WO2009016524A1 - Electrostatic actuator - Google Patents

Electrostatic actuator Download PDF

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Publication number
WO2009016524A1
WO2009016524A1 PCT/IB2008/050811 IB2008050811W WO2009016524A1 WO 2009016524 A1 WO2009016524 A1 WO 2009016524A1 IB 2008050811 W IB2008050811 W IB 2008050811W WO 2009016524 A1 WO2009016524 A1 WO 2009016524A1
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WO
WIPO (PCT)
Prior art keywords
electrode
fixed electrode
charge charging
charge
charging portion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2008/050811
Other languages
English (en)
French (fr)
Inventor
Jun-Bo Yoon
Hyun-Ho Yang
Dong-Hun Choi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Korea Advanced Institute of Science and Technology KAIST
Original Assignee
Korea Advanced Institute of Science and Technology KAIST
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Korea Advanced Institute of Science and Technology KAIST filed Critical Korea Advanced Institute of Science and Technology KAIST
Priority to EP08719578A priority Critical patent/EP2093876A1/en
Priority to CN2008800000875A priority patent/CN101542888B/zh
Priority to JP2009525168A priority patent/JP4864141B2/ja
Priority to US12/091,555 priority patent/US8120451B2/en
Publication of WO2009016524A1 publication Critical patent/WO2009016524A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N13/00—Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect

Definitions

  • the present invention relates to a Microelectromechanical System (MEMS), and more particularly to an electrostatic actuator and its driving method and its application components.
  • MEMS Microelectromechanical System
  • a conventional electrostatic actuator drives a moving electrode by applying a voltage to a fixed electrode and a moving electrode fixed to an insulating substrate to excite charges on the fixed electrode and the moving electrode, and electrostatic attraction between the charges. At this time, the moving force of the moving electrode moves to the support portion supporting the moving electrode and the electrostatic attractive force is balanced.
  • Figure 1 is a schematic view of a conventional cantilever type electrostatic actuator. As shown in (a) of Fig. 1, a voltage is applied between the fixed electrode 120 and the moving electrode 130 to cause electric charges to be excited on the fixed electrode 120 and the moving electrode 130, and the moving electrode 130 is driven by electrostatic attraction acting between charges. Instead of directly applying a voltage to the moving electrode 130, a voltage is applied to the moving electrode 130 through the supporting portion 140 electrically connected to the moving electrode 130.
  • the restoring force of the supporting portion 140 acts in the opposite direction to the electrostatic attractive force acting on the electric charge, so that the moving electrode 130 is moved toward the fixed electrode 120 until the restoring force of the supporting portion 140 and the position where the electrostatic attractive force reaches equilibrium.
  • Fig. 1 (b) is a schematic view showing the actuator 100 of Fig. 1 (a).
  • the support portion 140 for suspending the movable electrode 130 at the set position at the opposite position is indicated by a spring.
  • the restoring force of the designed support portion 140 is as small as possible. However, if the restoring force of the support portion 140 is small, the noise resistance and durability of the support portion 140 are deteriorated, and there is a problem that the continuous operation cannot be reliably performed. Summary of the invention
  • an electrostatic actuator comprises a fixed electrode, a charge charging portion insulated from the fixed electrode, and a movable electrode formed in isolation from the fixed electrode and the charge charging portion.
  • the method further includes: an insulating substrate on which a fixed electrode is formed.
  • the method further includes: an insulating layer formed on the fixed electrode, the charge charging portion being formed on the insulating layer, and the moving electrode being formed on the upper portion of the charge charging portion and opposed to the fixed electrode and the charge charging portion.
  • the charge charging portion is formed on the insulating substrate while being separated from the fixed electrode, and the movable electrode is formed on the upper portion of the fixed electrode and the charge charging portion so as to face the fixed electrode and the charge charging portion.
  • the method further includes: an anti-discharge layer formed on a surface of the charge charging portion.
  • the driving voltage is applied between the fixed electrode and the moving electrode, the first electrostatic force between the fixed electrode and the moving electrode and the second electrostatic force between the charged charging portion and the moving electrode are caused by the moving electrode according to the driving voltage. Perform displacement.
  • a part of the moving electrode is displaced according to the first electrostatic force and the second electrostatic force.
  • the first electrostatic force and the second electrostatic force are electrostatic attractive forces, and the movable electrode is displaced in the direction of the fixed electrode.
  • the charge charging unit stores electric charges in advance.
  • a method of driving an electrostatic actuator according to the present invention includes the step of charging a charge to a charge charging portion, and applying a driving voltage between the fixed electrode and the movable electrode.
  • the step of charging the electric charge includes the step of applying a voltage to the electric charge charging portion, and the step of floating the electric charge charging portion charged with the electric charge.
  • the step of charging the electric charge includes the step of charging the electric charge charging portion by a tunneling method by an electric field.
  • the nonvolatile memory of the present invention comprises: a fixed electrode, a charge charging portion insulated from the fixed electrode, and a moving electrode formed in isolation from the fixed electrode and the charge charging portion.
  • the logic circuit component of the present invention comprises: a fixed electrode, a charge charging portion insulated from the fixed electrode, and a moving electrode formed in isolation from the fixed electrode and the charge charging portion.
  • the switch of the present invention includes: a fixed electrode and a contact electrode formed separately from each other, a charge charging portion formed by sandwiching an insulating layer with a fixed electrode, and a movable electrode formed on an upper portion of the fixed electrode, the charge charging portion, and the contact electrode.
  • the driving voltage is applied between the fixed electrode and the moving electrode, the first electrostatic force between the fixed electrode and the moving electrode and the second electrostatic force between the charged charging portion and the moving electrode are caused by the moving electrode according to the driving voltage. Displacement is in contact with the contact electrode.
  • it further includes: a convex portion formed on a portion of the moving electrode that is in contact with the contact electrode. .
  • it further includes: an anti-discharge layer formed on a surface of the charge charging portion.
  • the charge charging unit stores electric charges in advance.
  • the method further includes: an insulating substrate on which the fixed electrode and the contact electrode are formed.
  • the method further includes: a support portion that supports the movable electrode on the insulating substrate.
  • the charge charging portion is composed of any one of a conductor, an oxygen-oxygen-oxygen (Oxide-Nitride-Oxide, ONO), a ferroelectric, and an electret.
  • a conductor an oxygen-oxygen-oxygen (Oxide-Nitride-Oxide, ONO), a ferroelectric, and an electret.
  • ONO oxygen-oxygen-oxygen
  • ferroelectric ferroelectric
  • the present invention provides an electrostatic actuator which has a lower driving voltage and can arbitrarily adjust a driving voltage as compared with a conventional electrostatic actuator.
  • An electrostatic actuator that is durable to external noise and that can reliably operate continuously is also provided.
  • the present invention also provides non-volatile mechanical memories, logic circuits, and gates that utilize electrostatic actuators.
  • FIG. 1 is a schematic view of a conventional cantilever type electrostatic actuator
  • FIG. 2 is a schematic view showing an electrostatic actuator according to a first embodiment of the present invention
  • FIG. 3 is a schematic structural view of an electrostatic actuator according to an embodiment of the present invention.
  • FIG. 4 is a schematic view showing a driving method of an electrostatic actuator according to a first embodiment of the present invention
  • FIG. 5 is a schematic view showing various methods of charging a charge to a charge charging portion of an electrostatic actuator
  • Figure 7 is a graph showing hysteresis of an electrostatic actuator
  • FIG. 8 is a schematic diagram of a logic circuit using an electrostatic actuator in a third embodiment of the present invention
  • FIG. 9 is a schematic diagram of a cantilever type switch according to a fourth embodiment of the present invention.
  • FIG. 10 is a schematic view of an electrostatic switch according to a fifth embodiment of the present invention. detailed description
  • Fig. 2 is a schematic view showing the electrostatic actuator of the first embodiment of the present invention.
  • the electrostatic actuator 200 of the first embodiment of the present invention includes: an insulating substrate 210, a fixed electrode 220 formed on the insulating substrate 210, a charge charging portion 240 insulated from the fixed electrode 220, and a fixed electrode 220.
  • the movable electrode 250 is formed separately from the charge charging portion 240.
  • the electrostatic actuator 200 further includes a support portion 260 that supports the moving electrode 250 on the insulating substrate 210.
  • the support portion 260 is any structure capable of supporting the movable electrode among the existing electrostatic actuators.
  • FIG. 3 shows an exemplary structure of an electrostatic actuator in the first embodiment of the present invention.
  • Figure 3 (a) is a schematic view of a parallel plate electrostatic actuator.
  • the parallel plate type electrostatic actuator includes: an insulating substrate 210, a fixed electrode 220 formed on the insulating substrate 210, and a charge charging portion 240 interposed with the fixed electrode 220 and insulated from the fixed electrode 220, and located in the charge charging portion 240 of The upper movable electrode 250 and the support portion 260 that supports the movable electrode 250 on the upper portion of the charge charging portion 240.
  • the support portion 260 supports the moving electrode 250 on both sides of the moving electrode 250.
  • Figure 3 (b) is a schematic view of a cantilever type electrostatic actuator in accordance with an embodiment of the present invention.
  • the cantilever type electrostatic actuator includes: an insulating substrate 210, a fixed electrode 220, a charge charging portion 240, a moving electrode 250, and a supporting portion 260.
  • the support portion 260 supports the movable electrode 250 on one side of the moving electrode 250.
  • Fig. 3 (c) is a schematic view of a torsion bar type electrostatic actuator according to an embodiment of the present invention.
  • the torsion bar type electrostatic actuator is the same as the parallel plate type electrostatic actuator from the viewpoint that the support portion 260 supports the moving electrode on both sides of the moving electrode 250.
  • the difference is that the moving electrode 250 moves up and down in parallel in the parallel plate type electrostatic actuator, whereas the moving electrode 250 is twisted and moved in the torsion bar type electrostatic actuator.
  • the fixed electrode 220 and the charge charging portion 240 are divided into two portions, respectively, and the twisting direction of the moving electrode 250 can be adjusted.
  • the insulating substrate 210 is preferably made of a glass substrate, a ceramic substrate, a silicon substrate or the like which has insulating properties and can be formed flat with high precision.
  • a fixed electrode 220 is formed on the insulating substrate 210.
  • An insulating layer 230 is formed on the fixed electrode 220, and a charge charging portion 240 is formed thereon.
  • the charge charging portion 240 is insulated from the fixed electrode 220 by the insulating layer 230.
  • the charge charging portion 240 is charged with a voltage applied from the outside. In order to prevent the charged charge from being discharged, an anti-discharge layer may be formed on the surface of the charge charging portion 240.
  • the discharge prevention layer may be composed of any substance that prevents the charged charge from being discharged by contact with air or other metal substances or non-metal substances, and may be composed of, for example, an insulating material widely used in a semiconductor process.
  • the support portion 260 supports the movable electrode 250 over the fixed electrode 220 and the charge charging portion 240.
  • the moving electrode 250 is insulated from the fixed electrode 220 by the insulating substrate 210.
  • the moving electrode 250 is made of a conductive material.
  • the moving electrode 250 may be composed of a dopant doped polysilicon, a semiconductor or a metal conductor.
  • the support portion 260 is for supporting the moving electrode 250 floating on the charge charging portion 240 at a set interval at an opposite position, and adjusting the charge charging The spacing between the electrical portion 240 and the moving electrode 250.
  • the support portion 260 is represented by a structure having a restoring force in the drawing, but in the specific implementation, the moving electrode 250 itself preferably has flexibility and restoring force.
  • the support portion 260 may also be a part of the moving electrode 250.
  • Fig. 4 is a schematic view showing a driving method of the electrostatic actuator 200 according to the first embodiment of the present invention.
  • a certain electric field is generated between the charge charging portion 240 and the moving electrode 250 by charging the electric charge charging portion 240 and trapping the electric charge or by changing the electric charge.
  • the charge charging portion 240 is preferably composed of any one of a conductor, an oxygen-oxygen oxide (Oxide-Nitride-Oxide), and a ferroelectric (a dielectric having semi-permanent polarization).
  • the charge charging portion 240 When the charge charging portion 240 is composed of a conductor, in order to charge the charge, as shown in FIG. 4(a), between the fixed electrode 220 and the charge charging portion 240 and/or between the moving electrode 250 and the charge charging portion 240 Voltage VI. Thus, a positive or negative charge is excited on the charge charging portion 240. Then, if the charge charging portion 240 is brought into a floating state, the electric charge excited on the charge charging portion 240 can be held. In order to change the charge charging portion 240 into an electrically floating state, the charge charging portion 240 may be short-circuited by a mechanical switch or physically applied by a probe and then short-circuited.
  • a voltage V2 is applied between the fixed electrode 220 and the moving electrode 250.
  • the fixed electrode 220 and the moving electrode 250 excite charges having different signs by the voltage V2 applied between the fixed electrode 220 and the moving electrode 250.
  • the voltage V2 is applied to excite the same electric charge on the fixed electrode 220 as the sign of the electric charge excited on the charge charging portion 240.
  • electrostatic attraction between the moving electrode 250 and the charge charging portion 240, and electrostatic attraction between the moving electrode 250 and the fixed electrode 220 are generated.
  • the moving electrode 250 is displaced in the direction of the fixed electrode 220.
  • the moving electrode 250 is moved until the point where the sum of the electrostatic attractive forces and the restoring force of the support portion 260 are balanced.
  • FIG. 5 are diagrams corresponding to (a) of Fig. 4, and are schematic diagrams showing another method of charging electric charge to the charge charging unit 240.
  • the charge charging portion 240 As another method of charging the charge in the charge charging portion 240, there is also a method using a tunneling phenomenon. Law. As shown in FIG. 5(a), when a high voltage is applied between the fixed electrode 220 and the moving electrode 250, a strong electric field is generated between the fixed electrode 220 and the moving electrode 250, and the electric field causes the charge excited on the fixed electrode 220 to be tunneled.
  • the charge charging portion 240 is injected through the insulating layer 230 between the fixed electrode 220 and the charge charging portion 240 by the phenomenon of the wearing phenomenon. In other words, an electric field that penetrates the charge charging unit 240 is formed, and charges are charged into the charge charging unit 240 by the tunneling phenomenon. Since the charge charging portion 240 is charged with electric charge, since the charge charging portion 240 is in a state of being insulated from the outside, the electric charge can be continuously held.
  • the charge charging unit 240 is composed of ONO, as shown in FIG. 5(b), when a high voltage is applied between the fixed electrode 220 and the moving electrode 250, a strong electric field is formed between the fixed electrode 220 and the moving electrode 250, and the electric field is formed.
  • the electric charge excited on the fixed electrode 220 is trapped on the charge charging portion 240 by the insulating layer 230 between the fixed electrode 220 and the charge charging portion 240 by the tunneling phenomenon. That is, by forming an electric field penetrating the charge charging portion 240, the charge is trapped on the charge charging portion 240 by the tunneling phenomenon.
  • the charge charging portion 240 When the charge is captured by the charge charging portion 240, since the charge charging portion 240 is in a state of being insulated from the outside, it is possible to continue to hold the electric charge. In addition, since the trapped charges are different from the conductors, the adjacent charges are physically separated from each other, so even if a charge release path is generated, the charges of all the charge charging portions are not released like the conductors, but only those generated are released. The charge of the path is therefore more conducive to maintaining the charge.
  • the charge charging portion 240 is composed of a ferroelectric (dielectric having semi-permanent polarization), as shown in FIG. 5(c), if a high voltage is applied between the fixed electrode 220 and the moving electrode 250, the fixed electrode 220 is provided. A strong electric field is formed with the moving electrode 250, which polarizes the ferroelectric as the charge charging portion 240. At this time, the polarization formed in the ferroelectric can be maintained even if the applied electric field is removed, and the polarization forms an electric field, thereby generating electrostatic attraction between the charge charging portion 240 and the moving electrode 250, and continues to be maintained.
  • a ferroelectric dielectric having semi-permanent polarization
  • the electric charge, ONO, and ferroelectric are used as the charge charging unit 240.
  • any substance that can be charged or kept polarized is suitable as the charge charging unit 240. This substance is called an electret.
  • the electrostatic actuator 200 according to an embodiment of the present invention is charged by charging in advance.
  • the electric charge on the portion 240 can drive the moving electrode 250 to a desired extent with a driving voltage smaller than the V voltage. For example, when a voltage is applied to the charge charging portion 240 and the moving electrode 250 to charge the charge charging portion 240 in advance, a voltage of about V-V1 can be applied to the fixed electrode 220 and the moving electrode 250 to drive the moving electrode 250.
  • the charged charge can be maintained, so that a smaller driving voltage can be used in the later use step of the product.
  • Drive the electrostatic actuator Thereby, it is not necessary to set the restoring force of the support portion to be low in order to lower the driving voltage, and therefore it is possible to obtain characteristics excellent in sensitivity to peripheral noise and reliability in continuous operation.
  • the support portion 140 needs to be designed to have different thicknesses, widths, or The length, therefore, if the driving voltage is set in advance in the production step of the product, it is impossible to change later.
  • the electrostatic actuator of the present invention adjusts the driving voltage by adjusting the amount of charge charged to the charge charging portion 240, so The drive voltage can be easily adjusted at any time.
  • Fig. 6 is a schematic view showing an electrostatic actuator according to a second embodiment of the present invention.
  • the electrostatic actuator 300 of the second embodiment of the present invention includes: an insulating substrate 310, a fixed electrode 320, a charge charging portion 330, a moving electrode 340, and a supporting portion 350.
  • the charge charging portion 330 is formed on the insulating substrate 310 in isolation from the fixed electrode 320. Since the charge charging portion 330 and the fixed electrode 320 are isolated from each other, they are insulated from each other.
  • the action and driving method of each constituent element are the same as those of the actuator of the first embodiment of the present invention shown in Figs. 2 to 5 .
  • the electrostatic actuator in this embodiment corresponds to the method of charging the electric charge by the tunneling phenomenon by the electric field formed between the fixed electrode 220 and the moving electrode 250 in the foregoing first embodiment, and can be applied to the insulating substrate 310.
  • a strong voltage is applied between the movable electrode 340 and the tunneling phenomenon between the insulating substrate 310 and the charge charging portion 330 to charge the charge charging portion 330.
  • the fixed electrodes 220, 320 and the charge charging portions 230, 330 are vertically stacked and arranged on the same plane.
  • this arrangement is an exemplified structure, and the position is not limited as long as the fixed electrode and the charge charging portion are insulated from each other and electrostatic attraction is generated between the moving electrodes.
  • Fig. 7 is a graph showing the hysteresis phenomenon of the electrostatic actuator.
  • the graph 410 is a graph showing the hysteresis phenomenon of the conventional electrostatic actuator.
  • the vertical axis I of the graph 410 represents, for example, a current that flows when the fixed electrode and the moving electrode are in contact with each other.
  • This current represents a current flowing through the fixed electrode and the moving electrode or a current flowing through the moving electrode and the contact electrode to be described later.
  • the driving voltage is gradually reduced, and when V1-V2 is reached, the moving electrode is restored to the original position.
  • the fixed electrode and the moving electrode are isolated from each other, so that the current does not flow any more.
  • the driving voltage when the moving electrode moves in the direction of the fixed electrode is different from the driving voltage when the original electrode is restored to the original position, and this phenomenon is called hysteresis.
  • the driving voltage when moving the moving electrode toward the fixed electrode is referred to as a pull-in voltage
  • the driving voltage restored to the original position is referred to as a pull-out voltage.
  • Graph 420 is a graph showing the hysteresis phenomenon of the electrostatic actuator of the present invention. Since the electric charge equivalent to the driving voltage VI is previously stored in the charge charging portion, the driving voltage is reduced by the VI level. Thus, the pull-in voltage and the pull-out voltage are also reduced by the VI level.
  • the electrostatic actuator of the present invention has the same principle as described above by adjusting the amount of charge stored in the charge charging portion to arbitrarily adjust the driving voltage. Referring to the graph 420, by appropriately adjusting the driving voltage, the magnitudes of the pull-in voltage and the pull-out voltage are the same and the signs are opposite.
  • the memory needs to store the "0" and "1" states.
  • the state in which the moving electrode 250 is moved toward the fixed electrode 220 is defined as "1", and the moving electrode 250 is not moved.
  • the status is defined as "0". This definition is for illustrative purposes only, and the opposite definition is also possible.
  • the driving voltage of the electrostatic actuator can be adjusted in accordance with the amount of charge charged to the charge charging portion 240. Therefore, by adjusting the amount of charge charged to the charge charging portion 240, the pull-in voltage and the pull-out voltage are the same in size and opposite in sign. In a specific implementation process, those skilled in the art should understand that the magnitudes of the pull-in voltage and the pull-out voltage are not necessarily the same; and the reference of the drive voltage that distinguishes the "0" and "1" states of the memory does not have to be set to 0, and can be based on any value.
  • the driving voltage applied between the fixed electrode 220 and the moving electrode 250 is applied to a voltage higher than V2 and then changed to 0 V, since the voltage is higher than -V2 as a pull-down voltage, the electrode 250 is moved. It is in a state of moving toward the fixed electrode 220 without leaving the fixed electrode 220, maintaining its state. That is, it can maintain the state of "1". Then, by applying the driving voltage to a voltage smaller than -V2 and then changing to 0 V, the moving electrode 250 can be maintained in the state of returning to the original position. That is, the "0" state can be maintained.
  • Fig. 8 (a) is a schematic view schematically showing a logic circuit using an electrostatic actuator according to a third embodiment of the present invention
  • Fig. 8 (b) is a plan view seen from the direction A in Fig. 8 (a).
  • the logic circuit 500 of the present invention includes an insulating substrate 510, fixed electrodes 520 and 530 formed on the insulating substrate, and charge charging portions 540 and 550 insulated from the fixed electrodes 520 and 530, and formed on the fixed electrodes 520 and 530 and the charge and charge unit.
  • the moving electrode 560 on the upper portion of the 540, 550 supports the moving electrode 560 on the support portion 570 on the insulating substrate 510.
  • the fixed electrodes 520, 530 include a first fixed electrode 520 and a second fixed electrode 530
  • the charge charging portions 540, 550 include a first charge charging portion 540 and a second charge charging portion 550.
  • the fixed electrodes 520, 530 and the charge charging portions 540, 550 are formed on the insulating substrate 510.
  • the movable electrode 560 is supported by the support portion 570 on the insulating substrate 510, separated from the fixed electrodes 520 and 530 and the charge charging portions 540 and 550.
  • the support portion 570 is any structure capable of supporting the movable electrode 560 in the conventional electrostatic actuator.
  • the support portion 570 can also be a portion of the moving electrode 560.
  • the insulating substrate 510 is preferably made of a glass substrate, a ceramic substrate, or a silicon substrate which is insulating and can be formed flat with high precision.
  • the charge charging portions 540 and 550 can form an anti-discharge layer on the surface thereof in order to prevent electric charges charged from the outside from being discharged.
  • the moving electrode 560 is composed of a conductive material.
  • the moving electrode 560 is preferably composed of polysilicon or metal which is doped with impurities.
  • the driving sequence of the logic circuit 500 of the present invention is as follows: The first charge charging portion 540 and the second charge charging portion 550 are charged with electric charges. The first charge charging portion 540 and the second charge charging portion 550 are then brought into an electrically floating state. In order to become electrically floating, a voltage source applied for charging is short-circuited by a mechanical switch, or physically short-circuited by applying a voltage using a probe and charging the charge. In order to prevent the charges charged in the charge charging portions 540, 550 from being discharged, it is preferable to form an anti-discharge layer on the surface thereof.
  • a voltage is applied between the first and second fixed electrodes 530, 540 and the moving electrode 560, and electrostatic attraction between the fixed electrodes 530, 540 and the moving electrode 560 acts on the charge charging portions 540, 550 and moves.
  • the sum of the electrostatic attractive forces between the electrodes 560 displaces the moving electrode 560 toward the fixed electrodes 520, 530.
  • the moving electrode 560 can be driven only when a predetermined voltage is applied to both the first and second fixed electrodes 520, 530.
  • Table 1 shows a case where the moving electrode 560 is driven depending on whether or not a voltage is applied to the first fixed electrode 520 and a voltage is applied to the second fixed electrode 530.
  • the case where a voltage is applied to the first fixed electrode 520 and the second fixed electrode 530 is represented by "1”
  • the case where no voltage is applied is represented by "0”
  • the case where the movable electrode 560 is driven is represented by "1”
  • the case of the drive is represented by "0”
  • it can be known that the result in Table 1 is the same as the logical value of the AND gate (AND).
  • the embodiment described in the present specification is an AND logic having two inputs, but this is merely an exemplified embodiment, and the number of inputs can be arbitrarily adjusted by adjusting the number of fixed electrodes.
  • a structure including two charge charging portions has been described here, the number thereof is not limited to two, and any number of charge charging portions may be included.
  • the structure in which the charge charging portions 540 and 550 and the fixed electrodes 520 and 530 are both provided on the insulating substrate 510 has been described here, as long as electrostatic attraction force can be generated between the movable electrode 560 and the movable electrode 560, the position is not Restricted.
  • FIG. 9 is a schematic view of a cantilever type switch according to a fourth embodiment of the present invention.
  • the cantilever type switch 600 of the present invention includes an insulating substrate 610, a fixed electrode 620 and a contact electrode 670 which are formed on the insulating substrate 610, and a charge charging portion 640 insulated from the fixed electrode 620, which is isolated from the fixed electrode 620 and the charge charging portion 640.
  • the formed moving electrode 650 supports the movable electrode 650 on the support portion 660 on the insulating substrate 610, and the convex portion 680.
  • the charge charging portion 640 is charged with electric charge and a driving voltage is applied between the fixed electrode 620 and the moving electrode 650, the moving electrode 650 is displaced toward the fixed electrode 620 to bring the convex portion 680 into contact with the contact electrode 670.
  • the support portion 660, the moving electrode 650, the boss portion 680, and the contact electrode 670 are turned on, and the switch is in an on state.
  • the driving voltage is not applied, the bump 680 is isolated from the contact electrode 670, and the switch is in an off state.
  • the functions of the components of the switch 600 are the same as those of the electrostatic actuator of the present invention described above.
  • the charge charging unit 640 Charge the charge. Then, the charge charging portion 640 is brought into an electrically floating state. In order to become in an electro floating state, the voltage applied to charge the electric charge may be short-circuited by a mechanical switch or by applying a voltage using a probe to charge the probe. In order to prevent the charged charge from being discharged, an anti-discharge layer may be formed on the surface of the charge charging portion 640.
  • a driving voltage equal to or higher than a critical value is applied between the fixed electrode 620 and the moving electrode 650. If a voltage is applied, charges on the fixed electrode 620 and the moving electrode 650 are excited with mutually different signs, and a driving voltage is applied to excite a charge having the same sign on the fixed electrode 620 as the charge charged to the charge charging portion 640. . If a voltage higher than the critical value is applied, the electrostatic attractive force between the fixed electrode 620 and the moving electrode 650 and the electrostatic attractive force between the charge charging portion 640 and the moving electrode 650 cause a portion of the moving electrode 650 to proceed toward the fixed electrode 620. Displacement.
  • the moving electrode When a voltage equal to or lower than the critical value is applied, the moving electrode is restored to the original position by the restoring force of the supporting portion 660 or the moving electrode 650. If the moving electrode 650 is displaced toward the fixed electrode 620, the convex portion 680 formed at the end of the moving electrode 650 comes into contact with the contact electrode 670, causing the switch to be in an on state.
  • a fixed electrode 620 is formed on an insulating substrate 610, and an insulating layer is formed thereon.
  • the position thereof is not limited at all.
  • Fig. 10 is a schematic view showing an electrostatic switch according to another embodiment of the present invention. Referring to Fig. 10, there is shown a structure in which a fixed electrode 720 and a charge charging portion 730 are formed on the insulating substrate 710. As described above, the positions of the charge charging portion 730 and the fixed electrode 720 are exemplified structures, and are not limited to such an arrangement.
  • the electrostatic actuator of the present invention can be applied to a microelectromechanical system. Specifically, the electrostatic actuator of the present invention can be utilized as a non-volatile mechanical memory, logic circuit, and switch.

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Description

.. - 静电致动器 技术领域
本发明涉及微机电系统 (Microelectromechanical System, MEMS), 更具体 为涉及静电致动器 (electrostatic actuator)及其驱动方法及其应用元件。 背景技术
现有的静电致动器， 通过向固定在绝缘基板上的固定电极和移动电极施 加电压以在固定电极和移动电极上激发电荷， 利用作用于电荷之间的静电引 力驱动移动电极。 这时， 移动电极移动至支撑移动电极的支撑部的回复力和 静电引力达到平衡为止。
图 1为现有的悬臂 （cantilever)式静电致动器的示意图。 如图 1中 （a) 所示， 在固定电极 120和移动电极 130之间施加电压， 使在固定电极 120和 移动电极 130上激发电荷，利用作用于电荷之间的静电引力驱动移动电极 130。 可以不直接向移动电极 130施加电压， 而通过与移动电极 130电连接的支撑 部 140向移动电极 130施加电压。 这时， 支撑部 140的回复力朝与作用于电 荷之间的静电引力相反的方向作用， 因此移动电极 130朝固定电极 120方向 移动至支撑部 140的回复力和静电引力达到平衡的地点为止。
图 1中 （b)为概略地表示图 1 (a) 中致动器 100的示意图。 为了使移动 电极 130以设定的间隔悬浮于相对的位置的支撑部 140用弹簧来表示。
为了用低电压驱动致动器 100， 所设计的支撑部 140的回复力尽量要小。 但是如果支撑部 140的回复力小， 则支撑部 140的抗噪音性和耐久性变差， 产生不能可靠地连续动作的问题。 发明内容
本发明的目的是提供一种与现有的静电致动器相比驱动电压很小， 并且 能够任意调节驱动电压的静电致动器。 本发明的另一目的是提供一种对外部 噪音耐久性强、 能够可靠地连续动作的静电致动器。
另外， 本发明的再一目的是提供一种利用本发明一实施例的静电致动器 的非挥发性机械式存储器、 逻辑电路及开关。
为了实现上述目的， 本发明的一种静电致动器， 包括固定电极， 与固定 电极绝缘的电荷充电部， 与固定电极和电荷充电部隔离形成的移动电极。
其中， 优选为： 还包括绝缘基板， 其上形成固定电极。
其中， 优选为： 还包括形成在固定电极上的绝缘层， 电荷充电部形成在 绝缘层之上， 移动电极形成在电荷充电部的上部并且与固定电极和电荷充电 部相对。
其中， 优选为： 电荷充电部与固定电极相隔离而形成在绝缘基板上， 移 动电极与固定电极和电荷充电部相对地形成在固定电极和电荷充电部的上 部。
其中， 优选为： 还包括在电荷充电部表面形成的防放电层。
其中， 优选为： 在固定电极和移动电极之间施加驱动电压， 移动电极根 据驱动电压引起的固定电极与移动电极之间的第一静电力和电荷充电部与移 动电极之间的第二静电力进行位移。
其中， 优选为： 移动电极的一部分根据第一静电力和第二静电力进行位 移。
其中， 优选为： 第一静电力和第二静电力为静电引力， 移动电极朝固定 电极方向进行位移。
其中， 优选为： 电荷充电部预先存储有电荷。
本发明的静电致动器的驱动方法， 包括： 向电荷充电部充入电荷的步骤， 向固定电极和移动电极之间施加驱动电压的步骤。
其中， 优选为： 充入电荷的步骤包括： 向电荷充电部施加电压的步骤， 电浮 （floating) 已充入了电荷的电荷充电部的步骤。 其中， 优选为： 充入电荷的步骤包括： 利用通过电场的隧穿方法向电荷 充电部充入电荷的步骤。
本发明的非挥发性存储器， 包括： 固定电极， 与固定电极绝缘的电荷充 电部， 与固定电极和电荷充电部隔离形成的移动电极。
本发明的逻辑电路元件， 包括： 固定电极， 与固定电极绝缘的电荷充电 部， 与固定电极和电荷充电部隔离形成的移动电极。
本发明的开关， 包括： 相互隔离形成的固定电极和接触电极， 与固定电 极夹着绝缘层而形成的电荷充电部， 在固定电极、 电荷充电部和接触电极的 上部形成的移动电极。
其中， 优选为： 在固定电极和移动电极之间施加驱动电压， 移动电极根 据驱动电压引起的固定电极与移动电极之间的第一静电力和电荷充电部与移 动电极之间的第二静电力进行位移与接触电极接触。
其中， 优选为： 还包括形成在移动电极的与接触电极接触的部位上的凸 起部。 .
其中， 优选为： 还包括形成在电荷充电部的表面上的防放电层。
其中， 优选为： 电荷充电部预先存储有电荷。
其中， 优选为： 还包括绝缘基板， 其上形成固定电极和接触电极。
其中， 优选为： 还包括将移动电极支撑于绝缘基板之上的支撑部。
本发明的静电致动器中， 所述电荷充电部由导电体、 氧氮氧 (Oxide-Nitride-Oxide, ONO) 、 强电介质和驻极体中的任一构成。
本发明提供了与现有的静电致动器相比驱动电压低并能够任意调节驱动 电压的静电致动器。 还提供了对外部噪音的耐久性强、 能够可靠地连续工作 的静电致动器。
另外， 本发明还提供了利用静电致动器的非挥发性机械式存储器、 逻辑 电路和幵关。 附图说明
图 1为现有的悬臂式静电致动器示意图；
图 2为本发明第一实施例的静电致动器的概略示意图；
图 3为本发明一实施例的静电致动器的具体结构示意图；
图 4为本发明第一实施例的静电致动器的驱动方法概略示意图； 图 5为向静电致动器的电荷充电部充入电荷的多种方法的示意图； 图 6为本发明第二实施例的静电致动器的概略示意图；
图 7为表示静电致动器的磁滞现象（hysteresis) 的曲线图；
图 8为本发明第三实施例中利用静电致动器的逻辑电路的概略示意图； 图 9为本发明第四实施例的悬臂式开关示意图；
图 10为本发明第五实施例的静电开关示意图。 具体实施方式
以下参照附图详细说明本发明的较佳实施例。 在全部附图中对于同样的 构成要素以同样的附图标记予以表示。
[静电致动器]
图 2为本发明第一实施例的静电致动器的概略示意图。 如图 2所示， 本 发明第一实施例的静电致动器 200包括： 绝缘基板 210， 形成在绝缘基板 210 上的固定电极 220， 与固定电极 220绝缘的电荷充电部 240， 与固定电极 220 和电荷充电部 240隔离形成的移动电极 250。另外，静电致动器 200还包括将 移动电极 250支撑于绝缘基板 210之上的支撑部 260。其中，支撑部 260为现 有的静电致动器中能够支撑移动电极的任意结构。
图 3表示了本发明第一实施例中静电致动器的例示结构。 图 3 (a) 为平 行板（parallel plate) 式静电致动器的示意图。 平行板式静电致动器包括： 绝 缘基板 210， 形成在绝缘基板 210上的固定电极 220， 与固定电极 220之间夹 设绝缘物质而与固定电极 220绝缘的电荷充电部 240，位于电荷充电部 240的 上部的移动电极 250，以及将移动电极 250支撑于电荷充电部 240上部的支撑 部 260。 支撑部 260在移动电极 250的两侧支撑移动电极 250。
图 3 (b) 为本发明一实施例中悬臂式静电致动器的示意图。 悬臂式静电 致动器包括： 绝缘基板 210， 固定电极 220， 电荷充电部 240， 移动电极 250 及支撑部 260。 其中， 支撑部 260在移动电极 250的一侧支撑移动电极 250。
图 3 (c) 为本发明一实施例的扭杆（torsion bar)式静电致动器示意图。 从支撑部 260在移动电极 250两侧支撑移动电极的观点上， 扭杆式静电致动 器与平行板式静电致动器相同。 不同之处在于， 在平行板式静电致动器中移 动电极 250上下平行移动， 与此相比， 在扭杆式静电致动器中移动电极 250 扭转移动。另外， 固定电极 220、 电荷充电部 240分别分割成两个部分， 能够 调节移动电极 250的扭转方向。
以上， 通过参照图 3， 说明了静电致动器的具体结构。 再参照图 2， 详细 说明本发明的静电致动器的结构。
绝缘基板 210优选由具有绝缘性、并能以高精度平平地形成的玻璃基板、 陶瓷基板或硅基板等构成。在绝缘基板 210上， 形成有固定电极 220。 固定电 极 220上形成有绝缘层 230， 在其上形成有电荷充电部 240。 电荷充电部 240 通过绝缘层 230与固定电极 220绝缘。 电荷充电部 240被从外部施加的电压 充入电荷。 为了防止已充入的电荷被放电， 在电荷充电部 240的表面可以形 成防放电层。 防放电层可以由防止已充入的电荷与空气或其他金属物质或非 金属物质接触而放电的任意物质构成， 例如可以由半导体工序中广泛应用的 绝缘物质构成。 支撑部 260将移动电极 250支撑于固定电极 220和电荷充电 部 240之上。 移动电极 250通过绝缘基板 210与固定电极 220绝缘。 为了使 移动电极 250被固定电极 220及电荷充电部 240与移动电极 250之间产生的 静电引力驱动， 移动电极 250由导电性物质构成。 移动电极 250可以由掺杂 剂掺杂的多晶硅、 半导体或金属等导体构成。 支撑部 260用于支撑在电荷充 电部 240上以设定的间隔在相对的位置漂浮的移动电极 250，并且调节电荷充 电部 240和移动电极 250之间的间隔。 为了有助于理解本发明， 在附图中通 过具有回复力的结构表示了支撑部 260， 但是在具体实施过程中， 移动电极 250本身具有挠性和回复力为佳。另外，支撑部 260还可以为移动电极 250的 一部分。
图 4为本发明第一实施例的静电致动器 200的驱动方法概略示意图。 首 先， 通过向电荷充电部 240充入电荷及捕捉电荷， 或将其变成极化状态， 使 电荷充电部 240和移动电极 250之间产生一定的电场。
其中， 电荷充电部 240优选为由导电体、 氧氮氧 （Oxide-Nitride-Oxide) 和强电介质（具有半永久性极化的电介质） 中的任一所构成。
电荷充电部 240由导电体构成时， 为了充入电荷， 如图 4 (a)所示， 在 固定电极 220与电荷充电部 240之间和 /或在移动电极 250与电荷充电部 240 之间施加电压 VI。如此，在电荷充电部 240上激发出阳电荷或阴电荷。然后， 如果将电荷充电部 240变成电浮 （floating)状态， 则可以保持在电荷充电部 240上激发的电荷。为了将电荷充电部 240变成电浮状态，可以通过机械开关 将电荷充电部 240短路或者利用探针施加电压后以物理方式将其短路。
然后， 如图 4 (b)所示， 向固定电极 220和移动电极 250之间施加电压 V2。如此， 通过向固定电极 220和移动电极 250之间施加的电压 V2， 使固定 电极 220和移动电极 250激发出具有不同符号的电荷。此时，施加电压 V2以 使在固定电极 220上激发出与电荷充电部 240上激发出来的电荷的符号相同 的电荷。 由此， 产生移动电极 250和电荷充电部 240之间的静电引力， 以及 移动电极 250和固定电极 220之间的静电引力。 此时， 若这些静电引力之和 为临界值以上， 则移动电极 250朝固定电极 220方向进行位移。移动电极 250 移动至静电引力之和与支撑部 260的回复力达到平衡的地点为止。
图 5中 （a)至 （c) 为与图 4中 （a)相对应的图， 是向电荷充电部 240 充入电荷的另一种方法的概略示意图。
作为在电荷充电部 240充入电荷的另一种方法， 还有利用隧穿现象的方 法。 如图 5 (a)所示， 在固定电极 220和移动电极 250之间施加高电压， 则 在固定电极 220和移动电极 250之间产生强电场， 该电场使固定电极 220上 激发的电荷在隧穿现象的作用下， 通过固定电极 220和电荷充电部 240之间 的绝缘层 230注入到电荷充电部 240。 即， 形成贯通电荷充电部 240的电场， 利用隧穿现象， 向电荷充电部 240充入电荷。 电荷充电部 240—旦充入电荷， 由于电荷充电部 240处于与外界绝缘的状态， 因此能继续保持电荷。
电荷充电部 240由 ONO构成时， 如图 5 (b)所示， 如果向固定电极 220 和移动电极 250之间施加高电压， 则在固定电极 220和移动电极 250之间形 成强电场， 该电场使固定电极 220上激发出来的电荷在隧穿现象的作用下， 通过固定电极 220和电荷充电部 240之间的绝缘层 230，被捕捉在电荷充电部 240上。 即， 通过形成贯通电荷充电部 240的电场， 利用隧穿现象将电荷捕捉 在电荷充电部 240上。 电荷一旦被电荷充电部 240捕捉时， 由于电荷充电部 240处于与外界绝缘的状态， 因此能够继续保持电荷。另外， 由于被捕捉的电 荷与导电体不同， 相邻的电荷之间物理性相互隔离， 因此即使产生电荷释放 通路， 也不会像导电体一样释放所有电荷充电部的电荷， 只是释放掉那些产 生通路的电荷， 所以更有利于保持电荷。
另外， 电荷充电部 240 由强电介质 （具有半永久性极化的电介质）构成 时， 如图 5 (c)所示， 如果向固定电极 220和移动电极 250之间施加高电压， 则在固定电极 220和移动电极 250之间形成强电场， 该电场使作为电荷充电 部 240的强电介质被极化。 此时， 即使去掉施加的电场也可以保持形成于强 电介质内的极化， 并且该极化形成电场， 因此在电荷充电部 240和移动电极 250之间产生静电引力， 并且继续维持。
以上， 虽然针对以导电体、 ONO和强电介质作为电荷充电部 240时进行 了说明， 但是， 此外只要能够充入电荷或者保持极化现象的物质都适合作为 电荷充电部 240。 这种物质叫做驻极体（electret) 。
本发明的一实施例中的静电致动器 200与现有的致动器 100相比差异点 在于， 现有致动器向固定电极 120和移动电极 130之间施加 V电压才能使移 动电极 130被静电引力移动所需程度； 而本发明一实施例的静电致动器 200 由于预先充入电荷充电部 240上的电荷， 能以比 V电压更小的驱动电压驱动 移动电极 250移动所需程度。 例如， 向电荷充电部 240和移动电极 250施加 VI电压使电荷充电部 240预先充有电荷的情况下， 可以向固定电极 220和移 动电极 250施加 V-V1程度的电压以驱动移动电极 250。在产品的生产步骤或 者在使用步骤， 只要向电荷充电部 240充入一次电荷并将其电浮， 就能保持 充入的电荷， 因此在以后的产品的使用步骤中能够以较小的驱动电压驱动静 电致动器。 由此， 不必为了降低驱动电压而将支撑部的回复力设定得较低， 因此能够获得对周边噪音的敏感性及连续动作的可靠性优秀的特性。
另外， 现有的静电致动器中为了调节驱动电压而需要调节移动电极和固 定电极之间的间隔， 或为了调节支撑部 140的回复力而需要将支撑部 140设 计成不同的厚度、 宽度或长度， 因此， 如果在产品的生产步骤中若预先设定 驱动电压， 则以后不可能改变， 相反本发明的静电致动器通过调节向电荷充 电部 240充入的电荷量来调节驱动电压， 因此不论何时都能轻易地调节驱动 电压。
图 6为本发明第二实施例的静电致动器的概略示意图。 本发明第二实施 例的静电致动器 300包括： 绝缘基板 310， 固定电极 320， 电荷充电部 330， 移动电极 340和支撑部 350。电荷充电部 330与固定电极 320隔离地形成在绝 缘基板 310上。 由于电荷充电部 330和固定电极 320相互隔离， 因此互相绝 缘。 各构成要素的作用及驱动方法与图 2至图 5中所示的本发明第一实施例 的致动器相同。
本实施例中的静电致动器， 与前面的第一实施例中通过在固定电极 220 和移动电极 250之间形成的电场并利用隧穿现象充入电荷的方法相对应， 能 在绝缘基板 310和移动电极 340之间施加强电压， 并利用绝缘基板 310和电 荷充电部 330之间的隧穿现象向电荷充电部 330充入电荷。 在本发明的第一实施例和第二实施例中表示了固定电极 220、 320和电荷 充电部 230、 330为垂直堆积的结构以及设置在同一平面上的结构。 但是这种 设置为例示结构， 只要固定电极和电荷充电部相互绝缘并且与移动电极之间 能产生静电引力， 则其位置不受限制。
[存储器]
以下， 对利用本发明的静电致动器的存储器元件进行说明。 在此之前， 参照图 7， 以说明静电致动器的磁滞现象（hysteresis) 。 图 7为表示静电致动 器的磁滞现象的曲线图。 曲线图 410为表示现有的静电致动器的磁滞现象的 曲线图。 当增加在固定电极和移动电极之间施加的电压而驱动电压达到 V1+V2时， 移动电极朝固定电极方向进行位移。 曲线图 410的纵轴 I表示例 如固定电极和移动电极相互接触时导通而流动的电流。 该电流表示通过固定 电极和移动电极流动的电流或者后述的通过移动电极和接触电极流动的电 流。 此后， 逐渐减小驱动电压， 当达到 V1-V2时， 移动电极复原到原位置。 由此， 固定电极和移动电极相互隔离， 使电流不再流动。 如曲线图 410所示， 移动电极朝固定电极方向移动时的驱动电压和复原到原位置时的驱动电压相 异， 将这种现象称为磁滞现象。 将移动电极朝固定电极方向移动时的驱动电 压称为牵入 （pull-in) 电压， 将复原到原位置的驱动电压称为牵出 （pull-out) 电压。
曲线图 420为表示本发明静电致动器的磁滞现象的曲线图。 由于将与驱 动电压 VI相当程度的电荷预先存储到电荷充电部， 因此驱动电压减小了 VI 程度。 由此， 牵入电压和牵出电压也减小了 VI程度。本发明的静电致动器通 过调节在电荷充电部存储的电荷量来任意地调节驱动电压的原理与前述的相 同。参照曲线图 420， 通过适当地调节驱动电压， 使得将牵入电压和牵出电压 的大小相同、 符号相反。
存储器需要存储 "0"和 "1 "状态， 如图 2的静电致动器中， 将移动电 极 250朝固定电极 220移动的状态定义为 " 1 "， 将移动电极 250没有移动的 状态定义为 "0"。 这种定义仅仅是为了便于说明， 因而与其相反的定义也是 可行的。
如前面所述， 可以根据向电荷充电部 240充电的电荷量调节静电致动器 的驱动电压。 因此， 通过调节向电荷充电部 240充电的电荷量， 使得牵入电 压和牵出电压大小相同、 符号相反。 在具体实施过程中， 本领域技术人员应 当理解： 牵入电压和牵出电压的大小不一定要相同； 并且区分存储器的 "0" 和 " 1 "状态的驱动电压的基准不一定要设定为 0， 而能够以任意值为基准。
若把向固定电极 220和移动电极 250之间施加的驱动电压施加为比 V2更 高的电压之后再换成 0V， 则由于高于作为下拉（pull-down) 电压的 -V2， 因 此移动电极 250处在朝固定电极 220移动的状态而不离幵固定电极 220，维持 其状态。 即， 能维持 " 1 "的状态。 然后， 把驱动电压施加为比 -V2更小的电 压之后再换成 0V， 则移动电极 250能维持在复原到原来位置的状态。 即， 能 维持 "0"状态。
通过这种方式， 施加比 V2更高或者 -V2更低的驱动电压， 则在以后不施 加电压也能够维持 "0"和 " 1 " 的状态， 因此能将本发明的静电致动器利用 于非挥发性机械式存储器。
[逻辑电路]
图 8中 （a) 为概略地表示利用本发明第三实施例的静电致动器的逻辑电 路的示意图， 图 8 ·中 （b) 为图 8中 （a) 的从 A方向观看的俯视图。 本发明 的逻辑电路 500包括：绝缘基板 510，形成于绝缘基板上的固定电极 520、 530, 与固定电极 520、 530绝缘的电荷充电部 540、 550, 形成于固定电极 520、 530 和电荷充电部 540、 550的上部的移动电极 560， 将移动电极 560支撑于绝缘 基板 510上的支撑部 570。
参照图 8中 （b) ， 固定电极 520、 530包括第一固定电极 520和第二固 定电极 530， 电荷充电部 540、 550包括第一电荷充电部 540和第二电荷充电 部 550。 固定电极 520、 530和电荷充电部 540、 550形成在绝缘基板 510上。 移动电极 560与固定电极 520、 530和电荷充电部 540、 550隔离并对置地被 支撑部 570支撑于绝缘基板 510上。 其中， 支撑部 570为现有的静电致动器 中能够支撑移动电极 560的任意结构。 支撑部 570还可以为移动电极 560的 一部分。 绝缘基板 510 由具有绝缘性， 并能够以高精度平平地形成的玻璃基 板、 陶瓷基板或者硅基板等构成为佳。 电荷充电部 540、 550为了防止从外部 充入的电荷被放电，可在其表面形成防放电层。为了利用在固定电极 520、 530 和电荷充电部 540、 550与移动电极 560之间产生的静电引力驱动移动电极 560, 移动电极 560由导电性物质构成。 移动电极 560优选由掺杂剂惨杂的多 晶硅或者金属构成。
本发明的逻辑电路 500的驱动顺序如下： 向第一电荷充电部 540和第二 电荷充电部 550充入电荷。然后将第一电荷充电部 540和第二电荷充电部 550 变成电浮状态。 为了变成电浮状态， 将为了充入电荷而施加的电压源可以通 过机械开关短路， 或者通过使用探针施加电压并充入电荷之后以物理方式将 其短路。 为了防止在电荷充电部 540、 550已充电的电荷被放电， 优选在其表 面形成防放电层。
然后， 向第一及第二固定电极 530， 540与移动电极 560之间施加电压， 由作用于固定电极 530、 540和移动电极 560之间的静电引力和作用于电荷充 电部 540、 550和移动电极 560之间的静电引力之和使移动电极 560朝固定电 极 520、 530方向进行位移。 通过调节向电荷充电部 540、 550存储的电荷量， 能使移动电极 560仅均对第一及第二固定电极 520， 530施加预先设定的电压 时才被驱动。
表 1中表示有： 根据向第一固定电极 520施加电压与否和向第二固定电 极 530施加电压与否，移动电极 560是否被驱动的情况。向第一固定电极 520 和第二固定电极 530施加电压的情况用" 1 "来表示，不施加电压的情况用 "0" 来表示， 移动电极 560被驱动的情况用 " 1 "来表示， 不驱动的情况用 "0" 来表示， 可以得知： 表 1中的结果与与门 （AND) 的逻辑值相同。 表 1
Figure imgf000014_0001
本说明书中说明的实施例为具有两个输入的与门 （AND)逻辑电路， 但 是这仅作为例示的实施例， 能通过调节固定电极的个数来任意地调整输入的 个数。 并且， 在这里虽然说明了包含两个电荷充电部的结构， 但是其个数并 非限制在两个， 而可以包含任意个电荷充电部。 并且， 在这里虽然说明了电 荷充电部 540、 550和固定电极 520、 530均设置在绝缘基板 510上的结构， 但是只要在施加电压的时与移动电极 560之间能够产生静电引力， 其位置不 受限制。
[开关]
图 9为本发明第四实施例的悬臂式开关示意图。本发明的悬臂式开关 600 包括：绝缘基板 610，在绝缘基板 610上隔离形成的固定电极 620和接触电极 670, 与固定电极 620绝缘的电荷充电部 640， 与固定电极 620和电荷充电部 640隔离形成的移动电极 650， 将移动电极 650支撑于绝缘基板 610上的支撑 部 660， 和凸起部 680。
如果电荷充电部 640被充入电荷， 并且固定电极 620和移动电极 650之 间施加驱动电压， 则移动电极 650朝固定电极 620方向进行位移， 使凸起部 680与接触电极 670接触。 由此， 支撑部 660、 移动电极 650、 凸起部 680和 接触电极 670被导通， 开关处于导通（on)状态。 不施加驱动电压时， 凸起 部 680与接触电极 670隔离， 开关处于断开 （off)状态。 另外， 开关 600的 构成要素的作用与前述的本发明静电致动器的对应的构成要素相同。
以下， 说明本发明的静电开关 600的工作方式。首先， 向电荷充电部 640 充入电荷。 然后， 将电荷充电部 640变成电浮状态。 为了变成电浮状态， 为 了充入电荷而施加的电压可以通过机械开关短路或者通过使用探针施加电压 以充入电荷之后将探针短路。 为了防止已充入的电荷被放电， 在电荷充电部 640表面可以形成防放电层。
然后， 固定电极 620和移动电极 650之间施加临界值以上的驱动电压。 如果施加电压， 则固定电极 620和移动电极 650上被激发出具有相互不同符 号的电荷，并施加驱动电压使得在固定电极 620上激发出与向电荷充电部 640 充入的电荷具有相同符号的电荷。 如果施加临界值以上的电压， 则由固定电 极 620和移动电极 650之间的静电引力和电荷充电部 640和移动电极 650之 间的静电引力之和使移动电极 650的一部分朝固定电极 620方向进行位移。 如果施加临界值以下的电压， 则由支撑部 660或者移动电极 650的回复力， 使移动电极复原到原位置。如果移动电极 650朝固定电极 620方向进行位移， 则形成在移动电极 650末端的凸起部 680与接触电极 670接触， 使开关处于 导通（on)状态。
参照图 9， 固定电极 620形成在绝缘基板 610上， 在其上形成有绝缘层
630, 在其上形成有电荷充电部 640。 只要固定电极 620和电荷充电部 640分 别能够与移动电极 650产生静电引力， 其位置不受任何限制。
图 10为本发明另一实施例的静电开关的示意图，参照图 10，表示有在绝 缘基板 710上固定电极 720和电荷充电部 730隔离形成的结构。如前述说明， 电荷充电部 730和固定电极 720的位置为例示的结构， 并非限制在这种设置 结构上。
另外， 本领域普通技术人员应当理解： 在不改变本发明的技术思想或者 必要特征， 通过其它具体方式能够实现本发明的技术构成。
因此， 应当理解： 上述的实施例在所有方面都是属于例示的， 而并非是 一种限制， 本发明的保护范围与具体的实施方式相比更体现在权利要求书中， 权利要求书的意义及范围并且从其等价概念推导出的所有变化或变形方式均 应包含于本发明的范围内。
产业可利用性
本发明的静电致动器能应用于微机电系统。 具体为， 本发明的静电致动 器可以作为非挥发性机械式存储器、 逻辑电路和开关所利用。

Claims

权 利 要 求 书
1、 一种静电致动器， 其中包括- 固定电极；
与所述固定电极绝缘的电荷充电部；
与所述固定电极和所述电荷充电部隔离形成的移动电极。
2、 根据权利要求 1所述的静电致动器， 其中还包括绝缘基板， 在所述绝 缘基板上形成所述固定电极。
3、 根据权利要求 2所述的静电致动器， 其中还包括： 形成在所述固定电 极上的绝缘层， 所述电荷充电部形成于所述绝缘层上， 所述移动电极形成于 电荷充电部的上部并与所述固定电极和所述电荷充电部相对。
4、 根据权利要求 2所述的静电致动器， 其中所述电荷充电部形成在所述 绝缘基板上并与所述固定电极隔离， 所述移动电极形成于所述固定电极和所 述电荷充电部的上部并与所述固定电极和所述电荷充电部相对。
5、根据权利要求 1所述的静电致动器， 其中还包括形成于所述电荷充电 部的表面的防放电层。
6、根据权利要求 1所述的静电致动器， 其中向所述固定电极和所述移动 电极之间施加驱动电压， 根据所述驱动电压产生的所述固定电极和所述移动 电极之间的第一静电力和所述电荷充电部和所述移动电极之间的第二静电 力， 所述移动电极进行位移。
7、 根据权利要求 6所述的静电致动器， 其中根据所述第一静电力和所述 第二静电力， 所述移动电极的一部分进行位移。
8、根据权利要求 6所述的静电致动器， 其中所述第一静电力和所述第二 静电力为静电引力， 所述移动电极朝所述固定电极方向进行位移。
9、 根据权利要求 1所述的静电致动器， 其中所述电荷充电部预先存储有 电荷。
10、 一种静电致动器的驱动方法， 所述静电致动器包括： 固定电极； 与 所述固定电极绝缘的电荷充电部； 与所述固定电极和所述电荷充电部隔离形 成的移动电极， 其中所述静电致动器的驱动方法包括：
向所述电荷充电部充入电荷的步骤；
在所述固定电极和所述移动电极之间施加驱动电压的步骤。
11、 根据权利要求 10所述的静电致动器的驱动方法， 其中所述充入电荷 的步骤包括：
向所述电荷充电部施加电压的步骤；
电浮所述已充入电荷的电荷充电部的步骤。
12、 根据权利要求 10所述的静电致动器的驱动方法， 其中所述充入电荷 的步骤包括：
利用通过电场的隧穿方法向所述电荷充电部充入电荷的步骤。
13、 一种非挥发性存储器， 其中包括：
固定电极；
与所述固定电极绝缘的电荷充电部；
与所述固定电极和所述电荷充电部隔离形成的移动电极。
14、 一种逻辑电路元件， 其中包括：
固定电极；
与所述固定电极绝缘的电荷充电部；
与所述固定电极和所述电荷充电部隔离形成的移动电极。
15、 一种开关， 其中包括：
相互隔离形成的固定电极和接触电极；
与所述固定电极之间夹有绝缘层而形成的电荷充电部；
在所述固定电极、 电荷充电部和接触电极的上部形成的移动电极。
16、 根据权利要求 15所述的开关， 其中在所述固定电极和所述移动电极 之间施加驱动电压， 根据所述驱动电压产生的所述固定电极与所述移动电极 之间的第一静电力和所述电荷充电部与所述移动电极之间的第二静电力， 所 述移动电极进行位移， 使所述移动电极与所述接触电极接触。
17、 根据权利要求 16所述的开关， 其中还包括形成在所述移动电极的与 所述接触电极接触的部位上的凸起部。
18、 根据权利要求 15所述的开关， 其中还包括： 形成在所述电荷充电部 的表面的防放电层。
19、根据权利要求 15所述的开关，其中所述电荷充电部预先存储有电荷。
20、 根据权利要求 15所述的开关， 其中还包括绝缘基板， 在所述绝缘基 板上形成所述固定电极和接触电极。
21、 根据权利要求 20所述的开关， 其中还包括将所述移动电极支撑于所 述绝缘基板之上的支撑部。
22、 根据权利要求 1所述的静电致动器， 其中所述电荷充电部由导电体、 氧氮氧、 强电介质和驻极体中的任一构成。
PCT/IB2008/050811 2007-06-22 2008-03-06 Electrostatic actuator Ceased WO2009016524A1 (en)

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JP2009525168A JP4864141B2 (ja) 2007-06-22 2008-03-06 静電アクチュエータ
US12/091,555 US8120451B2 (en) 2007-06-22 2008-03-06 Electrostatic actuator

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US20100163376A1 (en) 2010-07-01
CN101542888B (zh) 2011-06-15

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