electrical conductors (14) electrically
connecting the transducer chip (1) to the integrated circuit chip
(3) are situated..].
.[.4. A condenser microphone according to claim 1 wherein the
opening (4) in the intermediate layer is covered with a film (5)
sealing the opening (4) on the second side of the intermediate
layer (2)..].
.[.5. A condenser microphone according to claim 1 wherein a cavity
(11) is provided in the transducer chip (1) on a side of the
diaphragm (12) opposite the intermediate layer (2)..].
.[.6. A condenser microphone according to claim 5 wherein the
cavity (11) is a closed cavity..].
.[.7. A condenser microphone according to claim 2 wherein the
integrated electronic circuit chip (3) has a surface including
electronic circuits with said surface facing the intermediate layer
(2)..].
.[.8. A condenser microphone according to claim 1 wherein the
intermediate layer (2) is a silicon-based chip..].
.Iadd.9. A silicon-based electroacoustic transducer, comprising: a
silicon-based transducer chip for transducing between acoustic
signals and electrical signals, wherein said silicon-based
transducer chip includes a backplate and a diaphragm; a
silicon-based integrated electronic circuit chip; and an
intermediate element secured to said silicon-based transducer chip
and to said integrated electronic circuit chip, said intermediate
element including an electrical conductor electrically coupling
said integrated electronic circuit chip and said transducer chip,
said electrical signals being transmitted along said electrical
conductor. .Iaddend.
.Iadd.10. The silicon-based electroacoustic transducer of claim 9,
wherein said silicon-based integrated electronic circuit chip is an
ASIC chip. .Iaddend.
.Iadd.11. The silicon-based electroacoustic transducer of claim 9,
wherein said silicon-based integrated electronic circuit chip is
flip-chip mounted to said intermediate element. .Iaddend.
.Iadd.12. The silicon-based electroacoustic transducer of claim 9,
wherein said intermediate element includes a feed-through, said
feed-through including a feed-through conductor leading to said
silicon-based integrated electronic circuit chip. .Iaddend.
.Iadd.13. The transducer of claim 9, wherein the intermediate
element has a first surface and a second surface opposing said
first surface, said silicon-based transducer being mounted to said
first surface, said intermediate element further including an
acoustic port on said second surface leading to an acoustic passage
extending to said first surface of said intermediate element, said
acoustic passage for transmitting said acoustic signals to said
transducer chip mounted on said first surface of said intermediate
element; and a filter adjacent to said acoustic port for preventing
contamination of said acoustic passage. .Iaddend.
.Iadd.14. The transducer of claim 9, wherein the integrated
electronic circuit chip has an integrated circuit on a surface
thereof. .Iaddend.
Description
FIELD OF THE INVENTION
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.
BACKGROUND OF THE INVENTION
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.
SUMMARY OF THE INVENTION
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.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following the invention will be explained with reference to
the drawings, in which:
FIG. 1 is a cross section of a microphone according to the
invention, and
FIG. 2 is an enlarged view of a portion of the microphone in FIG.
1.
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.
DETAILED DESCRIPTION OF THE INVENTION
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 FIG. 2.
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.
* * * * *