KR100409273B1 - A chip microphone - Google Patents

Abstract

According to the present invention, it is possible to have an acoustic part in which a pair of metal thin films including a diaphragm having an air gap are integrally formed at a predetermined interval on a silicon wafer in which a field effect transistor and a pair of capacitors are integrated. Since a microphone can be produced and a pair of capacitors are connected to the output terminal of the field effect transistor in parallel with each other, the wide frequency band characteristic makes it compatible with CDMA and GSM cell phones, and also the field effect on the silicon wafer. Since the transistor and the pair of capacitors are integrated, the manufacturing cost can be reduced, and the surface mounting apparatus can be soldered to the printed circuit board.

Description

Chip microphone {A CHIP MICROPHONE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip microphone, and in particular, a diaphragm is formed by maintaining a predetermined thickness of a metal thin film (metal layer) on a silicon wafer so as to be grounded through a source electrode of a field effect transistor, and acting as a diaphragm. The capacitor is connected to the drain electrode of the field effect transistor on the lower metal layer deposited under the metal layer so that the positive voltage is fixedly applied, thereby forming a capacitor having a predetermined capacity between the upper metal layer and the lower metal layer. The present invention relates to a chip microphone capable of amplifying a field effect transistor using a change in voltage according to the change as an input signal.

This type of electret condenser microphone, which is widely used in the related art, is disclosed in Korean Utility Model Registration Publication No. 20-2001-218653, filed with Utility Model Registration on November 1, 2000, and published on April 2, 2001. have.

The electret condenser microphone disclosed in the publication is vibrated by the sound pressure introduced through the case 50 and the sound holes 52 of the case 50 as shown in detail in FIGS. 1 to 4. A diaphragm 70 for converting the electric signal into an electrical signal, and a plurality of small sound holes 82a on the bottom surface of the concave portion 82 so that the diaphragm 70 vibrates easily. The semiconductor wafer 80, the integrated circuit 100 for receiving and amplifying the electrical signal converted by the diaphragm 70, and the opening formed in the upper portion of the case 50 are covered with the semiconductor wafer ( The insulating cap 110 electrically insulating the case 50 from the insulating cap 110 and the contact cap 102 electrically connected to the integrated circuit 100 via a lead wire 102a. A contact pin 120 installed on the 110 and the insulation; The signal amplified in the integrated circuit 100 deposited on the semiconductor wafer 80 and deposited on the semiconductor wafer 80 is electrically connected to the contact element 103 connected to the integrated circuit 100 via a lead wire 102b. The contact pin 130 is provided on the insulating cap 110 to be electrically connected to the outside.

In other words, the case 50 of the conventional electret condenser microphone has an opening formed at an upper portion thereof, and a plurality of sound holes 52 are formed and electrically grounded to collect and pass sound at the center thereof. The diaphragm 70 has a predetermined gap Δt inside the case 50 so as to be vibrated by the sound pressure introduced through the sound hole 52 of the case 50 to convert the sound signal into an electrical signal. It is provided in parallel with the bottom inner surface 50a of 50. As shown in FIG.

The diaphragm 70 includes an electret film 72 in which charge is charged, a conductive film 74 formed by sputtering or chemical vapor growth of a metal on one side of the electret film 72, and the electret film 72. Conductive film 74 formed in the polar ring 76 disposed on the lower edge of the conductive film 74 so as to be located at a predetermined distance (△ t) from the bottom inner surface (50a) of the case 50 have.

However, the conventional electret condenser microphone, which is configured as described above, is composed of a plurality of independent parts assembled, and there is a problem such as providing a cause of noise when it is mounted on a communication device, and when it is reduced in size, acoustic There is a problem in that the ultra-slim can not be achieved because there is a limit in the general characteristics.

In addition, in the conventional electret condenser microphone, since the semiconductor wafer 80 and the diaphragm 70 are composed of separate components, not only the workability is poor and the manufacturing cost is increased, but also the electret at the high temperature of 260 ° C. or higher is used. Since electrons are emitted and the sensitivity is lowered, there is also a problem such that soldering to a printed circuit board such as a mobile phone is impossible due to a surface mounting device.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a microchip (light and thin) chip in which a metal thin film is integrally formed at a predetermined interval on a silicon wafer in which a field effect transistor and a pair of capacitors are integrated. To provide a microphone.

Another object of the present invention is to provide a chip microphone having a wide frequency band characteristic.

Still another object of the present invention is to provide a chip microphone that can be used interchangeably with a CDMA and GSM mobile phone.

Another object of the present invention is to provide a chip microphone which can reduce the manufacturing cost.

Another object of the present invention is to provide a chip microphone that can be soldered to a printed circuit board by a surface mount device.

In order to achieve the above object, a chip microphone according to an embodiment of the present invention includes a silicon wafer acting as a gate electrode, a field effect transistor integrated on the silicon wafer, and amplifying sound pressure to a predetermined level, and the field effect transistor. The silicon wafer to electrically connect the pair of capacitors electrically connected to each other in parallel with each other in order to receive the amplified signal outputted from the filter, the drain electrode and the source electrode of the field effect transistor, and to electrically connect the pair of capacitors. A metal wiring deposited by sputtering on the insulating layer, an insulating layer deposited to electrically insulate an upper surface of the silicon wafer, and a metal deposited on a center portion of the insulating layer and connected to the drain electrode of the field effect transistor. A lower metal layer deposited by A silicon oxide layer deposited on the silicon nitride layer and the lower metal layer of the insulating layer, an upper metal layer deposited on the center of the silicon oxide layer and having a plurality of acoustic holes formed therein, and connected to the source electrode of the field effect transistor; And an air gap formed by removing a portion of the silicon oxide layer deposited on the lower portion of the upper metal layer by etching.

1 is a perspective view schematically showing a conventional electret condenser microphone;

2 is a partial longitudinal cross-sectional view partially cut away from FIG.

3 is a perspective view schematically showing the diaphragm applied to FIG. 1, FIG. 4 is a perspective view specifically showing a semiconductor wafer in which the IC circuit of FIG. 2 is integrated;

5 is a plan view schematically showing a chip microphone according to an embodiment of the present invention;

6 is a cross-sectional view along arrow A-A in FIG. 4;

7 is an arrow B-B cross-sectional view in FIG. 4;

FIG. 8 is a cross-sectional view taken along the arrow C-C in FIG. 4.

<Description of Symbols for Main Parts of Drawings>

1: silicon wafer 4: silicon oxide

5: Silicon nitride layer 8a, 8b: Metal terminal

9: metal electrode 10: lower metal layer

11: Silicon oxide layer 13: Upper metal layer

13a: acoustic hole 15: air gap

Q1: Field effect transistors C1, C2: Capacitor

Hereinafter, a chip microphone according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 is a plan view schematically showing a chip microphone according to an embodiment of the present invention, FIG. 6 is a cross-sectional view taken along arrow AA in FIG. 5, FIG. 7 is a cross-sectional view taken along arrow BB in FIG. 5, and FIG. 8 is shown in FIG. 5. Arrow CC sectional drawing in FIG.

As shown in FIGS. 5 to 8, a chip microphone according to an embodiment of the present invention has a field effect transistor Q1 that amplifies sound pressure to a predetermined level on a silicon wafer 1 serving as a gate electrode. At the same time, a pair is provided at the output terminal of the field effect transistor Q1 so that the amplified signal output from the field effect transistor Q1 is received and the noise is filtered, and the CDMA and GSM cell phones are compatible. Capacitors C1 and C2 are connected in parallel with each other.

On the silicon wafer 1, the drain electrode D and the source electrode S of the field effect transistor Q1 are electrically connected to each other, and a pair of capacitors C1 and C2 are electrically connected to each other. The wiring 2 is deposited by the vapor deposition method.

In the chip microphone of the present invention, the silicon oxide (SiO ₂ ) layer 4 and the silicon nitride (Si ₃ N ₄ ) layer 5 are sequentially deposited to electrically insulate the upper surface of the silicon wafer 1. And the drain electrode D and the source electrode S so as to electrically connect the drain electrode D and the source electrode S of the field effect transistor Q1 deposited on the silicon wafer 1, respectively. And partially remove the silicon oxide (SiO ₂ ) layer 4 and the silicon nitride layer 5 deposited on the metal layer 8 by etching to deposit the metal terminals 8a and 8b by the deposition method, and at the same time, the silicon nitride layer Also on (5), the lower metal layer 10 is deposited by the vapor deposition method.

The silicon oxide layer (5) is disposed on the silicon nitride layer 5 and the lower metal layer 10 removed by etching, leaving the center portion, which is a necessary part of the lower metal layer 10, removed by etching. SiO ₂ ) 11 is deposited, and upper portions of the metal terminals 8a and 8b of the silicon oxide layer 11 are removed by etching, and then metal is deposited by vapor deposition to deposit the metal electrodes 9a and 9b and the diaphragm. The upper metal layer 13 to be used is simultaneously formed and electrically connected to the metal terminals 8a and 8b.

A metal electrode 9 is deposited along both edges of the silicon oxide layer 11 by removing a predetermined width by etching to electrically connect the metal terminals 8a and 8b.

An upper metal layer 13 of a metal material in which a plurality of sound holes 13a are formed by etching is deposited in the center of the silicon oxide layer 11, and an etching solution is formed through the sound holes 13a formed in the upper metal layer 13. Is injected to remove the silicon oxide layer 11 between the upper metal layer 13 and the lower metal layer 10 by etching to form an air gap 15.

The upper metal layer 13 is preferably deposited with a metal, but in consideration of manufacturing cost, manufacturing process, conductivity, and characteristics of the diaphragm, aluminum, chromium, and the like are selected from metals of other materials having characteristics as diaphragms. It is preferable.

The upper metal layer 13 constitutes a diaphragm, and the thickness of the upper metal layer 13 is preferably 0.01 to 10 μm, and the upper metal layer 13 is formed by depositing metal so that an electric field is formed when an external power source is supplied. Is deposited.

In the above description, the source electrode S of the field effect transistor Q1 is electrically connected to the metal layer 13 and grounded, and the drain electrode D of the field effect transistor Q1 is supplied with + power. Although the present invention is described with reference to the lower metal layer 10 as an example, the present invention is not limited thereto. For example, the source electrode S of the field effect transistor Q1 is connected to the lower metal layer 10. The drain electrode D of the field effect transistor Q1 is electrically connected to the upper metal layer 13, and the design change is included in the concept of the present invention.

Next, the operation and effect on the chip microphone according to the embodiment of the present invention configured as described above will be described.

The field effect transistor Q1 and a pair of capacitors C1 and C2 are integrated on the silicon wafer 1 serving as a gate electrode, and the metal electrode (1) is disposed on the air gap 15 of the silicon wafer 1. Since the upper metal layer 13 serving as a diaphragm having a thickness of 0.01 to 10 μm via 9a and 9b is provided on the air gap 15, the upper metal layer 13 is formed by the negative pressure introduced into the upper metal layer 13. It vibrates smoothly.

In addition, a portion of the silicon oxide layer 11 deposited between the upper metal layer 13 and the lower metal layer 10 constituting the diaphragm is removed by etching to form an air gap 15, and the air gap 15 is formed. Since the electric field is supplied from the outside through the upper metal layer 13 and the lower metal layer 10 formed at the upper and lower portions of the c), it is not necessary to charge the upper metal layer 13 with electrons. Since the upper metal layer 13 is connected to the source terminal of the field effect transistor Q1 and the lower metal layer 10 is connected to the drain terminal, a separate additional power source is formed to form an electric field between these two metal layers 10 and 13. It is one of the advantages of the present invention to distribute and use the power supplied to drive the field effect transistor Q1 without the need for a device.

The chip microphone according to the present invention integrates the upper and lower metal layers 10 and 13 which form an acoustic portion at a predetermined interval on the silicon wafer 1 in which the field effect transistor Q1 and the pair of capacitors C1 and C2 are integrated. The chip microphone can be miniaturized (light and small), and a pair of capacitors C1 and C2 are connected in parallel to filter noise at the output terminal of the field effect transistor Q1, so that the frequency band characteristics are wide. It is compatible with CDMA and GSM mobile phones.

In the chip microphone according to the present invention, the field effect transistor Q1 and the pair of capacitors C1 and C2 are integrally integrated on the silicon wafer 1, and the silicon oxide layer ( Since a part of 11) is removed by etching to form the air gap 15, the manufacturing cost can be reduced, and since there are no electrons to be released by heat during soldering, the surface mounting device Therefore, even when soldering a printed circuit board, the characteristics of the chip microphone are maintained.

In the above description, the deposition of the silicon oxide layer 11 and the lower metal layer 10 on the silicon nitride layer 5 has been described as an example, but the present invention is not limited thereto. For example, the silicon oxide layer 11 Instead, the photoresist layer or the selected other metal sacrificial layer may be included in the concept of the present invention.

In the above description, the specific embodiments have been shown and described, but the present invention is not limited thereto, for example, by those skilled in the art without departing from the concept of the present invention. Of course, the design can be changed in various ways.

As described above, according to the chip microphone according to the present invention, an acoustic part integrally formed with a pair of metal thin films including a diaphragm having an air gap at a predetermined interval on a silicon wafer in which a field effect transistor and a pair of capacitors are integrated. It can be used to produce ultra-small (small and thin) chip microphones, and because a pair of capacitors are connected to the output of the field effect transistor in parallel with each other, the frequency band characteristics are wide so that they can be used interchangeably with CDMA and GSM mobile phones. In addition, since the field effect transistor and the pair of capacitors are integrated on the silicon wafer, the manufacturing cost can be reduced, and the surface mounting device can be soldered to the printed circuit board.

Claims (8)

A silicon wafer 1 serving as a gate electrode, a field effect transistor Q1 integrated on the silicon wafer 1 and amplifying sound pressure to a predetermined level, and an amplified signal output from the field effect transistor Q1 A pair of capacitors (C1, C2) connected in parallel to each other to filter the noise, the drain electrode (D) and the source electrode (S) of the field effect transistor (Q1) are electrically connected, and a pair of An insulating layer deposited to electrically insulate the upper surface of the silicon wafer 1 from the metal wirings 2 deposited by the evaporation method on the silicon wafer 1 so as to electrically connect the capacitors C1 and C2. And a lower metal layer 10 deposited on a center portion of the insulating layer and deposited by depositing a metal so as to be connected to the drain electrode of the field effect transistor Q1, and a silicon nitride layer 5 and a lower metal layer of the insulating layer ( The upper metal layer deposited on the silicon oxide layer 11 deposited on the layer 10 and the central portion of the silicon oxide layer 11 and formed with a plurality of sound holes 13a and connected to the source electrode of the field effect transistor. (13) and an air gap (15) formed by etching a portion of the silicon oxide layer (11) deposited under the upper metal layer (13). The chip microphone according to claim 1, wherein the upper metal layer (13) constitutes a diaphragm, and an acoustic hole (13a) is formed in the upper metal layer (13). The chip microphone according to claim 2, wherein the upper metal layer (13) has a thickness of 0.01 to 10 mu m. The chip microphone according to claim 2, wherein the upper metal layer (13) is formed by depositing a metal by a vapor deposition method. The chip microphone according to claim 1, wherein the insulating layer is made of a silicon oxide layer (4) and a silicon nitride layer (5). The chip microphone according to claim 1, wherein the air gap (15) has a thickness of 0.01 to 10 mu m. 2. The source electrode (S) of the field effect transistor (Q1) is electrically connected to the upper metal layer (13) and grounded, and the drain electrode (D) of the field effect transistor (Q1) has a positive power supply. Chip microphone, characterized in that it is electrically connected with the lower metal layer (10) so that it is applied. The method of claim 1, wherein the source electrode (S) of the field effect transistor (Q1) is electrically connected to the metal layer 10, the drain electrode (D) of the field effect transistor (Q1) is the upper metal layer (13). And a chip microphone which is electrically connected to the chip.