WO2016129597A1 - エレクトレット素子、電気機械変換器およびエレクトレット素子の製造方法 - Google Patents
エレクトレット素子、電気機械変換器およびエレクトレット素子の製造方法 Download PDFInfo
- Publication number
- WO2016129597A1 WO2016129597A1 PCT/JP2016/053836 JP2016053836W WO2016129597A1 WO 2016129597 A1 WO2016129597 A1 WO 2016129597A1 JP 2016053836 W JP2016053836 W JP 2016053836W WO 2016129597 A1 WO2016129597 A1 WO 2016129597A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- layer
- sio
- electret
- comb electrode
- electrode
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G7/00—Capacitors in which the capacitance is varied by non-mechanical means; Processes of their manufacture
- H01G7/02—Electrets, i.e. having a permanently-polarised dielectric
- H01G7/025—Electrets, i.e. having a permanently-polarised dielectric having an inorganic dielectric
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N1/00—Electrostatic generators or motors using a solid moving electrostatic charge carrier
- H02N1/06—Influence generators
- H02N1/10—Influence generators with non-conductive charge carrier
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N1/00—Electrostatic generators or motors using a solid moving electrostatic charge carrier
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N1/00—Electrostatic generators or motors using a solid moving electrostatic charge carrier
- H02N1/002—Electrostatic motors
- H02N1/006—Electrostatic motors of the gap-closing type
- H02N1/008—Laterally driven motors, e.g. of the comb-drive type
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49226—Electret making
Definitions
- the present invention relates to an electret element, an electromechanical transducer, and a method for manufacturing the electret element.
- either method is a method of driving charge from the surface, it is difficult to control the fixed position (depth from the surface) of the charge, and it is impossible to uniformly charge the deep part of the insulator. Since the charge fixed near the surface reacts with water vapor in the air and is neutralized, there is a disadvantage that the life of the electret is shortened.
- alkali metal ions are used in the method described in Patent Document 3, but generally alkali metals are excluded from the manufacturing apparatus because they deteriorate the electrical characteristics of the semiconductor element. Therefore, in this method, it is difficult to make an electret in a part of the CMOS device, and the application range is limited. Further, in this method, since alkali metal ions are fixed near the SiO 2 surface, it is necessary to additionally perform a treatment such as a water repellent film in order to prevent the life of the electret from being shortened.
- an electret element includes an Si layer, an SiO 2 layer formed on the surface of the Si layer, and an electret formed in the vicinity of the interface between the Si layer in the SiO 2 layer.
- the electromechanical transducer includes the first and second electrodes that are arranged to face each other and at least one of which is movable, and the first electrode is configured by the electret element of the first aspect. The at least one of the first and second electrodes moves to convert between electrical energy and mechanical energy.
- the Si layer is formed of a Si substrate, and at least a part of the circuit elements for driving the electromechanical transducer is formed on the Si substrate. Preferably it is formed.
- the electromechanical converter of the second or third aspect it is preferable that at least one of the first and second electrodes is moved by the action of an external force to generate power.
- the stationary part provided with the first electrode, the movable part provided with the second electrode, the first electrode It is preferable to include a voltage source that applies a voltage between the two electrodes, and a control unit that drives the movable part by controlling the voltage applied by the voltage source.
- a manufacturing method of an electret element the Si layer SiO 2 layer formed, while maintaining the first temperature of the SiO 2 layer becomes a semiconductor state, Si layer and SiO 2 a voltage is applied between the layers, in a state where a voltage is applied, the Si layer SiO 2 layer formed, the SiO 2 layer is varied to a second temperature to recover the insulation from the first temperature.
- an electret device including an electret with excellent life performance.
- FIG. 1 is a diagram for explaining an electret device according to the first embodiment.
- FIG. 2 is a diagram showing the electrical characteristics of the Si / SiO 2 interface.
- FIG. 3 is a diagram for explaining the charging principle in the electret element according to the present embodiment.
- FIG. 4 is a diagram for explaining the charging principle in the electret element according to the present embodiment, and shows a state where the applied voltage is zero.
- FIG. 5 is a diagram for explaining the charging process in detail.
- FIG. 6 is a diagram for explaining the charging process in detail.
- FIG. 7 is a diagram for explaining the charging process in detail.
- FIG. 8 is a schematic diagram showing a schematic configuration of the vibration power generation device.
- FIG. 9 is a diagram showing a cross-sectional shape along B1-B1 in FIG. FIG.
- FIG. 10 is a diagram showing a B1-B1 cross-sectional shape after an oxide film is formed and charged.
- FIG. 11 is a diagram illustrating the application form of the bias voltage V1.
- FIG. 12 is a schematic diagram showing in detail the electric double layer formed on the comb electrode.
- FIG. 13 is a schematic diagram showing in detail the structure of the region surrounded by the broken line C in FIG.
- FIG. 14 is a diagram illustrating a state where the applied voltage is V1.
- FIG. 15 is a diagram illustrating a state in which the applied voltage is zero.
- FIG. 16 is a diagram illustrating the power generation operation of the vibration power generation device.
- FIG. 17 is a diagram illustrating a schematic configuration of the MEMS shutter.
- FIG. 11 is a diagram illustrating the application form of the bias voltage V1.
- FIG. 12 is a schematic diagram showing in detail the electric double layer formed on the comb electrode.
- FIG. 13 is a schematic diagram showing in detail the structure of the region surrounded by the broken
- FIG. 19 is a diagram for explaining the driving operation of the comb-shaped actuator, and shows a case where the applied voltage V is set to 0 ⁇ V ⁇ V1.
- FIG. 21 is a diagram for explaining the effect of the electret.
- an Si layer and an SiO 2 layer are formed across an interface, and an electret is formed near the interface on the SiO 2 layer side.
- the inventor found the electrical characteristics of the Si / SiO 2 interface as described below, and formed electrets in the SiO 2 layer by utilizing the electrical characteristics.
- a sample 100 is obtained by forming a SiO 2 layer 102 on one surface of a Si layer 101.
- Au layers 103 and 104 are formed as electrodes on the Si layer 101 and the SiO 2 layer 102.
- Si is heated to a high temperature (about 500 to 700 ° C.)
- the electrical resistivity decreases due to an increase in intrinsic carrier concentration, and can be regarded as a conductor.
- SiO 2 is an excellent insulator at room temperature, but at high temperatures (about 500 to 700 ° C.), the electrical resistivity can be reduced to the order of 10 4 ⁇ m (similar to a semiconductor) due to the influence of thermally excited electrons.
- a high temperature about 500 to 700 ° C.
- FIG. 1 shows the electrical characteristics of the Si / SiO 2 interface at a high temperature (about 610 ° C.).
- FIG. 2 shows the relationship between the applied voltage V1 and the current i, and it has been found that the Si / SiO 2 interface at a high temperature has a rectifying effect like a Schottky junction.
- FIG. 3 is a diagram for explaining the charging principle in the electret element according to the present embodiment.
- a substrate for example, SOI (Silicon On Insulator) substrate
- SOI Silicon On Insulator
- FIG. 5 When the voltage V1 is applied as shown in FIG. 5, an electric double layer is formed with the Si / SiO 2 interface 204 interposed therebetween.
- a silicon layer doped with impurities is used, but in that case, both p-type and n-type can be used. Further, it may be a Si layer containing no impurities.
- the Si / SiO 2 interface has a rectifying effect as shown in FIG. 2 in a high temperature state. Therefore, positive charges are accumulated on the Si layer 202 side across the upper Si / SiO 2 interface 204, and negative charges are accumulated on the SiO 2 layer 201 side. On the other hand, the electric double layer is not formed because the voltage is applied in the direction in which the current flows at the lower Si / SiO 2 interface.
- the negative charges in the SiO 2 layer 201 since the SiO 2 layer 201 is insulative and remains trapped in the vicinity of the Si / SiO 2 interface 204 after the applied voltage V1 is canceled.
- an electric field E is formed in the SiO 2 layer 201 as shown in FIG.
- This electric field E is an electric field by an electret, and the potential difference between the Si / SiO 2 interface 204 and the Si / SiO 2 interface 205 is V1. That is, an electret having a voltage V1 is formed.
- FIG. 5 is a schematic diagram of a structure in which an SiO 2 layer is sandwiched between Si layers.
- the surface charges Q2 and Q3 are charges constituting the electric double layer shown in FIG. Although the distance d between the surface charges Q2 and Q3 in the electric double layer is very small, in FIG. 5, the distance d is exaggerated and displayed large for easy understanding, and the surface charge Q2 in the SiO 2 layer 201 is illustrated. It shall be fixed in position. In FIG. 5, it is assumed that the surface charge Q1 is also charged in the Si layer 203 and is neutral throughout the structure. For this reason, it is assumed that only the electric fields E1 and E2 in the SiO 2 layer 201 have non-zero magnitude, and the potential difference between the Si layers 202 and 203 due to the electric fields E1 and E2 is V.
- current flows through the Si / SiO 2 interface 205, so that the following equations (7) and (8) are established in the state of FIG.
- Expressions (7) and (8) are applied to Expression (5)
- Expression (9) is obtained.
- This Q2 is a fixed surface charge charged on the SiO 2 layer 201 and forms an electret.
- the applied voltage V1 is V1> 0, Q2 ⁇ 0.
- FIG. 6 the change in potential in the stacking direction is shown on the right side of the substrate 200 in the figure. In the case of FIG.
- the surface charge Q1 is represented by the equation (10) by substituting the equation (9) into the equation (5).
- Q1 ⁇ 1 ⁇ S ⁇ (V1 ⁇ V) / (g + d) (10)
- Equation (10) represents the amount of positive charge movement when the potential difference changes from V1 to V.
- Equation (10) represents the amount of positive charge movement when the potential difference changes from V1 to V.
- Q1 ⁇ 1 ⁇ S ⁇ V1 / (g + d) (11)
- the surface charge Q3 is the sum of the charge ⁇ Q2 induced by the surface charge Q2 and the charge ⁇ Q1 due to the outflow of the minute charge Q1. Therefore, there is basically an electric double layer ⁇ Q2, -Q2 ⁇ with a high charge density, and it is an image that a small amount of charge Q1 moves between the upper and lower Si layers according to the potential difference.
- the electric field E1 stays inside the SiO 2 layer 201 and has a small utility value.
- an electric field can be generated in the gap space by applying a charging process to a predetermined structure as described later.
- Electricity / mechanical conversion conversion between electric energy and mechanical energy
- the electret element of the first embodiment is applied to a comb-tooth vibration power generation device that is an example of a mechanical-electric converter.
- FIG. 8 is a schematic diagram showing a schematic configuration of the vibration power generation device 300.
- this vibration power generation device 300 is also a semiconductor integrated circuit manufacturing technique similar to the case of a general MEMS (for example, deep etching by ICP-RIE). It is formed by processing using.
- the vibration power generation device 300 includes a fixed comb electrode 302 and a movable comb electrode 303 on a rectangular ring-shaped base 301.
- the movable comb electrode 303 is elastically supported on the pedestal 301 by the elastic support portion 305.
- Each comb tooth of the movable comb electrode 303 is arranged between each comb tooth of the fixed comb electrode 302 via a gap.
- the movable comb electrode 303 is provided with a weight 304.
- the load 320 is connected between the fixed comb electrode 302 and the movable comb electrode 303.
- electrets are formed on the fixed comb electrode 302, and power is generated when the external force is applied to the vibration power generation device 300 and the movable comb electrode 303 vibrates.
- the oxide film (SiO 2 layer) formed on the surface of the Si layer is formed by the thermal oxidation method.
- the present invention is not limited to this, and the oxide film (SiO 2 layer) is formed by various oxide film formation methods. It may be formed.
- the oxide film (SiO 2 layer) may be formed by depositing SiO 2 on the Si layer by CVD.
- FIG. 9 is a diagram showing a cross-sectional shape along B1-B1 of FIG. 8, showing a shape before the oxide film is formed.
- the pedestal 301 is formed by a handle layer (Si) of the SOI substrate.
- the fixed comb electrode 302 is formed by a device layer (Si) of an SOI substrate.
- a portion indicated by reference numeral 307 is a buried oxide film (SiO 2 ) called a BOX layer of the SOI substrate.
- the movable comb electrode 303, the elastic support portion 305, and the weight 304 are formed by a device layer of an SOI substrate.
- FIG. 10 is a diagram showing a B1-B1 cross-sectional shape after an oxide film is formed and charged.
- An oxide film 310 is formed on the surfaces of the fixed comb electrode 302 and the pedestal 301 formed of the Si layer.
- the oxide film 310 is heated to a temperature at which the oxide film 310 as the SiO 2 layer becomes a semiconductor using a heater or the like. Then, if the oxide film 310 is made into a semiconductor, it is cooled to a temperature at which the semiconductor-made oxide film 310 recovers its insulating property while a bias voltage V1 (10 to 200 V) is applied. As shown in FIG.
- a bias voltage V1 is applied between the fixed comb electrode 302, the movable comb electrode 303, and the pedestal 301 as shown in FIG.
- the vibration power generation device 300 is heated to a temperature (500 to 700 ° C.) at which the oxide film 310 made of SiO 2 becomes a semiconductor.
- a bias voltage V1 is applied so that an electric double layer is formed across the Si / SiO 2 interface 306 of the fixed comb electrode 302 (see FIG. 10).
- FIG. 12 schematically shows a cross section (a cross section parallel to the paper surface of FIG. 11) where the fixed comb electrode 302 and the movable comb electrode 303 overlap in a state where the electric double layer is formed.
- the oxide film formed on the fixed comb electrode 302 is denoted by reference numeral 310a
- the oxide film formed on the movable comb electrode 303 is denoted by reference numeral 310b.
- the Si layer of the fixed comb electrode 302 is denoted by reference numeral 311a
- the Si layer of the movable comb electrode 303 is denoted by reference numeral 311b.
- the SiO 2 layer (the oxide film 310a and the BOX layer 307) is made into a semiconductor and its electric resistivity is lowered, the inside of the SiO 2 layer has almost the same potential. For this reason, the entire Si / SiO 2 interface 306 has a uniform charge density, and an electric double layer is formed up to the tips of the comb teeth. If the electric double layer is formed on the entire Si / SiO 2 interface 306, it is electrostatically shielded by the SiO 2 layer having a reduced resistivity, so that no electric field is generated outside the electric double layer. As a result, the electrostatic force between the comb-tooth electrodes becomes zero, and by observing this, it can be used as a standard for completion of the charging process.
- FIG. 13 is a schematic diagram showing in detail the structure of the region surrounded by the broken line C in FIG. 12, and corresponds to FIG. 5 of the first embodiment.
- Surface charges Q5 and Q6 constituting an electric double layer across the Si / SiO 2 interface 306 are formed on the oxide film 310a and the Si layer 311a of the fixed comb electrode 302.
- the surface charge Q ⁇ b> 4 indicates the charge charged on the Si layer 311 b of the movable comb electrode 303.
- E3 is an electric field formed in the oxide film 310b of the movable comb electrode 303.
- E5 and E6 are electric fields formed in the oxide film 310a of the fixed comb electrode 302.
- E4 is an electric field formed in the gap space G between the comb electrodes 302 and 303.
- the region including the surface charge Q4 the region including the interface between the oxide film 310b and the gap space G, the region including the interface between the oxide film 310a and the gap space G, the region including the surface charge Q5, and the surface charge Q6.
- Gauss's law is applied to each of the regions including the following equations (13) to (17) are obtained.
- S is a cross-sectional area when the region C in FIG. 12 is cut out.
- ⁇ 0 and ⁇ 1 are the dielectric constants of the gap space G and the oxide film (SiO 2 ).
- FIG. 16 shows a state in which the movable comb electrode 303 slides with respect to the fixed comb electrode 302 and the overlap between the comb teeth becomes zero (c), and a state in which half of the comb teeth overlap ( It schematically shows b) and a state (a) in which the entire comb teeth overlap. This corresponds to the case where the load 320 having the low impedance limit is connected, and corresponds to the change in the amount of the surface charge Q4 due to the change in the area S (corresponding to the overlap area) in the equation (22). ing.
- one minus sign shown in the surface charge Q5 is regarded as a charge amount ⁇ q
- one plus sign shown in the surface charges Q4 and Q6 is regarded as a charge amount + q, so that the change in the charge amount is considered.
- the movable comb electrode 303 moves in the left direction in the figure with respect to the fixed comb electrode 302 and the overlap area of the comb teeth is reduced to half.
- the amount of surface charge Q4 decreases from + 2q to + q
- the amount of surface charge Q6 increases from + 6q to + 7q.
- a current I flows from the Si layer 311b of the movable comb electrode 303 to the Si layer 311a of the fixed comb electrode 302.
- the states (a) to (c) shown in FIG. 16 are (a) ⁇ (b) ⁇ (c) ⁇ (b ) ⁇ (a) ⁇ (b) ⁇ ...
- alternating current flows to the load 320.
- the overlap area changes without changing the charge amount of the surface charge Q4, so that the potential difference V changes.
- the electric power to be extracted can be maximized by adjusting the load impedance.
- FIG. 17 is a diagram showing a schematic configuration of the MEMS shutter 400 of the present embodiment.
- symbol was attached
- the fixed comb electrode 302 and the movable comb electrode 303 constitute a comb-type actuator.
- the movable comb electrode 303 is provided with a shutter portion 404 having an opening 404a.
- a voltage for driving the actuator is applied between the fixed comb electrode 302 and the movable comb electrode 303 by the voltage source 401.
- the control unit 402 controls the applied voltage V of the voltage source 401 to move the movable comb electrode 303 provided with the shutter unit 404 in the direction of arrow R.
- the shutter unit 404 is disposed on the optical path. When the opening 404a of the shutter unit 404 is disposed in the optical path by the movement of the movable comb electrode 303, the light beam passes through the shutter unit 404. On the other hand, the non-opening region (shielding region) of the shutter unit 404 is arranged in the optical path, so that the light beam is blocked by the shutter unit 404.
- 18A shows the forces F1 and F2 acting on the movable comb electrode 303
- FIG. 18B shows the relationship between the applied voltage V and the electric field E4.
- an electric field E4 represented by the above-described formula (24) is formed in the gap space G between the fixed comb electrode 302 and the movable comb electrode 303.
- an electric field E4 represented by the above-described formula (24) is formed.
- a rightward force F1 shown in the drawing acting on the movable comb electrode 303 is drawn between the comb teeth of the fixed comb electrode 302.
- FIG. 19 shows the case where the applied voltage V is set to 0 ⁇ V ⁇ V1.
- the electric field E4 in the gap space G is expressed by the following equation (25) obtained by applying the equations (13) and (14) to the equation (22) described above.
- the electrostatic force F1 attracted by the movable comb electrode 303 in the direction of the fixed comb electrode 302 is reduced, and the movable comb electrode 303 is elastically supported by the electrostatic force F1 as shown in FIG. It moves to the left in the figure to a position that balances with the elastic force F2 of the part 305.
- E4 ⁇ (V1 ⁇ V) / [g ′ + d ⁇ ( ⁇ 0 / ⁇ 1)] (25)
- V V1
- the charge amounts of the surface charge Q5 and the surface charge Q6 are equal, and the potential difference in the electric double layer is equal to V1.
- the electric field E4 in the gap space G becomes zero
- the electrostatic force F1 between the fixed comb electrode 302 and the movable comb electrode 303 becomes zero. Therefore, the deformation of the elastic support portion 305 is zero as shown in FIG.
- the electrostatic force acting between the comb teeth in the comb-tooth actuator is proportional to the square of the electric field. Therefore, in the case where the comb actuator is driven only by the applied voltage V without using an electret, the relationship between the applied voltage V and the electrostatic force F1 is a quadratic curve as shown by the line L1 in FIG. . On the other hand, in the case of a comb-shaped actuator having an electret as in the present embodiment, the relationship between the applied voltage V and the electrostatic force F1 is as shown by a line L2.
- the line L2 is a line that is moved in the positive direction of the horizontal axis by an amount corresponding to the electret charging voltage V1.
- the electrostatic force ⁇ Fb with the electret is larger than the electrostatic force ⁇ Fa without the electret. That is, when the electret is formed, a large electrostatic force can be obtained as compared with the configuration of only the external bias voltage.
- the electret element includes the interface between the Si layer 202, the SiO 2 layer 201 formed on the surface of the Si layer 202, and the Si layer 202 in the SiO 2 layer 201 as shown in FIGS.
- An electret (surface charge Q2) formed in the vicinity. Since the surface charge Q2 constituting the electret is fixed in the vicinity of the Si / SiO 2 interface, the SiO 2 layer 201 functions as a protective film, and the lifetime of the electret can be improved.
- the Si layer 202 SiO 2 layer 201 is formed while maintaining the first temperature of the SiO 2 layer 201 is a semiconductor state (about 500 ⁇ 700 ° C.), and the Si layer 202 and the SiO 2 layer 201 A voltage is applied between the first temperature and the Si layer 202 on which the SiO 2 layer 201 is formed in a state where the voltage is applied.
- the second temperature at which the SiO 2 layer 201 recovers the insulating property from the first temperature It is formed by changing to (for example, a temperature of about 300 ° C. or less).
- the electret is formed by the method of moving and fixing the charge in the SiO 2 layer, it is arranged in a narrow gap portion or a sealed space like the comb side surface of the comb electrode as shown in FIG. Even with the formed electrode, the electret can be easily formed. Since electret formation in a narrow gap portion is facilitated, the gap dimension can be designed to be smaller, and the performance as a power generation device or actuator is improved.
- the electric charge moves without being directly related to the electric field on the device surface, the electric charge can be charged with a uniform charge density without special measures during the charging process (electret forming process). Further, as shown in FIG. 3, since the electric double layer is formed for charging, the gap between charges charged across the interface is very small, and a large charge density can be obtained even at a small potential.
- the fixed comb electrode 302 and the movable comb electrode 303 are provided so as to face each other, and the fixed comb electrode 302 is configured by an electret element.
- an electromechanical conversion that converts between electrical energy and mechanical energy by moving the movable comb electrode 303, that is, by displacing the movable comb electrode 303 with respect to the fixed comb electrode 302. Function as a vibration generator (for example, vibration power generation device 300).
- the electret is formed on the stationary comb electrode 302 side, but the electret may be formed on the movable comb electrode 303 side. Furthermore, not only the structure which makes one of a pair of comb-tooth electrode movable, but it is good also as a structure which both a pair of comb-tooth electrode moves.
- Electromechanical converters include, in addition to the power generation device, an actuator for driving the shutter unit 404 as shown in FIG.
- an actuator for driving the shutter unit 404 as shown in FIG.
- the control unit 402 in FIG. It is possible to form a part of the circuit elements in the Si layer (device layer) of the base 301. Examples of such circuit elements include transistors for drive circuits, FETs and resistors for amplifier circuits of microphones and sensors, and rectifier diodes for power generation elements.
- the electrodes 302 and 303 are comb-shaped electrodes, but a parallel plate structure in which the gap distance changes may be used. Thereby, an electret element can be utilized with respect to a parallel plate type vibration electric power generation device and a capacitor
- the entire device including the fixed comb electrode 302 and the movable comb electrode 303 is heated and charged, but the region related to the formation of the electret (SiO 2 layer to be charged) And only the Si layer in which a current is desired to flow) may be locally heated with a laser or the like. This makes it possible to apply to a device such as an electret microphone with a built-in amplifier circuit.
Abstract
Description
本発明の第2の態様によると、電気機械変換器は、互いに対向配置され、少なくとも一方が移動可能な第1および第2電極を備え、第1電極は第1の態様のエレクトレット素子で構成され、第1および第2電極の少なくとも一方が移動することにより、電気的エネルギーと機械的エネルギーとの間の変換を行う。
本発明の第3の態様によると、第2の態様の電気機械変換器において、Si層はSi基板で構成され、電気機械変換器を駆動するための回路素子の少なくとも一部が、Si基板に形成されていることが好ましい。
本発明の第4の態様によると、第2または3の態様の電気機械変換器において、外力の作用により第1および第2電極の少なくとも一方の電極が移動して発電を行うことが好ましい。
本発明の第5の態様によると、第2または3の態様の電気機械変換器において、第1電極が設けられた静止部と、第2電極が設けられた可動部と、第1電極と第2電極との間に電圧を印加する電圧源と、電圧源による印加電圧を制御して可動部を駆動する制御部と、を備えることが好ましい。
本発明の第6の態様によると、エレクトレット素子の製造方法は、SiO2層が形成されたSi層を、SiO2層が半導体状態となる第1の温度に維持しつつ、Si層とSiO2層との間に電圧を印加し、電圧を印加した状態で、SiO2層が形成されたSi層を、第1の温度からSiO2層が絶縁性を回復する第2の温度まで変化させる。
-第1の実施の形態-
第1の実施形態に係るエレクトレット素子は、界面を挟んでSi層とSiO2層とを形成し、SiO2層側の界面近傍にエレクトレットを形成したものである。本発明者は、以下に説明するようなSi/SiO2界面の電気的特性を見出し、その電気的特性を利用してSiO2層にエレクトレットを形成した。
図3は、本実施の形態のエレクトレット素子における帯電原理を説明する図である。SiO2層201をSi層202,203で挟んだ構造の基板(例えば、SOI(Silicon On Insulator)基板)200をSiO2が半導体化する高温(500~700℃)に加熱した状態で、図3に示すように電圧V1を印加すると、Si/SiO2界面204を挟んで電気二重層が形成される。なお、通常、Si層には不純物がドープされたものが使用されるが、その場合、p型およびn型のどちらも使用することができる。また、不純物を含まないSi層であっても良い。
ε1・E1・S=Q1 …(1)
(ε1・E2-ε1・E1)・S=Q2 …(2)
-ε1・E2・S=Q3 …(3)
g・E1+d・E2=-V …(4)
Q1=-d・Q2/(g+d)-ε1・S・V/(g+d) …(5)
Q3=-Q2-Q1 …(6)
V=V1 …(7)
Q1=0 …(8)
Q2=-ε1・S・V1/d …(9)
Q1=-ε1・S・(V1-V)/(g+d) …(10)
Q1=-ε1・S・V1/(g+d) …(11)
|Q1|<<|Q2| …(12)
第2の実施の形態は、第1の実施の形態のエレクトレット素子を、機械電気変換器の一例である櫛歯構造の振動発電デバイスに適用したものである。図8は振動発電デバイス300の概略構成を示す模式図である。この振動発電デバイス300も第1の実施の形態のエレクトレット素子の場合と同様に、SOI基板を一般的なMEMSの場合と同様の半導体集積回路作製技術(例えば、ICP-RIEによる深掘りエッチング等)を用いて加工することにより形成される。
帯電処理を行う場合、図11に示すようにバイアス電圧V1を、固定櫛歯電極302と可動櫛歯電極303および台座301との間に印加する。まず、振動発電デバイス300を、SiO2から成る酸化膜310が半導体化する温度(500~700℃)まで加熱する。そして、固定櫛歯電極302のSi/SiO2界面306を挟んで電気二重層が形成されるように(図10参照)、バイアス電圧V1を印加する。
ε1・E3・S=Q4 …(13)
(ε0・E4-ε1・E3)・S=0 …(14)
(ε1・E5-ε0・E4)・S=0 …(15)
(ε1・E6-ε1・E5)・S=Q5 …(16)
-ε1・E6・S=Q6 …(17)
g1・E3+g2・E4+g3・E5+d・E6=-V …(18)
Q6=-Q5-Q4 …(19)
Q5=-[(d+g1+g2(ε1/ε0)+g3)/d]Q4
-ε1・S・V/d …(20)
Q5=-ε1・S・V1/d …(21)
Q4=-ε0・S・(V1-V)/[g’+d・(ε0/ε1)] …(22)
ただし、g’=g2+(g1+g3)・(ε0/ε1)
Q4=-ε0・S・V1/[g’+d・(ε0/ε1)] …(23)
E4=-V1/[g’+d・(ε0/ε1)] …(24)
次に、振動発電デバイス300の発電動作について説明する。図16は、固定櫛歯電極302に対して可動櫛歯電極303がスライド移動して、櫛歯同士のオーバーラップがゼロとなった状態(c)と、櫛歯の半分がオーバーラップした状態(b)と櫛歯の全体がオーバーラップした状態(a)とを模式的に示したものである。これは、低インピーダンス極限の負荷320を接続した場合に相当し、式(22)において、面積S(オーバーラップ面積に相当)が変化することによって面電荷Q4の電荷量が変化することに対応している。なお、ここでは説明を簡単にするために、面電荷Q5に示すマイナス符号1つを電荷量-qとし、面電荷Q4,Q6に示すプラス符号1つを電荷量+qとみなして電荷量の変化を説明する。
第3の実施の形態は、MEMSシャッタの櫛歯型アクチュエータに、第1の実施の形態のエレクトレット素子を適用したものである。図17は本実施の形態のMEMSシャッタ400の概略構成を示す図である。なお、図8に示した振動発電デバイス300と同様の構成要素には同一の符号を付した。すなわち、MEMSシャッタ400はSOI基板を加工することにより形成され、矩形リング形状の台座301に固定された固定櫛歯電極302、弾性支持部305によって台座301に固定された可動櫛歯電極303を備えている。固定櫛歯電極302および可動櫛歯電極303は、櫛歯型アクチュエータを構成している。可動櫛歯電極303には開口404aが形成されたシャッタ部404が設けられている。
図18~20は櫛歯型アクチュエータの駆動動作を説明する図である。図18は電圧源401の印加電圧VがV=0の場合を示す。図18において、(a)は可動櫛歯電極303に作用する力F1,F2を示し、(b)は印加電圧Vと電場E4との関係を示す図である。印加電圧V=0の場合、Si層311aとSi層311bとは同電位となり、図15,16に示す場合と同じ状態となっている。固定櫛歯電極302と可動櫛歯電極303との間のギャップ空間Gには、前述した式(24)で表される電場E4が形成される。この電場E4によって、可動櫛歯電極303には、固定櫛歯電極302の櫛歯間に引き込まれるような図示右向きの力F1が作用する。
E4=-(V1-V)/[g’+d・(ε0/ε1)] …(25)
日本国特許出願2015年第26839号(2015年2月13日出願)
Claims (6)
- Si層と、
前記Si層の表面に形成されたSiO2層と、
前記SiO2層における前記Si層との界面の近傍に形成されたエレクトレットと、を備えるエレクトレット素子。 - 互いに対向配置され、少なくとも一方が移動可能な第1および第2電極を備え、
前記第1電極は請求項1に記載のエレクトレット素子で構成され、
前記第1および第2電極の少なくとも一方が移動することにより、電気的エネルギーと機械的エネルギーとの間の変換を行う電気機械変換器。 - 請求項2に記載の電気機械変換器において、
前記Si層はSi基板で構成され、
前記電気機械変換器を駆動するための回路素子の少なくとも一部が、前記Si基板に形成されている電気機械変換器。 - 請求項2または3に記載の電気機械変換器において、
外力の作用により前記第1および第2電極の少なくとも一方の電極が移動して発電を行う電気機械変換器。 - 請求項2または3に記載の電気機械変換器において、
前記第1電極が設けられた静止部と、
前記第2電極が設けられた可動部と、
前記第1電極と前記第2電極との間に電圧を印加する電圧源と、
前記電圧源による印加電圧を制御して前記可動部を駆動する制御部と、を備える電気機械変換器。 - エレクトレット素子を製造する方法であって、
SiO2層が形成されたSi層を、前記SiO2層が半導体状態となる第1の温度に維持しつつ、前記Si層と前記SiO2層との間に電圧を印加し、
前記電圧を印加した状態で、前記SiO2層が形成された前記Si層を、前記第1の温度から前記SiO2層が絶縁性を回復する第2の温度まで変化させるエレクトレット素子の製造方法。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/550,215 US10833607B2 (en) | 2015-02-13 | 2016-02-09 | Electret element, electromechanical converter and method for manufacturing electret element |
KR1020177018341A KR101938506B1 (ko) | 2015-02-13 | 2016-02-09 | 일렉트릿 소자, 전기기계 변환기 및 일렉트릿 소자의 제조방법 |
EP16749241.2A EP3244527B1 (en) | 2015-02-13 | 2016-02-09 | Electret element, electromechanical converter and method for producing electret element |
CN201680009509.XA CN107251402B (zh) | 2015-02-13 | 2016-02-09 | 驻极体元件、机电转换器以及驻极体元件的制造方法 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2015-026839 | 2015-02-13 | ||
JP2015026839A JP6569933B2 (ja) | 2015-02-13 | 2015-02-13 | エレクトレット素子、電気機械変換器およびエレクトレット素子の製造方法 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2016129597A1 true WO2016129597A1 (ja) | 2016-08-18 |
Family
ID=56614704
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2016/053836 WO2016129597A1 (ja) | 2015-02-13 | 2016-02-09 | エレクトレット素子、電気機械変換器およびエレクトレット素子の製造方法 |
Country Status (6)
Country | Link |
---|---|
US (1) | US10833607B2 (ja) |
EP (1) | EP3244527B1 (ja) |
JP (1) | JP6569933B2 (ja) |
KR (1) | KR101938506B1 (ja) |
CN (1) | CN107251402B (ja) |
WO (1) | WO2016129597A1 (ja) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2018088778A (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人 東京大学 | 振動発電デバイス |
WO2018101046A1 (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人東京大学 | 振動発電デバイス |
WO2018101017A1 (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人 東京大学 | 振動発電素子 |
JP2021069280A (ja) * | 2021-02-04 | 2021-04-30 | 国立大学法人 東京大学 | 振動発電素子 |
JP2022082718A (ja) * | 2021-02-04 | 2022-06-02 | 国立大学法人 東京大学 | 振動発電素子 |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110417955A (zh) * | 2018-04-28 | 2019-11-05 | Oppo广东移动通信有限公司 | 电子设备 |
JP6792249B2 (ja) * | 2018-05-08 | 2020-11-25 | 国立大学法人 東京大学 | 振動発電装置 |
JP6985702B2 (ja) | 2018-05-31 | 2021-12-22 | 国立大学法人 東京大学 | 振動発電装置および振動発電素子 |
JP7249597B2 (ja) * | 2020-03-27 | 2023-03-31 | 国立大学法人 東京大学 | 発電素子の製造方法、及び、発電素子 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004114261A (ja) * | 2002-09-27 | 2004-04-15 | Ntt Electornics Corp | マイクロアクチュエータ装置及びこれを用いた光スイッチシステム |
JP2013013256A (ja) * | 2011-06-29 | 2013-01-17 | Aoi Electronics Co Ltd | エレクトレット膜およびこれを用いた振動発電素子 |
JP5627130B2 (ja) * | 2012-08-30 | 2014-11-19 | アオイ電子株式会社 | 正イオンを含有したエレクトレットの形成方法 |
WO2015019919A1 (ja) * | 2013-08-08 | 2015-02-12 | アオイ電子株式会社 | アクチュエータ、シャッタ装置、流体制御装置、スイッチおよび2次元走査型センサ装置 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH09283373A (ja) | 1996-04-15 | 1997-10-31 | Matsushita Electric Works Ltd | シリコン酸化膜エレクトレット |
EP1662308A4 (en) | 2003-08-21 | 2011-03-02 | Olympus Corp | ELECTROSTATIC ACTUATOR, BLADDER DEVICE, PICTURE MODULE AND CAMERA |
CN100460983C (zh) * | 2003-08-21 | 2009-02-11 | 奥林巴斯株式会社 | 静电致动器、快门装置、摄像模块以及摄像机 |
JP2005107399A (ja) * | 2003-10-01 | 2005-04-21 | Olympus Corp | ミラー装置 |
CN100570720C (zh) | 2004-07-16 | 2009-12-16 | 三菱化学媒体株式会社 | 光记录介质及光记录介质的光记录方法 |
JP5551914B2 (ja) | 2009-10-14 | 2014-07-16 | 国立大学法人 東京大学 | エレクトレット及びその製造方法並びにエレクトレットを備える静電誘導型変換素子 |
CN103313174B (zh) * | 2012-03-09 | 2016-08-03 | 台湾驻极体电子股份有限公司 | 双层驻极体电声转换装置及具有驻极体扬声器的电子装置 |
JP5855602B2 (ja) * | 2013-05-22 | 2016-02-09 | アオイ電子株式会社 | 静電誘導型電気機械変換素子およびナノピンセット |
-
2015
- 2015-02-13 JP JP2015026839A patent/JP6569933B2/ja active Active
-
2016
- 2016-02-09 US US15/550,215 patent/US10833607B2/en active Active
- 2016-02-09 EP EP16749241.2A patent/EP3244527B1/en active Active
- 2016-02-09 CN CN201680009509.XA patent/CN107251402B/zh active Active
- 2016-02-09 KR KR1020177018341A patent/KR101938506B1/ko active IP Right Grant
- 2016-02-09 WO PCT/JP2016/053836 patent/WO2016129597A1/ja active Application Filing
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004114261A (ja) * | 2002-09-27 | 2004-04-15 | Ntt Electornics Corp | マイクロアクチュエータ装置及びこれを用いた光スイッチシステム |
JP2013013256A (ja) * | 2011-06-29 | 2013-01-17 | Aoi Electronics Co Ltd | エレクトレット膜およびこれを用いた振動発電素子 |
JP5627130B2 (ja) * | 2012-08-30 | 2014-11-19 | アオイ電子株式会社 | 正イオンを含有したエレクトレットの形成方法 |
WO2015019919A1 (ja) * | 2013-08-08 | 2015-02-12 | アオイ電子株式会社 | アクチュエータ、シャッタ装置、流体制御装置、スイッチおよび2次元走査型センサ装置 |
Non-Patent Citations (1)
Title |
---|
See also references of EP3244527A4 * |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109997305A (zh) * | 2016-11-29 | 2019-07-09 | 国立大学法人东京大学 | 振动发电元件 |
CN110036560B (zh) * | 2016-11-29 | 2020-05-15 | 国立大学法人东京大学 | 振动发电装置 |
WO2018101017A1 (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人 東京大学 | 振動発電素子 |
WO2018101047A1 (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人東京大学 | 振動発電デバイス |
JP2018088777A (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人 東京大学 | 振動発電デバイス |
JP2018088780A (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人 東京大学 | 振動発電素子 |
WO2018101046A1 (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人東京大学 | 振動発電デバイス |
CN110036560A (zh) * | 2016-11-29 | 2019-07-19 | 国立大学法人东京大学 | 振动发电装置 |
JP2018088778A (ja) * | 2016-11-29 | 2018-06-07 | 国立大学法人 東京大学 | 振動発電デバイス |
US11552579B2 (en) | 2016-11-29 | 2023-01-10 | The University Of Tokyo | Vibrational energy harvester element |
CN109997305B (zh) * | 2016-11-29 | 2021-05-14 | 国立大学法人东京大学 | 振动发电元件 |
US11081977B2 (en) | 2016-11-29 | 2021-08-03 | The University Of Tokyo | Vibrational energy harvester device |
US11374507B2 (en) | 2016-11-29 | 2022-06-28 | The University Of Tokyo | Vibrational energy harvester device |
JP2022082718A (ja) * | 2021-02-04 | 2022-06-02 | 国立大学法人 東京大学 | 振動発電素子 |
JP2021069280A (ja) * | 2021-02-04 | 2021-04-30 | 国立大学法人 東京大学 | 振動発電素子 |
Also Published As
Publication number | Publication date |
---|---|
CN107251402A (zh) | 2017-10-13 |
KR20170094278A (ko) | 2017-08-17 |
US20180041140A1 (en) | 2018-02-08 |
KR101938506B1 (ko) | 2019-01-14 |
JP2016149914A (ja) | 2016-08-18 |
EP3244527A1 (en) | 2017-11-15 |
JP6569933B2 (ja) | 2019-09-04 |
CN107251402B (zh) | 2019-06-28 |
US10833607B2 (en) | 2020-11-10 |
EP3244527B1 (en) | 2020-10-28 |
EP3244527A4 (en) | 2018-10-17 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6569933B2 (ja) | エレクトレット素子、電気機械変換器およびエレクトレット素子の製造方法 | |
Conrad et al. | A small-gap electrostatic micro-actuator for large deflections | |
WO2014188738A1 (ja) | 静電誘導型電気機械変換素子およびナノピンセット | |
WO2018101017A1 (ja) | 振動発電素子 | |
Sugiyama et al. | SiO2 electret generated by potassium ions on a comb-drive actuator | |
Honma et al. | Improvement of energy conversion effectiveness and maximum output power of electrostatic induction-type MEMS energy harvesters by using symmetric comb-electrode structures | |
CN110036560B (zh) | 振动发电装置 | |
Hagiwara et al. | Soft X-ray charging method for a silicon electret condenser microphone | |
JP5798992B2 (ja) | 静電誘導型変換装置およびdc−dcコンバータ | |
JP2017028868A (ja) | 半導体装置およびその製造方法、および発電システム | |
JP6750822B2 (ja) | エレクトレット素子、電気機械変換器およびエレクトレット素子の製造方法 | |
Boisseau et al. | New DRIE-patterned electrets for vibration energy harvesting | |
US9407172B2 (en) | Vibration power generator | |
JP2013240139A (ja) | 静電型変換装置、静電型トランスおよび交流電圧発生装置 | |
Sugiyama et al. | SiO 2 electret induced by potassium ions on a comb-drive actuator | |
Mitsuya et al. | A Method to Determine the Electret Charge Potential of MEMS Vibrational Energy Harvester Using Pure-White Noise | |
US20220224253A1 (en) | Electrostatic Device and Method for Manufacturing Electrostatic Device | |
Murakami et al. | Characterization of piezoelectric MEMS vibration energy harvesters using random vibration | |
Mitsuya et al. | An Electrostatic Vibrational Mems Energy Harvester of Large Power Recovery Effctiveness Over 92% | |
Hayashi et al. | Electrostatic micro transformer using potassium ion electret forming on a comb-drive actuator | |
Sangouard | Device, Electronic, Technology for a MEMS Which Allow the Extraction Oof Vacuum Energy | |
JP2023076648A (ja) | 振動発電素子 | |
Suzuki et al. | Fabrication of narrow comb-shaped electret by removing charge using excimer laser beam from charge-implanted CYTOP film for avoiding electrostatic repulsion problem | |
Hassan et al. | A theoretical investigation of a two-degree-of-freedom vibro-impact triboelectric energy harvester for larger bandwidth | |
Honma et al. | MEMS Electrostatic Energy Harvester Developed by Simultaneous Process for Anodic Bonding and Electret Charging. |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 16749241 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 20177018341 Country of ref document: KR Kind code of ref document: A |
|
REEP | Request for entry into the european phase |
Ref document number: 2016749241 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 15550215 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |