JP2010067587A - Mems switch element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress signal decay, and to improve productivity. <P>SOLUTION: A variable capacitive element 1 is formed by using a silicon substrate 4 sandwiched by first and second substrates 2, 3. A support part 5, a movable part 6, a support beam 7, and an inclination part 8 are formed on the silicon substrate 4. First and second movable side metal electrodes 9, 10 are formed evenly on both sides of the silicon substrate 4. A portion of the first movable side metal electrode 9 formed on the movable part 6 serves as a movable side signal electrode 13 and faces a fixed-side signal electrode 15 arranged on the substrate 2. A portion of the second movable side metal electrode 10 formed on the movable part 6 serves as a movable side drive electrode 14, and faces a fixed side drive electrode 16 arranged on the substrate 3. The first and second movable side metal electrodes 9, 10 are press-bonded to the fixed side metal electrodes 19, 20 arranged on the substrates 2, 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a MEMS switch element in which a movable part that can be displaced in a thickness direction is formed by processing a silicon substrate, and a manufacturing method thereof.

  In general, a MEMS (microelectromechanical systems) switching element such as a variable capacitance element or a relay element is known in which a movable part that can be displaced in the thickness direction is formed by processing a silicon substrate. In a sensor having such a movable part, for example, a silicon substrate is sandwiched between two glass substrates, and a support part fixed to the glass substrate is formed on the silicon substrate, and the support part is movable via a support beam. It is the structure which supports a part so that a displacement is possible (for example, refer patent document 1, 2).

  Here, in the acceleration sensor described in Patent Document 1, a fixed electrode is provided at a position facing the movable portion of the glass substrate, and the capacitance between the movable portion and the fixed electrode is detected, thereby detecting the capacitance. It is configured to detect the applied acceleration.

  Further, an anodic bonding method is generally used for bonding the glass substrate and the silicon substrate. However, since a large potential difference occurs between the glass substrate and the silicon substrate during anodic bonding, the movable part may stick to the glass substrate due to this potential difference. In view of this point, Patent Document 2 discloses a configuration in which a metal thin film is provided between a glass substrate and a silicon substrate, and the glass substrate and the silicon substrate are bonded by pressure bonding these metal thin films. Has been.

JP-A-5-172846 JP 2007-69320 A

  By the way, in the sensor described in Patent Documents 1 and 2 described above, the movable portion is formed of a conductive silicon material, and the capacitance between the movable portion and the fixed electrode provided on the glass substrate is detected. It has become. Here, in order to electrically connect the movable part to an external processing circuit, it is necessary to provide an extraction electrode made of a conductive metal such as gold (Au) on a silicon material. At this time, since gold and silicon (Si) have poor adhesion, chromium (Cr) is inserted between them as an intermediate layer. However, since the contact resistance between silicon and chromium is large, the detection signal tends to be attenuated, and the detection sensitivity and detection accuracy tend to decrease. In particular, when a high-frequency signal such as a microwave or a millimeter wave is transmitted to the fixed electrode, there is a problem that the loss of the high-frequency signal is large due to the contact resistance between silicon and chromium.

  Moreover, in the sensor of patent document 2, it is set as the structure which provides the metal thin film for joining separately from an extraction electrode. For this reason, it is necessary to form the extraction electrode and the metal thin film for bonding separately, and there is a problem that the manufacturing process is complicated and productivity is lowered.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a MEMS switch element capable of suppressing signal attenuation and improving productivity and a manufacturing method thereof. There is to do.

  In order to solve the above-described problems, the present invention provides a silicon substrate sandwiched between first and second substrates, a support portion formed on the silicon substrate and fixed to the first and second substrates, A movable portion formed on the silicon substrate and supported by the support portion so as to be displaceable in the thickness direction using a support beam, and a position provided on the first substrate and facing the movable portion of the silicon substrate. The present invention is applied to a MEMS switch element that includes a fixed-side signal electrode that is disposed and a fixed-side drive electrode that is provided on the second substrate and is disposed at a position facing the movable portion of the silicon substrate.

  A feature of the configuration adopted by the invention of claim 1 is that the silicon substrate is formed such that a thickness dimension of the support beam is smaller than a thickness dimension of the support portion and the movable portion. The thickness of the silicon substrate is formed by forming an inclined portion whose thickness dimension is gradually reduced from the support portion toward the support beam and an inclined portion whose thickness dimension is gradually reduced from the movable portion toward the support beam. A conductive metal material is attached to both sides of the direction from the vertical direction with respect to both sides of the silicon substrate by vapor deposition or sputtering, so that the first and second substrates facing the first and second substrates are disposed. Two movable-side metal electrodes are formed, and first and second insulating films are provided between the silicon substrate and the first and second movable-side metal electrodes, respectively, and the first movable side is provided. The metal electrode includes a fixed-side signal electrode among the movable parts. A movable-side signal electrode is formed that is located in an opposite position and is close to or away from the fixed-side signal electrode, and the second movable-side metal electrode is opposed to the fixed-side drive electrode in the movable portion. A movable drive electrode for forming an electrostatic force between the fixed drive electrode and the fixed drive electrode is formed on the first substrate, and the first substrate is electrically conductive with the first movable metal electrode. A first fixed-side metal electrode made of a metal material is formed, and the first movable-side metal electrode and the first fixed-side metal electrode are pressure-bonded and joined to the second substrate. Forming a second fixed-side metal electrode made of a conductive metal material that is in contact with the movable-side metal electrode, and press-bonding the second movable-side metal electrode and the second fixed-side metal electrode, The fixed drive electrode is disposed between the fixed drive electrode and the movable drive electrode. A stopper for preventing contact with the movable side drive electrode is provided, the first substrate is provided with a signal via hole electrically connected to the fixed side signal electrode, and the second substrate is provided with the above-mentioned A driving via hole electrically connected to the fixed driving electrode and another driving via hole electrically connected to the second fixed metal electrode are provided.

  A feature of the configuration adopted by the invention of claim 2 is that the silicon substrate is formed such that a thickness dimension of the support beam is smaller than a thickness dimension of the support portion and the movable portion. An inclined portion whose thickness dimension is gradually reduced from the support portion toward the support beam is formed, and the movable portion is in a state before the support portion is fixed to the first substrate than the back surface of the support portion. It protrudes toward the first substrate and is formed in a shape that is recessed from the surface of the support part. On both surfaces of the silicon substrate in the thickness direction, both surfaces of the silicon substrate are formed by vapor deposition or sputtering. On the other hand, by attaching a conductive metal material from the vertical direction, first and second movable-side metal electrodes facing the first and second substrates are formed, respectively, and the silicon substrate and the first and first substrates are formed. Between the two movable metal electrodes, Each of the first movable-side metal electrodes is located in a portion of the movable portion facing the fixed-side signal electrode and is close to and away from the fixed-side signal electrode. A signal electrode is formed, and the second movable-side metal electrode is positioned at a portion of the movable portion facing the fixed-side drive electrode to act on the electrostatic force between the fixed-side drive electrode. A movable drive electrode is formed, and a first fixed metal electrode made of a conductive metal material in contact with the first movable metal electrode is formed on the first substrate, and the first movable electrode is formed. A second fixed-side metal electrode made of a conductive metal material that is in contact with the second movable-side metal electrode and is bonded to the second metal electrode by pressure bonding. And the second movable metal electrode and the second fixed side A stopper for preventing contact between the fixed side drive electrode and the movable side drive electrode is provided between the fixed side drive electrode and the movable side drive electrode, and is attached to the first substrate. Provides a signal via hole electrically connected to the fixed-side signal electrode, and the second substrate has a drive via hole electrically connected to the fixed-side drive electrode and the second via Another driving via hole electrically connected to the fixed side metal electrode is provided.

  According to a third aspect of the present invention, the first and second movable metal electrodes are formed over the entire surface of the silicon substrate, and the first and second insulating films are formed on both surfaces of the silicon substrate. The second movable side metal electrode is formed over the entire surface, and the first movable side metal electrode and the fixed side signal electrode are set to have a thickness dimension larger than the thickness of the skin due to the propagating high frequency signal. The thickness dimension is set to a value that cancels out the warp generated in the movable part due to the difference in the linear expansion coefficient between the first movable metal electrode and the silicon substrate.

  According to a fourth aspect of the present invention, another stopper is provided between the fixed signal electrode and the movable signal electrode to prevent the fixed signal electrode and the movable signal electrode from being in electrical contact with each other. It is said.

  According to a fifth aspect of the present invention, a contact portion made of a conductive material is provided between the fixed-side signal electrode and the movable-side signal electrode to electrically contact the fixed-side signal electrode and the movable-side signal electrode. It is said.

  According to a sixth aspect of the present invention, a silicon substrate sandwiched between the first and second substrates, a support portion formed on the silicon substrate and fixed to the first and second substrates, and formed on the silicon substrate. A movable portion supported by the support portion so as to be displaceable in the thickness direction using a support beam; and a fixed-side signal electrode provided on the first substrate and disposed at a position facing the movable portion of the silicon substrate; A MEMS switch element manufacturing method comprising: a fixed drive electrode provided on the second substrate and disposed at a position facing the movable portion of the silicon substrate, wherein the MEMS switch element is anisotropic A step of forming an indented portion that is recessed from the surface of the remaining portion of the silicon substrate in a portion corresponding to the movable portion and the support beam and protruding from the back surface of the remaining portion; Etching treatment Conducting from the direction perpendicular to both sides of the silicon substrate using a vapor deposition method or a sputtering method on both sides in the thickness direction of the silicon substrate Forming a first and second movable-side metal electrodes facing the first and second substrates by attaching a metal material; and forming the fixed-side signal electrodes on the first substrate. Forming a first fixed-side metal electrode made of a conductive metal material in contact with the first movable-side metal electrode; forming the fixed-side drive electrode on the second substrate; and Forming a second fixed-side metal electrode made of a conductive metal material in contact with the two movable-side metal electrodes, and a first movable-side metal electrode of the first substrate and a first movable of the silicon substrate A step of pressure bonding the side metal electrode, and the second It has a configuration comprising a step of compression bonding and a second movable side metal electrodes of the silicon substrate and the second fixed-side metal electrode plate.

  In the invention of claim 7, in the step of pressure bonding the first fixed side metal electrode of the first substrate and the first movable side metal electrode of the silicon substrate, A protective member for protecting the second fixed metal electrode is provided on the opposite surface side, and the silicon substrate is pressed toward the first substrate through the protective member.

  According to the first aspect of the present invention, since the first and second movable-side metal electrodes are formed on both surfaces of the silicon substrate in the thickness direction, the first movable-side metal electrode is disposed on the movable portion. The movable side signal electrode that is close to and away from the fixed side signal electrode can be formed using the portion that has been fixed, and the fixed side drive can be performed using the portion disposed in the movable portion of the second movable side metal electrode. It is possible to form a movable-side signal electrode that applies an electrostatic force between the electrodes. For this reason, since the movable part can be displaced in the thickness direction by applying a voltage between the fixed drive electrode and the movable signal electrode, the fixed signal electrode and the movable electrode can be moved according to the displacement of the movable part. A variable capacitance element in which the capacitance with the side signal electrode changes can be configured. Thereby, the variable capacitance element can switch the high frequency signal which propagates a signal electrode according to a capacitance change. If the fixed signal electrode and the movable signal electrode can be electrically connected, a switch element that switches between contact and non-contact between the two electrodes according to the displacement of the movable part is configured. Can do.

  In addition, since the movable side signal electrode and the movable side drive electrode are formed using the first and second movable side metal electrodes, the first and second fixed members bonded to the first and second movable side metal electrodes by pressure bonding are used. The movable signal electrode and the movable drive electrode can be electrically connected to an external processing circuit or the like through the side metal electrode. For this reason, since it is possible to transmit the detection signal and apply the drive signal to the outside without using silicon, it is possible to suppress the signal attenuation, reduce the conductor loss in the capacitance detection, and reduce the switching time. Shortening and the like can be achieved.

  Further, since the first and second fixed-side metal electrodes that are in contact with the first and second movable-side metal electrodes are formed on the first and second substrates, the first and second movable-side metal electrodes and The silicon substrate can be fixed between the first and second substrates by pressure bonding the first and second fixed metal electrodes. Therefore, the fixed metal electrode can be bonded by pressure bonding using a part of the first movable metal electrode serving as the movable signal electrode and the second movable metal electrode serving as the movable drive electrode. Compared with the case where a metal thin film is separately provided, the manufacturing process can be simplified and the productivity can be increased.

  In addition, the first and second movable-side metal electrodes and the first and second fixed-side metal electrodes are pressure-bonded to each other, thereby defining a sealed space for accommodating the movable portion between the first and second substrates. Can be made. At this time, since the sealed space can be sealed in an airtight state, by performing pressure bonding in a reduced pressure atmosphere, the air resistance of the movable portion can be reduced and the responsiveness can be improved.

  Since the first and second insulating films are provided between the silicon substrate and the first and second movable-side metal electrodes, the first and second insulating films are used to form the first and second insulating films. It is possible to insulate between the two movable metal electrodes. For this reason, since the first and second movable metal electrodes can have separate functions, the first movable metal electrode can be used to form a movable signal electrode used for capacitance detection and the like. A movable drive electrode for applying an electrostatic force to the movable part can be formed by the side metal electrode.

  Further, since the silicon substrate is formed with a thickness dimension of the support beam smaller than that of the support portion and the movable portion, the movable portion can be easily displaced by reducing the spring constant of the support beam. In addition, the silicon substrate is formed with an inclined portion whose thickness dimension is gradually reduced from the support portion toward the support beam and an inclined portion whose thickness dimension is gradually reduced from the movable portion toward the support beam. No step is formed between the portion and the support beam or between the movable portion and the support beam. That is, the front and back surfaces of the silicon substrate are smoothly continuous. For this reason, for example, when the first and second movable metal electrodes are formed on both sides of the silicon substrate by using vapor deposition or sputtering, the conductive metal material adheres to the both sides of the silicon substrate from the vertical direction. While the metal electrode is not formed on the end surface of the silicon substrate (the side surface of the support beam, etc.), the first and second movable metal electrodes are reliably electrically connected between the support portion and the movable portion and the support beam. Can be connected. Thereby, the disconnection does not occur in the middle of the first and second movable-side metal electrodes, and the first and second movable-side metal electrodes can be reliably formed on both surfaces of the silicon substrate.

  Furthermore, since a stopper is provided between the fixed drive electrode and the movable drive electrode, the stopper can prevent contact between the fixed drive electrode and the movable drive electrode, and they are electrically short-circuited. Can be prevented.

  The invention of claim 2 has the same configuration as that of the invention of claim 1, and therefore has the same effect as that of the invention of claim 1. In addition, since the inclined portion whose thickness dimension is gradually reduced from the support portion toward the support beam is formed in the silicon substrate, no step is formed between the support portion and the support beam. The surface of is smoothly and continuously. For this reason, when the second movable metal electrode is formed on the surface of the silicon substrate by using, for example, vapor deposition or sputtering, the metal electrode is not formed on the end surface of the silicon substrate (side surface of the support beam, etc.) Thus, the second movable-side metal electrode can be reliably electrically connected between the support portion and the movable portion. Thereby, the disconnection does not occur in the middle of the second movable metal electrode, and the second movable metal electrode can be reliably formed on the surface of the silicon substrate.

  Further, since the movable portion is formed in a shape protruding toward the first substrate from the back surface of the support portion, the support beam that presses the movable portion against the first substrate as the protrusion size of the movable portion increases. Spring force increases. For this reason, the spring force of the support beam can be adjusted according to the projecting dimension of the movable part.

  Further, since the movable portion protrudes toward the first substrate, there is no need to protrude toward the second substrate, and the surface of the movable portion is recessed toward the first substrate rather than the surface of the support portion. For this reason, when the silicon substrate is pressure-bonded to the first substrate, even when the silicon substrate is pressed against the first substrate using a pressure jig, the movable portion is more than the first substrate. It will not protrude toward the side. As a result, the movable part does not come into contact with the pressing jig, and damage to the movable part and the movable drive electrode can be prevented.

  According to the invention of claim 3, the first and second movable-side metal electrodes are respectively formed over the entire surface on both surfaces of the silicon substrate in the thickness direction. For this reason, when the metal thin film to be the first and second movable-side metal electrodes is formed on the silicon substrate, it is not necessary to pattern the metal thin film and can be used as it is as the first and second movable-side metal electrodes. it can. Therefore, the manufacturing process can be simplified and the productivity can be improved.

  Further, the thickness dimensions of the first movable-side metal electrode and the fixed-side signal electrode were set to values larger than the skin depth (skin depth) due to the propagating high-frequency signal. Here, when a high-frequency signal propagates, a skin effect occurs in the first movable metal electrode and the fixed signal electrode, and current flows concentrated on the surfaces of the first movable metal electrode and the fixed signal electrode. . At this time, the thickness of the skin where the amplitude of the high-frequency signal is 1 / e of the surface value changes according to the frequency of the high-frequency signal, and becomes thinner as the frequency increases. In the present invention, since the thickness dimension of the first movable-side metal electrode and the fixed-side signal electrode is set to a value larger than the thickness of the skin, the first movable-side metal electrode and the fixed signal electrode are within a range in which transmission loss does not increase. The side signal electrode can be formed thin.

  Further, the thickness dimension of the second movable side metal electrode is set so that the warp occurring in the movable part due to the difference in linear expansion coefficient between the first movable side metal electrode and the silicon substrate is offset. is doing. Thereby, even when the temperature change occurs in the MEMS switch element, it is possible to suppress the warp of the movable part or the like accompanying the temperature change. As a result, for example, the maximum value, the minimum value, the change width, etc. of the capacitance between the movable side signal electrode and the fixed side signal electrode are suppressed in temperature fluctuation, so that these stability against temperature change can be improved. Can do.

  According to the invention of claim 4, since another stopper is provided between the fixed-side signal electrode and the movable-side signal electrode, the stopper can prevent contact between the fixed-side signal electrode and the movable-side signal electrode. it can. Accordingly, the capacitance between the fixed signal electrode and the movable signal electrode is selectively changed between the maximum value and the minimum value according to the proximity and separation between the fixed signal electrode and the movable signal electrode. For this reason, for example, a high frequency signal propagating through the signal electrode can be connected and cut off according to the capacitance, and a switch element (variable capacitance element) for high frequency signals can be configured.

  According to the invention of claim 5, since the contact portion made of a conductive material is provided between the fixed-side signal electrode and the movable-side signal electrode, the fixed-side signal electrode and the movable-side signal electrode are electrically connected by the contact portion. Can be connected. Thereby, these connection and interruption | blocking can be selectively switched according to the proximity | contact and separation | spacing of a stationary-side signal electrode and a movable-side signal electrode. For this reason, for example, a DC signal type switching element can be configured.

  According to the invention of claim 6, since the anisotropic etching process of the silicon substrate is performed, and the recessed portion which is recessed from the remaining portion is formed in the portion corresponding to the movable portion and the support beam in the silicon substrate, the recessed portion An obliquely inclined wall surface can be formed around the. For this reason, when the recess is etched to form the support part, the support beam and the movable part, an inclined part whose thickness is gradually reduced from the support part to the support beam is formed on the surface of the silicon substrate. can do.

  At this time, no step is formed between the support portion and the support beam, and for example, the surface of the silicon substrate is in a smoothly continuous state. For this reason, when the second movable-side metal electrode is formed on the surface of the silicon substrate by vapor deposition or sputtering, no metal electrode is formed on the end surface (side surface of the support beam, etc.) of the silicon substrate. The second movable side metal electrode can be reliably electrically connected between the support portion and the movable portion and the support beam. Thereby, the disconnection does not occur in the middle of the second movable metal electrode, and the second movable metal electrode can be reliably formed on the surface of the silicon substrate.

  Moreover, since the hollow part protrudes toward the back side from the remaining part corresponding to the support part, when the movable part is formed by the hollow part, the movable part protrudes toward the first substrate rather than the support part. . At this time, as the projecting dimension of the movable portion increases, the spring force of the support beam that presses the movable portion against the first substrate increases. For this reason, the spring force of a support beam can be adjusted according to the protrusion dimension of a hollow part.

  Furthermore, since the movable portion protrudes toward the first substrate, it is not necessary to protrude toward the second substrate, and the surface of the movable portion is recessed toward the first substrate rather than the surface of the support portion. For this reason, when the silicon substrate is pressure-bonded to the first substrate, even when the silicon substrate is pressed against the first substrate using a pressure jig, the movable portion is more than the support portion. It will not protrude toward the side. As a result, the movable part does not come into contact with the pressing jig, and damage to the movable part and the movable drive electrode can be prevented.

  According to the invention of claim 7, in the step of pressure bonding the first fixed side metal electrode of the first substrate and the first movable side metal electrode of the silicon substrate, the protective member is provided on the surface side of the silicon substrate. And the silicon substrate is pressed toward the first substrate through the protective member. For this reason, the second movable-side metal electrode of the silicon substrate can be protected using the protective member, and damage, irregularities, and the like are not formed on the second movable-side metal electrode. Thus, even when the second substrate is pressure bonded after the first substrate is pressure bonded, the second movable side metal electrode of the silicon substrate is held in a flat state while the second of the second substrate is held. It is possible to press-bond to the fixed metal electrode of the metal plate, and to prevent poor bonding.

It is a longitudinal cross-sectional view which shows the variable capacitance element by the 1st Embodiment of this invention. It is the top view which looked at the 1st board | substrate from the arrow II-II direction in FIG. It is the top view which looked at the 1st board | substrate and the silicon substrate from the arrow III-III direction in FIG. It is the bottom view which looked at the 2nd board | substrate from the arrow IV-IV direction in FIG. It is a longitudinal cross-sectional view similar to FIG. 1 which shows the state which the movable part displaced by the electrostatic force. It is a longitudinal cross-sectional view which shows the state which formed the recessed part in the silicon substrate by the anisotropic etching process. It is a longitudinal cross-sectional view which shows the state which formed the silicon oxide film on the silicon substrate by the insulating film formation process. It is a longitudinal cross-sectional view which shows the state which formed the support part, the movable part, the support beam, and the inclination part by the movable part formation process. It is a longitudinal cross-sectional view which shows the state which formed the metal thin film in the silicon substrate by the movable side metal electrode formation process. It is a longitudinal cross-sectional view which shows the state which formed the fixed side signal electrode etc. in the glass substrate by the 1st board | substrate formation process. It is a longitudinal cross-sectional view which shows the state which pressure-bonds a silicon substrate to a 1st board | substrate by the 1st board | substrate joining process. It is a longitudinal cross-sectional view which shows the state which formed the fixed side drive electrode etc. in the glass substrate by the 2nd board | substrate formation process. It is a longitudinal cross-sectional view which shows the state which crimp-bonds a 2nd board | substrate to a silicon substrate by the 2nd board | substrate joining process. It is sectional drawing which shows the switch element by 2nd Embodiment. It is the top view which looked at the 1st board | substrate from the arrow XV-XV direction in FIG. It is sectional drawing which shows the relay element by 3rd Embodiment. It is a longitudinal cross-sectional view which shows the switch element by 4th Embodiment. It is the top view which looked at the 1st board | substrate and the silicon substrate from the arrow XVIII-XVIII direction in FIG. It is a longitudinal cross-sectional view which shows the state which formed the hollow part in the silicon substrate by the anisotropic etching process. It is a longitudinal cross-sectional view which shows the state which removed the thermal oxide film for masks from the silicon substrate. It is a longitudinal cross-sectional view which shows the state which formed the thin part in the silicon substrate by the thin part formation process. It is a longitudinal cross-sectional view which shows the state which formed the support part, the movable part, the support beam, and the inclination part by the movable part formation process. It is a longitudinal cross-sectional view which shows the state which formed the insulating film in the silicon substrate by the insulating film formation process. It is a longitudinal cross-sectional view which shows the state which formed the metal thin film in the silicon substrate by the movable side metal electrode formation process. It is a longitudinal cross-sectional view which shows the state which formed the fixed side signal electrode etc. in the glass substrate by the 1st board | substrate formation process. It is a longitudinal cross-sectional view which shows the state which pressure-bonds a silicon substrate to a 1st board | substrate by the 1st board | substrate joining process. It is a longitudinal cross-sectional view which shows the state which formed the fixed side drive electrode etc. in the glass substrate by the 2nd board | substrate formation process. It is a longitudinal cross-sectional view which shows the state which crimp-bonds a 2nd board | substrate to a silicon substrate by the 2nd board | substrate joining process. It is a longitudinal cross-sectional view which shows the variable capacitance element by a 1st modification. It is a longitudinal cross-sectional view which shows the variable capacitance element by a 2nd modification.

  Hereinafter, a MEMS switch device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  First, FIG. 1 to FIG. 13 show a first embodiment. In this embodiment, a variable capacitance element will be described as an example of a MEMS switch element.

  In the drawing, the variable capacitance element 1 is formed by first and second substrates 2 and 3 and a silicon substrate 4 sandwiched between the substrates 2 and 3. Here, the substrates 2 and 3 are made of, for example, an insulating glass material or the like, and are formed in a square shape having a size of about several millimeters.

  The substrates 2 and 3 and the silicon substrate 4 extend in the horizontal direction, for example, along the X axis and the Y axis, when the three axis directions orthogonal to each other are taken as the X axis, the Y axis, and the Z axis. Further, a recessed portion 3 </ b> A that is recessed in a substantially rectangular shape is formed on the back surface side of the second substrate 3. As a result, a sealed space is defined between the substrates 2 and 3 so as to accommodate the movable portion 6 described later at a position corresponding to the recessed portion 3A.

  On the other hand, the silicon substrate 4 is formed using single crystal silicon. And the support part 5, the movable part 6, and the support beam 7 which are mentioned later are formed in the silicon substrate 4 using micromachining technology.

  The support portion 5 is formed on the silicon substrate 4 and is fixed to the first and second substrates 2 and 3. The support portion 5 is formed in a rectangular frame shape that extends along the peripheral edges of the substrates 2 and 3, for example, and surrounds the movable portion 6, the support beam 7, and the like. Here, two beam connecting portions 5 </ b> A located on both sides in the X-axis direction with the movable portion 6 interposed therebetween are provided inside the support portion 5. The support portion 5 has a thickness dimension of about 200 to 300 μm, for example, and holds a sealed space in which the movable portion 6 is disposed between the substrates 2 and 3.

  The movable part 6 is formed on the silicon substrate 4 and supported by the support part 5 using a support beam 7 described later. The movable portion 6 is disposed at a position facing the recessed portion 3A of the substrate 3 and is displaceable in the thickness direction (Z-axis direction). Here, the movable part 6 is formed in a rectangular flat plate shape and has a thickness dimension (for example, about 200 to 300 μm) that is approximately the same as that of the support part 5. The movable portion 6 is formed together with the support portion 5 and the support beam 7 by performing anisotropic etching or the like on the silicon substrate 4.

  The movable portion 6 is displaced in the vertical direction (Z-axis direction) by an electrostatic force generated between drive electrodes 14 and 16 to be described later, and approaches and separates from the first substrate 2. For this reason, when no voltage is applied between the drive electrodes 14 and 16, the movable part 6 is held at a position close to the substrate 2 by a support beam 7 described later. They are separated by a gap S of about μm.

  The movable portion 6 may be provided with a plurality of through holes penetrating in the thickness direction in order to reduce resistance due to surrounding gas.

  For example, four support beams 7 are provided between the movable part 6 and the support part 5 so as to support the movable part 6 so as to be movable in the vertical direction. These support beams 7 are formed as, for example, beams bent in a crank shape, are positioned between the substrates 2 and 3, extend in the horizontal direction, and are spaced apart from the substrates 2 and 3 in the vertical direction.

  Each support beam 7 has a base end connected to the beam connecting portion 5 </ b> A of the support portion 5 and a distal end connected to the four corners of the movable portion 6. As shown in FIG. 5, the support beam 7 is bent and deformed in the vertical direction when the movable portion 6 is displaced toward the substrate 3.

  Further, the support beam 7 has a smaller thickness dimension (for example, about 30 to 70 μm) than the support portion 5 and the movable portion 6. As a result, the support beam 7 can be easily deformed in the vertical direction.

  For example, the inclined portion 8 is disposed between the support portion 5 and the support beam 7 and between the movable portion 6 and the support beam 7 in the silicon substrate 4. It is formed in a tapered shape whose thickness dimension is gradually reduced. An inclined surface along the (111) plane of the silicon crystal is formed on the surface of the inclined portion 8.

  The inclined portion 8 is limited to the case where the support portion 5, the movable portion 6, and the support beam 7 are provided separately, for example, between the support portion 5 and the support beam 7 or between the movable portion 6 and the support beam 7. Instead, for example, the support portion 5 and the movable portion 6 may be formed by being inclined, or the support beam 7 may be formed by being inclined.

  The first and second movable-side metal electrodes 9 and 10 are respectively formed on both surfaces of the silicon substrate 4 in the thickness direction. Here, on both surfaces of the silicon substrate 4 in the thickness direction, first and second insulating films 11 and 12 such as a silicon oxide film are provided over the entire surface. Therefore, the first and second insulating films 11 and 12 are disposed between the first and second movable-side metal electrodes 9 and 10 and the silicon substrate 4. The first and second insulating films 11 and 12 are not limited to the silicon oxide film, and may be formed of, for example, a silicon nitride film.

  Further, the first movable metal electrode 9 is formed over the entire back surface of the silicon substrate 4 and faces the first substrate 2. Thereby, the first movable side metal electrode 9 is formed on the back side of the support portion 5, the movable portion 6, the support beam 7, and the inclined portion 8, and the whole is electrically connected without disconnection in the middle. ing.

  On the other hand, the second movable metal electrode 10 is formed over the entire surface of the silicon substrate 4 and faces the second substrate 3. Thereby, the 2nd movable side metal electrode 10 is formed in the surface side of the support part 5, the movable part 6, the support beam 7, and the inclination part 8, and the whole is electrically connected. The first and second movable-side metal electrodes 9 and 10 are formed of a conductive metal thin film such as an alloy containing gold or gold, for example. The first and second movable metal electrodes 9 and 10 do not necessarily need to use the same material, and may be formed using different materials.

  A high frequency signal propagates to the first movable side metal electrode 9 and a fixed side signal electrode 15 described later. At this time, a skin effect is generated in the first movable-side metal electrode 9 or the like according to the frequency of the high-frequency signal, and a current flows concentrated on the surface of the first movable-side metal electrode 9 or the like. For this reason, the thickness dimension of the first movable-side metal electrode 9 is set to a value larger than the thickness of the skin by the high-frequency signal in order to reduce the transmission loss of the high-frequency signal. If the value is larger than the thickness of the skin, the transmission loss of the high-frequency signal is substantially constant regardless of the thickness dimension of the first movable-side metal electrode 9. For this reason, the thickness dimension of the first movable-side metal electrode 9 is set to a value as small as possible (for example, about twice the thickness of the skin) within a range larger than the thickness of the skin by the high-frequency signal. .

  Further, the thickness dimension of the second movable side metal electrode 10 is set so as to cancel out the warp generated in the movable part 6 due to the difference in the linear expansion coefficient between the first movable side metal electrode 9 and the silicon substrate 4. That value is set. For this reason, the thickness dimension of the 2nd movable side metal electrode 10 is set to the substantially same value as the thickness dimension of the 1st movable side metal electrode 9, for example.

  Note that a drive signal having a frequency lower than that of the high frequency signal is applied to the second movable metal electrode 10. For this reason, the thickness dimension of the second movable-side metal electrode 10 does not need to take into account the thickness of the skin, and may be set to a value smaller than the thickness dimension of the first movable-side metal electrode 9, for example. Good.

  Further, the first and second insulating films 11 and 12 also cause warpage of the movable portion 6. However, the first and second insulating films 11 and 12 have a smaller difference in linear expansion coefficient between the silicon substrate 4 and the first and second movable-side metal electrodes 9 and 10. For this reason, the first and second movable-side metal electrodes 9 and 10 predominantly act on the warp of the movable portion 6. Further, as shown in an insulating film forming step described later, the first and second insulating films 11 and 12 are simultaneously formed by heating the silicon substrate 4. For this reason, the thickness dimension of the 1st, 2nd insulating films 11 and 12 is set to the substantially same value, for example. As a result, in the present embodiment, the silicon substrate 4 has the first movable-side metal electrode 9, the first insulating film 11 and the second movable-side metal in a substantially symmetric state with respect to the thickness direction. An electrode 10 and a second insulating film 12 are formed.

  The movable side signal electrode 13 is formed on the back side of the movable portion 6 of the first movable side metal electrode 9 and faces the fixed side signal electrode 15 described later. The movable-side signal electrode 13 is formed in a square shape like the movable portion 6 and is displaced together with the movable portion 6 in the vertical direction. For this reason, the movable side signal electrode 13 approaches and separates from the fixed side signal electrode 15 as the movable portion 6 is displaced.

  The movable drive electrode 14 is formed on the surface side of the movable portion 6 of the second movable metal electrode 10 and faces a fixed drive electrode 16 described later. The movable drive electrode 14 is formed in a square shape like the movable portion 6, and generates an electrostatic attractive force by applying a voltage between the movable drive electrode 14 and the fixed drive electrode 16. Due to the electrostatic attractive force, the movable drive electrode 14 is displaced in the vertical direction toward the second substrate 3 together with the movable portion 6.

  The fixed-side signal electrode 15 is provided on the surface side of the first substrate 2 at a position facing the movable portion 6. As shown in FIGS. 1 and 2, the fixed-side signal electrode 15 is formed of a conductive metal thin film such as an alloy containing gold or gold. The thickness dimension of the fixed-side signal electrode 15 is set to a value larger than the thickness of the skin by the high-frequency signal (for example, a value about twice the thickness of the skin), like the first movable-side metal electrode 9. Has been. The fixed-side signal electrode 15 faces the movable-side signal electrode 13 over almost the entire surface and is connected to a signal extraction electrode 22 described later.

  In this case, an air gap capacitor is formed between the movable signal electrode 13 and the fixed signal electrode 15. The capacitance of the capacitor, that is, the capacitance between the movable side signal electrode 13 and the fixed side signal electrode 15 is configured to change according to the distance between the electrodes 13 and 15.

  The fixed drive electrode 16 is provided on the back side of the second substrate 3 at a position facing the movable portion 6. The fixed drive electrode 16 is formed of a conductive metal thin film such as gold, for example, in the same manner as the fixed signal electrode 15. Here, a low frequency drive signal is applied to the fixed drive electrode 16. For this reason, the thickness dimension of the fixed drive electrode 16 does not need to consider the thickness of the skin, and is set to a value smaller than the thickness dimension of the second movable metal electrode 10, for example. The fixed drive electrode 16 is located in the recessed portion 3A of the substrate 3 and faces the movable drive electrode 14 over almost the entire surface. Furthermore, the fixed drive electrode 16 is connected to a wiring portion 16A extending toward the outside of the recessed portion 3A. The fixed drive electrode 16 is connected to a drive lead electrode 24 described later via a wiring portion 16A.

  The fixed drive electrode 16 is opposed to the movable drive electrode 14 with a distance in the vertical direction (Z-axis direction). Then, by applying a voltage (drive signal) between the drive electrodes 14 and 16, a vertical electrostatic force that attracts the movable portion 6 toward the substrate 3 is generated, and this electrostatic force causes the movable portion 6 to move. Is driven in a direction away from the substrate 2.

  That is, when no voltage is applied between the drive electrodes 14 and 16, the movable portion 6 is held at a position close to the substrate 2 by the support beam 7 and is separated from the fixed drive electrode 16 via the gap S. .

  On the other hand, when a voltage is applied between the drive electrodes 14 and 16, the movable drive electrode 14 is attracted to the fixed drive electrode 16 by an electrostatic force acting between them. As a result, as shown in FIG. 5, the movable part 6 is displaced in the vertical direction to a position where it comes into contact with a stopper 18 (described later) provided on the fixed drive electrode 16 and is held at a position away from the substrate 2.

  The variable capacitance element 1 changes the electrostatic capacitance between the signal electrodes 13 and 15 by changing the distance between the movable signal electrode 13 and the fixed signal electrode 15 according to the position of the movable portion 6. The value is selectively switched.

  A plurality of signal side stoppers 17 are provided between the signal electrodes 13 and 15 and provided on the fixed side signal electrode 15. These stoppers 17 are formed as insulating protrusions, for example, of silicon oxide, and protrude from the fixed-side signal electrode 15 toward the movable portion 6.

  On the other hand, a plurality of driving-side stoppers 18 are provided on the fixed-side driving electrode 16 so as to be positioned between the driving electrodes 14 and 16. Similar to the stopper 17, these stoppers 18 are formed as insulating protrusions such as silicon oxide, and protrude from the fixed drive electrode 16 toward the movable portion 6.

  When no voltage is applied between the drive electrodes 14 and 16, the stopper 17 contacts the movable side signal electrode 13, and the stopper 18 is separated from the movable side drive electrode 14. At this time, the stopper 17 maintains an interval of a predetermined dimension between the signal electrodes 13 and 15 so that the signal electrodes 13 and 15 do not contact each other.

  On the other hand, when a voltage is applied between the drive electrodes 14 and 16, the stopper 17 is separated from the movable side signal electrode 13, and the stopper 18 is in contact with the movable side drive electrode 14. At this time, the stopper 18 maintains an interval of a predetermined dimension between the drive electrodes 14 and 16 so that the drive electrodes 14 and 16 do not contact each other.

  The first fixed-side metal electrode 19 is provided on the surface side of the first substrate 2 and is formed in a substantially same frame shape as the support portion 5. As a result, the first fixed metal electrode 19 comes into contact with a portion of the first movable metal electrode 9 provided on the support portion 5.

  The second fixed metal electrode 20 is provided on the back side of the second substrate 3 and is formed in a frame shape substantially the same as the support portion 5. Thereby, the 2nd fixed side metal electrode 20 contacts the site | part provided in the support part 5 among the 2nd movable side metal electrodes 10. FIG.

  Here, the first and second fixed-side metal electrodes 19 and 20 are formed of a conductive metal thin film such as gold, for example, in the same manner as the first and second movable-side metal electrodes 9 and 10. It has a thickness dimension of about 3 μm. The first fixed metal electrode 19 is pressure bonded to the first movable metal electrode 9, and the second fixed metal electrode 20 is pressure bonded to the second movable metal electrode 10. As a result, the space between the first and second substrates 2 and 3 and the silicon substrate 4 is sealed, and an airtight sealed space is defined between the first and second substrates 2 and 3. It is.

  The signal extraction electrodes 21 and 22 are provided on the first substrate 2 and connected to the signal electrodes 13 and 15, respectively. Here, the signal extraction electrode 21 is disposed at a position corresponding to the support portion 5, and is electrically connected to the movable side signal electrode 13 (movable side metal electrode 9) through the first fixed side metal electrode 19. . On the other hand, the signal extraction electrode 22 is disposed at a position corresponding to the movable portion 6 and is electrically connected to the fixed-side signal electrode 15.

  The signal extraction electrodes 21 and 22 are formed with signal via holes (through holes) penetrating in the thickness direction in the substrate 2 by using, for example, laser processing or microblasting, and copper is formed in the through holes. It is formed by filling a conductive metal material such as (Cu). The electrostatic capacitance between the signal electrodes 13 and 15 is output to an external circuit or the like via the signal extraction electrodes 21 and 22.

  The drive lead electrodes 23 and 24 are provided on the second substrate 3 and connected to the drive electrodes 14 and 16, respectively. Here, the drive lead electrode 23 is disposed at a position corresponding to the support portion 5 and is electrically connected to the movable drive electrode 14 (movable metal electrode 10) through the second fixed metal electrode 20. . On the other hand, the drive lead electrode 24 is disposed at a position corresponding to the wiring portion 16A, and is electrically connected to the fixed drive electrode 16 through the wiring portion 16A.

  These drive lead electrodes 23 and 24 are formed by filling a drive via hole with a conductive metal material, like the signal lead electrodes 21 and 22. The drive lead electrodes 23 and 24 connect the drive electrodes 14 and 16 to a DC power source 25 as shown in FIG. Thereby, the power source 25 applies a DC voltage of, for example, about 10 to 20 V between the drive electrodes 14 and 16 to generate an electrostatic attractive force between the drive electrodes 14 and 16.

  Next, a method for manufacturing the variable capacitance element 1 will be described with reference to FIGS.

  First, an unprocessed silicon substrate 30 (plane orientation (100)) made of single crystal silicon is prepared. In the anisotropic etching step shown in FIG. 6, the silicon substrate 30 is masked with the thermal oxide film (silicon oxide film) at positions corresponding to the support portion 5 and the movable portion 6 in the silicon substrate 30. Anisotropic etching is performed from the surface side.

  Thereby, a concave portion 31 that is recessed from the surface is formed at a position corresponding to between the support portion 5 and the movable portion 6 in the silicon substrate 30. A thick portion 30A having a large thickness of about 200 to 300 μm, for example, is formed at a position corresponding to the support portion 5 and the movable portion 6 in the silicon substrate 30, and between the support portion 5 and the movable portion 6. A thin portion 30B having a small thickness of about 50 μm, for example, is formed at a position corresponding to.

  The recess 31 is formed with an inclined surface along the (111) plane of the silicon crystal. For this reason, between the thick part 30A and the thin part 30B, an inclined part 30C whose thickness dimension is gradually reduced from the thick part 30A toward the thin part 30B is formed.

  Next, in the insulating film forming step shown in FIG. 7, for example, by heating the silicon substrate 30, silicon oxide films 32 and 33 to be the insulating films 11 and 12 are formed on both surfaces of the silicon substrate 30, respectively. The silicon oxide films 32 and 33 are not limited to being formed at the same time, and may be formed separately.

  Next, in the movable portion forming step shown in FIG. 8, unnecessary portions of the thin portion 30B of the silicon substrate 30 are removed using means such as RIE processing (reactive ion etching), and variable depending on the remaining portions. The support part 5, the movable part 6, and the support beam 7 of the capacitive element 1 are formed. At this time, an inclined portion 8 is formed between the support portion 5, the movable portion 6 and the support beam 7 by the inclined portion 30 </ b> C. Thereby, the silicon substrate 4 provided with the support portion 5, the movable portion 6, the support beam 7 and the inclined portion 8 is formed, and the insulating films 11 and 12 are formed on both surfaces of the silicon substrate 4.

  Next, in the movable metal electrode forming step shown in FIG. 9, conductive metal thin films such as gold (Au) are formed on both surfaces of the silicon substrate 4 by using, for example, vapor deposition. Here, when vapor deposition is performed, the space between the conductive material such as gold and the silicon substrate 4 is sufficiently separated. Thereby, although the conductive material is deposited on the front surface and the back surface of the silicon substrate 4, it does not adhere to the end surface (side surface) of the support beam 7. Thereby, the first and second movable-side metal electrodes 9 and 10 are formed over the entire surface of the both sides of the silicon substrate 4, and the gap between the first and second movable-side metal electrodes 9 and 10 is formed. Insulated state.

  Further, the support portion 5, the movable portion 6 and the support beam 7 are connected by an inclined portion 8. Therefore, for example, even when the first and second movable-side metal electrodes 9 and 10 are formed of a thin metal thin film having a film thickness of about several μm, the support portion 5, the movable portion 6 and the support beam 7 having different thickness dimensions are used. No disconnection occurs between the first and second movable-side metal electrodes 9 and 10. For this reason, between the part provided in the support part 5 among the movable side metal electrodes 9, and the movable side signal electrode 13 can be connected reliably. Similarly, the part provided in the support part 5 among the movable side metal electrodes 10 and the movable side drive electrode 14 can be reliably connected.

  On the other hand, in the first substrate forming step shown in FIG. 10, an insulating glass substrate 34 that becomes the first substrate 2 of the variable capacitance element 1 is prepared. And after forming a through hole in the glass substrate 34 using laser processing, a microblast method, etc., it fills with conductive metal materials, such as copper, in this through hole, for example by a plating process. Thereafter, the conductive metal material protruding from the through hole is polished to smooth the front and back surfaces of the glass substrate 34. As a result, signal extraction electrodes 21 and 22 connected to the electrodes 19 and 15, respectively, are formed on the glass substrate 34.

  Further, a conductive metal thin film such as gold is formed on the glass substrate 34 by using, for example, sputtering or vapor deposition. As a result, the fixed-side signal electrode 15 is formed on the surface of the glass substrate 34 at a position corresponding to the movable portion 6, and the first fixed-side metal electrode 19 is formed at a position corresponding to the support portion 5.

  Further, a silicon oxide film is formed on the surface of the fixed-side signal electrode 15 and patterned into a predetermined shape by etching or the like. Thus, a plurality of stoppers 17 protruding upward are formed on the fixed-side signal electrode 15. Through the above steps, the first substrate 2 including the fixed signal electrode 15 and the first fixed metal electrode 19 is formed.

  The through holes of the signal extraction electrodes 21 and 22 are formed by using laser processing, a microblast method, or the like. However, the present invention is not limited to this. For example, the glass substrate 34 may be formed using a photosensitive glass material, and through holes may be formed by irradiating the photosensitive glass material with ultraviolet rays or the like.

  Next, in the first substrate bonding step shown in FIG. 11, the fixed metal electrode 19 of the first substrate 2 and the first movable metal electrode 9 of the silicon substrate 4 are thermocompression bonded. Specifically, while the metal electrodes 9 and 19 are heated at a predetermined temperature in a range of, for example, 200 ° C. to 400 ° C., the predetermined value is set so that the movable side metal electrode 9 and the fixed side metal electrode 19 are in close contact with each other. A load (for example, a load of about 4 t on a 4-inch wafer) is applied. As a result, the metal electrodes 9 and 19 are bonded to each other by pressure, and the silicon substrate 4 is bonded and fixed to the first substrate 2. As a result, the movable portion 6 of the silicon substrate 4 is disposed at a position covering the fixed-side signal electrode 15 of the substrate 2, and the stopper 17 is sandwiched between the signal electrodes 13 and 15.

  On the other hand, in the second substrate forming step shown in FIG. 12, an insulating glass substrate 35 to be the second substrate 3 of the variable capacitance element 1 is prepared. Then, after a through hole penetrating in the thickness direction is formed in the glass substrate 35, a conductive metal material such as copper is filled in the through hole. Thereafter, the conductive metal material protruding from the through hole is polished to smooth the front and back surfaces of the glass substrate 35. As a result, driving lead electrodes 23 and 24 connected to the electrodes 20 and 16, respectively, are formed on the glass substrate 35.

  Next, the recessed portion 3A is formed by etching a predetermined portion of the back surface of the glass substrate 35. Then, a conductive metal thin film such as gold is formed on the glass substrate 35 by using, for example, sputtering or vapor deposition. As a result, on the back surface of the glass substrate 35, the fixed drive electrode 16 is formed in the recessed portion 3 </ b> A, and the second fixed metal electrode 20 is formed at a position corresponding to the support portion 5.

  Further, a silicon oxide film is formed on the surface of the fixed-side signal electrode 15, and this is patterned into a predetermined shape by etching or the like. Thus, a plurality of stoppers 18 projecting downward are formed on the fixed-side signal electrode 15. Through the above steps, the second substrate 3 including the fixed-side signal electrode 15 and the second fixed-side metal electrode 20 is formed.

  Next, in the second substrate bonding step shown in FIG. 13, substantially the same as the first substrate bonding step, the fixed metal electrode 20 of the second substrate 3 and the second movable metal electrode 10 of the silicon substrate 4. And thermocompression bonding. Thereby, the metal electrodes 10 and 20 are pressure-bonded to each other, and the second substrate 3 is bonded and fixed to the surface side of the silicon substrate 4. As a result, the movable portion 6 of the silicon substrate 4 is disposed at a position facing the fixed drive electrode 16 of the substrate 3, and the variable capacitance element 1 is completed.

  The variable capacitance element 1 according to the present embodiment is manufactured by the above-described manufacturing method, and the operation thereof will be described next.

  First, in a state where no voltage is applied to the variable capacitance element 1, as shown in FIG. 1, the movable portion 6 (movable side signal electrode 13) is held at a position close to the fixed side signal electrode 15, and the signal electrode 13 , 15 has a capacitance value corresponding to the distance between the signal electrodes 13, 15 close to each other.

  As shown in FIG. 5, when a voltage is applied between the drive electrodes 14 and 16, an electrostatic force is generated between them. As a result, the movable portion 6 is displaced in the vertical direction to a position where it abuts on the fixed drive electrode 16 (stopper 18) while bending and deforming the support beam 7, and the movable signal electrode 13 is separated from the fixed signal electrode 15. Held in the position. As a result, the capacitance between the signal electrodes 13 and 15 becomes a capacitance value corresponding to the distance between the signal electrodes 13 and 15 that are separated from each other. Therefore, the capacitance is switched according to the presence or absence of voltage application. It is possible to switch connection and disconnection between the signal electrodes 13 and 15 with respect to the signal.

  Thus, according to the present embodiment, since the first and second movable-side metal electrodes 9 and 10 are formed over the entire surface on both surfaces of the silicon substrate 4 in the thickness direction, the first movable side is formed. The movable side signal electrode 13 that is close to and away from the fixed side signal electrode 15 can be formed by using a portion of the metal electrode 9 that is disposed in the movable portion 6, and the second movable side metal electrode 10 Of these, the movable drive electrode 14 for applying an electrostatic attractive force between the movable drive electrode 6 and the fixed drive electrode 16 can be formed by using the portion disposed in the movable portion 6. For this reason, since the movable part 6 can be displaced in the thickness direction by applying a voltage between the fixed side drive electrode 16 and the movable side drive electrode 14, the fixed side according to the displacement of the movable part 6. The variable capacitance element 1 in which the electrostatic capacitance between the signal electrode 15 and the movable signal electrode 13 changes can be configured.

  Further, since the movable side signal electrode 13 and the movable side drive electrode 14 are formed using the first and second movable side metal electrodes 9 and 10, the first and second movable side metal electrodes 9 and 10 are bonded by pressure bonding. The movable signal electrode 13 and the movable drive electrode 14 can be electrically connected to an external processing circuit or the like through the first and second fixed metal electrodes 19 and 20. For this reason, since it is possible to transmit a detection signal and apply a drive signal to / from the outside without passing through silicon, it is possible to suppress signal attenuation, and a signal conductor that transmits the signal electrodes 13 and 15. Loss can be reduced and the response speed of the movable part 6 can be improved.

  Further, since the first and second substrates 2 and 3 are formed with the first and second fixed-side metal electrodes 19 and 20 that are in contact with the first and second movable-side metal electrodes 9 and 10, the first and second substrates 2 and 3 are formed. , The second movable-side metal electrodes 9 and 10 and the first and second fixed-side metal electrodes 19 and 20 are joined by pressure bonding, so that the silicon substrate 4 is interposed between the first and second substrates 2 and 3. Can be fixed. Therefore, the fixed metal electrodes 19 and 20 are joined by pressure bonding using a part of the first movable metal electrode 9 that becomes the movable signal electrode 13 and the second movable metal electrode 10 that becomes the movable drive electrode 14. can do. Therefore, it is not necessary to pattern the first and second movable metal electrodes 9 and 10, and only the first and second movable metal electrodes 9 and 10 are formed on both surfaces of the silicon substrate 4. Therefore, as compared with the case where a metal thin film for bonding is separately provided on the silicon substrate 4, the manufacturing process can be simplified and the productivity can be increased.

  In addition, the first and second movable-side metal electrodes 9 and 10 and the first and second fixed-side metal electrodes 19 and 20 are bonded to each other between the first and second substrates 2 and 3 by pressure bonding. A sealed space for accommodating the movable portion 6 can be defined. At this time, since the sealed space can be sealed in an airtight state, the air resistance of the movable portion 6 can be reduced and its responsiveness can be increased by performing pressure bonding in a reduced pressure atmosphere. .

  Since the first and second insulating films 11 and 12 are provided between the silicon substrate 4 and the first and second movable-side metal electrodes 9 and 10, the first and second insulating films are provided. 11 and 12 can be used to insulate the first and second movable metal electrodes 9 and 10 from each other. For this reason, since the first and second movable metal electrodes 9 and 10 can have separate functions, the first movable metal electrode 9 can form the movable signal electrode 13 used for capacitance detection and the like. The movable side drive electrode 14 for applying an electrostatic force to the movable part 6 can be formed by the second movable side metal electrode 10.

  Also, since the insulating films 11 and 12 can insulate between the silicon substrate 4 and the first and second movable-side metal electrodes 9 and 10, the resistance between the silicon substrate 4 and the metal electrodes 9 and 10 having high resistance can be reduced. Contact points can be eliminated, and signal loss can be reduced.

  Further, since the silicon substrate 4 has the support beam 7 formed with a smaller thickness than the thickness of the support portion 5 and the movable portion 6, the spring constant of the support beam 7 is reduced to facilitate the movable portion 6. Can be displaced. Further, the silicon substrate 4 includes an inclined portion 8 whose thickness dimension is gradually reduced from the support portion 5 toward the support beam 7, and an inclined portion 8 whose thickness dimension is gradually reduced from the movable portion 6 toward the support beam 7. Therefore, no step is formed between the support portion 5 and the support beam 7 or between the movable portion 6 and the support beam 7. That is, the front surface and the back surface of the silicon substrate 4 are smoothly continuous.

  On the other hand, when the first and second movable-side metal electrodes 9 and 10 are formed on both surfaces of the silicon substrate 4 by using, for example, a vapor deposition method or a sputtering method, a conductive metal material that is a film forming material and a film formation target By sufficiently separating the silicon substrate 4, the conductive metal material adheres to the both surfaces of the silicon substrate 4 from the vertical direction. For this reason, by using a vapor deposition method or the like, the first and second movable-side metal electrodes 9 and 10 can be formed in a state where the support portion 5 and the movable portion 6 and the support beam 7 are continuous. This ensures that the first and second movable metal electrodes 9 and 10 are formed on the entire surface of the silicon substrate 4 without disconnection in the middle of the first and second movable metal electrodes 9 and 10. can do.

  Further, when the first and second movable-side metal electrodes 9 and 10 are formed by vapor deposition or the like, the end surface of the silicon substrate 4 such as the side surface of the support beam 7 or the inner wall surface of the support portion 5 having a frame shape. Since no metal thin film is formed on the movable metal electrodes 9, it is possible to prevent the movable side metal electrodes 9, 10 from being short-circuited.

  Furthermore, since a stopper 18 made of an insulating material is provided between the fixed drive electrode 16 and the movable drive electrode 14, the stopper 18 prevents contact between the fixed drive electrode 16 and the movable drive electrode 14. Can be prevented from being electrically short-circuited.

  Moreover, the thickness dimension of the 1st movable side metal electrode 9 and the stationary side signal electrode 15 was set to the larger value than the thickness of the skin of the high frequency signal to propagate. Therefore, the first movable-side metal electrode 9 and the fixed-side signal electrode 15 can be formed thin and the height dimension of the variable capacitance element 1 can be reduced within a range where transmission loss of high-frequency signals does not increase. .

  Furthermore, the thickness dimension of the second movable-side metal electrode 10 is set so as to cancel out the warp generated in the movable portion 6 due to the difference in the linear expansion coefficient between the first movable-side metal electrode 9 and the silicon substrate 4. That value was set. Thereby, even when the temperature change occurs in the variable capacitance element 1, it is possible to suppress the warp of the movable portion 6 and the like accompanying the temperature change. As a result, for example, the maximum value, the minimum value, the change width, etc. of the capacitance between the movable side signal electrode 13 and the fixed side signal electrode 15 are suppressed from fluctuations in temperature. Can be increased.

  Next, FIG. 14 and FIG. 15 show a second embodiment according to the present invention. The feature of this embodiment is that two fixed-side signal electrodes are provided on a first substrate, and a high-frequency signal is sent between them. This is applied to a switching element that switches. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The switch element 41 as the MEMS switch element includes the first and second substrates 2 and 3, the silicon substrate 4, the support portion 5, the movable portion 6, the support beam 7, and the inclined portion, as in the first embodiment. 8. First and second movable metal electrodes 9, 10, movable signal electrode 13, movable drive electrode 14, fixed signal electrode 42, fixed drive electrode 16, and first and second fixed metal electrodes 19, 20 and so on.

  However, for example, two fixed-side signal electrodes 42 are provided on the substrate 2 at a position facing the movable portion 6 to form, for example, a microstrip line that transmits a high-frequency signal. Then, one end side of each fixed-side signal electrode 42 is opposed to each other with an interval in the X-axis direction at a position corresponding to approximately the center of the movable-side signal electrode 13. The other end of the fixed-side signal electrode 42 extends to a position outside the movable portion 6, and this part is connected to a signal extraction electrode 43 formed of a signal via hole formed in the first substrate 2. On the other hand, the movable signal electrode 13 is not connected to the signal extraction electrode, unlike the first embodiment.

  Then, the switch element 41 moves the movable side signal electrode 13 close to and away from the fixed side signal electrode 42 according to the presence or absence of voltage application, so that a high frequency signal is generated between the left and right fixed side signal electrodes 42. It is configured to transmit and block.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment.

  In the second embodiment, the fixed-side signal electrode 42 forms a microstrip line. However, for example, another transmission line that transmits a high-frequency signal such as a coplanar line may be formed. .

  Next, FIG. 16 shows a third embodiment according to the present invention, which is characterized in that it is applied to a metal-metal contact type relay element. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As in the first embodiment, the relay element 51 as the MEMS switch element includes first and second substrates 2 and 3, a silicon substrate 4, a support portion 5, a movable portion 6, a support beam 7, and an inclined portion. 8, first and second movable-side metal electrodes 9, 10, movable-side signal electrode 13, movable-side drive electrode 14, fixed-side signal electrode 15, fixed-side drive electrode 16, and first and second fixed-side metal electrodes 19, 20 and so on.

  Here, in place of the stopper 17 of the first embodiment, a plurality of protruding contact portions 52 formed of a conductive material protrude from the surface of the fixed-side signal electrode 15.

  These contact portions 52 are held in contact with the movable-side signal electrode 13 when no voltage is applied to the relay element 51, and connect the fixed-side signal electrode 15 and the movable-side signal electrode 13. . Further, when a voltage is applied between the drive electrodes 14 and 16 of the relay element 51, the movable-side signal electrode 13 is displaced in a direction away from each contact portion 52, and the signal electrodes 13 and 15 are insulated from each other. Become.

  As described above, the relay element 51 of the metal-metal contact type is configured such that each contact portion 52 is brought into contact with the movable side signal electrode 13 or separated from the movable side signal electrode 13 according to the presence or absence of voltage application. 13 and 15 are connected and disconnected.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operation and effect as in the first embodiment, and the applicable range is also applied to the metal-metal contact type relay element 51 as the MEMS switch element. Can be spread.

  Next, FIGS. 17 to 26 show a fourth embodiment. The feature of this embodiment is that the movable portion is more than the support portion in a state before the support portion is fixed to the first substrate. It is that it formed in the shape which protruded toward 1 board | substrate.

  In the figure, the switch element 61 includes first and second substrates 62 and 63, a silicon substrate 64, a support portion 65, a movable portion 66, a support beam 67, an inclined portion 68, substantially the same as in the first embodiment. First and second movable-side metal electrodes 69 and 70, movable-side signal electrode 73, movable-side drive electrode 74, fixed-side signal electrode 75, fixed-side drive electrode 76, and first and second fixed-side metal electrodes 79, 81 and the like.

  The first and second substrates 62 and 63 are made of, for example, an insulating glass material, and are formed in a square shape having a size of about several millimeters. The substrates 62 and 63 and the silicon substrate 64 extend in the horizontal direction along the X axis and the Y axis, similarly to the substrates 2 and 3 and the silicon substrate 4 according to the first embodiment.

  In addition, a recessed portion 63 </ b> A that is recessed in a substantially rectangular shape is formed on the back surface side of the second substrate 63. As a result, a sealed space for accommodating a movable portion 66 described later is defined between the substrates 62 and 63 at a position corresponding to the recessed portion 63A.

  On the other hand, the silicon substrate 64 is formed using, for example, single crystal silicon having a resistivity of 5 kΩ · cm or more, and both sides in the thickness direction are sandwiched between the first and second substrates 62 and 63. A support portion 65, a movable portion 66, and a support beam 67, which will be described later, are formed on the silicon substrate 64 using a micromachining technique.

  The support portion 65 is formed on the silicon substrate 64 and is fixed to the first and second substrates 62 and 63. The support portion 65 is formed in a rectangular frame shape extending along the peripheral edges of the substrates 62 and 63, for example, and surrounds the movable portion 66, the support beam 67, and the like. Here, two beam connecting portions 65 </ b> A located on both sides in the X-axis direction with the movable portion 66 interposed therebetween are provided inside the support portion 65. The support portion 65 has a thickness dimension of about 200 to 300 μm, for example, and holds a sealed space in which the movable portion 66 is disposed between the substrates 62 and 63.

  The movable portion 66 is formed on the silicon substrate 64 and is supported by the support portion 65 using a support beam 67 described later. The movable portion 66 is disposed at a position facing the recessed portion 63A of the substrate 63, and is movable in the thickness direction (Z-axis direction). Here, the movable portion 66 is formed in a rectangular flat plate shape, and has a thickness dimension (for example, about 200 to 300 μm) that is the same as that of the support portion 65. In addition, the movable portion 66 is formed together with the support portion 65, the support beam 67, and the like by performing an etching process on the silicon substrate 64.

  The movable portion 66 is displaced in the vertical direction (Z-axis direction) by an electrostatic force generated between drive electrodes 74 and 76, which will be described later, and approaches and separates from the first substrate 62. For this reason, the movable portion 66 is held at a position close to the substrate 62 by a support beam 67 described later when no voltage is applied between the drive electrodes 74 and 76. They are separated by a gap S of about μm.

  In addition, the movable portion 66 protrudes toward the first substrate 62 from the back surface of the support portion 65 and is recessed from the front surface of the support portion 65 before the support portion 65 is fixed to the first substrate 62. It is formed in a shape (see FIG. 24). For this reason, when the support part 65 is fixed to the first substrate 62, the movable part 66 is elastically pressed toward the first substrate 62 by the support beam 67.

  The movable portion 66 may be provided with a plurality of through holes penetrating in the thickness direction in order to reduce resistance due to surrounding gas.

  For example, four support beams 67 are provided between the movable portion 66 and the support portion 65 so as to support the movable portion 66 so as to be movable in the vertical direction. These support beams 67 are formed, for example, as beams bent in a crank shape, are positioned between the substrates 62 and 63, extend in the horizontal direction, and are spaced apart from the substrates 62 and 63 in the vertical direction.

  Further, each support beam 67 is connected to the beam connecting portion 65 </ b> A of the support portion 65 at the base end side and to the four corners of the movable portion 66 at the distal end side. The support beam 67 is bent and deformed in the vertical direction when the movable portion 66 is displaced toward the substrate 63, like the support beam 7 according to the first embodiment.

  Furthermore, the support beam 67 has a thickness dimension (for example, about 10 to 70 μm) smaller than the support portion 65 and the movable portion 66. As a result, the support beam 67 can be easily deformed in the vertical direction.

  Further, the support beam 67 is formed in a shape having a thickness dimension smaller than that of the support portion 65 and the movable portion 66 by performing isotropic etching from the back side of the silicon substrate 64, for example (see FIG. 24). For this reason, a step portion 67A is formed between the support beam 67, the support portion 65, and the movable portion 66.

  The inclined portion 68 is disposed, for example, in the beam connecting portion 65A of the support portion 65 in the silicon substrate 64, and is formed in a tapered shape whose thickness dimension is gradually reduced from the support portion 65 toward the support beam 67. An inclined surface along the (111) plane of the silicon crystal is formed on the surface of the inclined portion 68.

  In addition, although the inclined part 68 was formed when a part of the support part 65 inclined, it may be formed between the support part 65 and the support beam 67, for example, and a part of the support beam 67 is inclined. May be formed.

  The first and second movable-side metal electrodes 69 and 70 are respectively formed on both surfaces of the silicon substrate 64 in the thickness direction. Here, on both surfaces of the silicon substrate 64 in the thickness direction, first and second insulating films 71 and 72 such as a silicon oxide film are provided over the entire surface. Therefore, first and second insulating films 71 and 72 are disposed between the first and second movable-side metal electrodes 69 and 70 and the silicon substrate 64.

  The first and second insulating films 71 and 72 are formed together after the movable portion 66 and the like are formed on the silicon substrate 64. For this reason, in the present embodiment, the first and second insulating films 71 and 72 are connected to each other through end face portions such as the support portion 65, the movable portion 66, and the support beam 67. However, the present invention is not limited to this, and the first and second insulating films 71 and 72 are separated from each other in the same manner as the first and second insulating films 11 and 12 according to the first embodiment. Also good. Further, the first and second insulating films 71 and 72 are not limited to the silicon oxide film, and may be formed of, for example, a silicon nitride film.

  The first movable metal electrode 69 is formed, for example, over the entire back surface of the silicon substrate 64 and faces the first substrate 62. However, since the stepped portion 67A is formed between the support beam 67 and the support portion 65 and the movable portion 66, the support portion 65, the movable portion 66, and the support beam 67 of the first movable side metal electrode 69 are formed. The parts corresponding to are electrically disconnected from each other.

  On the other hand, the second movable metal electrode 70 is formed on the surface side of the silicon substrate 64 and faces the second substrate 63. Here, a portion of the second movable-side metal electrode 70 provided on one beam connecting portion 65A serves as a wiring support portion 70A and is insulated from the other portions. The wiring support portion 70A is disposed at a position facing a wiring portion 76A described later.

  Further, the remaining portion of the second movable-side metal electrode 70 excluding the wiring support portion 70A is formed on the surface side of the support portion 65, the movable portion 66, the support beam 67, and the inclined portion 68. For this reason, the remaining part of the second movable-side metal electrode 70 is continuously formed through the other beam connecting part 65A, and the whole is electrically connected without disconnection in the middle.

  The first and second movable-side metal electrodes 69 and 70 are formed of a conductive metal thin film such as an alloy containing gold or gold, for example. The first and second movable-side metal electrodes 69 and 70 do not necessarily need to use the same material, and may be formed using different materials.

  Further, the high frequency signal propagates to the movable side signal electrode 73 formed on the movable portion 66 of the first movable side metal electrode 69. Further, the high-frequency signal propagates to the fixed-side signal electrode 75 described later. At this time, a skin effect is generated in the first movable metal electrode 69 and the like according to the frequency of the high frequency signal, and a current flows concentrated on the surface of the first movable metal electrode 69 and the like. For this reason, the thickness dimension of the first movable-side metal electrode 69 is set to a value larger than the thickness of the skin by the high-frequency signal in order to reduce the transmission loss of the high-frequency signal. If the value is larger than the thickness of the skin, the transmission loss of the high-frequency signal is substantially constant regardless of the thickness dimension of the first movable-side metal electrode 69. For this reason, the thickness dimension of the first movable-side metal electrode 69 is set to a value as small as possible (for example, about twice the thickness of the skin) within a range larger than the thickness of the skin by the high-frequency signal. .

  Further, the thickness dimension of the second movable side metal electrode 70 is set so as to cancel out the warp generated in the movable part 66 due to the difference in the linear expansion coefficient between the first movable side metal electrode 69 and the silicon substrate 64. That value is set. For this reason, the thickness dimension of the 2nd movable side metal electrode 70 is set to the substantially same value as the thickness dimension of the 1st movable side metal electrode 69, for example. Further, the thickness dimensions of the first and second insulating films 71 and 72 are set to substantially the same value, for example. Thereby, in the present embodiment, the first movable-side metal electrode 69, the first insulating film 71, and the second movable-side metal are formed on the silicon substrate 64 in a substantially symmetric state with respect to the thickness direction. An electrode 70 and a second insulating film 72 are formed.

  A driving signal having a frequency lower than that of the high frequency signal is applied to the fixed side driving electrode 76 described later. For this reason, the thickness dimension of the fixed drive electrode 76 does not need to consider the thickness of the skin, and may be set to a value smaller than the thickness dimension of the first movable metal electrode 69, for example.

  The movable-side signal electrode 73 is formed on the back side of the movable portion 66 of the first movable-side metal electrode 69 and faces a fixed-side signal electrode 75 described later. The movable-side signal electrode 73 is formed in a quadrangular shape like the movable portion 66 and is displaced together with the movable portion 66 in the vertical direction. For this reason, the movable-side signal electrode 73 approaches and separates from the fixed-side signal electrode 75 as the movable portion 66 is displaced.

  The movable drive electrode 74 is formed on the surface side of the movable portion 66 of the second movable metal electrode 70 and faces a fixed drive electrode 76 described later. The movable drive electrode 74 is formed in a square shape like the movable portion 66, and generates an electrostatic attractive force by applying a voltage between the movable drive electrode 74 and the fixed drive electrode 76. Due to the electrostatic attractive force, the movable drive electrode 74 is displaced in the vertical direction toward the second substrate 63 together with the movable portion 66.

  For example, two fixed-side signal electrodes 75 are provided on the substrate 62 at a position facing the movable portion 66 to form, for example, a microstrip line that transmits a high-frequency signal. Then, one end side of each fixed-side signal electrode 75 is opposed to each other with an interval in the X-axis direction at a position corresponding to substantially the center of the movable-side signal electrode 73. The other end of each fixed-side signal electrode 75 extends to a position outside the movable portion 66, and this portion is connected to a later-described signal extraction electrode 82 formed of a signal via hole formed in the first substrate 62. ing. On the other hand, unlike the first embodiment, the movable signal electrode 73 is not connected to the signal extraction electrode.

  The fixed-side signal electrode 75 is formed of a conductive metal thin film such as copper. In addition, the thickness dimension of the fixed-side signal electrode 75 is set to a value (for example, a value about twice the thickness of the skin) larger than the thickness of the skin due to the high-frequency signal, like the first movable-side metal electrode 69. Has been.

  Then, the switch element 61 moves the movable signal electrode 73 close to and away from the fixed signal electrode 75 according to the presence or absence of voltage application, thereby generating a high frequency signal between the left and right fixed signal electrodes 75. It is configured to transmit and block.

  The fixed drive electrode 76 is provided on the back surface side of the second substrate 63 at a position facing the movable portion 66. The fixed drive electrode 76 is formed of a conductive metal thin film such as gold, for example, in substantially the same manner as the fixed drive electrode 16 according to the first embodiment. The fixed drive electrode 76 is positioned in the recessed portion 63A of the substrate 63 and faces the movable drive electrode 74 over almost the entire surface. Furthermore, the fixed drive electrode 76 is connected to a wiring portion 76A extending toward the outside of the recessed portion 63A. The fixed drive electrode 76 is connected to a drive lead electrode 84 described later via a wiring portion 76A.

  The fixed drive electrode 76 is opposed to the movable drive electrode 74 with an interval in the vertical direction (Z-axis direction). Then, by applying a voltage (drive signal) between the drive electrodes 74 and 76, a vertical electrostatic force that attracts the movable portion 66 toward the substrate 63 is generated, and the movable portion 66 is generated by this electrostatic force. Is driven in a direction away from the substrate 62.

  That is, when no voltage is applied between the drive electrodes 74 and 76, the movable portion 66 is held at a position close to the substrate 62 by the support beam 67 and is separated from the fixed drive electrode 76 via the gap S. .

  On the other hand, when a voltage is applied between the drive electrodes 74 and 76, the movable side drive electrode 74 is attracted to the fixed side drive electrode 76 due to an electrostatic force acting between them. As a result, the movable portion 66 is displaced in the vertical direction to a position where it comes into contact with a later-described stopper 78 provided on the fixed drive electrode 76 and is held at a position separated from the substrate 62.

  A plurality of signal-side stoppers 77 are provided between the signal electrodes 73 and 75 and provided on the fixed-side signal electrode 75. These stoppers 77 are formed as insulating protrusions, for example, of silicon oxide or the like, and protrude from the fixed-side signal electrode 75 toward the movable portion 66.

  On the other hand, the drive-side stopper 78 is formed by, for example, a plurality of protrusions (only one is shown) provided in the recessed portion 63A. For this reason, the stopper 78 is formed of an insulating glass material or the like, like the second substrate 63. The distal end portion of the stopper 78 is located between the drive electrodes 74 and 76. Note that the stopper 78 may be formed by an insulating protrusion provided on the fixed drive electrode 76 as in the stopper 18 according to the first embodiment.

  When no voltage is applied between the drive electrodes 74 and 76, the stopper 77 comes into contact with the movable signal electrode 73 and the stopper 78 is separated from the movable drive electrode 74. At this time, the stopper 77 maintains a predetermined distance between the signal electrodes 73 and 75 so that the signal electrodes 73 and 75 do not come into contact with each other.

  On the other hand, when a voltage is applied between the drive electrodes 74 and 76, the stopper 77 is separated from the movable side signal electrode 73, and the stopper 78 is in contact with the movable side drive electrode 74. At this time, the stopper 78 maintains an interval of a predetermined dimension between the drive electrodes 74 and 76 so that the drive electrodes 74 and 76 do not contact each other.

  The first fixed-side metal electrode 79 is provided on the surface side of the first substrate 62 and is formed in a frame shape that is substantially the same as the support portion 65. The first fixed-side metal electrode 79 opposes a portion of the first movable-side metal electrode 69 provided on the support portion 65. Here, the first fixed-side metal electrode 79 is formed of a conductive metal thin film such as copper, for example, like the first movable-side metal electrode 69, and has a thickness of about 1 to 3 μm, for example. Yes.

  A bonding electrode 80 is formed on the surface of the first fixed metal electrode 79. At this time, the joining electrode 80 is formed of a conductive metal thin film such as gold, for example, in substantially the same manner as the first movable metal electrode 69. The first fixed metal electrode 79 is pressure bonded to the first movable metal electrode 69 via the bonding electrode 80.

  In the present embodiment, the fixed-side signal electrode 75 and the fixed-side metal electrode 79 are formed using a conductive metal material such as copper. However, the present invention is not limited to this, and it may be formed using gold or an alloy containing gold, similarly to the fixed-side signal electrode 15 according to the first embodiment. In this case, the fixed-side metal electrode 79 and the movable-side metal electrode 69 can be directly bonded by pressure bonding.

  The second fixed-side metal electrode 81 is provided on the back side of the second substrate 63 in a state of being insulated from the fixed-side drive electrode 76, and is formed in a frame shape that is substantially the same as the support portion 65. As a result, the second fixed-side metal electrode 81 comes into contact with a portion of the second movable-side metal electrode 70 that is provided on the support portion 65.

  Here, the second fixed-side metal electrode 81 is formed of a conductive metal thin film such as gold, for example, in the same manner as the second movable-side metal electrode 70, and has a thickness of about 1 to 3 μm, for example. ing. The second fixed side metal electrode 81 is pressure bonded to the second movable side metal electrode 70. As a result, the space between the first and second substrates 62 and 63 and the silicon substrate 64 is sealed, and an airtight sealed space is defined between the first and second substrates 62 and 63. It is.

  Two signal extraction electrodes 82 are provided on the first substrate 62, and are connected to the two signal electrodes 75, respectively. Here, the signal extraction electrode 82 is disposed at a position corresponding to the movable portion 66 and is electrically connected to the fixed-side signal electrode 75. These signal lead-out electrodes 82 are formed with signal via holes (through holes) penetrating in the thickness direction in the substrate 62 by using, for example, laser processing or microblasting, and copper (Cu ) Or the like.

  The drive lead electrodes 83 and 84 are provided on the second substrate 63 and connected to the drive electrodes 74 and 76, respectively. Here, the drive lead electrode 83 is disposed at a position corresponding to the other beam connecting portion 65A, and is electrically connected to the movable drive electrode 74 (movable metal electrode 70) through the second fixed metal electrode 81. Has been. On the other hand, the drive lead electrode 84 is disposed at a position corresponding to the one beam connecting portion 65A, and is electrically connected to the fixed drive electrode 76 through the wiring portion 76A. Similar to the signal lead electrode 82, these drive lead electrodes 83 and 84 are formed by filling a drive via hole with a conductive metal material.

  Next, a method for manufacturing the switch element 61 will be described with reference to FIGS.

  First, an unprocessed silicon substrate 90 (plane orientation (100)) made of single crystal silicon is prepared. In the anisotropic etching step shown in FIG. 19, the position (peripheral portion) corresponding to the support portion 65 is masked on the surface side of the silicon substrate 90 by the thermal oxide film 91 (silicon oxide film). On the other hand, on the back surface side of the silicon substrate 90, a position corresponding to the movable portion 66 (center portion) is masked by the thermal oxide film 92. In this state, anisotropic etching is performed on the silicon substrate 90 from the front and back surfaces by wet etching using, for example, TMAH (tetramethylammonium hydroxide). The anisotropic etching is not limited to wet etching, and dry etching may be used.

  As a result, a recess 93 is formed in a portion of the silicon substrate 90 corresponding to the movable portion 66 and the support beam 67. At this time, the recessed portion 93 is recessed from the surface facing the second substrate 63 with a depth dimension d1 of several μm (for example, 1 to 5 μm), and has a protruding dimension d2 of several μm (for example, 1 to 5 μm). It protrudes to the back side facing the one substrate 62.

  Further, the depression 93 is formed with an inclined surface along the (111) plane of the silicon crystal. Therefore, an inclined portion 90 </ b> A that is inclined from the periphery of the recessed portion 93 toward the recessed portion 93 is formed on the front surface side of the silicon substrate 90. When the anisotropic etching is completed, the thermal oxide films 91 and 92 are removed as shown in FIG.

  The anisotropic etching may be performed simultaneously on both surfaces of the silicon substrate 90, or may be performed separately on the front surface and the back surface. When anisotropic etching is separately performed on the front surface and the back surface of the silicon substrate 90, the protrusion dimension d2 of the recess portion 93 can be adjusted independently of the depth dimension d1 of the recess portion 93. Thereby, the pressing force for pressing the movable portion 66 against the first substrate 62 and the driving stroke of the movable portion 66 can be adjusted independently.

  Next, in the thin-walled portion forming step shown in FIG. 21, for example, isotropic etching is performed on the portion of the silicon substrate 90 corresponding to the support beam 67 from the back surface side. As a result, a thick portion 94 having a large thickness of about 200 μm, for example, is formed at a position corresponding to the support portion 65 in the silicon substrate 90. A thin portion 95 having a small thickness of about 10 to 70 μm, for example, is formed at a position corresponding to the support beam 67 in the silicon substrate 90. Further, a protruding portion 96 protruding to the back surface side with a protruding dimension of, for example, about 150 μm is formed at a position corresponding to the movable portion 66 in the silicon substrate 90.

  When the etching process is completed, a back metal film 97 is formed on the back side of the silicon substrate 90 using a material having high thermal conductivity such as aluminum. The back metal film 97 is used to prevent the temperature distribution from occurring in the silicon substrate 90 when performing RIE processing, which will be described later, and to perform the etching process uniformly on the entire silicon substrate 90.

  Next, in the movable part forming step shown in FIG. 22, in consideration of ease of attaching a mask, for example, etching is performed through the silicon substrate 90 from the surface side of the silicon substrate 90 with few irregularities. Therefore, first, the back surface side of the silicon substrate 90 is attached to the etching support substrate 98 via the resist film 98A and the like. In this state, for example, RIE processing (reactive ion etching) is performed from the surface side of the silicon substrate 90. Thereby, unnecessary portions of the thin portion 95 of the silicon substrate 90 are removed, and the support portion 65, the movable portion 66, and the support beam 67 of the switch element 61 are formed by the remaining portions. At this time, an inclined portion 68 is formed in the beam connecting portion 65A of the support portion 65 by the inclined portion 90A. Thereby, the silicon substrate 64 including the support portion 65, the movable portion 66, the support beam 67, and the inclined portion 68 is formed. After the silicon substrate 64 is formed, the silicon substrate 64 is removed from the support substrate 98, and the resist film 98A and the back metal film 97 are removed.

  Next, in the insulating film forming step shown in FIG. 23, the insulating films 71 and 72 made of a silicon oxide film are formed on both surfaces of the silicon substrate 64 by heating the silicon substrate 64, for example. At this time, the insulating films 71 and 72 have a thickness dimension of about 1 μm, for example. Further, not only the front and back surfaces of the silicon substrate 64 but also the end surfaces are oxidized. For this reason, the insulating films 71 and 72 are connected to each other through the end surface portions of the support portion 65, the movable portion 66, and the support beam 67.

  Next, in the movable metal electrode forming step shown in FIG. 24, conductive metal thin films such as gold (Au) are formed on both surfaces of the silicon substrate 64 by using, for example, vapor deposition. Here, when vapor deposition is performed, the space between the conductive material such as gold and the silicon substrate 64 is sufficiently separated. As a result, the conductive material is deposited on the front and back surfaces of the silicon substrate 64, but does not adhere to the end surfaces (side surfaces) of the support beams 67. As a result, the first and second movable metal electrodes 69 and 70 are formed on both surfaces of the silicon substrate 64, and the first and second movable metal electrodes 69 and 70 are insulated from each other. It becomes.

  An inclined portion 68 is formed in the beam connecting portion 65 </ b> A of the support portion 65. For this reason, for example, even when the second movable-side metal electrode 70 is formed by a thin metal thin film having a thickness of about several μm, the second movable-side metal is formed between the support portion 65 and the support beam 67 where a step is generated. The electrode 70 is not disconnected. For this reason, between the part provided in the support part 65 among the movable side metal electrodes 70, and the movable side drive electrode 74 can be connected reliably.

  On the other hand, in the first substrate forming step shown in FIG. 25, an insulating glass substrate 99 to be the first substrate 62 of the switch element 61 is prepared. And after forming a through hole in the glass substrate 99 using a laser processing, a microblast method, etc., it fills with conductive metal materials, such as copper, by this plating in this through hole. Thereafter, the conductive metal material protruding from the through hole is polished, and the front and back surfaces of the glass substrate 99 are smoothed. As a result, the signal extraction electrode 82 connected to the electrode 75 is formed on the glass substrate 99.

  Further, a conductive metal thin film such as copper is formed on the glass substrate 99 by using, for example, sputtering or vapor deposition. As a result, on the surface of the glass substrate 99, the fixed-side signal electrode 75 is formed at a position corresponding to the movable portion 66, and the first fixed-side metal electrode 79 is formed at a position corresponding to the support portion 65.

  Further, a silicon oxide film is formed on the surface of the fixed-side signal electrode 75 and patterned into a predetermined shape by etching or the like. Thereby, a plurality of stoppers 77 protruding upward are formed on the fixed-side signal electrode 75. On the other hand, a bonding electrode 80 made of gold or the like is formed on the surface of the fixed metal electrode 79. Through the above steps, the first substrate 62 including the fixed signal electrode 75, the first fixed metal electrode 79, and the like is formed.

  Next, in the first substrate bonding step shown in FIG. 26, the bonding electrode 80 of the first substrate 62 and the first movable metal electrode 69 of the silicon substrate 64 are thermocompression bonded. Specifically, the movable-side metal electrode 69 and the bonding electrode 80 are in close contact with each other while the movable-side metal electrode 69 and the bonding electrode 80 are heated at a predetermined temperature in a range of, for example, 200 ° C. to 400 ° C. A predetermined load (for example, a load of about 4 t with respect to a 4-inch wafer) is applied. As a result, the electrodes 69 and 80 are pressure bonded to each other, and the silicon substrate 64 is bonded and fixed to the first substrate 62. As a result, the movable portion 66 of the silicon substrate 64 is disposed at a position covering the fixed-side signal electrode 75 of the substrate 62, and the stopper 77 is sandwiched between the signal electrodes 73 and 75.

  In the first substrate bonding step, the protective substrate 100 is provided on the surface side of the silicon substrate 64, and the silicon substrate 64 is pressed toward the first substrate 62 from the surface side of the protective substrate 100. At this time, the protective substrate 100 may be a plate having a flat contact surface on the silicon substrate 64 side, and is formed of, for example, a silicon substrate or a glass substrate whose contact surface is mirror-polished. In addition, the protective substrate 100 is not limited to a single plate, and for example, as shown by a two-dot chain line in FIG. 26, a graphite sheet for absorbing unevenness of the plate may be stacked on the surface of the plate. Good. The protective substrate 100 can prevent the surface of the second movable-side metal electrode 70 before joining from being uneven. As a result, it is possible to prevent a bonding failure in a second substrate forming process, which will be described later, and to improve bonding quality such as airtightness and yield.

  On the other hand, in the second substrate forming step shown in FIG. 27, an insulating glass substrate 101 to be the second substrate 63 of the switch element 61 is prepared. Then, after a through hole penetrating in the thickness direction is formed in the glass substrate 101, the through hole is filled with a conductive metal material such as copper. Thereafter, the conductive metal material protruding from the through hole is polished, and the front and back surfaces of the glass substrate 101 are smoothed. As a result, driving lead electrodes 83 and 84 connected to the electrodes 81 and 76, respectively, are formed on the glass substrate 101.

  Next, the recessed portion 63A and the stopper 78 are formed by etching a predetermined portion of the back surface of the glass substrate 101. Then, a conductive metal thin film such as gold is formed on the glass substrate 101 by using, for example, sputtering or vapor deposition. As a result, on the back surface of the glass substrate 101, the fixed-side drive electrode 76 is formed in the recessed portion 63 </ b> A, and the second fixed-side metal electrode 81 is formed at a position corresponding to the support portion 65. Through the above steps, the second substrate 63 including the fixed drive electrode 76 and the second fixed metal electrode 81 is formed.

  Next, in the second substrate bonding step shown in FIG. 28, the fixed-side metal electrode 81 of the second substrate 63 and the second movable-side metal electrode 70 of the silicon substrate 64 are substantially the same as in the first substrate bonding step. And thermocompression bonding. As a result, the metal electrodes 70 and 81 are pressure-bonded to each other, and the second substrate 63 is bonded and fixed to the surface side of the silicon substrate 64. As a result, the movable portion 66 of the silicon substrate 64 is disposed at a position facing the fixed drive electrode 76 of the substrate 63, and the switch element 61 is completed.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. In the present embodiment, since the inclined portion 68 whose thickness dimension is gradually reduced from the support portion 65 toward the support beam 67 is formed on the silicon substrate 64, the support portion 65 and the support beam 67 are interposed between the support portion 65 and the support beam 67. A steep step is not formed, and the surface of the silicon substrate 64 is in a smoothly continuous state, for example. For this reason, for example, when the second movable-side metal electrode 70 is formed on the surface of the silicon substrate 64 by using a vapor deposition method or a sputtering method, the metal electrode is not formed on the end surface (side surface of the support beam, etc.) of the silicon substrate 64. In contrast, the second movable-side metal electrode 70 can be reliably electrically connected between the support portion 65 and the movable portion 66. Thereby, the disconnection does not occur in the middle of the second movable side metal electrode 70, and the second movable side metal electrode 70 can be reliably formed on the surface of the silicon substrate 64.

  In addition, since the movable portion 66 is formed in a shape protruding toward the first substrate 62 from the back surface of the support portion 65, the movable portion 66 is moved to the first substrate 62 as the protruding dimension of the movable portion 66 increases. The spring force of the support beam 67 that presses against is increased. For this reason, the spring force of the support beam 67 can be adjusted according to the protrusion dimension of the movable part 66.

  Further, since the movable portion 66 protrudes toward the first substrate 62, it is not necessary to protrude toward the second substrate 63, and the surface of the movable portion 66 is higher than the surface of the support portion 65. Recessed toward. For this reason, when the silicon substrate 64 is pressure bonded to the first substrate 62, even when the silicon substrate 64 is pressed against the first substrate 62 using a pressure plate as a pressure jig, the movable portion 66 does not protrude from the support portion 65 toward the second substrate 63 side. As a result, the movable portion 66 does not come into contact with the pressure plate, and damage to the movable portion 66 and the movable drive electrode 74 can be prevented.

  In the anisotropic etching step, the silicon substrate 90 is subjected to anisotropic etching, and the recessed portion 93 that is recessed from the remaining portion is formed in the portion corresponding to the movable portion 66 and the support beam 67 in the silicon substrate 90. An inclined wall surface can be formed around the depression 93. For this reason, when the silicon substrate 90 having the depressions 93 is etched in the thin portion forming step and the support portion 65, the support beam 67, and the movable portion 66 are formed, the silicon substrate 64 has the support beam from the support portion 65 to the support beam. An inclined portion 68 whose thickness dimension is gradually reduced toward 67 can be formed.

  Further, since the recessed portion 93 protrudes to the back side from the remaining portion corresponding to the supporting portion 65, when the movable portion 66 is formed by the recessed portion 93, the movable portion 66 is more than the first substrate 62 than the supporting portion 65. Protrusively toward. For this reason, the spring force of the support beam 67 can be adjusted in accordance with the protrusion dimension d2 of the recess 93.

  Furthermore, in the first substrate bonding step in which the first fixed-side metal electrode 79 of the first substrate 62 and the first movable-side metal electrode 69 of the silicon substrate 64 are bonded by pressure bonding, A protective member 100 is provided, and the silicon substrate 64 is pressurized toward the first substrate 62 via the protective member 100. For this reason, the second movable-side metal electrode 70 of the silicon substrate 64 can be protected by using the protection member 100, and the second movable-side metal electrode 70 is not damaged or uneven. As a result, even when the second substrate 63 is pressure bonded after the first substrate 62 is pressure bonded, the second movable side metal electrode 70 of the silicon substrate 64 is held flat and the second substrate 63 is held flat. It can be crimped to the second fixed-side metal electrode 81 of the substrate 63, and bonding failure can be prevented.

  In the fourth embodiment, anisotropic etching is performed only on the surface of the silicon substrate 64, and isotropic etching is performed on the back surface. However, the present invention is not limited to this, and an anisotropic etching may be performed on both surfaces of the silicon substrate 64. In this case, the first movable-side metal electrode 69 can also be connected over the whole, and a variable capacitance element similar to that of the first embodiment can be formed.

  In the first to third embodiments, the anisotropic etching is performed only on one surface (surface) of the silicon substrate 4. For example, the variable capacitance element 1 according to the first modification shown in FIG. As in the case of ′, a structure may be adopted in which anisotropic etching is performed on both surfaces of the silicon substrate 4 ′ to form the support beam 7 ′ at an intermediate position in the thickness direction of the silicon substrate 4 ′. Even in this case, like the other embodiments, the movable side signal electrode 13 can be strongly pressed against the fixed side signal electrode 15, and the stability against impact can be enhanced.

  Further, in each of the above embodiments, the recesses 3A and 63A are formed in the second substrate 3 and 63. However, the present invention is not limited to this. For example, like the variable capacitance element 1 ″ according to the second modification shown in FIG. 30, the movable portion 6 ″ is formed thinner than the support portion 5 ″ so that the back surface is flat. The second substrate 3 ″ in the shape may be used. In this case, the etching of the silicon substrate 4 ″ can be performed with higher accuracy than the processing of the recessed portion in the second substrate 3 ″ made of a glass material. For this reason, the movable range of movable part 6 '' can be set correctly.

  Further, in the first to third embodiments, the first and second movable-side metal electrodes 9 and 10 are provided over the entire surface of the silicon substrate 4. However, the present invention is not limited to this, and it is not necessarily required to be provided over the entire surface as long as the sealed space for accommodating the movable portion 6 can be defined between the first and second substrates 2 and 3. Therefore, for example, one of the left and right support beams 7 may be configured to omit the first and second movable-side metal electrodes 9 and 10.

1,1 ', 1 "variable capacitance element (MEMS switch element)
2,62 First substrate 3,63 Second substrate 4,64,4 ', 4 "Silicon substrate 5,65,5', 5" Support portion 6,66,6 ', 6 "Movable portion 7,67 , 7 ', 7 "Support beam 8, 68, 8', 8" Inclined portion 9, 69 First movable side metal electrode 10, 70 Second movable side metal electrode 11, 71 First insulating film 12, 72 Second insulating film 13, 73 Movable signal electrode 14, 74 Movable drive electrode 15, 42, 75 Fixed signal electrode 16, 76 Fixed drive electrode 19, 20, 81 Fixed metal electrode 21, 22, 43, 82 Signal extraction electrode (Signal via hole)
23, 24, 83, 84 Lead electrode for driving (via hole for driving)
41, 61 switch element (MEMS switch element)
51 Relay element (MEMS switch element)
52 Contact part

Claims (7)

A silicon substrate sandwiched between first and second substrates;
A support formed on the silicon substrate and fixed to the first and second substrates;
A movable part formed on the silicon substrate and supported by the support part so as to be displaceable in the thickness direction using a support beam;
A fixed-side signal electrode provided on the first substrate and disposed at a position facing the movable portion of the silicon substrate;
A MEMS switch element comprising a fixed drive electrode provided on the second substrate and disposed at a position facing the movable portion of the silicon substrate,
The silicon substrate is formed with a thickness dimension of the support beam smaller than a thickness dimension of the support portion and the movable portion,
In the silicon substrate, an inclined portion whose thickness dimension is gradually reduced from the support portion toward the support beam, and an inclined portion whose thickness dimension is gradually reduced from the movable portion toward the support beam,
A conductive metal material is attached to both sides in the thickness direction of the silicon substrate from the direction perpendicular to both sides of the silicon substrate by vapor deposition or sputtering, so that the first and second substrates are adhered to each other. Forming opposing first and second movable metal electrodes,
Between the silicon substrate and the first and second movable-side metal electrodes, first and second insulating films are provided,
The first movable side metal electrode is formed with a movable side signal electrode which is located in a portion of the movable portion facing the fixed side signal electrode and is close to or away from the fixed side signal electrode.
The second movable side metal electrode is formed with a movable side drive electrode for applying an electrostatic force between the movable portion and the fixed side drive electrode, located at a portion facing the fixed side drive electrode. And
On the first substrate, a first fixed-side metal electrode made of a conductive metal material in contact with the first movable-side metal electrode is formed, and the first movable-side metal electrode and the first movable-side metal electrode are formed. Crimping the fixed side metal electrode,
The second substrate is formed with a second fixed-side metal electrode made of a conductive metal material in contact with the second movable-side metal electrode, and the second movable-side metal electrode and the second movable-side metal electrode. Crimping the fixed side metal electrode,
A stopper is provided between the fixed drive electrode and the movable drive electrode to prevent contact between the fixed drive electrode and the movable drive electrode.
The first substrate is provided with a signal via hole electrically connected to the fixed-side signal electrode,
The second substrate is provided with a drive via hole electrically connected to the fixed drive electrode and another drive via hole electrically connected to the second fixed metal electrode. A MEMS switch element having a configuration. A silicon substrate sandwiched between first and second substrates;
A support formed on the silicon substrate and fixed to the first and second substrates;
A movable part formed on the silicon substrate and supported by the support part so as to be displaceable in the thickness direction using a support beam;
A fixed-side signal electrode provided on the first substrate and disposed at a position facing the movable portion of the silicon substrate;
A MEMS switch element comprising a fixed drive electrode provided on the second substrate and disposed at a position facing the movable portion of the silicon substrate,
The silicon substrate is formed with a thickness dimension of the support beam smaller than a thickness dimension of the support portion and the movable portion,
In the silicon substrate, an inclined portion whose thickness dimension is gradually reduced from the support portion toward the support beam is formed,
In a state before the support portion is fixed to the first substrate, the movable portion protrudes toward the first substrate from the back surface of the support portion, and is recessed from the front surface of the support portion. Forming,
A conductive metal material is attached to both sides in the thickness direction of the silicon substrate from the direction perpendicular to both sides of the silicon substrate by vapor deposition or sputtering, so that the first and second substrates are adhered to each other. Forming opposing first and second movable metal electrodes,
Between the silicon substrate and the first and second movable-side metal electrodes, first and second insulating films are provided,
The first movable side metal electrode is formed with a movable side signal electrode which is located in a portion of the movable portion facing the fixed side signal electrode and is close to or away from the fixed side signal electrode.
The second movable side metal electrode is formed with a movable side drive electrode for applying an electrostatic force between the movable portion and the fixed side drive electrode, located at a portion facing the fixed side drive electrode. And
On the first substrate, a first fixed-side metal electrode made of a conductive metal material in contact with the first movable-side metal electrode is formed, and the first movable-side metal electrode and the first movable-side metal electrode are formed. Crimping the fixed side metal electrode,
The second substrate is formed with a second fixed-side metal electrode made of a conductive metal material in contact with the second movable-side metal electrode, and the second movable-side metal electrode and the second movable-side metal electrode. Crimping the fixed side metal electrode,
A stopper is provided between the fixed drive electrode and the movable drive electrode to prevent contact between the fixed drive electrode and the movable drive electrode.
The first substrate is provided with a signal via hole electrically connected to the fixed-side signal electrode,
The second substrate is provided with a drive via hole electrically connected to the fixed drive electrode and another drive via hole electrically connected to the second fixed metal electrode. A MEMS switch element having a configuration. The first and second movable metal electrodes are formed over the entire surface of the silicon substrate,
The first and second insulating films are formed over the entire surface of the silicon substrate;
The thickness dimension of the first movable side metal electrode and the fixed side signal electrode is set to a value larger than the thickness of the skin due to the propagating high frequency signal,
The thickness dimension of the second movable side metal electrode is set to a value that cancels out the warp generated in the movable part due to the difference in the linear expansion coefficient between the first movable side metal electrode and the silicon substrate. The MEMS switch element according to claim 1 or 2.   The structure according to claim 1, 2 or 3, wherein another stopper is provided between the fixed signal electrode and the movable signal electrode to prevent contact between the fixed signal electrode and the movable signal electrode. MEMS switch element.   3. A contact portion made of a conductive material that electrically connects the fixed-side signal electrode and the movable-side signal electrode is provided between the fixed-side signal electrode and the movable-side signal electrode. Or the MEMS switch element of 3. A silicon substrate sandwiched between first and second substrates, a support portion formed on the silicon substrate and fixed to the first and second substrates, and a support beam formed on the silicon substrate and using a support beam A movable part supported to be displaceable in the thickness direction, a fixed-side signal electrode provided on the first substrate and disposed at a position facing the movable part of the silicon substrate, and the second substrate. A MEMS switch element manufacturing method comprising: a fixed drive electrode provided at a position facing a movable portion of the silicon substrate,
An anisotropic etching process is performed on the silicon substrate before processing, and a recessed portion protruding from the back surface of the remaining portion is recessed from the surface of the remaining portion in the portion corresponding to the movable portion and the support beam in the silicon substrate. Forming, and
Etching the silicon substrate having the depression, and forming the support portion, the support beam, and the movable portion;
A conductive metal material is attached to both surfaces of the silicon substrate having the support portion, the support beam, and the movable portion in the thickness direction from the direction perpendicular to the both surfaces of the silicon substrate using a vapor deposition method or a sputtering method, Forming first and second movable metal electrodes facing the first and second substrates, respectively;
Forming the fixed-side signal electrode on the first substrate, and forming a first fixed-side metal electrode made of a conductive metal material in contact with the first movable-side metal electrode;
Forming the fixed drive electrode on the second substrate and forming a second fixed metal electrode made of a conductive metal material in contact with the second movable metal electrode;
Pressure bonding the first fixed metal electrode of the first substrate and the first movable metal electrode of the silicon substrate;
A method for manufacturing a MEMS switch element, comprising: a step of pressure-bonding a second fixed-side metal electrode of the second substrate and a second movable-side metal electrode of the silicon substrate.   In the step of pressure bonding the first fixed-side metal electrode of the first substrate and the first movable-side metal electrode of the silicon substrate, the first side of the silicon substrate facing the second substrate 7. The method of manufacturing a MEMS switch element according to claim 6, wherein a protective member for protecting the two fixed-side metal electrodes is provided, and the silicon substrate is pressed toward the first substrate through the protective member. .

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