JP5612555B2 - Micromirror element and micromirror array - Google Patents

Description

  The present invention relates to a micromirror element and a micromirror array used for optical switching elements for communication, measuring instruments, displays, scanners, wavelength selective switches, and the like.

  In the field of optical networks that serve as the foundation of Internet communication networks, optical MEMS (Micro Electro Mechanical Systems) technology is in the spotlight as a technology that realizes multi-channel, wavelength division multiplexing (WDM), and cost reduction. An optical switch using optical MEMS technology has been developed (see Patent Document 1). The most characteristic component of the MEMS type optical switch is a micromirror array in which a plurality of micromirror elements are arranged.

  An optical switch enables path switching without converting light into an electrical signal. If an optical switch is used, even multiplexed light is demultiplexed for each wavelength. It is possible to switch the route without any problem. Such an optical switch is used, for example, to distribute a signal to another path when a failure occurs in the path being used and maintain a state where communication is possible.

  In recent years, wavelength selective switches that individually demultiplexed light for each wavelength after demultiplexing the multiplexed light for each wavelength have been researched and developed. Is used.

  Hereinafter, the micromirror element (micromirror array) disclosed in Patent Document 1 will be described with reference to FIG. Here, the micromirror element is composed of a mirror substrate and an electrode substrate disposed opposite thereto. The mirror substrate has a plurality of movable structures that act as mirrors, and a support member that rotatably supports the movable structures by a spring member such as a torsion spring. The electrode substrate is formed with a plurality of electrode portions corresponding to the movable structure acting as a mirror on the base substrate.

  FIG. 10 is a perspective view schematically showing the configuration of the mirror substrate and the electrode substrate. FIG. 10 partially shows a micromirror element, which is mainly one structural unit of the micromirror array. The micromirror array is one in which the micromirror elements shown in FIG. 10 are arranged one-dimensionally or two-dimensionally. The micromirror element includes a mirror substrate 1000 on which a mirror is formed and an electrode substrate 1300 on which an electrode is formed, and these are arranged in parallel.

  The mirror substrate 1000 includes a plate-shaped base 1010, a ring-shaped movable frame 1020, and a disk-shaped mirror 1030. The base 1010 includes an opening that is substantially circular in plan view. The movable frame 1020 is disposed in the opening of the base portion 1010 and is connected to the base portion 1010 by a pair of connecting portions 1011a and 1011b. The movable frame 1020 also has an opening that is substantially circular in plan view. The mirror 1030 is disposed in the opening of the movable frame 1020 and is coupled to the movable frame 1020 by a pair of mirror coupling portions 1021a and 1021b. In addition, a frame portion 1040 that surrounds the movable frame 1020 and the mirror 1030 is formed in the periphery of the base portion 1010. The frame portion 1040 is fixed to the base portion 1010 with an insulating layer 1050 interposed therebetween.

  The connecting portions 1011a and 1011b are provided in the cutouts of the movable frame 1020, are formed of torsion springs having a zigzag shape, and connect the base portion 1010 and the movable frame 1020. The movable frame 1020 connected to the base 1010 in this way is rotatable about a rotation axis (movable frame rotation axis) passing through the connection portions 1011a and 1011b. Further, the mirror connecting portions 1021a and 1021b are provided in the cutouts of the movable frame 1020, are constituted by torsion springs having a zigzag shape, and connect the movable frame 1020 and the mirror 1030. Thus, the mirror 1030 connected to the movable frame 1020 can be rotated around a rotation axis (mirror rotation axis) passing through the mirror connection portions 1021a and 1021b. The movable frame rotation axis and the mirror rotation axis are orthogonal to each other.

  On the other hand, the electrode substrate 1300 includes a plate-like base portion 1310, a protruding portion 1320 protruding from the upper surface of the base portion 1310, and a pair of protruding portions 1360a and a protruding portion arranged in parallel so as to sandwich the protruding portion 1320 around the protruding portion 1320. Part 1360b. The protrusion 1320 includes a second terrace 1322 having a truncated pyramid shape, a first terrace 1321 having a truncated pyramid shape formed on the upper surface of the second terrace 1322, and a pyramid formed on the upper surface of the first terrace 1321. And a pivot 1330 having a base shape. Pivot 1330 is arranged corresponding to the central portion of mirror 1030.

  Further, on the upper surface of the electrode substrate 1300 including the outer surface of the protruding portion 1320, fan-shaped electrodes 1340a, 1340b, 1340c, and 1340d are formed in a circle concentric with the mirror 1030 of the opposing mirror substrate 1000. . Furthermore, a wiring 1370 is formed inside the projections 1360a and 1360b around the protrusion 1320 of the electrode substrate 1300, and electrodes 1340a to 1340d are connected to the wiring 1370 via lead wires 1341a to 1341d. ing. These electrodes and wirings are formed on an insulating layer 1311 formed on the surface of the electrode substrate 1300.

  In the mirror substrate 1000 and the electrode substrate 1300 configured as described above, the corresponding mirror 1030 and the electrodes 1340a to 1340d are arranged to face each other, and the lower surface of the base portion 1010 is the upper surface of the convex portion 1360a and the convex portion 1360b of the base portion 1310. Are bonded via an insulating layer 1311 to form a micromirror element.

  In such a micromirror element, the mirror 1030 is grounded, a positive or negative voltage is applied between the electrodes 1340a to 1340d, and an asymmetric potential difference is generated between the electrodes 1340a to 1340d. The mirror 1030 can be rotated in an arbitrary direction by being attracted by electrostatic attraction.

  In addition, a wavelength selective switch for wavelength division multiplexing can be configured by using a micromirror array including the above-described micromirror elements. The configuration of this wavelength selective switch will be described with reference to FIG. FIG. 11 is a perspective view showing a configuration example of a 1-input n-output (m, n is an integer of 2 or more) branching wavelength selective switch for m wavelength division multiplexing WDM.

  This wavelength selective switch diffracts input light from one input side optical fiber 1101, n output side optical fibers 1102-1 to 1102-n, and an input port 1101a of the input side optical fiber 1101 to m. And a diffraction grating 1103 for demultiplexing an optical signal having a specific wavelength. In addition, m micro-waves that reflect the maximum m optical signals diffracted by the diffraction grating 1103 to the output ports 1102a-1 to 1102a-n of the corresponding output-side optical fibers 1102-1 to 1102-n for each wavelength. A micromirror array 1104 in which mirror elements 1104-1 to 1104-m are arranged is provided.

  In this wavelength selective switch, as shown in FIG. 11A, for example, a mirror 1104-1 of a micromirror element corresponding to an optical signal of an arbitrary wavelength is rotated around the x axis, and is diffracted and applied to the mirror. By reflecting the incident optical signal and coupling it to a predetermined output port, only an optical signal having a predetermined wavelength of the maximum m wavelength optical signal input from the input side optical fiber 1101 can be changed to an arbitrary output side optical fiber 1102. -1 to 1102-n.

  In addition, the optical signal diffracted in the direction orthogonal to the arrangement direction of the output side optical fibers 1102-1 to 1102-n is moved by rotating the mirror of the micromirror element about the y axis orthogonal to the x axis, By causing a so-called coupling shift, the power can be adjusted without the optical signal leaking into the other output side optical fiber. In this way, the wavelength selective switch not only outputs an optical signal of a specific wavelength from an arbitrary output port, but also adjusts the power of the optical signal to equalize the power of all optical signals of maximum m wavelengths. It also has a power equivalent function.

  In order to reduce the size of the micromirror array used in the wavelength selective switch as described above, it is necessary to arrange the micromirror elements at high density. As described above, when highly integrated, it is desirable that the ratio of the mirror width to the mirror pitch is 80% or more in order to ensure a sufficient transmission band of the optical signal. This ratio is called the fill factor. The fact that the fill factor is 80% or more means that, for example, when the mirror pitch is 100 μm, the mirror interval must be 20 μm or less. In recent years, the signal speed of optical signals has increased from 10 Gbps to 40 Gbps, and in the present situation where further increase in signal speed is expected in the future, it is desirable that the mirror interval be as small as possible.

  However, in the micromirror element configured as described above, since the mirror is disposed in the opening of the ring-shaped movable frame, the distance between the mirrors needs to be at least twice the width of the movable frame. For this reason, in order to make the space | interval of a mirror smaller, the width | variety of a movable frame will be made small. However, since the movable frame is also a structure that supports the mirror, a certain amount of width is necessary to ensure strength, and it is not easy to make it thin. For this reason, in the above-described micromirror element using a movable frame, it is difficult to realize a high fill factor, and it is difficult to secure a sufficient transmission band of an optical signal.

  As a technique for solving the above-described problem, a micromirror element has been proposed in which a movable electrode having a cantilever structure is used and the movable electrode is connected to both ends of a mirror via a connecting portion (see Patent Document 2). In this micromirror element, at least three movable electrodes (movable beams) having one end connected to the support portion are used, and two of these movable electrodes are connected to one end of the mirror via a spring member (connecting portion), and the rest The movable electrode is connected to the other end of the mirror via a spring member. In addition, a fixed electrode disposed opposite to the movable side of each movable electrode is provided, and the movable electrode is displaced by electrostatic attraction generated by voltage application to the fixed electrode. The mirror is rotated by the displacement of the movable electrode.

  In this micromirror element, a two-axis operation is possible with a first rotation axis in the arrangement direction of two sets of movable electrodes arranged opposite to each other with a mirror interposed therebetween, and a second rotation axis perpendicular thereto. Unlike the above-described micromirror element, this micromirror element does not require a frame portion to perform biaxial operation. Therefore, when a mirror array is used, a plurality of micromirror elements are compared with the above-described micromirror element. And can be arranged at narrower intervals.

JP 2003-057575 A JP 2009-229916 A JP 2010-096996 A

  However, the above-described micromirror element is long in this direction because the movable electrode is disposed at two locations facing each other across the mirror. For this reason, the area occupied by the micromirror array is increased, which hinders high integration of the micromirror array. In addition, the number of fixed electrodes arranged to face the movable side of each movable electrode is required, but as the number of micromirror arrays increases, the number of wires to these fixed electrodes increases. In addition, there is a concern about an increase in mounting cost and a decrease in reliability due to wire bonding or the like.

  The present invention has been made to solve the above-described problems, and is intended to be able to arrange more micromirror elements capable of two-axis operation in a smaller region and to reduce the mounting cost. Objective.

A micromirror element according to the present invention includes a mirror that is spaced apart on a substrate, a first support portion that supports one end of the mirror via one connection portion, and supports the mirror on the substrate, A second support portion sandwiched between the first support portion, a first movable beam having one end supported by the second support portion and the other end connected to the other end of the mirror via one connecting portion; A movable beam; a first drive electrode for displacing the other end of the first movable beam on the mirror side in a selected first direction away from the substrate and a direction approaching the substrate; and a mirror side of the second movable beam on the mirror side A second drive electrode for displacing the other end in the first direction, a first electric field separation electrode disposed opposite to the first drive electrode across the first movable beam, and a second drive across the second movable beam And at least a second electric field separation electrode disposed to face the electrode .

In the micromirror element, the first electric field separation electrode includes two side portions sandwiching a flat portion facing the flat surface of the first movable beam and a region obtained by extending the movable region of the first movable beam toward the first electric field separation electrode. The second electric field separation electrode is composed of a plane portion facing the plane of the second movable beam and two side portions sandwiching a region obtained by extending the movable region of the second movable beam toward the second electric field separation electrode. May be.

In the above SL micromirror device, the first driving electrode is composed of two sides sandwiching the movable area of the flat portion and the first movable beam facing the plane of the first movable beam, the second driving electrode, second You may make it comprise from the 2nd side part which pinches | interposes the movable part of the plane part and 2nd movable beam which oppose the plane of a movable beam.

  The micromirror array according to the present invention is a micromirror array in which a plurality of the above-described micromirror elements are arranged, and the plurality of micromirror elements are arranged in the arrangement direction of the first drive electrode and the second drive electrode, In the micromirror elements adjacent to each other in the arrangement direction, the first movable beam and the second movable beam are arranged on different sides.

  As described above, according to the present invention, since the mirror is operated by the two first movable beams and the second movable beam connected to the other end of the mirror, the micromirror element capable of two-axis operation is provided. It is possible to obtain an excellent effect that more can be arranged in a smaller area and the mounting cost can be reduced.

FIG. 1A is a plan view showing the configuration of the micromirror element according to Embodiment 1 of the present invention. FIG. 1B is a cross-sectional view showing the configuration of the micromirror element according to Embodiment 1 of the present invention. FIG. 1C is a perspective view showing a partial configuration of the micromirror element according to Embodiment 1 of the present invention. FIG. 2A is a plan view showing the configuration of the micromirror array according to Embodiment 1 of the present invention. FIG. 2b is a plan view showing the configuration of another micromirror array according to Embodiment 1 of the present invention. FIG. 3 is a plan view showing the configuration of the connecting portion 103. FIG. 4 is a perspective view showing the configuration of the micromirror element according to Embodiment 2 of the present invention. FIG. 5 is a cross-sectional view showing a partial configuration of the micromirror element according to the second embodiment of the present invention. FIG. 6 is a plan view showing a partial configuration of the micromirror element according to the second embodiment of the present invention. FIG. 7 is an explanatory diagram for explaining the operation of the micromirror element according to the second embodiment of the present invention. FIG. 8 is a characteristic diagram showing the relationship between the drive voltage V and the rotation (rotation) angle θ of the mirror. FIG. 9 is a characteristic diagram showing the relationship between the rotation angle of the mirror and dθ / dV. FIG. 10 is a perspective view showing a configuration of a conventional micromirror element. FIG. 11 is a perspective view showing a configuration of a demultiplexing type wavelength selective switch using a mirror.

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

[Embodiment 1]
First, Embodiment 1 of the present invention will be described. FIG. 1A is a plan view showing the configuration of the micromirror element according to Embodiment 1 of the present invention. FIG. 1B is a cross-sectional view showing the configuration of the micromirror element according to Embodiment 1 of the present invention. FIG. 1C is a perspective view showing a partial configuration of the micromirror element according to Embodiment 1 of the present invention.

  The micromirror element includes a mirror 102 disposed on a substrate 101 so as to be spaced apart from each other, a first support portion 104 that supports one end of the mirror 102 via one connection portion 103 and supports the substrate 102 on the substrate 101. The second support part 105 facing the first support part 104 with the mirror 102 interposed therebetween, one end supported by the second support part 105 and the other end having one connecting part 106a, 106b at the other end of the mirror 102, respectively. The first movable beam 107 and the second movable beam 108 are connected to each other.

  The micromirror element also includes a first drive electrode 109 for displacing the other end of the first movable beam 107 on the mirror 102 side in a selected first direction away from the substrate 101 and in a direction approaching the substrate 101. And the second drive electrode 110 for displacing the other end of the second movable beam 108 on the mirror 102 side in the first direction. In FIG. 1A and FIG. 1B, the first direction is a direction approaching the substrate 101. For example, the first support part 104 and the second support part 105 are formed on the substrate 101 via an insulating layer 121. For example, the first drive electrode 109 is connected to a wiring 122 formed on the substrate 101 below the insulating layer 121 via a contact wiring 123 that penetrates the insulating layer 121. In addition, in a region (not shown) of the substrate 101, a drive circuit that generates a drive signal for the above-described displacement is formed.

  The micromirror element according to the first embodiment described above includes the electrode substrate on which the first drive electrode 109 and the second drive electrode 110 are formed, the connecting portion 103, the mirror 102, the connecting portion 106a, the connecting portion 106b, and the first movable beam 107. The mirror substrate on which the second movable beam 108 and the like are formed is bonded to the support substrate through a support structure.

  The mirror substrate may be formed from, for example, an SOI (Silicon On Insulator) substrate. The SOI substrate is provided with a thin silicon layer (SOI layer) on a thick base portion made of silicon via a buried insulating layer. By processing the SOI layer, the connecting portion 103, the mirror 102, and the connecting portion are provided. A plate-like structure such as 106a, connecting portion 106b, first movable beam 107, and second movable beam 108 may be formed. At this time, a peripheral portion connected to the connecting portion 103 and a peripheral portion connected to the first movable beam 107 and the second movable beam 108 are simultaneously formed. After processing these structures, the base portion, the buried insulating layer, and the like may be removed. The reflective film formed on the mirror 102 may be formed by depositing a desired metal by, for example, sputtering or vapor deposition.

  On the other hand, the electrode substrate can be formed by using a well-known method for manufacturing a semiconductor device such as an LSI integrated circuit. In addition, a single crystal silicon substrate having a (100) crystal orientation of the main surface is etched with an alkaline solution such as potassium hydroxide to form a recess having a predetermined depth in the silicon substrate, thereby forming a support structure. An electrode substrate may be formed. As is well known, single crystal silicon has a significantly lower etching rate for alkali on the (111) plane than on the (100) plane or the (110) plane. A support structure can be formed by utilizing this phenomenon. What is necessary is just to affix the peripheral part connected to the connection part 103, and the peripheral part connected to the 1st movable beam 107 and the 2nd movable beam 108 to each support structure of the electrode substrate formed in this way.

  In addition, you may make it use the support structure prepared separately. For example, a support structure formed by solder bumps or plating may be used. Moreover, the manufacturing method which laminates | stacks a mirror part and an electrode part by surface micromachining and forms integrally may be sufficient.

  Hereinafter, the rotation operation of the mirror 102 in the micromirror element according to the present embodiment will be described. In the following, it is assumed that a reflecting surface is formed on the mirror 102 on the surface opposite to the substrate 101 side. In this micromirror element, first, a drive voltage is applied to both the first drive electrode 109 and the second drive electrode 110, and the first movable beam 107 and the second movable beam 108 are displaced in the first direction, whereby a mirror is obtained. The reflecting surface 102 can be oriented in the negative direction of the y-axis. This means that the mirror 102 is rotated around the rotation axis in the x-axis direction in the figure.

  Further, for example, by applying a drive voltage only to the first drive electrode 109 and displacing only the first movable beam 107 in the first direction, the reflecting surface of the mirror 102 can be directed in the + direction of the x axis. . Note that the same applies when a driving voltage larger than that of the second driving electrode 110 is applied to the first driving electrode 109. Further, if the application state of the drive voltage is switched between the first drive electrode 109 and the second drive electrode 110, the reflection surface of the mirror 102 can be directed in the negative direction of the x axis. As described above, according to the micromirror element of the first embodiment, the mirror 102 can be biaxially operated by the two first movable beams 107 and the second movable beams 108 provided on one end side of the mirror 102. .

  According to the first embodiment described above, the mirror 102 includes two movable beams on one side and no movable beam on the other side. Therefore, the mirror 102 in the y-axis direction in FIGS. 1A, 1B, and 1C and The length of the movable beams in the arrangement direction can be shortened compared to the case where movable beams are provided at both ends. As a result, according to the present embodiment, more micromirror elements capable of two-axis operation can be arranged in a narrower region. In addition, since the number of fixed electrodes (drive electrodes) is as small as two, even if the number of micromirror arrays is increased, the number of wires to these fixed electrodes can be reduced, and the mounting cost by wire bonding can be reduced. The reliability of the mirror element is also maintained.

  Note that the micromirror elements may be arranged as shown in the plan view of FIG. 2A to form a micromirror array. As shown in FIG. 2A, a plurality of micromirror elements are arranged inside the integrally formed frame portion 113. Two opposing side portions of the frame portion 113 are referred to as a first support portion 104 and a second support portion 105 of the micromirror element, respectively.

  Here, the connection part 103 and the connection parts 106a and 106b will be described. Hereinafter, the connecting portion 103 will be described as a representative. Further, the direction connecting one connecting point and the other connecting point connected by the connecting portion 103 is the “y-axis direction”, and the width direction of the connecting portion 103, that is, in the plane including the connecting portion 103, is orthogonal to the y-axis direction. The direction is “x-axis direction”.

  The connecting portion 103 has a substantially rectangular shape in cross section orthogonal to the x-axis direction or the y-axis direction, and has a substantially H-shaped planar shape in which a substantially square shape is formed symmetrically with respect to the y-axis, as shown in FIG. Have. The connecting portion 103 includes 15 parts 131a, 132a, 133a, 134a, 135a, 136a, 137a, 138, 131b, 132b, 133b, 134b, 135b, 136b, And the portion 131a is connected to the mirror 102, the portion 131b is connected to the first support portion 104, and the mirror 102 is rotatably connected to the first support portion 104.

  In addition, the connection part 103 of this invention is not limited to the substantially H-shaped shape shown in FIG. A linear torsion spring may be used in the y-axis direction, and it may have a zigzag shape in the x-axis direction.

  In the plan view of FIG. 2A, the micromirror elements are arranged uniformly to form a micromirror array. However, the movable beams of adjacent mirror elements may be arranged on different sides. For example, as shown in FIG. 2B, the first support portion 104 side and the second support portion 105 side to which the connecting portions 103 of the adjacent micromirror elements and the first movable beam 107 and the second movable beam 108 are connected are mutually connected. Arrange them differently. However, the centers of the micromirrors 102 are arranged so as to be arranged on the same straight line. By arranging in this way, the first movable beam 107 and the second movable beam 108 are not affected by the electrostatic force from the first drive electrode 109 and the second drive electrode 110 of the adjacent micromirror elements. Controllability of the rotation angle of the mirror is improved. That is, the influence of crosstalk between adjacent elements can be further suppressed.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. FIG. 4 is a perspective view showing the configuration of the micromirror element according to Embodiment 2 of the present invention. The micromirror element includes a mirror 402 that is spaced apart on a substrate (not shown), and a first support unit that supports one end of the mirror 402 via one connection unit 403 and supports the substrate on the substrate. (Not shown) and a second support portion (not shown) facing the first support portion with the mirror 402 interposed therebetween. Although the substrate, the first support portion, and the second support portion are not shown, they are the same as those in the first embodiment.

  In addition, the micromirror element has two first movable beams 407 and one second supported by one end supported by the second support portion and the other end connected to the other end of the mirror 402 via one connection portion 406a and 406b, respectively. A movable beam 408 is provided. Also, a first drive electrode 409 for displacing the other end of the first movable beam 407 on the mirror 402 side in a first direction selected from the direction away from the substrate and the direction approaching the substrate, and the mirror of the second movable beam 408 And a second drive electrode 410 for displacing the other end on the 402 side in the first direction. Also in this embodiment, the direction approaching the substrate is the first direction. In the present embodiment, a plurality of micromirror elements can be arranged to form a micromirror array, as in the first embodiment.

  Further, in the present embodiment, as shown in the cross-sectional view of FIG. 5, the first drive electrode 409 sandwiches the plane portion 409 a facing the plane of the first movable beam 407 and the movable region of the first movable beam 407. The second drive electrode 410 is composed of two side portions 410b that sandwich the movable region of the second movable beam 408 and the flat portion 410a facing the plane of the second movable beam 408. Here, in the present embodiment, the plane portion and the side portion are integrally formed. What is necessary is just to form the metal of a 1st drive electrode or a 2nd drive electrode by depositing by the plating method, a sputtering method, a vapor deposition method etc., for example. 5 is a cross-sectional view showing a cross section of the xz plane in the drive electrode formation region of FIG.

  Thus, by providing a side portion on each drive electrode, when a plurality of micromirror elements are arranged, the electric field for driving the movable beam can be separated for each micromirror element. By including the side portion, the electric lines of force from the plane portion to the movable beam adjacent thereto are almost shielded, and the influence of crosstalk can be suppressed. Such suppression of crosstalk is most effective when the height of the side portion is approximately the same as the position in the height direction of the movable beam in the initial state.

  In addition, the micromirror element according to the present embodiment includes a first electric field separation electrode 411 disposed opposite to the first drive electrode 409 with the first movable beam 407 interposed therebetween, and a second drive electrode with the second movable beam 408 interposed therebetween. 410 and a second electric field separation electrode 412 arranged to face each other. Each electric field separation electrode may be grounded, or may have the same potential as the first movable beam 407, the second movable beam 408, and the mirror 402. By providing the electric field separation electrode, when a plurality of micromirror elements are arranged, the leakage electric field from the drive electrode in the direction of the movable beam can be shielded for each micromirror element. Thereby, the influence of crosstalk between adjacent elements can be further suppressed.

  Further, in the present embodiment, as shown in the cross-sectional view of FIG. 5, the first electric field separation electrode 411 includes the flat portion 411 a facing the plane of the first movable beam 407 and the movable region of the first movable beam 407. The first electric field separation electrode 411 includes two side portions 411b sandwiching a region extending toward the electric field separation electrode 411, and the second electric field separation electrode 412 includes a flat portion 412a and a second movable beam 408 facing the plane of the second movable beam 408. The movable region is composed of two side portions 412b sandwiching a region extending to the second electric field separation electrode 412 side. In the present embodiment, the planar portion and the side portion are integrally formed in the present embodiment. A substrate formed by depositing the metal of the first electric field separation electrode 411 and the second electric field separation electrode 412 by, for example, plating, sputtering, vapor deposition or the like may be bonded to the mirror substrate. By doing in this way, the electric field which leaks to the movable beam side seeing from the drive electrode can be shielded more efficiently.

  Hereinafter, the rotation operation of the mirror 402 in the micromirror element according to the present embodiment will be described. Hereinafter, as shown in the plan view of FIG. 6, the first movable beam 407, the second movable beam 408, and the mirror 402 are orthogonal to the direction in which the mirror 402 is arranged and parallel to the plane of the substrate (not shown). An axis passing through the connecting part 403 is a main axis 601, and an axis parallel to the plane of the substrate and orthogonal to the main axis 601 is a sub axis 602. The main shaft 601 is parallel to the x axis, and the sub shaft 602 is parallel to the y axis. Further, it is assumed that a reflection surface is formed on the mirror 402 on the surface opposite to the substrate side. The drive voltage applied to the first drive electrode 409 is V1, and the drive voltage applied to the second drive electrode 410 is V2.

  First, by setting V1 = V2, if the first movable beam 407 and the second movable beam 408 are displaced to the substrate side (first direction), the reflecting surface of the mirror 402 is directed in the negative direction of the y-axis. Can do. This means that the mirror 402 is rotated by the main shaft 601.

Further, by setting V1 <V2, the second movable beam 408 is displaced in the first direction with respect to the first movable beam 407, and as shown in the perspective view of FIG. 701 can be oriented in the negative direction of the x-axis. This means that the mirror 402 is rotated by the auxiliary shaft 602. If V1> V2, the reflecting surface 701 of the mirror 402 can be directed in the + direction of the x axis. Thus, also in the micromirror element according to the second embodiment, the mirror 402 can be biaxially operated by the two first movable beams 407 and the second movable beams 408 provided on one end side of the mirror 402.

  Here, the length of the mirror 402 in the y-axis direction (mirror length) is 600 μm, the length of the mirror 402 in the x-axis direction (mirror width) is 200 μm, and the first movable beam 407 and the second movable beam 408 are A simulation result of the mirror operation when the arrangement interval is 108 μm will be described with reference to FIGS. 8 and 9. FIG. 8 shows the relationship between the drive voltage V and the rotation (rotation) angle θ of the mirror, and FIG. 9 shows the relationship between the rotation angle and dθ / dV. 8 and 9, (a) shows a change when the same drive voltage is applied to the two drive electrodes and the mirror is rotated about the main axis. Further, (b) shows a change when different drive voltages are applied to the two drive voltages and the mirror is rotated about the secondary axis. In this secondary shaft rotation operation, the difference between the voltages applied to the two drive electrodes is used as the drive voltage.

  As is clear from FIGS. 8 and 9, a larger rotation angle is obtained in the counter shaft rotation operation than in the main shaft rotation operation. For example, as shown in FIG. 8, when the driving voltage is 180 V, the rotation angle is 2.3 deg. However, in the secondary shaft rotation operation, 6.3 deg. Of rotation is obtained.

  According to the second embodiment described above, one of the mirrors 402 is provided with two movable beams and the other is not provided with a movable beam. Therefore, the arrangement of the mirror 402 and the movable beams in the y direction in FIG. The length in the direction can be shortened compared to the case where movable beams are provided at both ends. As a result, according to the present embodiment, more micromirror elements capable of two-axis operation can be arranged in a narrower region. In addition, since the number of fixed electrodes is small, even if the number of micromirror arrays is increased, the number of wires to these fixed electrodes can be reduced, and the mounting cost by wire bonding can be reduced. Sex is also maintained.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious. For example, in the above-described embodiment, since the fixed electrode facing the mirror is not provided, the planar shape of the mirror is rectangular, but the present invention is not limited to this.

  In the above-described embodiment, the drive electrode is disposed on the substrate side, but the present invention is not limited to this. A drive electrode may be arranged above the movable beam as viewed from the substrate so that the movable beam is displaced in a direction away from the substrate. Moreover, a connection part is not restricted to a substantially H shape, For example, you may have a zigzag folding shape.

  DESCRIPTION OF SYMBOLS 101 ... Board | substrate, 102 ... Mirror, 103 ... Connection part, 104 ... 1st support part, 105 ... 2nd support part, 106a, 106b ... Connection part, 107 ... 1st movable beam, 108 ... 2nd movable beam, 109 ... 1st drive electrode, 110 ... 2nd drive electrode, 121 ... insulating layer, 122 ... wiring, 123 ... contact wiring.

Claims (4)

A mirror spaced apart on the substrate;
A first support part that supports one end of the mirror via one connection part and supports the mirror on the substrate;
A second support portion facing the first support portion with the mirror interposed therebetween;
A first movable beam and a second movable beam, one end of which is supported by the second support portion and the other end of which is connected to the other end of the mirror via one connecting portion;
A first drive electrode for displacing the other end of the first movable beam on the mirror side in a selected first direction away from the substrate and in a direction approaching the substrate;
A second drive electrode for displacing the other end of the second movable beam on the mirror side in the first direction;
A first electric field separation electrode disposed opposite to the first drive electrode across the first movable beam;
A micromirror element comprising: at least a second electric field separation electrode disposed opposite to the second drive electrode with the second movable beam interposed therebetween. The micromirror element according to claim 1, wherein
The first electric field separation electrode is composed of a flat portion facing the flat surface of the first movable beam and two side portions sandwiching a region obtained by extending the movable region of the first movable beam toward the first electric field separation electrode. And
The second electric field separation electrode is composed of a flat portion facing the flat surface of the second movable beam and two side portions sandwiching a region obtained by extending the movable region of the second movable beam toward the second electric field separation electrode. The micromirror element characterized by the above-mentioned. The micromirror element according to claim 1 or 2 ,
The first drive electrode is composed of a plane portion facing the plane of the first movable beam and two side portions sandwiching the movable region of the first movable beam,
The micro-mirror element, wherein the second drive electrode is composed of a plane part facing the plane of the second movable beam and two side parts sandwiching a movable region of the second movable beam. A micromirror array in which a plurality of the micromirror elements according to any one of claims 1 to 3 are arranged,
A plurality of the micromirror elements are arranged in an arrangement direction of the first drive electrode and the second drive electrode,
The micromirror array, wherein the micromirror elements adjacent to each other in the arrangement direction are arranged on different sides of the first movable beam and the second movable beam.