WO2011158708A1 - Variable capacitance device - Google Patents

Variable capacitance device Download PDF

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Publication number
WO2011158708A1
WO2011158708A1 PCT/JP2011/063101 JP2011063101W WO2011158708A1 WO 2011158708 A1 WO2011158708 A1 WO 2011158708A1 JP 2011063101 W JP2011063101 W JP 2011063101W WO 2011158708 A1 WO2011158708 A1 WO 2011158708A1
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WO
WIPO (PCT)
Prior art keywords
movable beam
drive
line
support plate
capacitance
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PCT/JP2011/063101
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French (fr)
Japanese (ja)
Inventor
山田宏
柴原輝久
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株式会社村田製作所
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Publication of WO2011158708A1 publication Critical patent/WO2011158708A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G5/00—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture
    • H01G5/16—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture using variation of distance between electrodes
    • H01G5/18—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture using variation of distance between electrodes due to change in inclination, e.g. by flexing, by spiral wrapping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • B81B3/0064—Constitution or structural means for improving or controlling the physical properties of a device
    • B81B3/0067—Mechanical properties
    • B81B3/007—For controlling stiffness, e.g. ribs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G5/00—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture
    • H01G5/01—Details
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/02—Sensors
    • B81B2201/0221—Variable capacitors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2203/00—Basic microelectromechanical structures
    • B81B2203/01—Suspended structures, i.e. structures allowing a movement
    • B81B2203/0118—Cantilevers

Definitions

  • the present invention relates to a variable capacitance device that can vary and change an RF (Radio Frequency) capacitance using a MEMS driven by electrostatic force.
  • RF Radio Frequency
  • FIG. 1 is a diagram illustrating a configuration example of a conventional variable capacitance device.
  • the variable capacity device 101 includes movable plates 102 and 103.
  • the movable plates 102 and 103 each have a doubly supported beam structure and are made of a conductive material.
  • the movable plate 102 and the movable plate 103 are spaced apart from each other.
  • the movable plate 103 has a convex surface facing the movable plate 102 and includes a dielectric layer 104 on the surface.
  • the distance between the movable plates 102 and 103 is narrowed by the driving capacity generated by applying the driving DC voltage between the movable plates 102 and 103, and the dielectric layer 104 is passed from the convex tip region of the movable plate 103 to the movable plate 102.
  • the RF capacity of the variable capacitance device 101 changes continuously according to the contact area.
  • electrostatic attraction by RF signal also acts, and electrostatic attraction by RF signal causes deformation (self-activation) of the beam structure.
  • By making the spring constant of the beam structure sufficiently large it becomes possible to suppress deformation due to self-activation, but in that case, deformation of the beam structure due to the drive DC voltage that is originally desired to be continuously changed is also suppressed. There is a need to increase the driving DC voltage, and there is a problem that the circuit configuration becomes large and complicated.
  • FIG. 2A is a side sectional view showing a configuration example of the variable capacitance device 201
  • FIG. 2B is a front sectional view thereof.
  • the variable capacity device 201 includes a support plate 202 and a movable beam 203.
  • the movable beam 203 has a cantilever configuration that is supported in parallel to the support plate 202.
  • a line-shaped electrode 204 is extended along both ends of the movable beam 203.
  • the line-shaped electrodes 204 provided on the support plate 202 and the movable beam 203 are opposed to each other through the dielectric film 205, and constitute the RF capacitor 206A or the drive capacitor 206B.
  • the drive capacity unit 206B functions as a drive capacity when a drive DC voltage is applied, and deforms the movable beam 203 so that the contact area with the dielectric film 205 is continuously changed.
  • the RF capacitor portion 206A is provided with two line-shaped electrodes 204 on the support plate 202 side, one line-shaped electrode 204 on the movable beam 203 side, and the two line-shaped electrodes 204 provided on the support plate 202 are connected to the RF signal.
  • the RF capacitor 206A By being connected to the signal line, it functions as an RF capacitor in which two capacitors are connected in series.
  • the electrostatic attractive force acting between the electrodes is suppressed (numerically reduced to about 1/4) and self-actuated as compared with the case where one set of counter electrodes is used as it is for the RF capacitor. Deformation of the beam structure due to actuation can be suppressed.
  • variable capacitance device that stabilizes the drive capacity by monitoring the drive capacity and performing feedback control of the drive DC voltage in order to prevent temperature changes and self-actuation from causing an error. Is going.
  • FIG. 2C shows a modified example of the movable beam 203 that is generated by reducing the spring constant in the direction orthogonal to the principal axis direction of the movable beam 203 when the movable beam 203 in the above-described variable capacitance device 201 is thinned.
  • FIG. 2C shows a modified example of the movable beam 203 that is generated by reducing the spring constant in the direction orthogonal to the principal axis direction of the movable beam 203 when the movable beam 203 in the above-described variable capacitance device 201 is thinned.
  • the RF capacitor portion 206A and the drive capacitor portion 206B are adjacent to each other in this direction, a difference occurs in the distance between the movable beam 203 and the support plate 202 between the RF capacitor portion 206A and the drive capacitor portion 206B due to the bending. The correlation between the change and the capacity change of the drive capacity is deviated. Then, even if the driving DC voltage is stable, the RF capacitance is not necessarily stable.
  • an object of the present invention is to generate a deviation in the correlation between the capacitance change of the drive capacitance and the capacitance change of the RF capacitance even if the drive DC voltage is reduced after suppressing the deformation of the beam structure due to self-activation. It is an object of the present invention to provide a variable capacitance device that can prevent this.
  • the first variable capacitance device of the present invention includes a support plate, a movable beam, a drive capacitance portion, and an RF capacitance portion.
  • the movable beam is supported in parallel to the main surface of the support plate.
  • the movable beam is made of a conductive material.
  • the drive capacitor unit includes a drive capacitor electrode provided on the support plate so as to face the movable beam, and a dielectric film formed between the movable beam and the drive capacitor electrode.
  • the drive capacity unit deforms the movable beam based on the drive capacity generated between the movable beam and the drive capacity electrode.
  • the RF capacitor portion is composed of an RF capacitor electrode provided on the support plate so as to face the movable beam, and a dielectric film formed between the movable beam and the RF capacitor electrode.
  • the RF capacitor unit propagates an RF signal through an RF capacitor generated between the movable beam and the RF capacitor electrode.
  • the movable beam has a locally small dimension in the thickness direction perpendicular to the main surface of the movable beam, and extends in a line shape in the width direction substantially perpendicular to the main axis direction and the thickness direction of the movable beam.
  • a line-shaped groove is provided, and a plurality of line-shaped grooves are arranged in the main axis direction at intervals.
  • a second variable capacitance device includes a support plate, a movable beam, a drive capacitance portion, and an RF capacitance portion.
  • the movable beam is supported in parallel to the main surface of the support plate.
  • the drive capacitor section includes a pair of drive capacitor electrodes provided on the movable beam and the support plate so as to face each other, and a dielectric film stacked on at least one of the pair of drive capacitor electrodes.
  • the drive capacity unit deforms the movable beam based on the drive capacity generated between the pair of drive capacity electrodes.
  • the RF capacitor unit includes a pair of RF capacitor electrodes provided opposite to each other on the movable beam and the support plate, and a dielectric film stacked on at least one of the pair of RF capacitor electrodes.
  • the RF capacitor unit propagates an RF signal through an RF capacitor generated between a pair of RF capacitor electrodes.
  • the movable beam has a locally small dimension in the thickness direction perpendicular to the main surface of the movable beam, and extends in a line shape in the width direction substantially perpendicular to the main axis direction and the thickness direction of the movable beam.
  • a line-shaped groove is provided, and a plurality of line-shaped grooves are arranged in the main axis direction at intervals.
  • the movable beam can be softened in the main axis direction and hardened in the width direction to prevent bending in the width direction, and to prevent a deviation from occurring in the correlation between the capacitance change of the RF capacitance and the capacitance change of the driving capacitance. Can do.
  • the variable capacitance device of the present invention preferably includes a drive circuit.
  • the drive circuit detects a detection voltage that changes according to the drive capacity, and controls the drive DC voltage so that the detection voltage approaches a desired value.
  • the drive capacity can be stabilized even when there is a disturbance such as deformation of the movable beam due to self-actuation or temperature change.
  • By preventing the movable beam from bending in the vertical direction it is possible to prevent the correlation between the change in the capacity of the drive capacity and the change in the capacity of the RF capacity from occurring. Can be stable.
  • the line-shaped groove may be formed by partially removing the constituent material, or the line-shaped groove may be formed by partially adding the constituent material.
  • the main shaft is secured while ensuring a spring constant in the width direction of the movable beam.
  • the spring constant in the direction can be reduced, and the driving DC voltage can be reduced while ensuring the correlation between the RF capacity and the driving capacity by preventing the bending in the width direction of the movable beam.
  • variable capacitance apparatus It is a figure explaining the structural example of the conventional variable capacitance apparatus. It is a figure explaining the structural example of another variable capacity apparatus. It is a figure explaining the example of composition of the variable capacity device concerning a 1st embodiment of the present invention. It is a figure explaining the structural example of the drive circuit of the variable capacitance apparatus which concerns on the 1st Embodiment of this invention. It is a figure explaining a part of manufacturing process of the variable capacitance apparatus which concerns on the 1st Embodiment of this invention. It is a figure explaining the structural example of the variable capacitance apparatus which concerns on the 2nd Embodiment of this invention. It is a figure explaining the structural example of the variable capacitance apparatus which concerns on the 3rd Embodiment of this invention.
  • variable capacitance device A configuration example of a variable capacitance device according to an embodiment of the present invention will be described with reference to the drawings.
  • an orthogonal coordinate XYZ axis is attached, the thickness direction of the movable beam is the Z-axis direction, the principal axis direction is the X-axis direction, and the width direction is the Y-axis direction.
  • FIG. 3A is an XY plane plan view of the variable capacitance device 1 according to the first embodiment of the present invention.
  • FIG. 3B is a cross-sectional view of the variable capacitance device 1 taken along the XZ plane.
  • FIG. 3C is a YZ plane cross-sectional view of the variable capacitance device 1.
  • the variable capacitance device 1 includes a support plate 2, lower RF capacitance electrodes 3 ⁇ / b> A and 3 ⁇ / b> B, lower drive capacitance electrodes 4 ⁇ / b> A and 4 ⁇ / b> B, a movable beam 6, and a dielectric film 5.
  • the support plate 2 is made of a rectangular glass substrate in plan view.
  • the movable beam 6 is made of a low-resistance silicon substrate (conductive material) using a dopant such as P (phosphorus), As (arsenic), or B (boron), and includes two connecting portions 6B, a movable portion 6A, and a supporting portion. 6C, and has a substantially L-shaped cantilever structure when viewed from the XZ plane.
  • the support portion 6C is long in the Y-axis direction, has a columnar shape standing in the Z-axis direction from the support plate 2, is provided at the X-axis negative direction end of the movable beam 6, and is connected to the connecting portion 6B.
  • the movable part 6 ⁇ / b> A is supported in a state of being separated from the support plate 2.
  • the movable portion 6A has a flat plate shape that is long in the X-axis direction when viewed from the XY plane, and is provided at the end portion of the movable beam 6 in the X-axis positive direction.
  • Each of the two connecting portions 6B has a meander line shape meandering with respect to the X-axis, and is erected in the X-axis direction from both ends in the Y-axis direction of the support portion 6C and between the support portion 6C and the movable portion 6A.
  • the support end of the movable beam 6 is supported as a rotation end instead of a fixed end.
  • the line-shaped ridges 6A1 and the line-shaped grooves 6A2 are alternately arranged in the X-axis direction on the upper surface (main surface in the positive Z-axis direction) of the movable part 6A, and each extends in the Y-axis direction. It is installed.
  • the line-shaped groove 6A2 is thinner than the line-shaped ridge 6A1, and such line-shaped grooves 6A2 are arranged in the X-axis direction at regular intervals. Thereby, the spring constant of the movable beam 6 in the X-axis direction can be reduced.
  • the line-shaped ridge 6A1 is thicker than the line-shaped groove 6A2, and such line-shaped ridges 6A1 are arranged in the X-axis direction at regular intervals.
  • the spring constant in the movable beam 6 other than in the X-axis direction, in particular, the spring constant in the Y-axis direction can be ensured to a certain degree. Therefore, the movable beam 6 is soft in the X-axis direction and hard in the Y-axis direction.
  • the lower RF capacitive electrodes 3A and 3B and the lower drive capacitive electrodes 4A and 4B are line-shaped electrodes that are formed on the upper surface of the support plate 2 and are long in the X-axis direction.
  • Lower drive capacitance electrodes 4A and 4B are arranged on both sides of 3B in the Y-axis direction.
  • the dielectric film 5 is made of tantalum pentoxide, and is laminated on the upper surface region of the support plate 2 so as to cover the lower RF capacitive electrodes 3A and 3B and the lower drive capacitive electrodes 4A and 4B.
  • the lower RF capacitive electrode 3A is connected to an RF signal input terminal (or output terminal), and the lower RF capacitive electrode 3B is connected to an RF signal output terminal (or input terminal).
  • the lower drive capacitance electrodes 4A and 4B are connected to a drive DC voltage terminal via a signal cut resistance element.
  • the movable beam 6 is connected to the ground GND via a resistance element for signal cut.
  • the lower RF capacitive electrodes 3A and 3B constitute RF capacitive portions C1A and C1B together with regions where the movable beam 6 and the dielectric film 5 face each other.
  • the lower drive capacitance electrodes 4A and 4B constitute drive capacitance portions C2A and C2B together with the opposing regions of the movable beam 6 and the dielectric film 5, respectively.
  • the drive capacitors C2A and C2B serve as drive capacitors that attract the movable beam 6 to the support plate 2 side by the electrostatic attractive force and bring the movable beam 6 into contact with the dielectric film 5 from the tip (end on the X axis positive direction side). Function.
  • the higher the driving DC voltage the larger the contact area between the movable beam 6 and the dielectric film 5.
  • the RF capacitors C1A and C1B are used in a high-frequency circuit of several hundred MHz to several GHz, and function as RF capacitors whose capacitance changes depending on the contact area between the movable beam 6 and the dielectric film 5. .
  • the electrostatic attraction per unit area is larger than the configuration in which the drive capacitors C2A and C2B are connected in series. This is more advantageous than the case in reducing the electrode area.
  • the RF capacitors C1A and C1B are connected in series between the RF signal input terminal and the output terminal, the electrostatic attraction per unit area is smaller than the configuration in which both are connected in parallel, and the two are connected in parallel. This is more advantageous for suppressing the deformation (self-actuation) of the movable beam 6 due to the RF signal than the case of doing so.
  • FIG. 4A is a diagram illustrating a configuration example of the drive circuit 11 of the variable capacitance device 1.
  • the drive circuit 11 includes a drive DC voltage control circuit 12, a capacitance detection AC signal source 13, an amplifier circuit 14, a rectifier circuit 15, and a comparator 16.
  • the drive DC voltage control circuit 12 outputs a drive DC voltage.
  • the capacitance detection AC signal source 13 superimposes a capacitance detection AC signal of about 10 MHz on the driving DC voltage. This superimposed signal is applied to a capacitance circuit including the drive capacitance units C2A and C2B of the variable capacitance device 1.
  • This capacitor circuit has a configuration in which a parallel circuit composed of a DC bypass resistor R2 and a reference capacitor unit C4 and a parallel circuit composed of drive capacitor units C2A and C2B of the variable capacitor device 1 are connected in series.
  • the capacitance values of the drive capacitance units C2A and C2B are determined by the DC component of the superimposed signal, and the deformation amount of the movable beam 6 in the variable capacitance device 1 is determined.
  • the AC component of the superimposed signal is output to the amplifier circuit 14 as an amplitude corresponding to the capacitance ratio between the capacitance value of the combined capacitance of the drive capacitance units C2A and C2B and the capacitance value of the reference capacitance unit C4.
  • the amplifier circuit 14 amplifies the AC output from the capacitor circuit, and the rectifier circuit 15 rectifies the AC output from the amplifier circuit 14, and a voltage level detection signal (monitor signal) reflecting the combined capacitance of the drive capacitor units C2A and C2B.
  • the comparator 16 receives an external input signal for instructing the capacitance setting values of the drive capacitor units C2A and C2B, compares the voltage level of the detection signal and the external input signal, and outputs to switch to the LOW level or the HIGH level. Output voltage.
  • the drive DC voltage control circuit 12 increases or decreases the drive DC voltage according to the output voltage of the comparator 16 and outputs it.
  • the drive capacitance units C2A and C2B are configured to perform feedback control, and the RF capacitance units C1A and C1B are configured to be connected in series as described above. Therefore, in the variable capacitance device 1, the influence of self-activation is extremely high.
  • the drive DC voltage can be lowered by reducing the spring constant of the movable beam 6 in the principal axis direction.
  • FIG. 4B is a diagram illustrating drive DC voltage-RF capacitance characteristics of the variable capacitance device 1 driven by the drive circuit 11.
  • the driving DC voltage-RF capacitance characteristic in the configuration of the present embodiment is displayed by a solid line
  • the driving DC voltage-RF capacitance characteristic in a comparative configuration in which the thickness of the movable portion 6A is uniform is displayed by a dotted line. Yes.
  • the movable beam 6 is in a state of being separated from the dielectric film 5 in the range where the driving DC voltage is from zero to the first threshold value, and even if the driving DC voltage changes, the RF capacitance Hardly changes.
  • the driving DC voltage becomes the first threshold value
  • the tip of the movable beam 6 comes into contact with the dielectric film 5, and the RF capacitance is greatly increased.
  • the drive DC voltage is in the range from the first threshold value to the second threshold value
  • the contact area between the movable beam 6 and the dielectric film 5 changes linearly according to the drive DC voltage, and the contact area increases as the drive DC voltage increases. Increase, which increases the RF capacity.
  • the contact area between the movable beam 6 and the dielectric film 5 is maximized, and the RF capacity is also maximized. Even if the drive DC voltage increases beyond the second threshold, the contact area between the movable beam 6 and the dielectric film 5 remains maximized, and the RF capacitance hardly changes.
  • the movable beam 6 is soft in the X-axis direction as described above, and the spring constant in the X-axis direction of the movable beam 6 is small, so that the tip of the movable beam 6 is smaller than the comparative configuration.
  • the first threshold value of the driving DC voltage that contacts the dielectric film 5 and the second threshold value of the driving DC voltage that maximizes the contact area between the movable beam 6 and the dielectric film 5 are small. Therefore, the movable beam 6 can be appropriately deformed even when the driving DC voltage is lowered.
  • the drive DC voltage can be lowered without causing a deviation in the correlation between the capacitance change of the drive capacitor portions C2A and C2B and the capacitance change of the RF capacitor portions C1A and C1B.
  • FIG. 5 is a schematic diagram illustrating an example of a process of processing the movable beam 6 in the manufacturing process of the variable capacitance device 1.
  • a large-area wafer-like low-resistance silicon mother substrate 36 and a glass mother substrate 32 are prepared.
  • Lower RF capacitive electrodes 3A and 3B, lower drive capacitive electrodes 4A and 4B, and dielectric film 5 are formed on glass mother substrate 32, and projecting as support portion 6C on low-resistance silicon mother substrate 36. A part is formed, and both are bonded by an anodic bonding method or a cleaning bonding method.
  • the first mask layer 37 is formed on the upper surface of the low resistance silicon mother substrate 36 in the same pattern shape as the line-shaped ridge 6A1 (S1).
  • the first mask layer 37 is made of, for example, Al or SiO 2 , and adopts a material capable of obtaining selectivity with silicon by an etchant in a subsequent secondary etching process.
  • a second mask layer 38 is formed in the same pattern shape as the movable beam 6 on the upper surfaces of the low-resistance silicon mother substrate 36 and the first mask layer 37 (S2).
  • the second mask layer 38 is made of, for example, a positive resist material, and a material capable of obtaining selectivity with silicon by an etchant is used in a subsequent primary etching process.
  • a primary etching process for dry etching the low resistance silicon mother substrate 36 is performed (S3).
  • the low resistance silicon mother substrate 36 is partially removed leaving a region covered with the second mask layer 38, and a plurality of movable beams 6 including the support portion 6C, the connecting portion 6B, and the movable portion 6A are formed.
  • the second mask layer 38 is removed by O 2 ashing (S4).
  • a secondary etching step for dry etching the movable portion 6A is performed (S5).
  • the movable portion 6A is removed by a certain thickness while leaving the line-shaped ridge 6A1 covered by the first mask layer 37, and the line-shaped groove 6A2 is formed.
  • the first mask layer 37 is removed by wet etching (S6).
  • the support plate 2 is cut out by dicing the glass mother substrate 32 to manufacture a plurality of variable capacitance devices 1.
  • variable capacitance device 1 of the present embodiment is manufactured through the above manufacturing process, but by using dry etching of a low resistance silicon substrate for forming the line-shaped ridge 6A1 and the line-shaped groove 6A2 in the movable beam 6, Line width processing accuracy can be improved, and fine processing of about 1um is possible. Note that wet etching may be used instead of dry etching, and in this case, processing can be performed at a lower cost than dry etching.
  • FIG. 6A is an XY plane plan view of the variable capacitance device 41 according to the second embodiment of the present invention.
  • FIG. 6B is a cross-sectional view of the variable capacitance device 41 taken along the XZ plane.
  • FIG. 6C is a YZ plane cross-sectional view of the variable capacitance device 41.
  • the variable capacitance device 41 of this embodiment includes a movable beam 46.
  • the movable beam 46 includes a movable part 46A, a beam-like part 46B, and a support part 46C. Then, on the upper surface (main surface in the positive Z-axis direction) of the movable portion 46A, the line-shaped ridge portions 46A1 and the line-shaped groove portions 46A2 are alternately arranged in the X-axis direction, and each extend in the Y-axis direction. Yes.
  • the movable portion 46A is not formed of an integral low-resistance silicon substrate, but is composed of a flat layer 47A made of low-resistance silicon and an additional layer 47B laminated on the upper surface of the flat layer 47A.
  • the additional layer 47B has a plurality of grooves that extend in the Y-axis direction and are arranged at predetermined intervals in the X-axis direction. Any material may be used for the additional layer 47B, but a material having a large Young's modulus is preferable. For a metal film, a tungsten film, a molybdenum film, a platinum film, or the like is used as an insulating film. If so, a SiO 2 film or the like can be employed. Further, for the patterning of the additional layer 47B, a method such as a lift-off method or a plating method can be employed.
  • variable capacitance device 41 of this embodiment adds an additional layer 47B to the upper surface of the flat plate layer 47A, compared to a configuration in which the constituent members of the movable beam are partially removed by grooving as in the first embodiment. Therefore, it is difficult to cause structural defects in the movable beam itself, and even a material that is difficult to grooving can be adopted as a constituent material. Therefore, various materials such as metal materials such as gold and copper, SiO 2 , SiN, poly-Si, and polycrystalline diamond can be used as the main constituent material of the movable beam.
  • FIG. 7A is an XZ plane cross-sectional view of the variable capacitance device 51 according to the third embodiment of the present invention.
  • FIG. 7B is a YZ plane cross-sectional view of the variable capacitance device 51.
  • the variable capacitance device 51 of this embodiment includes a movable beam 56 made of an insulating material.
  • the movable beam 56 includes a movable portion 56A, a beam-shaped portion 56B, and a support portion 56C.
  • the movable beam 56 has a line-shaped ridge portion and a line-shaped groove portion, like the movable beam 6 of the first embodiment described above.
  • the variable capacitance device 51 of the present embodiment is configured to include an upper RF capacitance electrode 57A and upper drive capacitance electrodes 57B and 57C that are patterned on the lower surface of the movable beam 56.
  • the upper RF capacitive electrode 57A and the upper drive capacitive electrodes 57B and 57C are line-shaped electrodes that are formed on the lower surface of the movable beam 56 and are long in the X-axis direction.
  • the upper RF capacitive electrode 57A is provided so as to face the lower RF capacitive electrodes 3A and 3B.
  • the upper drive capacitance electrodes 57B and 57C are provided so as to face the lower drive capacitance electrodes 4A and 4B, respectively.
  • the upper RF capacitive electrode 57A, together with the opposing regions of the lower RF capacitive electrodes 3A and 3B and the dielectric film 5, constitutes RF capacitive portions C1A and C1B.
  • the upper drive capacitance electrodes 57B and 57C constitute drive capacitance portions C2A and C2B together with the opposing regions of the lower drive capacitance electrodes 4A and 4B and the dielectric film 5, respectively.
  • the RF capacitors C1A and C1B and the drive capacitors C2A and C2B can be electrically separated, which is necessary when using a movable beam of conductive material as in the above-described embodiment.
  • the element for signal cut is not an essential component for the drive circuit, and the circuit configuration of the drive circuit can be simplified.
  • the movable beam has been described as a cantilever beam structure.
  • the movable beam may be a double-sided beam structure or a cantilever structure.
  • the present invention can be suitably implemented.
  • the cross-sectional shape of the line-shaped groove portion has been described as a rectangular shape, various shapes can be adopted as the cross-sectional shape.
  • the present invention is not limited to the description of the embodiments, and the scope of the present invention is defined by the scope of the claims, and includes all modifications within the meaning and scope equivalent to the scope of the claims. Is intended.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Mechanical Engineering (AREA)
  • Computer Hardware Design (AREA)
  • Micromachines (AREA)

Abstract

The disclosed variable capacitance device (1) is provided with a support board (2), a movable beam (6), underside RF capacitance electrodes (3A, 3B) and underside drive capacitance electrodes (4A, 4B). The movable beam (6) is disposed parallel to the main surface of the support board (2) and is connected to the support board (2). The underside RF capacitance electrodes (3A, 3B) and the underside drive capacitance electrodes (4A, 4B) are formed on the support board (2) with the length dimension thereof aligned with the axial direction of the movable beam (6). The underside drive capacitance electrodes (4A, 4B) deform the moveable beam (6) on the basis of drive capacitance formed between the movable beam (6) and the drive capacitance electrodes (4A, 4B). The underside RF capacitance electrodes (3A, 3B) propagate an RF signal via RF capacitance occurring between the movable beam (6) and the RF capacitance electrodes (3A, 3B). The movable beam (6) is thin along the Z-axis, and is provided with track-like gutters (6A2) that extend along the Y-axis, with the multiple track-like gutters (6A2) being arranged parallel to each other at intervals.

Description

可変容量装置Variable capacity device
　この発明は、静電力により駆動するＭＥＭＳを用いてＲＦ（Ｒａｄｉｏ　Ｆｒｅｑｕｅｎｃｙ）容量を可変する変えることができる可変容量装置に関するものである。 The present invention relates to a variable capacitance device that can vary and change an RF (Radio Frequency) capacitance using a MEMS driven by electrostatic force.
　近年、可変容量装置に静電力により駆動するＭＥＭＳが利用されることがある（特許文献１，２参照。）。 In recent years, MEMS driven by electrostatic force is sometimes used for variable capacitance devices (see Patent Documents 1 and 2).
　図１は、従来の可変容量装置の構成例を説明する図である。
　可変容量装置１０１は、可動板１０２，１０３を備える。可動板１０２，１０３はそれぞれ両持ち梁構造であり、導電性材料からなる。可動板１０２と可動板１０３とは、互いに間隔を隔てて配置されている。可動板１０３は、可動板１０２との対向面が凸形状であり、誘電体層１０４を表面に備える。可動板１０２，１０３間に駆動ＤＣ電圧を印加することで生じる駆動容量によって、可動板１０２，１０３間の間隔が狭まって可動板１０３の凸形状先端領域から可動板１０２に誘電体層１０４を介して接触し、接触面積に応じて可変容量装置１０１のＲＦ容量が連続的に変わる。 FIG. 1 is a diagram illustrating a configuration example of a conventional variable capacitance device.
The variable capacity device 101 includes movable plates 102 and 103. The movable plates 102 and 103 each have a doubly supported beam structure and are made of a conductive material. The movable plate 102 and the movable plate 103 are spaced apart from each other. The movable plate 103 has a convex surface facing the movable plate 102 and includes a dielectric layer 104 on the surface. The distance between the movable plates 102 and 103 is narrowed by the driving capacity generated by applying the driving DC voltage between the movable plates 102 and 103, and the dielectric layer 104 is passed from the convex tip region of the movable plate 103 to the movable plate 102. The RF capacity of the variable capacitance device 101 changes continuously according to the contact area.
特開２００６－２１０８４３号公報Japanese Patent Laid-Open No. 2006-210843 特開２００８－１８２１３４号公報JP 2008-182134 A
　可変容量装置では、ＲＦ信号による静電引力も作用し、ＲＦ信号による静電引力が梁構造の変形（セルフアクチエーション）を引き起こす。このことが駆動ＤＣ電圧によるＲＦ容量の制御精度を低下させる。梁構造のバネ定数を十分に大きくすることでセルフアクチエーションによる変形を抑制することが可能になるが、その場合、本来連続的に変化させたい駆動ＤＣ電圧による梁構造の変形も抑制されるため駆動ＤＣ電圧を高電圧化する必要が生じ、回路構成が大型化、複雑化する問題がある。 In the variable capacitance device, electrostatic attraction by RF signal also acts, and electrostatic attraction by RF signal causes deformation (self-activation) of the beam structure. This reduces the control accuracy of the RF capacitance by the driving DC voltage. By making the spring constant of the beam structure sufficiently large, it becomes possible to suppress deformation due to self-activation, but in that case, deformation of the beam structure due to the drive DC voltage that is originally desired to be continuously changed is also suppressed. There is a need to increase the driving DC voltage, and there is a problem that the circuit configuration becomes large and complicated.
　そこで本願出願人は、上記セルフアクチエーションによる梁構造の変形を抑制できる可変容量装置の開発を行っている。図２（Ａ）はその可変容量装置２０１の構成例を示す側面断面図であり、図２（Ｂ）はその正面断面図である。
　可変容量装置２０１は、支持板２０２と可動梁２０３とを備える。可動梁２０３は、支持板２０２に対して平行に支持される片持ち梁構成である。可動梁２０３と支持板２０２とのそれぞれには、可動梁２０３の両端間に沿って線路状電極２０４を延設する。支持板２０２と可動梁２０３とのそれぞれに設けられた線路状電極２０４は、誘電体膜２０５を介して対向し、ＲＦ容量部２０６Ａまたは駆動容量部２０６Ｂを構成する。駆動容量部２０６Ｂは、駆動ＤＣ電圧が印加されることで駆動容量として機能し、誘電体膜２０５との接触面積が連続変化するように可動梁２０３を変形させる。ＲＦ容量部２０６Ａは、支持板２０２側に線路状電極２０４を２つ設け、可動梁２０３側に線路状電極２０４を１つ設け、支持板２０２に設けられる２つの線路状電極２０４がＲＦ信号の信号ラインに接続されることで、２つの容量を直列接続したＲＦ容量として機能するものである。このＲＦ容量部２０６Ａの構成では、１組の対向電極をそのままＲＦ容量に利用する場合よりも、電極間に作用する静電引力を抑制（数式的にはおよそ１／４に）して、セルフアクチエーションによる梁構造の変形を抑制することが可能になる。 Therefore, the applicant of the present application has developed a variable capacitance device that can suppress the deformation of the beam structure due to the self-activation. FIG. 2A is a side sectional view showing a configuration example of the variable capacitance device 201, and FIG. 2B is a front sectional view thereof.
The variable capacity device 201 includes a support plate 202 and a movable beam 203. The movable beam 203 has a cantilever configuration that is supported in parallel to the support plate 202. On each of the movable beam 203 and the support plate 202, a line-shaped electrode 204 is extended along both ends of the movable beam 203. The line-shaped electrodes 204 provided on the support plate 202 and the movable beam 203 are opposed to each other through the dielectric film 205, and constitute the RF capacitor 206A or the drive capacitor 206B. The drive capacity unit 206B functions as a drive capacity when a drive DC voltage is applied, and deforms the movable beam 203 so that the contact area with the dielectric film 205 is continuously changed. The RF capacitor portion 206A is provided with two line-shaped electrodes 204 on the support plate 202 side, one line-shaped electrode 204 on the movable beam 203 side, and the two line-shaped electrodes 204 provided on the support plate 202 are connected to the RF signal. By being connected to the signal line, it functions as an RF capacitor in which two capacitors are connected in series. In the configuration of the RF capacitor 206A, the electrostatic attractive force acting between the electrodes is suppressed (numerically reduced to about 1/4) and self-actuated as compared with the case where one set of counter electrodes is used as it is for the RF capacitor. Deformation of the beam structure due to actuation can be suppressed.
　また、本願出願人は、温度変化やセルフアクチエーションなどが誤差要因となることを防ぐために、駆動容量をモニターして駆動ＤＣ電圧をフィードバック制御し、駆動容量を安定化する可変容量装置の開発も行っている。 The applicant of the present application has also developed a variable capacitance device that stabilizes the drive capacity by monitoring the drive capacity and performing feedback control of the drive DC voltage in order to prevent temperature changes and self-actuation from causing an error. Is going.
　このような様々な対策によって、可変容量装置におけるセルフアクチエーションによる梁構造の変形を抑制することが可能になり、可動梁のバネ定数を低減して駆動ＤＣ電圧を低電圧化することが可能になる。 These various measures make it possible to suppress deformation of the beam structure due to self-activation in the variable capacitance device, and to reduce the spring constant of the movable beam and lower the drive DC voltage. Become.
　しかしながら、可動梁のバネ定数を低減するために可動梁を一様に薄くした場合、可動梁の主軸方向のバネ定数だけではなく全方向でバネ定数が低減し、可変容量装置に新たな問題を引き起こすことになる。
　図２（Ｃ）は、上述の可変容量装置２０１における可動梁２０３を薄くした場合に、可動梁２０３の主軸方向に直交する方向のバネ定数が低減することによって生じる可動梁２０３の変形例を示す図である。可動梁２０３の主軸方向に直交する方向でのバネ定数が低減すると、その方向での撓みが生じ易くなる。ＲＦ容量部２０６Ａと駆動容量部２０６Ｂとはこの方向に隣接するため、撓みによってＲＦ容量部２０６Ａと駆動容量部２０６Ｂとで可動梁２０３と支持板２０２との間隔に差が生じ、ＲＦ容量の容量変化と駆動容量の容量変化との相関性がずれてしまう。すると、たとえ駆動ＤＣ電圧が安定であってもＲＦ容量は、必ずしも安定ではなくなってしまう。 However, if the movable beam is uniformly thinned to reduce the spring constant of the movable beam, the spring constant is reduced not only in the main beam direction of the movable beam but also in all directions, which creates a new problem for the variable capacity device. Will cause.
FIG. 2C shows a modified example of the movable beam 203 that is generated by reducing the spring constant in the direction orthogonal to the principal axis direction of the movable beam 203 when the movable beam 203 in the above-described variable capacitance device 201 is thinned. FIG. When the spring constant in the direction orthogonal to the principal axis direction of the movable beam 203 is reduced, bending in that direction is likely to occur. Since the RF capacitor portion 206A and the drive capacitor portion 206B are adjacent to each other in this direction, a difference occurs in the distance between the movable beam 203 and the support plate 202 between the RF capacitor portion 206A and the drive capacitor portion 206B due to the bending. The correlation between the change and the capacity change of the drive capacity is deviated. Then, even if the driving DC voltage is stable, the RF capacitance is not necessarily stable.
　そこで、本発明の目的は、セルフアクチエーションによる梁構造の変形を抑制した上で駆動ＤＣ電圧を低減しても、駆動容量の容量変化とＲＦ容量の容量変化との相関性にずれが発生することを防ぐことが可能な可変容量装置を提供することにある。 Therefore, an object of the present invention is to generate a deviation in the correlation between the capacitance change of the drive capacitance and the capacitance change of the RF capacitance even if the drive DC voltage is reduced after suppressing the deformation of the beam structure due to self-activation. It is an object of the present invention to provide a variable capacitance device that can prevent this.
　この発明の第１の可変容量装置は、支持板と、可動梁と、駆動容量部と、ＲＦ容量部とを備える。可動梁は、支持板の主面に平行に支持される。可動梁は、導電性材料からなる。駆動容量部は、可動梁に対向するように支持板に設けられる駆動容量電極と、可動梁と駆動容量電極との間に形成される誘電体膜とからなる。駆動容量部は、可動梁と駆動容量電極との間に生じる駆動容量に基づいて可動梁を変形させる。ＲＦ容量部は、可動梁に対向するように支持板に設けられるＲＦ容量電極と、可動梁とＲＦ容量電極との間に形成される誘電体膜とからなる。ＲＦ容量部は、可動梁とＲＦ容量電極との間に生じるＲＦ容量を介してＲＦ信号を伝搬させる。このような可変容量装置において可動梁は、可動梁の主面に垂直な厚み方向の寸法が局所的に小さく可動梁における主軸方向および厚み方向と略垂直な幅方向に線路状に延設される線路状溝部を備え、複数の線路状溝部を間隔を隔てて主軸方向に配列させた構成である。 The first variable capacitance device of the present invention includes a support plate, a movable beam, a drive capacitance portion, and an RF capacitance portion. The movable beam is supported in parallel to the main surface of the support plate. The movable beam is made of a conductive material. The drive capacitor unit includes a drive capacitor electrode provided on the support plate so as to face the movable beam, and a dielectric film formed between the movable beam and the drive capacitor electrode. The drive capacity unit deforms the movable beam based on the drive capacity generated between the movable beam and the drive capacity electrode. The RF capacitor portion is composed of an RF capacitor electrode provided on the support plate so as to face the movable beam, and a dielectric film formed between the movable beam and the RF capacitor electrode. The RF capacitor unit propagates an RF signal through an RF capacitor generated between the movable beam and the RF capacitor electrode. In such a variable capacity device, the movable beam has a locally small dimension in the thickness direction perpendicular to the main surface of the movable beam, and extends in a line shape in the width direction substantially perpendicular to the main axis direction and the thickness direction of the movable beam. A line-shaped groove is provided, and a plurality of line-shaped grooves are arranged in the main axis direction at intervals.
　この発明の第２の可変容量装置は、支持板と、可動梁と、駆動容量部と、ＲＦ容量部とを備える。可動梁は、支持板の主面に平行に支持される。駆動容量部は、可動梁と支持板とに互いに対向して設けられる一対の駆動容量電極と、一対の駆動容量電極の少なくとも一方に積層される誘電体膜とからなる。駆動容量部は、一対の駆動容量電極の間に生じる駆動容量に基づいて可動梁を変形させる。ＲＦ容量部は、可動梁と支持板とに互いに対向して設けられる一対のＲＦ容量電極と、一対のＲＦ容量電極の少なくとも一方に積層される誘電体膜とからなる。ＲＦ容量部は、一対のＲＦ容量電極の間に生じるＲＦ容量を介してＲＦ信号を伝搬させる。このような可変容量装置において可動梁は、可動梁の主面に垂直な厚み方向の寸法が局所的に小さく可動梁における主軸方向および厚み方向と略垂直な幅方向に線路状に延設される線路状溝部を備え、複数の線路状溝部を間隔を隔てて主軸方向に配列させた構成である。
　これらの構成では、可動梁における幅方向に線路状に延設される複数の線路状溝部を主軸方向に間隔を隔てて配列させることで、可動梁の幅方向におけるバネ定数をある程度確保しながら、主軸方向におけるバネ定数を大幅に低減できる。即ち、可動梁を主軸方向に柔らかく幅方向に硬くして、幅方向での撓みを防ぐことができ、ＲＦ容量の容量変化と駆動容量の容量変化との相関性にずれが生じることを防ぐことができる。 A second variable capacitance device according to the present invention includes a support plate, a movable beam, a drive capacitance portion, and an RF capacitance portion. The movable beam is supported in parallel to the main surface of the support plate. The drive capacitor section includes a pair of drive capacitor electrodes provided on the movable beam and the support plate so as to face each other, and a dielectric film stacked on at least one of the pair of drive capacitor electrodes. The drive capacity unit deforms the movable beam based on the drive capacity generated between the pair of drive capacity electrodes. The RF capacitor unit includes a pair of RF capacitor electrodes provided opposite to each other on the movable beam and the support plate, and a dielectric film stacked on at least one of the pair of RF capacitor electrodes. The RF capacitor unit propagates an RF signal through an RF capacitor generated between a pair of RF capacitor electrodes. In such a variable capacitance device, the movable beam has a locally small dimension in the thickness direction perpendicular to the main surface of the movable beam, and extends in a line shape in the width direction substantially perpendicular to the main axis direction and the thickness direction of the movable beam. A line-shaped groove is provided, and a plurality of line-shaped grooves are arranged in the main axis direction at intervals.
In these configurations, by arranging a plurality of line-shaped groove portions extending in a line shape in the width direction in the movable beam at intervals in the main axis direction, while ensuring a certain spring constant in the width direction of the movable beam, The spring constant in the main axis direction can be greatly reduced. That is, the movable beam can be softened in the main axis direction and hardened in the width direction to prevent bending in the width direction, and to prevent a deviation from occurring in the correlation between the capacitance change of the RF capacitance and the capacitance change of the driving capacitance. Can do.
　この発明の可変容量装置は、駆動回路を備えると好適である。駆動回路は、駆動容量に応じて変化する検出電圧を検出し、その検出電圧が所望値に近づくように駆動ＤＣ電圧を制御する。
　駆動容量をモニターして駆動ＤＣ電圧をフィードバック制御することにより、セルフアクチュエーションによる可動梁の変形や、温度変化などの外乱があっても、駆動容量を安定にすることができる。可動梁の垂直方向での撓みを防ぐことで駆動容量の容量変化とＲＦ容量の容量変化との相関性にずれが生じることが防がれるため、この構成によって、駆動容量だけでなくＲＦ容量も安定にすることができる。 The variable capacitance device of the present invention preferably includes a drive circuit. The drive circuit detects a detection voltage that changes according to the drive capacity, and controls the drive DC voltage so that the detection voltage approaches a desired value.
By monitoring the drive capacity and performing feedback control of the drive DC voltage, the drive capacity can be stabilized even when there is a disturbance such as deformation of the movable beam due to self-actuation or temperature change. By preventing the movable beam from bending in the vertical direction, it is possible to prevent the correlation between the change in the capacity of the drive capacity and the change in the capacity of the RF capacity from occurring. Can be stable.
　この発明の可動梁は、構成材料の部分的除去により線路状溝部が形成されていてもよく、構成材料の部分的付加により線路状溝部が形成されていてもよい。 In the movable beam of the present invention, the line-shaped groove may be formed by partially removing the constituent material, or the line-shaped groove may be formed by partially adding the constituent material.
　この発明によれば、可動梁の幅方向に線路状に延設される複数の線路状溝部を主軸方向に間隔を隔てて配列させることで、可動梁における幅方向のバネ定数を確保しながら主軸方向のバネ定数を低減することができ、可動梁の幅方向での撓みを防いでＲＦ容量と駆動容量との相関性を確保しながら駆動ＤＣ電圧を低減できる。 According to the present invention, by arranging a plurality of line-shaped groove portions extending in a line shape in the width direction of the movable beam at intervals in the main axis direction, the main shaft is secured while ensuring a spring constant in the width direction of the movable beam. The spring constant in the direction can be reduced, and the driving DC voltage can be reduced while ensuring the correlation between the RF capacity and the driving capacity by preventing the bending in the width direction of the movable beam.
従来の可変容量装置の構成例を説明する図である。It is a figure explaining the structural example of the conventional variable capacitance apparatus. 他の可変容量装置の構成例を説明する図である。It is a figure explaining the structural example of another variable capacity apparatus. 本発明の第１の実施形態に係る可変容量装置の構成例を説明する図である。It is a figure explaining the example of composition of the variable capacity device concerning a 1st embodiment of the present invention. 本発明の第１の実施形態に係る可変容量装置の駆動回路の構成例を説明する図である。It is a figure explaining the structural example of the drive circuit of the variable capacitance apparatus which concerns on the 1st Embodiment of this invention. 本発明の第１の実施形態に係る可変容量装置の製造工程の一部を説明する図である。It is a figure explaining a part of manufacturing process of the variable capacitance apparatus which concerns on the 1st Embodiment of this invention. 本発明の第２の実施形態に係る可変容量装置の構成例を説明する図である。It is a figure explaining the structural example of the variable capacitance apparatus which concerns on the 2nd Embodiment of this invention. 本発明の第３の実施形態に係る可変容量装置の構成例を説明する図である。It is a figure explaining the structural example of the variable capacitance apparatus which concerns on the 3rd Embodiment of this invention.
　本発明の実施形態に係る可変容量装置の構成例について、図を参照して説明する。なお、各図には直交座標形のＸ－Ｙ－Ｚ軸を付し、可動梁の厚み方向をＺ軸方向、主軸方向をＸ軸方向、幅方向をＹ軸方向とする。 A configuration example of a variable capacitance device according to an embodiment of the present invention will be described with reference to the drawings. In each figure, an orthogonal coordinate XYZ axis is attached, the thickness direction of the movable beam is the Z-axis direction, the principal axis direction is the X-axis direction, and the width direction is the Y-axis direction.
《第１の実施形態》
　図３（Ａ）は、本発明の第１の実施形態に係る可変容量装置１のＸ－Ｙ面平面図である。図３（Ｂ）は、可変容量装置１のＸ－Ｚ面断面図である。図３（Ｃ）は、可変容量装置１のＹ－Ｚ面断面図である。 << First Embodiment >>
FIG. 3A is an XY plane plan view of the variable capacitance device 1 according to the first embodiment of the present invention. FIG. 3B is a cross-sectional view of the variable capacitance device 1 taken along the XZ plane. FIG. 3C is a YZ plane cross-sectional view of the variable capacitance device 1.
　可変容量装置１は、支持板２と、下側ＲＦ容量電極３Ａ，３Ｂと、下側駆動容量電極４Ａ，４Ｂと、可動梁６と、誘電体膜５とを備える。
　支持板２は、平面視して矩形状のガラス基板からなる。
　可動梁６は、Ｐ（リン）やＡｓ（ヒ素）、Ｂ（ホウ素）などのドーパントを用いた低抵抗シリコン基板（導電性材料）からなり、２本の連結部６Ｂと可動部６Ａと支持部６Ｃとを備え、Ｘ－Ｚ面を視て略Ｌ字状の片持ち梁構造である。支持部６Ｃは、Ｙ軸方向に長尺であって、支持板２からＺ軸方向に立設する柱状であり、可動梁６のＸ軸負方向端部に設けられていて、連結部６Ｂと可動部６Ａとを支持板２から離間した状態で支持する。可動部６Ａは、Ｘ－Ｙ面を視てＸ軸方向に長尺な平板状であり、可動梁６のＸ軸正方向端部に設けられている。２本の連結部６Ｂは、それぞれＸ軸に対して蛇行するミアンダライン状であり、支持部６ＣのＹ軸方向両端からＸ軸方向に立設して支持部６Ｃと可動部６Ａとの間を接続し、可動梁６の支持端を固定端ではなく回転端として支持する。 The variable capacitance device 1 includes a support plate 2, lower RF capacitance electrodes 3 </ b> A and 3 </ b> B, lower drive capacitance electrodes 4 </ b> A and 4 </ b> B, a movable beam 6, and a dielectric film 5.
The support plate 2 is made of a rectangular glass substrate in plan view.
The movable beam 6 is made of a low-resistance silicon substrate (conductive material) using a dopant such as P (phosphorus), As (arsenic), or B (boron), and includes two connecting portions 6B, a movable portion 6A, and a supporting portion. 6C, and has a substantially L-shaped cantilever structure when viewed from the XZ plane. The support portion 6C is long in the Y-axis direction, has a columnar shape standing in the Z-axis direction from the support plate 2, is provided at the X-axis negative direction end of the movable beam 6, and is connected to the connecting portion 6B. The movable part 6 </ b> A is supported in a state of being separated from the support plate 2. The movable portion 6A has a flat plate shape that is long in the X-axis direction when viewed from the XY plane, and is provided at the end portion of the movable beam 6 in the X-axis positive direction. Each of the two connecting portions 6B has a meander line shape meandering with respect to the X-axis, and is erected in the X-axis direction from both ends in the Y-axis direction of the support portion 6C and between the support portion 6C and the movable portion 6A. The support end of the movable beam 6 is supported as a rotation end instead of a fixed end.
　本実施形態では、可動部６Ａの上面（Ｚ軸正方向の主面）には、線路状稜部６Ａ１と線路状溝部６Ａ２とがＸ軸方向に交互に配列され、それぞれがＹ軸方向に延設されている。線路状溝部６Ａ２は線路状稜部６Ａ１よりも薄く、このような線路状溝部６Ａ２が一定間隔でＸ軸方向に配列されている。これにより、可動梁６におけるＸ軸方向のバネ定数を低減することができる。また、線路状稜部６Ａ１は線路状溝部６Ａ２よりも厚く、このような線路状稜部６Ａ１が一定間隔でＸ軸方向に配列されている。これにより、可動梁６におけるＸ軸方向以外でのバネ定数、特にＹ軸方向のバネ定数をある程度の大きさで確保することができる。したがって、この可動梁６はＸ軸方向に柔らかくＹ軸方向に硬い構成となっている。 In the present embodiment, the line-shaped ridges 6A1 and the line-shaped grooves 6A2 are alternately arranged in the X-axis direction on the upper surface (main surface in the positive Z-axis direction) of the movable part 6A, and each extends in the Y-axis direction. It is installed. The line-shaped groove 6A2 is thinner than the line-shaped ridge 6A1, and such line-shaped grooves 6A2 are arranged in the X-axis direction at regular intervals. Thereby, the spring constant of the movable beam 6 in the X-axis direction can be reduced. The line-shaped ridge 6A1 is thicker than the line-shaped groove 6A2, and such line-shaped ridges 6A1 are arranged in the X-axis direction at regular intervals. As a result, the spring constant in the movable beam 6 other than in the X-axis direction, in particular, the spring constant in the Y-axis direction can be ensured to a certain degree. Therefore, the movable beam 6 is soft in the X-axis direction and hard in the Y-axis direction.
　下側ＲＦ容量電極３Ａ，３Ｂと下側駆動容量電極４Ａ，４Ｂとは、それぞれ支持板２の上面に形成されたＸ軸方向に長尺な線路状電極であり、下側ＲＦ容量電極３Ａ，３ＢのＹ軸方向の両脇に下側駆動容量電極４Ａ，４Ｂが配置されている。誘電体膜５は五酸化タンタルからなり、下側ＲＦ容量電極３Ａ，３Ｂと下側駆動容量電極４Ａ，４Ｂとを覆うように、支持板２の上面領域に積層されている。下側ＲＦ容量電極３ＡはＲＦ信号の入力端子（または出力端子）に接続され、下側ＲＦ容量電極３ＢはＲＦ信号の出力端子（または入力端子）に接続されている。下側駆動容量電極４Ａ，４Ｂは、信号カット用の抵抗素子を介して駆動ＤＣ電圧端子に接続されている。可動梁６は、信号カット用の抵抗素子を介してグランドＧＮＤに接続している。このため、下側ＲＦ容量電極３Ａ，３Ｂは、それぞれ可動梁６および誘電体膜５の対向する領域とともにＲＦ容量部Ｃ１Ａ，Ｃ１Ｂを構成している。下側駆動容量電極４Ａ，４Ｂは、それぞれ可動梁６および誘電体膜５の対向する領域とともに駆動容量部Ｃ２Ａ，Ｃ２Ｂを構成している。 The lower RF capacitive electrodes 3A and 3B and the lower drive capacitive electrodes 4A and 4B are line-shaped electrodes that are formed on the upper surface of the support plate 2 and are long in the X-axis direction. Lower drive capacitance electrodes 4A and 4B are arranged on both sides of 3B in the Y-axis direction. The dielectric film 5 is made of tantalum pentoxide, and is laminated on the upper surface region of the support plate 2 so as to cover the lower RF capacitive electrodes 3A and 3B and the lower drive capacitive electrodes 4A and 4B. The lower RF capacitive electrode 3A is connected to an RF signal input terminal (or output terminal), and the lower RF capacitive electrode 3B is connected to an RF signal output terminal (or input terminal). The lower drive capacitance electrodes 4A and 4B are connected to a drive DC voltage terminal via a signal cut resistance element. The movable beam 6 is connected to the ground GND via a resistance element for signal cut. For this reason, the lower RF capacitive electrodes 3A and 3B constitute RF capacitive portions C1A and C1B together with regions where the movable beam 6 and the dielectric film 5 face each other. The lower drive capacitance electrodes 4A and 4B constitute drive capacitance portions C2A and C2B together with the opposing regions of the movable beam 6 and the dielectric film 5, respectively.
　駆動容量部Ｃ２Ａ，Ｃ２Ｂは、その静電引力により可動梁６を支持板２側に引き付け、可動梁６を先端（Ｘ軸正方向側の端部）から誘電体膜５に接触させる駆動容量として機能する。駆動ＤＣ電圧が高電圧であるほど、可動梁６と誘電体膜５との接触面積は大きくなる。 The drive capacitors C2A and C2B serve as drive capacitors that attract the movable beam 6 to the support plate 2 side by the electrostatic attractive force and bring the movable beam 6 into contact with the dielectric film 5 from the tip (end on the X axis positive direction side). Function. The higher the driving DC voltage, the larger the contact area between the movable beam 6 and the dielectric film 5.
　ＲＦ容量部Ｃ１Ａ，Ｃ１Ｂは、数百MHz～数GHzの高周波回路の中で使用され、可動梁６と誘電体膜５との接触面積に応じて容量の大きさが変化するＲＦ容量として機能する。 The RF capacitors C1A and C1B are used in a high-frequency circuit of several hundred MHz to several GHz, and function as RF capacitors whose capacitance changes depending on the contact area between the movable beam 6 and the dielectric film 5. .
　なお、駆動容量部Ｃ２Ａ，Ｃ２Ｂは駆動ＤＣ電圧端子とグランドＧＮＤとの間に並列接続されるため、両者を直列接続する構成に比べて単位面積当たりの静電引力が大きく、両者を直列接続する場合よりも電極面積の低減に有利である。一方、ＲＦ容量部Ｃ１Ａ，Ｃ１ＢはＲＦ信号の入力端子と出力端子との間に直列接続されるため、両者を並列接続する構成に比べて単位面積当たりの静電引力が小さく、両者を並列接続する場合よりもＲＦ信号による可動梁６の変形（セルフアクチエーション）の抑制に有利である。 Since the drive capacitors C2A and C2B are connected in parallel between the drive DC voltage terminal and the ground GND, the electrostatic attraction per unit area is larger than the configuration in which the drive capacitors C2A and C2B are connected in series. This is more advantageous than the case in reducing the electrode area. On the other hand, since the RF capacitors C1A and C1B are connected in series between the RF signal input terminal and the output terminal, the electrostatic attraction per unit area is smaller than the configuration in which both are connected in parallel, and the two are connected in parallel. This is more advantageous for suppressing the deformation (self-actuation) of the movable beam 6 due to the RF signal than the case of doing so.
　図４（Ａ）は、可変容量装置１の駆動回路１１の構成例を説明する図である。
　駆動回路１１は、駆動ＤＣ電圧制御回路１２と、容量検出用交流信号源１３と、増幅回路１４と、整流回路１５と、比較器１６とを備える。駆動ＤＣ電圧制御回路１２は、駆動ＤＣ電圧を出力する。容量検出用交流信号源１３は、約１０ＭＨｚの容量検出用ＡＣ信号を駆動ＤＣ電圧に重畳する。この重畳信号は、可変容量装置１の駆動容量部Ｃ２Ａ，Ｃ２Ｂを含んで構成される容量回路に印加される。この容量回路は、直流バイパス用の抵抗Ｒ２と参照容量部Ｃ４からなる並列回路と、可変容量装置１の駆動容量部Ｃ２Ａ，Ｃ２Ｂからなる並列回路とが、直列に接続された構成である。重畳信号のＤＣ成分によって駆動容量部Ｃ２Ａ，Ｃ２Ｂの容量値が定まり、可変容量装置１における可動梁６の変形量が定まる。重畳信号のＡＣ成分は、駆動容量部Ｃ２Ａ，Ｃ２Ｂの合成容量の容量値と参照容量部Ｃ４の容量値との容量比に応じた振幅として増幅回路１４に出力される。増幅回路１４は容量回路からのＡＣ出力を増幅し、整流回路１５は増幅回路１４からのＡＣ出力を整流し、駆動容量部Ｃ２Ａ，Ｃ２Ｂの合成容量を反映した電圧レベルの検出信号（モニター信号）とする。比較器１６は、駆動容量部Ｃ２Ａ，Ｃ２Ｂの容量設定値を指示するための外部入力信号が入力され、検出信号と外部入力信号との電圧レベルを比較して、ＬＯＷレベルまたはＨＩＧＨレベルに切り替わる出力電圧を出力する。駆動ＤＣ電圧制御回路１２は、比較器１６の出力電圧に応じて駆動ＤＣ電圧を増減し出力する。この駆動回路１１では、外部入力信号に指示された容量設定値に駆動容量部Ｃ２Ａ，Ｃ２Ｂの合成容量が調整されるため、セルフアクチエーションや外乱の影響をほとんど受けることなく、駆動容量部Ｃ２Ａ，Ｃ２Ｂの容量値が安定に設定される。 FIG. 4A is a diagram illustrating a configuration example of the drive circuit 11 of the variable capacitance device 1.
The drive circuit 11 includes a drive DC voltage control circuit 12, a capacitance detection AC signal source 13, an amplifier circuit 14, a rectifier circuit 15, and a comparator 16. The drive DC voltage control circuit 12 outputs a drive DC voltage. The capacitance detection AC signal source 13 superimposes a capacitance detection AC signal of about 10 MHz on the driving DC voltage. This superimposed signal is applied to a capacitance circuit including the drive capacitance units C2A and C2B of the variable capacitance device 1. This capacitor circuit has a configuration in which a parallel circuit composed of a DC bypass resistor R2 and a reference capacitor unit C4 and a parallel circuit composed of drive capacitor units C2A and C2B of the variable capacitor device 1 are connected in series. The capacitance values of the drive capacitance units C2A and C2B are determined by the DC component of the superimposed signal, and the deformation amount of the movable beam 6 in the variable capacitance device 1 is determined. The AC component of the superimposed signal is output to the amplifier circuit 14 as an amplitude corresponding to the capacitance ratio between the capacitance value of the combined capacitance of the drive capacitance units C2A and C2B and the capacitance value of the reference capacitance unit C4. The amplifier circuit 14 amplifies the AC output from the capacitor circuit, and the rectifier circuit 15 rectifies the AC output from the amplifier circuit 14, and a voltage level detection signal (monitor signal) reflecting the combined capacitance of the drive capacitor units C2A and C2B. And The comparator 16 receives an external input signal for instructing the capacitance setting values of the drive capacitor units C2A and C2B, compares the voltage level of the detection signal and the external input signal, and outputs to switch to the LOW level or the HIGH level. Output voltage. The drive DC voltage control circuit 12 increases or decreases the drive DC voltage according to the output voltage of the comparator 16 and outputs it. In this drive circuit 11, since the combined capacitance of the drive capacitance units C2A and C2B is adjusted to the capacitance setting value designated by the external input signal, the drive capacitance units C2A, C2A, C2A, The capacitance value of C2B is set stably.
　このように駆動容量部Ｃ２Ａ，Ｃ２Ｂをフィードバック制御する構成とするとともに、上述のようにＲＦ容量部Ｃ１Ａ，Ｃ１Ｂを直列接続する構成としているため、この可変容量装置１ではセルフアクチエーションの影響を極めて小さくでき、可動梁６の主軸方向のバネ定数を低減して駆動ＤＣ電圧を低電圧化することが可能である。 In this way, the drive capacitance units C2A and C2B are configured to perform feedback control, and the RF capacitance units C1A and C1B are configured to be connected in series as described above. Therefore, in the variable capacitance device 1, the influence of self-activation is extremely high. The drive DC voltage can be lowered by reducing the spring constant of the movable beam 6 in the principal axis direction.
　図４（Ｂ）は、駆動回路１１により駆動する可変容量装置１の駆動ＤＣ電圧－ＲＦ容量特性を例示する図である。図中には、本実施形態の構成における駆動ＤＣ電圧－ＲＦ容量特性を実線で表示し、可動部６Ａの厚みを一様にした比較構成における駆動ＤＣ電圧－ＲＦ容量特性を点線で表示している。 FIG. 4B is a diagram illustrating drive DC voltage-RF capacitance characteristics of the variable capacitance device 1 driven by the drive circuit 11. In the figure, the driving DC voltage-RF capacitance characteristic in the configuration of the present embodiment is displayed by a solid line, and the driving DC voltage-RF capacitance characteristic in a comparative configuration in which the thickness of the movable portion 6A is uniform is displayed by a dotted line. Yes.
　本実施形態の構成および比較構成ともに、駆動ＤＣ電圧がゼロから第１の閾値までの範囲では、可動梁６は誘電体膜５から離間した状態であり、駆動ＤＣ電圧が変化してもＲＦ容量は殆ど変化しない。そして、駆動ＤＣ電圧が第１の閾値となると、可動梁６の先端が誘電体膜５に接触する状態になり、ＲＦ容量が大幅に増大する。駆動ＤＣ電圧が第１の閾値から第２の閾値までの範囲では、可動梁６と誘電体膜５との接触面積が駆動ＤＣ電圧に応じて線形変化し、駆動ＤＣ電圧の増加につれて接触面積が増大し、これによりＲＦ容量が増加する。駆動ＤＣ電圧が第２の閾値となると、可動梁６と誘電体膜５との接触面積が最大化した状態になり、ＲＦ容量も最大化する。駆動ＤＣ電圧が第２の閾値を超えて大きくなっても、可動梁６と誘電体膜５との接触面積は最大化した状態のままであり、ＲＦ容量は殆ど変化しなくなる。 In both the configuration of this embodiment and the comparative configuration, the movable beam 6 is in a state of being separated from the dielectric film 5 in the range where the driving DC voltage is from zero to the first threshold value, and even if the driving DC voltage changes, the RF capacitance Hardly changes. When the driving DC voltage becomes the first threshold value, the tip of the movable beam 6 comes into contact with the dielectric film 5, and the RF capacitance is greatly increased. When the drive DC voltage is in the range from the first threshold value to the second threshold value, the contact area between the movable beam 6 and the dielectric film 5 changes linearly according to the drive DC voltage, and the contact area increases as the drive DC voltage increases. Increase, which increases the RF capacity. When the drive DC voltage becomes the second threshold value, the contact area between the movable beam 6 and the dielectric film 5 is maximized, and the RF capacity is also maximized. Even if the drive DC voltage increases beyond the second threshold, the contact area between the movable beam 6 and the dielectric film 5 remains maximized, and the RF capacitance hardly changes.
　本実施形態の構成では、前述のように可動梁６がＸ軸方向に柔らかい構成であり、可動梁６におけるＸ軸方向のバネ定数が小さいので、比較構成に比べて、可動梁６の先端が誘電体膜５に接触する駆動ＤＣ電圧の第１の閾値、および、可動梁６と誘電体膜５との接触面積が最大化する駆動ＤＣ電圧の第２の閾値が小さい。したがって、駆動ＤＣ電圧を低電圧化しても可動梁６を適正に変形させることが可能になる。そして本実施形態の構成では、可動梁６がＹ軸方向に硬い構成であるので、図２（Ｃ）に示したようなＹ軸方向（可動梁６の幅方向）での撓みを極めて小さくすることができ、駆動容量部Ｃ２Ａ，Ｃ２Ｂの容量変化とＲＦ容量部Ｃ１Ａ，Ｃ１Ｂの容量変化との相関性にずれが発生することなく、駆動ＤＣ電圧を低電圧化することができる。 In the configuration of the present embodiment, the movable beam 6 is soft in the X-axis direction as described above, and the spring constant in the X-axis direction of the movable beam 6 is small, so that the tip of the movable beam 6 is smaller than the comparative configuration. The first threshold value of the driving DC voltage that contacts the dielectric film 5 and the second threshold value of the driving DC voltage that maximizes the contact area between the movable beam 6 and the dielectric film 5 are small. Therefore, the movable beam 6 can be appropriately deformed even when the driving DC voltage is lowered. In the configuration of the present embodiment, since the movable beam 6 is hard in the Y-axis direction, the deflection in the Y-axis direction (the width direction of the movable beam 6) as shown in FIG. Therefore, the drive DC voltage can be lowered without causing a deviation in the correlation between the capacitance change of the drive capacitor portions C2A and C2B and the capacitance change of the RF capacitor portions C1A and C1B.
　次に、本実施形態に係る可変容量装置１の製造工程について説明する。
　図５は、可変容量装置１の製造工程における可動梁６の加工過程の一例を示す模式図である。 Next, the manufacturing process of the variable capacitance device 1 according to this embodiment will be described.
FIG. 5 is a schematic diagram illustrating an example of a process of processing the movable beam 6 in the manufacturing process of the variable capacitance device 1.
　以下で説明する可動梁６の加工過程の前には、複数の可変容量装置１を一度に製造するために、大面積のウェハ状の低抵抗シリコン母基板３６およびガラス母基板３２を用意し、ガラス母基板３２に各可変容量装置１の下側ＲＦ容量電極３Ａ，３Ｂ、下側駆動容量電極４Ａ，４Ｂおよび誘電体膜５を形成し、低抵抗シリコン母基板３６に支持部６Ｃとなる突出部を形成し、両者を陽極接合法または清浄化接合法により接合しておく。 Before processing the movable beam 6 described below, in order to manufacture a plurality of variable capacitance devices 1 at a time, a large-area wafer-like low-resistance silicon mother substrate 36 and a glass mother substrate 32 are prepared. Lower RF capacitive electrodes 3A and 3B, lower drive capacitive electrodes 4A and 4B, and dielectric film 5 are formed on glass mother substrate 32, and projecting as support portion 6C on low-resistance silicon mother substrate 36. A part is formed, and both are bonded by an anodic bonding method or a cleaning bonding method.
　可動梁６の加工過程では、まず、低抵抗シリコン母基板３６の上面に、線路状稜部６Ａ１と同じパターン形状で第１マスク層３７を形成する（Ｓ１）。第１マスク層３７は例えばＡｌやＳｉＯ２からなり、後の２次エッチング工程において、エッチャントによるシリコンとの選択性が得られる材料を採用する。 In the process of processing the movable beam 6, first, the first mask layer 37 is formed on the upper surface of the low resistance silicon mother substrate 36 in the same pattern shape as the line-shaped ridge 6A1 (S1). The first mask layer 37 is made of, for example, Al or SiO 2 , and adopts a material capable of obtaining selectivity with silicon by an etchant in a subsequent secondary etching process.
　次に、低抵抗シリコン母基板３６および第１マスク層３７の上面に、可動梁６と同じパターン形状で第２マスク層３８を形成する（Ｓ２）。第２マスク層３８は例えばポジレジスト材料からなり、後の１次エッチング工程において、エッチャントによるシリコンとの選択性が得られる材料を採用する。 Next, a second mask layer 38 is formed in the same pattern shape as the movable beam 6 on the upper surfaces of the low-resistance silicon mother substrate 36 and the first mask layer 37 (S2). The second mask layer 38 is made of, for example, a positive resist material, and a material capable of obtaining selectivity with silicon by an etchant is used in a subsequent primary etching process.
　次に、低抵抗シリコン母基板３６をドライエッチングする１次エッチング工程を実施する（Ｓ３）。この工程により第２マスク層３８に覆われる領域を残して低抵抗シリコン母基板３６を部分除去し、支持部６Ｃと連結部６Ｂと可動部６Ａとからなる複数の可動梁６を形成する。 Next, a primary etching process for dry etching the low resistance silicon mother substrate 36 is performed (S3). By this process, the low resistance silicon mother substrate 36 is partially removed leaving a region covered with the second mask layer 38, and a plurality of movable beams 6 including the support portion 6C, the connecting portion 6B, and the movable portion 6A are formed.
　次に、第２マスク層３８をＯ２アッシングにより除去する（Ｓ４）。 Next, the second mask layer 38 is removed by O 2 ashing (S4).
　次に、可動部６Ａをドライエッチングする２次エッチング工程を実施する（Ｓ５）。この工程により第１マスク層３７に覆われる線路状稜部６Ａ１を残して可動部６Ａを一定厚み分除去し、線路状溝部６Ａ２を形成する。 Next, a secondary etching step for dry etching the movable portion 6A is performed (S5). By this step, the movable portion 6A is removed by a certain thickness while leaving the line-shaped ridge 6A1 covered by the first mask layer 37, and the line-shaped groove 6A2 is formed.
　次に、第１マスク層３７をウェットエッチングにより除去する（Ｓ６）。以上の各工程により可動梁６を成形した後、ガラス母基板３２のダイシングにより支持板２を切り出して複数の可変容量装置１を製造する。 Next, the first mask layer 37 is removed by wet etching (S6). After forming the movable beam 6 by the above steps, the support plate 2 is cut out by dicing the glass mother substrate 32 to manufacture a plurality of variable capacitance devices 1.
　以上の製造工程を経て本実施形態の可変容量装置１は製造されるが、可動梁６における線路状稜部６Ａ１と線路状溝部６Ａ２との形成に低抵抗シリコン基板のドライエッチングを用いることで、線幅加工精度を改善でき、1um程度の微細な加工が可能となる。なお、ドライエッチングに替えてウェットエッチングを用いてもよく、その場合、ドライエッチングに比べて低コストでの加工が可能となる。 The variable capacitance device 1 of the present embodiment is manufactured through the above manufacturing process, but by using dry etching of a low resistance silicon substrate for forming the line-shaped ridge 6A1 and the line-shaped groove 6A2 in the movable beam 6, Line width processing accuracy can be improved, and fine processing of about 1um is possible. Note that wet etching may be used instead of dry etching, and in this case, processing can be performed at a lower cost than dry etching.
《第２の実施形態》
　図６（Ａ）は、本発明の第２の実施形態に係る可変容量装置４１のＸ－Ｙ面平面図である。図６（Ｂ）は、可変容量装置４１のＸ－Ｚ面断面図である。図６（Ｃ）は、可変容量装置４１のＹ－Ｚ面断面図である。 << Second Embodiment >>
FIG. 6A is an XY plane plan view of the variable capacitance device 41 according to the second embodiment of the present invention. FIG. 6B is a cross-sectional view of the variable capacitance device 41 taken along the XZ plane. FIG. 6C is a YZ plane cross-sectional view of the variable capacitance device 41.
　本実施形態の可変容量装置４１は、可動梁４６を備える。可動梁４６は、可動部４６Ａと梁状部４６Ｂと支持部４６Ｃとを備える。そして、可動部４６Ａの上面（Ｚ軸正方向の主面）には、線路状稜部４６Ａ１と線路状溝部４６Ａ２とがＸ軸方向に交互に配列され、それぞれがＹ軸方向に延設されている。この可動部４６Ａは一体の低抵抗シリコン基板から形成されているのではなく、低抵抗シリコンによる平板層４７Ａと、平板層４７Ａの上面に積層形成された付加層４７Ｂとから構成されている。付加層４７Ｂは、Ｙ軸方向に延び、Ｘ軸方向に所定の間隔で配列されるように形成されている複数の溝を有する。なお、付加層４７Ｂについてはどのような構成材料であっても良いが、ヤング率の大きな構成材料であると好適であり、金属膜であればタングステン膜やモリブデン膜、プラチナ膜などを、絶縁膜であればＳｉＯ２膜などを採用することができる。また付加層４７Ｂのパターニングには、リフトオフ法やメッキ法などの工法を採用することができる。 The variable capacitance device 41 of this embodiment includes a movable beam 46. The movable beam 46 includes a movable part 46A, a beam-like part 46B, and a support part 46C. Then, on the upper surface (main surface in the positive Z-axis direction) of the movable portion 46A, the line-shaped ridge portions 46A1 and the line-shaped groove portions 46A2 are alternately arranged in the X-axis direction, and each extend in the Y-axis direction. Yes. The movable portion 46A is not formed of an integral low-resistance silicon substrate, but is composed of a flat layer 47A made of low-resistance silicon and an additional layer 47B laminated on the upper surface of the flat layer 47A. The additional layer 47B has a plurality of grooves that extend in the Y-axis direction and are arranged at predetermined intervals in the X-axis direction. Any material may be used for the additional layer 47B, but a material having a large Young's modulus is preferable. For a metal film, a tungsten film, a molybdenum film, a platinum film, or the like is used as an insulating film. If so, a SiO 2 film or the like can be employed. Further, for the patterning of the additional layer 47B, a method such as a lift-off method or a plating method can be employed.
　本実施形態の可変容量装置４１は、前述の第１の実施形態のように溝切り加工により可動梁の構成部材を部分除去する構成に比べて、平板層４７Ａの上面に付加層４７Ｂを付加するのみであるため可動梁自体に構造的な欠陥が生じ難く、また、溝切り加工が困難な材料であっても構成材料として採用することができる。そのため、可動梁の主構成材料として、金や銅などの金属材料、ＳｉＯ２、ＳｉＮ、ｐｏｌｙ－Ｓｉ、多結晶ダイヤモンドなどの多様な材料を用いることが可能になる。 The variable capacitance device 41 of this embodiment adds an additional layer 47B to the upper surface of the flat plate layer 47A, compared to a configuration in which the constituent members of the movable beam are partially removed by grooving as in the first embodiment. Therefore, it is difficult to cause structural defects in the movable beam itself, and even a material that is difficult to grooving can be adopted as a constituent material. Therefore, various materials such as metal materials such as gold and copper, SiO 2 , SiN, poly-Si, and polycrystalline diamond can be used as the main constituent material of the movable beam.
《第３の実施形態》
　図７（Ａ）は、本発明の第３の実施形態に係る可変容量装置５１のＸ－Ｚ面断面図である。図７（Ｂ）は、可変容量装置５１のＹ－Ｚ面断面図である。本実施形態の可変容量装置５１は、絶縁性材料からなる可動梁５６を備える。可動梁５６は、可動部５６Ａと梁状部５６Ｂと支持部５６Ｃとを備える。可動梁５６は、前述の第１の実施形態の可動梁６と同じように、線路状稜部と線路状溝部とを有する。そして、本実施形態の可変容量装置５１は、可動梁５６の下面にパターン形成した上側ＲＦ容量電極５７Ａ及び上側駆動容量電極５７Ｂ，５７Ｃを備える構成である。 << Third Embodiment >>
FIG. 7A is an XZ plane cross-sectional view of the variable capacitance device 51 according to the third embodiment of the present invention. FIG. 7B is a YZ plane cross-sectional view of the variable capacitance device 51. The variable capacitance device 51 of this embodiment includes a movable beam 56 made of an insulating material. The movable beam 56 includes a movable portion 56A, a beam-shaped portion 56B, and a support portion 56C. The movable beam 56 has a line-shaped ridge portion and a line-shaped groove portion, like the movable beam 6 of the first embodiment described above. The variable capacitance device 51 of the present embodiment is configured to include an upper RF capacitance electrode 57A and upper drive capacitance electrodes 57B and 57C that are patterned on the lower surface of the movable beam 56.
　上側ＲＦ容量電極５７Ａと上側駆動容量電極５７Ｂ，５７Ｃとは、それぞれ可動梁５６の下面に形成されたＸ軸方向に長尺な線路状電極である。上側ＲＦ容量電極５７Ａは、下側ＲＦ容量電極３Ａ，３Ｂに対向するように設けられている。上側駆動容量電極５７Ｂ，５７Ｃは、それぞれ下側駆動容量電極４Ａ，４Ｂに対向するように設けられている。上側ＲＦ容量電極５７Ａは、下側ＲＦ容量電極３Ａ，３Ｂおよび誘電体膜５の対向する領域とともにＲＦ容量部Ｃ１Ａ，Ｃ１Ｂを構成している。上側駆動容量電極５７Ｂ，５７Ｃは、それぞれ下側駆動容量電極４Ａ，４Ｂおよび誘電体膜５の対向する領域とともに駆動容量部Ｃ２Ａ，Ｃ２Ｂを構成している。 The upper RF capacitive electrode 57A and the upper drive capacitive electrodes 57B and 57C are line-shaped electrodes that are formed on the lower surface of the movable beam 56 and are long in the X-axis direction. The upper RF capacitive electrode 57A is provided so as to face the lower RF capacitive electrodes 3A and 3B. The upper drive capacitance electrodes 57B and 57C are provided so as to face the lower drive capacitance electrodes 4A and 4B, respectively. The upper RF capacitive electrode 57A, together with the opposing regions of the lower RF capacitive electrodes 3A and 3B and the dielectric film 5, constitutes RF capacitive portions C1A and C1B. The upper drive capacitance electrodes 57B and 57C constitute drive capacitance portions C2A and C2B together with the opposing regions of the lower drive capacitance electrodes 4A and 4B and the dielectric film 5, respectively.
　この構成では、ＲＦ容量部Ｃ１Ａ，Ｃ１Ｂと、駆動容量部Ｃ２Ａ，Ｃ２Ｂとを電気的に分離することができ、前述の実施形態のような導電性材料の可動梁を用いる場合に必要であった信号カット用の素子が駆動回路に必須の構成ではなくなり、駆動回路の回路構成を簡易化できる。 In this configuration, the RF capacitors C1A and C1B and the drive capacitors C2A and C2B can be electrically separated, which is necessary when using a movable beam of conductive material as in the above-described embodiment. The element for signal cut is not an essential component for the drive circuit, and the circuit configuration of the drive circuit can be simplified.
　以上の各実施形態では、可動梁を片持ち梁構造として説明したが、可動梁は両持ち梁構造であっても片持ち梁構造であってもよく、いずれにしても線路状溝部を適切な形状で設けることにより、本発明は好適に実施できる。また、線路状溝部の断面形状を矩形状として説明したが、断面形状についても様々な形状が採用できる。本発明は実施形態の記載に制限されるものではなく、本発明の範囲は、特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図されるものである。 In each of the above embodiments, the movable beam has been described as a cantilever beam structure. However, the movable beam may be a double-sided beam structure or a cantilever structure. By providing the shape, the present invention can be suitably implemented. Moreover, although the cross-sectional shape of the line-shaped groove portion has been described as a rectangular shape, various shapes can be adopted as the cross-sectional shape. The present invention is not limited to the description of the embodiments, and the scope of the present invention is defined by the scope of the claims, and includes all modifications within the meaning and scope equivalent to the scope of the claims. Is intended.
　１，４１，５１…可変容量装置
　２…支持板
　３Ａ，３Ｂ…下側ＲＦ容量電極
　４Ａ，４Ｂ…下側駆動容量電極
　５…誘電体膜
　６，４６，５６…可動梁
　６Ａ，４６Ａ，５６Ａ…可動部
　６Ａ１，４６Ａ１…線路状稜部
　６Ａ２，４６Ａ２…線路状溝部
　６Ｂ，４６Ｂ，５６Ｂ…連結部
　６Ｃ，４６Ｃ，５６Ｃ…支持部
　１１…駆動回路
　４７Ａ…平板層
　４７Ｂ…付加層
　５７Ａ…上側ＲＦ容量電極
　５７Ｂ，５７Ｃ…上側駆動容量電極
　Ｃ１Ａ，Ｃ１Ｂ…ＲＦ容量部
　Ｃ２Ａ，Ｃ２Ｂ…駆動容量部
　Ｃ４…参照容量部 DESCRIPTION OF SYMBOLS 1,41,51 ... Variable capacitance apparatus 2 ... Support plate 3A, 3B ... Lower RF capacitive electrode 4A, 4B ... Lower drive capacitive electrode 5 ... Dielectric film 6, 46, 56 ... Movable beams 6A, 46A, 56A ... Movable part 6A1, 46A1 ... line-like ridge part 6A2, 46A2 ... line- like groove part 6B, 46B, 56B ... connection part 6C, 46C, 56C ... support part 11 ... drive circuit 47A ... flat plate layer 47B ... additional layer 57A ... upper RF capacitance Electrodes 57B, 57C ... Upper drive capacitor electrodes C1A, C1B ... RF capacitors C2A, C2B ... Drive capacitors C4 ... Reference capacitor

Claims (5)

  1. 　支持板と、
    　前記支持板の主面に平行に支持され、導電性材料からなる可動梁と、
    　前記可動梁に対向するように前記支持板に設けられる駆動容量電極と、前記可動梁と前記駆動容量電極との間に形成される誘電体膜とからなり、前記可動梁と前記駆動容量電極との間に生じる駆動容量に基づいて前記可動梁を変形させる駆動容量部と、
    　前記可動梁に対向するように前記支持板に設けられるＲＦ容量電極と、前記可動梁と前記ＲＦ容量電極との間に形成される誘電体膜とからなり、前記可動梁と前記ＲＦ容量電極との間に生じるＲＦ容量を介してＲＦ信号を伝搬させるＲＦ容量部と、
    　を備え、
    　前記可動梁は、前記可動梁の主面に垂直な厚み方向の寸法が局所的に小さく前記可動梁における主軸方向および厚み方向と略垂直な幅方向に線路状に延設される線路状溝部を備え、複数の前記線路状溝部を間隔を隔てて前記主軸方向に配列させた構成である、可変容量装置。     A support plate;
    A movable beam supported in parallel to the main surface of the support plate and made of a conductive material;
    A driving capacitor electrode provided on the support plate so as to face the movable beam; and a dielectric film formed between the movable beam and the driving capacitor electrode. The movable beam and the driving capacitor electrode; A driving capacity unit for deforming the movable beam based on a driving capacity generated between
    An RF capacitive electrode provided on the support plate so as to face the movable beam, and a dielectric film formed between the movable beam and the RF capacitive electrode, the movable beam, the RF capacitive electrode, An RF capacitor for propagating an RF signal through an RF capacitor generated between
    With
    The movable beam has a line-shaped groove portion extending in a line shape in a width direction substantially perpendicular to the principal axis direction and the thickness direction of the movable beam, and the dimension in the thickness direction perpendicular to the main surface of the movable beam is locally small. And a variable capacitance device having a configuration in which a plurality of the line-shaped groove portions are arranged in the main axis direction at intervals.
  2. 　支持板と、
    　前記支持板の主面に平行に支持される可動梁と、
    　前記可動梁と前記支持板とに互いに対向して設けられる一対の駆動容量電極と、前記一対の駆動容量電極の少なくとも一方に積層される誘電体膜とからなり、前記一対の駆動容量電極の間に生じる駆動容量に基づいて前記可動梁を変形させる駆動容量部と、
    　前記可動梁と前記支持板とに互いに対向して設けられる一対のＲＦ容量電極と、前記一対のＲＦ容量電極の少なくとも一方に積層される誘電体膜とからなり、前記一対のＲＦ容量電極の間に生じるＲＦ容量を介してＲＦ信号を伝搬させるＲＦ容量部と、
    　を備え、
    　前記可動梁は、前記可動梁の主面に垂直な厚み方向の寸法が局所的に小さく前記可動梁における主軸方向および厚み方向と略垂直な幅方向に線路状に延設される線路状溝部を備え、複数の前記線路状溝部を間隔を隔てて前記主軸方向に配列させた構成である、可変容量装置。     A support plate;
    A movable beam supported parallel to the main surface of the support plate;
    A pair of drive capacitance electrodes provided opposite to each other on the movable beam and the support plate, and a dielectric film laminated on at least one of the pair of drive capacitance electrodes, and between the pair of drive capacitance electrodes A drive capacity unit for deforming the movable beam based on a drive capacity generated in
    A pair of RF capacitive electrodes provided opposite to each other on the movable beam and the support plate, and a dielectric film laminated on at least one of the pair of RF capacitive electrodes, between the pair of RF capacitive electrodes An RF capacitor for propagating an RF signal through an RF capacitor generated in
    With
    The movable beam has a line-shaped groove portion extending in a line shape in a width direction substantially perpendicular to the principal axis direction and the thickness direction of the movable beam, and the dimension in the thickness direction perpendicular to the main surface of the movable beam is locally small. And a variable capacitance device having a configuration in which a plurality of the line-shaped groove portions are arranged in the main axis direction at intervals.
  3. 　前記駆動容量に応じて変化する検出電圧を検出し、その検出電圧が所望値に近づくように駆動ＤＣ電圧を制御する駆動回路をさらに備える、請求項１または２に記載の可変容量装置。 The variable capacitance device according to claim 1 or 2, further comprising a drive circuit that detects a detection voltage that changes in accordance with the drive capacitance and controls a drive DC voltage so that the detection voltage approaches a desired value.
  4. 　前記可動梁は、構成材料の部分的除去により前記線路状溝部が形成された構成である、請求項１～３のいずれかに記載の可変容量装置。 The variable capacitance device according to any one of claims 1 to 3, wherein the movable beam has a configuration in which the line-shaped groove is formed by partial removal of a constituent material.
  5. 　前記可動梁は、構成材料の部分的付加により前記線路状溝部が形成された構成である、請求項１～３のいずれかに記載の可変容量装置。 4. The variable capacitance device according to claim 1, wherein the movable beam has a configuration in which the line-shaped groove is formed by partial addition of a constituent material.
PCT/JP2011/063101 2010-06-17 2011-06-08 Variable capacitance device WO2011158708A1 (en)

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Publication number Priority date Publication date Assignee Title
WO2014064688A1 (en) * 2012-10-22 2014-05-01 Technion Research & Development Foundation Ltd. Electromechanical battery
GB2508181A (en) * 2012-11-22 2014-05-28 Technion Res & Dev Foundation Energy storage capacitor which maintains voltage during discharge
EP3878804A1 (en) * 2015-06-15 2021-09-15 FRAUNHOFER-GESELLSCHAFT zur Förderung der angewandten Forschung e.V. Mems transducer for interacting with a volume flow of a fluid and method of manufacturing the same

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JP2006175557A (en) * 2004-12-22 2006-07-06 Nippon Telegr & Teleph Corp <Ntt> Microstructure
JP2006294866A (en) * 2005-04-11 2006-10-26 Toshiba Corp Semiconductor device
JP2007324336A (en) * 2006-05-31 2007-12-13 Toshiba Corp Variable capacity device and cellular phone

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JP2006175557A (en) * 2004-12-22 2006-07-06 Nippon Telegr & Teleph Corp <Ntt> Microstructure
JP2006294866A (en) * 2005-04-11 2006-10-26 Toshiba Corp Semiconductor device
JP2007324336A (en) * 2006-05-31 2007-12-13 Toshiba Corp Variable capacity device and cellular phone

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014064688A1 (en) * 2012-10-22 2014-05-01 Technion Research & Development Foundation Ltd. Electromechanical battery
GB2508181A (en) * 2012-11-22 2014-05-28 Technion Res & Dev Foundation Energy storage capacitor which maintains voltage during discharge
EP3878804A1 (en) * 2015-06-15 2021-09-15 FRAUNHOFER-GESELLSCHAFT zur Förderung der angewandten Forschung e.V. Mems transducer for interacting with a volume flow of a fluid and method of manufacturing the same

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