MICROPHONE AND MANUFACTURING METHOD THEREOF

A microphone includes a substrate including an acoustic hole; a supporting layer disposed along a circumference of the substrate; and a vibrating film disposed on the supporting layer and spaced apart from the substrate, wherein the vibrating film includes a first vibrating region positioned at a portion corresponding to the acoustic hole; a second vibrating region connected to the first vibrating region, and including an air inlet; and a third vibrating region connected to the second vibrating region through a plurality of connection parts.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Korean Patent Application No. 10-2016-0113198 filed in the Korean Intellectual Property Office on Sep. 2, 2016, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a microphone, and more particularly, to a microphone capable of minimizing a damping by omitting a fixed film, and a manufacturing method thereof.

BACKGROUND

A microphone is generally a device converting voice into an electrical signal. The microphone should have good electronic and acoustic performance, reliability, and operability. Recently, a demand for a smaller microphone has been increased. Accordingly, a microphone using a micro electro mechanical system (MEMS) technology has been developed.

The MEMS microphone is manufactured using a semiconductor batch process. The MEMS microphone has a tolerance to heat and humidity as compared to a conventional electric condenser microphone (ECM), and may be down-sized and be integrated with a signal processing circuit.

In addition, the MEMS microphone has excellent sensitivity and low performance deviation for each of the products as compared to the conventional ECM. Accordingly, the MEMS microphone has been applied to many application fields instead of the ECM.

The MEMS microphone is generally classified into a piezoelectric MEMS microphone and a capacitive MEMS microphone.

The piezoelectric MEMS microphone includes a vibrating film, and when the vibrating film is deformed by external sound pressure, the electrical signal is generated by a piezoelectric effect to allow the sound pressure to be measured.

The capacitive microphone includes a fixed film and a vibrating film, and when the sound pressure is externally applied to the vibrating film, a capacitance value is changed while an interval between the fixed film and the vibrating film is changed. The sound pressure is measured by an electrical signal generated at this time.

However, since the conventional microphone requires two films such as the vibrating film and the fixed film to configure a parallel capacitor form, a process step thereof is complex. In addition, since a dimple structure should be formed in the vibrating film or the fixed film to prevent a stiction, an additional process is required, which causes a problem that manufacturing costs are increased.

SUMMARY

The present disclosure has been made in an effort to provide a microphone having advantage of removing a fixed film and including only a vibrating film, and a manufacturing method thereof.

Further, the present disclosure has been made in an effort to provide a microphone having advantage of including a slot or a through-hole in one side of a vibrating film, and a manufacturing method thereof.

According to an exemplary embodiment of the present disclosure, a microphone includes: a substrate including an acoustic hole; a supporting layer disposed along a circumference of the substrate; and a vibrating film disposed on the supporting layer and spaced apart from the substrate, wherein the vibrating film includes a first vibrating region positioned at a portion corresponding to the acoustic hole; a second vibrating region connected to the first vibrating region, and including an air inlet; and a third vibrating region connected to the second vibrating region through a plurality of connection parts.

The air inlet may include a first slot positioned between two connection parts; and a plurality of through-holes positioned between the first vibrating region and the first slot.

The air inlet may further include a bending part bent toward the first vibrating region at both end portions of the first slot.

The air inlet may include a second slot positioned between two connection parts.

A width of the first slot may be different from a width of the second slot.

A width of the second slot may be greater than a width of the first slot.

The vibrating film may include a plurality of protrusions protruding on one surface thereof.

An inner circumference surface of the acoustic hole may be formed in an inclined surface.

The acoustic hole may be formed in an inclined surface of which an inner diameter decreases toward the vibrating film.

The microphone may further include a first pad connected to the vibrating film; and a second pad connected to the substrate.

The microphone may further include an insulating layer disposed on the substrate; and an electrode layer disposed on the insulating layer and being in contact with the second pad.

According to another embodiment of the present disclosure, a manufacturing method of a microphone includes: preparing a substrate; forming a sacrificial layer on the substrate; forming a vibrating film on the sacrificial layer; forming a protection layer on the vibrating film; etching the substrate to form an acoustic hole; and etching the sacrificial layer to form a supporting layer along a circumference of the substrate, wherein the vibrating film includes a first vibrating region positioned at a portion corresponding to the acoustic hole; a second vibrating region connected to the first vibrating region, and including an air inlet; and a third vibrating region connected to the second vibrating region through a plurality of connection parts.

According to the embodiments of the present disclosure, since the process step may be reduced by removing the fixed film, the manufacturing costs may be cheaper, and since the damping which may occur in an air layer disposed between the vibrating film and the fixed film may be minimized, frequency response characteristics and noise characteristics may be improved, and an occurrence of a stiction phenomenon may be prevented.

Further, the slot or the through-hole is disposed in one side of the vibrating film, thereby making it possible to maximize displacement of the vibrating film.

Other effects that may be obtained or predicted from the exemplary embodiments of the present disclosure will be explicitly or implicitly disclosed in the detailed description of the exemplary embodiments of the present disclosure. That is, various effects predicted according to the exemplary embodiments of the present disclosure will be disclosed in the detailed description to be described below.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an operation principle of exemplary embodiments of a microphone and a manufacturing method thereof according to the present disclosure will be described in detail with reference to the accompanying drawings and the description. However, the drawings illustrated below and the detailed description to be described below relate to one exemplary embodiment among several exemplary embodiments for effectively describing characteristics of the present disclosure. Therefore, the present disclosure should not be limited to only the following drawings and description.

In addition, in describing the present disclosure, a detailed description for well-known functions or configurations will be omitted in the case in which it is determined that the detailed description may unnecessarily obscure the gist of the present disclosure. In addition, the following terminologies are defined in consideration of the functions in the present disclosure and may be construed in different ways by the intention of users and operators, a custom, or the like. Therefore, the definitions thereof should be construed based on the contents throughout the present disclosure.

In addition, in the following exemplary embodiments, in order to efficiently describe critical technical characteristics of the present disclosure, the terminologies are appropriately deformed, integrated, or separated to be used so that those skilled in the art may clearly understand, but the present disclosure is not necessarily limited thereto.

FIG. 1is a drawing illustrating a microphone according to an exemplary embodiment of the present disclosure,FIG. 2is a drawing illustrating a microphone according to another exemplary embodiment of the present disclosure, andFIG. 3is a drawing illustrating a microphone according to still another exemplary embodiment of the present disclosure.

Referring toFIG. 1, a microphone100according to the present disclosure processes an acoustic signal introduced from the outside and transmits the processed acoustic signal to a processing module (not shown).

That is, the microphone100receives the acoustic signal through an acoustic hole113formed in a substrate110, and is vibrated by sound pressure according to the acoustic signal to transmit a changed capacitance signal to the processing module.

To this end, the microphone100includes the substrate110, a supporting layer125, a vibrating film150, and an insulating film190.

The substrate110includes the acoustic hole113formed in the central portion thereof. The acoustic signal is introduced into the microphone100through the acoustic hole113formed in the substrate110.

The substrate110may serve as the fixed film according to the related art. Accordingly, the microphone100according to the present disclosure vibrates the vibrating film150by the sound pressure to change capacitance between the substrate110and the vibrating film150, and transmits the changed capacitance signal to the processing module through a second pad215connected to the substrate110.

The substrate110may be a heavily doped wafer. In addition, the substrate110may also be formed of silicon.

An inner circumference surface of the acoustic hole113may be perpendicular to an outer surface of the substrate110. A cross section of the acoustic hole113may be formed in a rectangular or square shape, as illustrated inFIG. 1.

Meanwhile, the acoustic hole113may have the inner circumference surface formed in an inclined surface115as illustrated inFIG. 2. The acoustic hole113may have the inclined surface115of which an inner diameter decreases toward the vibrating film150.

An inclination angle (θ) of the inclined surface115may be formed at a set angle with respect to the outer surface of the substrate110. For example, the set angle may be 50° to 60°.

The cross section of the acoustic hole113may be formed in a trapezoidal shape, as illustrated inFIG. 2.

Accordingly, since the inner circumference surface of the acoustic hole113is formed in the inclined surface115, the microphone100according to the present disclosure may collect the acoustic signal and transmit the collected acoustic signal to the vibrating film150.

The supporting layer125is formed on the substrate110. That is, the supporting layer125is formed along a circumference of the substrate, and supports the vibrating film150.

A second contact hole195for exposing the substrate110is formed in the supporting layer125. A second pad215is formed in the second contact hole195.

The second pad215is formed in the second contact hole195, and is connected to the substrate110. The second pad215may be made of a metal.

The vibrating film150is formed on the supporting layer125. The vibrating film150is spaced apart from the substrate110.

An air layer is formed between the substrate110and the vibrating film150. The substrate110and the vibrating film150are spaced apart from each other by a predetermined interval. The acoustic signal is introduced from the outside through the acoustic hole113to stimulate the vibrating film150, by which the vibrating film150is vibrated. In this case, an interval between the substrate110and the vibrating film150is changed. Accordingly, capacitance between the substrate110and the vibrating film150is changed. The capacitance signal changed as described above is output to the processing module through the first pad213connected to the vibrating film150and the second pad215connected to the substrate110.

The vibrating film150includes a plurality of protrusions155formed on one surface thereof. That is, the protrusions155may be formed on a lower surface of the vibrating film150. The protrusions155may prevent the vibrating film150from being in contact with the substrate110when the vibrating film150is vibrated.

The vibrating film150includes a first vibrating region163, a second vibrating region165, and a third vibrating region167. The first vibrating region163is formed to correspond to the acoustic hole113, and the second vibrating region165includes an air inlet180.

The vibrating film150may be formed of polysilicon or a conductive material.

The above-mentioned vibrating film150will be described in detail with reference toFIGS. 4 and 5.

The insulating film190is formed on the vibrating film150. The insulating film190may be formed of silicon nitride.

A first contact hole193for exposing the vibrating film150is formed in the insulating film190. The first pad213is formed in the first contact hole193.

The first pad213is formed in the first contact hole193, and is connected to the vibrating film150. The first pad213may be made of a metal.

The microphone100according to the present disclosure may further include an insulating layer117and an electrode layer119, as illustrated inFIG. 3.

The insulating layer117is formed on the substrate110. That is, the insulating layer117may be formed on the substrate110controlling a portion in which the acoustic hole113is formed. The insulating layer117may be formed of silicon nitride.

The electrode layer119is formed on the insulating layer117, and is formed between the second pad215and the substrate110. That is, the electrode layer119is connected to the second pad215.

The electrode layer119may be formed of polysilicon or a conductive material.

Accordingly, the vibrating film150is vibrated by the sound pressure, and the interval between the electrode layer119and the vibrating film150formed on the substrate110is changed. Accordingly, capacitance between the electrode layer119and the vibrating film150is changed. The capacitance signal changed as described above is output to the processing module through the first pad213connected to the vibrating film150and the second pad215connected to the electrode layer119.

FIG. 4is a plan view illustrating a vibrating film according to an exemplary embodiment of the present disclosure, andFIG. 5is a plan view illustrating a vibrating film according to another exemplary embodiment of the present disclosure.

Referring toFIG. 4, the vibrating film150includes the first vibrating region163, the second vibrating region165, and the third vibrating region167.

The first vibrating region163is formed at a center of the vibrating film150, and is positioned at a portion corresponding to the acoustic hole113formed in the substrate110.

The second vibrating region165is connected to the first vibrating region163, and includes the air inlet180. Since the air inlet180is formed in the second vibrating region165as described above, the microphone100according to the present disclosure concentrates the acoustic signal to the first vibrating region163, thereby making it possible to maximize displacement of the vibration.

The third vibrating region167is connected to the second vibrating region165through a plurality of connection parts170. Since the connection parts170serve as a bridge, the first vibrating region163and the second vibrating region165are vibrated by the sound pressure of the acoustic signal introduced from the outside.

The air inlet180includes a first slot181, a through-hole183, and a bending part185.

The first slot181is formed between the connection part170and the connection part170. That is, the first slot181is formed between the second vibrating region165and the third vibrating region167.

The through-hole183is positioned between the first vibrating region163and the first slot181. A plurality of through-holes183may be formed.

The bending part185is formed to be bent toward the first vibrating region163at both end portions of the first slot181.

The air inlet180further includes a second slot187as illustrated inFIG. 5.

The second slot187is formed between the connection parts170.

A width of the second slot187may be formed to be different from a width of the first slot181. That is, the width of the second slot187may be formed to be greater than the width of the first slot181.

Accordingly, since the entirety of the vibrating film150has a piston type motion, the microphone100according to the present disclosure may obtain a large capacitance change in a limited area, thereby making it possible to improve sensitivity.

In addition, the microphone100according to the present disclosure adjusts an area of the air inlet180, thereby making it possible to adjust sensitivity and noise performance.

A manufacturing method of a microphone according to an exemplary embodiment of the present disclosure will be described with reference toFIGS. 6 to 14.

FIGS. 6 to 14are diagrams sequentially illustrating a manufacturing method of a microphone according to an exemplary embodiment of the present disclosure.

Referring toFIG. 6, a sacrificial layer120is formed on the substrate110.

In other words, in order to form the microphone100, the substrate110is prepared, and the sacrificial layer120is formed on one side of the substrate110. In this case, the substrate110may be formed of silicon, and the sacrificial120may be formed of silicon oxide or silicon nitride.

Referring toFIG. 7, a plurality of depressed parts123are formed in the sacrificial layer120. That is, an upper portion of the sacrificial layer120is etched to form the plurality of depressed parts123.

Referring toFIG. 8, a conductive layer140for forming the vibrating film150is formed on the sacrificial layer120. In this case, a plurality of protrusions155are formed on the conductive layer140so as to be inserted into the plurality of depressed parts123formed in the sacrificial layer120. The conductive layer140may be formed of polysilicon or a conductive material.

Referring toFIG. 9, the insulating film190is formed on the conductive film140, and the conductive layer140is etched to form the vibrating film150.

In other words, the insulating film190formed of silicon nitride is formed on the conductive layer140. In addition, the conductive layer140is etched to form the vibrating film150including the air inlet180. In this case, the insulating film190is also simultaneously etched. The air inlet180is formed in the second vibrating region165of the vibrating film150. The air inlet180includes the first slot181, the through-hole183, and the bending part185as illustrated inFIG. 3, or includes the second slot187as illustrated inFIG. 4.

Referring toFIG. 10, the insulating film190is etched to form the first contact hole193.

That is, a portion of the insulating film190is etched to expose the vibrating film150corresponding to the first contact hole193. In this case, the first contact hole193may be formed at a position corresponding to the third vibrating region167of the vibrating film150.

Referring toFIG. 11, the insulating film190and the sacrificial layer120are etched to form the second contact hole195.

That is, a portion of the insulating film190and the sacrificial layer120is etched to expose the substrate110corresponding to the second contact hole195.

Referring toFIG. 12, the first pad213and the second pad215are formed on the insulating film190.

That is, the first pad213connected to the vibrating film150is formed on the first contact hole193and the insulating film190, and the second pad215connected to the substrate110is formed on the second contact hole195and the insulating film190.

The first pad213and the second pad215may be formed of a metal so as to be electrically connected to the processing module.

Referring toFIG. 13, the substrate110is etched to form the acoustic hole113. The acoustic hole113may be formed in different shape according to an etching method.

That is, the substrate110is wet-etched to form the acoustic hole113including the inclined surface115. The inclined surface115may have an inner diameter which decreases toward the vibrating film150. The acoustic hole113may be formed at a position corresponding to the first vibrating region163of the vibrating film150.

The substrate110is also dry-etched to form the acoustic hole113illustrated inFIG. 1. In this case, an inner circumference surface of the acoustic hole113may be perpendicular to an outer surface of the substrate110.

Referring toFIG. 14, the sacrificial layer120is removed to form the supporting layer125.

That is, a portion of the sacrificial layer120formed on the substrate110is removed to form the supporting layer125along a circumference of the substrate110. In this case, the sacrificial layer120may be removed so that portions of the first vibrating region163, the second vibrating region165, and the third vibrating region167of the vibrating film150are exposed.

As described above, since the microphone100according to the present disclosure may minimize the damping which may occur in the air layer formed between the vibrating film150and the fixed film by removing the fixed film, frequency response characteristics and noise characteristics may be improved, and the process step may be reduced, thereby making it possible to simplify the process.

As described above, since the microphone according to the present disclosure may minimize the damping which may occur in the air layer formed between the vibrating film and the fixed film by removing the fixed film, frequency response characteristics and noise characteristics may be improved, and the process step may be reduced, thereby making it possible to simplify the process.

Hereinabove, although the present disclosure has been described in detail with reference to the exemplary embodiment of the present disclosure, it is to be understood by those skilled in the art that the present disclosure may be variously modified and altered without departing from the scope and spirit of the present disclosure as disclosed in the accompanying claims.