JP2005340536A - Variable capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable capacitor whose variance is less against a designed capacitance value and can realize a stable capacitance value even if vibrations or noises or the like are given from the outside. <P>SOLUTION: A lower electrode 2 having a wide area is formed on a substrate 1, and an upper electrode 4 having a wide area is arranged opposite to the lower electrode 2, while an insulative support member 3 is arranged between the upper and lower electrodes 4 and 2 to divide the upper electrode 4 into a plurality of movable areas, and to displace them to the side of the lower electrode 2. In such the variable capacitor, the upper electrode 4 is divided into a plurality of movable areas and they are supported by the support member 3, so that the upper electrode 4 can be stably displaced to the side of the lower electrode 2 in the respective movable areas. Therefore, the variable capacitor has less variance against a designed capacitance value, and can realize a stable capacitance value even if vibrations or noises or the like are given from the outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable capacitor, and more particularly to an electrostatic drive type variable capacitor.

  In recent years, variable capacitors capable of changing the capacitance value have been widely used as capacitors in various electric devices, communication systems, portable communication terminals, and the like. The capacitance of the capacitor is a capacitance value according to the dielectric constant of the dielectric material between the two electrodes (for example, the upper electrode and the lower electrode), the area of the portion where the two electrodes face each other, and the distance between the two electrodes . Therefore, as a method of changing the capacitance value of the variable capacitor, a method of changing the dielectric constant of the dielectric material between the two electrodes, for example, the area of the location where the capacitance value is formed or the distance between the two electrodes, etc. There is known a method of changing the shape of a member constituting a variable capacitor.

As a method of changing the shape of the member constituting the variable capacitor, there is a method of changing the distance between the two electrodes using electrostatic attraction generated by applying a voltage to the two electrodes. Hereinafter, a variable capacitor whose capacitance value is changed by this method is referred to as an electrostatic drive type variable capacitor. FIGS. 8A and 8B are sectional views of general electrostatic drive type variable capacitors (see, for example, Patent Document 1). In FIG. 8, 101 is a substrate, and 102 is a lower electrode. 104 are upper electrodes. The lower electrode 102 is formed on the substrate 101, and the upper electrode 104 from the portion where the lower electrode 102 is not formed on the substrate 101 is formed into a cantilever shape in FIG. ) Is formed in the shape of a doubly supported beam (membrane). Here, the upper electrode 104 is formed so that both of them are parallel to each other at a portion facing the lower electrode 102, and the upper electrode 104 is movable. In such a variable capacitor, the upper electrode 104 is connected to the lower electrode 102 side by electrostatic attraction generated between the upper electrode 104 and the lower electrode 102 by applying a voltage between the upper electrode 104 and the lower electrode 102. As a result, the distance between the upper electrode 104 and the lower electrode 102 changes and the capacitance changes.
JP 2000-208944 JP

  However, in the variable capacitor shown in FIG. 8, when the upper electrode 104 having a large area is used, the thin upper electrode 104 that is movable in a portion facing the lower electrode 102 is formed to have a uniform thickness over a large area. Therefore, since the thickness of the upper electrode 104 is not uniform, the upper electrode 104 is distorted upward or downward, and it is difficult to make the shape parallel to the lower electrode 102. Therefore, there is a problem that the distance between the upper electrode 104 and the lower electrode 102 varies within the variable capacitor, and the capacitance value of the variable capacitor varies with respect to a desired capacitance value.

  Also, if the upper electrode 104 having a large area is displaced toward the lower electrode 102, the displacement of the upper electrode 104 varies in the plane of the upper electrode 104, so that even if the same voltage is applied, different capacitance values are obtained, and the desired capacitance is accurately obtained. There was a problem that the value could not be obtained.

  Furthermore, there is a problem that the upper electrode 104 vibrates due to external vibration or electrical noise, and the capacitance value of the variable capacitor is not stable.

  The present invention has been devised to solve the above-described problems in the prior art, and an object of the present invention is to reduce variation with respect to a desired capacitance value in an electrostatic drive type variable capacitor. Another object of the present invention is to provide a variable capacitor capable of realizing a stable capacitance value even in the presence of external vibration or electrical noise.

  In the variable capacitor according to the present invention, a lower electrode having a large area is formed on a substrate, an upper electrode having a large area is disposed so as to face the lower electrode, and between the lower electrode and the upper electrode. An insulating support member is arranged for dividing the upper electrode into a plurality of movable regions and displacing each of the upper electrode toward the lower electrode.

  The variable capacitor of the present invention is characterized in that, in the above configuration, a hole is opened in the movable region of the upper electrode.

  The variable capacitor according to the present invention is characterized in that, in the above configuration, a dielectric is disposed between the lower electrode and the upper electrode of the movable region.

  According to the variable capacitor of the present invention, the lower electrode having a large area is formed on the substrate, the upper electrode having the large area is disposed so as to face the lower electrode, and the lower electrode is interposed between the lower electrode and the upper electrode. Since the insulating support member for displacing the upper electrode into a plurality of movable regions and displacing each of the upper electrode to the lower electrode side is disposed, the upper electrode and the lower electrode in a state where no voltage is applied by the support member, Therefore, the upper electrode having a large area and the lower electrode having a large area can be arranged in parallel over the entire surface, and variations in the designed capacitance value can be suppressed. In addition, since the upper electrode is divided into a plurality of movable regions and each movable region is supported by a support member, the upper electrode can be stably displaced toward the lower electrode in each movable region. Even when the upper electrode of the area is used, a variable capacitor can be obtained that can be accurately displaced to obtain a desired capacitance value. Furthermore, since the upper electrode is divided into a plurality of movable regions and each movable region is supported by a support member, the upper electrode of a large area vibrates greatly due to external vibration or electrical noise. Since it is possible to effectively suppress the vibration of the upper electrode for each movable region, a variable capacitance capacitor can be obtained that can obtain a stable capacitance value that is not affected by external vibration, electrical noise, or the like.

  Further, according to the variable capacitor of the present invention, when the hole is opened in the movable region of the upper electrode, the hole functions as a ventilation hole, so the air resistance for moving the upper electrode is reduced, and the operation is faster. It becomes a variable capacitor that can be used.

  Further, according to the variable capacitor of the present invention, when a dielectric is disposed between the lower electrode and the upper electrode of the movable region, the dielectric has a higher dielectric constant than the atmosphere, and therefore has a larger capacitance. It can be a variable capacitor.

  Hereinafter, the variable capacitor of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a variable capacitor according to the present invention.

  In FIG. 1, 1 is a substrate, 2 is a lower electrode, 3 is a support member for dividing the upper electrode 4 into a plurality of movable regions and displacing them to the lower electrode 2 side, and 4 is an upper electrode.

  The substrate 1 is not particularly limited as long as it is a flat plate made of an insulating material having a strength capable of supporting the lower electrode 2, the support member 3 and the upper electrode 4 formed or arranged on the substrate 1. For example, silicon, glass, quartz , Alumina and other ceramics, resins, etc. are used.

  A lower electrode 2 having a large area is formed on such a substrate 1. The lower electrode 2 is not particularly limited as long as it is a conductive material. For example, copper (Cu), gold (Au), chromium (Cr), titanium (Ti), platinum (Pt), aluminum (Al), silver Even if a single film is formed using a metal material such as (Ag) or nickel (Ni) by a film formation method such as sputtering, vapor deposition, CVD, plating, or printing. Alternatively, a plurality of films made of different components may be stacked.

A support member 3 for dividing the upper electrode 4 into a plurality of movable regions is disposed on the lower electrode 2 between the upper electrode 4 and the upper electrode 4. The support member 3 is not particularly limited as long as it is an insulating material. For example, using a material such as silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), resin, etc., sputtering method, various CVD methods, printing The film may be formed by a method such as a method or a spin coating method and processed into a desired shape. Alternatively, a sheet made of these materials may be processed into a desired shape and disposed on the lower electrode 2.

  Next, FIGS. 2A to 2C are perspective views showing examples of the shape and arrangement of the support member 3, respectively. Here, in FIGS. 2A to 2C, the support member 3 is shown by hatching in order to facilitate understanding of the shape and arrangement of the support member 3.

  In order to divide the upper electrode 4 into a plurality of movable regions, the shape seen from directly above the support member 3 is a lattice shape (example in FIG. 2A), or a plurality of elongated rectangular support members 3 are arranged in the vertical direction. And arranged in a grid-like arrangement with a gap in two directions, ie, the horizontal direction (example in FIG. 2B), and a large number of circular support members 3 regularly arranged (FIG. 2C). Example), and combining these shapes and arrangements. The shape seen from directly above the support member 3 may be a lattice shape, a rectangular shape, a polygonal shape, a shape with dull corners, a circular shape, an elliptical shape, or the like. Further, if the interval between the lattices when the support member 3 is formed in a lattice shape or the interval between the adjacent support members 3 when arranging the plurality of support members 3 is too narrow, the displacement of the upper electrode 4 becomes small and the capacitance changes. If the rate is too small and too wide, each movable region of the upper electrode 4 divided by the support member 3 cannot be stably displaced toward the lower electrode 2 side. As for the height of the support member 3, a desired capacitance value can be obtained without the lower electrode 2 and the upper electrode 4 being in contact with each other, and an electrostatic attractive force capable of displacing the upper electrode 4 toward the lower electrode 2 can be obtained. Thus, it is determined according to the magnitude of the voltage applied between the lower electrode 2 and the upper electrode 4. Further, the cross-sectional shape in the height direction is not limited to the rectangular shape shown in FIG. 1, but may be a trapezoidal shape or a circular shape.

  Thus, by supporting the upper electrode 4 in a plurality of movable regions by the support member 3, the distance between the upper electrode 4 and the lower electrode 2 in a state where no voltage is applied is kept constant, and the upper electrode 4 and the lower electrode 2 are kept constant. Since the electrode 2 can be arranged in parallel, variation with respect to the designed capacitance value can be suppressed.

  Further, since the upper electrode 4 is divided into a plurality of movable regions and supported by the support member 3, the upper electrode 4 can be stably displaced toward the lower electrode 2 in each movable region. Even when the electrode 2 and the upper electrode 4 having a large area are used, it is possible to obtain a capacitance value that changes with a desired change rate with high accuracy. Further, since the lower electrode 2 having a large area and the upper electrode 4 having a large area can be used, a large-capacity variable capacitor can be obtained.

  The upper electrode 4 is disposed in contact with the support member 3 and in parallel with the lower electrode 2. The upper electrode 4 is not particularly limited as long as it is a conductive material. For example, a metal material such as Cu, Au, Cr, Ti, Pt, Al, Ag, or Ni is used to form a sputtering method, a vapor deposition method, or various CVD methods. A single film may be formed by a film forming method such as a method, a plating method, or a printing method, or a plurality of films made of different components may be stacked. Moreover, you may arrange | position on the supporting member 3 using the sheet | seat which consists of these metal materials.

  Here, as shown in FIG. 3, a hole 5 may be formed in the movable region of the upper electrode 4. FIGS. 3A to 3C are cross-sectional views showing other examples of the embodiment of the variable capacitor according to the present invention, and FIGS. 3D and 3E are plan views in a see-through state, respectively. . Here, in FIGS. 3D and 3E, the support member 3 is shown by hatching in order to make the shape and arrangement of the support member 3 easy to understand.

  One or more holes 5 can be formed in each movable region of the upper electrode 4. For example, the hole 5 can be formed in the center of each movable region as shown in FIG. 3A or as shown in FIG. Alternatively, a plurality of movable regions may be formed depending on the movable region as shown in FIG. 3C.

  Moreover, the shape seen from right above the hole 5 can be an arbitrary shape, for example, a square shape as shown in FIG. 3D, a circular shape as shown in FIG.

  The hole 5 is formed in accordance with the size of each movable region so that the upper electrode 4 in the movable region can be maintained in parallel with the lower electrode 2 in a state where no voltage is applied to the upper electrode 4. The holes 5 do not have to be provided in all the movable regions, and may be selectively formed according to the characteristics and specifications of the variable capacitor.

  By forming such a hole 5 in the movable region of the upper electrode 4, this hole 5 functions as a ventilation hole, and the air resistance when the upper electrode 4 is displaced at a high speed is reduced, so that high speed operation is possible. Variable capacitor.

  In addition, as shown in FIG. 4, a dielectric 6 may be formed between the lower electrode 2 and the upper electrode 4 and formed on the lower electrode 2 in this example. 4A to 4C are cross-sectional views showing still other examples of embodiments of the variable capacitor according to the present invention.

The dielectric 6 includes silicon nitride, silicon oxide, resin, thallium oxide (TaO), zinc oxide (ZnO), barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), strontium barium titanate ((Ba, Sr) TiO ₃ ) or the like is used. As shown in FIG. 4A, the dielectric 6 may be formed only in the portion where the support member 3 is not formed on the lower electrode 2 so as to face each movable region of the upper electrode 4, or as shown in FIG. ) May be formed on the lower electrode 2 including the forming portion of the support member 3 or may be formed on almost the entire surface of the lower electrode 2 as shown in FIG. Here, as shown in FIGS. 4B and 4C, when the dielectric 6 is formed also in the forming portion of the support member 3, the dielectric 6 is formed on the lower electrode 2, What is necessary is just to form the supporting member 3 in this. Further, the dielectric 6 and the support member 3 may be formed by the same material and in the same process.

  The thickness of the dielectric 6 is set according to the distance between the upper electrode 4 and the lower electrode 2 so that the movable region of the upper electrode 4 can be displaced toward the lower electrode 2 in order to obtain a desired capacitance value.

  By disposing such a dielectric 6 between the lower electrode 2 and the upper electrode 4 in the movable region, the dielectric 6 has a higher dielectric constant than that of the atmosphere, so that a variable capacitance capacitor having a larger capacity can be obtained. it can.

  According to each example of the variable capacitor of the present invention manufactured as described above, each movable region of the upper electrode 4 is applied with electrostatic attraction by applying a voltage between the upper electrode 4 and the lower electrode 2. Can be changed to the desired capacitance value stably and accurately.

  Next, an example of a method for manufacturing a variable capacitor according to the present invention will be described with reference to the drawings.

  5 (a) to 5 (e) are cross-sectional views showing respective steps of the example of the method for manufacturing the variable capacitor of the present invention shown in FIG.

  First, as shown in FIG. 5A, a material for forming the lower electrode 2 is formed on the substrate 1, and processed into a desired pattern by a normal photolithography process and etching process to form the lower electrode 2. To do.

  Next, as shown in FIG. 5B, the sacrificial layer 7 made of silicon, for example, by PE-CVD (Plasma Enhanced Chemical Vapor Deposition) is applied on the lower electrode 2 and the upper electrode 4 in a state where no voltage is applied. The sacrificial layer 7 is formed so as to have the same thickness as the distance between the lower electrode 2 and the sacrificial layer 7 where the support member 3 is to be disposed is removed by a normal photolithography process and etching process. Provide.

  Next, as shown in FIG. 5C, the support member 3 is formed on the portion where the sacrificial layer 7 is not formed on the lower electrode 2. For example, a material for forming the support member 3 is formed by PE-CVD so as to fill a portion where the sacrificial layer 7 is not formed, and exceeds the portion formed on the sacrificial layer 7 and the thickness of the sacrificial layer 7. The formed part may be removed using a normal photolithography process and an etching process, and the support member 3 may be formed in a portion where the sacrificial layer 7 is not formed on the lower electrode 2.

  Next, as shown in FIG. 5D, a material for forming the upper electrode 4 is formed by sputtering or the like so as to cover the sacrificial layer 7 and the support member 3, and a normal photolithography process and etching process are performed. The upper electrode 4 is formed by processing into a desired pattern.

  In conventional electrostatic drive type variable capacitors, the thickness of the upper electrode is non-uniform, so the way the force attracted to the lower electrode side of the upper electrode due to electrostatic attraction becomes non-uniform in the plane of the upper electrode, There was a problem that the operation was not stable. However, by forming the upper electrode 4 on the sacrificial layer 7 and the support member 3, the upper electrode 4 having a uniform thickness over a wide area can be obtained. For this reason, the operation of the variable capacitor of the present invention can be stabilized.

Finally, as shown in FIG. 5E, the sacrificial layer 7 is selectively removed by etching to obtain the variable capacitor of the present invention. For example, in order to selectively remove the sacrifice layer 7 made of silicon by etching, dry etching may be performed using XeF ₂ gas.

  Note that the variable capacitor of the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the gist of the present invention.

  Next, a first embodiment of the present invention will be described with reference to a variable capacitor shown in FIGS. 1A and 2A manufactured by each step shown in FIG.

  First, as shown in FIG. 5A, a Cr / Au layer structure (thickness of each layer: 0.01 μm / 0.1) is formed by sputtering Cr and Au as materials for forming the lower electrode 2 on a substrate 1 made of glass. μm). Here, the electrode materials are represented in the order of lower layer / upper layer (the same applies to the following). Next, this layer was processed into a desired pattern by a normal photolithography process to form the lower electrode 2.

  Next, as shown in FIG. 5B, a sacrificial layer 7 made of silicon is formed to a thickness of 3.0 μm by PE-CVD, and the sacrificial layer 7 at a position where the support member 3 is disposed by a normal etching process. The sacrificial layer 7 was not formed.

Next, as shown in FIG. 5C, SiO ₂ is formed to a thickness of 3.0 μm by PE-CVD so as to fill the non-formation portion of the sacrificial layer 7 and formed on the sacrificial layer 7. The formed part and the part formed exceeding the thickness of the sacrificial layer 7 were removed by a normal photolithography process, and the support member 3 made of SiO ₂ was formed on the non-formed part of the sacrificial layer 7 on the lower electrode 2.

  Next, as shown in FIG. 5D, a Cr / Au layer structure (thickness of each layer: thickness) is formed by sputtering Cr and Au as materials for forming the upper electrode 4 so as to cover the sacrificial layer 7 and the support member 3. 0.01 μm / 0.1 μm) and processed into a desired pattern using a normal photolithography process to form the upper electrode 4.

  Next, as shown in FIG. 5E, the sacrificial layer 7 was selectively removed by etching with XeF2 gas to obtain a variable capacitor.

  A plurality of variable capacitors according to the first embodiment were manufactured, and the capacitance values were measured by changing the values of the voltages applied to the upper electrode 4 and the lower electrode 2, and as a result, the capacitance values for the designed capacitance values of the respective variable capacitors were measured. The variation in measurement results was about 0.5%.

  Further, when the capacitance value of the variable capacitor of the first embodiment was measured in a vibration environment that vibrates at the same frequency as the resonance frequency of the variable capacitor of the first embodiment, The capacity change in the vibration environment was about 0.5%.

  Further, the variable capacitance capacitor of the first embodiment was mounted on a mounting board on which the power supply line and the high-frequency signal line were wired, and the capacitance value was measured in an environment with electrical noise from the power supply line and the high-frequency signal line. However, the change in capacitance in an environment with electrical noise compared with the capacitance value without electrical noise was about 0.1%.

  Next, a second embodiment of the present invention will be described with reference to variable capacitors shown in FIGS. 3 (a) and 3 (d). 6 (a) to 6 (f) are cross-sectional views showing respective steps of the variable capacitor manufacturing method shown in FIGS. 3 (a) and 3 (d) of the present invention.

  As in the first embodiment, as shown in FIGS. 6A to 6D, the lower electrode 2, the sacrificial layer 7, and the support member 3 are formed on the substrate 1, and the sacrificial layer 7 and the support member 3 are formed. The upper electrode 4 was formed so as to cover it.

  Next, as shown in FIG. 6E, a part of the upper electrode 4 was removed at the center of each movable region of the upper electrode 4 by ordinary photolithography to form a hole 5.

  Next, as in the first example, the sacrificial layer 7 was removed as shown in FIG. 6F to obtain a variable capacitor.

  A plurality of variable capacitors of the second embodiment were produced, and the capacitance values were measured by changing the values of the voltages applied to the upper electrode 4 and the lower electrode 2. As a result, the capacitance values of the respective variable capacitors were designed. The variation in measurement results was about 0.5%.

  Further, when the capacitance value of the variable capacitor of the second embodiment was measured in a vibration environment that vibrates at the same frequency as the resonance frequency of the variable capacitor of the second embodiment, The capacity change in the vibration environment was about 0.5%.

  Furthermore, the variable capacitance capacitor of the second embodiment was mounted on a mounting substrate on which the power supply line and the high-frequency signal line were wired, and the capacitance value was measured in an environment where there was an electrical noise from the power supply line and the high-frequency signal line. However, the change in capacitance in an environment with electrical noise compared with the capacitance value without electrical noise was about 0.1%.

  Further, the response speed of the variable capacitor of the second embodiment is faster than that of the first embodiment.

  Next, a third embodiment of the present invention will be described with reference to a variable capacitor shown in FIG. 7A to 7F are cross-sectional views showing respective steps of the method for manufacturing the variable capacitor shown in FIG. 4 of the present invention. The shape seen from directly above the support member 3 was the same as that shown in FIG.

  Similar to the first embodiment, a lower electrode 2 was formed on a substrate 1 as shown in FIG.

  Next, as shown in FIG. 7B, a ZnO film having a thickness of 2.0 μm is formed on the lower electrode 2 by a sputtering method, and the formed ZnO film is formed by a normal photolithography process. A dielectric 6 made of ZnO was formed by processing into a desired pattern.

  Next, as in the first embodiment, as shown in FIGS. 6C to 6F, a sacrificial layer 7 and a support member 3 are formed on the dielectric 6 and the lower electrode 2, and the sacrificial layer 7 and After the upper electrode 4 was formed so as to cover the support member 3, the sacrificial layer 7 was removed to obtain a variable capacitor.

  A plurality of variable capacitors of the third embodiment were produced, and the capacitance values were measured by changing the values of the voltages applied to the upper electrode 4 and the lower electrode 2. As a result, the capacitance values designed for each variable capacitor were measured. The variation in measurement results was about 0.5%.

  Further, regarding the variable capacitor of the third example, when the capacitance value was measured in a vibration environment that vibrates at the same frequency as the resonance frequency of the variable capacitor of the third example, The capacity change in the vibration environment was about 0.5%.

  Furthermore, the variable capacitance capacitor of the third embodiment was mounted on a mounting substrate on which the power supply line and the high-frequency signal line were wired, and the capacitance value was measured in an environment with electrical noise from the power supply line and the high-frequency signal line. However, the change in capacitance in an environment with electrical noise compared with the capacitance value without electrical noise was about 0.1%.

  Furthermore, the variable capacitance capacitor of the third embodiment has a larger capacity than that of the first embodiment.

  Next, as a comparative example, the lower electrode 2 is formed on the substrate 1 and the sacrificial layer 7 is formed on the entire surface of the lower electrode 2 by using the same material and manufacturing method as in the first embodiment. The support member 3 is formed on the substrate 1 so as to form an outer frame surrounding the substrate 2, the upper electrode 4 is formed so as to cover the sacrificial layer 7 and the support member 3, and then the sacrificial layer 7 is removed to form the lower electrode 2 and a variable capacitor without the support member 3 were prepared in the opposite part of the upper electrode 4.

  Here, the area where the upper electrode 4 and the lower electrode 2 face each other and the height of the support member 3 were set to coincide with those of the variable capacitors shown in Examples 1 to 3.

  A plurality of variable capacitance capacitors of this comparative example were produced, and the capacitance values were measured by changing the values of the voltages applied to the upper electrode 4 and the lower electrode 2, and as a result of the measurement results for the designed capacitance values of each variable capacitor. The variation was about 5%.

  Moreover, when the capacitance value of the variable capacitor of the comparative example was measured in a vibration environment that vibrates at the same frequency as the resonance frequency of the variable capacitor of the comparative example, the capacitance in the vibration environment compared to the capacitance value when not vibrating. The change was about 20%.

  Furthermore, when the variable capacitor of the comparative example was mounted on the mounting board on which the power line and the high-frequency signal line were wired, and the capacitance value was measured in an environment with electrical noise from the power line and the high-frequency signal line, The capacitance change in an environment with electrical noise was about 5% compared to the capacitance value in the absence of static noise.

  From the above results, the variable capacitance capacitors according to the first to third embodiments of the present invention are variable capacitance capacitors in which variation with respect to the designed capacitance value is suppressed as compared with the variable capacitance capacitors of the comparative example. I understood that.

  Moreover, since the upper electrode 4 is divided into a plurality of movable regions and each movable region is supported by the support member 3, the upper electrode 4 of each movable region is stably displaced to the lower electrode 2 side. By applying a voltage to the upper electrode 4 and the lower electrode 2, it was possible to obtain a desired capacitance value with high accuracy.

  Furthermore, the upper electrode 4 is divided into a plurality of movable regions, and each movable region is supported by the support member 3, so that the upper electrode 4 in the movable region is unnecessarily vibrated due to external vibration, electrical noise, or the like. Since this can be suppressed, it has been found that the variable capacitance capacitor can obtain a stable capacitance value that is not affected by external vibration, electrical noise, or the like.

  Further, according to the variable capacitor of the second embodiment of the present invention, since the hole 5 is opened in the movable region of the upper electrode 4, it can operate at a higher speed than the variable capacitor of the first embodiment. It turns out that it becomes the variable capacitor which can be.

  Furthermore, according to the variable capacitor of the third embodiment of the present invention, since the dielectric 6 is disposed between the lower electrode 2 and the upper electrode 4 in the movable region, the variable capacitor of the first embodiment. It turns out that it becomes a larger capacity variable capacitor than the capacitor.

It is sectional drawing which shows an example of embodiment of the variable capacitor of this invention. (A)-(c) is a top view of the see-through state which shows the example of the shape and arrangement | positioning of the supporting member in the variable capacitor shown in FIG. 1, respectively. (A)-(c) is sectional drawing which shows the other example of embodiment of the variable capacitor of this invention, respectively, (d), (e) is a top view of a see-through state, respectively. (A)-(c) is sectional drawing which shows the further another example of embodiment of the variable capacitor of this invention, respectively. (A)-(e) is sectional drawing which shows each process of the manufacturing method of the variable capacitor of this invention, respectively. (A)-(f) is sectional drawing which shows each process of the manufacturing method of the variable capacitor of this invention, respectively. (A)-(f) is sectional drawing which shows each process of the manufacturing method of the variable capacitor of this invention, respectively. (A), (b) is sectional drawing which shows the example of the conventional variable capacitor, respectively.

Explanation of symbols

1: Substrate 2: Lower electrode 3: Support member 4: Upper electrode 5: Hole 6: Dielectric 7: Sacrificial layer

Claims (3)

A lower electrode having a large area is formed on the substrate, an upper electrode having a large area is disposed to face the lower electrode, and the upper electrode is moved between the lower electrode and the upper electrode. An insulating support member is arranged to divide each region into the lower electrode side, and a variable capacitance capacitor. The variable capacitor according to claim 1, wherein a hole is opened in the movable region of the upper electrode. The variable capacitor according to claim 1, wherein a dielectric is disposed between the lower electrode and the upper electrode in the movable region.

Images