WO2011152192A1 - Variable capacitance element - Google Patents

Variable capacitance element Download PDF

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Publication number
WO2011152192A1
WO2011152192A1 PCT/JP2011/061146 JP2011061146W WO2011152192A1 WO 2011152192 A1 WO2011152192 A1 WO 2011152192A1 JP 2011061146 W JP2011061146 W JP 2011061146W WO 2011152192 A1 WO2011152192 A1 WO 2011152192A1
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Prior art keywords
capacitance forming
side capacitance
voltage
forming portion
driving
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PCT/JP2011/061146
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French (fr)
Japanese (ja)
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小中義宏
丹羽亮介
吉田康一
吉田順一
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株式会社村田製作所
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Publication of WO2011152192A1 publication Critical patent/WO2011152192A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G5/00—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture
    • H01G5/16—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture using variation of distance between electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • B81B3/0002—Arrangements for avoiding sticking of the flexible or moving parts
    • B81B3/0008—Structures for avoiding electrostatic attraction, e.g. avoiding charge accumulation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/02—Sensors
    • B81B2201/0221—Variable capacitors

Definitions

  • the present invention relates to a variable capacitance element capable of changing a capacitance by using a MEMS driven by electrostatic force.
  • MEMS driven by electrostatic force may be used as an electrostatic drive actuator (see Patent Document 1).
  • FIG. 1 is a diagram for explaining a configuration example of a switch composed of a conventional electrostatic drive actuator.
  • the switch 110 includes a movable plate 120, a folding spring 122, an anchor 124, a substrate 112, a bottom electrode 114, and a signal line 118.
  • the signal line 118 is provided with an electrode gap at a position facing the movable plate 120.
  • the movable plate 120 is a rectangular flat plate made of a conductive material, and one end of a folding spring 122 is connected to four corners. The other end of the folding spring 122 is connected to the anchor 124.
  • the anchor 124 is joined to the substrate 112, and supports the movable plate 120 and the folding spring 122 in a state of being lifted from the substrate 112.
  • a driving DC voltage is applied between the bottom electrode 114 and the movable plate 120, and the movable plate 120 is attracted to the substrate 112 by electrostatic attraction acting by the driving DC voltage.
  • the electrode gap provided in the signal line 118 is conducted through the movable plate 120, and the signal line is switched from the disconnected state to the connected state.
  • an electrostatic drive actuator is configured to generate a capacitance by providing a dielectric film at a position to be an electrical contact and switch the capacitance value. It may be used as a variable capacitance element.
  • a substrate or an insulating film may be charged by a driving DC voltage or the like (hereinafter, this phenomenon is referred to as charge-up) in a portion where an interval between opposed electrodes is narrow.
  • charge-up a sticking phenomenon may occur that the movable plate sticks to the substrate and the MEMS operation cannot be performed properly.
  • the force (elastic force) of the spring that supports the movable plate needs to be large enough to resist charge-up.
  • a drive DC voltage needs to be increased in order to make contact or close, and a large-scale booster circuit is required, which increases costs.
  • an object of the present invention is to provide a variable capacitance element that can prevent malfunction of the MEMS due to charge-up without increasing the drive DC voltage.
  • variable capacitance element includes a plurality of beam-side capacitance forming portions, and a plurality of beam-side capacitance forming portions, and a support portion that supports any of the plurality of beam-side capacitance forming portions.
  • a movable beam that bends and deforms in a direction perpendicular to the arrangement of the forming parts;
  • a housing for accommodating the movable beam in the internal space;
  • a plurality of fixed-side capacitance forming portions that are provided in the internal space of the housing and face each other in the bending direction of the plurality of beam-side capacitance forming portions, and form a capacitance with the beam-side capacitance forming portion, respectively;
  • a variable capacitance element that deflects a movable beam in a bending direction by applying a predetermined driving DC voltage between any of the beam-side capacitance forming portions and a fixed-side capacitance forming portion facing the beam-side capacitance forming portion.
  • the internal space is in a reduced-pressure atmosphere, and when a driving DC voltage is applied, the beam-side capacitance forming portion other than the beam-side capacitance forming portion supported by the support portion is in a state of facing the fixed-side capacitance forming portion and supported by the support portion.
  • the beam-side capacitance forming portion is in a non-facing state to the fixed-side capacitance forming portion so that the displacement of the movable beam passes too far in the non-application state due to the change from the application state of the drive DC voltage to the non-application state. Has been.
  • the mechanical Q value of the movable beam is increased by making the internal space of the housing a reduced pressure atmosphere.
  • the beam-side capacitance forming portion supported by the support portion not to face the fixed-side capacitance forming portion even when the driving DC voltage is applied, the electric field generated between the two is reduced, Charge up at this part is reduced. Then, when the movable beam tries to return to the initial position by the restoring force of the elastic deformation by switching the application state of the driving DC voltage, the beam-side capacitance forming portion with little charge-up goes past the initial position, that is, overshoots.
  • the kinetic energy of the movable beam increases as the beam-side capacitance forming portion having a large charge-up is separated from the fixed-side capacitance forming portion. From the above, it is possible to suppress the occurrence of sticking phenomenon due to charge-up without increasing the spring constant of the movable beam and without increasing the drive DC voltage, and to obtain a highly reliable and low-cost variable capacitance element. be able to.
  • the mechanical Q value of the movable beam is increased by setting the internal space of the housing to a reduced-pressure atmosphere, and the beam-side capacitance forming portion supported by the support portion is applied with the drive DC voltage.
  • the charge-up at this portion is reduced.
  • the movable beam is separated from the fixed-side capacitance forming portion, and sticking by charge-up is performed without increasing the spring constant of the movable beam and without increasing the driving DC voltage. The occurrence of the phenomenon can be suppressed, and a variable capacitor having high reliability and low cost can be obtained.
  • variable capacitor A configuration example of a variable capacitor according to an embodiment of the present invention will be described with reference to the drawings.
  • an orthogonal coordinate XYZ axis is attached, the thickness direction of the movable beam is the Z-axis direction, the principal axis direction is the X-axis direction, and the width direction is the Y-axis direction.
  • FIG. 2A is an XZ sectional view of the variable capacitance element 1 according to the first embodiment.
  • FIG. 2B is a partial perspective view of the movable beam 3 included in the variable capacitance element 1.
  • FIG. 2C is a drive circuit diagram of the variable capacitance element 1.
  • the variable capacitance element 1 has a movable beam 3, lower drive electrodes 6A to 6C, upper drive electrodes 7A to 7C, and equipotential electrodes 8A to 8C in a housing formed of a lower substrate 2A, an upper substrate 2B, and a frame 2C.
  • the same potential stoppers 9A to 9C and external connection electrodes 10A to 10C are provided.
  • the lower substrate 2A and the upper substrate 2B are glass substrates.
  • the frame 2C is formed of a metal film.
  • the inside of the housing composed of the lower substrate 2A, the upper substrate 2B, and the frame 2C is in a reduced pressure atmosphere (about 1000 Pa).
  • the movable beam 3 has a cantilever structure, and has a large mechanical Q value by being housed in a housing under a reduced pressure atmosphere.
  • the movable beam 3 has a structure including beam-side capacitance forming portions 3A to 3C and a support portion 3D formed of a metal film.
  • the support portion 3D is joined to the upper substrate 2B and the lower substrate 2A, functions as an anchor portion of the movable beam 3, and supports the beam side capacitance forming portions 3A to 3C in a state of being separated from the lower substrate 2A and the upper substrate 2B.
  • Each of the beam side capacitance forming portions 3A to 3C is a thick portion (about 10 ⁇ m), and the beam side capacitance is formed from the movable end side (X-axis positive direction side) to the fixed end side (X-axis negative direction side).
  • the portions 3A, the beam-side capacitance forming portion 3B, and the beam-side capacitance forming portion 3C are arranged in this order, and are connected to each other through a thin (about 3 ⁇ m) portion.
  • Lower drive electrodes 6A to 6C and equipotential electrodes 8A to 8C are formed on the upper surface of lower substrate 2A.
  • the upper drive electrodes 7A to 7C and the same potential stoppers 9A to 9C are formed on the lower surface of the upper substrate 2B.
  • the lower drive electrodes 6A to 6C and the upper drive electrodes 7A to 7C are fixed side capacitance forming portions.
  • the lower drive electrode 6A and the upper drive electrode 7A are arranged so as to face each other, and the beam-side capacitance forming portion 3A is arranged at a position sandwiched between both electrodes.
  • the lower drive electrode 6B and the upper drive electrode 7B are also arranged so as to face each other, and the beam-side capacitance forming portion 3B is arranged at a position sandwiched between both electrodes.
  • the lower drive electrode 6C and the upper drive electrode 7C are also arranged to face each other, and the beam-side capacitance forming portion 3C is arranged at a position sandwiched between both electrodes.
  • the equipotential electrode 8A is disposed on the side of the lower drive electrode 6A on the X axis positive direction side, and faces the periphery of the end of the beam side capacitance forming portion 3A on the X axis positive direction side.
  • a stopper portion 11A that protrudes toward the same potential electrode 8A is provided at a position where the beam side capacitance forming portion 3A faces the same potential electrode 8A.
  • the equipotential electrode 8B is disposed on both sides of the lower drive electrode 6B in the X-axis direction, and is opposed to the periphery of both ends in the X-axis direction of the beam side capacitance forming portion 3B.
  • a stopper portion 11B that protrudes toward the same potential electrode 8B is provided at a position where the beam side capacitance forming portion 3B faces the same potential electrode 8B.
  • the equipotential electrode 8C is arranged on the side of the lower drive electrode 6C on the X axis negative direction side, and faces the periphery of the end of the beam side capacitance forming portion 3C in the X axis negative direction.
  • a stopper portion 11C that protrudes toward the same potential electrode 8C is provided at a position where the beam side capacitance forming portion 3C faces the same potential electrode 8C.
  • Each of the stopper portions 11A to 11C is in contact with the opposite equipotential electrodes 8A to 8C, thereby securing a gap space between the beam side capacitance forming portions 3A to 3C and the lower drive electrodes 6A to 6C.
  • the beam side capacitance forming portions 3A to 3C and the equipotential electrodes 8A to 8C are brought into conduction through .about.11C.
  • the same potential stopper 9A is disposed on the side of the X-axis positive direction side of the upper drive electrode 7A so as to protrude from the upper drive electrode 7A toward the beam side capacitance forming portion 3A side. It faces the periphery of the end on the X axis positive direction side.
  • the same potential stopper 9B is arranged on both sides in the X-axis direction of the upper drive electrode 7B so as to protrude from the upper drive electrode 7B to the beam side capacitance forming portion 3B side. It faces the periphery of both ends in the axial direction.
  • the same potential stopper 9C is arranged on the side of the X-axis negative direction side of the upper drive electrode 7C so as to protrude from the upper drive electrode 7C to the beam side capacitance forming portion 3C side. It faces the periphery of the end in the negative direction of the X axis.
  • Each of the equipotential stoppers 9A to 9C is in contact with the opposite beam side capacitance forming portions 3A to 3C, thereby securing a gap space between the beam side capacitance forming portions 3A to 3C and the upper drive electrodes 7A to 7C. Conduction is made to the beam side capacitance forming portions 3A to 3C.
  • External connection electrodes 10A to 10C are formed on the lower surface of the lower substrate 2A and are used for mounting the variable capacitance element 1.
  • Each external connection electrode 10A to 10C is connected to each electrode inside the housing and the movable beam 3 through a through electrode provided on the lower substrate 2A.
  • the configuration of the drive circuit of the variable capacitance element 1 will be described based on a connection configuration example showing an equivalent circuit configuration in FIG.
  • the configuration of the drive circuit is not limited to this example.
  • the equivalent capacitance + Cac formed between the lower drive electrode 6A and the lower drive electrode 6C and the movable beam 3, and the upper drive electrode 7A and the upper drive electrode 7C are connected to each other.
  • An equivalent capacitance -Cac formed between the movable beam 3 and the movable beam 3 is connected to the driving DC voltage source V via the signal cutting resistor R and the switch circuit SW.
  • the capacitor Cb formed between the movable beam 3 and the lower drive electrode 6B is connected to a signal line between the high-frequency signal input terminal RF-IN and the output terminal RF-OUT.
  • the equivalent capacitance + Cac or the equivalent capacitance ⁇ Cac is selected so as to function as a drive capacitance that controls the MEMS operation of the variable capacitance element 1, and the capacitance Cb is the variable capacitance element 1. It functions as a variable capacitor (RF capacitor) to be controlled.
  • FIG. 3 is a partially enlarged view of the internal space of the housing in the variable capacitance element 1.
  • the switch circuit SW is not connected and both the capacitors + Cac and ⁇ Cac are turned off, the movable beam 3 becomes flat as shown in FIG. 3A, and the distance between the movable beam 3 and the upper drive electrodes 7A to 7C. , And the distance between the movable beam 3 and the lower drive electrodes 6A to 6C is kept constant.
  • the spring constant and the drive DC voltage of the movable beam 3 are set so that the beam-side capacitance forming portion 3C does not face the lower substrate 2A side completely in this state.
  • the beam-side capacitance forming portion 3C has a large distance from the lower drive electrode 6C, so the applied electric field is small, the charge-up is small, and the electrostatic attractive force acting on the lower drive electrode 6C side is small.
  • the switch SW circuit When the switch SW circuit is connected to the upper drive electrodes 7A and 7C from there and the capacitance + Cac is turned off and the capacitance ⁇ Cac is turned on, the elastic beam is restored to the movable beam 3 and the upper drive electrodes 7A and 7C.
  • the electrostatic attractive force from the side acts to return to the state of FIG.
  • the beam-side capacitance forming portion 3C has a small electrostatic attraction from the lower substrate 2A side due to the charge-up as described above, and is easily separated from the lower substrate 2A as shown in FIG.
  • the beam-side capacitance forming portion 3B and the beam-side capacitance forming portion 3A can be given more kinetic energy to overcome the charge-up, and the beam-side capacitance forming portion 3B and the beam-side capacitance forming portion 3A can be moved from the lower substrate 2A. Can be easily separated.
  • the electrostatic attractive force due to charge-up from the lower substrate 2A side decreases, and conversely, the electrostatic attractive force due to the drive DC voltage from the upper substrate 2B side decreases.
  • the movable beam 3 is drawn toward the upper substrate 2B as shown in FIG.
  • the beam-side capacitance forming portion 3B comes into contact with the same potential stopper 9B and comes into close contact with the upper drive electrode 7B so that the capacitance Cb, that is, the RF capacitance is minimized.
  • the spring constant and the drive DC voltage of the movable beam 3 are set so that the beam-side capacitance forming portion 3C does not face the upper substrate 2B side completely in this state.
  • the beam-side capacitance forming portion 3C has a large distance from the upper drive electrode 7C, so that the applied electric field is small, the charge-up is small, and the electrostatic attractive force from the upper drive electrode 7C is also small. Therefore, when the switch circuit SW is next connected to the lower drive electrodes 6A and 6C to turn on the capacitor + Cac and turn off the capacitor -Cac, the same phenomenon occurs as described above, overcoming the charge-up and the lower substrate 2A side.
  • the movable beam 3 can be displaced.
  • FIG. 4 and 5 are schematic views at each process stage for explaining the manufacturing process of the variable capacitance element 1.
  • a glass substrate 20 to be the lower substrate 2A is prepared, and a glass protective film 21 is formed on the upper surface (see FIG. 4A).
  • an electrode pattern 22 to be the lower drive electrodes 6A to 6C and the same potential electrodes 8A to 8C is formed on the upper surface of the glass protective film 21 (see FIG. 4B).
  • a laminated electrode made of Au / Pt / Cr is used.
  • the first sacrificial layer pattern 23 is formed on the upper surface of the glass protective film 21, the second sacrificial layer pattern 24 is formed on the upper surfaces of the electrode pattern 22 and the first sacrificial layer pattern 23, and the second sacrificial layer pattern 24 is formed.
  • a third sacrificial layer pattern 25 is formed on the upper surface (see FIG. 4C).
  • the first sacrificial layer pattern 23 has the same thickness as the electrode pattern 22.
  • the second sacrificial layer pattern 24 has the same thickness as the distance between the stopper portions 11A to 11C and the electrode pattern 22.
  • the third sacrificial layer pattern 25 has the same thickness as the height of the stopper portions 11A to 11C.
  • Ti is used as a material for the sacrificial layer pattern.
  • the electrode pattern 26 to be the movable beam 3 and the frame 2C is formed on the upper surfaces of the sacrificial layer patterns 23 to 25 and the electrode pattern 22, and the bonding Au pattern 28 is formed on the upper surface of the electrode pattern 26 (FIG. 4 (D).)
  • the electrode pattern 26 is made of Cu.
  • the sacrificial layer patterns 23 to 25 are removed by etching to form a space 29 (see FIG. 4E).
  • hydrofluoric acid is used as an etchant, but other materials may be used as long as they have selectivity capable of removing the sacrifice layer patterns 23 to 25 made of Ti and leaving the electrode pattern 26 made of Cu.
  • the upper substrate 2B side is manufactured independently of the manufacturing process on the lower substrate 2A side described above.
  • an electrode pattern 32 to be the upper drive electrodes 7A to 7C and the same potential stoppers 9A to 9C is formed on the glass substrate 30, and a bonding Au pattern 38 is formed on the electrode pattern 32 (FIG. 5F )reference.).
  • the structure on the upper substrate 2B side and the structure on the lower substrate 2A side are diffusion bonded with the bonding Au patterns 28 and 38 (see FIG. 5G).
  • diffusion bonding is performed in a reduced pressure atmosphere, and the inside space of the housing is set to a reduced pressure atmosphere.
  • variable capacitance element 1 can be manufactured.
  • the present invention can be implemented, but the configuration of the equipotential electrode, the stopper portion, and the equipotential stopper may be any configuration, and the structure of the equipotential stopper and the equipotential electrode is not adopted. Only the structure of the same potential stopper or the structure of the same potential electrode or the stopper portion may be employed instead of employing the structure of the same potential stopper.

Abstract

Provided is a variable capacitance element capable of preventing an MEMS operation failure caused by charge-up without increasing a driving DC voltage. The variable capacitance element (1) is characterized as follows: A movable beam (3) including beam-side capacitance forming portions (3A to 3C) and a support portion (3D) is housed in a chassis. Lower driving electrodes (6A to 6C) and upper driving electrodes (7A to 7C) are provided facing the beam-side capacitance forming portions (3A to 3C). The space inside the chassis is set to a reduced-pressure atmosphere. When a driving DC voltage is applied, the beam-side capacitance forming portions (3A, 3B) are directly faced to the lower driving electrodes (6A, 6B) or the upper driving electrodes (7A, 7B), but the beam-side capacitance forming portion (3C) is not directly faced to the lower driving electrodes (6C) or the upper driving electrodes (7C). The transition from a state in which the driving DC voltage is applied to a state in which the driving DC voltage is not applied makes the displacement of the movable beam (3) overshoot the position in the state in which the driving DC voltage is not applied.

Description

可変容量素子Variable capacitance element
　この発明は、静電力により駆動するＭＥＭＳを用いて容量を変えることができる可変容量素子に関するものである。 The present invention relates to a variable capacitance element capable of changing a capacitance by using a MEMS driven by electrostatic force.
　近年、静電力により駆動するＭＥＭＳが静電駆動アクチュエータとして利用されることがある（特許文献１参照。）。 In recent years, MEMS driven by electrostatic force may be used as an electrostatic drive actuator (see Patent Document 1).
　図１は、従来の静電駆動アクチュエータで構成されるスイッチの構成例を説明する図である。
　スイッチ１１０は、可動板１２０と、折り返しバネ１２２と、アンカー１２４と、基板１１２と、底部電極１１４と、信号ライン１１８とを備える。信号ライン１１８は、可動板１２０と対向する位置に電極間隙部が設けられている。可動板１２０は導電性材料からなる矩形平板であり、四隅に折り返しバネ１２２の一端が接続される。折り返しバネ１２２の他端は、アンカー１２４に接続される。アンカー１２４は基板１１２に接合され、可動板１２０および折り返しバネ１２２を基板１１２から浮き上がらせた状態で支持する。底部電極１１４は可動板１２０との間に駆動ＤＣ電圧が印加されるものであり、その駆動ＤＣ電圧により作用する静電引力により可動板１２０を基板１１２に引き寄せる。この可動板１２０の動作により、信号ライン１１８に設けられた電極間隙部が可動板１２０を介して導通し、信号ラインが断線状態から接続状態に切り替わる。 FIG. 1 is a diagram for explaining a configuration example of a switch composed of a conventional electrostatic drive actuator.
The switch 110 includes a movable plate 120, a folding spring 122, an anchor 124, a substrate 112, a bottom electrode 114, and a signal line 118. The signal line 118 is provided with an electrode gap at a position facing the movable plate 120. The movable plate 120 is a rectangular flat plate made of a conductive material, and one end of a folding spring 122 is connected to four corners. The other end of the folding spring 122 is connected to the anchor 124. The anchor 124 is joined to the substrate 112, and supports the movable plate 120 and the folding spring 122 in a state of being lifted from the substrate 112. A driving DC voltage is applied between the bottom electrode 114 and the movable plate 120, and the movable plate 120 is attracted to the substrate 112 by electrostatic attraction acting by the driving DC voltage. By the operation of the movable plate 120, the electrode gap provided in the signal line 118 is conducted through the movable plate 120, and the signal line is switched from the disconnected state to the connected state.
　また、上述のように電気的接点の接続を切り替える他にも、電気的接点となる位置に誘電体膜を設けて容量を発生させ、その容量値を切り替えるように静電駆動アクチュエータを構成して可変容量素子として利用することもある。 In addition to switching the connection of electrical contacts as described above, an electrostatic drive actuator is configured to generate a capacitance by providing a dielectric film at a position to be an electrical contact and switch the capacitance value. It may be used as a variable capacitance element.
特開２００１－１４３５９４号公報JP 2001-143594 A
　従来の可変容量素子では、対向する電極の間隔が狭い部分で、駆動ＤＣ電圧などによって基板や絶縁膜が帯電（以下、この現象をチャージアップと称する。）することがある。このチャージアップの帯電量によっては、可動板が基板に貼り付いてＭＥＭＳ動作が適切に行えなくなるスティッキング現象が引き起こされることがあった。
　このチャージアップによるスティッキング現象の発生を防ぐためには、可動板を支持するバネの力（弾性力）を、チャージアップに対抗しうる大きさにする必要があるが、その場合、可動板を基板に接触または近接させるために駆動ＤＣ電圧を大きくする必要が生じ、大規模な昇圧回路が必要となってコストアップの要因となる。 In a conventional variable capacitance element, a substrate or an insulating film may be charged by a driving DC voltage or the like (hereinafter, this phenomenon is referred to as charge-up) in a portion where an interval between opposed electrodes is narrow. Depending on the charge amount of this charge-up, a sticking phenomenon may occur that the movable plate sticks to the substrate and the MEMS operation cannot be performed properly.
In order to prevent the occurrence of sticking due to charge-up, the force (elastic force) of the spring that supports the movable plate needs to be large enough to resist charge-up. A drive DC voltage needs to be increased in order to make contact or close, and a large-scale booster circuit is required, which increases costs.
　そこで本発明の目的は、駆動ＤＣ電圧を大きくすることなく、チャージアップによるＭＥＭＳの動作不良を防ぐことができる可変容量素子を提供することにある。 Therefore, an object of the present invention is to provide a variable capacitance element that can prevent malfunction of the MEMS due to charge-up without increasing the drive DC voltage.
　この発明の可変容量素子は、互いに連結して配列される複数の梁側容量形成部と、複数の梁側容量形成部のいずれかを支持する支持部と、を備えて、複数の梁側容量形成部の配列に垂直な方向に撓み変形する可動梁と、
　可動梁を内部空間に収容する筐体と、
　筐体の内部空間に設けられ、複数の梁側容量形成部の撓み方向に対向して、それぞれ梁側容量形成部と容量を形成する複数の固定側容量形成部と、
を備え、
　梁側容量形成部のいずれかと、該梁側容量形成部と対向する固定側容量形成部との間に所定の駆動ＤＣ電圧を印加して可動梁を撓み方向に撓ませる可変容量素子であって、
　内部空間を減圧雰囲気とし、駆動ＤＣ電圧の印加時に、支持部に支持される梁側容量形成部を除く他の梁側容量形成部を固定側容量形成部に正対する状態とし、支持部に支持される梁側容量形成部を固定側容量形成部に非正対な状態とし、駆動ＤＣ電圧の印加状態から非印加状態への変化により可動梁の変位が非印加状態での位置を行き過ぎるようにされている。 The variable capacitance element according to the present invention includes a plurality of beam-side capacitance forming portions, and a plurality of beam-side capacitance forming portions, and a support portion that supports any of the plurality of beam-side capacitance forming portions. A movable beam that bends and deforms in a direction perpendicular to the arrangement of the forming parts;
A housing for accommodating the movable beam in the internal space;
A plurality of fixed-side capacitance forming portions that are provided in the internal space of the housing and face each other in the bending direction of the plurality of beam-side capacitance forming portions, and form a capacitance with the beam-side capacitance forming portion, respectively;
With
A variable capacitance element that deflects a movable beam in a bending direction by applying a predetermined driving DC voltage between any of the beam-side capacitance forming portions and a fixed-side capacitance forming portion facing the beam-side capacitance forming portion. ,
The internal space is in a reduced-pressure atmosphere, and when a driving DC voltage is applied, the beam-side capacitance forming portion other than the beam-side capacitance forming portion supported by the support portion is in a state of facing the fixed-side capacitance forming portion and supported by the support portion. The beam-side capacitance forming portion is in a non-facing state to the fixed-side capacitance forming portion so that the displacement of the movable beam passes too far in the non-application state due to the change from the application state of the drive DC voltage to the non-application state. Has been.
　この構成では、筐体の内部空間を減圧雰囲気とすることで可動梁の機械的Q値が大きくなる。また、支持部に支持される梁側容量形成部を駆動ＤＣ電圧の印加時であっても固定側容量形成部と正対しない状態とすることで、両者の間に発生する電界が小さくなり、この部分でのチャージアップが少なくなる。すると、駆動ＤＣ電圧の印加状態を切り替えることで可動梁が弾性変形の復元力で初期位置に戻ろうとする際に、チャージアップの少ない梁側容量形成部が初期位置を行き過ぎる、すなわちオーバーシュートするようになり、その他のチャージアップが大きな梁側容量形成部が固定側容量形成部から引き離されるほど可動梁の運動エネルギーが大きくなる。以上のことから、可動梁のバネ定数を大きくすることなく、また、駆動ＤＣ電圧を大きくすることなく、チャージアップによるスティッキング現象の発生を抑制でき、信頼性が高く低コストな可変容量素子を得ることができる。 In this configuration, the mechanical Q value of the movable beam is increased by making the internal space of the housing a reduced pressure atmosphere. In addition, by setting the beam-side capacitance forming portion supported by the support portion not to face the fixed-side capacitance forming portion even when the driving DC voltage is applied, the electric field generated between the two is reduced, Charge up at this part is reduced. Then, when the movable beam tries to return to the initial position by the restoring force of the elastic deformation by switching the application state of the driving DC voltage, the beam-side capacitance forming portion with little charge-up goes past the initial position, that is, overshoots. Accordingly, the kinetic energy of the movable beam increases as the beam-side capacitance forming portion having a large charge-up is separated from the fixed-side capacitance forming portion. From the above, it is possible to suppress the occurrence of sticking phenomenon due to charge-up without increasing the spring constant of the movable beam and without increasing the drive DC voltage, and to obtain a highly reliable and low-cost variable capacitance element. be able to.
　なお、梁側容量形成部を挟んで対向するように配置される２つの固定側容量部に対して、駆動ＤＣ電圧の印加状態と駆動ＤＣ電圧の非印加状態とを排他的に切り替えて、可動梁の撓み方向を切り替えると好適である。 In addition, it is possible to switch between the application state of the drive DC voltage and the non-application state of the drive DC voltage exclusively for the two fixed-side capacitor portions arranged so as to face each other with the beam-side capacitor formation portion interposed therebetween. It is preferable to switch the bending direction of the beam.
　この発明によれば、筐体の内部空間を減圧雰囲気とすることで可動梁の機械的Q値が大きくなり、支持部に支持される梁側容量形成部を駆動ＤＣ電圧の印加時であっても固定側容量形成部と正対しない状態とすることで、この部分でのチャージアップが少なくなる。すると、チャージアップが有っても可動梁が固定側容量形成部から引き離されるようになり、可動梁のバネ定数を大きくすることなく、また、駆動ＤＣ電圧を大きくすることなく、チャージアップによるスティッキング現象の発生を抑制でき、信頼性が高く低コストな可変容量素子を得ることができる。 According to the present invention, the mechanical Q value of the movable beam is increased by setting the internal space of the housing to a reduced-pressure atmosphere, and the beam-side capacitance forming portion supported by the support portion is applied with the drive DC voltage. However, by not facing the fixed-side capacitance forming portion, the charge-up at this portion is reduced. Then, even if there is a charge-up, the movable beam is separated from the fixed-side capacitance forming portion, and sticking by charge-up is performed without increasing the spring constant of the movable beam and without increasing the driving DC voltage. The occurrence of the phenomenon can be suppressed, and a variable capacitor having high reliability and low cost can be obtained.
従来の静電駆動アクチュエータで構成されるスイッチの構成例を説明する図である。It is a figure explaining the structural example of the switch comprised with the conventional electrostatic drive actuator. 本発明の第１の実施形態に係る可変容量素子の構成例を説明する図である。It is a figure explaining the structural example of the variable capacitance element which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係る可変容量素子の動作を説明する図である。It is a figure explaining operation | movement of the variable capacitance element which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係る可変容量素子の製造プロセスを説明する図である。It is a figure explaining the manufacturing process of the variable capacitance element which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係る可変容量素子の製造プロセスを説明する図である。It is a figure explaining the manufacturing process of the variable capacitance element which concerns on the 1st Embodiment of this invention.
　本発明の実施形態に係る可変容量素子の構成例について図を参照して説明する。なお、各図には直交座標形のＸ－Ｙ－Ｚ軸を付し、可動梁の厚み方向をＺ軸方向、主軸方向をＸ軸方向、幅方向をＹ軸方向とする。 A configuration example of a variable capacitor according to an embodiment of the present invention will be described with reference to the drawings. In each figure, an orthogonal coordinate XYZ axis is attached, the thickness direction of the movable beam is the Z-axis direction, the principal axis direction is the X-axis direction, and the width direction is the Y-axis direction.
《第１の実施形態》
　図２（Ａ）は、第１の実施形態に係る可変容量素子１のＸ－Ｚ断面図である。図２（Ｂ）は、可変容量素子１が備える可動梁３の部分斜視図である。図２（Ｃ）は、可変容量素子１の駆動回路図である。 << First Embodiment >>
FIG. 2A is an XZ sectional view of the variable capacitance element 1 according to the first embodiment. FIG. 2B is a partial perspective view of the movable beam 3 included in the variable capacitance element 1. FIG. 2C is a drive circuit diagram of the variable capacitance element 1.
　可変容量素子１は、下基板２Ａと上基板２Ｂと枠体２Ｃとから成る筐体の内部に、可動梁３と下駆動電極６Ａ～６Ｃと上駆動電極７Ａ～７Ｃと同電位電極８Ａ～８Ｃと同電位ストッパ９Ａ～９Ｃと外部接続電極１０Ａ～１０Ｃとを設けた構成である。 The variable capacitance element 1 has a movable beam 3, lower drive electrodes 6A to 6C, upper drive electrodes 7A to 7C, and equipotential electrodes 8A to 8C in a housing formed of a lower substrate 2A, an upper substrate 2B, and a frame 2C. The same potential stoppers 9A to 9C and external connection electrodes 10A to 10C are provided.
　下基板２Ａおよび上基板２Ｂは、ガラス基板である。枠体２Ｃは、金属膜で形成されている。下基板２Ａと上基板２Ｂと枠体２Ｃとから成る筐体の内部は、減圧雰囲気（約１０００Ｐａ）とされている。可動梁３は片持ち梁構造のものであり、減圧雰囲気下の筐体内部に収容されることで機械的Ｑ値が大きなものとなる。 The lower substrate 2A and the upper substrate 2B are glass substrates. The frame 2C is formed of a metal film. The inside of the housing composed of the lower substrate 2A, the upper substrate 2B, and the frame 2C is in a reduced pressure atmosphere (about 1000 Pa). The movable beam 3 has a cantilever structure, and has a large mechanical Q value by being housed in a housing under a reduced pressure atmosphere.
　また可動梁３は、金属膜で形成された梁側容量形成部３Ａ～３Ｃと支持部３Ｄとを備える構成である。支持部３Ｄは上基板２Ｂおよび下基板２Ａに接合され、可動梁３のアンカー部として機能し、梁側容量形成部３Ａ～３Ｃを下基板２Ａおよび上基板２Ｂから離間した状態で支持する。梁側容量形成部３Ａ～３Ｃはそれぞれ厚肉（約１０μｍ）に形成された部分であり、可動端側（Ｘ軸正方向側）から固定端側（Ｘ軸負方向側）に梁側容量形成部３Ａ、梁側容量形成部３Ｂ、梁側容量形成部３Ｃの順に配列され、薄肉（約３μｍ）な部分を介して互いに連結されている。 The movable beam 3 has a structure including beam-side capacitance forming portions 3A to 3C and a support portion 3D formed of a metal film. The support portion 3D is joined to the upper substrate 2B and the lower substrate 2A, functions as an anchor portion of the movable beam 3, and supports the beam side capacitance forming portions 3A to 3C in a state of being separated from the lower substrate 2A and the upper substrate 2B. Each of the beam side capacitance forming portions 3A to 3C is a thick portion (about 10 μm), and the beam side capacitance is formed from the movable end side (X-axis positive direction side) to the fixed end side (X-axis negative direction side). The portions 3A, the beam-side capacitance forming portion 3B, and the beam-side capacitance forming portion 3C are arranged in this order, and are connected to each other through a thin (about 3 μm) portion.
　下駆動電極６Ａ～６Ｃおよび同電位電極８Ａ～８Ｃは、下基板２Ａの上面に形成される。上駆動電極７Ａ～７Ｃおよび同電位ストッパ９Ａ～９Ｃは、上基板２Ｂの下面に形成される。下駆動電極６Ａ～６Ｃおよび上駆動電極７Ａ～７Ｃは、固定側容量形成部である。下駆動電極６Ａおよび上駆動電極７Ａは互いに対向するように配置されていて、両電極間に挟まれる位置に梁側容量形成部３Ａが配置されている。同様に、下駆動電極６Ｂおよび上駆動電極７Ｂも互いに対向するように配置されていて、両電極間に挟まれる位置に梁側容量形成部３Ｂが配置されている。下駆動電極６Ｃおよび上駆動電極７Ｃも互いに対向するように配置されていて、両電極間に挟まれる位置に梁側容量形成部３Ｃが配置されている。 Lower drive electrodes 6A to 6C and equipotential electrodes 8A to 8C are formed on the upper surface of lower substrate 2A. The upper drive electrodes 7A to 7C and the same potential stoppers 9A to 9C are formed on the lower surface of the upper substrate 2B. The lower drive electrodes 6A to 6C and the upper drive electrodes 7A to 7C are fixed side capacitance forming portions. The lower drive electrode 6A and the upper drive electrode 7A are arranged so as to face each other, and the beam-side capacitance forming portion 3A is arranged at a position sandwiched between both electrodes. Similarly, the lower drive electrode 6B and the upper drive electrode 7B are also arranged so as to face each other, and the beam-side capacitance forming portion 3B is arranged at a position sandwiched between both electrodes. The lower drive electrode 6C and the upper drive electrode 7C are also arranged to face each other, and the beam-side capacitance forming portion 3C is arranged at a position sandwiched between both electrodes.
　同電位電極８Ａは、下駆動電極６ＡのＸ軸正方向側の脇に配置されていて、梁側容量形成部３ＡのＸ軸正方向側の端部周辺と対向している。可動梁３において、梁側容量形成部３Ａが同電位電極８Ａと対向する位置には、同電位電極８Ａ側に突出するストッパ部１１Ａが設けられている。同電位電極８Ｂは、下駆動電極６ＢのＸ軸方向の両脇に配置されていて、梁側容量形成部３ＢのＸ軸方向の両端部周辺と対向している。可動梁３において、梁側容量形成部３Ｂが同電位電極８Ｂと対向する位置には、同電位電極８Ｂ側に突出するストッパ部１１Ｂが設けられている。同電位電極８Ｃは、下駆動電極６ＣのＸ軸負方向側の脇に配置されていて、梁側容量形成部３ＣのＸ軸負方向の端部周辺と対向している。可動梁３において、梁側容量形成部３Ｃが同電位電極８Ｃと対向する位置には、同電位電極８Ｃ側に突出するストッパ部１１Ｃが設けられている。 The equipotential electrode 8A is disposed on the side of the lower drive electrode 6A on the X axis positive direction side, and faces the periphery of the end of the beam side capacitance forming portion 3A on the X axis positive direction side. In the movable beam 3, a stopper portion 11A that protrudes toward the same potential electrode 8A is provided at a position where the beam side capacitance forming portion 3A faces the same potential electrode 8A. The equipotential electrode 8B is disposed on both sides of the lower drive electrode 6B in the X-axis direction, and is opposed to the periphery of both ends in the X-axis direction of the beam side capacitance forming portion 3B. In the movable beam 3, a stopper portion 11B that protrudes toward the same potential electrode 8B is provided at a position where the beam side capacitance forming portion 3B faces the same potential electrode 8B. The equipotential electrode 8C is arranged on the side of the lower drive electrode 6C on the X axis negative direction side, and faces the periphery of the end of the beam side capacitance forming portion 3C in the X axis negative direction. In the movable beam 3, a stopper portion 11C that protrudes toward the same potential electrode 8C is provided at a position where the beam side capacitance forming portion 3C faces the same potential electrode 8C.
　各ストッパ部１１Ａ～１１Ｃは、対向する同電位電極８Ａ～８Ｃに接触することで、梁側容量形成部３Ａ～３Ｃと下駆動電極６Ａ～６Ｃとの間にギャップ空間を確保し、ストッパ部１１Ａ～１１Ｃを介して梁側容量形成部３Ａ～３Ｃと同電位電極８Ａ～８Ｃとを導通させる。 Each of the stopper portions 11A to 11C is in contact with the opposite equipotential electrodes 8A to 8C, thereby securing a gap space between the beam side capacitance forming portions 3A to 3C and the lower drive electrodes 6A to 6C. The beam side capacitance forming portions 3A to 3C and the equipotential electrodes 8A to 8C are brought into conduction through .about.11C.
　同電位ストッパ９Ａは、梁側容量形成部３Ａ側に上駆動電極７Ａよりも突出するようにして上駆動電極７ＡのＸ軸正方向側の脇に配置されていて、梁側容量形成部３ＡのＸ軸正方向側の端部周辺と対向している。同電位ストッパ９Ｂは、梁側容量形成部３Ｂ側に上駆動電極７Ｂよりも突出するようにして上駆動電極７ＢのＸ軸方向の両脇に配置されていて、梁側容量形成部３ＢのＸ軸方向の両端部周辺と対向している。同電位ストッパ９Ｃは、梁側容量形成部３Ｃ側に上駆動電極７Ｃよりも突出するようにして上駆動電極７ＣのＸ軸負方向側の脇に配置されていて、梁側容量形成部３ＣのＸ軸負方向の端部周辺と対向している。 The same potential stopper 9A is disposed on the side of the X-axis positive direction side of the upper drive electrode 7A so as to protrude from the upper drive electrode 7A toward the beam side capacitance forming portion 3A side. It faces the periphery of the end on the X axis positive direction side. The same potential stopper 9B is arranged on both sides in the X-axis direction of the upper drive electrode 7B so as to protrude from the upper drive electrode 7B to the beam side capacitance forming portion 3B side. It faces the periphery of both ends in the axial direction. The same potential stopper 9C is arranged on the side of the X-axis negative direction side of the upper drive electrode 7C so as to protrude from the upper drive electrode 7C to the beam side capacitance forming portion 3C side. It faces the periphery of the end in the negative direction of the X axis.
　各同電位ストッパ９Ａ～９Ｃは、対向する梁側容量形成部３Ａ～３Ｃに接触することで、梁側容量形成部３Ａ～３Ｃと上駆動電極７Ａ～７Ｃとの間にギャップ空間を確保し、梁側容量形成部３Ａ～３Ｃに導通する。 Each of the equipotential stoppers 9A to 9C is in contact with the opposite beam side capacitance forming portions 3A to 3C, thereby securing a gap space between the beam side capacitance forming portions 3A to 3C and the upper drive electrodes 7A to 7C. Conduction is made to the beam side capacitance forming portions 3A to 3C.
　外部接続電極１０Ａ～１０Ｃは、下基板２Ａの下面に形成されていて、可変容量素子１の実装に用いられる。各外部接続電極１０Ａ～１０Ｃは下基板２Ａに設けられた貫通電極を介して、筐体内部の各電極および可動梁３に接続される。 External connection electrodes 10A to 10C are formed on the lower surface of the lower substrate 2A and are used for mounting the variable capacitance element 1. Each external connection electrode 10A to 10C is connected to each electrode inside the housing and the movable beam 3 through a through electrode provided on the lower substrate 2A.
　ここで可変容量素子１の駆動回路の構成について、図２（Ｃ）に等価的な回路構成を示す接続構成例に基づいて説明する。なお、駆動回路の構成はこの例に限られるものではない。ここでは、下駆動電極６Ａと下駆動電極６Ｃとを相互に接続して可動梁３との間に形成される等価容量＋Ｃａｃと、上駆動電極７Ａと上駆動電極７Ｃとを相互に接続して可動梁３との間に形成される等価容量－Ｃａｃとを、信号カット用抵抗Ｒおよびスイッチ回路ＳＷを介して駆動ＤＣ電圧源Ｖに接続する。そして、可動梁３と下駆動電極６Ｂとの間に形成される容量Ｃｂを、高周波信号の入力端子ＲＦ－ＩＮと、出力端子ＲＦ－ＯＵＴとの間の信号ラインに接続する。 Here, the configuration of the drive circuit of the variable capacitance element 1 will be described based on a connection configuration example showing an equivalent circuit configuration in FIG. The configuration of the drive circuit is not limited to this example. Here, the equivalent capacitance + Cac formed between the lower drive electrode 6A and the lower drive electrode 6C and the movable beam 3, and the upper drive electrode 7A and the upper drive electrode 7C are connected to each other. An equivalent capacitance -Cac formed between the movable beam 3 and the movable beam 3 is connected to the driving DC voltage source V via the signal cutting resistor R and the switch circuit SW. The capacitor Cb formed between the movable beam 3 and the lower drive electrode 6B is connected to a signal line between the high-frequency signal input terminal RF-IN and the output terminal RF-OUT.
　このような可変容量素子１の駆動回路では、等価容量＋Ｃａｃまたは等価容量－Ｃａｃが、可変容量素子１のＭＥＭＳ動作を制御する駆動容量として機能するように選択され、容量Ｃｂが可変容量素子１の制御対象である可変容量（ＲＦ容量）として機能することになる。 In such a drive circuit of the variable capacitance element 1, the equivalent capacitance + Cac or the equivalent capacitance −Cac is selected so as to function as a drive capacitance that controls the MEMS operation of the variable capacitance element 1, and the capacitance Cb is the variable capacitance element 1. It functions as a variable capacitor (RF capacitor) to be controlled.
　次に、可変容量素子１の具体的な動作例を説明する。図３は可変容量素子１における筐体内部空間の部分拡大図である。
　前述のスイッチ回路ＳＷを無接続状態として容量＋Ｃａｃ，－Ｃａｃともにオフにすると、図３（Ａ）に示すように可動梁３は平坦状となり、可動梁３と上駆動電極７Ａ～７Ｃとの間隔、および可動梁３と下駆動電極６Ａ～６Ｃとの間隔が、それぞれ一定に保たれる。 Next, a specific operation example of the variable capacitance element 1 will be described. FIG. 3 is a partially enlarged view of the internal space of the housing in the variable capacitance element 1.
When the switch circuit SW is not connected and both the capacitors + Cac and −Cac are turned off, the movable beam 3 becomes flat as shown in FIG. 3A, and the distance between the movable beam 3 and the upper drive electrodes 7A to 7C. , And the distance between the movable beam 3 and the lower drive electrodes 6A to 6C is kept constant.
　この状態からスイッチ回路ＳＷを下駆動電極６Ａ，６Ｃ側に接続して容量＋Ｃａｃをオンにし容量－Ｃａｃをオフにすると、下駆動電極６Ａ，６Ｃとの間に作用する静電引力によって、可動梁３は図３（Ｂ）に示すように下基板２Ａ側に撓む。すると、ストッパ部１１Ｂと同電位電極８Ｂとが接触して梁側容量形成部３Ｂが下駆動電極６Ｂに近接して正対する状態となり、容量Ｃｂ、即ちＲＦ容量が最大となる。本実施形態では、この状態の時に梁側容量形成部３Ｃが完全に下基板２Ａ側に近接して正対しないように可動梁３のバネ定数および駆動ＤＣ電圧を設定している。この状態では、梁側容量形成部３Ｃは下駆動電極６Ｃとの間隔が大きいため作用電界が小さく、チャージアップが少なく下駆動電極６Ｃ側に作用する静電引力が小さい。 In this state, when the switch circuit SW is connected to the lower drive electrodes 6A and 6C, the capacitance + Cac is turned on and the capacitance −Cac is turned off, the movable beam is caused by electrostatic attraction acting between the lower drive electrodes 6A and 6C. 3 is bent toward the lower substrate 2A as shown in FIG. Then, the stopper portion 11B and the same potential electrode 8B come into contact with each other so that the beam side capacitance forming portion 3B comes close to and directly faces the lower drive electrode 6B, and the capacitance Cb, that is, the RF capacitance is maximized. In the present embodiment, the spring constant and the drive DC voltage of the movable beam 3 are set so that the beam-side capacitance forming portion 3C does not face the lower substrate 2A side completely in this state. In this state, the beam-side capacitance forming portion 3C has a large distance from the lower drive electrode 6C, so the applied electric field is small, the charge-up is small, and the electrostatic attractive force acting on the lower drive electrode 6C side is small.
　そこからスイッチＳＷ回路を上駆動電極７Ａ，７Ｃ側に接続して容量＋Ｃａｃをオフにし容量－Ｃａｃをオンにすると、可動梁３には弾性変形の復元力が作用するとともに上駆動電極７Ａ，７Ｃ側からの静電引力が作用することにより、図３（Ａ）の状態に戻ろうとする。この際、前述のように梁側容量形成部３Ｃはチャージアップによる下基板２Ａ側からの静電引力が小さく、図３（Ｃ）に示すように下基板２Ａから容易に離れることになる。 When the switch SW circuit is connected to the upper drive electrodes 7A and 7C from there and the capacitance + Cac is turned off and the capacitance −Cac is turned on, the elastic beam is restored to the movable beam 3 and the upper drive electrodes 7A and 7C. The electrostatic attractive force from the side acts to return to the state of FIG. At this time, the beam-side capacitance forming portion 3C has a small electrostatic attraction from the lower substrate 2A side due to the charge-up as described above, and is easily separated from the lower substrate 2A as shown in FIG.
　この状態では、筐体内部空間が減圧雰囲気であるためエアダンピングによる梁側容量形成部３Ｃの運動エネルギーのロスが非常に小さく、梁側容量形成部３Ｃに図３（Ａ）の初期位置を行き過ぎる、すなわちオーバーシュートするほどの大きな運動エネルギーを持たせることができる。すると、梁側容量形成部３Ｂや梁側容量形成部３Ａにもチャージアップに打ち勝つほど大きな運動エネルギーを持たせることができ、梁側容量形成部３Ｂや梁側容量形成部３Ａを下基板２Ａから容易に離れさせることができる。 In this state, since the internal space of the casing is in a reduced pressure atmosphere, the loss of kinetic energy of the beam side capacitance forming portion 3C due to air damping is very small, and the initial position of FIG. That is, it is possible to have a large kinetic energy enough to overshoot. As a result, the beam-side capacitance forming portion 3B and the beam-side capacitance forming portion 3A can be given more kinetic energy to overcome the charge-up, and the beam-side capacitance forming portion 3B and the beam-side capacitance forming portion 3A can be moved from the lower substrate 2A. Can be easily separated.
　その後、可動梁３の下基板２Ａからの距離が大きくなることで下基板２Ａ側からのチャージアップによる静電引力が小さくなり、逆に、上基板２Ｂ側からの駆動ＤＣ電圧による静電引力が大きくなり、可動梁３は図３（Ｄ）に示すように上基板２Ｂ側に引き寄せられることになる。すると、同電位ストッパ９Ｂに梁側容量形成部３Ｂが接触して上駆動電極７Ｂに近接して正対する状態となり、容量Ｃｂ即ちＲＦ容量が最小となる。本実施形態では、この状態の時に梁側容量形成部３Ｃが完全に上基板２Ｂ側に近接して正対しないように可動梁３のバネ定数および駆動ＤＣ電圧を設定している。この状態では、梁側容量形成部３Ｃは上駆動電極７Ｃとの間隔が大きいため作用電界が小さく、チャージアップが少なく上駆動電極７Ｃからの静電引力も小さい。従って、次にスイッチ回路ＳＷを下駆動電極６Ａ，６Ｃ側に接続して容量＋Ｃａｃをオンにし容量－Ｃａｃをオフにする場合も先ほどと同様の現象が起こり、チャージアップに打ち勝って下基板２Ａ側に可動梁３を変位させることができる。 Thereafter, as the distance from the lower substrate 2A of the movable beam 3 increases, the electrostatic attractive force due to charge-up from the lower substrate 2A side decreases, and conversely, the electrostatic attractive force due to the drive DC voltage from the upper substrate 2B side decreases. As the size of the movable beam 3 increases, the movable beam 3 is drawn toward the upper substrate 2B as shown in FIG. Then, the beam-side capacitance forming portion 3B comes into contact with the same potential stopper 9B and comes into close contact with the upper drive electrode 7B so that the capacitance Cb, that is, the RF capacitance is minimized. In this embodiment, the spring constant and the drive DC voltage of the movable beam 3 are set so that the beam-side capacitance forming portion 3C does not face the upper substrate 2B side completely in this state. In this state, the beam-side capacitance forming portion 3C has a large distance from the upper drive electrode 7C, so that the applied electric field is small, the charge-up is small, and the electrostatic attractive force from the upper drive electrode 7C is also small. Therefore, when the switch circuit SW is next connected to the lower drive electrodes 6A and 6C to turn on the capacitor + Cac and turn off the capacitor -Cac, the same phenomenon occurs as described above, overcoming the charge-up and the lower substrate 2A side. The movable beam 3 can be displaced.
　次に、可変容量素子１の製造プロセスについて説明する。図４，５は可変容量素子１の製造プロセスを説明する各プロセス段階での模式図である。
　まず、下基板２Ａとなるガラス基板２０を用意し、その上面にガラス保護膜２１を成膜する（図４（Ａ）参照。）。 Next, a manufacturing process of the variable capacitance element 1 will be described. 4 and 5 are schematic views at each process stage for explaining the manufacturing process of the variable capacitance element 1.
First, a glass substrate 20 to be the lower substrate 2A is prepared, and a glass protective film 21 is formed on the upper surface (see FIG. 4A).
　次に、ガラス保護膜２１の上面に下駆動電極６Ａ～６Ｃや同電位電極８Ａ～８Ｃとなる電極パターン２２を形成する（図４（Ｂ）参照。）。ここでは、Au/Pt/Crからなる積層電極を用いている。 Next, an electrode pattern 22 to be the lower drive electrodes 6A to 6C and the same potential electrodes 8A to 8C is formed on the upper surface of the glass protective film 21 (see FIG. 4B). Here, a laminated electrode made of Au / Pt / Cr is used.
　次に、ガラス保護膜２１の上面に第１犠牲層パターン２３を形成し、電極パターン２２および第１犠牲層パターン２３の上面に第２犠牲層パターン２４を形成し、第２犠牲層パターン２４の上面に第３犠牲層パターン２５を形成する（図４（Ｃ）参照。）。なお、第１犠牲層パターン２３は電極パターン２２と同じ厚みとする。第２犠牲層パターン２４はストッパ部１１Ａ～１１Ｃと電極パターン２２との間の間隔と同じ厚みとする。第３犠牲層パターン２５はストッパ部１１Ａ～１１Ｃの高さと同じ厚みとする。ここでは、犠牲層パターンの材料としてTiを用いている。 Next, the first sacrificial layer pattern 23 is formed on the upper surface of the glass protective film 21, the second sacrificial layer pattern 24 is formed on the upper surfaces of the electrode pattern 22 and the first sacrificial layer pattern 23, and the second sacrificial layer pattern 24 is formed. A third sacrificial layer pattern 25 is formed on the upper surface (see FIG. 4C). The first sacrificial layer pattern 23 has the same thickness as the electrode pattern 22. The second sacrificial layer pattern 24 has the same thickness as the distance between the stopper portions 11A to 11C and the electrode pattern 22. The third sacrificial layer pattern 25 has the same thickness as the height of the stopper portions 11A to 11C. Here, Ti is used as a material for the sacrificial layer pattern.
　次に、各犠牲層パターン２３～２５および電極パターン２２の上面に、可動梁３や枠体２Ｃとなる電極パターン２６を形成し、電極パターン２６の上面に接合用Auパターン２８を形成する（図４（Ｄ）参照。）。電極パターン２６はCuで構成している。 Next, the electrode pattern 26 to be the movable beam 3 and the frame 2C is formed on the upper surfaces of the sacrificial layer patterns 23 to 25 and the electrode pattern 22, and the bonding Au pattern 28 is formed on the upper surface of the electrode pattern 26 (FIG. 4 (D).) The electrode pattern 26 is made of Cu.
　次に、犠牲層パターン２３～２５をエッチングにより除去して空間２９を形成する（図４（Ｅ）参照。）。本実施形態ではエッチャントとしてフッ酸を用いるが、Tiからなる犠牲層パターン２３～２５を除去しCuからなる電極パターン２６を残すことができる選択性を持つものであれば他の材料でもかまわない。 Next, the sacrificial layer patterns 23 to 25 are removed by etching to form a space 29 (see FIG. 4E). In this embodiment, hydrofluoric acid is used as an etchant, but other materials may be used as long as they have selectivity capable of removing the sacrifice layer patterns 23 to 25 made of Ti and leaving the electrode pattern 26 made of Cu.
　また、前述の下基板２Ａ側の製造プロセスと独立に上基板２Ｂ側を製造する。下基板２Ａ側と同様、ガラス基板３０に上駆動電極７Ａ～７Ｃや同電位ストッパ９Ａ～９Ｃとなる電極パターン３２を形成し、電極パターン３２に接合用Auパターン３８を形成する（図５（Ｆ）参照。）。 Also, the upper substrate 2B side is manufactured independently of the manufacturing process on the lower substrate 2A side described above. Similarly to the lower substrate 2A side, an electrode pattern 32 to be the upper drive electrodes 7A to 7C and the same potential stoppers 9A to 9C is formed on the glass substrate 30, and a bonding Au pattern 38 is formed on the electrode pattern 32 (FIG. 5F )reference.).
　次に上基板２Ｂ側の構造体と下基板２Ａ側の構造体とを接合用Auパターン２８，３８同士で拡散接合する（図５（Ｇ）参照。）。この際、拡散接合を減圧雰囲気下で行い、筐体内部空間を減圧雰囲気とする。 Next, the structure on the upper substrate 2B side and the structure on the lower substrate 2A side are diffusion bonded with the bonding Au patterns 28 and 38 (see FIG. 5G). At this time, diffusion bonding is performed in a reduced pressure atmosphere, and the inside space of the housing is set to a reduced pressure atmosphere.
　その後、基板薄肉化や、貫通孔の形成、貫通電極や外部接続電極の形成を行う（図５（Ｈ）参照。）。このようにして、可変容量素子１を製造することができる。 Thereafter, the substrate is thinned, through holes are formed, and through electrodes and external connection electrodes are formed (see FIG. 5H). In this way, the variable capacitance element 1 can be manufactured.
　以上の実施形態で説明したように本発明は実施できるが、同電位電極やストッパ部、同電位ストッパの構成は、どのようなものでもよく、同電位ストッパや同電位電極の構造を採用せずに同電位ストッパの構造のみを採用したり、逆に同電位ストッパの構造を採用せずに同電位電極やストッパ部の構造のみを採用してもよい。 As described in the above embodiments, the present invention can be implemented, but the configuration of the equipotential electrode, the stopper portion, and the equipotential stopper may be any configuration, and the structure of the equipotential stopper and the equipotential electrode is not adopted. Only the structure of the same potential stopper or the structure of the same potential electrode or the stopper portion may be employed instead of employing the structure of the same potential stopper.
１…可変容量素子
２Ａ…下基板
２Ｂ…上基板
２Ｃ…枠体
３…可動梁
３Ａ～Ｃ…梁側容量形成部
３Ｄ…支持部
６Ａ～６Ｃ…下駆動電極
７Ａ～７Ｃ…上駆動電極
８Ａ～８Ｃ…同電位電極
９Ａ～９Ｃ…同電位ストッパ
１０Ａ～１０Ｃ…外部接続電極
１１Ａ～１１Ｃ…ストッパ部 DESCRIPTION OF SYMBOLS 1 ... Variable capacitance element 2A ... Lower board | substrate 2B ... Upper board | substrate 2C ... Frame 3 ... Movable beam 3A-C ... Beam side capacity | capacitance formation part 3D ... Support part 6A-6C ... Lower drive electrode 7A-7C ... Upper drive electrode 8A- 8C: equipotential electrodes 9A to 9C ... equipotential stoppers 10A to 10C ... external connection electrodes 11A to 11C ... stopper portion

Claims (2)

  1. 　互いに連結して配列される複数の梁側容量形成部と、前記複数の梁側容量形成部のいずれかを支持する支持部と、を備えて、前記複数の梁側容量形成部の配列に垂直な方向に撓み変形する可動梁と、
    　前記可動梁を内部空間に収容する筐体と、
    　前記筐体の内部空間に設けられ、前記複数の梁側容量形成部の撓み方向に対向して、それぞれ前記梁側容量形成部と容量を形成する複数の固定側容量形成部と、
    を備え、
    　前記梁側容量形成部のいずれかと、該梁側容量形成部と対向する前記固定側容量形成部との間に所定の駆動ＤＣ電圧を印加して前記可動梁を前記撓み方向に撓ませる可変容量素子であって、
    　前記内部空間を減圧雰囲気とし、前記駆動ＤＣ電圧の印加時に、前記支持部に支持される梁側容量形成部を除く他の梁側容量形成部を前記固定側容量形成部に正対する状態とし、前記支持部に支持される梁側容量形成部を前記固定側容量形成部に非正対な状態とし、前記駆動ＤＣ電圧の印加状態から非印加状態への変化により前記可動梁の変位が非印加状態での位置を行き過ぎるようにされていることを特徴とする可変容量素子。     A plurality of beam-side capacitance forming portions arranged in connection with each other; and a support portion that supports any of the plurality of beam-side capacitance forming portions; and perpendicular to the arrangement of the plurality of beam-side capacitance forming portions A movable beam that bends and deforms in any direction,
    A housing for accommodating the movable beam in an internal space;
    A plurality of fixed-side capacitance forming portions that are provided in an internal space of the housing and face each other in a bending direction of the plurality of beam-side capacitance forming portions;
    With
    A variable capacitance that deflects the movable beam in the bending direction by applying a predetermined driving DC voltage between any of the beam-side capacitance forming portions and the fixed-side capacitance forming portion facing the beam-side capacitance forming portion. An element,
    The internal space is in a reduced pressure atmosphere, and when the driving DC voltage is applied, the beam side capacitance forming portion other than the beam side capacitance forming portion supported by the support portion is in a state of facing the fixed side capacitance forming portion, The beam-side capacitance forming portion supported by the support portion is in a non-facing state with respect to the fixed-side capacitance forming portion, and the displacement of the movable beam is not applied due to the change from the application state of the driving DC voltage to the non-application state. A variable capacitance element characterized in that the position in the state is excessively passed.
  2. 　前記梁側容量形成部を挟んで対向するように配置される２つの前記固定側容量部に対して、前記駆動ＤＣ電圧の印加状態と前記駆動ＤＣ電圧の非印加状態とを排他的に切り替えて、前記可動梁の撓み方向を切り替えることを特徴とする、請求項１に記載の可変容量素子。 The driving DC voltage application state and the driving DC voltage non-application state are exclusively switched with respect to the two fixed-side capacitance portions arranged so as to face each other with the beam-side capacitance formation portion interposed therebetween. The variable capacitance element according to claim 1, wherein the bending direction of the movable beam is switched.
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CN106477509A (en) * 2015-09-01 2017-03-08 阿自倍尔株式会社 Fine Machinery device
CN106477508A (en) * 2015-09-01 2017-03-08 阿自倍尔株式会社 Fine Machinery device

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