JP2015175914A - Micromirror element and mirror array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micromirror element and micromirror array that can attain miniaturization.SOLUTION: A mirror substrate 10 has: an opening part 11; a pair of support members 12; a pair of movable beams 13-1 and 13-2 that is formed in the opening part 11, and has one end fixed to the support member 12 and has other end made capable of displacement; a mirror 14 that is connected to the other end of the movable beam; and spring members 15-1 and 15-2 that link the movable beam 13 and mirror 14. In an electrode substrate 20, plane view substantially rectangular stationary electrodes 21-1 and 21-2 are formed at a position facing the movable beams 13-1 and 13-2. Herein, in the movable beams 13-1 and 13-2, three openings 13a to 13c are formed along an extending direction. Further, the stationary electrodes 21-1 and 21-2 have protrusion parts 21a to 21c that protrude toward three openings 13a to 13c of the movable beams 13-1 and 13-2 oppositely arranged.

Description

  The present invention relates to a micromirror element and a mirror array.

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

An optical switch performs path switching without converting an optical signal into an electrical signal, and even a multiplexed optical signal can be switched without being demultiplexed for each wavelength. is there. Such an optical switch is used, for example, in order to maintain a communicable state by distributing a signal to another route when a failure occurs in the route being used.
In recent years, a wavelength selective switch has been developed that individually demultiplexes the multiplexed light for each wavelength and then individually selects the light path of each wavelength. A micromirror element is also used here. ing. Furthermore, a mirror array using a mirror element that enables a plurality of mirrors to be arranged closer to each other has also been proposed (see, for example, Patent Document 2 and Non-Patent Document 1). An example of such a mirror array will be described with reference to FIGS.

  The mirror array has a structure in which a shield cap 300 is fitted into a mirror substrate 100, an electrode substrate 200 disposed opposite to the mirror substrate 100, and a rectangular opening 101 formed in the mirror substrate 100 in plan view. ing.

  The mirror substrate 100 includes a support portion 102, movable beams 103 a and 103 b that are movable electrodes formed in the opening 101, a mirror 104, and support springs 105 a that serve as connecting portions between the movable beams 103 a and 103 b and the mirror 104. 105b. One end of the movable beams 103 a and 103 b is fixed to the support portion 102. Thereby, each of the movable beam 103a and the movable beam 103b has a cantilever structure in which each other end can be displaced in the normal direction (z-axis direction) of the mirror substrate.

  A mirror 104 is disposed between the movable beam 103a and the movable beam 103b by being connected by a pair of bending support springs 105a and 105b. The mirror 104 is arranged in a row with the movable beam 103a and the movable beam 103b, and is disposed so as to be rotatable between the movable beam 103a and the movable beam 103b. The support spring 105a connects the other end of the movable beam 103a and the mirror 104, and the support spring 105b connects the other end of the movable beam 103b and the mirror 104. 22 to 23, the movable beam 103a, the support spring 105a, the mirror 104, the support spring 105b, and the movable beam 103b are sequentially aligned on a line parallel to the y-axis direction.

  The mirror 104 passes through the pair of support springs 105a and 105b, and can rotate about a first rotation axis parallel to the y-axis, and a first mirror parallel to the x-axis orthogonal to the length direction of the mirror 104. It is possible to rotate around 2 rotation axes. A reflective film made of gold or aluminum is formed on the surface of the mirror 104 so that, for example, light in the infrared region can be reflected. The alignment of the movable beam 103a, the support spring 105a, the mirror 104, the support spring 105b, and the movable beam 103b as described above forms a structure on the mirror substrate side of one micromirror element. A plurality of elements are arranged along the vertical x-axis direction to form a structure on the mirror substrate side of the mirror array chip.

  On the other hand, on each electrode substrate 200, fixed electrodes 201a and 201b for driving the movable beams 103a and 103b and mirror drive electrodes 202a and 202b for driving the mirror 104 are provided for each micromirror element. Is provided. A shield wall 203 is formed between the mirror drive electrodes 202a and 202b for driving one mirror 104 and the mirror drive electrodes 202a and 202b for driving the adjacent mirror 104. Further, a gap control bump 204 is formed on the electrode substrate 200 to fix the mirror substrate 100 at a predetermined distance. Further, in the electrode substrate 200, wiring 205 connected to the fixed electrodes 201a and 201b and wiring 206 connected to the mirror drive electrodes 202a and 202b are formed.

  When the mirror substrate 100 and the electrode substrate 200 are joined, the fixed electrodes 201a and 201b are arranged to face the movable beams 103a and 103b, respectively, and the mirror drive electrodes 202a and 202b are made to face the mirror 104. Has been placed. The fixed electrodes 201a and 201b have a substantially U-shaped cross section in which grooves are formed along a direction parallel to the y-axis, that is, a direction parallel to the alignment direction of the movable beams 103a and 103b.

  A driving voltage (drive signal) for driving the movable beam 103a and the movable beam 103b is supplied to the fixed electrodes 201a and 201b via the wiring 205, respectively. Further, a mirror driving voltage is supplied to the mirror driving electrodes 202 a and 202 b through the wiring 206. The movable beams 103a and 103b, the mirror 104, and the support springs 105a and 105b are set to the same potential by grounding or the like.

  In the shield cap 300, a groove 301 extending along the y-axis direction is formed on the lower surface in the x-axis direction. Such a shield cap 300 is disposed so that each groove 301 faces the corresponding movable beams 103a and 103b when bonded to the mirror substrate 100.

  The operation of one micromirror element in such a mirror array will be described with reference to FIGS.

  First, when a predetermined drive voltage is applied to the fixed electrodes 201a and 201b, the movable beams 103a and 103b bend with one end supported by the support portion 102 as a fulcrum by the generated electrostatic attraction, and the movable beams 103a and 103b The other end side is displaced so as to be attracted to the electrode substrate 200. As a result, the mirror 104 is pulled toward the electrode substrate 200 and is tilted. This tilted state means that the mirror is rotating around a rotation axis (main axis) passing through the center of the mirror parallel to the arrangement direction (x axis) of the mirrors 104. Since the micromirror element has a symmetric structure with respect to the main axis, the mirror 104 can be rotated in both positive and negative directions around the main axis by controlling the drive voltage applied to the fixed electrodes 201a and 201b. it can.

  Further, when a predetermined drive voltage is applied to the two mirror drive electrodes 202a and 202b arranged immediately below the mirror 104, the mirror 104 is parallel to the y axis passing through the pair of support springs 105a and 105b due to the generated electrostatic attraction. It rotates around a rotating shaft (sub shaft). Since the micromirror element has a symmetric structure with respect to the secondary axis, the mirror 104 is rotated in both positive and negative directions around the secondary axis by controlling the drive voltage applied to the mirror drive electrodes 202a and 202b. Can be moved.

  In such a micromirror array in which micromirror elements are arranged at a narrow interval, when a movable beam is driven, an electric field due to a fixed electrode of an adjacent micromirror element may interfere. Then, the movable beam moved and the rotation angle of the mirror sometimes fluctuated. In order to prevent such mirror fluctuations, it is necessary to reduce the interference of the electric field of adjacent micromirror elements. To this end, an electrode structure that completely separates the electric field for each movable beam should be realized. Is effective. Therefore, as shown in FIG. 26, the fixed electrodes 201a and 201b have a substantially U-shaped cross section so that the electric field surrounds the movable beam. Further, a shield cap 300 is disposed above the mirror 104. As a result, the electric field is separated for each movable beam to reduce interference.

JP 2003-057575 A International Publication No. 2008/129988

M. Usui et al., “Electrically Separated Two-Axis MEMS Mirror Array Module for Wavelength Selective Switches,” 2009 IEEE / LEOS International Conf. On Optical MEMS and Nanophotonics, ThB4, Clearwater Beach, FL USA, 2009.

  However, in a micromirror array in which micromirror elements using fixed electrodes having a substantially U-shaped cross section are arranged, the fixed electrodes of adjacent micromirror elements are also close to each other, so that insulation between the fixed electrodes is secured. The fixed electrodes need to be spaced apart from each other by a predetermined distance. For this reason, the interval between adjacent micromirror elements cannot be reduced, and as a result, it is difficult to reduce the size of the micromirror array.

  Accordingly, an object of the present invention is to provide a micromirror element and a micromirror array that can be miniaturized.

  In order to solve the above-described problems, a micromirror element according to the present invention includes a support member, a movable beam having one end fixed to the support member and the other end being displaceable, and the movable beam described above. A reflection portion having a mirror connected to the other end via a spring member; and a fixed electrode disposed on the surface spaced from the reflection portion so as to face the movable beam, the movable beam having an opening The fixed electrode has a protruding portion protruding toward the opening.

  In the micromirror element, the movable beam has a plurality of openings along an extending direction, and the fixed electrode has a plurality of protrusions protruding toward the plurality of openings. Good.

  The micromirror element may include a plurality of the movable beams arranged to face each other with the mirror interposed therebetween, and a plurality of the fixed electrodes facing each of the plurality of movable beams.

  The micromirror element may include a plurality of the movable beams arranged in parallel to each other and a plurality of the fixed electrodes arranged in parallel to each other.

  The micromirror element may further include a wall-like member that is provided between two adjacent fixed electrodes that are arranged in parallel to each other and that is made of a conductor.

  The mirror array according to the present invention is characterized in that a plurality of the above-described micromirror elements are arranged so that the movable beams are arranged in an array.

  The micromirror array may further include a flat plate-like member disposed above the movable beam.

  The micromirror array may further include the wall-like member that is provided between the fixed electrodes of the adjacent micromirror elements and is made of a conductor.

  According to the present invention, since the movable beam has an opening and the fixed electrode has a protruding portion that protrudes toward the opening, it is possible to reduce the interference of the electric field between the fixed electrodes of adjacent micromirror elements. Therefore, the distance between adjacent fixed electrodes can be shortened, and as a result, downsizing can be realized.

FIG. 1 is a plan view showing the configuration of the micromirror element according to the first embodiment of the present invention. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a plan view showing the configuration of the spring member. FIG. 4 is a diagram for explaining the operation of the micromirror element according to the first embodiment of the present invention. FIG. 5 is a diagram for explaining the operation of the micromirror element according to the first embodiment of the present invention. FIG. 6 is a plan view showing the configuration of the micromirror array according to the first embodiment of the present invention. 7 is a cross-sectional view taken along line II-II in FIG. FIG. 8 is a diagram for explaining the electric field shielding effect in the micromirror array. FIG. 9 is a diagram for explaining the electric field shielding effect in the micromirror array. FIG. 10 is a plan view showing the configuration of the micromirror element according to the second embodiment of the present invention. 11 is a cross-sectional view taken along line III-III in FIG. FIG. 12 is a diagram for explaining the operation in the micromirror element according to the second embodiment of the present invention. FIG. 13 is a diagram for explaining the operation in the micromirror element according to the second embodiment of the present invention. FIG. 14 is a plan view showing the configuration of the micromirror array according to the second embodiment of the present invention. 15 is a cross-sectional view taken along line IV-IV in FIG. FIG. 16 is a plan view showing the configuration of the micromirror element according to the third embodiment of the present invention. 17 is a cross-sectional view taken along line VV in FIG. FIG. 18 is a diagram for explaining the operation in the micromirror element according to the third embodiment of the present invention. FIG. 19 is a diagram for explaining an operation in the micromirror element according to the third embodiment of the present invention. FIG. 20 is a plan view showing the configuration of the micromirror array according to the third embodiment of the present invention. 21 is a cross-sectional view taken along line VI-VI in FIG. FIG. 22 is a perspective view schematically showing a configuration of a conventional micromirror array. FIG. 23 is a cross-sectional view of a conventional micromirror array. FIG. 24 is a diagram for explaining the operation of a conventional micromirror array. FIG. 25 is a diagram for explaining the operation of the conventional micromirror array. FIG. 26 is a diagram for explaining the electric field shielding effect in the conventional micromirror array.

[First Embodiment]
First, a first embodiment of the present invention will be described in detail with reference to the drawings.

<Configuration of micromirror element>
As shown in FIGS. 1 and 2, the micromirror element 1 according to the present embodiment includes a mirror substrate 10 and an electrode substrate 20 disposed to face the mirror substrate 10.

The mirror substrate 10 is formed in the opening 11 with a substantially rectangular opening 11 in a plan view, a pair of support members 12 positioned on a pair of opposite sides of the opening 11 and arranged in parallel to each other, and supported in the opening 11. A pair of movable beams 13-1 and 13-2 having one end fixed to the member 12 and the other end being displaceable, a mirror 14 connected to the other end of the movable beam, the movable beam 13 and the mirror 14, Are provided with spring members 15-1 and 15-2.
In the following, the direction along the extending direction of the support member 12 is the x-axis direction, the direction perpendicular to the x-axis direction and the direction along the plane direction of the mirror substrate 10 is the y-axis direction, and the mirror substrate 10 and The distance direction of the electrode substrate 20 is the z-axis direction.

The movable beams 13-1 and 13-2 are formed in a substantially rectangular plate shape in plan view, the longitudinal direction is along the y-axis direction, one short side (fixed end) is fixed to the support member 12, and the other short side Spring members 15-1 and 15-2 corresponding to the sides (movable ends) are connected and arranged to face each other with the mirror 14 interposed therebetween.
In addition, three openings 13a to 13c are formed in the movable beams 13-1 and 13-2 along the extending direction. In the present embodiment, the openings 13a to 13c are formed between the substantially central portions of the movable beams 13-1 and 13-2 and the movable ends.

  The mirror 14 is formed in a plate shape having a rectangular shape in plan view, and corresponding spring members 15-1 and 15-2 are connected to the central part of a pair of opposite sides.

  As shown in FIG. 3, the spring members 15-1 and 15-2 are formed in a substantially H shape in plan view.

  On the other hand, fixed electrodes 21-1 and 21-2 having a substantially rectangular shape in plan view are formed on the electrode substrate 20 at positions facing the movable beams 13-1 and 13-2. Further, mirror drive electrodes 22-1 and 22-2 are formed at positions facing the mirror 14 of the electrode substrate 20. On the electrode substrate 20, gap control bumps 23 protruding in the z-axis direction are formed in order to fix the mirror substrate 10 at a predetermined distance. Further, in the electrode substrate 20, wirings 24 connected to the fixed electrodes 21-1 and 21-2 and wirings 25 connected to the mirror driving electrodes 22-1 and 22-2 are formed.

Here, the fixed electrodes 21-1 and 21-2 have projecting portions 21 a to 21 c that project toward the three openings 13 a to 13 c of the movable beams 13-1 and 13-2 arranged to face each other.
The outer shapes of the protrusions 21a to 21c are smaller than the outer shapes of the openings 13a to 13c in the planar direction of the electrode substrate 20, and are located inside the openings 13a to 13c when the electrode substrate 20 is viewed from the mirror substrate 10 side. It is formed as follows. Accordingly, when the movable beams 13-1 and 13-2 move toward the electrode substrate 20, the projecting portions 21a to 21c are located in the openings 13a to 13c, so that the projecting portions 21a to 21c are moved to the movable beams 13-1, 13c. Do not touch 13-2.
The height of the projecting portions 21a to 21c in the z-axis direction can be arbitrarily set as long as it is a position separated from the movable beams 13-1 and 13-2.

  The mirror drive electrodes 22-1 and 22-2 are formed in a substantially rectangular shape in plan view, and are arranged in parallel in the x-axis direction.

  The fixed electrodes 21-1 and 21-2 and the mirror drive electrodes 22-1 and 22-2 are applied with independently controlled voltages (hereinafter referred to as drive voltages) from the outside via the wiring 24 or the wiring 25. As a result, the movable beams 13-1, 13-2 or the mirror 14 arranged to face each other are driven by electrostatic attraction.

<Operation of micromirror element>
Next, the operation of the micromirror element 1 according to the present embodiment will be described with reference to FIGS.

  First, when a driving voltage is applied to either one of the fixed electrodes 21-1 and 21-2, the movable beams 13-1 and 13-2 disposed to face the fixed electrodes 21-1 and 21-2 are fixed to the fixed electrode 21. −1 and 21-2 are displaced toward the fixed electrodes 21-1 and 21-2 by the electrostatic attractive force. For example, as shown in FIG. 4, when a driving voltage is applied to the fixed electrode 21-2, the movable beam 13-2 is displaced toward the fixed electrode 21-2. As a result, the mirror 14 rotates in one direction around an axis parallel to the x-axis (hereinafter referred to as the main axis). Conversely, when a drive voltage is applied to the fixed electrode 21-1, the movable beam 13-1 is displaced toward the fixed electrode 21-1, so that the mirror 14 rotates in the other direction around the main axis. Thereby, the mirror 14 can be rotated in both directions around the main axis.

  When the movable beams 13-1 and 13-2 are displaced in this way, as described above, the outer shape of the protrusions 21a to 21c is larger than the outer shapes of the openings 13a to 13c of the movable beams 13-1 and 13-2. Since the projections 21a to 21c are located in the openings 13a to 13c when the electrode substrate 20 is viewed from the mirror substrate 10 side, the protrusions 21a to 21c are located in the openings 13a to 13c. It does not contact the beams 13-1 and 13-2. Thereby, since the movable beams 13-1 and 13-2 can be displaced smoothly, the mirror 4 can also rotate smoothly as a result.

Further, the electrostatic attractive force acting on the movable beam 13 increases as the distance between the fixed electrode and the movable beam becomes shorter. Therefore, in the present embodiment, the protruding portions 21a to 21c are provided on the fixed electrodes 21-1 and 21-2 so that the distance from the movable beams 13-1 and 13-2 is reduced. Thereby, the movable beams 13-1 and 13-2 can be displaced smoothly.
In addition, since the plurality of projecting portions 21a to 21c are provided along the extending direction of the movable beam, any one projecting portion is positioned in the opening of the movable beam, and thus the projecting portion faces the fixed electrode. Even if the displacing force does not work, the other projecting portion is not located in the opening, so that the displacing force works toward the fixed electrode. As a result, the movable beam can continue to be displaced toward the fixed electrode.

  Further, when a drive voltage is applied to one of the mirror drive electrodes 22-1 and 22-2, the mirror 14 disposed opposite to the mirror drive electrodes 22-1 and 22-2 is caused to electrostatically attract the mirror drive electrode 22 by the electrostatic attraction. -Displacement toward 1, 22-2. For example, as shown in FIG. 5, when a drive voltage is applied to the mirror drive electrode 22-2, the region of the mirror 14 facing the mirror drive electrode 22-2 is displaced toward the mirror drive electrode 22-2. As a result, the mirror 14 rotates in one direction around an axis parallel to the y-axis (hereinafter referred to as the sub-axis). Conversely, when a drive voltage is applied to the mirror drive electrode 22-1, the region of the mirror 14 facing the mirror drive electrode 22-1 is displaced toward the mirror drive electrode 22-1, so that the mirror 14 is rotated around the sub-axis. It rotates in the other direction. Thereby, the mirror 14 can be rotated in both directions around the auxiliary shaft.

  Thus, the micromirror element 1 according to the present embodiment can be rotated around two axes, ie, the main axis and the sub axis.

<Configuration of micromirror array>
By arranging such micromirror elements 1 in a row in the short direction of the mirror 14, that is, in the x-axis direction, a micromirror array 2 as shown in FIGS. 6 and 7 can be configured.
Here, the micromirror arrays 1 are arranged in a line along a pair of support members 12 arranged in parallel to each other. Between the fixed electrodes 21-1 and 21-2 of the adjacent micromirror elements 1, a rectangular parallelepiped wall-like member 26 to which the same potential as the mirror 14 is applied is erected.

  Further, a plate-like member 30 may be further disposed on the mirror substrate 10. The plate-like member 30 is formed in a substantially rectangular flat plate shape in plan view, and is disposed above each of the movable beams 13-1 and 13-2. Such a plate-shaped member 30 is disposed on the mirror substrate 10 by being positioned so as to cover the movable beams 13-1 and 13-2 and being fixed to the upper end of the support member 12.

<Electric field shielding effect in micromirror array>
The electric field shielding effect in such a micromirror array 2 will be described with reference to FIGS.

  In the micromirror array 2 shown in FIG. 8, a wall-like member 26 for electric field separation is formed between adjacent fixed electrodes 21-1 and 21-2. The wall member 26 is connected so as to have the same potential as the mirror 14. With this configuration, when the movable beams 13-1 and 13-2 are driven, the electric field formed by the fixed electrodes 21-1 and 21-2 is separated for each micromirror element 1 by the wall-like member 26. It is possible to reduce the interference of the electric field with the matching micromirror element 1. Thereby, it can prevent operating under the influence of the electric field of the adjacent micromirror element 1.

  Further, when the movable beams 13-1 and 13-2 are driven and the projecting portions 21a to 21c are located in the openings 13a to 13c of the movable beams 13-1 and 13-2, the projecting portions in the openings 13a to 13c. The electric field formed by 21a-21c is shielded by the openings 13a-13c. Also by this, it is possible to reduce the interference of the electric field with the adjacent micromirror elements 1, and as a result, it is possible to prevent malfunction of the adjacent micromirror elements 1.

  Here, the wall-shaped member 26 exists only between the adjacent micromirror elements 1. On the other hand, in the conventional micromirror array, since the fixed electrode has a substantially U-shaped cross section, two wall-shaped members exist between the adjacent micromirror elements 1. Therefore, in this embodiment, the distance between adjacent micromirror elements can be made narrower than before, and as a result, the micromirror array can be reduced in size.

Further, as shown in FIG. 9, by providing a flat plate-like member 30 above the movable beams 13-1 and 13-2, the electric field distributed above the movable beams 13-1 and 13-2 can be reduced. Each mirror element 1 can be separated.
Conventionally, the shield cap provided above the micromirror element in order to reduce the interference of the electric field has to be arranged so that the groove is positioned immediately above the movable beam in order to prevent contact with the movable beam.
However, in the present embodiment, when the movable beams 13-1 and 13-2 are attracted to the fixed electrodes 21-1 and 21-2, the microscopic effect is caused by the shielding effect of the grounded movable beams 13-1 and 13-2. Since the electric field for each mirror element 1 is separated, the interference of the electric field can be sufficiently reduced even if the plate-like member 30 is disposed at a position relatively far above the movable beams 13-1 and 13-2. Therefore, since a simple flat plate structure in which a groove is not provided in the plate-like member as in the prior art may be used, the manufacturing cost can be reduced, and the mirror substrate 10 and the plate-like member 30 can be more easily aligned.

<Manufacturing method of micromirror element and micromirror array>
Next, a method for manufacturing the micromirror element and the micromirror array according to this embodiment will be described.

  The mirror substrate 10 is integrally formed, for example, by processing an SOI (Silicon On Insulator) substrate by MEMS technology. The SOI substrate is provided with an SOI layer made of thin silicon via a buried insulating layer on a thick base portion made of silicon. By processing this SOI layer, the movable beams 13-1 and 13-2 are provided. In addition, plate-like structures such as the mirror 14 and the spring members 15-1 and 15-2 can be formed. At this time, peripheral portions such as the support member 12 connected to the movable beams 13-1 and 13-2 are also formed at the same time. After processing these structures, the base portion is dug by dry etching, and the embedded insulating layer is removed, so that the respective portions are movable. A reflective film (not shown) formed on the mirror 14 is formed by depositing a desired metal by, for example, sputtering or vapor deposition.

  On the other hand, the electrode substrate 20 can be formed by using a generally well-known method for manufacturing a semiconductor device such as an LSI integrated circuit. The fixed electrodes 21-1 and 21-2 and the mirror drive electrodes 22-1 and 22-2 formed on the surface of the electrode substrate 20 can be formed by gold plating or the like. Further, by dividing the plating formation process, it is possible to easily form protrusions on electrodes having different heights, electrode walls for electric field separation, and the like.

  Further, 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 providing a support structure. The electrode substrate 20 may be formed. Single crystal silicon has a significantly lower etching rate due to alkali in the (111) plane than in the (100) plane or the (110) plane. By utilizing this phenomenon, a support structure such as the gap control bump 23 can be formed. The micromirror element is completed by bonding the periphery of the opening 11 of the mirror substrate 10 to the gap control bumps 23 of the electrode substrate 20 thus formed.

  Moreover, you may make it use the support structure prepared separately. For example, a support structure formed by solder bumps or plating may be used. Further, the mirror part and the electrode part may be laminated and integrally formed by surface micromachining.

When manufacturing a micromirror array 2 in which a plurality of such micromirror elements 1 are arranged, a plurality of movable beams 13-1 and 13 are mounted on the mirror substrate 10 by a method equivalent to the method for manufacturing the micromirror element 1 described above. −2, the mirror 14 and the spring members 15-1 and 15-2 are formed, and a plurality of fixed electrodes 21-1 and 21-2 and mirror drive electrodes 22-1 and 22-2 are formed on the electrode substrate 20. Further, a wall-like member 26 is formed between the fixed electrodes 21-1 and 21-2 of the adjacent micromirror elements 1, and between the mirror drive electrodes 22-1 and 22-2 of the adjacent micromirror elements 1. The wall-shaped member 26 is also formed. These wall-like members 26 can be formed by, for example, gold plating.
After the mirror substrate 10 thus formed and the electrode substrate 20 are bonded together, the plate member 30 is fixed to the upper end of the support member 12 of the mirror substrate 10, thereby completing the micromirror array 2.

  As described above, according to the present embodiment, the movable beams 13-1 and 13-2 have the openings 13a to 13c, and the fixed electrodes 21-1 and 21-2 protrude toward the openings 13a to 13c. By having the projecting portions 21a to 21c that perform, it becomes possible to reduce the interference of the electric field between the fixed electrodes 21-1 and 21-2 of the adjacent micromirror elements 1, so that the adjacent fixed electrodes 21-1, The distance 21-2 can be shortened, and as a result, downsizing can be realized.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, three movable beams and three fixed electrodes are provided in the micromirror element of the first embodiment. Therefore, in the present embodiment, the same name and reference numeral are assigned to the same configuration as that of the first embodiment, and the description thereof is omitted as appropriate.

  As shown in FIGS. 10 and 11, the micromirror element 1 ′ according to the present embodiment includes a mirror substrate 10 ′ and an electrode substrate 20 ′ disposed to face the mirror substrate 10 ′.

  The mirror substrate 10 ′ is formed in the opening 11, the opening 11 having a substantially rectangular shape in plan view, a pair of support members 12 positioned on a pair of opposite sides of the opening 11 and arranged in parallel to each other, Three movable beams 13-1 to 13-3 whose one end is fixed to the support member 12 and whose other end can be displaced, a mirror 14 connected to the other end of the movable beam, the movable beam 13 and the mirror 14 Spring members 15-1 to 15-3 are connected.

The movable beams 13-1 to 13-3 are formed in a substantially rectangular plate shape in plan view, the longitudinal direction is along the y-axis direction, one short side (fixed end) is fixed to the support member 12, and the other short side Spring members 15-1 to 15-3 corresponding to the sides (movable ends) are connected. In the present embodiment, the movable beam 13-1 has one end fixed to one support member 12 and the other end connected to the center of one of the pair of opposite sides of the mirror 14 as a spring member 15-1. Is connected. On the other hand, the movable beams 13-2 and 13-3 have one end fixed to the other support member 12 and the other end connected to the end of the other side of the pair of opposite sides of the mirror 14 as a spring member 15-2. Or the spring member 15-3 is connected.
The movable beams 13-1 to 13-3 are formed with three openings 13a to 13c along the extending direction.

On the other hand, fixed electrodes 21-1 to 21-3 having a substantially rectangular shape in plan view are formed on the electrode substrate 20 ′ at positions facing the movable beams 13-1 to 13-3. Further, on the electrode substrate 20 ′, a gap control bump 23 protruding in the z-axis direction is formed to fix the mirror substrate 10 ′ at a predetermined distance. Further, wirings 24 connected to the fixed electrodes 21-1 to 21-3 are formed in the electrode substrate 20 ′. Furthermore, a wall-like member 26 is erected between the fixed electrode 21-2 and the fixed electrode 21-3.
Here, the fixed electrodes 21-1 to 21-3 have projecting portions 21 a to 21 c that project toward the three openings 13 a to 13 c of the movable beams 13-1 to 13-3 arranged to face each other.

<Operation of micromirror element>
Next, the operation of the micromirror element 1 'according to the present embodiment will be described with reference to FIGS.

  First, when a driving voltage is applied to the fixed electrode 21-1, or the fixed electrodes 21-2 and 21-3, the movable beam 13-1 or the movable beam 13 disposed to face the fixed electrodes 21-1 to 21-3. -2, 13-3 are displaced toward the fixed electrodes 21-1, 21-2 by electrostatic attraction. For example, as shown in FIG. 12, when a driving voltage is applied to the fixed electrodes 21-2 and 21-3, the movable beams 13-2 and 13-3 are displaced toward the fixed electrodes 21-2 and 21-3. As a result, the mirror 14 rotates in one direction around an axis parallel to the x-axis (hereinafter referred to as the main axis). Conversely, when a drive voltage is applied to the fixed electrode 21-1, the movable beam 13-1 is displaced toward the fixed electrode 21-1, so that the mirror 14 rotates in the other direction around the main axis. Thereby, the mirror 14 can be rotated in both directions around the main axis.

  Further, when a drive voltage is applied to either one of the fixed electrodes 21-2 and 21-3, the movable beam 13-2 or the movable beam 13-3 disposed so as to face the fixed electrodes 21-2 and 21-3 is static. Displacement toward the fixed electrodes 21-2 and 21-3 due to the electric attractive force. For example, as shown in FIG. 13, when a driving voltage is applied to the fixed electrode 21-3, the movable beam 13-3 is displaced toward the fixed electrodes 21-2 and 21-3. Thereby, the mirror 14 rotates in one direction around an axis (hereinafter referred to as a sub-axis) passing through the connecting portion with the spring member 15-1. On the contrary, when a driving voltage is applied to the fixed electrode 21-2, the movable beam 13-2 is displaced toward the fixed electrode 21-2, so that the mirror 14 rotates in the other direction around the auxiliary. Thereby, the mirror 14 can be rotated in both directions around the auxiliary shaft.

  As described above, the micromirror element 1 ′ according to the present embodiment can be rotated around two axes, ie, the main axis and the sub axis.

<Configuration of micromirror array>
By arranging such micromirror elements 1 ′ in a line in the x-axis direction, a micromirror array 2 ′ as shown in FIGS. 14 and 15 can be configured.
Here, each micromirror array 1 'is arranged in a line along a pair of support members 12 arranged in parallel to each other. The main difference from the micromirror array 2 according to the first embodiment is that the number of movable beams and fixed electrodes provided between the mirrors 14 is different, so that the micromirror element 1 can be alternately switched. 'Is an array. Thereby, micromirror element 1 'can be arrange | positioned more densely.

Further, a rectangular parallelepiped wall member 26 having the same potential as the mirror 14 is provided between the fixed electrodes 21-1 to 21-3 of the adjacent micromirror elements 1 ′.
Furthermore, a plate-like member 30 may be further disposed on the mirror substrate 10 ′.

  The micromirror element 1 ′ and the micromirror array 2 ′ having such a configuration can be manufactured by a method equivalent to the micromirror element 1 and the micromirror array 2 in the first embodiment described above.

  As described above, according to the present embodiment, the movable beams 13-1 to 13-3 have the openings 13a to 13c, and the fixed electrodes 21-1 to 21-3 protrude toward the openings 13a to 13c. By having the protruding portions 21a to 21c that perform, it becomes possible to reduce the interference of the electric field between the fixed electrodes 21-1 to 21-3 of the adjacent micromirror element 1 ′, and therefore the adjacent fixed electrodes 21-1 The distance of ˜21-3 can be shortened, and as a result, downsizing can be realized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, four movable beams and four fixed electrodes are provided in the micromirror element of the first embodiment. Therefore, in the present embodiment, the same name and reference numeral are assigned to the same configuration as that of the first embodiment, and the description thereof is omitted as appropriate.

  As shown in FIGS. 16 and 17, the micromirror element 1 ″ according to the present embodiment includes a mirror substrate 10 ″ and an electrode substrate 20 ″ arranged to face the mirror substrate 10 ″.

  The mirror substrate 10 ″ is formed in the opening 11, the opening 11 having a substantially rectangular shape in plan view, a pair of support members 12 positioned on a pair of opposite sides of the opening 11 and arranged in parallel to each other, Four movable beams 13-1 to 13-4 having one end fixed to the support member 12 and the other end being displaceable, a mirror 14 connected to the other end of the movable beam, the movable beam 13 and the mirror 14 And spring members 15-1 to 15-4.

The movable beams 13-1 to 13-4 are formed in a substantially rectangular plate shape in plan view, the longitudinal direction is along the y-axis direction, one short side (fixed end) is fixed to the support member 12, and the other short side Spring members 15-1 to 15-4 corresponding to the sides (movable ends) are connected. In the present embodiment, each of the movable beams 13-1 and 13-4 is a spring having one end fixed to one support member 12 and the other end connected to an end of one side of a pair of opposite sides of the mirror 14. The member 15-1 or the spring member 15-4 is connected. On the other hand, the movable beams 13-2 and 13-3 have one end fixed to the other support member 12 and the other end connected to the end of the other side of the pair of opposite sides of the mirror 14 as a spring member 15-2. Or the spring member 15-3 is connected.
The movable beams 13-1 to 13-4 are formed with three openings 13a to 13c along the extending direction.

On the other hand, fixed electrodes 21-1 to 21-4 having a substantially rectangular shape in plan view are formed on the electrode substrate 20 ″ at positions facing the movable beams 13-1 to 13-4. A gap control bump 23 is formed on the electrode substrate 20 so as to protrude in the z-axis direction to fix the mirror substrate 10 at a predetermined distance apart from the fixed electrode 21-1 to 21-21. 4 is formed between the fixed electrode 21-1 and the fixed electrode 21-4 and between the fixed electrode 21-2 and the fixed electrode 21-3. A shaped member 26 is erected.
Here, the fixed electrodes 21-1 to 21-4 have projecting portions 21 a to 21 c that project toward the three openings 13 a to 13 c of the movable beams 13-1 to 13-4 arranged to face each other.

<Operation of micromirror element>
Next, the operation of the micromirror element 1 ″ according to the present embodiment will be described with reference to FIGS.

  First, when a driving voltage is applied to one of the fixed electrodes 21-1, 21-4 or the fixed electrodes 21-2, 21-3, the movable beam arranged to face the fixed electrode is moved toward the fixed electrode by electrostatic attraction. Displace. For example, as shown in FIG. 18, when a driving voltage is applied to the fixed electrodes 21-2 and 21-3, the movable beams 13-2 and 13-3 are displaced toward the fixed electrodes 21-2 and 21-3. As a result, the mirror 14 rotates in one direction around an axis parallel to the x-axis (hereinafter referred to as the main axis). Conversely, when a driving voltage is applied to the fixed electrodes 21-1, 21-4, the movable beams 13-1, 13-4 are displaced toward the fixed electrodes 21-1, 21-4. Rotate in the other direction around. Thereby, the mirror 14 can be rotated in both directions around the main axis.

  Further, when a drive voltage is applied to one of the fixed electrodes 21-1, 21-2 or the fixed electrodes 21-3, 21-4, the movable beam arranged to face the mirror drive electrode is fixed by the electrostatic attraction. Displace towards For example, as shown in FIG. 19, when a driving voltage is applied to the fixed electrodes 21-3 and 21-4, the movable beams 13-3 and 13-4 are displaced toward the fixed electrodes 21-3 and 21-4. As a result, the mirror 14 rotates in one direction around an axis parallel to the y-axis (hereinafter referred to as the sub-axis). Conversely, when a driving voltage is applied to the fixed electrodes 21-1, 21-2, the movable beams 13-1, 13-2 are displaced toward the fixed electrodes 21-1, 21-2, so that the mirror 14 It rotates in the other direction around the axis. Thereby, the mirror 14 can be rotated in both directions around the auxiliary shaft.

  Thus, the micromirror element 1 ″ according to the present embodiment can be rotated around two axes, ie, the main axis and the sub axis.

<Configuration of micromirror array>
By arranging such micromirror elements 1 ″ in a line in the x-axis direction, a micromirror array 2 ″ as shown in FIGS. 20 and 21 can be configured.
Here, each micromirror array 1 ″ is arranged in a line along a pair of support members 12 arranged in parallel to each other.

Further, a rectangular parallelepiped wall member 26 having the same potential as the mirror 14 is provided between the fixed electrodes 21-1 to 21-4 of the adjacent micromirror elements 1 ″.
Further, a plate-like member 30 may be further disposed on the mirror substrate 10 ″.

  The micromirror element 1 ″ and the micromirror array 2 ″ having such a configuration can be manufactured by a method equivalent to the micromirror element 1 and the micromirror array 2 in the first embodiment described above.

  As described above, according to the present embodiment, the movable beams 13-1 to 13-4 have the openings 13a to 13c, and the fixed electrodes 21-1 to 21-4 protrude toward the openings 13a to 13c. By having the projecting portions 21a to 21c that perform, it becomes possible to reduce the interference of the electric field between the fixed electrodes 21-1 to 21-4 of the adjacent micromirror element 1 ", so that the adjacent fixed electrodes 21-1 The distance of ˜21-4 can be shortened, and as a result, downsizing can be realized.

  In the first to third embodiments, the case where the number of the openings of the movable beam and the number of protrusions of the fixed electrode is three has been described as an example. However, the number is not limited to three, and can be freely set as appropriate. Can be set to Further, the planar shape of the opening is not limited to a rectangle, and can be set as appropriate, such as a circle, a hexagon, a trapezoid, and an ellipse. Similarly, the shape of the protruding portion is not limited to a rectangular parallelepiped shape, and can be arbitrarily set as appropriate, such as a cylinder, a prism, a truncated cone, and a truncated pyramid.

  In the first to third embodiments, the case where the movable beam has a substantially rectangular planar shape has been described as an example. However, the planar shape of the movable beam is not limited to this, and may be, for example, a triangle or a trapezoid. Or the width can be increased from the fixed end toward the movable end, or can be set as appropriate. In particular, since the movable beam is deformed by electrostatic attraction, its own rigidity greatly affects the amount of deformation. Therefore, the movable beam can be driven with desired characteristics by appropriately setting the planar shape.

  In the first to third embodiments, the case where the mirror 14 is substantially rectangular in plan view has been described as an example. However, the planar shape of the mirror 14 is not limited to this, for example, a parallelogram, a hexagon, A circle, an ellipse, a trapezoid, etc. can be set freely as appropriate. In these shapes, the return light from the mirror end can be suppressed by increasing the area from the end to which the spring member is connected toward the center.

  Further, in the first to third embodiments, the case where an electrode substrate having a fixed electrode is provided below the mirror substrate and the movable beam is displaced downward has been described as an example. Electrodes may be provided, or fixed electrodes may be provided both above and below the movable beam.

  In the first to third embodiments, the case where the shape of the spring member is substantially H-shaped in plan view has been described as an example. However, the shape of the spring member is not limited to this, and for example, a zigzag folded shape is appropriately used. It can be set freely.

  The present invention can be applied to various devices that rotatably support a structure such as a mirror.

  DESCRIPTION OF SYMBOLS 1,1 ', 1 "... micromirror element, 2,2', 2" ... micromirror array, 10,10 ', 10 "... mirror substrate, 11 ... opening, 12 ... support member, 13-1-13 -4 ... Movable beam, 14 ... Mirror, 15-1 to 15-4 ... Spring member, 20, 20 ', 20 "... Electrode substrate, 21a-21c ... Projection, 21-11-21-4 ... Fixed electrode, 22-1, 22-2 ... mirror drive electrode, 23 ... gap control bump, 24, 25 ... wiring, 26 ... wall member, 30 ... plate member.

Claims (8)

A reflector having a support member, a movable beam having one end fixed to the support member and the other end being displaceable, and a mirror connected to the other end of the movable beam via a spring member;
A fixed electrode disposed opposite to the movable beam on a surface separated from the reflecting portion,
The movable beam has an opening;
The said fixed electrode has a protrusion part which protrudes toward the said opening. The micromirror element characterized by the above-mentioned. The micromirror element according to claim 1, wherein
The movable beam has a plurality of openings along the extending direction;
The fixed electrode has a plurality of protrusions protruding toward the openings, respectively. The micromirror element, wherein: The micromirror element according to claim 1 or 2,
A plurality of the movable beams arranged opposite to each other with the mirror interposed therebetween;
A micromirror element comprising: a plurality of fixed electrodes facing each of the plurality of movable beams. In the micromirror element according to claim 3,
A plurality of the movable beams arranged parallel to each other;
And a plurality of the fixed electrodes arranged in parallel to each other. In the micromirror element according to any one of claims 1-4,
A micromirror element characterized by further comprising a wall-like member that is erected between two adjacent fixed electrodes arranged in parallel to each other and made of a conductor.   A micromirror array comprising a plurality of the micromirror elements according to any one of claims 1-5 arranged so that the movable beams are arranged in an array. The micromirror array according to claim 6, wherein
A micromirror array, further comprising: a flat plate-like member disposed above the movable beam. The micromirror array according to claim 6 or 7,
A micromirror array, further comprising a wall-like member that is provided between the fixed electrodes of the adjacent micromirror elements and is made of a conductor.