JP2006351385A - Electrostatic driving element, and electronic apparatus provided with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic driving element capable of reducing signal loss, improving reliability with a passage of time, and reducing power consumption. <P>SOLUTION: A both-end-fixed beam 20 is provided on a substrate 11. It is obtained by integrating the beam main body 21 with a wing piece part 23, and first contacts 25A, 25B are provided at both ends (free edge) of wing piece part 23 respectively. A first electrode 13 is arranged on the substrate 11 side and a second electrode 24 (divided electrodes 24A to 24C) is arranged in opposition at the wing piece part 23. The first electrode 13 has a protruding part 13A (fulcrum part) and its surface is covered by insulating membrane 15. A signal circuit including the second contacts 14, 14 is formed on the substrate 11 side in opposition to the first contacts 25A, 25B. The wing piece part 23 is deformed at the protruding part 13A (fulcrum part) by the action of electrostatic force, while the first contacts 25A, 25B slide sideways against the second contact point 14 with a fixed pressure and made to contact with it. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrostatic drive element that performs a closing operation of a signal circuit by electrostatic drive, and an electronic apparatus including the same.

  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 a switching element for an intermediate frequency (IF) signal or a radio frequency (RF) signal (for example, Non-Patent Document 1).

In this switching element, a signal circuit is composed of a signal wiring formed on a semiconductor substrate and a contact (first contact) provided on a beam (driving body), and a first contact on the beam side and a signal wiring side. The signal is switched, branched, or mixed by setting the contact state (second contact) to the “closed” state and the non-contact state to the “open” state. Some of such elements use electrostatic force as means for driving the beam (Non-Patent Document 1).
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

  In the conventional switching element as described above, the degree of freedom of the contact portion on the beam side is small, and the contact can be moved in a plane parallel to the substrate or in a direction perpendicular to the substrate. However, in such a structure, the bounce phenomenon at the contact point is a problem, and this phenomenon substantially defines the operation characteristics of connection / disconnection of the contact point. That is, when this phenomenon occurs, it takes time to stabilize the contact state, the operation speed is slowed, and the number of operations is substantially increased, and the life of the contact is shortened. In particular, when the contact is of the direct connection type (DC contact), there is a possibility that discharge occurs between the contacts in the energized state, and the life of the contact is further shortened. Therefore, in order to reduce the signal loss at the contact point and ensure the stability over time, it is extremely important to prevent the occurrence of such a bounce phenomenon.

  Further, in order to connect the contacts stably, further pressing operation is necessary after the contacts come into contact with each other, and the beam structure supporting the contacts is required to have high rigidity. Examples of a method for imparting high rigidity to the beam include a method in which the movable part of the beam is thickened or a heavy material is used. However, in a beam structure having high rigidity by such a method, a large force is required for its deformation, and much energy is consumed for operation. Reduction of energy consumption is the most basic and general requirement for electronic components. From the viewpoint of reducing energy consumption, effective rigidity is mechanically applied before and after contact of contacts. Realization of a changing structure is desired.

  The present invention has been made in view of such problems, and a first object thereof is an electrostatic drive capable of reducing the signal loss by suppressing the occurrence of the bounce phenomenon at the contact point and reducing the signal loss and ensuring the stability over time. An object is to provide an element and an electronic device using the element.

  In addition, the second object of the present invention has a structure in which the effective rigidity of the beam changes before and after the contact of the contact point, and reduces energy consumption without forming the beam from a material having high rigidity or heavy material. It is an object of the present invention to provide an electrostatic drive element that can be used, and an electronic device using the same.

The electrostatic drive element according to the present invention includes the following elements (a) to (e), so that the contact can be displaced three-dimensionally, and the effective rigidity of the beam structure changes before and after the contact of the contact. It is what you do. The electronic device according to the present invention includes the electrostatic drive element as a switching element in a signal circuit.
(A) Substrate having a first electrode on the surface (b) Cross-linked beam main body fixed on the substrate, intersecting the beam main body and integrated with the beam main body, and having a first contact near the free end A wing piece portion and a second electrode provided along the extending direction of the wing piece portion, the first contact of the wing piece portion being three-dimensionally displaceable on the side of the doubly supported beam (c) substrate A fulcrum portion (d) provided in the signal circuit having an angle which becomes a base point for deformation of the blade piece portion, and closes the signal circuit by forming a capacitor with the contact with the first contact or with the first contact. Second contact (e) A voltage is applied to the first electrode and the second electrode, and the wing piece is displaced to the substrate side together with the beam body by the generated electrostatic force. Driving means for biasing the first contact in a direction approaching the second contact with the corner as a base point

  In this electrostatic drive element, when an electrostatic force is generated between the first electrode and the second electrode due to voltage application, the entire blade part is displaced to the substrate side together with the beam body, and then a part of the blade part is Deforms with the corner of the support as a fulcrum In other words, the blade part is deformed in such a way that the tip (first contact) approaches the substrate side or moves away from the substrate with the beam body as the rotation axis, and contacts the second contact or forms a capacitance between the contacts. At this time, the tip of the blade piece can be displaced three-dimensionally, and after coming into contact with the fulcrum, the tip of the tip looks like a cantilever and the effective rigidity increases. As a result, the first contact is urged toward the second contact with a certain pressure, and the first contact comes into strong contact while sliding on the second contact. That is, the contact operation between the contacts is effectively softened, and the repulsive force between the contacts is weakened, so that the bounce phenomenon of the contacts is prevented or suppressed, and the stable position is obtained.

  According to the electrostatic drive element of the present invention, a blade piece is provided so as to intersect the both cantilever beams, the first contact is provided at the free end of the blade piece, and the blade piece is deformed on the substrate side. Since the fulcrum portion is provided, the first contact can be given a three-dimensional degree of freedom within the operating range, and the wing piece portion can be effectively increased in rigidity after being deformed by the fulcrum portion. it can. Therefore, the bounce phenomenon at the contact can be prevented or suppressed, and accordingly, the signal loss at the time of input / output is reduced, and the reliability over time is improved. Further, it is not necessary to make the beam structure heavy or thick, and it can be made light and thin, thereby enabling electrostatic driving at a low voltage. Therefore, by providing such an electrostatic drive element as a switching element in an electronic circuit, for example, an electronic device with improved performance and low power consumption can be realized.

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

[First Embodiment]
FIG. 2 shows a planar structure of the electrostatic driving element 1 according to the first embodiment of the present invention, and FIG. 1 shows a cross-sectional structure taken along the line AA of FIG. The electrostatic driving element 1 includes a cantilever beam 20 on a substrate 11 with an insulating film 12 interposed therebetween, and has a first electrode 13 for electrostatic driving so as to face the both cantilever beam 20. The double-supported beam 20 is provided with first contacts 25A and 25B. A signal wiring is provided on the substrate 11 so as to be electrically separated from the first electrode 13 so as to face the first contacts 25A and 25B. For example, as shown in FIG. 2, this signal wiring is composed of a pair of input side wiring 14A and output side wiring 14B, and constitutes a two-division circuit that divides the input high-frequency signal into two. . Contacts (second contacts 14, 14) are provided between the input side wiring 14A and the output side wiring 14B. If the input / output is reversed from that shown in FIG. 2, a mixing circuit for mixing two high-frequency signals can be configured.

  The double-supported beam 20 is obtained by integrating a wing piece portion 23 into a beam main body 21. The wing pieces 23 intersect each other at an intermediate position of the beam body 21, and the planar structure of the entire beam has a substantially cross shape. The beam body 21 has a bridge structure in which both ends are supported by support portions (anchors) 22 respectively. The blade portion 23 forms a horizontal plane with the beam main body 21 at the initial position, but rotates in a certain range around the beam main body 21 when driven by electrostatic force, and its tip (free end) is three-dimensionally. Displaceable.

The substrate 11 is made of a semiconductor material such as silicon (Si). The insulating film 12 electrically separates the doubly supported beam 20 from the substrate 11 and is composed of, for example, a single layer or a plurality of layers of silicon nitride (SiN) or silicon dioxide (SiO ₂ ).

  The first electrode 13 has a cross-sectional shape having a mesa-shaped convex portion 13A in the center. The convex portion 13A is a divided electrode 24B on the second electrode 24 side described later, and the peripheral portion 13B of the convex portion 13A is a divided electrode. 24A and 24C are opposed to each other. That is, the first electrode 13 is narrow between the central divided electrode 24B and wide between the other two divided electrodes 24A and 24C.

  The convex portion 13A of the first electrode 13 also serves as a fulcrum portion of the present invention, and positions corresponding to the corners of both ends function as a fulcrum F for deformation of the blade portion 23. Here, the height of the convex portion 13A is such a height that the first contacts 25A and 25B come into contact with the second contacts 14 and 14 of the signal wiring when the blade piece portion 23 is deformed at the convex portion 13 (fulcrum portion). have. The first electrode 13 is formed of a noble metal such as gold or a conductive material such as a copper alloy, an aluminum alloy, or a tungsten alloy.

An insulating film 15 is provided on the surface of the first electrode 13 in order to prevent direct contact with the doubly supported beam 20. The insulating film 15 is formed of a single layer or a plurality of layers made of, for example, silicon nitride (SiN) or silicon dioxide (SiO ₂ ).

  The double-supported beam 20 is made of an insulating material such as silicon dioxide. A second electrode 24 is provided on the back surface of the blade portion 23 (the surface facing the substrate 11) of the double-supported beam 20 with second contact points 25 </ b> A and 25 </ b> B for signal interruption interposed therebetween.

  The second electrode 24 is composed of a plurality of, for example, three divided electrodes 24A, 24B, and 24C. The divided electrodes 24A to 24C are spaced apart from each other at positions where the beam body 21 of the blade portion 23 is the axis of symmetry. Arranged. The divided electrodes 24A to 24C are formed of a noble metal such as gold or a conductive material such as an aluminum alloy. Here, the divided electrodes 24A to 24C are grounded and have the same potential. For example, the divided electrode 24B and the two divided electrodes 24A and 24C can be electrically separated to have different potentials. On the other hand, a metal film 27 is formed on the surface of the blade piece 23 at a position facing the second electrode 24 and the first contacts 25A and 25B.

  Further, a protective film 26 is provided on the back side of the both-end beam 20 and a protective film 28 is provided on the front side. Further, a plurality of notched grooves (bent portions 29) are provided on the surface of the blade piece portion 23 along the extending direction of the beam main body 21. These bent portions 29 facilitate deformation of the wing piece portion 23 at the fulcrum F due to electrostatic force, and allow the first contacts 25A and 25B to contact the second contact 14 with a constant pressure. Yes.

  The protective film 26 has a function of electrically separating the first electrode 13 and the second electrode 24 and reducing friction of the blade portion 23 during contact. On the other hand, the protective film 28 is for reinforcing the blade piece 23. These protective films 26 and 28 are made of an insulating material such as silicon nitride, for example.

  The metal film 27 reinforces the blade piece 23 and reduces warpage of the blade piece 23 due to stress caused by the film formation process, and is made of the same noble metal or conductive material as the second electrode 24. Yes. In the present embodiment, it is preferable that the rigidity of the blade piece portion 23 is relatively higher than that of the beam body 21 in order to smoothly drive the entire blade piece portion 23. Thus, in order to make the rigidity of the wing piece portion 23 higher than that of the beam main body 21, in addition to providing the metal film 27 larger than the width of the beam main body 21, the width and thickness of the wing piece portion 23 are set to be different from those of the beam main body 21. There is also a method of making it relatively larger than that.

  An electrostatic driving voltage is applied between the first electrode 13 and the second electrode 24 through a direct current power source (DC) as a driving means.

  The first contacts 25A and 25B connect the input side wiring 14A and the output side wiring 14B by contacting the second contacts 14 and 14 by electrostatic force, that is, the signal circuit is “closed”. The signal circuit is "opened" by leaving. The first contacts 25A and 25B are made of, for example, the same material as that of the second electrode 24. In particular, the first contacts 25A and 25B are preferably made of a soft noble metal such as gold in order to reduce an impact at the time of contact. Further, when the first contacts 25A and 25B are driven, they have a three-dimensional degree of freedom in the operating range as described above, and by sliding to the second contact 14, impact upon contact is made. More relaxed, thereby preventing signal loss.

  These first contacts 25A, 25B are also in contact with the second contact 14 and subsequent to the second contact 14 by the attractive force caused by the electrostatic force generated between the first electrode 13 and the second electrode 24 having two kinds of electrode intervals. The pushing operation to the two contacts 14 is continuously performed. Thereby, the stability with respect to the repeated operation | movement of a signal opening / closing can be improved.

  The electrostatic drive element according to the present embodiment is an ohmic type (DC) capable of inputting and outputting a high-frequency signal and direct current (DC) by directly contacting the first contacts 25A and 25B and the second contacts 14 and 14 described above. A capacitive type electrostatic drive element capable of inputting and outputting only high-frequency signals by interposing a dielectric between the first contacts 25A and 25B and the second contact 14. It is good.

  Next, a method for manufacturing the electrostatic driving element 1 will be described.

  4 to 9 show the manufacturing method of the electrostatic driving element 1 in the order of steps. 4 (C), FIG. 5 (B), FIG. 6 (B), FIG. 8 and FIG. 9 for the convenience of explanation, the beam is included in the cross-sectional configuration along the line BB in FIG. The part from the part which cross | intersects the blade piece part 23 of the main body 21 to the support part 22 is expanded and shown in FIG. 4 (A), FIG. 4 (B), FIG. 5 (A), FIG. FIG. 7 shows a cross-sectional configuration along the line AA in FIG.

  First, as shown in FIG. 4A, an insulating film 12 is formed on the surface of a silicon substrate 11. That is, after the silicon thermal oxide film 12A is formed by oxidizing the substrate 11 by, for example, a thermal oxidation method, a silicon nitride film 12B is subsequently formed on the silicon thermal oxide film 12A by, for example, a low pressure CVD (Chemical Vapor Deposition) method. Film. The thicknesses of the silicon thermal oxide film 12A and the silicon nitride film 12B are each 20 nm, for example.

  Subsequently, as shown in FIG. 4B, after depositing a noble metal such as gold or a conductive material such as a copper alloy, an aluminum alloy, or a tungsten alloy on the silicon nitride film 12B by using a sputtering method or the like, By patterning using a photolithography process, a lift-off process, and an etching process, a signal wiring including the first electrode 13 having the convex portion 13A and the second contacts 14 and 14 is formed. After that, an insulating film such as silicon nitride or silicon dioxide is deposited to form an insulating film 15 and patterning to expose the second contact 14.

  On the other hand, as shown in FIG. 4C, a noble metal such as gold or a conductive material such as a copper alloy, an aluminum alloy, or a tungsten alloy is deposited at a position spaced apart from the convex portion 13A in the y-axis direction. Then, the lower support portion 22A of the pair of support portions 22 is formed by patterning. Examples of methods that can be used for this patterning include lift-off and reactive ion etching (RIE). After that, an insulating film such as silicon nitride or silicon dioxide is deposited to form the insulating films 15 and 15A.

  Subsequently, as shown in FIGS. 5A and 5B, polycrystalline silicon or the like is deposited on part of the second contact 14, the insulating films 15 and 15A, and the silicon nitride film 12B by a low pressure CVD method or the like. Thereby, the sacrificial layer 16 is formed.

  Subsequently, as shown in FIGS. 6A and 6B, the upper surface of the sacrificial layer 16 is planarized using CMP (Chemical and Mechanical Polishing), and then a protective film 26 is formed. Then, a part of the upper surface of the conductive film of the lower support portion 22A is exposed by patterning (FIG. 6B).

  Subsequently, as shown in FIG. 7, the blade piece 23 is formed by repeating the process of laminating the constituent materials of each part and patterning, and at the same time, the beam body 21 is formed as shown in FIG. To do.

Subsequently, as shown in FIG. 9, the sacrificial layer 16 is removed using, for example, xenon difluoride (XeF ₂ ). Thereby, the board | substrate 11 provided with the both-ends beam 20 is completed.

  Next, the operation of the electrostatic driving element 1 will be described with reference to FIGS.

  In the present embodiment, as described above, the distance between the first electrode 13 and the second electrode 24 is narrow at the center position corresponding to the beam main body 21, and has a wide structure at both side positions. Therefore, when a voltage is applied between the first electrode 13 and the second electrode 24, first, static electricity is applied to a narrow region between the convex portion 13A of the first electrode 13 and the divided electrode 24B of the second electrode 24. Force works effectively. As a result, the blade piece 23 is displaced horizontally from the initial position toward the substrate 11 and contacts the insulating film 15 on the convex portion 13A (fulcrum portion). In this state, the electrostatic force effectively acts between the peripheral portion 13B of the first electrode 13 and the divided electrodes 24A and 24C of the second electrode 24, so that the blade piece portion 23 is a fulcrum of the insulating film 15. It bends at a position corresponding to F, and the tip is deformed in a direction closer to the substrate 11. That is, the entire wing piece 23 is bent in a convex shape in FIG. As a result, the first contacts 25A and 25B come into contact with the second contacts 14 and 14 with a constant pressure, and the signal circuit is thereby closed. FIG. 3 shows the state at that time.

  Thereafter, when the voltage between the first electrode 13 and the second electrode 24 is cut off, the beam body 21 and the blade piece 23 return to the initial position by the restoring force, and the first contacts 25A and 25B are second. The signal circuit is opened after leaving the contacts 14 and 14.

  As described above, in the present embodiment, the double-supported beam 20 has a structure including the blade portion 23 with respect to the beam main body 21, and contacts (first contacts 25 </ b> A and 25 </ b> B) are provided at the free end of the blade portion 23. Therefore, the first contacts 25A and 25B have a three-dimensional degree of freedom, and when the first contacts 25A and 25B come into contact with the second contacts 14 and 14, it is allowed to skid. Therefore, the repulsive force is weakened between the first contacts 25A, 25B and the second contacts 14, 14, and an effective soft contact operation is performed.

  In addition, since the first electrode 13 on the substrate 11 side is provided with the fulcrum part (convex part 13A) facing the center of the wing piece part 23, the wing piece part 23 is lowered and further deformed with the fulcrum F as a base point. In doing so, the portion ahead of the fulcrum F is like a cantilever beam, and the effective rigidity is increased. Accordingly, the first contacts 25A and 25B are urged toward the second contacts 14 and 14 with a constant pressure, and stable contact is performed in combination with the side slip phenomenon of the first contacts 25A and 25B as described above. Therefore, the conventional bounce phenomenon does not occur between the first contacts 25A and 25B and the second contacts 14 and 14, and signal loss at the time of input / output (opening / closing) is reduced. Improves.

  Further, in the present embodiment, the rigidity of the blade portion 23 can be increased without configuring the entire beam with a heavy material or the like, so that the drive voltage can be kept low and the power consumption can be greatly reduced. Can do.

  Further, since a plurality of bent portions 29 made of notched grooves are provided on the surface of the wing piece portion 23 and the wing piece portion 23 is provided with flexibility, the wing piece portion 23 can be easily deformed. As a result, the drive voltage can be kept low, and the power consumption can be further reduced.

  The example in which the signal circuit including the second contacts 14 and 14 is provided on the substrate 11 has been described as the first embodiment. However, a circuit substrate is provided separately from the substrate 11 and a signal circuit is formed thereon. May be. A specific example will be described below as the second embodiment.

[Second Embodiment]
FIG. 10 illustrates a cross-sectional configuration of the electrostatic driving element 2 according to the second embodiment. FIG. 11 schematically shows a planar structure (the upper substrate is not shown) when the substrate 11 is viewed from the opposite surface side, and FIG. 10 corresponds to a cross section taken along the line CC in FIG. is doing. In addition, the same code | symbol is attached | subjected about the same component as the said embodiment, and the description is abbreviate | omitted.

  In the electrostatic driving element 2, the circuit board 31 is disposed opposite to the board 11, and the cantilever beam 20 exists between the board 11 and the circuit board 31.

  In the double-supported beam 20, the contacts (first contacts 25 </ b> A and 25 </ b> B) are provided on the tip surface side of the blade piece 23 unlike the above-described embodiment. In addition, the configuration of the second electrode 24 is substantially the same as in the first embodiment.

  An insulating film 32 is formed on the surface of the circuit board 31. A signal circuit is formed on the insulating film 32, and second contacts 14 and 14 are provided at positions facing the first contacts 25A and 25B on the both-support beam 20 side of the signal circuit. The configuration of the signal circuit is the same as that in the above embodiment.

  Unlike the first embodiment, the first electrode has a two-layer structure on the substrate 11 side. That is, a flat lower first electrode 33 is provided on the insulating film 12, and a pair of upper first electrodes 35A and 35B are formed on the lower first electrode 33 with insulating layers 34A and 34B interposed therebetween. The lower first electrode 33 is exposed in a central region between the upper first electrodes 35A and 35B, and this exposed region faces the divided electrode 24B on the blade piece 23 side. The lower first electrode 33 and the upper first electrodes 35A and 35B are electrically connected so as to have the same potential here, but they may be separated to have different potentials.

  The end surfaces of the insulating layers 34A and 34B on the central region side are each formed in an L-shaped cross section, and these portions serve as second fulcrum portions 36A and 36B. The corners of these second fulcrum portions 36A and 36B serve as fulcrum F2 when the blade piece 23 is deformed. Further, first fulcrum portions 37A and 37B are provided on the upper first electrodes 35A and 35B respectively so as to be opposed to both ends of the wing piece portion 23, and the corners of these first fulcrum portions 37A and 37B are the wing pieces. This is the fulcrum F1 when the portion 23 is deformed. The exposed regions of the upper first electrodes 35A and 35B that are not covered by the first fulcrum portions 37A and 37B are opposed to the divided electrodes 24A and 24C, respectively. The insulating layers 34A and 34B including the second fulcrum portions 36A and 36B and the first fulcrum portions 37A and 37B are made of an insulating material such as silicon dioxide. The material composition of other elements is the same as that of the first embodiment. In the present embodiment, the lower first electrode 33 and the upper first electrodes 35A and 35B correspond to the first electrode of the present invention, and the first fulcrum portions 37A and 37B and the second fulcrum portions 36A, 36B corresponds to the fulcrum portion of the present invention.

  As described above, in the present embodiment, unlike the first embodiment, the first electrode (lower first electrode 33 and upper first electrodes 35A and 35B) and the second electrode 24 (divided electrodes 24A to 24C) The interval is wide at the center position corresponding to the beam main body 21 and is narrow at the positions on both sides thereof. As a result, the blade portion 23 is deformed so as to bend in a substantially concave shape in FIG. 10 after contacting the first fulcrum portions 37A and 37B and further the second fulcrum portions 36A and 36B by electrostatic force. 25A and 25B are urged toward the second contacts 14 and 14 side of the circuit board 31. Details thereof will be described later.

  Next, an example of a method for manufacturing the electrostatic driving element 2 will be described.

  12 to 17 show the manufacturing method of the electrostatic driving element 2 in the order of steps. Since the electrostatic drive element 2 has a symmetric configuration with the extending direction of the blade piece 23 as the symmetry axis, FIGS. 13A, 13C, and 14B are similar to FIG. Of the cross-sectional configuration along the line D-D, the portion from the portion intersecting the blade portion 23 of the beam body 21 to the support portion 22 is shown in an enlarged manner.

  Following the step shown in FIG. 4A, as shown in FIG. 12A, a noble metal such as gold or a copper alloy, a copper alloy, an aluminum alloy, or a tungsten alloy is formed on the silicon nitride film 12B using a sputtering method or the like. The lower first electrode 33 is formed by depositing a conductive material such as. Next, as shown in FIG. 12B, an insulating material such as silicon dioxide is stacked on the lower first electrode 33 and patterned, and further, the insulating layers 34A and 34B are stacked by stacking the conductive material. The second fulcrum portions 36A and 36B and the upper first electrodes 35A and 35B are formed. Next, as shown in FIG. 12C, the first fulcrum portions 37A and 37B are formed by depositing and patterning the insulating material on the upper first electrodes 35A and 35B. Simultaneously with the step shown in FIG. 12, the lower support portion 22A shown in FIG. 13A is formed. The formation of the lower support portion 22A is the same as in the above embodiment.

  Subsequently, as shown in FIGS. 13B and 13C, the lower first electrode 33, the upper first electrodes 35A and 35B, the insulating layers 34A and 34B, the second fulcrum portion 36, the lower support portion 22A, and A sacrificial layer 38 is formed by depositing polycrystalline silicon or the like on the silicon nitride film 12B by using a low pressure CVD method or the like.

Subsequently, as shown in FIGS. 14A and 14B, the upper surface of the sacrificial layer 38 is planarized using CMP, a protective film 26 is formed, and then patterned to conduct the conductive material of the lower support portion 22A. A part of the upper surface of the film is exposed (FIG. 14B). Subsequently, as shown in FIG. 15, the doubly supported beam 20 is formed by repeating the process of laminating the constituent materials of the constituent parts and the patterning. Subsequently, as shown in FIG. 16, the substrate 11 including the doubly supported beams 20 is completed by removing the sacrificial layer 38 using, for example, XeF ₂ or the like.

  Next, an insulating film 32 is formed over the circuit substrate 31 in the same manner as the substrate 11 illustrated in FIG. Subsequently, as shown in FIG. 17, a noble metal such as gold or a conductive material such as a copper alloy, an aluminum alloy, or a tungsten alloy is deposited at a predetermined position on the insulating film 32 by using, for example, a sputtering method. Then, the second contacts 14 and 14 are formed by patterning.

  Finally, the substrate 11 and the circuit board 31 are bonded together with a spacer in between, whereby the electrostatic driving element 2 shown in FIG. 10 is completed.

  Next, the operation of the electrostatic driving element 2 will be described.

  In the electrostatic driving element 2, when a voltage is applied between the first electrode (lower first electrode 33 and upper first electrodes 35A and 35B) and the second electrode 24 (divided electrodes 24A to 24C), first, The electrostatic force effectively acts on a narrow region between the upper first electrodes 35A and 35B and the divided electrodes 24A and 24C. As a result, the vicinity of both ends of the blade piece portion 23 is horizontally displaced from the initial position toward the substrate, and comes into contact with the first fulcrum portions 37A and 37B. In this state, electrostatic force is effectively applied even in a region where the initial interval between the lower first electrode 33 and the divided electrode 24B on the second electrode 24 side is wide, whereby the wing piece portion 23 has the first fulcrum portion 37A, Curved with each fulcrum F1 of 37B as a base point, the central portion is deformed in a direction closer to the substrate 11, and the first contacts 25A, 25B come into contact with the second contacts 14, 14 on the circuit board 31 side. Further, the blade portion 23 is further attracted to the substrate 11 side to be deformed with the fulcrum F2 of the second fulcrum portions 36A and 36B as a base point, and the first contacts 25A and 25B are pressed against the second contacts 14 and 14 to generate signals. The circuit is closed. FIG. 18 shows the state at that time.

  Thereafter, when the voltage between the lower first electrode 33 and the upper first electrodes 35A and 35B and the second electrode 24 (24A to 24C) is cut off, the beam main body 21 and the blade piece 23 are initialized by the restoring force. At the same time, the first contacts 25A and 25B are separated from the second contacts 14 and 14, and the signal circuit is opened.

  Also in the present embodiment, similar to the first embodiment, by providing the beam main body 21 with the blade portion 23, the repulsive force between the first contacts 25A, 25B and the second contact 14 is weakened, and the contact operation is performed. Is effectively softened, and fulcrum portions (first fulcrum portions 37A and 37B, and further second fulcrum portions 36A and 36B) are provided so that the blade portion 23 is bent in a concave shape at the two fulcrum points F1 and F2. Therefore, the effective rigidity of the blade portion 23 is increased in stages, and the first contacts 25A and 25B come into contact with the second contacts 14 and 14 side with a constant pressure. Therefore, the bounce phenomenon does not occur between the first contacts 25A and 25B and the second contacts 14 and 14, signal loss at the time of input / output (opening / closing) is reduced, and reliability over time is improved. Other functions and effects, and applying an electrostatic force even when the contacts are opened are the same as in the first embodiment.

  In addition, in the present embodiment, the shape of the electrodes (33, 35) on the substrate 11 side is appropriately designed, and the upper first electrodes 35A, 35B are driven independently of each other, whereby Of the first contacts 25A and 25B can be independently driven. Such independent driving of the first contacts 25A and 25B enables control of two channels with one element.

  In the above embodiment, the first contacts 25A and 25B are separated from the second contacts 14 and 14 by the restoring force of the beam structure itself, but at this time, the electrostatic force is applied in the same manner as in the contact. You may do it. That is, after the voltage application between the first electrodes 33 and 35 and the second electrode 24 is cut off and the contacts 25A and 25B are separated from the second contacts 14 and 14, a voltage that is weaker than that at the time of closing is applied. The voltage is applied between the first electrode 35 and the second electrodes 24A and 24C. As a result, an electrostatic force weaker than that at the time of contact is applied and the shape of the blade piece 23 is restored, and the shape is drawn toward the substrate 11, and the first contacts 25A and 25B and the second contacts 14 and 14 are shifted to the open state. To be able to.

  The electrostatic drive element 2 is mounted on a wafer package 40 including an upper substrate 41 and a lower substrate 42 as shown in FIG. The upper substrate 41 and the lower substrate 42 are provided with signal wirings 43A and 43B on opposite surfaces, respectively, and a certain space is secured between the substrates by a spacer 44. Here, the lower substrate 42 corresponds to the substrate 11, the upper substrate 41 corresponds to the circuit substrate 31, and the region surrounded by the alternate long and short dash line is the drive unit 45 including the doubly supported beam 20. The upper substrate 41 and the lower substrate 42 are fixed by a wafer adhesive layer 46.

  On the other hand, in the case of the electrostatic drive element 1 according to the first embodiment, it can be mounted not only on the wafer package 40 but also on various other packages such as a hermetic package.

  Next, a communication device will be described as an example of an electronic device including an electrostatic drive element. 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. 20 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 elements 1 and 2 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.

  Thus, by applying the electrostatic drive elements 1 and 2 to the communication device, the reliability is high and the power consumption can be reduced.

  In the communication apparatus shown in FIG. 20, the case where the electrostatic drive element is applied to the transmission / reception switch 101 has been described. However, the present invention is not necessarily limited to this and may be applied to other signal switches. .

  The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and the specific configuration of the electrostatic drive element and the electronic device and the procedure for the manufacturing method thereof are described. The embodiment can be freely modified as long as the same effects as those of the above embodiment can be obtained.

  For example, in the second embodiment, the configuration of the electrostatic driving element 2 is such that the first substrate and the second substrate are arranged to face each other, but it is configured by only one substrate using a deep etching technique. An electrostatic drive element that drives 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 the top view which showed typically the electrostatic drive element shown in FIG. It is sectional drawing for demonstrating the drive means 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. FIG. 8 is a cross-sectional view for explaining a step following the step in FIG. 7. 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 the top view which showed typically 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 2nd Embodiment of this invention. It is sectional drawing for demonstrating the process following FIG. It is sectional drawing for demonstrating the process following FIG. It is sectional drawing for demonstrating the process following FIG. FIG. 16 is a cross-sectional view for illustrating a process following the process in FIG. 15. FIG. 17 is a cross-sectional view for illustrating a process following the process in FIG. 16. It is sectional drawing for demonstrating the drive means of the electrostatic drive element shown in FIG. It is sectional drawing when the electrostatic drive element shown in FIG. 10 is packaged. 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 1, 2 ... Electrostatic drive element, 11 ... 1st board | substrate, 12, 15, 15A, 32 ... Insulating film, 12A ... Silicon thermal oxide film, 12B ... Silicon nitride film, 13 ... 1st electrode, 13A ... Projection part, 13B ... peripheral part, 14 ... second contact, 14A ... input-side wiring, 14B ... output-side wiring, 16, 38 ... sacrificial layer, 20 ... both supported beams, 21 ... beam main body, 22 ... supporting portion, 22A ... bottom side Support part, 23 ... Wing piece part, 24 ... Second electrode, 24A-24C ... Split electrode, 25A, 25B ... First contact, 26, 28 ... Protective film, 27 ... Metal film, 29 ... Bent part, 31 ... Circuit Substrate, 33 ... lower first electrode, 34A, 34B ... insulating layer, 35A, 35B ... upper first electrode, 36 ... second fulcrum, 37A, 37B ... first fulcrum, 40 ... wafer package, 41 ... upper substrate 42 ... Lower substrate, 43A, 43B ... Wiring, 44 (44A, 4 B) ... spacer 45 ... drive unit, 46 ... wafer bonding layer, 101 ... reception switcher (electrostatic drive element), 102 ... high-frequency filter, 103 ... antenna, F, F1, F2 ... fulcrum

Claims (10)

A substrate having a first electrode on the surface;
A cross-linked beam main body fixed on the substrate, a wing piece section that intersects the beam main body and is integrated with the beam main body and has a first contact in the vicinity of a free end, and an extending direction of the wing piece section A doubly-supported beam including a second electrode provided along the first contact point of the blade portion, the first contact of the blade piece being displaceable three-dimensionally;
A fulcrum portion provided on the substrate side and having an angle serving as a base point of deformation of the blade piece portion;
A second contact that is provided in the signal circuit and closes the signal circuit by forming a capacitor with the first contact or with the first contact;
A voltage is applied to the first electrode and the second electrode, and the wing piece portion is displaced together with the beam body toward the substrate side by the generated electrostatic force, and then the tip of the wing piece portion is positioned at the corner of the fulcrum portion. An electrostatic drive element comprising: drive means for biasing the first contact in a direction approaching the second contact from the base point. The electrostatic drive element according to claim 1, wherein a distance between the second electrode and the first electrode is different between a central position corresponding to the beam body and positions on both sides thereof. The fulcrum portion is provided at a position corresponding to the beam main body on the substrate, the second contact is provided on the substrate, and an interval between the first electrode and the second electrode corresponds to the beam main body. The electrostatic drive element according to claim 2, wherein the electrostatic drive element is narrow at a central position where the power is applied and wide at positions on both sides thereof. The first electrode has a convex portion that also serves as the fulcrum portion, and the surface is covered with an insulating film, and the second electrode is composed of three divided electrodes, and each of the divided electrodes has the beam body as an axis of symmetry. Spaced apart in position,
The electrostatic drive element according to claim 3, wherein a distance from the first electrode is narrow in the central divided electrode and wide in the other two divided electrodes. The convex portion of the first electrode has a certain capacity when the first contact contacts the second contact when the wing piece is deformed by the convex after the wing piece is displaced by electrostatic force. The electrostatic driving element according to claim 4, wherein the electrostatic driving element has a height to be formed. The electrostatic drive element according to claim 1, further comprising: a bent portion formed by a notch groove formed along the extending direction of the beam main body on a surface of the blade piece portion. A circuit board is provided at a position facing the board with the both cantilever beams in between, the second contact is provided on the circuit board, and the first contact faces the second contact of the blade portion. 2. The electrostatic device according to claim 1, wherein a gap between the second electrode and the first electrode is wide at a central position corresponding to the beam main body and is narrow at positions on both sides thereof. Drive element. The second electrode is composed of three divided electrodes, and the divided electrodes are spaced apart from each other with the beam body as the axis of symmetry, and the first electrode has a lower first electrode and an upper first electrode. It is composed of electrodes and
The lower first electrode is disposed at a position facing the center divided electrode of the second electrode, and the upper first electrode is disposed at a position facing the divided electrodes on both sides of the second electrode, respectively.
The electrostatic drive element according to claim 7, wherein a distance between the central divided electrode and the lower first electrode is wide, and a distance between the other two divided electrodes and the upper first electrode is narrow. As the fulcrum portions, a pair of first fulcrum portions are disposed on the upper first electrode so as to be spaced apart from each other, and a pair of second fulcrum portions are spaced apart from each other on the lower first electrode. The electrostatic driving element according to claim 8, wherein two fulcrum portions are arranged. An electronic device including an electrostatic drive element, wherein the electrostatic drive element is
A substrate having a first electrode on the surface;
A cross-linked beam main body fixed on the substrate, a wing piece section that intersects the beam main body and is integrated with the beam main body and has a first contact in the vicinity of a free end, and an extending direction of the wing piece section A doubly-supported beam including a second electrode provided along the first contact point of the blade portion, the first contact of the blade piece being displaceable three-dimensionally;
A fulcrum portion provided on the substrate side and having an angle serving as a base point of deformation of the blade piece portion;
A second contact that is provided in the signal circuit and closes the signal circuit by forming a capacitor with the first contact or with the first contact;
A voltage is applied to the first electrode and the second electrode, and the wing piece portion is displaced together with the beam body toward the substrate side by the generated electrostatic force, and then the tip of the wing piece portion is positioned at the corner of the fulcrum portion. An electronic device comprising: drive means for energizing the first contact in a direction approaching the second contact with reference to the base point.

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