JP2008096620A - Micromirror, mems with micromirror mounted thereon, and method of manufacturing mems - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micromirror having a simple structure of a movable mirror having a large degree of freedom of two-axes rotation with a high packing ratio, a MEMS with the micromirror mounted thereon, and a method of manufacturing the MEMS at a low cost, in order to solve the problem that a micromirror having the conventional high packing ratio movable mirror is limited in the movable directions of the movable mirror, and a complicated structure is necessary to avoid the problem and the cost is increased. <P>SOLUTION: The micromirror of the present invention has a structure in which three flat plates are arranged between two supporting points and connected by hinges and the hinges for two axes-rotation are used on both ends of the central flat plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a micromirror in which movable mirrors capable of biaxial rotation can be arranged at high density, a MEMS having the micromirror mounted thereon, and a method of manufacturing the MEMS.

  2. Description of the Related Art In recent years, MEMS (Micro Electro Mechanical Systems) that include a micromirror having a movable mirror and that can control the tilt angle of the movable mirror have been developed as optical devices. For example, when the MEMS is an optical switch, the inclination angle of the mirror surface of the movable mirror is changed depending on whether or not a voltage is applied to an electrode on the back side of the movable mirror, and two states of “ON” and “OFF” Can be given. Since the reflection direction of the incident light is different between “ON” and “OFF”, if the optical fiber is arranged in the reflection direction of the light incident on the movable mirror at “ON”, the light irradiated on the movable mirror is When it is “ON”, it is coupled to the optical fiber. When it is “OFF”, it is not coupled to the optical fiber.

  Furthermore, a micro-mirror MEMS in which a large number of movable mirrors are arranged in a plane has been developed. Such MEMS can be used as a wavelength selective switch. When the wavelength multiplexed light transmitted through the optical fiber is diffracted by a dispersion element such as a bulk grating, a spot array according to the wavelength permutation is obtained. By irradiating the surface of the micromirror with the spot array and applying a voltage to the electrode of the movable mirror of the micromirror irradiated with light of a desired wavelength, any one of the plurality of optical fibers Can be selectively optically coupled. In such a wavelength selection switch, if the distance between the movable mirrors is large, a wavelength region that cannot be selected is generated. Therefore, it is necessary to arrange the movable mirrors without any gaps. For this reason, a micromirror MEMS having a small movable mirror interval has been developed (see, for example, Patent Document 1).

4A of Patent Document 1 includes a micromirror having a structure in which one end in the longitudinal direction (vertical direction) of a movable mirror is connected to a fulcrum by a biaxial rotating hinge and the other end in the longitudinal direction of the movable mirror is connected to a cantilever. A MEMS is disclosed. Since the biaxial rotation of the movable mirror is possible by providing the biaxial rotating hinge and the cantilever, the fulcrum in the horizontal direction is unnecessary and the MEMS can be arranged in parallel. Therefore, the distance between the movable mirrors can be reduced. The interval between the movable mirrors is represented by a filling ratio obtained by dividing the sum of the areas of the movable mirrors by the sum of the areas of the gaps between the movable mirrors.
International Publication No. 04/094301 Pamphlet

  However, the MEMS described in FIG. 4A of Patent Document 1 has a problem that the degree of freedom of rotation of the movable mirror is limited because the drive direction of the cantilever is only on the electrode side (downward). Further, in order to avoid the limitation, it is necessary to dispose an electrode for driving the cantilever upward on the micromirror as in the MEMS disclosed in FIG. 4B, and the structure is complicated and the manufacturing cost increases. There was a problem.

  Therefore, in order to solve such problems, the present invention provides a micromirror having a simple structure having a movable mirror having a high degree of freedom of biaxial rotation at a high filling ratio, a MEMS on which the micromirror is mounted, and a MEMS at a low cost. It aims at providing the manufacturing method which can be manufactured.

  In order to achieve the above object, the micromirror according to the first invention of the present application has a structure in which three flat plates arranged between two fulcrums are connected by hinges, and biaxial rotation is provided at both ends of the central flat plate. A hinge that can be used is used.

  Specifically, the first invention of the present application includes a first flat plate arranged in order between a first fulcrum and a second fulcrum, a second flat plate and a third flat plate whose one surface is a mirror surface, A first hinge connecting the fulcrum and the edge of the first flat plate, parallel to the surface of the first flat plate and having a rotation axis in a direction perpendicular to the direction of the second fulcrum from the first fulcrum; The edge of the first flat plate and the edge of the second flat plate on the opposite side of the first hinge are connected, and the direction parallel to the rotation axis of the first hinge is from one rotation axis and the first fulcrum. A second hinge having another rotation axis in a direction parallel to the direction of the second fulcrum, and an edge of the second flat plate opposite to the second hinge and an edge of the third flat plate; A direction parallel to the rotation axis of the first hinge is a rotation axis and a direction parallel to the direction of the second fulcrum from the first fulcrum is the other rotation axis. A hinge and a fourth hinge connecting the edge of the third flat plate opposite to the third hinge and the second fulcrum and having a rotation axis in a direction parallel to the rotation axis of the first hinge; And a micromirror having a structure in which the second flat plate is rotated biaxially.

  The micromirror according to the first invention of the present application is a simple one in which the first flat plate, the second flat plate, and the third flat plate arranged between the first fulcrum and the second fulcrum are connected by the first hinge to the fourth hinge, respectively. It is formed with a simple structure. In the following explanation, “the straight line connecting the first fulcrum and the second fulcrum” is “the central axis of the micromirror”, “the direction from the first fulcrum to the second fulcrum” is “vertical direction”, A direction parallel to the surface of one flat plate and perpendicular to the longitudinal direction will be described as a “lateral direction”.

  The first hinge has the horizontal direction as a rotation axis, and the connected first flat plate can be easily rotated in the normal direction of the surface of the first flat plate. Hereinafter, the rotation direction of the first hinge and the first flat plate will be described as the θz direction. Similarly, the fourth hinge can rotate the third flat plate in the θz direction.

  The second hinge and the third hinge can be rotated not only in the θz direction but also in a direction having the longitudinal direction as a rotation axis. Hereinafter, the rotation direction of the second hinge and the third hinge with the vertical direction as the rotation axis will be described as the θx direction. Since both ends of the second flat plate are connected by the second hinge and the third hinge, the second flat plate can rotate in the θx direction about a straight line connecting the connection point of the second hinge and the connection point of the third hinge. it can.

  Further, the second flat plate is connected to the first flat plate by the second hinge and is connected to the third flat plate by the third hinge. Therefore, when the first flat plate rotates in the θz direction and the third flat plate does not rotate, the second hinge side of the second flat plate is pulled in the rotation direction of the first flat plate by the second hinge and rotates in the θz direction. On the other hand, since the third flat plate does not rotate on the third hinge side of the second flat plate, the second flat plate is inclined to the first flat plate side because the rotation in the θz direction and the bending due to this do not occur. Conversely, when the first flat plate is not rotated and the third flat plate is rotated, the second flat plate is inclined to the third flat plate side. That is, by adjusting the magnitude of rotation of the first flat plate and the second flat plate, the second flat plate can be rotated in the θz direction, and the degree of freedom of rotation is large.

  That is, the second flat plate whose one surface is a mirror surface functions as a movable mirror capable of biaxial rotation in the θx direction and the θz direction. In addition, since the micromirror according to the first invention of the present application is supported by the first fulcrum and the second fulcrum in the vertical direction and does not have a fulcrum in the horizontal direction, the micromirrors are arranged in the horizontal direction without gaps, so that the movable mirror It is possible to increase the filling ratio of the second flat plate.

  Therefore, the first invention of the present application can provide a micromirror having a simple structure having a movable mirror having a high degree of freedom of biaxial rotation at a high filling ratio.

  Further, the first hinge and the fourth hinge of the micromirror according to the first invention of the present application have a spring hinge structure that meanders in a direction parallel to the rotation axis of the first hinge, and the second hinge and the second hinge The three hinges have a spring hinge structure in which a portion meandering in a direction parallel to one rotation axis of the second hinge and a portion meandering in a direction parallel to the other rotation axis of the second hinge are connected. preferable.

  By having a spring hinge structure from the first hinge to the fourth hinge, the micromirror can be manufactured from a single silicon substrate. For this reason, the first flat plate to the third flat plate and the first hinge to the fourth hinge can be integrally formed without being manufactured separately, and the manufacture becomes easy. Therefore, the spring hinge structure from the first hinge to the fourth hinge has the effect of reducing the manufacturing cost in addition to the above-described effects.

  The second invention of the present application is a micromirror according to the first invention of the present application, a first support to which the first fulcrum of the micromirror is fixed, and a second support to which the second fulcrum of the micromirror is fixed. On the same surface, and a substrate on which the micromirror is bridged between the first support and the second support, wherein the substrate is the first support A first electrode plate disposed at a position opposite to the first flat plate on the surface to be mounted and generating an electrostatic force between the first flat plate and an applied voltage; and a surface on which the first support is mounted A second electrode plate and a third electrode that are arranged in parallel in the direction from the first fulcrum to the second fulcrum at a position facing the second flat plate, and generate an electrostatic force between the second flat plate and an applied voltage. The plate and the surface on which the first support is mounted A fourth electrode plate disposed at a position opposite to the three flat plates and generating an electrostatic force between the third flat plate by an applied voltage, and further mounted from the first electrode plate to the fourth electrode plate The MEMS has a function of tilting the mirror surface of the second flat plate to a desired angle by biaxially rotating the second flat plate with an applied voltage.

  The MEMS has a structure in which the micromirror according to the first invention of the present application is bridged between the first support and the second support of the substrate. As described in the first invention, there is a space between the micromirror and the substrate, and the first flat plate, the second flat plate, and the third flat plate of the micromirror are stretched over the substrate. Can work. The surface on the substrate side from the first flat plate to the third flat plate will be described as the back surface, and the surface opposite to the back surface of the first flat plate from the third flat plate will be described as the front surface.

  Furthermore, the substrate mounts the fourth electrode plate from the first electrode plate. The first electrode plate is disposed at a position facing the back surface of the first flat plate, and the fourth electrode plate is disposed at a position facing the back surface of the third flat plate. The second electrode plate is arranged at a position facing one side of the back surface of the second flat plate divided by the central axis of the micromirror. A 3rd electrode is arrange | positioned in the position facing the other side divided by the central axis of a micromirror among the back surfaces of a 2nd flat plate.

  When a voltage is applied to the first electrode, an electrostatic attractive force is generated between the first flat plate and the first flat plate rotates in the θz direction. Similarly, when a voltage is applied to the fourth electrode, the third flat plate rotates in the θz direction. That is, the second flat plate can be rotated in the θz direction by the voltage applied to the first electrode and the fourth electrode, and the rotation angle can be controlled.

  When a voltage is applied to the second electrode, an electrostatic attractive force is generated between one side of the second flat plate divided by the central axis of the micromirror, and the second flat plate rotates in the θx direction. Similarly, even if a voltage is applied to the third electrode, the second flat plate rotates in the θx direction. That is, the second flat plate can be rotated in the θx direction by the voltage applied to the second electrode and the third electrode, and the rotation angle can be controlled.

  By making the width in the horizontal direction of the substrate and the width in the horizontal direction of the second flat plate substantially equal and arranging the MEMS in the horizontal direction with no gap, the filling ratio of the second flat plate, which is a movable mirror, can be increased.

  Therefore, the second invention of the present application can provide a MEMS having a simple structure on which a micromirror having a simple structure having a movable mirror having a high degree of freedom of biaxial rotation at a high filling ratio.

  Moreover, although the MEMS provided with the said board | substrate for every micromirror was demonstrated, you may bridge a some micromirror on one board | substrate.

  Specifically, the third invention of the present application includes a plurality of micromirrors of the first invention of the present application that are arranged in parallel so that the mirror surfaces of the second flat plate are arranged in a plane, and A first support to which the first fulcrum is fixed and a second support to which the second fulcrum of the micromirror is fixed are mounted on the same surface, and the first support and the second support A substrate on which a plurality of the micromirrors are bridged, wherein the substrate is located at a position facing the first flat plate on the surface on which the first support is mounted for each micromirror. A first electrode plate that is arranged and generates an electrostatic force between the first flat plate and an applied voltage, and the first fulcrum at a position facing the second flat plate on the surface on which the first support is mounted. Arranged in parallel in the direction of the second fulcrum, A second electrode plate and a third electrode plate that generate an electrostatic force between the second flat plate by voltage, and a position opposite to the third flat plate on the surface on which the first support is mounted and applied A fourth electrode plate for generating an electrostatic force between the third flat plate and a voltage applied to the microelectrode by the voltage applied from the first electrode plate to the fourth electrode plate for each micromirror. The MEMS may have a function of tilting the mirror surface of the second flat plate at a desired angle by biaxially rotating the second flat plate for each mirror.

  On the substrate, the first electrode plate to the fourth electrode plate are arranged at positions facing the back surface of the third flat plate from the first flat plate of each micromirror. Therefore, the MEMS according to the third invention can rotate the second flat plate of each micromirror biaxially as described in the second invention. Further, the filling ratio of the second flat plate, which is a movable mirror, can be increased by laying the micromirrors on the substrate without gaps in the lateral direction.

  Accordingly, the third invention of the present application is a MEMS having a simple structure in which a micromirror having a simple structure having a movable mirror having a high degree of freedom of biaxial rotation at a high filling ratio is mounted, similar to the MEMS according to the second invention. Can be provided.

  A fourth invention of the present application includes a micromirror forming step of forming the micromirror of the first invention of the present application from a silicon plate, a first support body on which the first fulcrum of the micromirror is fixed to a base substrate, and the micro Forming a second support to which the second fulcrum of the mirror is fixed, and causing the first electrode plate to generate an electrostatic force between the first plate and the first plate by the applied voltage is opposed to the first plate of the micromirror; The second electrode plate and the third electrode plate, which are arranged at positions and generate an electrostatic force between the second flat plate by an applied voltage, from the first fulcrum to a position facing the second flat plate of the micromirror Arranging in parallel in the direction of the second fulcrum, arranging a fourth electrode plate for generating an electrostatic force between the third plate and the applied voltage at a position facing the third plate of the micromirror, From base board Forming the substrate, the first fulcrum of the micromirror formed in the micromirror formation step, the first support of the substrate formed in the substrate formation step, and the micromirror formation step Bonding the second fulcrum of the micromirror formed in step 2 and the second support of the substrate formed in the substrate forming step, and bonding the micromirror to the substrate. It is the MEMS manufacturing method characterized.

  In the MEMS manufacturing method according to the fourth invention of the present application, the micromirror and the substrate are prepared separately, and they are bonded together. In a conventional MEMS manufacturing method, after a movable part is processed into a structure, a structure is released by isotropically etching a sacrificial layer therebelow. For example, a surface micromachining process in which an additional layer is added to the silicon surface to remove the support layer as a sacrificial layer, or a deep RIE (Reactive Ion Etching) process using an SOI (Silicon on Insulator) substrate. A method is known in which, after a body is processed, an oxide film layer is etched as a sacrificial layer using a silicon oxide film sacrificial layer dry etching apparatus or the like. Since there is no such complicated process, the MEMS manufacturing method according to the fourth invention of the present application can easily manufacture the MEMS according to the second invention or the third invention.

  Therefore, 4th invention of this application can provide the MEMS manufacturing method which can manufacture MEMS which concerns on 2nd invention or 3rd invention at low cost.

  According to the present invention, the present invention is a micromirror having a simple structure having a movable mirror having a high degree of freedom of biaxial rotation at a high filling ratio, a MEMS on which the micromirror is mounted, and a manufacturing capable of manufacturing the MEMS at a low cost. A method can be provided.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments.

(Embodiment 1)
In the present embodiment, a first flat plate arranged in order between a first fulcrum and a second fulcrum, a second flat plate and a third flat plate whose one surface is a mirror surface, the first fulcrum and the first flat plate A first hinge having a rotation axis in a direction parallel to the surface of the first flat plate and perpendicular to the direction from the first fulcrum to the second fulcrum, and opposite to the first hinge The edge of the first flat plate and the edge of the second flat plate are connected, and a direction parallel to the rotation axis of the first hinge is defined as one rotation axis and the direction from the first fulcrum to the second fulcrum. A second hinge having a parallel direction as another axis of rotation, and an edge of the second plate opposite to the second hinge and an edge of the third plate are connected, and the axis of rotation of the first hinge A third hinge having a direction parallel to the first rotation axis and a direction parallel to the direction of the second fulcrum from the first fulcrum to the other rotation axis; A fourth hinge connecting the edge of the third flat plate opposite to the three hinges and the second fulcrum, and having a rotation axis in a direction parallel to the rotation axis of the first hinge; This is a micromirror having a structure in which two flat plates are rotated biaxially.

  FIG. 1 is a diagram showing a configuration of a micromirror 101 which is one embodiment of the first invention of the present application. The micro mirror 101 includes a first flat plate 21, a second flat plate 22, a third flat plate 23, a first hinge 31, a second hinge 32, a third hinge 33 and a fourth hinge 34.

  The first flat plate 21, the second flat plate 22, and the third flat plate 23 are formed of silicon or SOI (silicon on insulator). In order to increase the filling rate as will be described later, the shape from the upper surface is preferably rectangular, and the lateral width is preferably equal. Further, since the second flat plate functions as a movable mirror, the surface is coated with a highly reflective metal coating such as gold or aluminum.

  The first hinge 31 and the fourth hinge 34 are hinges having one axis, and the connected objects at both ends can be rotated around the axis. A specific structure of the first hinge 31 is shown in FIG. As shown in FIG. 2, the first hinge 31 has a spring hinge structure that meanders in a direction (lateral direction) perpendicular to a direction connecting the connection point 1A and the connection point 2A at both ends. Since the lateral spring hinge bends in the θz direction, the first hinge 31 can rotate in the θz direction. With the spring hinge structure as shown in FIG. 2, the material of the first hinge 31 can be formed of silicon or SOI, and can be integrated with the first flat plate 21, the second flat plate 22, and the third flat plate 23. it can.

  The fourth hinge 34 has the same structure as the first hinge 31 and functions in the same manner. As dimensions of the spring hinges of the first hinge 31 and the fourth hinge 34, for example, the width is 1.5 μm, the gap is 1.5 μm, and the thickness is 7.5 μm.

  The second hinge 32 and the third hinge 33 are hinges having two orthogonal axes, and the connected objects at both ends can be rotated about the two axes by two axes. A specific structure of the second hinge 32 is shown in FIG. As shown in FIG. 3, the second hinge 32 meanders in a direction (longitudinal direction) parallel to the direction connecting the connecting point 3a between the connecting point 3A and the connecting point 4A in the lateral direction and the connecting point at both ends. 32b is a spring hinge structure connected to 32b. Since the portion 32a bends in the θz direction and the portion 32b bends in the θx direction, the second hinge 32 can be rotated biaxially in the θz direction and the θx direction. By adopting the spring hinge structure as shown in FIG. 3, the first flat plate 21, the second flat plate 22, and the third flat plate 23 can be integrated as in the description of the first hinge 31 of FIG. 2.

  The third hinge 33 has the same structure as the second hinge 32 and functions in the same manner. As the dimensions of the spring hinges of the second hinge 32 and the third hinge 33, the dimensions described in the first hinge 31 of FIG.

  The micromirror 101 is configured by connecting the first hinge 31, the first flat plate 21, the second hinge 32, the second flat plate 22, the third hinge 33, the third flat plate 23, and the fourth hinge 34 in this order as described below. Is done. The connection point 2A of the first hinge 31 and one end of the first flat plate 21 are connected. The other end of the first flat plate 21 and the connection point 3A of the second hinge 32 are connected. The connection point 4A of the second hinge 32 and one end of the second flat plate 22 are connected. The other end of the second flat plate 22 and the connection point 4A of the third hinge 33 are connected. The connection point 3A of the third hinge 33 and one end of the third flat plate 23 are connected. The other end of the third flat plate 23 and the connection point 1A of the fourth hinge 34 are connected. In the above description, the other end of the third flat plate 23 and the connection point 1A of the fourth hinge 34 are connected. However, the other end of the third flat plate 23 and the connection point 2A of the fourth hinge 34 are connected. However, the same effect can be obtained.

  The connection point 1A of the first hinge 31 is a first fulcrum, and the connection point 2A of the fourth hinge 34 is a second fulcrum. The connection point between each flat plate and the hinge is preferably on the central axis of the micromirror 101. This is because the second flat plate 22 is rotated as the central axis of the micromirror 101. The first hinge 31 and the fourth hinge 34 and the second hinge 32 and the third hinge 33 are preferably rotationally symmetric with respect to the center of the second flat plate 22. As a result, a well-balanced biaxial rotation operation is possible.

  Note that the second hinge 32 and the third hinge 33 may be arranged in opposite directions. Specifically, the other end of the first flat plate 21 and the connection point 4A of the second hinge 32 are connected. The connection point 3A of the second hinge 32 and one end of the second flat plate 22 are connected. The other end of the second flat plate 22 and the connection point 3A of the third hinge 33 are connected. The connection point 4A of the third hinge 33 and one end of the third flat plate 23 are connected. The second hinge 32 and the third hinge 33 are preferably rotationally symmetric with respect to the center of the second flat plate 22. Even in such a connection, the micromirror 101 has the same function.

  The micromirror 101 can be supported only by the first fulcrum and the second fulcrum in the vertical direction, and there is no fulcrum in the horizontal direction of the micromirror 101. Therefore, a plurality of micromirrors 101 can be brought into close contact with each other and arranged in parallel, and the filling rate of the second flat plate 22 that is a movable mirror can be increased.

  In order to use the micromirror 101 as an optical switch or the like, it is necessary to further include a mechanism for driving the second flat plate 22 to be a MEMS.

  Specifically, the micromirror according to the first aspect of the present invention is the same as the first support to which the first fulcrum of the micromirror is fixed and the second support to which the second fulcrum of the micromirror is fixed. And a substrate on which the micromirror is bridged between the first support and the second support, wherein the substrate is mounted with the first support. A first electrode plate that is disposed at a position opposite to the first flat plate on the surface and generates an electrostatic force between the first flat plate and an applied voltage; and the first electrode plate on the surface on which the first support is mounted. A second electrode plate and a third electrode plate, which are arranged in parallel in the direction from the first fulcrum to the second fulcrum at a position facing the two flat plates, and generate an electrostatic force between the second flat plate by an applied voltage; The third flat surface of the surface on which the first support is mounted. And a fourth electrode plate that generates an electrostatic force between the third plate and the third plate by an applied voltage, and is applied from the first electrode plate to the fourth electrode plate. The MEMS has a function of rotating the second flat plate biaxially by a voltage to tilt the mirror surface of the second flat plate to a desired angle.

  FIG. 4 is a diagram showing a configuration of a MEMS 901 which is one embodiment of the second invention of the present application. The MEMS 901 includes a micromirror 101 and a substrate 401. 4, the same reference numerals as those used in FIGS. 1 to 3 indicate the same parts and the same parts.

  The first support body 41 or the second support body 42 is mounted on the end in the longitudinal direction of the substrate 401. Further, the first electrode plate 51, the second electrode plate 52, the third electrode plate 53, and the fourth electrode plate 54 are mounted on the surface of the substrate 401 on the side where the first support body 41 and the second support body 42 are mounted. Is done. The substrate 401 on which the first support 41 and the second support 42 are mounted is formed of silicon or ceramic.

  The MEMS 901 has a structure in which the first fulcrum of the micromirror 101 is connected to the first support 41 of the substrate 401 and the second fulcrum is connected to the second support 42 of the substrate 401. Specifically, the connection point 1A of the first hinge 31 and the first support body 41 are connected, and the connection point 2A of the fourth hinge 34 and the second support body 42 are connected. Since the first support body 41 and the second support body 42 have a predetermined height, the micromirror 101 is bridged between the first support body 41 and the second support body 42, and the first flat plate 21. A gap is generated between the second flat plate 22 and the third flat plate 23 and the substrate 401.

  Further, the first electrode plate 51, the second electrode plate 52, the third electrode plate 53, and the fourth electrode plate 54 on the surface of the substrate 401 are mounted as shown in FIG. FIG. 5 shows the substrate 401 before the micromirror 101 is bridged, as viewed from the side on which the first support 41 is mounted. In FIG. 5, the same reference numerals as those used in FIG. 4 indicate the same parts.

  The first electrode plate 51 is disposed at a position facing the back surface of the first flat plate 21 when the micromirror 101 is bridged. In addition, a voltage is applied to the first electrode plate 51 by a wiring (not shown), and an electrostatic attractive force is generated between the first electrode plate 51 and the first flat plate 21 by the applied voltage.

  The fourth electrode plate 54 is disposed at a position facing the back surface of the third flat plate 23 when the micromirror 101 is bridged. In addition, a voltage is applied to the fourth electrode plate 54 by a wiring (not shown), and an electrostatic attractive force is generated between the fourth electrode plate 54 and the third flat plate 23 by the applied voltage.

  The second electrode plate 52 and the third electrode plate 53 are arranged in parallel in a direction parallel to the central axis of the micromirror 101 at a position facing the back surface of the second flat plate 22 when the micromirror 101 is bridged. . Specifically, the second electrode plate 52 and the third electrode plate 53 are disposed on both sides of the center line in the longitudinal direction of the substrate 401. A voltage is applied to the second electrode plate 52 and the third electrode plate 53 by a wiring (not shown), and an electrostatic attractive force is generated between the second electrode plate 52 and the second plate 22 by the applied voltage.

  The rotation state of the second flat plate 22 of the MEMS 901 is shown in FIGS. 6A to 10B, (a) is a perspective view of the MEMS 901, and (b) is a side view of the MEMS 901 viewed from the lateral direction. In all the drawings, the same reference numerals as those used in FIGS. 1 to 5 indicate the same components. By applying a voltage from the first electrode plate 51 to the fourth electrode plate 54, the second flat plate 22 as shown in FIGS. 6 to 10 can be rotated. In any case, the driving force will be described as an electrostatic attractive force generated between the electrode and the first flat plate 21 to the third flat plate 23. In each figure, the first electrode plate 51 to the fourth electrode plate 54 are omitted. Also, in FIGS. 6 to 10, the degree of deformation of the drawings is exaggerated several times from the actual degree of deformation for easy understanding.

  FIG. 6 shows a case where a voltage is applied to the first electrode plate 51. An electrostatic attractive force F <b> 14 is applied to the first flat plate 21 in the direction of the substrate 401 due to an electrostatic force generated between the first flat plate 21 and the first electrode plate 51. Generally, electrostatic attraction is proportional to the square of the applied voltage and inversely proportional to the square of the electrode spacing. The first flat plate 21 to the third flat plate 23 rotate to reach an equilibrium state until the electrostatic attractive force F14 and the spring force of the first hinge 31 to the hinge spring of the fourth hinge 34 are balanced. Specifically, due to the electrostatic attractive force F14, the first flat plate 21 is inclined as shown in FIG. 6, and the second flat plate 22 is pulled by the second hinge 32 to generate a rotational force R15 in the θz direction as shown in FIG. . The inclination direction of the second flat plate 22 can be maintained by keeping the voltage applied to the first electrode plate 51 constant. Further, the magnitude of the rotational force R15 can be changed by the applied voltage. The direction of the rotational force R15 is the negative direction of the θz direction.

  FIG. 7 shows a case where a voltage is applied to the fourth electrode plate 54. As in the description of FIG. 6, an electrostatic attractive force F16 is applied to the third flat plate 23, and the second flat plate 22 generates a rotational force R17 in the positive direction of the θz direction as shown in FIG. As in the description of FIG. 6, this state can be maintained by continuously applying a constant voltage.

  FIG. 8 shows a case where a voltage is applied to the second electrode plate 52. Since an electrostatic attractive force F18 is applied to one side of the second flat plate 22, the second flat plate 22 generates a rotational force R19 in the θx direction as shown in FIG. The direction of the rotational force R19 is the negative direction of the θx direction. The inclination direction of the second flat plate 22 can be maintained by keeping the voltage applied to the second electrode plate 52 constant. Further, the magnitude of the rotational force R19 can be changed by the applied voltage.

  When the second flat plate 22 rotates in the θx direction, the first flat plate 21 and the third flat plate 23 also have a function of suppressing the rotational moment of the second flat plate 22.

  FIG. 9 shows a case where a voltage is applied to the third electrode plate 53. As in the description of FIG. 8, an electrostatic attractive force F20 is applied to one side of the second flat plate 22, and the second flat plate 22 generates a rotational force R21 in the positive direction of the θx direction as shown in FIG. As in the description of FIG. 8, this state can be maintained by continuously applying a constant voltage.

  FIG. 10 shows a case where a voltage is applied to the first electrode plate 51 and the second electrode plate 52. The second flat plate 22 is rotated biaxially by θx negative direction rotation and θz negative direction rotation. This state can be maintained by making both voltages constant. As described above, the inclination angle of the second flat plate 22 can be changed and fixed in an arbitrary direction by changing the voltage applied from the first electrode plate 51 to the fourth electrode plate 54.

  Although the MEMS 901 has a simple structure as described above, the movable mirror can be rotated biaxially, and the degree of freedom is higher than that of the conventional micromirror MEMS.

  Light reflected on the second flat plate 22 from a predetermined direction can be freely changed in its reflection direction. For example, if there is an optical fiber in the reflection direction, the reflected light is coupled to this optical fiber, so the MEMS 901 can be used as an optical switch. Also, the MEMS 901 can be used as a 1 × N optical switch by arranging a plurality of optical fibers and coupling the reflected light to a desired optical fiber. Further, if the inclination angle of the second flat plate 22 is slightly changed, the reflection direction changes, and the optical coupling efficiency to the optical fiber can be changed. As a result, the intensity of light coupled to the optical fiber can be changed, so that the MEMS 901 can be used as an optical attenuator.

  On the other hand, since the micromirror 101 is supported by the first support body 41 and the second support body 42 and there is no fulcrum for supporting the micromirror 101 in the horizontal direction, the MEMS 901 can be arranged in parallel in the horizontal direction without gaps. It is possible to increase the filling ratio of the flat plate 22.

  Therefore, although the micromirror 101 and the MEMS 901 have a simple structure, the degree of freedom of biaxial rotation of the movable mirror is large, and when arranged in parallel, the movable mirror can be arranged with a high filling ratio.

(Embodiment 2)
In the present embodiment, a plurality of the micromirrors of the first invention of the present application that are arranged in parallel so that the mirror surfaces of the second flat plate are arranged in a plane are fixed to the first fulcrum of the micromirror. A plurality of micromirrors between the first support and the second support, wherein the first support and the second support to which the second fulcrum of the micromirror is fixed are mounted on the same surface. Each of the micromirrors, the substrate is disposed at a position facing the first flat plate on the surface on which the first support is mounted, and is applied with an applied voltage. A first electrode plate for generating an electrostatic force between the first flat plate and a position facing the second flat plate on the surface on which the first support is mounted in the direction from the first fulcrum to the second fulcrum. Arranged in parallel, the applied voltage A second electrode plate and a third electrode plate for generating an electrostatic force between the two flat plates, and a surface on which the first support is mounted facing the third flat plate; A fourth electrode plate for generating an electrostatic force between the three flat plates; and the voltage applied to the fourth electrode plate from the first electrode plate to the fourth electrode plate for each micromirror. A MEMS having a function of rotating a second flat plate biaxially and inclining the mirror surface of the second flat plate at a desired angle.

  FIG. 11 is a diagram showing a configuration of a MEMS 902 which is one embodiment of the third invention of the present application. The MEMS 902 includes five micromirrors 101 and a substrate 402. In FIG. 11, the same reference numerals as those used in FIGS. 1 to 10 denote the same components. In the MEMS 902, the number of micromirrors 101 is not limited to five, and may be more or less.

  The substrate 402 is the same as the substrate 401 described with reference to FIGS. 4 and 5, but each micromirror 101 uses the first support 41 and the second support 42 as a common first fulcrum and second fulcrum. ing. Specifically, the connection point 1A of the first hinges 31 of all the micromirrors 101 is connected to the first support 41, and the connection point of the fourth hinges 34 of all the micromirrors 101 to the second support 42. 2A is connected.

  Since there is no fulcrum in the horizontal direction of the micromirror 101, the micromirror 101 can be bridged across the substrate 402 in the horizontal direction without gaps, and the MEMS 902 can increase the filling ratio of the second flat plate 22.

  Furthermore, in order to bridge five micromirrors 101, the first electrode plate 51, the second electrode plate 52, the third electrode plate 53, and the fourth electrode plate 54 are disposed on the substrate 402 at positions corresponding to the respective micromirrors 101. Installed. Therefore, as described in the MEMS 901 in FIGS. 6 to 10, the MEMS 902 can also rotate each second flat plate 22 biaxially by applying a voltage to each electrode plate.

  For example, when the width of the adjacent second flat plate 22 is 100 μm and the gap is 2 μm, a high filling ratio of 98% or more can be realized. Wavelength multiplexed light from the input fiber is diffracted by the bulk grating, and light of each wavelength is irradiated on each mirror surface of the second plate 22 in order of wavelength. By changing the direction of the light beam reflected by the mirror, the reflected beam can be coupled to an arbitrary optical fiber among a plurality of optical fibers, and can be used as a wavelength selective switch. In general, light of each wavelength in the wavelength division multiplexed light has a certain wavelength width, and the center wavelength may vary in the band band. As described above, when the center wavelength of the light of each wavelength varies, the light spot on each MEMS mirror moves in the horizontal direction from side to side depending on the direction of wavelength variation. Here, when a MEMS mirror array having a low filling ratio is used, a wavelength region that cannot be sufficiently reflected by spot movement occurs. Since the MEMS mirror array having a high filling ratio can reflect the entire band band, the MEMS 902 can be used as an optical wavelength selective switch having a wide bandwidth and a flat loss characteristic.

  Therefore, the MEMS 902 has a simple structure but has a high degree of freedom in biaxial rotation of the movable mirror, and the movable mirror can be arranged with a high filling ratio.

  The MEMS 902 includes a micromirror forming step of forming the micromirror of the first invention of the present application from a silicon plate, a first support on which the first fulcrum of the micromirror is fixed to a base substrate, and the first of the micromirror. A first electrode plate that forms a second support to which two fulcrums are fixed and generates an electrostatic force between the first support and the first plate by an applied voltage is disposed at a position facing the first plate of the micromirror. The second electrode plate and the third electrode plate that generate an electrostatic force between the second flat plate and the applied voltage are moved from the first fulcrum to the second fulcrum at a position facing the second flat plate of the micromirror. A fourth electrode plate, which is arranged in parallel in the direction and generates an electrostatic force between the third plate and the applied voltage, is arranged at a position facing the third plate of the micromirror, and is mounted on the base substrate. Forming the substrate, the first fulcrum of the micromirror formed in the micromirror formation step, the first support of the substrate formed in the substrate formation step, and the micromirror formation step Bonding the second fulcrum of the micromirror formed in step 2 and the second support of the substrate formed in the substrate forming step, and bonding the micromirror to the substrate. It can be manufactured by the characteristic MEMS manufacturing method.

  In FIG. 12, the manufacturing process of MEMS902 in the manufacturing method which concerns on this invention 4th invention is shown. FIG. 12A shows the movable mirror array 121 formed in the micromirror forming process. The movable mirror array 121 has a plurality of micromirrors 101 arranged in parallel, and is manufactured from one silicon plate by an etching method or the like.

  FIG. 12B shows the substrate 402 formed in the substrate forming process. An integrated substrate 402 having the fourth electrode plate 54 from the first electrode plate 51 for each micromirror 101 is manufactured using a silicon plate or ceramics. Etching may be used for silicon plates, and ceramic green sheets having a multilayer structure may be baked and hardened for ceramics.

  FIG. 12C shows the joining process. The movable mirror array 121 and the substrate 402 are pasted up and down. For bonding, a solder bonding method or an anodic bonding method can be used. FIG. 12D shows the MEMS 902 after the bonding process. Although not shown, a metal frame with transparent glass (with AR coating) may be placed on the movable mirror array 121 to form a hermetically sealed micromirror module. In the hermetic sealing process, a solder bonding method, an anodic bonding method, or the like can be used as in the bonding process.

  As described above, the MEMS 902 can be manufactured by a simple method in which the movable mirror array 121 and the substrate 402 are separately prepared and then joined together. Therefore, according to the fourth invention of the present application, the MEMS 902 can be manufactured at low cost.

  The micromirror structure, the MEMS structure, and the MEMS manufacturing method according to the present invention can be applied to a wavelength selective switch using a dispersion element such as a bulk grating. By using this wavelength selective switch, light of an arbitrary wavelength can be freely switched between optical wavelength multiplexing metro rings without using conventional OEO (Optical-Electrical-Optical) conversion. In addition, the wavelength selective switch can be used as an RODAM (Reconfigurable Optical Add / Drop Multiplexer) that can extract or add an arbitrary wavelength by inserting it at an arbitrary position of the wavelength multiplexing ring.

It is a conceptual diagram of the micromirror 101 which concerns on one Embodiment of this invention 1st invention. 3 is a conceptual diagram of a spring hinge used for the first hinge 31 of the micromirror 101. FIG. 4 is a conceptual diagram of a spring hinge used for the second hinge 32 of the micro mirror 101. FIG. It is a conceptual diagram of MEMS901 which concerns on one Embodiment of this invention 2nd invention. 1 is a conceptual diagram of a substrate 401 included in a MEMS 901. FIG. It is the figure which showed the rotation state of the 2nd flat plate 22 of MEMS901. (A) is a perspective view, (b) is a side view from the direction (lateral direction) of the arrow of (a). It is the figure which showed the rotation state of the 2nd flat plate 22 of MEMS901. (A) is a perspective view, (b) is a side view from the direction (lateral direction) of the arrow of (a). It is the figure which showed the rotation state of the 2nd flat plate 22 of MEMS901. (A) is a perspective view, (b) is a side view from the direction (lateral direction) of the arrow of (a). It is the figure which showed the rotation state of the 2nd flat plate 22 of MEMS901. (A) is a perspective view, (b) is a side view from the direction (lateral direction) of the arrow of (a). It is the figure which showed the rotation state of the 2nd flat plate 22 of MEMS901. (A) is a perspective view, (b) is a side view from the direction (lateral direction) of the arrow of (a). It is a conceptual diagram of MEMS902 which concerns on embodiment of this invention 3rd invention. It is the figure which showed the process of the manufacturing method of MEMS which concerns on this invention 4th invention. (A) is the movable mirror array 121 after a micromirror formation process. (B) is the substrate 402 after the substrate formation step. (C) is a diagram showing a bonding process for bonding the movable mirror array 121 and the substrate 402. (D) is the MEMS 902 after the bonding step.

Explanation of symbols

101 Micromirror 121 Movable mirror array 401, 402 Substrate 901, 902 MEMS
21 1st flat plate 22 2nd flat plate 23 3rd flat plate 31 1st hinge 32 2nd hinge 33 3rd hinge 34 4th hinge 1A, 2A, 3A, 4A Connection point (theta) x, (theta) z Rotation direction 32a Spring hinge meanders in a horizontal direction The portion 32b where the spring hinge meanders in the vertical direction 41 The first support 42 The second support 51 The first electrode plate 52 The second electrode plate 53 The third electrode plate 54 The fourth electrode plates F14, F16, F18, F20 Static Electromotive force R15, R17, R19, R21 Rotational force

Claims (5)

A first flat plate arranged in order between the first fulcrum and the second fulcrum, a second flat plate and a third flat plate whose one surface is a mirror surface;
A first hinge that connects between the first fulcrum and the edge of the first flat plate and has a rotation axis in a direction parallel to the surface of the first flat plate and perpendicular to the direction of the second fulcrum from the first fulcrum When,
The edge of the first flat plate and the edge of the second flat plate on the opposite side of the first hinge are connected, and the direction parallel to the rotation axis of the first hinge is from one rotation axis and the first fulcrum. A second hinge having another rotational axis in a direction parallel to the direction of the second fulcrum;
The edge of the second flat plate opposite to the second hinge and the edge of the third flat plate are connected, and the direction parallel to the rotation axis of the first hinge is from one rotation axis and the first fulcrum. A third hinge having another rotation axis in a direction parallel to the direction of the second fulcrum;
A fourth hinge connecting the edge of the third flat plate opposite to the third hinge and the second fulcrum, and having a rotation axis in a direction parallel to the rotation axis of the first hinge;
A micromirror having a structure for rotating the second flat plate biaxially. The first hinge and the fourth hinge are
Having a spring hinge structure meandering in a direction parallel to the rotation axis of the first hinge;
The second hinge and the third hinge are
2. A spring hinge structure in which a portion meandering in a direction parallel to one rotation axis of the second hinge and a portion meandering in a direction parallel to another rotation axis of the second hinge are connected. Item 2. The micromirror according to Item 1. The micromirror according to claim 1 or 2,
A first support to which the first fulcrum of the micromirror is fixed and a second support to which the second fulcrum of the micromirror is fixed are mounted on the same surface, and the first support and the second support A substrate on which the micromirror is bridged with a support;
A MEMS comprising:
The substrate is
A first electrode plate that is disposed at a position facing the first flat plate on the surface on which the first support is mounted, and that generates an electrostatic force between the first flat plate and an applied voltage;
An electrostatic force is arranged between the first fulcrum and the second fulcrum in parallel with the second fulcrum at a position facing the second flat plate on the surface on which the first support is mounted. A second electrode plate and a third electrode plate for generating
A fourth electrode plate, which is disposed at a position facing the third flat plate on the surface on which the first support is mounted, and generates an electrostatic force between the third flat plate by an applied voltage;
Is further mounted, and the second flat plate is rotated biaxially by a voltage applied from the first electrode plate to the fourth electrode plate, and the mirror surface of the second flat plate is inclined at a desired angle. MEMS characterized by the above. The micromirror according to claim 1 or 2, wherein a plurality of the mirror surfaces of the second flat plate are arranged in parallel so as to be arranged in a plane.
A first support to which the first fulcrum of the micromirror is fixed and a second support to which the second fulcrum of the micromirror is fixed are mounted on the same surface, and the first support and the second support A substrate on which a plurality of the micromirrors are bridged with a support;
A MEMS comprising:
The substrate is for each micromirror,
A first electrode plate that is disposed at a position facing the first flat plate on the surface on which the first support is mounted, and that generates an electrostatic force between the first flat plate and an applied voltage;
An electrostatic force is arranged between the first fulcrum and the second fulcrum in parallel with the second fulcrum at a position facing the second flat plate on the surface on which the first support is mounted. A second electrode plate and a third electrode plate for generating
A fourth electrode plate, which is disposed at a position facing the third flat plate on the surface on which the first support is mounted, and generates an electrostatic force between the third flat plate by an applied voltage;
The second flat plate is rotated biaxially for each micromirror by a voltage applied from the first electrode plate to the fourth electrode plate for each micromirror, and the mirror surface of the second flat plate is A MEMS having a function of tilting to a desired angle. A micromirror forming step of forming the micromirror according to claim 1 or 2 from a silicon plate;
Forming a first support to which the first fulcrum of the micromirror is fixed and a second support to which the second fulcrum of the micromirror is fixed to a base substrate; A first electrode plate for generating an electrostatic force between the second plate and the second plate for generating an electrostatic force between the first plate and the second plate by an applied voltage. A three-electrode plate is arranged in parallel in the direction from the first fulcrum to the second fulcrum at a position facing the second flat plate of the micromirror, and an electrostatic force is generated between the third flat plate by an applied voltage. A substrate forming step of arranging a fourth electrode plate at a position facing the third flat plate of the micromirror, and forming a substrate from the base substrate;
The first fulcrum of the micromirror formed in the micromirror formation step and the first support of the substrate formed in the substrate formation step, and the micromirror formed in the micromirror formation step A joining step of combining the second fulcrum and the second support of the substrate formed in the substrate forming step, and bonding the micromirror to the substrate;
A MEMS manufacturing method comprising:

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