JP2006328955A - Energy conversion element and electrostatic driving element equipped with the same, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy conversion element capable of reducing drive voltage and drive current (power consumption), and an electrostatic driving element equipped with the same. <P>SOLUTION: A conductive cantilever 13 (a first cantilever) is provided to a first substrate 11 side. When drive current I is supplied to the cantilever 13, a beam part 13A is horizontally extended by thermal expansion. After the direction of the beam part 13A is converted in a direction conversion part 14, a cantilever 25 (a second cantilever) on a second substrate 12 side is lifted. When the cantilever 25 comes close to a first electrode 22, a signal input part 25C is brought into contact with an input wiring 23 and an output wiring 24 by electrostatic force therebetween so as to make a signal circuit 'closed'. When a thermal driving power source is turned off, the 'closed' state of the signal circuit is maintained by the electrostatic force while the cantilever 13 is restored. When electrostatic driving power source is turned off, the signal circuit is 'opened' by separating the signal input part 25C from the input wiring 23 and output wiring 24 by restoring force of the cantilever 25 itself. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an energy conversion element for converting electrical energy into a mechanical operation, an electrostatic drive element including the energy conversion element, and an electronic apparatus including the electrostatic drive element.

  In recent years, micro electro mechanical systems (MEMS) elements and small devices incorporating the MEMS elements have attracted attention. A basic feature of the MEMS element is that a driving body configured as a mechanical structure is incorporated in the element.

  In particular, a driver formed using a micromachining technology based on a semiconductor process has characteristics such as a small device occupation area, a high Q value, and integration with other semiconductor devices. Therefore, it has been proposed to use the wireless communication device as an intermediate frequency (IF) or a radio frequency (RF) electrostatic drive element (for example, Non-Patent Document 1).

In addition, as a method for driving such an element, a driving electrode is provided together with the element and an electrostatic force (Coulomb force) is generated between them (Non-Patent Document 1), or driving is performed by heating the driving body. A method (for example, Patent Document 1) is proposed. In particular, a driving method using electrostatic force is used as one of the excellent control methods because it can be easily controlled with a simple configuration in which only the driving electrode is provided and power consumption can be reduced. .
Jay. R. Clark (JRClark), double. -T. Hsu, C. Tee. -CT-C. Nguyen, “High-Cube Etch F Micromechanical Counter-Mode Disc Resonators,“ Technical Digest, IAE I.N. Electron Devices Meeting, San Francisco, California, (“High- QVHF micromechanical contour-mode disk resonators, "Technical Digest, IEEE Int. Electron Devices Meeting, San Francisco, California), Dec. 11-13, 2000, p. 399-402 JP 2004-55410 A

  However, in the conventional driving method using electrostatic force, a high voltage of 20 V or more has to be applied, which is an obstacle to integration with other semiconductor elements, and the driving method using heating is driving. During this time, it is necessary to continue to supply the drive current, which causes problems such as increased power consumption.

  The present invention has been made in view of such problems, and a first object thereof is an electrostatic drive element capable of electrostatic drive even at a low voltage and capable of greatly reducing power consumption, and the same. The object is to provide an electronic device using the.

  A second object of the present invention is to provide an energy conversion element that can convert electrical energy into mechanical energy by the MEMS structure and can be suitably used for the electrostatic drive element as described above. .

  One aspect of the energy conversion element according to the present invention is provided on a substrate, includes a beam portion and a support portion that supports the beam portion, and a conductive cantilever beam that can be extended by thermal expansion. It is provided with the direction conversion part which is provided in the position facing an upper beam part, and changes the extending | stretching direction of the front-end | tip of a beam part, and the 1st drive means which supplies a drive current to a cantilever beam.

  In this energy conversion element, when a drive current is supplied to the cantilever beam by the first drive means, the beam portion is extended by the thermal expansion, and the extension direction is changed after contacting the direction changing portion. That is, electrical energy is converted into mechanical energy via thermal energy, and by using this, it is possible to realize a low voltage driven electrostatic drive element.

  That is, the electrostatic drive element according to the present invention includes the energy conversion element described above, and can be, for example, in the following modes.

  An electrostatic driving element according to the present invention includes, as a first aspect, a conductive first electrode that is provided on a substrate, includes a beam portion and a support portion that supports the beam portion, and the beam portion can be extended by thermal expansion. A cantilever beam, a direction changing portion provided at a position facing the beam portion on the substrate, for changing the extending direction of the tip of the beam portion, a first drive means for supplying a drive current to the cantilever beam, and a beam A drive electrode provided at a position opposite to the tip of the part, and a second drive means for applying a voltage to the cantilever and the drive electrode and displacing the direction-changed beam part to the drive electrode side by the generated electrostatic force It has the structure provided with. Here, after the cantilever is displaced to the drive electrode side by electrostatic force, it is preferable to cut off the supply of the drive current by the first drive means.

  In this electrostatic driving element, a driving current is supplied to the cantilever by the first driving means, and a voltage for electrostatic driving is applied between the cantilever and the driving electrode by the second driving means. . Thereby, the beam portion of the cantilever is thermally expanded and extended, and the extending direction of the beam portion is changed to the second substrate side by the direction changing portion. When the tip approaches the drive electrode, the beam portion is attracted to the drive electrode by electrostatic force between the beam and the drive electrode.

  An electrostatic driving element according to the present invention has, as a second aspect, a first substrate and a second substrate arranged to face each other, and is provided on the first substrate and supports the beam portion and the beam portion. A conductive first cantilever beam that can be extended by thermal expansion and a position on the first substrate that faces the beam portion. A direction changing portion for converting to the two substrate side, a first driving means for supplying a driving current to the cantilever, a first electrode provided on the second substrate, and a first electrode provided on the second substrate A second cantilever having a second electrode opposite to the first electrode, the tip of which can be displaced in the direction of the second substrate by the contact of the first cantilever whose direction has been changed, and the first electrode and the second electrode And a second drive for displacing the second cantilever to the second substrate side by the generated electrostatic force. And it has a configuration including a stage, a. Here, after the second cantilever is displaced toward the second substrate due to electrostatic force, it is preferable to cut off the supply of drive current by the first drive means.

  In this electrostatic drive element, on the first substrate side, a drive current is supplied to the first cantilever by the first drive means, and on the second substrate side, the first electrode and the first electrode are supplied by the second drive means. An electrostatic drive voltage is applied between the second electrode on the two cantilever side. As a result, on the first substrate side, the first cantilever is extended by the thermal expansion of the first cantilever, and after the direction changer changes the direction, the first cantilever changes the second cantilever. Push up in the direction of two electrodes. When the second cantilever approaches the first electrode, the electrostatic force generated by the voltage application to the first electrode and the second electrode is effectively applied, and the second cantilever is moved to the second substrate side. Sucked.

  Therefore, in this electrostatic drive element, if the open / close portion of the signal circuit is configured between the second substrate and the second cantilever, the open / close operation of the signal circuit is accompanied by the displacement of the second cantilever. (Switching) etc. will be performed.

  According to the energy conversion element of the present invention, the drive current is supplied to the conductive cantilever and is extended by thermal expansion, and the extension direction of the cantilever is changed in the direction changing portion. Can easily convert electrical energy into mechanical motion.

  In addition, since the electrostatic driving element of the present invention uses this energy conversion element, it is possible to perform electrostatic driving at a low voltage, and supply of a driving current for thermal driving effectively uses electrostatic force. It can be shut off after it has acted, i.e. it is not necessary to continue to supply current during driving. Therefore, power consumption can be reduced as a whole, and integration into an electronic device is possible. Therefore, in an electronic device equipped with this electrostatic drive element, operations such as signal input / output can be performed with low power consumption.

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

(First embodiment)
FIG. 1 shows a cross-sectional structure of an electrostatic drive element according to the first embodiment of the present invention. The electrostatic driving element 10 includes a first substrate 11 and a second substrate 12. An insulating film 11A is formed on the surface of the first substrate 11, and an insulating film 12A is formed on the surface of the second substrate 12. In addition, since one aspect | mode of the energy conversion element which concerns on this invention is corresponded to the structure by the side of the 1st board | substrate 11 of this electrostatic drive element 10, suppose that it demonstrates collectively below.

  A pair of cantilevers 13 are provided on the first substrate 11 so as to face each other. Between the two cantilever beams 13 and 13 (first cantilever beam), a direction changing portion 14 is provided with a certain distance from them. The direction changing part 14 changes the direction of the tip of the beam part 13A extended by thermal expansion upward (to the second substrate 12 side) as will be described later. The direction changing portion 14 has, for example, a quadrangular pyramid shape, has inclined surfaces 14a on both sides, and a protective film 14A is formed on the surface thereof. Corresponding to the inclined surface 14 a of the direction changing portion 14, an inclined surface 13 a is provided at the tip of each beam portion 13 A of the cantilever beams 13 and 13.

  On the other hand, the second substrate 12 is provided with drive electrodes 15 and 15 at positions facing the tips of the two cantilevers 13, and the drive electrodes 15 and 15 have an insulating film 15 </ b> A formed on the surface thereof. Has been. Note that the surfaces of the drive electrodes 15 and 15 have an inclined surface 15a at a position facing the tip of the beam portion 13A that is warped upward by stretching. The inclined surface 15a is inclined so as to follow the opposing surface of the warped beam portion 13A. Thereby, the suction of the beam portion 13A by the second drive means (electrostatic drive) described later is suitably performed.

  Spacers (not shown) are interposed between the first substrate 11 and the second substrate 12, and the two substrates are held at regular intervals.

The first substrate 11 is made of a semiconductor material such as silicon (Si). The insulating film 11A electrically separates the cantilever 13 from the first substrate 11, and is composed of, for example, a single layer or a plurality of layers made of silicon nitride (SiN) or silicon dioxide (SiO ₂ ). Specifically, it is composed of a silicon thermal oxide film having a thickness of 20 nm and a silicon nitride thin film having a thickness of 20 nm laminated in this order. The second substrate 12 has the same configuration as the first substrate 11.

  The cantilever beam 13 is a thermally driven beam having a structure in which one end portion of the beam portion 13A is supported by a support portion (anchor) 13B. The cantilever 13 is made of, for example, polycrystalline silicon, and has conductivity when an impurity such as phosphorus (P) is added. Further, the planar structure of the cantilever 13 has a U-shape as shown in FIG. That is, the support portion 13B is divided into two branch portions, and both ends thereof are the first terminal 13B1 and the second terminal 13B2. The first terminal 13B1 is connected to one electrode of a DC power supply (not shown), and the second terminal 13B2 is connected to the other electrode. That is, in this cantilever beam 13, the drive current I is supplied from the first terminal 13B1 to the second terminal 13B2 through the beam portion 13A. As a result, the beam portion 13A is thermally expanded and the direction changing portion 14 is thus expanded. The tip of the beam portion 13A is turned upward along the inclined surface 14a of the direction changing portion 14 during the drawing. When the supply of the drive current I is stopped and cooled, the beam portion 13A is restored to the shape before stretching. The first driving means of the present invention is constituted by the power source for supplying the driving current I to the cantilever 13 as described above. This power source is not limited to a DC power source, and an AC power source may be used.

  In order for the beam portion 13A to be changed in direction by the direction changing portion 14, the extended length of the beam portion 13A (extension length L1) is the tip of the beam portion 13A on the first substrate 11 side (lower tip portion). With reference to 13A3, the horizontal distance is equal to or greater than the value obtained by adding the height of the direction changer 14 to the horizontal distance L2 from the lower tip 13A3 to the direction changer 14 or the length of the inclined surface 14a of the direction changer 14. It is preferable that it is more than the value which added L2.

Based on this, the length L3 in the extending direction of the portion to be heated is a length determined by L3 = L1 / T / α (α: thermal expansion coefficient of silicon, T: heating range of the heated portion). It is preferable. Specifically, for example, when the height of the direction changing portion 14 is 1 μm and the inclination angle of the inclined surface is 45 °, the extension length L1 is “1 μm + horizontal distance L2” or more or “1.4 μm + horizontal distance L2” or more. Yes, the length L3 of the heated portion is 0.23 mm when the stretch length L1 is approximated to 1.4 μm, the thermal expansion coefficient α of silicon is 11 × 10 ⁻⁶ / K, and the temperature rise width T is 600 degrees. It is.

  In addition, it is preferable to provide a gap 13C as shown in FIG. 3 in the beam portion 13A of the cantilever 13 in the vicinity of the support portion 13B. By this gap 13C, the driving current I can be divided into two in the thickness direction to adjust the balance of heat generation efficiency, and the beam portion 13A can be efficiently warped upward with a smaller driving current I. Further, for example, with the lower surface of the gap 13C as a boundary, the region of the beam portion 13A is divided vertically, and the impurity doping amount (that is, conductivity) of the lower beam portion 13A1 is made larger than that of the upper beam portion 13A2, You may make it control the beam part 13A more efficiently by making elongation rate of the side beam part 13A1 relatively larger than that of the upper beam part 13A2.

  The direction changing unit 14 is made of, for example, silicon dioxide. The protective film 14A is for protecting the surface of the direction changing portion 14 and for smoothly changing the direction of the extended beam portion 13A. For example, an insulating material such as silicon nitride is deposited to a thickness of 100 nm. Is.

  The drive electrode 15 is made of, for example, a noble metal such as an aluminum alloy, a tungsten alloy, a copper alloy, or gold. The insulating film 15A is a single layer or a plurality of layers made of, for example, silicon nitride or silicon dioxide, and electrically separates the beam portion 13A and the drive electrode 15 from each other. In addition, when the surface of the beam portion 13A is thermally oxidized to form an insulating film, the insulating film 15A need not be provided separately. A voltage for electrostatic drive is applied between the drive electrode 15 and the beam portion 13A of the cantilever 13 by a DC power source (second drive means) (not shown).

  Next, a method for manufacturing the electrostatic driving element 10 will be described.

  4 to 9 show a method of manufacturing the electrostatic driving element 10 in the order of steps. Except for FIG. 7, FIGS. 4 to 9 show the left part including the direction changing unit 14 shown in FIG. 1 in an enlarged manner.

  First, as shown in FIG. 4A, the surface of the silicon first substrate 11 is oxidized by, for example, a thermal oxidation method to form a silicon thermal oxide film 11A1, and then the silicon thermal oxide film 11A1 is continuously formed. In addition, the insulating film 11A is formed by forming the silicon nitride film 11A2 by, for example, a low pressure CVD (Chemical Vapor Deposition) method. The thicknesses of the silicon thermal oxide film 11A1 and the silicon nitride film 11A2 are each 20 nm, for example.

  Subsequently, as shown in FIG. 4B, by depositing silicon dioxide or the like on the silicon nitride film 11A2 by using a low pressure CVD method or the like, for example, the insulating layer 16 having a thickness of 1 μm is formed. Next, as shown in FIG. 4C, by selectively removing the insulating layer 16 using a reactive ion etching (RIE) method or the like, for example, a square frustum-shaped direction changing portion is formed. 14 is formed.

  Subsequently, as shown in FIG. 5A, for example, a protective film 14A having a thickness of 100 nm is formed by depositing silicon nitride or the like on the surface of the direction changing portion 14 by using a low pressure CVD method or the like.

  Subsequently, as shown in FIG. 5B, an insulating material such as silicon dioxide is formed on the silicon nitride film 11A2 and the protective film 14A by using, for example, a low pressure CVD method until the thickness becomes 100 nm. After the deposition, the sacrificial layers 17A and 17B are formed by patterning using a photolithography process and an etching process.

  Subsequently, as shown in FIG. 5C, by depositing polycrystalline silicon containing phosphorus or the like on the silicon nitride film 11A2 and the sacrificial layers 17A and 17B by using, for example, a low pressure CVD method, A polycrystalline silicon layer 18 is formed.

  Subsequently, as shown in FIG. 6A, the upper surface of the polycrystalline silicon layer 18 is planarized using CMP (Chemical and Mechanical Polishing) to form the upper surface of the beam portion 13A. In addition, the upper surface of the sacrificial layer 17A and a part of the upper surface of 17B are exposed.

  Subsequently, as shown in FIG. 6B, the sacrificial layers 17A and 17B are removed using, for example, a hydrofluoric acid-based etching solution. Thereby, the 1st board | substrate 11 provided with the cantilever 13 is completed.

  Next, the second substrate 12 is manufactured in the same manner as the first substrate 11 illustrated in FIG.

  Subsequently, as shown in FIG. 7, a noble metal such as an aluminum alloy, a tungsten alloy, a copper alloy, or gold is deposited at a predetermined position on the insulating film 12A by using, for example, a sputtering method or a low pressure CVD method. The drive electrode 15 is formed by patterning. Subsequently, silicon nitride or the like is deposited on the surfaces of the drive electrodes 15 to form an insulating film 15A.

  Finally, the electrostatic driving element 10 shown in FIG. 1 is completed by bonding the first substrate 11 and the second substrate 12 with a spacer in between.

  Moreover, the cantilever 13 provided with the space | gap 13C of FIG. 3 can be formed as follows, for example.

  Subsequent to the step shown in FIG. 5B, as shown in FIG. 8A, phosphorus having a thickness of 700 nm, for example, is formed on the surfaces of the silicon nitride film 11A2, the protective film 14A, and the sacrificial layers 17A and 17B. A polycrystalline silicon layer 18A is formed.

  Subsequently, as shown in FIG. 8B, on the polycrystalline silicon layer 18A in the vicinity of the support portion 13B, for example, the same material and the same method as those used when forming the sacrificial layers 17A and 17B are used. Thus, a sacrificial layer 17C having a thickness of 100 nm is formed.

  Subsequently, as shown in FIG. 9, a polycrystalline silicon layer 18B containing phosphorus having a thickness of 500 nm is formed so as to cover the surfaces of the polycrystalline silicon layer 18A and the sacrificial layer 17C. The subsequent steps are the same as the steps shown in FIG. Thereby, the cantilever 13 (FIG. 3) provided with the space 13C is completed.

  Next, the operation of the electrostatic driving element 10 will be described.

  In the electrostatic drive element 10, a drive current I is supplied to the cantilever 13 via the support portion 13 </ b> B, and an electrostatic drive voltage is applied between the cantilever 13 and the drive electrode 15. . As a result, the beam portion 13A of the cantilever beam 13 is thermally expanded and extends horizontally. The extended beam portion 13A abuts on the direction changing portion 14 and further moves along the inclined surface 14a, and the extending direction is changed upward. When the tip of the beam portion 13A approaches the drive electrode 15, the beam portion 13A is attracted to the drive electrode 15 side by the electrostatic force generated between the drive electrode 15 and the beam portion 13A.

  As described above, in the present embodiment, the cantilever 13 is mechanically approached to the drive electrode 15 using thermal expansion before being driven by electrostatic force, so that low-voltage electrostatic drive is performed. In addition, the supply of the drive current for the thermal drive can be cut off after the electrostatic force is effectively applied, that is, it is not necessary to continue supplying the current during the drive. Therefore, power consumption can be reduced as a whole, and integration into an electronic device is possible.

  Also, by providing the cantilever 13 with the gap 13C, the drive current I can be divided into two in the thickness direction to adjust the balance of heat generation efficiency, and the beam 13A can be efficiently moved upward with a smaller drive current I. Can be warped. Further, for example, by dividing the beam portion 13A vertically with the lower surface of the gap 13C as a boundary, the lower beam portion 13A1 has an impurity doping amount (that is, conductivity) larger than that of the upper beam portion 13A2, thereby reducing the lower side. It becomes possible to control the beam portion 13A more efficiently by increasing the elongation ratio of the beam portion 13A1.

(Second Embodiment)
Specifically, the electrostatic drive element can be used as a switch for opening and closing a signal circuit such as a direct current or a high frequency. Hereinafter, the electrostatic driving element 20 will be described with reference to FIG. FIG. 11 shows a planar structure when the second substrate 12 is viewed from the side facing the first substrate 11. Note that the same components as those in the above embodiment are given the same reference numerals and will be described below.

  In the electrostatic driving element 20, the first substrate 11 and the second substrate 12 are disposed to face each other, and a ground film 11C is provided on the back surface of the first substrate 11, and a ground film 12C is provided on the back surface of the second substrate 12. Is provided. The first substrate 11 is the same as the above embodiment except that only one cantilever 13 (first cantilever) is provided on the insulating film 11A. On the other hand, the first wiring 21, the first electrode 22, the input wiring 23, and the output wiring 24 are provided on the insulating film 12A of the second substrate 12, and the first wiring 21 has a cantilever 25 (first 2 cantilevers) are integrated. The first electrode 22 is for generating an electrostatic force between the cantilever 25 and the first electrode 22 is grounded through the second wiring 26 (FIG. 11).

  The ground film 12C is for grounding when a planar type high-frequency line is used, and is made of, for example, an aluminum alloy. Such a ground film 12 </ b> C may be provided on both surfaces of the substrate 12. When a co-planar type high-frequency line is used, the ground film 12C is not necessary, but a ground film is preferably provided in the vicinity of the input wiring 23 and the output wiring 24 that are high-frequency lines.

  The input wiring 23 and the output wiring 24 constitute a signal circuit for transmitting a high frequency signal. The first wiring 21, the first electrode 22, the input wiring 23, the output wiring 24, and the second wiring 26 are made of, for example, a noble metal such as an aluminum alloy, a tungsten alloy, a copper alloy, or gold.

  The cantilever beam 25 includes an insulating beam body 25A, and a second electrode 25B and a signal input unit 25C are provided on the surface of the beam body 25A facing the second substrate 12. The second electrode 25 </ b> B is formed integrally with the first wiring 21. The signal input unit 25C is electrically separated from the second electrode 25B and has two contact points 25C1 and 25C2. A metal film 25D is formed at a position facing the other second electrode 25B of the beam body 25A, and a metal film 25E is formed at a position facing the signal input part 25C.

  Further, a protective film 25F is provided on the surface of the cantilever 25 facing the second substrate 12, and a protective film 25G is provided on the other surface. Further, the cantilever 25 is provided with a fulcrum 25H between the second electrode 25B and the signal input unit 25C, and a fulcrum 25I above the first wiring 21, thereby facilitating deformation. It is designed to be driven smoothly.

  The beam main body 25A forms a skeleton of the cantilever beam 25 and is made of an insulating material such as silicon dioxide. The second electrode 25B is for driving the cantilever 25 together with the first electrode 22 by electrostatic force, and is formed of, for example, a noble metal such as an aluminum alloy, a tungsten alloy, a copper alloy, or gold. Note that the second driving means of the present invention is configured by a DC power source for applying an electrostatic driving voltage between the second electrode 25B and the first electrode 22.

  The signal input section 25C includes contacts 25C1 and 25C2 and is connected to the input wiring 23 and the output wiring 24 simultaneously by connecting them, that is, the signal circuit is closed, and the signal input section 25C is connected to the input wiring 23 and the output wiring 24. The signal circuit is made “open” by leaving, and is made of the same material as the second electrode 25B.

  The contacts 25C1 and 25C2 have a pull-in phenomenon caused by an electrostatic force generated between the first electrode 22 and the second electrode 25B, that is, the distance between the first electrode 22 and the second electrode 25B is not increased by the electrostatic force before the driving voltage is applied. This is for contact with the input wiring 23 and the output wiring 24 before the phenomenon of suddenly attracting each other occurs when the distance is reduced to about two-thirds of the interval. As a result, an extra load received by the cantilever beam 25 can be reduced, and durability against repeated operations can be improved. Specifically, for example, the distance between the second electrode 25B and the first electrode 22 is 1.2 μm, and the distance between each of the contacts 25C1 and 25C2 and the input wiring 23 and the output wiring 24 is 0.5 μm. Thus, the pull-in phenomenon can be suppressed.

  Further, when the contacts 25C1, 25C2, the input wiring 23 and the output wiring 24 are made of the above-described aluminum alloy or the like, an ohmic type (DC contact type) static capable of inputting / outputting a high frequency signal and direct current (DC). It functions as an electric drive element, but by interposing an insulator between the contacts 25C1 and 25C2 and the input wiring 23 and output wiring 24, it is a capacitive (capacitive) static that can input and output only high-frequency signals. It may be an electrically driven element.

  The metal films 25D and 25E are used to reinforce the beam body 25A, and are formed of the same material as that of the second electrode 25B, for example. The protective film 25F is for electrically separating the first electrode 22 and the second electrode 25B and reducing friction during contact. The protective film 25G is for reducing high heat and friction received from the thermally expanded cantilever 13. These protective films 25F and 25G have a thickness of 20 nm, for example, and are formed of an insulating material such as silicon nitride.

  Next, an example of a method for manufacturing the electrostatic driving element 20 will be described.

  Since the manufacturing method of the first substrate 11 is the same as that described in the above embodiment, the description thereof is omitted, and the manufacturing method after the manufacturing process of the second substrate 12 will be described below.

  Following the step shown in FIG. 4 (A), as shown in FIG. 12 (A), an aluminum alloy, tungsten alloy, copper alloy is formed at a predetermined position on the insulating film 12A by using, for example, a low pressure CVD method. Alternatively, the first wiring 21, the first electrode 22, the input wiring 23, the output wiring 24, and the second wiring 26 (the output wiring 24 and the second wiring 26 are not shown) by depositing and patterning a noble metal such as gold. ).

  Subsequently, as shown in FIG. 12B, on the surfaces of the insulating film 12A, the first wiring 21, the first electrode 22, the input wiring 23, the output wiring 24, and the second wiring 26, for example, sputtering, Using a CVD method, a titanium (Ti) -tungsten (W) thin film (not shown) is formed, and then a sacrificial layer 27 is formed by depositing polycrystalline Si (PDAS; phosphorous doped amorphous silicon). The upper surface of 27 is planarized using the CMP method. The Ti-W thin film is for protecting the first wiring 21, the first electrode 22, the input wiring 23, the output wiring 24, and the second wiring 26 in the step of removing the sacrificial layer 27 described later. The sacrificial layer 27 is removed after the removal.

  Subsequently, as shown in FIG. 12C, a protective film 25F is formed on the sacrificial layer 27 by depositing silicon nitride using, for example, a low pressure CVD method and then patterning. Further, by patterning, a contact hole 28 for connecting the first wiring 21 and the second electrode 25B and a signal input portion formation scheduled portion 29 are formed.

  Subsequently, as shown in FIG. 13A, a noble metal such as an aluminum alloy or gold is deposited on the surfaces of the first wiring 21, the protective film 25F, and the sacrificial layer 27 by using, for example, a low pressure CVD method. By patterning, the second electrode 25B, the signal input unit 25C, and the fulcrums 25H and 25I are formed. Also in this case, it is preferable to form a Ti—W thin film (not shown) before depositing an aluminum alloy or the like.

  Subsequently, as shown in FIG. 13B, the cantilever 25 is formed by repeating the step of laminating the constituent materials of the constituent parts and the patterning.

Subsequently, as shown in FIG. 13C, the second substrate 12 including the cantilever beam 25 is completed by removing the sacrificial layer 27 using, for example, XeF ₂ or the like.

  Finally, after bonding the first substrate 11 and the second substrate 12 with a spacer (not shown) in between, an aluminum alloy or the like is formed on the back surfaces of the substrate 11 and the substrate 12 by vapor deposition or the like. By depositing, for example, the ground films 11C and 12C having a thickness of 0.8 μm are formed. Thereby, the electrostatic drive element 20 shown in FIG. 10 is completed.

  Next, the operation of the electrostatic driving element 20 will be described.

  First, when the signal circuit is “closed”, the thermal drive power supply (first drive means) and the electrostatic drive power supply (second drive means) are turned on. Then, when the drive current I is supplied, the cantilever 13 is thermally expanded, and as shown by a two-dot chain line in FIG. 10, the beam 13 </ b> A extends in the horizontal direction and is changed in direction by the direction changer 14. After that, it rises and comes into contact with the cantilever 25. When the cantilever beam 25 approaches the first electrode 22 side, the electrostatic force due to the DC voltage applied between the cantilever beam 25 and the first electrode 22 effectively acts, and the cantilever beam 25 becomes the second substrate. Suction to 12 side. As a result, the contacts 25C1 and 25C2 connect the input wiring 23 and the output wiring 24 with a constant pressure, and the signal circuit is “closed”. Thereafter, the thermal drive power supply is turned off, and the extended cantilever 13 returns to the original state, but the cantilever 25 is still absorbed by the electrostatic force, and the signal circuit remains in the “closed” state.

  Next, when the signal circuit is set to “open”, the electrostatic drive power supply is turned off. As a result, the contacts 25C1 and 25C2 are separated from the input wiring 23 and the output wiring 24 by the restoring force of the cantilever 25 itself, and the signal circuit is “open”.

  As described above, in the electrostatic drive element 20 of the present embodiment, the mechanical force due to the thermal expansion of the cantilever 13 and the electrostatic force acting on the cantilever 25 are used together to perform the “close” operation of the signal circuit. Since the signal circuit is "opened" by the restoring force of the cantilever 25 itself, the amount of driving current, that is, the power consumption and the driving voltage can be kept low. It becomes possible to integrate.

  Next, among electronic devices including such an electrostatic drive element, a communication device will be described in particular. Specific examples of the communication device include a mobile phone, a wireless LAN device, a wireless transceiver, a TV tuner, a radio tuner, and the like.

  FIG. 14 shows a block configuration of the communication apparatus. The electrostatic drive element is mounted as, for example, a transmission / reception switch 101 that switches transmission / reception paths. Further, this communication apparatus includes, for example, a transmission system circuit 100A, a reception system circuit 100B, a high frequency filter 102, and a transmission / reception antenna 103.

  The transmission system circuit 100A includes two digital / analog converters (DACs) 111I and 111Q and two band pass filters 112I and 112Q corresponding to transmission data of I channel and transmission data of Q channel, and modulation. 120, a transmission PLL (Phase-Locked Loop) circuit 113, and a power amplifier 114. The modulator 120 includes two buffer amplifiers 121I and 121Q and two mixers 122I and 122Q corresponding to the two bandpass filters 112I and 112Q, a phase shifter 123, an adder 124, and a buffer amplifier 125. It is comprised including.

  The reception system circuit 100B includes a high-frequency unit 130, a band-pass filter 141 and a channel selection PLL circuit 142, an intermediate frequency circuit 150 and a band-pass filter 143, a demodulator 160 and an intermediate-frequency PLL circuit 144, and I channel reception. Two band-pass filters 145I and 145Q and two analog / digital converters (ADC) 146I and 146Q corresponding to the data and the received data of the Q channel are provided. The high frequency unit 130 includes a low noise amplifier 131, buffer amplifiers 132 and 134, and a mixer 133. The intermediate frequency circuit 150 includes buffer amplifiers 151 and 153, and automatic gain adjustment (AGC; Auto Gain). Controller) circuit 152. The demodulator 160 includes a buffer amplifier 161, two mixers 162I and 162Q corresponding to the two band-pass filters 145I and 145Q, two buffer amplifiers 163I and 163Q, and a phase shifter 164. Yes.

  In this communication apparatus, when I-channel transmission data and Q-channel transmission data are input to the transmission system circuit 100A, each transmission data is processed in the following procedure. That is, first, analog signals are converted by the DACs 111I and 111Q, and signal components other than the band of the transmission signal are subsequently removed by the bandpass filters 112I and 112Q, and then supplied to the modulator 120. Subsequently, the modulator 120 supplies the signals to the mixers 122I and 122Q via the buffer amplifiers 121I and 121Q, continuously mixes and modulates the frequency signal corresponding to the transmission frequency supplied from the transmission PLL circuit 113, and then both By adding the mixed signal in the adder 124, one transmission signal is obtained. At this time, with respect to the frequency signal supplied to the mixer 122I, the phase shifter 123 shifts the signal phase by 90 ° so that the I channel signal and the Q channel signal are orthogonally modulated. Finally, the power is supplied to the power amplifier 114 via the buffer amplifier 125, thereby amplifying the signal to have a predetermined transmission power. The signal amplified by the power amplifier 114 is supplied to the antenna 103 via the transmission / reception switch 101 and the high frequency filter 102 and wirelessly transmitted. The high-frequency filter 102 functions as a band-pass filter that removes signal components other than the frequency band of signals transmitted or received in the communication device.

  The transmission / reception switch 101 is configured by the electrostatic drive element of the above-described embodiment, and enables switching between transmission and reception while reducing signal loss due to its mechanical structure.

  On the other hand, when a signal is received from the antenna 103 via the high frequency filter 102 and the transmission / reception switch 101 to the reception system 100B, the signal is processed in the following procedure. That is, first, in the high frequency unit 130, the received signal is amplified by the low noise amplifier 131, and subsequently, signal components other than the received frequency band are removed by the band pass filter 141, and then supplied to the mixer 133 via the buffer amplifier 132. Subsequently, the frequency signals supplied from the channel selection PPL circuit 142 are mixed, and a signal of a predetermined transmission channel is used as an intermediate frequency signal, which is then supplied to the intermediate frequency circuit 150 via the buffer amplifier 134. Subsequently, in the intermediate frequency circuit 150, signal components other than the band of the intermediate frequency signal are removed by being supplied to the band pass filter 143 through the buffer amplifier 151, and subsequently, the AGC circuit 152 generates a substantially constant gain signal. , And supplied to the demodulator 160 via the buffer amplifier 153. Subsequently, in the demodulator 160, the frequency signal supplied from the intermediate frequency PPL circuit 144 is mixed after being supplied to the mixers 162I and 162Q via the buffer amplifier 161, and the I channel signal component and the Q channel signal component are mixed. And demodulate. At this time, with respect to the frequency signal supplied to the mixer 162I, the phase shifter 164 shifts the signal phase by 90 ° to demodulate the I-channel signal component and the Q-channel signal component that are orthogonally modulated with each other. Finally, the I-channel signal and the Q-channel signal are respectively supplied to the band-pass filters 145I and 145Q to remove signal components other than the I-channel signal and the Q-channel signal, and then supplied to the ADCs 146I and 146Q. Digital data. Thereby, I-channel received data and Q-channel received data are obtained.

  As described above, according to the communication device, since the electrostatic drive element according to the above-described embodiment is mounted, the amount of drive current, that is, power consumption and drive voltage can be suppressed to a low level by the above-described action. Signals can be input and output without using a driving voltage.

  In the communication apparatus shown in FIG. 14, the case where the electrostatic drive element described in the above embodiment is applied to the transmission / reception switch 101 has been described. However, the present invention is not necessarily limited to this, and other signal switchers are used. You may apply to. Even in this case, the same effect can be obtained.

  The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and specific configurations of the energy conversion element, the electrostatic drive element, and the electronic device, and methods for manufacturing the same The procedure and the like can be freely modified as long as the same effects as those in the above embodiment can be obtained.

  For example, in the above-described embodiment, the energy conversion element or the electrostatic drive element is configured such that the first substrate and the second substrate are arranged to face each other. An energy conversion element and an electrostatic drive element that are driven in a direction parallel to the substrate may be used.

  Further, in the above embodiment, the case where the electrostatic driving element of the present invention is applied to an electronic device typified by a communication device such as a mobile phone has been described. It is also possible to apply to other electronic devices. In any of these cases, the same effect as that of the above embodiment can be obtained.

It is sectional drawing showing the structure of the electrostatic drive element which concerns on the 1st Embodiment of this invention. It is a top view showing a part of electrostatic drive element shown in FIG. It is sectional drawing showing the modification of the electrostatic drive element shown in FIG. It is sectional drawing for demonstrating the manufacturing process of the electrostatic drive element which concerns on the 1st Embodiment of this invention. FIG. 5 is a cross-sectional view for explaining a step following the step in FIG. 4. FIG. 6 is a cross-sectional view for explaining a step following the step in FIG. 5. FIG. 7 is a cross-sectional view for explaining a step following the step in FIG. 6. It is sectional drawing for demonstrating the other process following FIG. 5 (B). FIG. 9 is a cross-sectional view for explaining a step following the step in FIG. 8. It is sectional drawing showing the structure of the electrostatic drive element which concerns on the 2nd Embodiment of this invention. It is a top view showing a part of electrostatic drive element shown in FIG. It is sectional drawing for demonstrating the manufacturing process of the electrostatic drive element which concerns on the 2nd Embodiment of this invention. It is sectional drawing for demonstrating the process following FIG. It is a block diagram showing the block configuration of the electronic device (communication device) carrying the electrostatic drive element which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 ... Electrostatic drive element, 11 ... 1st board | substrate, 11A ... Insulating film, 11A1 ... Silicon thermal oxide film, 11A2 ... Silicon nitride film, 11C, 12C ... Grounding film, 12 ... 2nd board | substrate, 12A, 15A ... Insulating film, 13 ... cantilever (first cantilever), 13a, 14a, 15a ... inclined surface, 13A ... beam portion, 13A1 ... lower beam portion, 13A2 ... upper beam portion, 13A3 ... tip, 13B ... Supporting part, 13B1 ... first terminal, 13B2 ... second terminal, 13C ... gap, 14 ... direction changing part, 14A, 25F, 25G ... protective film, 15 ... driving electrode, 16 ... insulating layer, 17A-17C, 27 ... Sacrificial layer, 18, 18A, 18B ... polycrystalline silicon layer, 21 ... first wiring, 22 ... first electrode, 23 ... input wiring, 24 ... output wiring, 25 ... cantilever (second cantilever), 25A ... beam main body, 25B ... second electrode, 25 C: Signal input unit, 25C1, 25C2 ... Contact, 25D, 25E ... Metal film, 25H, 25I ... Support point, 26 ... Second wiring, 28 ... Contact hole, 29 ... Signal input unit formation planned part, 101 ... Transmission / reception switch , 102 ... high frequency filter, 103 ... antenna

Claims (12)

A conductive cantilever that is provided on the substrate and includes a beam portion and a support portion that supports the beam portion, the beam portion being extendable by thermal expansion;
A direction changing portion that is provided at a position facing the beam portion on the substrate and changes the extending direction of the tip of the beam portion;
An energy conversion element comprising: first driving means for supplying a driving current to the cantilever. A conductive first cantilever beam provided on the substrate and including a beam portion and a support portion supporting the beam portion, the beam portion being extendable by thermal expansion;
A direction changing portion that is provided at a position facing the beam portion on the substrate and changes the extending direction of the tip of the beam portion;
First driving means for supplying a driving current to the cantilever;
A drive electrode provided at a position facing the tip of the beam portion;
An electrostatic drive element comprising: second drive means for applying a voltage to the cantilever and the drive electrode and displacing the direction-changed beam portion toward the drive electrode by an electrostatic force generated. . The substrates are a first substrate and a second substrate disposed to face each other,
Including at least the cantilever and the direction changer on the first substrate;
The electrostatic drive element according to claim 2, wherein at least the drive electrode is provided on the second substrate. The electrostatic drive element according to claim 2, wherein after the electrostatic force acts on the cantilever and is displaced toward the drive electrode, the supply of the drive current by the first drive unit is interrupted. The electrostatic drive element according to claim 2, wherein the support portion of the cantilever is branched into two, and a drive current flows from one branch portion to the other branch portion through the beam portion. The electrostatic drive element according to claim 2, wherein a gap portion is provided at a position in the vicinity of the support portion of the beam portion, and the drive current is divided into two in the thickness direction in the gap portion. The electrostatic drive element according to claim 6, wherein the electric conductivity differs in the upper and lower directions in the thickness direction of the beam portion divided into two by the gap portion. The electrostatic drive element according to claim 2, wherein the cantilever beam and the direction changing portion have inclined surfaces on opposite surfaces. An electrostatic drive element having a first substrate and a second substrate disposed opposite to each other,
A conductive first cantilever beam provided on the first substrate and including a beam portion and a support portion supporting the beam portion, the beam portion being extendable by thermal expansion;
A direction changing portion that is provided at a position facing the beam portion on the first substrate, and converts the extending direction of the tip of the beam portion to the second substrate side;
First driving means for supplying a driving current to the cantilever;
A first electrode provided on the second substrate;
The second electrode is provided on the second substrate and faces the first electrode, and the tip thereof is displaced in the second substrate direction by the contact of the first cantilever beam whose direction has been changed. A possible second cantilever beam;
And a second driving means for applying a voltage between the first electrode and the second electrode and displacing the second cantilever beam toward the second substrate by the generated electrostatic force. An electrostatic drive element. An opening / closing part of a signal circuit is configured between the second substrate and the second cantilever, and the signal circuit is opened / closed by electrostatic driving of the second cantilever. Item 10. The electrostatic drive element according to Item 9. The electrostatic drive element according to claim 9, wherein after the electrostatic force acts on the cantilever and is displaced toward the drive electrode, the supply of drive power by the first drive unit is interrupted. An electronic device equipped with an electrostatic drive element,
The electrostatic driving element includes a first substrate and a second substrate disposed to face each other, and
A conductive first cantilever beam provided on the first substrate and including a beam portion and a support portion supporting the beam portion, the beam portion being extendable by thermal expansion;
A direction changing portion that is provided at a position facing the beam portion on the first substrate, and converts the extending direction of the tip of the beam portion to the second substrate side;
First driving means for supplying a driving current to the cantilever;
A first electrode provided on the second substrate;
The second electrode is provided on the second substrate and faces the first electrode, and the tip thereof can be displaced in the second substrate direction by the contact of the first cantilever beam whose direction has been changed. A second cantilever,
And a second driving means for applying a voltage between the first electrode and the second electrode and displacing the second cantilever beam toward the second substrate by the generated electrostatic force. Electronic equipment.

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