KR20140064005A

KR20140064005A - Membrane vibration apparatus and method for manufacturing there of

Info

Publication number: KR20140064005A
Application number: KR1020120130826A
Authority: KR
Inventors: 송호영; 정민주
Original assignee: (주)와이앤지; 정민주
Priority date: 2012-11-19
Filing date: 2012-11-19
Publication date: 2014-05-28

Abstract

The present invention relates to a vibration energy conversion device comprising a substrate on which a through hole is formed, a membrane formed on a first surface of the substrate to cover the through hole, a vibration energy conversion device formed on one surface of the membrane, And a calibration mass formed on the other surface of the membrane, and a method of manufacturing the same, wherein external vibration energy can be efficiently converted into electric energy.

Description

[0001] MEMBRANE VIBRATION APPARATUS AND METHOD FOR MANUFACTURING THERE OF [0002]

The present invention relates to a membrane vibration apparatus and a method of manufacturing the same.

Microphones are largely divided into resistance type, condenser type and piezoelectric type. Resistance type microphones use the principle that the resistance changes when they are subjected to vibration, and the resistance value changes according to the ambient temperature change. In a condenser type microphone having excellent frequency characteristics, one pole of the capacitor is fixed and the other pole acts as a diaphragm. When the diaphragm is vibrated by the movement of air molecules in the microphones, the distance between the diaphragm and the fixed one pole changes and the capacitance changes, resulting in a voltage. In the case of such a condenser-type microphone, there is a disadvantage that a DC voltage must always be applied between the positive and negative electrodes in order to cause a change in capacitance. Piezoelectric microphones use piezo effects in which a potential difference is generated across a piezoelectric material when physical pressure is applied to the piezoelectric material.

The piezoelectric microphones include a membrane vibration device including a MEMS element having a piezoelectric material formed on a substrate. This membrane vibration device converts the external vibration energy into electric energy and transmits it to the microphones.

1A and 1B, a general membrane vibration device 100 includes a substrate 110 having a through hole 150 formed thereon, an oxide film 120 formed on one surface of the substrate 110 and the through hole 150, A lower electrode 142 and an upper electrode 146 formed separately on the nitride film 130 and a piezoelectric film 144 formed between the lower electrode 142 and the upper electrode 146.

The oxide film 120 and the nitride film 130 constitute a membrane 125. The nitride film 130 has a shape of Si _X N _Y and the piezoelectric film 150 is a zinc oxide film ZnO. The piezoelectric film 144 serves to convert external vibration energy into electric energy. The lower electrode 142, the piezoelectric film 144, and the upper electrode 146 constitute a vibration energy conversion device 140.

A conventional membrane vibrator has a problem in that efficiency is lowered in the process of converting external vibration energy into electric energy.

In order to solve the above-described problems, the present invention aims to provide a membrane vibration device that efficiently converts external vibration energy into electric energy and a method of manufacturing the same.

The present invention relates to a vibration energy converting apparatus comprising a substrate having a through hole formed therein, a membrane formed on one surface of the substrate so as to cover the through hole, a vibration element formed on one surface of the membrane, The present invention relates to a membrane vibration device including a calibration mass formed on the other surface of a membrane, and efficiently transmits vibration energy through mass control of the correction mass.

Forming a membrane on one side of the substrate; forming a vibration energy conversion device on the one side of the membrane, the piezoelectric device including a piezoelectric element between two electrodes; A step of depositing a photoresist on the other surface of the substrate so as to correspond to the following through holes and a calibration mass and the through hole exposing the bottom surface of the membrane by etching the substrate, And forming the correction mass on the bottom surface of the membrane vibrating device.

The present invention provides a membrane vibration device in which a correction mass is combined with a membrane and a method of manufacturing the same, so that electric energy can be effectively generated even with a small external vibration energy.

1A is a cross-sectional view of a general membrane vibration device.
1B is a perspective view showing a bottom surface of a general membrane vibration device.
2A is a cross-sectional view of a membrane vibration device according to an embodiment of the present invention.
2B is a perspective view of a portion of a bottom surface of the membrane vibration device according to an embodiment of the present invention.
3A to 3I are cross-sectional views illustrating a method of manufacturing a membrane vibration apparatus according to another embodiment of the present invention.
4 is a cross-sectional view of a membrane vibration device according to another embodiment of the present invention.
5 is a cross-sectional view of a membrane vibration device according to another embodiment of the present invention.
6A and 6B are cross-sectional views of a membrane vibration device according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected to or connected to the other component, It should be understood that an element may be "connected," "coupled," or "connected."

Hereinafter, a membrane vibration apparatus and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of the layers or regions shown in the figures are exaggerated for clarity of the description.

2A is a cross-sectional view of a membrane vibration device according to an embodiment of the present invention.

The membrane vibration apparatus 200 according to an embodiment of the present invention includes a substrate 210, a through hole 230, a correction mass 220, oxide films 240 and 242 and nitride films 250 and 252, (260).

The substrate 210 supports the membrane 255 and the vibration energy conversion device 260. The substrate 210 may be made of any one of a nonconductor, a semiconductor, an organic layer, and an inorganic layer, but is not limited thereto.

The correction mass 220 is included in the through hole 230 and serves to amplify the amplitude of the external wave through the mass control of the membrane 255.

The shape of the correction mass 220 includes, but is not limited to, polygonal columns, cylinders, elliptical columns, polygonal pyramids, cones, cones, and the like. For example, the hexagonal-shaped correction mass 220 shown in FIG. 2A can be easily implemented by wet etching, and there is a process advantage. Etch etching is an etching method widely used because it has corrosion selectivity by wetting the chemical and etching the oxide film.

Further, the bottom surface width, height, and material of the correction mass 220 may be variously formed. This is formed in consideration of both the elastic coefficient of the membrane 255 and the piezoelectric element, the mass of the correction mass 220, and the like, as described above. The mass of the correction mass 220 may be greater than the mass of the membrane 255, but is not limited thereto. For example, the correction mass 220 may be formed of a metal that is heavier than the mass of the membrane 255. If the mass is excessively small, it is difficult to control the desired frequency.

However, for efficient and predictable resonance of the membrane oscillator 200, the correction mass 220 must maintain symmetry. Symmetry is important in terms of durability of the membrane vibration apparatus 200, and if the correction mass 220 is not symmetrical, the problem of the membrane 255 tearing easily occurs. Also, since symmetry has the effect of narrowing the spectrum of the common frequency, it is possible to efficiently absorb and amplify the energy of the desired frequency.

The through hole 230 is a space between the substrate 210 and the correction mass 220 where the bottom surface of the first oxide film 240 or the first nitride film 252 is exposed. Depending on the shape of the correction mass 220, the shape of the through hole 230 is also formed correspondingly.

A first oxide film 240 is deposited on one surface of the substrate 210 and a first nitride film 250 is deposited on the first oxide film 240. The first oxide film 240 and the first nitride film 250 constitute a membrane 255. On the membrane 255, a vibration energy converter 260 is formed.

A second oxide film 242 and a second nitride film 252 are deposited on the other surface of the substrate 210. The second oxide film 242 and the second nitride film 252 protect the membrane vibration device 200 when the other surface of the substrate 210 is in contact with another device or layer. The second oxide film 242 and the second nitride film 252 may be made of the same material as the first oxide film 240 and the first nitride film 242 but may be formed of different materials as required. Layers may be further included.

The vibration energy conversion device 260 includes a first electrode 262, a piezoelectric element 264, a second electrode 266, and a cover substrate 268. However, the vibration energy conversion device 260 may include other layers for energy conversion. Also, the vibration energy converter 260 may be formed by a MEMS process, but is not limited thereto.

The piezoelectric element 264 is an element that receives vibration energy and produces electric power corresponding to the vibration, and may be composed of any one of rochelle salt, barium titanate, and zinc oxide (ZnO) But is not limited thereto, as long as it is an element that enables energy conversion.

The first electrode 262 and the second electrode 266 are connected to a device such as a microphone to transmit the generated electrical energy.

The cover substrate 268 protects the vibration energy conversion device 260 from the outside and prevents contamination. The cover substrate 268 may not be formed on the membrane vibration device 200 when the second electrode serves to protect the vibration energy conversion device 260.

3A to 3I are cross-sectional views showing a stepwise manufacturing method of a membrane vibration device 300 according to another embodiment of the present invention.

First, a substrate 210 is prepared as shown in FIG. 3A. The substrate 210 may be a silicon substrate satisfying predetermined conditions, an n-type silicon substrate having a resistance of 5-10? Cm, but is not limited thereto. The material of the substrate 210 includes, but is not limited to, a non-metal such as a non-metal or a polymer, a semiconductor, an organic material, and an inorganic material. The cleaning of the substrate 210 can be performed by various methods. For example, the substrate 210 may be heated for a certain period of time, for example, 10 minutes or more, using a diluted solution of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ) It can be cleaned for about 30 minutes. Through this cleaning, contaminants are removed from the substrate 210.

3B, a first nitride layer 240 and a first nitride layer 250 are sequentially formed on a first surface 212 of the substrate 210. [ The structure including the first oxide film 240 and the first nitride film 250 is referred to as a membrane 255 and the membrane 255 serves to transmit vibration energy received from the outside to a piezoelectric element 264 do. At this time, the first oxide film 240 may be formed as a thermal oxide film formed by a thermal oxidation method, for example, from 0.2 탆 to 1 탆, particularly 0.2 탆, but is not limited thereto. The first nitride film 250 is formed of a film (Si _x N _y ) (X and Y are prime numbers) formed by an LSCVD (Low Stress Chemical Vapor Deposition) method and can be formed, for example, But is not limited thereto.

The second oxide film 242 and the second nitride film 252 are deposited on the second surface 214 of the substrate 210 while simultaneously forming the first oxide film 240 and the first nitride film 250 . The thicknesses of the first oxide layer 240 and the second oxide layer 242 are the same or substantially the same and the thicknesses of the first nitride layer 250 and the second nitride layer 252 are the same or substantially the same. It is not limited. The second oxide film 242 and the second nitride film 252 may be formed of different materials from the first oxide film 240 and the first nitride film 250 and may be formed by separate processes.

Referring to FIG. 3C, a first electrode 262 is formed on the membrane 255. The first electrode 262 is partly formed on a part of the membrane 255, but is not limited thereto. The first electrode 262 may be formed to have a predetermined thickness, for example, 0.2 탆 to 1 탆, particularly 0.4 탆, but is not limited thereto. The material of the first electrode 262 may be a metal such as aluminum, copper, or silver, or an inorganic oxide such as ITO or IZO, but is not limited thereto. For example, an aluminum film is formed on the first nitride film 250 using a thermal evaporator, and then the first electrode 262 is formed by patterning the aluminum film using photolithography and etching processes under predetermined conditions . The method of forming the first electrode 262 is not limited thereto.

Referring to FIG. 3D, a piezoelectric element 264 is formed on the first electrode 262. The piezoelectric element 264 serves to convert vibrational energy due to an external sound wave, a small-sized wave, or an external impact into electrical energy. The piezoelectric element 264 may be a zinc oxide (ZnO) film, rochelle salt, or barium titanate, but is not limited thereto. When a zinc oxide film is used as the piezoelectric element 264, the piezoelectric element 264 can be formed using an RF sputtering method. For example, using a high-purity zinc oxide film target, a target distance of 80 mm, an RF power of 400 W, an argon gas to oxygen gas ratio (Ar: O ₂ ) of 75:25 (flow rate 75:25 sccm) , And a pressure of 10 mtorr to form a zinc oxide film of 0.5 mu m on the lower electrode 262. However, the present invention is not limited thereto.

Referring to FIG. 3E, after the piezoelectric element 264 is formed, a second electrode 266 is formed on the piezoelectric element 264. The second electrode 266 may be formed of the same material layer as the first electrode 262, for example, an aluminum film, but is not limited thereto. When the second electrode 266 is formed of an aluminum film, it may be formed by the same process as the first electrode 262, but is not limited thereto.

Referring to FIG. 3F, a cover substrate 268 is formed to protect the detailed structures of the vibration energy conversion device 260.

3G, a photoresist 370 is deposited on the lower surface of the second nitride film 252. Next, as shown in FIG. The positions of the photoresists 370a and 370b are positions corresponding to the correction mass 220 to be formed at both end faces and the subsequent process. The positions of the photoresists 370a and 370b should be formed on the bottom surface of the second nitride film 252 in order to form the correction mass 220 on the bottom surface of the membrane 255. [ The photoresists 370a and 370b formed on both ends of the end face in a plan view are formed in the substrate region except for the through hole 230 shown in Fig. 2B.

3H, a part of the substrate 210, the second oxide film 242 and the second nitride film 252 are removed to form a through hole 230, and the substrate 210 in the through hole 230 is removed, A correction mass 220 is formed. When the dry or wet etching process is performed on the photoresists 370a and 370b shown in FIG. 3g, the regions of the substrate 210 on which the photoresists 370a and 370b are not formed are etched and removed. The area of the peripheral substrate 210 is removed around the photoresist 370b formed at the position corresponding to the correction mass 220 and finally the portion of the substrate 210 is removed at a position corresponding to the photoresist 370c The correction mass 220 is formed.

The membrane vibration apparatus 300 according to another embodiment of the present invention is not limited to the formation of the correction mass 220 by the above-described method, and the correction mass 220 can be formed by another process. Further, the material of the correction mass 220 may or may not be coincident with the substrate. The correction mass 220 may be made of a mass that is heavier than the membrane, for mass compensation.

Specifically, an oxide film and a nitride film are simultaneously formed on the first surface 212 and the second surface 214 of the substrate 210. A predetermined photoresist film (for example, AZ 9260) is applied under predetermined conditions, and the resultant is soft-baked. Soft Bake The result is sequentially exposed and developed according to the given conditions, then hard bake. As a result of hard baking, a photoresist pattern (not shown) is formed to define a portion to be exposed of the second nitride film 252. The exposed portion of the second nitride film 252 and the second oxide film 242 immediately below the second nitride film 252 are dry etched sequentially until the second surface 214 of the substrate 210 is exposed using the photoresist pattern as a mask. Thereafter, the photoresist pattern is removed. The second oxide film 242 and the second nitride film 252 remaining on the second surface 214 of the substrate 210 are etched after the second surface 214 of the substrate 210 is partially exposed, The exposed portions of the second surface 214 of the substrate 210 are etched until the first oxide film 240 formed on the first surface 212 of the substrate 210 is exposed, The exposed portion of the oxide film 240 is etched until the first nitride film 250 is exposed. At this time, in order to minimize lateral etching of the substrate 210, the exposed portion of the substrate 210 is preferably anisotropically etched. For example, the substrate 210 is put in a tetramethyl ammonium hydroxide (TMAH) solution under predetermined etching conditions The exposed portion of the second surface 214 may be etched. The exposed portion of the first oxide layer 240 may be etched using a BHF (buffered hydrofluoric acid) etchant. As a result of the etching, a through hole 230 through which the bottom surface of the first nitride film 250 is exposed is formed on the substrate 210 through the lower surface of the substrate 210, and a correction mass 220 corresponding to the photoresist of the reference numeral 370c ). At this time, etching can be performed so that only a part of the nitride film is exposed by changing the conditions. The exposed portion of the first nitride film 250 through the through hole 230 functions to transmit the vibration energy to the piezoelectric element 266. The through hole 230 may be formed to have a planar cross shape as shown in FIG. 2, but the present invention is not limited thereto.

Thereafter, as shown in FIG. 3I, the membrane vibration device 300 in which the photoresists 370a and 370b are removed is completed.

4 is a cross-sectional view of a membrane vibration device 400 according to another embodiment of the present invention.

Fig. 4 shows that the shape of the correction mass 220 can be changed as described above. The shape of the polygonal pyramid, the cone, the cone, the polygonal column, the cylinder and the ellipsoidal column is possible because the correction mass 420 adjusts the mass of the membrane 255 to cause resonance. However, symmetry can be maintained for predictable resonance and, as described above, in terms of durability of the membrane, but it may be asymmetrical.

5 is a cross-sectional view of a membrane vibration apparatus 500 according to another embodiment of the present invention.

5 is a view of a membrane vibration apparatus 500 formed by depositing both sides of a substrate 210 with an oxide film and a nitride film simultaneously according to another embodiment as described above. The second oxide film 540 and the second nitride film 550 can be formed depending on the material of the substrate because the surface opposite to the surface of the substrate on which the vibration energy conversion device is formed is in contact with other elements. However, the second oxide film 540 and the second nitride film 550 may be formed of different materials, and the order of the steps may be changed.

6A and 6B are cross-sectional views illustrating a process of a membrane vibration apparatus 600 according to another embodiment of the present invention.

A membrane 655 is formed on the substrate 610 and a vibration energy conversion device 660 is formed on the membrane 655. The manufacturing process of the membrane 655 and the vibration energy conversion device 660 is the same as the process shown in Figs. 3A to 3I except for the process shown in Fig. 3B, but is not limited thereto. 3B, in another embodiment of the membrane vibration apparatus 600, a membrane 655 is formed on only one side of the substrate 610. [ Thereafter, a photoresist is deposited on the other surface of the substrate 610, as shown in FIG. 6A. The correction mass 620 and the through hole 630 are formed by using the photomask. However, the membrane vibration device 600 according to still another embodiment of the present invention is not limited to the above-described process.

The membrane vibration apparatuses 200, 300, 400, 500, and 600 are one unit body, and the membrane vibration apparatuses 200, 300, 400, 500, And a microphone or the like. Therefore, the mass of the correction masses 220 and 620 can be adjusted to cause resonance, effectively converting the vibration energy into electric energy.

In the membrane vibration apparatuses 200, 300, 400, 500 and 600 according to the embodiments of the present invention, the correction masses 220 and 620 are formed on the bottom surface of the membrane 255, By correcting the mass, it is possible to cause external waves, waves and resonance.

Every object has its own frequency and has the property of absorbing the wave or wave corresponding to this natural frequency. The wave means that the medium vibrates in the direction perpendicular to the traveling direction of the wave, and has vibration energy. The resonance or resonance is the phenomenon in which the amplitude of the vibration system becomes largest when the frequency of the forced vibration power becomes equal to the natural frequency of the vibration system when the vibration system vibrates by applying external force. When the vibration transmitted to the device is similar to the natural frequency determined by the mass and the elastic modulus, resonance occurs. The resonance frequency in the free-

(where m is the mass and k is the modulus of elasticity). That is, it can be seen that the resonance frequency decreases as the mass increases, and increases as the elastic modulus increases. The amplitude of the oscillation is dependent on the damping, but can reach up to 100 times the initial oscillation. The present invention is characterized in that, by using the above-described resonance phenomenon, the vibration can be amplified and electric energy can be efficiently generated. Particularly, the membrane vibration apparatuses according to the embodiments of the present invention form the

correction masses

220 and 620 on the bottom surface of the

membranes

255 and 655, that is, on the surface receiving the vibration energy of the

membranes

255 and 655, Can be converted into electric energy.

The mass and the shape of the correction masses 220 and 620 can be configured differently according to the manufacturing process of forming the correction masses 220 and 620 and the frequency of the energy to be received from the outside and the oscillation frequency of the correction masses 220 and 620 . For example, the membrane vibrating apparatus 200, 300, 400, 500, 600 according to the embodiments of the present invention may be configured so that the masses of the correction masses 220, 620 correspond to the range from 20 Hz to 20 KHz, Can be determined.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them.

It is also to be understood that the terms such as " comprises, "" comprising," or "having ", as used herein, mean that a component can be implanted unless specifically stated to the contrary. But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

200: membrane vibrating device 210: substrate
212: first side of the substrate 214: second side of the substrate
220: Correction mass 230: Through hole
240: first oxide film 242: second oxide film
250: first nitride film 252: second nitride film
255: membrane 260: vibration energy converter
262: first electrode 264: piezoelectric element
266: second electrode 268: cover substrate
370a, 370b: photoresist 540: second oxide film
550: second nitride film 610: substrate
620: Correction mass 630: Through hole
655: Membrane 655: Membrane
660: Vibration energy conversion device

Claims

A substrate on which a through hole is formed;
A membrane formed on one surface of the substrate to cover the through hole;
A vibration energy conversion device formed on one surface of the membrane and including a piezoelectric element between two electrodes; And
A calibration mass formed in the through-hole on the other side of the membrane;
.

The method according to claim 1,
Wherein the correction mass is any one of a polygonal column, a cylinder, an elliptical column, a polygonal pyramid, a cone, and a cone.

The method according to claim 1,
Wherein the correction mass has a symmetrical shape.

The method according to claim 1,
Wherein the correction mass has a mass that is greater than a mass of the membrane.

The method according to claim 1,
Wherein the correction mass has a mass that matches the natural frequency of the membrane with the frequency of the external energy.

The method according to claim 1,
Wherein the substrate is any one of a nonconductor, a semiconductor, an organic material layer, and an inorganic material layer.

The method according to claim 1,
Wherein the piezoelectric element is any one of rochelle salt, barium titanate, and zinc oxide (ZnO).

The method according to claim 1,
Wherein the membrane comprises a first oxide film and a first nitride film on one surface of the substrate.

9. The method of claim 8,
A second oxide film and a second nitride film on the other surface of the substrate;
Further comprising:

Forming a substrate;
Forming a membrane on one surface of the substrate;
Forming a vibration energy conversion device on one side of the membrane, the piezoelectric energy conversion device comprising a piezoelectric element between two electrodes;
Depositing a photoresist on the other surface of the substrate so as to correspond to the following through holes and a calibration mass; And
Removing the substrate to form the through hole exposing a part of the bottom surface of the membrane; And
Forming the correction mass on the other surface of the membrane in the through hole;
&Lt; / RTI >

11. The method of claim 10, wherein forming the membrane comprises:
Wherein a first oxide film and a second oxide film are simultaneously deposited on the one surface and the other surface of the substrate and the first nitride film and the second nitride film are simultaneously deposited on the first oxide film and the second oxide film, A method of manufacturing a vibrating device.

11. The method of claim 10, wherein depositing the photoresist comprises:
Wherein the second oxide film and the second nitride film are sequentially deposited on the other surface of the substrate, and then the photoresist is formed.

11. The method of claim 10,
Wherein the step of forming the through holes and the step of forming the correction mass are simultaneously performed by etching.