WO2017122954A1

WO2017122954A1 - Microphone and microphone manufacturing method

Info

Publication number: WO2017122954A1
Application number: PCT/KR2016/015440
Authority: WO
Inventors: 공관호; 유인근
Original assignee: (주)글로벌센싱테크놀로지
Priority date: 2016-01-15
Filing date: 2016-12-28
Publication date: 2017-07-20
Also published as: CN108464017B; CN108464017A; KR101711444B1

Abstract

The present invention relates to a microphone and a microphone manufacturing method, the microphone comprising: a membrane including a driving electrode; and a backplate including a fixed electrode, wherein the two electrodes are mechanically connected to a substrate. The microphone manufacturing method of the present invention has effects of enhancing the quality of a microphone manufacturing process and improving the performance of the microphone by improving a structure supporting the backplate and a structure supporting the membrane.

Description

Microphone and microphone manufacturing method

The present invention relates to a microphone and a method of manufacturing a microphone, and more particularly, an electrostatic charge having a membrane vibrating by an external sound pressure and a back plate disposed in parallel with the membrane and charged in electrodes formed on the membrane and the back plate, respectively. A microphone for measuring sound pressure using a change in capacity, and a method for manufacturing the microphone.

Microphones are widely applied to various electronic devices including mobiles, desktops and earsets, and the demand is expected to explode in the future of the Internet of Thing era. In addition, in accordance with the trend toward miniaturization of electronic devices, smaller and cheaper microphones are required. A microphone manufactured by the MEMS (micro electro mechanical system) method is most advantageous as a microphone that meets the market trend. Currently in production, MEMS microphones are mostly capacitive.

An example of an acoustic device having such a capacitive microphone structure is disclosed in Korean Patent Application Laid-Open No. 2011-125584.

Korean Unexamined Patent Publication No. 10-2014-0067238 discloses a method of manufacturing such a microphone. In one of the conventional methods of manufacturing a microphone, a method of forming an electrode by stacking doped polysilicon on an undoped polysilicon to form electrodes on the membrane and the back plate of the microphone, respectively. This method uses a method of stacking two layers of different properties such as undoped-polysilicon and doped-polysilicon, respectively, and etching unnecessary portions. In practice, the process is complicated and inefficient. there was. Due to such a process problem, there was a problem that the manufacturing cost of the microphone is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a method for producing a high quality microphone at a low cost and a relatively simple process, and a microphone manufactured by the method.

In order to solve the problems described above, the present invention, the air gap is disposed between the membrane and the back plate, the sound is detected by using the change in capacitance between the first electrode formed on the membrane and the second electrode formed on the back plate A method of manufacturing a microphone, comprising: (a) forming a first sacrificial layer on an upper surface of a substrate; (b) etching the first sacrificial layer to surround the outer circumference of the region where the membrane is to be formed to form a membrane outer circumference that exposes the surface of the substrate; (c) forming a first silicon layer by laminating undoped polysilicon on an upper surface of the substrate exposed through the membrane outer circumference and an upper surface of the first sacrificial layer; (d) doping a region of the first electrode to be conductive to form the first electrode in the first silicon layer; (e) etching the first silicon layer to form a membrane support for supporting the membrane along an inner circumference of the membrane outer circumference; (f) depositing a second sacrificial layer on the first silicon layer after performing step (e); (g) depositing undoped-polysilicon on the second sacrificial layer to form a second silicon layer; (h) doping the second silicon layer to form a conductive second electrode in the second silicon layer; (i) etching the second silicon layer doped in step (h) to form the second electrode; (j) an outer circumferential portion of the back plate which exposes the surface of the substrate by etching the second sacrificial layer to surround the outer circumference of a region where the back plate is to be formed to form a back plate support portion for supporting the back plate with respect to the substrate; Forming at least two rows; (k) the back plate having a structure in which the second sacrificial layer is disposed between the second sacrificial layer, the back plate outer periphery, and the second electrode to form a support layer, and the second sacrificial layer is disposed between the nitride filled back plate outer periphery; Forming a support; (l) etching the support layer and the second electrode of the plurality of sound hole regions to form a plurality of sound holes in an area surrounded by the outer portion of the back plate; (m) removing a portion of the substrate in the area surrounded by the membrane support at the bottom of the membrane to form a cavity; And (n) removing the first sacrificial layer exposed through the cavity and removing the second sacrificial layer exposed through the sound hole.

In addition, the microphone of the present invention, the substrate; A membrane disposed on the substrate; A membrane support for supporting an outer circumference of the membrane with respect to the substrate; A back plate disposed above the membrane; A back plate support unit supporting an outer circumference of the back plate with respect to the substrate; A second electrode formed on the back plate; And a first electrode formed on the membrane, wherein the back plate support is formed of a structure in which an oxide film is disposed between at least two rows of a nitride film surrounding the outer circumference of the back plate and the nitride film. There is a characteristic.

The microphone and the method of manufacturing a microphone of the present invention have an effect of improving the structure of the back plate supporting structure and the membrane supporting structure to improve the quality of the microphone manufacturing process and the performance of the microphone.

1 to 15 are cross-sectional views illustrating a microphone manufacturing method according to an embodiment of the present invention.

16 is a cutaway perspective view of a microphone manufactured by the microphone manufacturing method illustrated by FIGS. 1 to 15.

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

The microphone manufacturing method according to the present invention is for producing a microphone having a structure as shown in FIG. A membrane support 220 is formed on the substrate 100 to support the membrane 200. The membrane support 220 is firmly fixed to the substrate by the membrane support fixture 503. The first electrode 201 is formed on the membrane 200. The membrane 200 is vibrated by the sound pressure transmitted from the outside. The back plate 300 is disposed above the membrane 200. The backplate 300 is supported relative to the substrate 100 by the backplate support 310. A plurality of sound holes 320 are formed in the back plate 300. External sound pressure is transmitted to the membrane 200 through the sound hole 320 of the back plate 300. The second electrode 301 is formed on the back plate 300. When the membrane 200 vibrates, the distance between the first electrode 201 and the second electrode 301 is changed, and as a result, the capacitance between the first electrode 201 and the second electrode 301 is changed. By using such a change in capacitance, a change in sound pressure may be converted into an electrical signal. Meanwhile, a portion of the substrate 100 is removed below the membrane 200 to form a cavity 101.

Hereinafter, a method of manufacturing a microphone having the structure as described above will be described.

First, as shown in FIG. 1, a first sacrificial layer is formed on the upper surface of the substrate (step (a)). The first sacrificial layer 510 is prepared by depositing an insulating layer oxide film on the silicon wafer substrate 100.

Next, as shown in FIG. 2, a portion of the first sacrificial layer 510 is etched to surround the outer circumference of the region where the membrane 200 is to be formed to form a membrane outer circumference 501 exposing the surface of the substrate (( b) step). The membrane outer periphery 501 is formed by removing the first sacrificial layer 510 at the position where the membrane support 220 supporting the membrane 200 is to be formed to expose the substrate 100. The membrane support 220 is formed on the substrate 100 to form the membrane outer circumference 501 in order to support the membrane 200. In order to form the membrane support part 220 for supporting the membrane 200 to effectively vibrate, the membrane outer periphery 501 is formed in a circular or near circular shape along the circumferential direction.

When the membrane outer peripheral portion 501 is formed as described above, the membrane support groove 502 is also formed. The membrane support groove 502 is formed by etching the first sacrificial layer 510 so that the surface of the substrate is exposed along the inner diameter of the membrane outer circumference 501 to be disposed at a position spaced inwardly with respect to the membrane outer circumference 501. That is, the membrane support groove 502 is formed parallel to the membrane outer peripheral portion 501 along the inner circumference of the membrane outer peripheral portion 501.

In this state, as shown in FIG. 3, the undoped polysilicon is laminated on the upper surface of the substrate 100 and the upper surface of the first sacrificial layer 510 exposed through the membrane outer periphery 501 to form the first silicon layer ( 610 is formed (step (c)). At this time, the undoped polysilicon is also laminated to the membrane support groove 502. As such, the undoped polysilicon is laminated to form a membrane support fixing part 503 made of the first sacrificial layer 510 between the membrane outer peripheral part 501 and the membrane support groove 502. The first silicon layer 610 constitutes the membrane 200, the membrane support 220, and the membrane support fixing part 503.

Next, as shown in FIG. 4, the region of the first electrode 201 is doped to form the first electrode 201 on the first silicon layer 610 (step (d)). In the present embodiment, the first silicon layer 610 is doped by ion implantation. As a result of the doping, the first silicon layer 610 at the position where the first electrode 201 is to be formed becomes conductive. As described above, when the region of the first electrode 201 is doped, the region of the electrode pad is also doped. The electrode pad is formed to be able to be connected to an external circuit by wire bonding in the future.

Next, as shown in FIG. 5, the first silicon layer 610 is etched to form a membrane support part 220 supporting the membrane 200 at positions of the membrane 200 and the membrane outer peripheral part 501 ((e) ) step). That is, the remaining regions of the first silicon layer 610 except for the region to be the membrane 200, the membrane support 220, and the electrode pad 401 are removed by etching. By this process, the structure constituting the membrane 200 is completed. The membrane 200 is disposed at a height apart from the substrate and a membrane support 220 is connected along an edge thereof to support the membrane 200 with respect to the substrate.

Next, as illustrated in FIG. 6, the second sacrificial layer 520 is stacked on the first silicon layer 610 (step (f)). The second sacrificial layer 520 constitutes an air gap 420 between the membrane 200 and the back plate 300. The second sacrificial layer 520 is formed by stacking oxide films.

Next, as shown in FIG. 7, the undoped polysilicon is laminated on the second sacrificial layer 520 to form the second silicon layer 620 (step (g)).

The second silicon layer 620 formed in step (g) is doped to have conductivity, thereby preparing to form the second electrode 301 (step (h)). Like the first silicon layer 610 described above, the second silicon layer 620 is formed by stacking undoped polysilicon to form the second electrode 301 and doped by ion implantation to make it conductive. .

In this state, as shown in FIG. 8, the second silicon at the position 331 where the dimple 330 is to be formed to form the dimple 330 that prevents the back plate 300 from contacting the membrane 200. A portion of the layer 620 and the second sacrificial layer 520 are etched (step (o)). The dimple 330 is an insulating structure formed on the back plate 300 to protrude toward the first electrode 201. The membrane 200 vibrates greatly during the use of the microphone so that the first electrode 201 is prevented from contacting the second electrode 301.

Next, as shown in FIG. 9, the second silicon layer 620 doped in step (g) is etched to form a second electrode 301 (step (i)).

As described above, when the structure of the second electrode 301 is completed, the structure for supporting the second electrode 301 is provided to complete the back plate 300.

First, as shown in FIG. 10, in order to form the back plate support part 310 that supports the back plate 300 with respect to the substrate 100, the second sacrificial material surrounds the outer circumference of the region where the back plate 300 is to be formed. The layer 520 is etched to form two rows of back plate outer peripheries 311 exposing the surface of the substrate 100 (step (j)). The second sacrificial layer 520 is etched so as to surround the membrane 200 and the back plate 300 at a position relatively farther than the membrane support 220 to expose the substrate 100 positioned below the second sacrificial layer 520. As such, by etching the second sacrificial layer 520 to the depth at which the substrate 100 is exposed, the back plate support part 310 capable of supporting the back plate 300 with respect to the substrate 100 may be prepared. do.

In this state, as shown in FIG. 11, a nitride is deposited to provide a backing layer support part 310 and a backing plate 300 to form a backing layer 701 (step (k)). In this case, the dimple 330 is formed by depositing nitride in the region etched in step (o). In this way, by forming the back plate 300 and the back plate support part 310 by the support layer 701 formed by the nitride structure, the second electrode 301 can be effectively fixed and supported while being insulated from the substrate 100. There is an advantage. In particular, the back plate 300 may be stably supported by the back plate support 310 having a structure in which a second sacrificial layer is filled between outer portions of the back plate outer periphery 311 filled with nitride. In addition, due to the structure of the back plate outer periphery 311 and the second sacrificial layer 520 disposed therebetween, which has an insulating property and excellent selectivity with respect to the sacrificial layer, the space between the back plate 300 and the membrane 200 is later formed. When performing the process of removing the second sacrificial layer 520, the configuration outside the back plate support 310 has an advantage that can be stably preserved without being affected.

Next, a process of forming

electrode pads

401 and 402 for connecting the first electrode 201 and the second electrode 301 with an external circuit will be described.

First, as shown in FIG. 12, a portion of the support layer 701 or the support layer 701 and the second sacrificial layer 520 is etched to form the first silicon layer 610 in the region where the

electrode pads

401 and 402 are to be formed, respectively. And exposing the second silicon layer 620 (step (p)). By etching a portion of the support layer 701 and the second sacrificial layer 520 to expose a portion of the first silicon layer 610 to provide a region in which the electrode pad 401 to be connected to the first electrode 201 is formed. do. In the case of the electrode pad 402 connected to the second electrode 301, only a portion of the support layer 701 is etched.

Next, as illustrated in FIG. 12, the metal layers for forming the

electrode pads

401 and 402 are stacked and then etched to be electrically connected to the first electrode 201 and the second electrode 301. 402 is formed respectively (step (q)).

Next, a process of forming the sound hole 320 will be described with reference to FIG. 13. As illustrated in FIG. 13, the support layer 701 and the second electrode 301 are etched at a plurality of points within the area surrounded by the back plate support 310 to form the sound hole 320 ((l) ) step). As described above, the external sound pressure is transmitted to the membrane 200 inside the back plate 300 through the sound hole 320.

After the acoustic hole 320 is formed as described above, as shown in FIG. 14, the cavity 101 is removed by removing a portion of the substrate 100 in the area surrounded by the membrane support parts 220 below the membrane 200. (Step (m)). The cavity 101 formed by etching the rear surface of the substrate 100 serves as a back chamber of the microphone.

Next, as shown in FIG. 15, the first sacrificial layer 510 and the second sacrificial layer 520 are removed through an etching process to make the membrane 200 vibrate ((n) step. ). As the second sacrificial layer 520 is removed, an air gap 420 is formed between the first electrode 201 and the second electrode 301, and the dimple 330 penetrating the second electrode 301 is the first electrode. Exposed to protrude toward 201. On the other hand, as described above, by forming the support layer 701 using the nitride having excellent selectivity with respect to the sacrificial layer, a chamber surrounded by the support layer 701 is formed, and the membrane 200 is disposed therein. . Since the support layer 701 surrounds the inner space of the chamber, there is an advantage in that other components of the surroundings are prevented from being etched in the process of removing the first sacrificial layer 510 and the second sacrificial layer 520. Due to the configuration of the nitride support layer 701 there is an advantage that can improve the process yield.

In addition, in the present embodiment, there is no concern that impurities of the second electrode 301 may diffuse into the support layer 701 during the heat treatment process. For this reason, the method for manufacturing a microphone according to the present invention has an advantage of improving yield and improving product quality.

Meanwhile, as described above, in step (b), the membrane support groove 502 is formed, and in step (c), the undoped-polysilicon is also laminated to the membrane support groove 502 so that the membrane outer peripheral portion 501 and the membrane support groove are formed. By constructing the membrane support part 220 in which the membrane support fixing part 503 is formed between the 502, there is an advantage that the membrane 200 can be more stably supported with respect to the substrate 100.

As mentioned above, although the preferable example was demonstrated about the microphone manufacturing method which concerns on this invention, the scope of the present invention is not limited to the case mentioned above.

For example, the case in which the dimple 330 is formed to prevent contact between the first electrode 201 and the second electrode 301 has been described as an example. However, in some cases, the dimple may not be configured. It is possible.

In addition, the structure of the membrane 200 and the back plate 300 may be variously modified.

In addition, although the support layer 701 has been described as being formed by depositing nitride, it is also possible to configure the support layer using another insulating material.

On the other hand, the microphone of the present invention has the same structure as the microphone manufactured by the microphone manufacturing method described above.

As described above, the back plate support part 310 having a two-row structure has a structure in which an insulating layer oxide film is disposed between nitride films. That is, the back plate support 310 is formed such that the back plate support 310 surrounds the outer circumference of the back plate 300 in a state where two rows of nitride films cover the insulating layer oxide film deposited on the substrate 100. . Even if the second sacrificial layer 520 is removed and the air gap 420 is formed by the structure, the back plate 300 may be effectively prevented from being etched or damaged in other components around the back plate support 310. ) Can secure a structure that can support () stably.

In addition, as described above, the membrane support fixing part 503 formed of an oxide film is formed on the outer side of the membrane supporting groove 502 and the outer periphery of the membrane 200 is covered with the nitride support covering the membrane supporting fixing part 503. By constituting the membrane support unit 220 in a supporting structure, the membrane support unit 220 may have a structure capable of stably supporting the membrane 200. In particular, such a structure of the membrane support 220 has an advantage of improving the durability of the microphone by dispersing or offsetting internal stress that may be caused by the membrane 200 or the peripheral structure of the membrane support 220. .

Claims

An air gap is disposed between a membrane and a back plate, and a method of manufacturing a microphone for detecting sound by using a change in capacitance between a first electrode formed on the membrane and a second electrode formed on the back plate,

(a) forming a first sacrificial layer on an upper surface of the substrate;

(b) etching the first sacrificial layer to surround the outer circumference of the region where the membrane is to be formed to form a membrane outer circumference that exposes the surface of the substrate;

(c) forming a first silicon layer by laminating undoped polysilicon on an upper surface of the substrate exposed through the membrane outer circumference and an upper surface of the first sacrificial layer;

(d) doping a region of the first electrode to be conductive to form the first electrode in the first silicon layer;

(e) etching the first silicon layer to form a membrane support for supporting the membrane along an inner circumference of the membrane outer circumference;

(f) depositing a second sacrificial layer on the first silicon layer after performing step (e);

(g) depositing undoped-polysilicon on the second sacrificial layer to form a second silicon layer;

(h) doping the second silicon layer to form a conductive second electrode in the second silicon layer;

(i) etching the second silicon layer doped in step (h) to form the second electrode;

(j) an outer circumferential portion of the back plate which exposes the surface of the substrate by etching the second sacrificial layer to surround the outer circumference of a region where the back plate is to be formed to form a back plate support portion for supporting the back plate with respect to the substrate; Forming at least two rows;

(k) the back plate having a structure in which the second sacrificial layer is disposed between the second sacrificial layer, the back plate outer periphery, and the second electrode to form a support layer, and the second sacrificial layer is disposed between the nitride filled back plate outer periphery; Forming a support;

(l) etching the support layer and the second electrode of the plurality of sound hole regions to form a plurality of sound holes in an area surrounded by the outer portion of the back plate;

(m) removing a portion of the substrate in the area surrounded by the membrane support at the bottom of the membrane to form a cavity; And

(n) removing the first sacrificial layer exposed through the cavity and removing the second sacrificial layer exposed through the sound hole.
The method of claim 1,

When the step (b) is performed, the first sacrificial layer is etched so that the surface of the substrate is exposed along the inner diameter of the membrane outer circumference to be disposed at a position spaced inwardly with respect to the membrane outer circumference to form a membrane support groove together. and,

When the step (c) is performed, the undoped polysilicon is also laminated to the membrane support groove so that a membrane support fixing part formed of the first sacrificial layer is formed between the outer periphery of the membrane and the membrane support groove.

And etching the first silicon layer in the step (e), wherein the membrane support fixing part remains inside the membrane support part to fix the membrane support part to the substrate.
The method of claim 2,

(p) forming the support layer by depositing the nitride by the step (k), and then etching the support layer or a portion of the support layer and the second sacrificial layer to respectively form the first silicon layer in the region where the electrode pad is to be formed. And exposing a second silicon layer; And

(q) stacking a metal layer for forming the electrode pad to form an electrode pad electrically connected to the first electrode and the second electrode;
Board;

A membrane disposed on the substrate;

A membrane support for supporting an outer circumference of the membrane with respect to the substrate;

A back plate disposed above the membrane;

The oxide film is etched in at least two rows of oxide films stacked on the outer circumference of the back plate with respect to the substrate, and the oxide is deposited between at least two rows of nitride films covering the outer circumference of the back plate by depositing nitride. A back plate support formed in a structure disposed;

A second electrode formed on the back plate; And

And a first electrode formed on the membrane.
The method of claim 4, wherein

The membrane support part may be a nitride film supporting the membrane support fixing part of an oxide film deposited on the upper surface of the substrate along the outer circumference of the membrane and the membrane supporting fixing part along the outer circumference of the membrane while covering the membrane supporting fixing part with respect to the substrate. Microphone composed.