JP2011109822A - Electrostatic drive type actuator and variable capacity device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic drive type actuator wherein the DC voltage required for hot switching is controlled easily, and the fineness is reduced as compared with the prior art. <P>SOLUTION: The electrostatic drive type actuator includes a substrate 2, a movable plate 6, and lower driving electrodes 5A-5D. The movable plate 6 is connected to the substrate 2 by a support 6C. A sub-movable part 6E and a sub-beam part 6D constitute a cantilever structure which is connected to the main movable part 6B at one end of the sub-beam part 6D. The main movable part 6B and the lower driving electrodes 5C and 5D change the connection state between the lower driving electrodes 5C and 5D by displacement of the main movable part 6B. The sub-movable part 6E and the lower driving electrode 5A deform the movable plate 6 with an electrostatic force which is produced when a DC voltage is applied and is based on the capacitance. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electrostatic drive type actuator using MEMS driven by an electrostatic force, and a variable capacitance device that varies the capacitance by the electrostatic drive type actuator.

  Conventionally, electrostatic drive actuators are sometimes used for switch devices, variable capacitance devices, and the like (see Patent Documents 1 to 3).

FIG. 1 is a diagram for explaining a configuration example of a conventional electrostatic drive actuator adopting a cantilever structure.
The electrostatic drive actuator 101 includes a substrate 102, a support portion 103, and a movable plate 104. One end of the movable plate 104 is fixed to the substrate 102 by the support portion 103 to form a cantilever structure. The movable plate 104 and the substrate 102 are formed with first electrode pairs 105A and 105B and second electrode pairs 106A and 106B that are opposed to each other with a gap therebetween. The first electrode pairs 105A and 105B function as a drive capacitance forming portion of the electrostatic drive type actuator 101, and a capacitance is generated when a DC voltage is applied, and the movable plate 104 is driven by an electrostatic force. Deform. The second electrode pairs 106 </ b> A and 106 </ b> B function as signal variable portions of the electrostatic drive actuator 101. The electrode 106A is a signal line having an electrode gap provided on the substrate 102. The electrode 106B faces the electrode gap, and the movable plate 104 is deformed to connect the electrode 106B between the electrodes 106A.

FIG. 2 is a diagram for explaining a configuration example of a conventional electrostatic drive actuator adopting a double-supported beam structure.
The electrostatic drive type actuator 201 includes support portions 203A and 203B, drive capacitance forming portions 204A and 204B, and a signal variable portion 205. The drive capacitance forming units 204A and 204B are disposed between the support units 203A and 203B and the signal variable unit 205.

FIG. 3 is a diagram for explaining a configuration example of a conventional electrostatic drive actuator that employs a multi-link structure in which a double-supported beam structure is combined.
The electrostatic drive actuator 301 includes first support portions 303A and 303B, second support portions 304A and 304B, drive capacitance forming portions 305A and 305B, and a signal variable portion 306. The signal variable unit 306 is disposed in the central portion of the first double-supported beam structure, both ends of which are supported by the first support units 303A and 303B. The drive capacity forming portion 305A is arranged in a second both-end supported beam structure in which both ends are supported by the central portion of the first both-end supported beam structure and the second support portion 304A. The driving capacity forming portion 305B is arranged in a third both-end supported beam structure in which both ends are supported by the central portion of the first both-end supported beam structure and the second support portion 304B.

Japanese Patent Laid-Open No. 09-17300 Japanese Patent No. 3538109 JP 2008-278634 A

  The electrostatic drive type actuators described in Patent Documents 1 and 2 use a high voltage RF signal between the electrodes of the signal variable unit during switching (hot switching) with a high voltage RF signal on the signal line. An electrostatic force is generated. As a result, the beam structure cannot be properly deformed by the DC voltage of the drive capacitor forming portion, which may hinder hot switching. If the spring constant of the beam structure is high, deformation based on a high-voltage RF signal can be suppressed, but at the same time, deformation of the beam structure based on a DC voltage is also suppressed. For this reason, the DC voltage required for hot switching increases, and a booster circuit or the like is required, resulting in a new problem that complicates the circuit configuration.

In the electrostatic drive actuator described in Patent Document 3, the spring constant of the first cantilever beam structure is increased, and the spring constant of the second and third cantilever beam structures is increased. Make it smaller than a constant. In this structure, the second and third cantilever beam structures are easily deformed, and a relatively large capacitance can be generated with a small DC voltage. That is, the necessary electrostatic force can be generated with a small DC voltage, and switching can be performed while suppressing the DC voltage even if the spring constant of the first doubly supported beam structure is increased.
However, in order to reduce the spring constant of the second and third both-end supported beam structures, the distance from the support portion to the drive capacity forming portion in the second and third both-end supported beam structures can be increased. It is necessary to narrow the width. For this reason, the second and third cantilever beam structures are miniaturized, and the performance and size may be restricted due to the limit of the fineness due to the manufacturing method.

  Accordingly, an object of the present invention is to provide an electrostatic drive actuator that can easily suppress a DC voltage required for hot switching and can reduce the fineness as compared with the prior art, and a variable capacitance device using the electrostatic drive actuator. It is to provide.

The electrostatic drive actuator according to the present invention includes a substrate, a main beam portion, a sub beam portion, a signal variable portion, and a drive capacitance forming portion. The main beam is connected to the substrate at the connection end. The secondary beam portion has a cantilever structure and is connected to the movable portion of the main beam portion at the connection end. The signal variable part is configured by a main beam part and a substrate, and changes a control target signal by displacement of a movable part of the main beam part. The drive capacity forming section is configured on the sub-beam section and the substrate, and deforms the main beam section and the sub-beam section with an electrostatic force based on a capacitance generated when a DC voltage is applied.
In this configuration, since the secondary beam portion has a cantilever structure, the spring constant and the exclusive area of the secondary beam portion can be reduced as compared with the case where the secondary beam portion is configured as a double-supported beam structure. Therefore, the spring constant of the sub-beam portion can be reduced without increasing the structural fineness as in the conventional case where the sub-beam portion is constituted by a double-supported beam structure. This makes it easier to suppress the DC voltage required for hot switching by making the spring constant of the main beam portion larger than the spring constant of the sub beam portion.

It is preferable that the sub-beam portion of the present invention has a configuration in which a plurality of portions whose dimensions in the direction parallel to the substrate are partially small in the cross section perpendicular to the main axis direction are arranged in the main axis direction.
If the width dimension of the secondary beam part is not constant but discontinuous, the area of the secondary beam part is locally expanded to facilitate securing the capacitance, but the spring constant is not uniform and the DC voltage is controlled. The degree of deformation of the beam due to is irregular. Therefore, it becomes difficult to control the control target signal. Therefore, a configuration is adopted in which a portion having a wide width and a portion having a narrow width of the secondary beam portion are alternately arranged in the axial direction, and the spring constant in the secondary beam portion is equivalently uniform. As a result, the degree of deformation of the beam portion can be easily controlled, and the control target signal can be stably controlled.

The main beam portion and the sub beam portion of the present invention may be made of an integral conductive material, and an element for signal cut may be connected to the drive capacitor forming portion. In addition, the main beam portion and the sub beam portion of the present invention may be made of an insulating material, and an electrode serving as a drive capacitance forming portion or a signal variable portion may be formed on the surface.
If the main beam portion and the sub-beam portion are formed of an integral conductive material, it is not necessary to provide an electrode that becomes a drive capacitance forming portion or a signal variable portion. Then, it is not necessary to make the beam part a different material bonding structure, and it is possible to suppress the warpage based on the difference in internal stress and the change in capacitance based on the difference in linear expansion, and to obtain a highly accurate variable capacity with small characteristic variation. Can do. If the main beam portion and the sub beam portion are made of an insulating material, it is not necessary to connect the signal cut element to the drive capacitance forming portion.

The drive capacitor forming portion of the present invention is opposed to the first substrate side electrode portion and the second substrate side electrode portion, and the first substrate side electrode portion and the second substrate side electrode portion facing the sub beam portion. The beam side electrode part to be provided may be configured such that a DC voltage is applied between the first substrate side electrode part and the second substrate side electrode part. The drive capacitor forming portion of the present invention includes a substrate-side electrode portion facing the sub-beam portion and a beam-side electrode portion facing the substrate-side electrode portion, and includes a substrate-side electrode portion and a beam-side electrode portion. A configuration in which a DC voltage is applied between them may be used.
A structure in which a DC voltage is applied between the beam-side electrode part and the substrate-side electrode part (hereinafter referred to as an MIM structure) is a DC between two substrate-side electrode parts coupled via the beam-side electrode part. Compared with a structure to which a voltage is applied (hereinafter referred to as a MIMIM structure), the capacitance and electrostatic force are quadrupled as shown in Equation 1 and Equation 2. Therefore, the DC voltage for obtaining the same electrostatic force can be suppressed. On the other hand, the MIMIM structure does not require an electrical contact for applying a DC voltage to the beam-side electrode portion, and can be easily configured and easily downsized.

  The main beam portion of the present invention may have a double-supported beam structure or a cantilever structure. The cantilever beam structure has a higher spring constant than the cantilever beam structure, and the capacitance change stability can be improved by making the main beam part and the substrate parallel to each other at the signal variable part. On the other hand, the size of the cantilever beam structure can be smaller than that of the double-sided beam structure.

The drive capacitor forming portion of the present invention preferably has a larger electrode area facing area than the signal variable portion.
The electrostatic force acting on the parallel plate capacitor is proportional to the electrode portion facing area. Therefore, it is easy to realize proper operation by weakening the electrostatic force generated in the signal variable unit during hot switching by configuring the electrode facing area in the drive capacitance forming unit to be larger than that of the signal variable unit. become.

  The signal variable portion according to the present invention includes a first substrate side electrode portion and a second substrate side electrode portion facing the main beam portion, and a gap between the first substrate side electrode portion and the second substrate side electrode portion. A configuration may be adopted in which an electric signal is propagated between a first substrate side electrode portion and a second substrate side electrode portion which are provided with opposing beam side electrode portions and are conducted through the beam side electrode portion.

  The signal variable portion of the present invention includes a first substrate side electrode portion and a second substrate side electrode portion facing the main beam portion, and a beam facing the first substrate side electrode portion and the second substrate side electrode portion. A configuration in which an RF signal propagates between a first substrate side electrode portion and a second substrate side electrode portion that are provided with a side electrode portion and are coupled via a beam side electrode portion may be possible.

  The variable capacitance device according to the present invention preferably includes a plurality of the above-described electrostatic drive actuators, and is configured to connect each first substrate-side electrode unit and each second substrate-side electrode unit. It is.

  According to this invention, since the secondary beam portion has a cantilever structure, the spring constant and the exclusive area of the secondary beam portion are reduced as compared with the case where the secondary beam portion is configured as a double-supported beam structure. Therefore, the spring constant of the sub-beam portion can be reduced without increasing the structural fineness as in the conventional case where the sub-beam portion is constituted by a double-supported beam structure. This makes it easier to suppress the DC voltage required for hot switching by making the spring constant of the main beam portion larger than the spring constant of the sub beam portion.

It is a figure explaining the 1st structural example of the conventional electrostatic drive type actuator. It is a figure explaining the 2nd structural example of the conventional electrostatic drive type actuator. It is a figure explaining the 3rd structural example of the conventional electrostatic drive type actuator. It is a figure explaining the structural example of the electrostatic drive type actuator which concerns on the 1st Embodiment of this invention. It is a figure explaining an example of the manufacturing method of an electrostatic drive type actuator. It is a figure explaining the structural example of the electrostatic drive type actuator which concerns on the 2nd Embodiment of this invention. It is a figure explaining the structural example of the electrostatic drive type actuator which concerns on the 3rd Embodiment of this invention. It is a figure explaining the structural example of the electrostatic drive type actuator which concerns on the 4th Embodiment of this invention. It is a figure explaining the structural example of the electrostatic drive type actuator which concerns on the 5th Embodiment of this invention. It is a figure explaining the structural example of the electrostatic drive type actuator which concerns on the 6th Embodiment of this invention. It is a figure explaining the structural example of the electrostatic drive type actuator which concerns on the 6th Embodiment of this invention. It is a figure explaining the structural example of the variable capacitance apparatus which concerns on the 7th Embodiment of this invention.

  A configuration example of the electrostatic drive actuator according to the first embodiment of the present invention will be described.

  FIG. 4A is a plan view of the electrostatic drive actuator 1 with the upper cover removed. FIG. 4B is a side sectional view of the electrostatic drive actuator 1 when the switch is OFF. FIG. 4C is a side sectional view of the electrostatic drive actuator 1 when the switch is ON.

  The electrostatic drive actuator 1 includes a substrate 2, an upper cover 3, a side cover 4, lower drive electrodes 5 </ b> A to 5 </ b> D, a movable plate 6, and a dielectric film 7. The substrate 2, the upper surface cover 3, and the side surface cover 4 serve as exterior materials. The substrate 2 and the top cover 3 are made of a glass substrate, and the side cover 4 and the movable plate 6 are made of a low resistance Si substrate having a resistivity of 0.0026 Ωcm.

  The substrate 2 is formed with through holes 8, bump electrodes 9A, and solder bumps 9B. The bump electrode 9A is formed on the bottom surface of the substrate 2. The solder bump 9B is joined to the bump electrode 9A. The through hole 8 is formed through the substrate 2 and connects the lower drive electrodes 5A to 5D and the bump electrode 9A.

  The movable plate 6 is made of a flat plate-like conductive material having an opening and a uniform thickness, and includes two main beam-like portions 6A, a main movable portion 6B, a support portion 6C, and two sub-beam-like portions 6D. A sub movable part 6E is provided. The support portion 6 </ b> C is formed in a convex shape at the left end portion of the movable plate 6 in the figure and is joined to the substrate 2. The main movable portion 6B is formed in a rectangular shape at the right end portion of the movable plate 6 in the figure. The two main beam-like portions 6A are line-like regions that connect between the support portion 6C and the main movable portion 6B. The main beam-shaped portion 6A, the main movable portion 6B, and the support portion 6C constitute the main beam portion of the present invention, and the main beam-shaped portion 6A and the main movable portion 6B are supported by the support portion 6C in a state where they are separated from the substrate 2. And constitute a cantilever structure.

  The sub movable portion 6 </ b> E is provided in a rectangular shape in the opening of the movable plate 6. The two auxiliary beam-like portions 6D are line-like regions that connect between the auxiliary movable portion 6E and the main movable portion 6B. The sub movable part 6E and the sub beam-like part 6D constitute a sub beam part of the present invention, and are supported by the main movable part 6B in a state of being separated from the substrate 2 to form a cantilever structure. A flange portion that partially protrudes from the bottom surface is provided on the bottom surface of the sub movable portion 6E in order to prevent the sub movable portion 6E from coming into contact with the lower drive electrode 5A. Thus, by making the sub-beam-like portion 6D and the sub-movable portion 6E have a cantilever structure, the spring constant and the exclusive area can be reduced as compared with the case of the double-support beam structure. Further, since the auxiliary movable portion 6E is provided separately from the auxiliary beam-like portion 6D, it becomes easy to secure the capacitance by locally expanding the area of the auxiliary beam portion.

  The lower drive electrode 5B is joined to the support portion 6C of the movable plate 6 at a convex portion formed near the center left side of the upper surface of the substrate, and is connected to the ground via the through hole 8. The lower drive electrode 5A is a rectangular portion formed near the center of the upper surface of the substrate, faces the sub movable portion 6E of the movable plate 6, and is connected to the reference DC voltage via the through hole 8. The lower drive electrode 5A and the sub movable portion 6E form a capacitance by the reference DC voltage and the ground, and constitute a drive capacitance forming portion of the present invention that promotes deformation of the entire movable plate 6 by electrostatic force. The structure of the driving capacitance forming portion is a so-called MIM structure including a lower drive electrode 5A, a sub movable portion 6E, and a gap formed by the lower drive electrode 5A and the sub movable portion 6E. The lower drive electrode 5A corresponds to the substrate side electrode portion of the present invention, the sub movable portion 6E facing the lower drive electrode 5A corresponds to the beam side electrode portion of the present invention, and the lower drive electrode 5A and the sub drive electrode to which a voltage is applied. The movable part 6E faces each other. This MIM structure has a larger electrostatic force per area than the MIMIM structure described later, and is advantageous in reducing the electrode area.

  The lower drive electrode 5C is opposed to the main movable portion 6B of the movable plate 6 at a line portion formed near the center right side of the upper surface of the substrate, and is connected to the high frequency signal input terminal through the through hole 8. The lower drive electrode 5D is opposed to the main movable portion 6B of the movable plate 6 at a line portion parallel to the line portion of the lower drive electrode 5C, and is connected to the high frequency signal output terminal through the through hole 8. The dielectric film 7 covers the line portion of the lower drive electrode 5C and the lower drive electrode 5D and faces the main movable portion 6B of the movable plate 6. The high frequency signal is the control target signal of the present invention, and the lower drive electrodes 5C and 5D, the dielectric film 7, and the main movable part 6B are connected to the lower drive electrode 5C depending on the contact state between the main movable part 6B and the dielectric film 7. The signal variable portion of the present invention is configured to change the coupling state with the lower drive electrode 5D. The signal variable portion has a so-called MIMIM structure including a lower drive electrode 5C, a dielectric film 7, a main movable portion 6B, a dielectric film 7, and a lower drive electrode 5D. The lower drive electrodes 5C and 5D correspond to the first and second substrate side electrode portions of the present invention, the main movable portion 6B facing the lower drive electrode 5A corresponds to the beam side electrode portion of the present invention, and a signal is applied. The lower drive electrodes 5 </ b> C and 5 </ b> D are opposed to the movable plate 6 and coupled via the movable plate 6. The MIMIM structure has a smaller electrostatic force per area than the MIM structure, and is advantageous in suppressing deformation during hot switching.

  When the switch shown in FIG. 4B is OFF, the reference DC voltage is not applied to the lower drive electrode 5A, and no capacitance is formed between the lower drive electrode 5A and the sub movable portion 6E. Therefore, no electrostatic force acts on the movable plate 6 and no deformation occurs, and the main movable portion 6B of the movable plate 6 is in a state of being separated from the dielectric film 7. Thereby, the electrical connection between the lower drive electrode 5C and the lower drive electrode 5D is cut off.

  When the switch shown in FIG. 4C is ON, a reference DC voltage is applied to the lower drive electrode 5A, and a capacitance is formed between the lower drive electrode 5A and the sub movable portion 6E. For this reason, electrostatic force acts on the movable plate 6 to cause deformation, and the main movable portion 6B of the movable plate 6 comes into contact with the dielectric film 7. As a result, the lower drive electrode 5C and the lower drive electrode 5D are coupled to each other via the capacitance generated between the main movable portion 6B of the movable plate 6.

  At the time of hot switching, static electricity having a certain size between the lower drive electrode 5C and the main movable portion 6B and between the lower drive electrode 5D and the main movable portion 6B even when the reference DC voltage is not applied to the lower drive electrode 5A. There is a possibility that a capacitance is generated and the movable plate 6 is deformed by the electrostatic force thereby to come into contact with the dielectric film 7. Therefore, here, the spring constant of the main beam-like portion 6A is made larger than the spring constant of the sub-beam-like portion 6D. Thereby, the bending of the movable plate 6 due to the electrostatic force generated in the signal variable portion at the time of hot switching is suppressed, and the main movable portion 6B is prevented from contacting the dielectric film 7.

  Here, the electrostatic force acting on the movable plate 6 will be described. The movable plate 6 and the lower drive electrodes 5A, 5C, 5D function as a parallel plate capacitor. The electrostatic force F acting on the parallel plate capacitor is expressed by Equation 1, and is proportional to the square of the opposed area A and the applied voltage V of the parallel plate capacitor and inversely proportional to the square of the opposed distance z.

  Therefore, the smaller the facing distance z in the drive capacitance forming portion composed of the sub movable portion 6E and the lower drive electrode 5A is advantageous in securing the electrostatic force F. In other words, when the same electrostatic force F is obtained, the facing area A and the applied voltage V can be reduced when the facing distance z is smaller. That is, even if the spring constant of the main beam-like portion 6A is large, if the spring constant of the sub-beam-like portion 6D is small, the amount of bending of the sub-beam-like portion 6D tends to increase, and the sub-movable portion 6E and the lower drive electrode The facing distance z to 5A is reduced, and the required electrostatic force F can be obtained at the drive capacitor forming portion even at a low reference DC voltage.

  In addition, the opposing area in the drive capacitance forming part composed of the sub movable part 6E and the lower drive electrode 5A is larger than the opposing area in the signal variable part composed of the main movable part 6B and the lower drive electrodes 5C and 5D. Is preferred. This makes it easier to realize a more appropriate operation by weakening the electrostatic force generated in the signal variable unit at the time of hot switching than the electrostatic force generated in the drive capacitance forming unit.

  Next, a method for manufacturing the electrostatic drive actuator 1 will be described with reference to FIG. Normally, a plurality of elements are formed from a very large mother board. However, here, for the sake of simplicity of explanation, it is assumed that one element is formed from the mother board.

  First, a glass substrate to be the substrate 2 is prepared (S1).

  Next, a non-through opening is formed by sandblasting or the like at a position where the through hole 8 of the substrate 2 is to be formed, and the entire upper surface of the substrate 2 including the inside of the opening is covered with copper by a filling plating method or the like (S2).

  Next, the copper coating is removed from the upper surface of the substrate 2 by grinding and polishing. Thereby, the copper remaining in the opening of the substrate 2 forms the through hole 8 (S3).

  Next, a metal film such as Au / Pt / NiCr and Cr / Au / Pt / Cr is formed on the upper surface of the substrate 2 to a thickness of 0.2 μm, and lower drive electrodes 5A to 5D having a predetermined pattern are formed by a lift-off method or the like. (S4). In order to reduce the resistance of the lower drive electrodes 5C and 5D, the lead wiring portion of the lower drive electrode may be made about 0.6 μm thick with Cr / Au / Pt · Cr.

Next, a dielectric film made of Ta ₂ O ₅ (ε = 22 to 28) or the like is formed by sputtering to a thickness of 0.2 μm, and a dielectric film 7 having a predetermined pattern is formed by the RIE method or the like (S5).

  Next, a low-resistance Si substrate 4A provided with a recess having a predetermined shape is prepared by RIE or the like, and anodic bonded to the substrate 2 at 400.degree.

  Next, the low-resistance Si substrate is booked to a thickness of 30 μm by TMAH / grinding / polishing method or the like, a predetermined pattern is formed by RIE method or the like, and the side cover 4 and the movable plate 6 are provided (S7).

  Next, a glass substrate provided with a concave portion having a predetermined shape is prepared by sandblasting or the like, and thermally bonded at 400 ° C. to the upper surface of the side cover 4 as the upper surface cover 3. At this time, the internal space surrounded by the top cover 3, the side cover 4, and the substrate 2 is sealed under reduced pressure (S8). Note that the depth of the recess in the upper surface cover 3 is determined in consideration of the thickness of each substrate, the bonding method, and the like, and may be about 100 μm, for example.

  Next, the bottom surface of the substrate 2 is ground to a substrate thickness of 0.1 mm by grinding / polishing or the like, and the through hole 8 is exposed from the bottom surface (S9).

  Next, a solder resist made of polyimide or the like is formed, and a bump electrode 9A that covers the through hole is formed by electroplating or the like. Then, the solder bump 9B is joined to the bump electrode 9A by printing or the like (S10).

  The electrostatic drive actuator 1 of the present invention is manufactured through the above steps. When the plurality of electrostatic drive actuators 1 are formed on a large mother board and then separated into individual pieces, the mother board is half-cut by dicing and attached to a tape material, and then diced again. It is good to divide an element into pieces.

  Next, a configuration example of the electrostatic drive actuator according to the second embodiment of the present invention will be described.

  The electrostatic drive actuator 11 of the present embodiment is different from the above-mentioned electrostatic drive actuator 1 in the shape of the lower drive electrode and the shape of the movable part, and in particular, the main beam part constituting the movable part has a double-supported beam structure. This is different in that two auxiliary beam portions are provided. FIG. 6A is a plan view of the electrostatic drive actuator 11 with the upper cover removed. FIG. 6B is a side sectional view of the electrostatic drive actuator 11 when the switch is OFF. FIG. 6C is a side sectional view of the electrostatic drive actuator 11 when the switch is ON.

  The electrostatic drive actuator 11 includes a substrate 12, an upper cover 13, a side cover 14, lower drive electrodes 15 </ b> A to 15 </ b> D, a movable plate 16, and a dielectric film 17.

  The movable plate 16 is made of a rectangular flat plate-shaped conductive material provided with two openings, 2 × 2 sets of main beam-shaped portions 16A, a main movable portion 16B, two support portions 16C, and 2 × 2 sets. The auxiliary beam-shaped part 16D and the two auxiliary movable parts 16E are provided. The two support portions 16 </ b> C are formed in a rectangular shape at both ends of the movable plate 16 and are joined to the substrate 12. The main movable portion 16B is formed in a rectangular shape at the center of the movable plate 16 in the figure. The two main beam-like portions 16A of each set are line-like regions that connect between the support portion 16C and the main movable portion 16B. The main beam portion 16A, the main movable portion 16B, and the support portion 16C constitute the main beam portion of the present invention, and the main beam portion 16A and the main movable portion 16B are supported by the support portion 16C in a state where they are separated from the substrate 12. And constitutes a doubly supported beam structure.

  The two sub movable parts 16E are provided in a rectangular shape in the two openings of the movable plate 16. The two sub beam-like portions 16D of each group are line-like regions that connect between the sub movable portion 16E and the main movable portion 16B. The sub movable portion 16E and the sub beam-like portion 16D constitute a sub beam portion of the present invention, and are supported by the main movable portion 16B in a state of being separated from the substrate 12, thereby constituting a cantilever structure.

  The lower drive electrode 15B is joined to a support portion 16C provided at the right end of the movable plate 16 in the figure and connected to the ground. The lower drive electrode 15A is opposed to the two sub movable portions 16E of the movable plate 16 at two rectangular portions, and is connected to a reference DC voltage. The lower drive electrode 15A and the sub movable portion 16E constitute a drive capacitance forming portion of the present invention. The lower drive electrode 15C faces the main movable portion 16B of the movable plate 16 at the line portion, and is connected to the high frequency signal input terminal. The lower drive electrode 15D faces the main movable portion 16B of the movable plate 16 at the line portion, and is connected to the high frequency signal output terminal. The dielectric film 17 covers the line portion between the lower drive electrode 15C and the lower drive electrode 15D, and faces the main movable portion 16B of the movable plate 16. These lower drive electrodes 15C and 15D, the dielectric film 17, and the main movable portion 16B constitute a signal variable portion of the present invention.

  In the electrostatic drive type actuator 11, the main movable portion 16 </ b> B is supported by a doubly supported beam structure and is parallel to the substrate 12. Therefore, variation in capacitance in the signal variable unit is suppressed.

  Next, a configuration example of an electrostatic drive actuator according to the third embodiment of the present invention will be described.

  FIG. 7A is a plan view of the electrostatic drive actuator 21 according to this embodiment with the upper cover and side covers removed. The electrostatic drive actuator 21 includes a movable plate 26 having a shape different from that of the electrostatic drive actuator 1 described above.

  The movable plate 26 has a uniform thickness dimension in the direction Z perpendicular to the substrate 22, and includes a main beam portion 26A, a main movable portion 26B, a support portion 26C, and a sub beam portion 26D. The sub beam portion 26D includes a plurality of slits 26E arranged in the main axis direction X of the beam.

  In the electrostatic drive actuator 21, the dimension (width dimension) of the sub-beam portion 26D along the direction Y perpendicular to the directions X and Z is reduced at the portion where the slit 26E is provided. Therefore, by arranging the plurality of slits 26E in the main axis direction X, the sub beam portion is more gently deformed than the above-described electrostatic drive actuator 1, and the portion of the sub beam portion parallel to the substrate is gradually enlarged when the switch is turned on. It becomes easier to stabilize the change in capacitance.

  FIG. 7B is a plan view showing a configuration example in which the main beam portion has a double-supported beam structure in the configuration of the electrostatic drive actuator according to the present embodiment. In this electrostatic drive type actuator 31, the secondary beam portion is deformed more gently than the electrostatic drive type actuator 11 described above, and when the switch is turned on, the portion parallel to the substrate of the secondary beam portion gradually expands. It becomes easy to stabilize the change in capacitance.

  Next, a configuration example of an electrostatic drive actuator according to the fourth embodiment of the present invention will be described.

  FIG. 8 is a plan view of the electrostatic drive actuator 41 according to this embodiment with the upper cover and the side cover removed. The electrostatic drive actuator 41 includes lower drive electrodes 45A and 45B having a shape different from that of the electrostatic drive actuator 21 described above.

  The lower drive electrode 45B is a rectangular portion formed near the center right side of the upper surface of the substrate, faces the sub-beam portion of the movable plate, and is connected to the ground. The lower drive electrode 45A is a rectangular portion formed near the center left side of the upper surface of the substrate, faces the sub-beam portion of the movable plate, and is connected to a reference DC voltage. The lower drive electrode 45A and the lower drive electrode 45B constitute a drive capacitance forming portion of the present invention. The structure of the driving capacitor forming portion is a so-called MIMIM structure. The lower drive electrodes 45A and 25B correspond to the first and second substrate side electrode portions of the present invention, the auxiliary movable portion 6E facing the lower drive electrodes 45A and 45B corresponds to the beam side electrode portion of the present invention, and the voltage Are applied to the lower drive electrodes 45A and 45B facing the movable plate. Although this configuration has a smaller electrostatic force per area than the MIM structure, it is not necessary to apply a voltage to the movable plate, which is advantageous for downsizing the movable plate.

  Next, a configuration example of an electrostatic drive actuator according to the fifth embodiment of the present invention will be described.

  FIG. 9A is a plan view of the electrostatic drive actuator 51 according to this embodiment with the upper cover and side covers removed. The electrostatic drive actuator 51 includes a lower drive electrode 55A having a shape different from that of the electrostatic drive actuator 41 described above.

  The lower drive electrode 55A is a rectangular portion formed near the central left side of the upper surface of the substrate and faces the sub-beam portion of the movable plate. The lower drive electrode 55A is a main beam portion of the movable plate at the line-shaped portion 55A1 formed near the right side of the upper surface of the substrate. And is connected to a reference DC voltage. With this configuration, a relatively large electrostatic force can be obtained, and the reference DC voltage can be further suppressed. Since the lower drive electrode 55A needs to partially intersect the lower drive electrode 55C, a part of the substrate 52 is covered with an insulating bridge layer 53 so that it is between the lower drive electrode 55A and the lower drive electrode 55C. Ensure insulation.

  FIG. 9B is a plan view showing a configuration example in which the drive capacitor forming portion has a MIM structure in the configuration of the electrostatic drive actuator according to the present embodiment. Similarly to the electrostatic drive actuator 51 described above, this electrostatic drive actuator 61 has the line-shaped portion 65A1 formed near the right side of the upper surface of the substrate, so that a relatively large electrostatic force can be obtained and the reference DC voltage can be obtained. Can be further suppressed.

  Next, a configuration example of the electrostatic drive actuator according to the sixth embodiment of the present invention will be described.

  FIG. 10 is a side sectional view of the electrostatic drive actuator 71 according to the present embodiment. The electrostatic drive actuator 71 is different from the electrostatic drive actuator 1 described above in that the upper drive electrodes 76A and 76B are provided separately from the movable plate 76.

  If the movable plate 76 is a low-resistance Si substrate like the electrostatic drive type actuator 1, by providing the upper drive electrodes 76A and 76B, the resistance component of the variable capacitor formed by the signal variable portion is reduced, and the Q value is reduced. Can be improved. Further, if the movable plate 76 is an insulating substrate such as a high-resistance Si substrate, the RF signal or the like does not leak from the signal variable section, and there is no need to provide a resistance element for signal cutoff described later. In this case, it is necessary to use an electrode on the Si substrate side, and the material is preferably W (tungsten) or Mo (molybdenum), which does not roughen the surface due to the thermal load during anodic bonding.

  Next, a configuration example of the electrostatic drive actuator according to the seventh embodiment of the present invention will be described.

  FIG. 11 is a side sectional view of the electrostatic drive actuator 81 according to the present embodiment. The electrostatic drive type actuator 81 is configured without providing a dielectric layer in the signal variable portion, and switching is performed by contact between the upper drive electrode 86B and the lower drive electrode 85C, and the upper drive electrode 86B and the lower drive electrode 85D. This is different from the electrostatic drive actuator 71 described above. Even with such a configuration, the present invention can be suitably implemented. The lower drive electrodes 85C and 85D correspond to the first and second substrate side electrode portions of the present invention, and the upper drive electrode 86B faces the gap between the first and second substrate side electrode portions of the present invention. An electric signal, which is a control target signal, propagates between the lower drive electrodes 85C and 85D that correspond to the beam-side electrode portion and are conducted through the upper drive electrode 86B.

  Next, a configuration example of a variable capacitance device using an electrostatic drive actuator according to an eighth embodiment of the present invention will be described.

  FIG. 12A is a diagram illustrating the variable capacitance device 91 according to the present embodiment. The variable capacitance device 91 includes a plurality of electrostatic drive actuators 1 on a single substrate, and each signal variable unit is connected in parallel to turn on a reference DC voltage applied to each electrostatic drive actuator 1. The capacitance is variable by rearranging / OFF. Note that here, the capacitances unique to each of the electrostatic drive actuators 1 are varied to widen the range of capacitance values that can be varied by the variable capacitance device 91. In addition, a resistance element for signal interruption is inserted on the reference DC voltage line of each electrostatic drive actuator 1 in order to prevent leakage of the RF signal.

  Such a variable capacitance device 91 is incorporated in a VMD (Variable Matching Device) device. FIG. 12B is a diagram for explaining a configuration example of the VMD device 95. The VMD device 95 is used for impedance matching on a signal line between the first external load 96A and the second external load 96B. The VMD device 95 includes an inductor 97 connected in series to a signal line, and a variable capacitance device 91 connected between both ends of the inductor 97 and the ground. By using the variable capacitance device 91 in this way, the VMD device 95 can be reduced in size.

DESCRIPTION OF SYMBOLS 1,11,21,31,41,51,61,71,81 ... Electrostatic drive type actuator 2,12,22,52 ... Substrate 3,13 ... Top cover 4,14 ... Side cover 4A ... Low resistance Si substrate 5A to 5D, 15A to 15D, 45A, 45B, 55A, 55C, 65A, 85C, 85D ... Lower drive electrodes 6, 16, 26, 56, 66 ... Movable plates 6A, 16A, 26A ... Main beam-like portions 6B, 16B , 26B ... main movable part 6C, 16C, 26C ... support part 6D, 16D ... sub beam-like part 6E, 16E ... sub movable part 7, 17 ... dielectric film 8 ... through hole 9A ... bump electrode 9B ... solder bump 26D ... sub Beam portion 26E ... Slit 53 ... Bridge layer 76 ... Movable plate 76A, 76B ... Upper drive electrode 86B ... Upper drive electrode 91 ... Variable capacitance device 95 ... VMD device 96A, 96B ... External load

Claims (12)

A substrate,
A main beam portion connected to the substrate at a connection end;
A sub-beam portion of a cantilever structure connected to a movable part of the main beam portion at a connection end;
A signal variable unit configured to change a control target signal by displacement of a movable part of the main beam part, configured on the main beam part and the substrate,
A driving capacity forming portion configured to deform the sub beam portion and the main beam portion with an electrostatic force based on an electrostatic capacitance generated when a DC voltage is applied, configured on the sub beam portion and the substrate,
An electrostatic drive type actuator comprising:   The sub-beam portion has a plurality of portions arranged in the principal axis direction in a section perpendicular to the principal axis direction, the thickness dimension in the direction perpendicular to the substrate is constant in the axial direction, and the width dimension in the direction parallel to the substrate is partially small The electrostatic drive actuator according to claim 1, wherein the actuator is configured.   The electrostatic drive actuator according to claim 1, wherein the main beam portion and the sub beam portion are made of an integral conductive material, and an element for signal cut is connected to the drive capacitance forming portion.   The electrostatic drive actuator according to claim 1, wherein the main beam portion and the sub beam portion are made of an insulating material, and electrodes serving as the drive capacitance forming portion or the signal variable portion are formed on a surface. .   The drive capacitance forming portion is formed on the first substrate side electrode portion and the second substrate side electrode portion, the first substrate side electrode portion, and the second substrate side electrode portion facing the sub beam portion. 5. The structure according to claim 1, further comprising a beam-side electrode portion facing each other, wherein a DC voltage is applied between the first substrate-side electrode portion and the second substrate-side electrode portion. Electrostatic drive type actuator.   The drive capacitance forming portion includes a substrate side electrode portion facing the sub-beam portion and a beam side electrode portion facing the substrate side electrode portion, and the substrate side electrode portion and the beam side electrode portion The electrostatic drive actuator according to claim 1, wherein a DC voltage is applied between them.   The electrostatic drive actuator according to claim 1, wherein the main beam portion has a double-supported beam structure.   The electrostatic drive actuator according to claim 1, wherein the main beam portion has a cantilever structure.   The electrostatic drive actuator according to claim 1, wherein the driving capacitance forming unit has a larger electrode facing area than the signal variable unit.   The signal variable portion includes a first substrate side electrode portion and a second substrate side electrode portion facing the main beam portion, and a gap between the first substrate side electrode portion and the second substrate side electrode portion. And an electric signal propagates between the first substrate side electrode portion and the second substrate side electrode portion that are conducted through the beam side electrode portion. The electrostatic drive actuator according to claim 1.   The signal variable portion faces the first substrate side electrode portion and the second substrate side electrode portion facing the main beam portion, and faces the first substrate side electrode portion and the second substrate side electrode portion. An RF signal propagates between the first substrate side electrode unit and the second substrate side electrode unit coupled to each other through the beam side electrode unit. The electrostatic drive actuator according to any one of 1 to 9. A plurality of the electrostatic drive actuators according to claim 11,
A variable capacitance device having a configuration in which a first substrate side electrode portion of each electrostatic drive actuator is connected and a second substrate side electrode portion of each electrostatic drive actuator is connected.

Images