JP4459498B2 - Silicon-based sensor system - Google Patents

Abstract

The present invention relates to solid state silicon-based condenser microphone systems suitable for batch production. The combination of the different elements forming the microphone system is more flexible compared to any other system disclosed in the prior art. Electrical connections between the different elements of the microphone system are established economically and reliably via a silicon carrier using flip-chip technology. The invention uses an integrated electronic circuit chip, preferably an application specific integrated circuit (ASIC) which may be designed and manufactured separately and independent of the design and manufacture of the transducer element of the microphone. The complete sensor system can be electrically connected to an external substrate by surface mount technology with the contacts facing one side of the system that is not in conflict with the above-mentioned interface to the environment. This allows the user to apply simple and efficient surface mount techniques for the assembly of the overall system.

Description

[0001]
(Technical field of the invention)
The present invention relates to a sensor system including a carrier member, a conversion member, and an electronic device. The invention particularly relates to a condenser microphone system assembled using flip-chip technology. The invention further relates to a condenser microphone system adapted to be surface mounted, for example on a printed circuit board (PCB).
[0002]
(Background of the Invention)
In the hearing instrument and mobile communication systems industry, one of the main objectives is to create small sized components while maintaining good electroacoustic performance and providing good user friendliness and satisfaction. Technical performance data includes sensitivity, noise, stability, compactness, robustness, electromagnetic interference (EMI) and other insensitivity to external environmental conditions. In the past, several attempts have been made to maintain or improve technical performance data while making the microphone system smaller.
[0003]
Another problem in these component industries concerns ease of integration into the overall system.
[0004]
European patent EP561615 discloses a solid state condenser microphone having a field effect transistor (FET) circuit and a cavity or sound inlet on the same chip. The techniques and processes for manufacturing FET circuits are quite different from the techniques and processes used to manufacture transducer elements. Thus, the transducer element and FET system disclosed in EP561615 require two (or more) separate manufacturing steps, which makes manufacturing more complex and more expensive.
[0005]
Hybrid microelectromechanical systems (MEMS) have developed significantly in recent years. This must be done primarily with the development of appropriate technology to manufacture such systems. One advantage of such a hybrid system relates to the size with which it is possible to produce related complex systems including mechanical electronic converters and specially designed electronic devices.
[0006]
US Pat. No. 5,889,872 discloses a hybrid system consisting of a silicon microphone and an integrated circuit chip mounted thereon using wire bonding for electrical connection. This solution has the disadvantage of requiring protection and space for the bonding wires.
[0007]
US Pat. No. 5,856,914 discloses a micromechanical device such as a condenser microphone that is flip-chip mounted. Part of the carrier on which this microdevice is mounted forms part of the final system. The disadvantage of this system is the fact that micromechanical devices are not tested before being mounted on a carrier. Another drawback of this system is related to the material selected. The micromechanical device is made of Si, while the carrier is made of PCB or ceramic material. Differences in the coefficient of thermal expansion complicate the integration of such different materials.
[0008]
Danish journal Elektronik og Data, Volume 3, pages 4-8, 1998, “Fast Silicon-Based Microminiature Microphone” article shows how a silicon-based microphone system can be designed and manufactured Is disclosed. This article discloses a three-layer microphone system. Here, the transducer element is flip-chip mounted on an intermediate layer that connects the transducer element to an electronic device such as an application specific integrated circuit (ASIC). The transducer element consists of a movable diaphragm and a substantially rigid back plate. On the opposite side of the transducer element is mounted a silicon-based structure that forms the back chamber. It is worthless that wire bonding or direct soldering is required to connect the microphone system to the electrical periphery.
[0009]
It is an object of the present invention to provide a sensor system in which the different elements forming the sensor system are flip-chip mounted using standard batch-oriented technology.
[0010]
Another object of the present invention is to provide a fully functional and encapsulated sensor system which can operate independently of the final position on the PCB, for example.
[0011]
Yet another object of the present invention is to provide a fully functional and coated sensor system that can be tested prior to final implementation.
[0012]
Still another object of the present invention is to provide a sensor system that is suitable for mounting on, for example, a PCB using flip chip or surface mount technology and can avoid wire bonding and complex single chip handling. is there.
[0013]
Yet another object of the present invention is to provide a sensor system that can reduce the distance between the transducer element and the electronic circuit to reduce parasitics and space consumption.
[0014]
(Summary of Invention)
In the first aspect, the aforementioned purpose is
A carrier member having a first surface for holding first and second groups of contact elements;
An active member, the active element being electrically connected to the at least one contact element, wherein the at least one contact element is first to obtain an electrical contact between the active member and the carrier member. A transducer element coinciding with one of the contact elements of the group carrier member;
Consisting of an integrated circuit having at least one contact element, said at least one contact element coinciding with one of the contact elements of the second group of carrier members to obtain electrical contact between the integrated circuit and the carrier member Consisting of electronic devices
In order to obtain an electrical station contact between the active member of the transducer element and the integrated circuit of the electronic device, at least one contact element of the first group is electrically connected to the at least one contact element of the second group. This is accomplished by providing a connected sensor system.
[0015]
The transducer element can in principle be any type of transducer, such as a pressure transducer, an accelerometer, a thermometer.
[0016]
In order for the sensor system to communicate with the surroundings, the carrier member may further have a second surface holding a plurality of contact surface elements. At least one contact element of the first and second groups is electrically connected to one of the contact elements held by the second surface. The first surface and the second surface may be substantially parallel and opposed to each other.
[0017]
The carrier member and transducer element may be based on a semiconductor material such as Si. In order to relieve thermal stress, the carrier member, the transducer element and the electronic device may be based on the same semiconductor material. The material may be Si.
[0018]
Back chamber in order to apply the microphone - in order to form, with the carrier member further consistent with the active member of the transducer element (the align) recess (indentation). Also, for application to a microphone, the active member of the transducer element may comprise a capacitor formed by combining a flexible diaphragm and a substantially rigid back plate. In addition, the transducer element has a cavity or a sound inlet. The bottom of the cavity may be defined and formed by the active member of the transducer element. A flexible diaphragm and a substantially rigid backplate are electrically connected to the first and second contact elements of the transducer element, respectively, for transferring the signal received by the transducer element to the carrier member. Also good.
[0019]
The integrated circuit may be adapted for signal processing. This integrated circuit may be an ASIC.
[0020]
In order to obtain directional sensitivity, the sensor may further have an opening or sound inlet between the second surface of the carrier member and the recess.
[0021]
In order to protect the transducer element from eg particles and moisture, the outer surface of the sensor is at least partly protected by a lid. The lid of the transducer element and the active member may each define the upper and lower boundaries of the cavity. Furthermore, at least one outer surface of the sensor system may carry a conductive layer. The conductive layer may consist of a metal layer or a conductive polymer layer.
[0022]
The contact element may be made of a solder material such as Sn, SnAg, SnAu or SnPb. Furthermore, the sensor system may have sealing means for hermetically sealing the transducer element.
[0023]
In the second aspect, the present invention provides:
A carrier member having a first surface for holding first, second and third groups of contact elements;
An active member, the active member being electrically connected to at least one contact element, wherein the at least one contact element is a first group of carrier members to obtain electrical contact between the active member and the carrier member A first transducer element coinciding with one of the contact elements of
An active member, the active element being electrically connected to the at least one contact element, wherein the at least one contact element is a second group of carrier members to obtain electrical contact between the active member and the carrier member A second transducer element coinciding with one of the contact elements of
Consisting of an integrated circuit having at least one contact element, said at least one contact element coinciding with one of the contact elements of the third group of carrier members in order to obtain an electrical contact between the integrated circuit and the carrier member Consisting of electronic devices
To obtain electrical contact between the active member of the first converter element and the integrated circuit and between the active member of the second converter element and the integrated circuit, at least one of the first group A contact element is electrically connected to at least one contact element of the third group, and at least one contact element of the second group is electrically connected to at least one contact element of the third group. Related to sensor system.
[0024]
The sensor according to the second aspect may be suitable for directivity detection, such as a directional detection pressure transducer.
[0025]
A carrier member such as a Si-based carrier member may further have a second surface that holds a plurality of contact elements. In order to obtain an electrical connection to the second surface, at least one contact element of the first, second and third groups is electrically connected to one of the contact elements held by the second surface. Also good. The first surface and the second surface may be substantially parallel and opposed to each other. Preferably, the transducer element and the electronic device are Si based.
[0026]
The carrier member may further have first and second recesses. The first recess is consistent with the active member of the first transducer element, the second recess is consistent with the active member of second transducer element. The first and second recesses act as a back chamber.
[0027]
Each of the first and second transducer elements may further have a cavity. The bottom of the cavity may be defined by the active members of the first and second transducer elements.
[0028]
For example, to measure pressure changes, each active member of the first and second transducer elements may have a capacitor. This capacitor is formed by a combination of a flexible diaphragm and a substantially rigid back plate. The flexible diaphragm and the substantially rigid back plate may be electrically connected to the contact elements of the respective transducer element.
[0029]
Each of the first and second transducer elements may further have a lid for protecting the transducer elements. The lid and active member of the first and second transducer elements may be arranged to define the upper and lower boundaries of the respective cavities.
[0030]
At least a portion of the outer surface of the sensor system may hold a conductive layer. This conductive layer may be a metal layer or a conductive polymer layer. The contact element may be made of a solder material such as Sn, SnAg, SnAu or SnPb.
[0031]
The solid-state silicon-based condenser microphone according to the present invention is suitable for batch production. The combination of different elements that make up the microphone system is more flexible than other systems disclosed in the prior art. The present invention can provide an interface to a very well defined environment, for example by an opening on one side of the system. This opening can be covered by a film or filter that prevents dust, moisture and other impurities from interfering with and contaminating the microphone characteristics. Electrical connection between the different elements of the microphone system is achieved economically and easily via a silicon carrier using flip-chip technology.
[0032]
The present invention uses integrated electronic circuit chips, preferably ASICs, which may be designed and manufactured independently of the design and manufacture of microphone transducer elements. This is advantageous because the techniques and processes for manufacturing integrated electronic circuit chips are different from those used to manufacture transducer elements and each manufacturing stage is optimized independently. Furthermore, transducer element and ASIC testing may be accomplished at the wafer level.
[0033]
The complete sensor system can be electrically connected to the outside surface by surface mount technology with the contacts facing one side of the system that does not conflict with the aforementioned interface with the environment. Thus, the user can apply a simple and effective surface mounting technique to the assembly of the entire system.
[0034]
(Detailed Description of Embodiments of the Invention)
Hereinafter, the present invention will be further described with reference to the accompanying drawings.
[0035]
The process used to manufacture the different elements of the sensor system requires techniques known in the field of microminiature technology.
[0036]
FIG. 1 shows a silicon carrier substrate 2 that includes one or more vertically etched feedthrough holes 20. The silicon carrier substrate 2 is bulk crystal silicon, and has solder protrusions 8 and 22 on the first surface and the second surface, respectively. The electric signal is conveyed from the first surface to the second surface via the feedthrough line 23. On the first surface, one or a plurality of transducer elements 1 are flip-chip mounted on the silicon carrier substrate 2 and fixed by solder bumps 8 of the first group. On the first surface, one or a plurality of electronic devices such as the integrated circuit chip 3 are flip-chip mounted on the silicon carrier substrate 2 and connected and fixed by the solder protrusions 8 of the second group. The material of the solder bumps 8 is typically Sn, SnAg, SnAu or SnPb, but other metals can also be used.
[0037]
The solder seal ring 9 provides a seal against the transducer element 1. In this case, the feedthrough line 23 is used to carry an electrical signal from the transducer element 1 below the seal ring 9 to the electronic device 3. This is shown in detail in FIG. The signal can also be conveyed to the electronic circuit by other conductive paths.
[0038]
The electrically conductive path 23 is also formed through the carrier, for example by an etching hole 20 and subsequent metallization. Etching can be performed by wet chemical etching or dry plasma etching techniques. This path 23 is called vertical feedthrough and can be used to carry an electrical signal from the transducer 1 or electronic circuit 3 to the second surface of the carrier.
[0039]
The second surface includes solder bumps 22 for surface mounting, for example on a PCB or other carrier.
[0040]
FIG. 2 shows a package similar to that shown in FIG. 1, but in this embodiment the electronic device 3 has a group of solder bumps 8 as well as an underfill or glue 21. Connected and fixed by other means. Furthermore, the package is protected by a lid 5 which is fixed to the flip-chip mounted transducer element 1 or the electronic device 3 or both. The lid 5 has an opening 4 that provides well-determined access to the environment, such as a sound propagation grid or filter, as protection of the microphone against particles and moisture. The lid can be formed separately, for example from metal or polymer, respectively by punching or injection molding.
[0041]
In FIG. 3 or 4, a system applied to a microphone is shown. In these embodiments, the transducer element 1 is a microphone, back lipped Yanba 11 is etched into the silicon substrate 2. The back chamber is etched into the silicon carrier by a wet etching process using reactants such as KOH, TMAH or EDP, or a dry etching process such as reactive ion etching. The cavity 11 can be etched in the same process as the feedthrough hole 20.
[0042]
The difference between FIG. 3 and FIG. 4 is that the system of FIG. 4 is covered with a filter 5 to provide an EMI shield. The EMI shield 16 is a conductive polymer layer, such as silver epoxy, or a metal layer, such as electroplated or evaporated, Cu or Au. Further, the integrated circuit chip 3 and the filter 5 shown in FIG. 4 are connected and fixed by additional means such as underfill or adhesive 21.
[0043]
The functions of the macrophone are as follows. The opening 4 functions as a sound inlet, and ambient sound pressure enters a cavity 10 functioning as a front chamber of the microphone through a filter 5 covering the opening 4. The sound pressure is reflected by the diaphragm 12, whereby the air between the diaphragm 12 and the back plate 13 flows out through the perforations 19.
[0044]
The diaphragm may be manufactured is designed differently. As one example, the diaphragm may be designed as a three-layer structure with two outer layers. The outer layer is made of silicon nitride, while the intermediate layer is made of polycrystalline silicon. The polycrystalline silicon forming the intermediate layer is doped with either boron (B) or phosphorus (P). The back plate is made of B- or P-doped polycrystalline silicon and silicon nitride. The cavity 11 further functions as a microphone back chamber.
[0045]
When the diaphragm 12 is deflected in response to the incident sound pressure, the electric capacity of the electric capacitor formed by the diaphragm 12 and the back plate 13 changes in response to the incident sound pressure. The circuit on the integrated circuit chip 3 is electrically connected to the diaphragm 12 and the back plate 13 via the solder protrusions 8. This circuit is designed to detect changes in the capacitance of the capacitor formed by the diaphragm 12 and the back plate 13. In addition, this circuit is electrically connected to the solder protrusion 22 via the solder protrusion 8 and the vertical feedthrough line 23 in order to be electrically connected to the power supply and other electric circuits in the hearing instrument. .
[0046]
When the capacitor formed by the diaphragm 12 and the back plate 13 is operated, the back plate 13 is connected to a DC power source in order to charge the back plate 13. When the capacitance changes due to a change in the distance between the diaphragm 12 and the back plate 13 in response to the changing sound pressure, an AC voltage is superimposed on the applied DC level. The magnitude of the AC voltage is a measure for the capacitance change and is a magnitude for the sound pressure experienced by the diaphragm.
[0047]
In FIG. 5, the enlargement of the lateral feedthrough line 24 and the seal ring 9 is shown. The feedthrough 24 is electrically insulated from the seal ring 9 and the substrate 2 by the insulating layer 25. Similarly, the insulating layer 25 insulates the solder protrusions 8 of the converter 1 from the substrate 2. The solder projections 8 of the electrical converter 1 and the solder projections 8 of the circuit chip 3 are electrically connected via a feedthrough line 24.
[0048]
In FIG. 6, a microphone similar to that of FIG. 3 is shown. However, the opening 24 is introduced into the back chamber 11. The opening 24 causes membrane deflection, which indicates the pressure gradient of the membrane, and thus the directional sensitivity of the microphone.
[0049]
In FIG. 7, a microphone similar to that of FIG. 3 is shown. However, additional transducer elements are added so that the microphone uses two transducer elements, both of which include a membrane 12 and a backplate 13. Both transducer elements are connected to the carrier member 3 by solder bumps 8 and seal rings 9 and have an indentation 11 for each transducer element. With these two transducer elements, the phase difference of the impact acoustic wave can be measured, and as a result, the directivity sensitivity of the microphone can be measured.
[0050]
It will be apparent to those skilled in the art that the number of detection elements is increased from 2 to any number (as shown in FIG. 7), for example arranged in a matrix.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example in which a silicon-based sensor system is generally applied.
FIG. 2 is a cross-sectional view showing an example in which a silicon-based sensor system having a lid is generally applied.
FIG. 3 is a cross-sectional view showing an example in which a silicon-based sensor system is applied to a microphone.
FIG. 4 is a cross-sectional view showing an application example of an enclosed microphone.
FIG. 5 is an enlarged view of a lateral feedthrough and a seal ring.
FIG. 6 is a cross-sectional view showing an example in which a silicon-based sensor system is applied to a directional microphone.
FIG. 7 is a cross-sectional view showing an example in which a silicon-based sensor system is applied to a second directional microphone.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Converter element 2 Silicon carrier substrate 3 Integrated circuit chip 9 Solder seal ring 8, 22 Solder convex part 23 Feed through line 20 Feed through hole

Claims (26)

A Si-based carrier member (2) having a first surface for holding first and second groups of contact elements;
A transducer element (1) comprising an active member, the active member being electrically connected to at least one contact element;
In a sensor system comprising an electronic device (3) comprising an integrated circuit having at least one contact element,
At least one contact element of the transducer element (1) is used to obtain an electrical contact between the active member of the transducer element (1) and the carrier member (2). ) And one of the contact elements
At least one contact element of the electronic device (3) is used by the transducer element (1) and the electronic device (3) to obtain electrical contact between the integrated circuit and the carrier member. ) Coincides with one of the contact elements of the second group of carrier members (2) so as to be arranged adjacent to the first side of
At least one contact element of the first group is at least one of the second group to obtain electrical contact between the active member of the transducer element (1) and the integrated circuit of the electronic device (3). Electrically connected to one contact element,
The carrier member (2) further has a second surface holding a plurality of contact elements, wherein at least one contact element of the first and second groups is held by the second surface Electrically connected to one of the
The sensor system, wherein the first surface and the second surface are substantially parallel and face each other . Sensor system according to claim 1 , wherein the carrier member (2) further comprises a recess (11), the recess (11) coinciding with the active member of the transducer element. Sensor system according to claim 1 or 2 , wherein the transducer element further comprises a cavity (10), and the active member defines the bottom of the cavity (10). The sensor system according to claim 2 , further comprising an opening (24) between the second surface of the carrier member (2) and the recess (11). Sensor system according to any one of claims 1 to 4 wherein the transducer element (1) is Si-based. The sensor system according to any one of claims 1 to 5 , wherein the carrier member (2), the transducer member (1) and the electronic device (3) are Si-based.   2. A sensor system according to claim 1, wherein the active member of the transducer element comprises a capacitor, the capacitor being formed by a combination of a flexible diaphragm (12) and a substantially rigid back plate (13). Said transducer element (1) further comprises a lid (5), the transducer element (1) of the lid (5) as defined in Claim 3 which defines the boundaries above and below the active member said cavity (10) The sensor system described in. Sensor system according to any one of the sensor at least parts of the conductive layer of the system of the outer surface (16) of claims 1 which holds the 8. The sensor system according to claim 9 , wherein the conductive layer is made of a metal layer. The sensor system according to claim 9 , wherein the conductive layer comprises a conductive polymer layer. Sensor system according to the contact element, Sn, SnAg, any one of claims 1 to 11 consisting of solder material such as SnAu or SnPb. 4. A sensor system according to claim 3 , further comprising sealing means for hermetically sealing the transducer element. A Si-based carrier member having a first surface for holding first, second and third groups of contact elements;
A first transducer element comprising an active member, wherein the active member is electrically connected to at least one contact element;
A second transducer element comprising an active member, the active element being electrically connected to at least one contact element;
In a sensor system comprising an electronic device comprising an integrated circuit having at least one contact element,
At least one contact element of the first transducer element mates with one of the contact elements of the first group of carrier members to obtain electrical contact between the active member and the carrier member;
At least one contact element of the second transducer element is adapted to cause the first transducer element and the second transducer element to be in electrical contact between an active member of the second transducer element and a carrier member. Coincides with one of the contact elements of the second group of carrier members so as to be arranged adjacent to the first side of the carrier member (2);
The at least one contact element of the electronic device is adapted to provide an electrical contact between the integrated circuit and the carrier member so that the electronic device has first and second transducer elements on the first side of the carrier member (2). Coincides with one of the contact elements of the third group of carrier members so as to be disposed adjacent to
To obtain electrical contact between the active member of the first converter element and the integrated circuit and between the active member of the second converter element and the integrated circuit, at least one of the first group A contact element is electrically connected to at least one contact element of the third group, and at least one contact element of the second group is electrically connected to at least one contact element of the third group;
The carrier member (2) further has a second surface holding a plurality of contact elements, wherein at least one contact element of the first and second groups is held by the second surface Electrically connected to one of the
The sensor system, wherein the first surface and the second surface are substantially parallel and face each other . The carrier member further has a second surface for holding a plurality of contact elements, wherein at least one contact element of the first, second and third groups is held by the second surface 15. The sensor system according to claim 14 , wherein the sensor system is electrically connected to one of the two. The sensor system according to claim 15 , wherein the first surface and the second surface are substantially parallel and face each other. The carrier member further has first and second recesses, the first recesses coincide with the active members of the first transducer element, and the second recesses of the second transducer element. 17. A sensor system according to any one of claims 14 to 16 , which is matched with an active member. Having said first and each further cavity of the second transducer element, claim 14 in which the bottom of the cavity is defined by the active members of the first and second transducer elements 17 The sensor system described in. 19. A sensor system according to any of claims 14 to 18 , wherein the first and second transducer elements are Si based. The sensor system according to any of claims 14 to 19 , wherein the carrier member, the first and second transducer members and the electronic device are Si based. Made from the first and each of the active members of the second transducer element capacitor, to claim 14, wherein the capacitor is formed by the combination of the back plate with a flexible diaphragm and a substantially stiff 20 The described sensor system. Having said first and second transducer elements further lid, claims 14 to first and the lid and the active member of second transducer element defines the upper and lower boundary of the respective cavities 21. The sensor system according to any one of 21 . The sensor system according to any one of claims 14 to 22 , wherein at least a part of an outer surface of the sensor system holds a conductive layer. The sensor system according to claim 23 , wherein the conductive layer comprises a metal layer. The sensor system according to claim 23 , wherein the conductive layer comprises a conductive polymer layer. 26. The sensor system according to claim 14 , wherein the contact element is made of a solder material such as Sn, SnAg, SnAu or SnPb.

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