JP4595373B2 - Microactuator, microactuator array and optical device - Google Patents

Description

  The present invention relates to a microactuator, a microactuator array, and an optical device. This optical device can be used in, for example, an optical communication device or an optical transmission device.

  With the progress of micromachining technology, the importance of microactuators is increasing in various fields. As an example of a field in which microactuators are used, for example, an optical switch used for optical communication or the like to switch an optical path can be cited. Examples of such optical switches include the optical switches disclosed in Patent Documents 1 and 2 below.

  The microactuator includes a substrate and a movable portion that is supported by the substrate and can move with respect to the substrate, and the movable portion is formed of a thin film. A microactuator of a type in which the movable part has a cantilever structure (for example, FIG. 26, FIG. 36 to FIG. 40 of Patent Document 1), or a microactuator of a type in which the movable part has a double-supported structure (for example, Patent Document 2). 10 and 11) are known. In these microactuators, the movable part has an elastic part (for example, a leaf spring part constituting a beam part in a microactuator having a cantilever structure and a flexure part in a microactuator having a both-ends structure). And it can move with respect to the substrate according to the deformation of the elastic portion. In these microactuators, the elastic portion is provided symmetrically with respect to a predetermined plane perpendicular to the surface of the substrate so that the movable portion assumes a desired posture.

  In each optical switch disclosed in Patent Documents 1 and 2, the mirror support structure is different, but in any optical switch, a mirror is mounted on a portion that becomes a mirror support substrate plate in the movable part perpendicular to the surface. ing. In these optical switches, the mirror is driven by the microactuator to move up and down, and when the mirror advances into the incident optical path, the light is reflected by the mirror, while when the mirror leaves the incident optical path, the light is reflected. By going straight, the outgoing optical path is switched. In these optical switches, a wiring pattern for guiding an electric signal to be supplied to give a driving force or the like to the movable part is provided on the movable part and formed on the substrate.

Patent Document 1 also discloses an optical switch including a microactuator array in which a plurality of movable parts are arranged two-dimensionally on the same substrate, and a mirror mounted on each movable part.
International Publication No. 03/060592 Pamphlet JP 2001-42233 A

  However, in each of the conventional optical switches described above, the posture of the movable portion deviates from a desired posture because the movable portion is twisted about the same position as the axis of the movable portion in the predetermined plane. As a result, the angle of the mirror (mirror orientation) mounted on the movable part may deviate from the desired angle. In this case, when the mirror advances into the optical path and reflects light, the reflection direction is deviated from the desired direction, and an optical fiber or the like that guides reflected light arranged on the assumption that the mirror is completely vertical The optical coupling degree with the light source decreases, and the loss of light amount increases.

  In the above description, the microactuator used for the optical switch has been described as an example. However, in the case of the microactuator used for other optical devices and other devices, the posture of the movable portion of the microactuator is a desired posture. Various inconveniences may occur as a result of deviation from the above.

  The present invention has been made in view of such circumstances, and provides a microactuator, a microactuator array, and an optical apparatus using the microactuator that can reduce the deviation of the posture of the movable portion from a desired posture. For the purpose.

  As a result of the inventor's research, in the microactuator as described above, it has been found that one of the reasons why the attitude of the movable part deviates from the desired attitude is the influence of shape transfer by the wiring pattern formed on the substrate. did.

  That is, at the time of manufacturing the microactuator, a sacrificial layer is formed on the wiring pattern, a film constituting the movable portion is further formed thereon, and the sacrificial layer is finally removed. If a wiring pattern is formed on the substrate in a region facing the elastic part of the movable part, the step shape formed by the edge of the wiring pattern is transferred to the elastic part of the movable part by the thickness of the wiring pattern to be approximately the same shape. The Now, in a microactuator of a type in which the movable part has a cantilever structure, a case where the movable part has two beam parts (for example, FIGS. 26 and 36 to 40 in Patent Document 1) is taken as an example. explain. For each opposing region of the elastic part of the two beam portions of the movable part, when the wiring pattern is formed on the substrate in one opposing region and the wiring pattern is not formed in the other opposing region, both opposing regions When the wiring pattern is not formed symmetrically even if the wiring pattern is formed on the substrate, the step shape is transferred in one elastic portion, but the step shape is not transferred in the other elastic portion. Or the position of the step shape transferred by both elastic portions is different. As a result, since the elastic coefficients of the two elastic portions of the movable portion are different from each other, the posture of the movable portion deviates from a desired posture. In particular, in a microactuator array in which a plurality of the movable parts are arranged two-dimensionally on the same substrate, if an arrangement density of the movable parts is to be increased in order to reduce the size, a region where the wiring pattern can be given is limited. For this reason, it is often necessary to form a wiring pattern in a region of the movable portion facing the elastic portion.

  In addition, as a result of the inventor's research, in the microactuator as described above, an unintended electrostatic force acts between the wiring pattern provided on the movable part and the wiring pattern on the substrate opposite to the wiring pattern. It has been found that the posture of the movable part may deviate from a desired posture. That is, when different potentials are applied to the wiring pattern provided on the movable part and the wiring pattern on the substrate opposite to the wiring pattern, an electrostatic force is generated between them. Depending on the arrangement of each wiring pattern, the electrostatic force causes the movable portion to be twisted, and the movable portion is deviated from a desired posture.

  The present invention has been made on the basis of the results of investigation of the cause by the inventors. That is, in order to solve the above-described problem, the microactuator according to the first aspect of the present invention includes a substrate and a movable portion that is supported by the substrate and can move with respect to the substrate, and the movable portion is a thin film. The movable portion includes one or more elastic portions provided substantially symmetrically with respect to a predetermined plane perpendicular to the surface of the substrate, and the film pattern includes the one or more elastic portions. And formed on the substrate substantially symmetrically with respect to the predetermined surface in a region facing the portion.

  A microactuator according to a second aspect of the present invention has a cantilever structure in which a fixed end is fixed to the substrate in the first aspect.

  The microactuator according to a third aspect of the present invention is the microactuator according to the first or second aspect, wherein the movable part is mechanically connected in parallel between the fixed end and the free end of the movable part. First and second beam portions arranged symmetrically with respect to a predetermined plane, wherein the first beam portion includes one of the one or more elastic portions, and the second beam The part includes the other one of the one or more elastic parts.

  A microactuator according to a fourth aspect of the present invention is the microactuator according to any one of the first to third aspects, wherein at least a part of the film pattern is at least a part of a wiring pattern.

  The microactuator according to a fifth aspect of the present invention is the microactuator according to any one of the first to fourth aspects, wherein the movable portion has a wiring pattern, the wiring pattern is formed on the substrate, and the movable portion has the wiring pattern. An electrostatic shield layer is formed between at least a part of the wiring pattern and at least a part of the wiring pattern on the substrate facing the wiring pattern.

  A microactuator according to a sixth aspect of the present invention includes a substrate and a movable portion that is supported by the substrate and is movable with respect to the substrate, the movable portion having a wiring pattern, and wiring on the substrate. A pattern is formed, and an electrostatic shield layer is formed between at least a part of the wiring pattern of the movable part and at least a part of the wiring pattern on the substrate opposite to the wiring pattern.

  An optical device according to a seventh aspect of the present invention includes the microactuator according to any one of the first to sixth aspects and an optical element provided in the movable portion.

  An optical device according to an eighth aspect of the present invention includes a plurality of microactuators according to any one of the first to sixth aspects, and the movable parts of the plurality of microactuators are two-dimensionally arranged on the same substrate. It is a thing.

  An optical device according to a ninth aspect of the present invention includes the microactuator array according to the eighth aspect and optical elements respectively provided in the movable portions of the plurality of microactuators.

  According to the present invention, it is possible to provide a microactuator and a microactuator array that can reduce the deviation of the posture of the movable portion from a desired posture, and an optical device using the microactuator.

  Hereinafter, a microactuator, a microactuator array, and an optical device according to the present invention will be described with reference to the drawings.

  [First Embodiment]

  FIG. 1 is a schematic configuration diagram schematically showing an example of an optical system (in this embodiment, an optical switch system) including an optical switch array 1 as an optical device according to a first embodiment of the present invention. . For convenience of explanation, as shown in FIG. 1, an X axis, a Y axis, and a Z axis that are orthogonal to each other are defined (the same applies to the drawings described later). The surface of the substrate 11 of the optical switch array 1 is parallel to the XY plane. The direction of the arrow in the Z-axis direction is called the + Z direction or + Z side, and the opposite direction is called the -Z direction or -Z side, and the same applies to the X-axis direction and the Y-axis direction. The + side in the Z-axis direction may be referred to as the upper side, and the − side in the Z-axis direction may be referred to as the lower side. Further, the arrangement in the X-axis direction is called a column, and the arrangement in the Y-axis direction is called a row.

  As shown in FIG. 1, this optical switch system includes an optical switch array 1, m optical input optical fibers 2, m optical output optical fibers 3, and n optical output optical fibers 4. In response to the optical path switching state command signal, the optical path switching state indicated by the optical path switching state command signal is realized in response to the magnet 5 as a magnetic field generating unit that generates a magnetic field as will be described later with respect to the optical switch array 1. And an external control circuit 6 serving as a control unit for supplying a control signal to the optical switch array 1. In the example shown in FIG. 1, m = 3 and n = 3, but m and n may each be an arbitrary number.

  In the present embodiment, as shown in FIG. 1, the magnet 5 is a plate-like permanent magnet that is magnetized with an N-pole on the X-axis direction and an S-pole on the + side in the X-axis direction, and the lower side of the optical switch array 1. The magnetic field indicated by the magnetic force lines 5a is generated with respect to the optical switch array 1. That is, the magnet 5 generates a substantially uniform magnetic field toward the + side along the X-axis direction with respect to the optical switch array 1. However, instead of the magnet 5, for example, a permanent magnet having another shape, an electromagnet, or the like may be used as the magnetic field generation unit.

  As shown in FIG. 1, the optical switch array 1 includes a substrate 11 and m × n mirrors 31 arranged on the substrate 11. The m light input optical fibers 2 are arranged in a plane parallel to the XY plane so as to guide incident light from one side in the Y axis direction to the substrate 11 in the Y axis direction. The m optical output optical fibers 3 are arranged on the other side of the substrate 11 so as to face the m optical input optical fibers 2 and are not reflected by any mirror 31 of the optical switch array 1. Are arranged in a plane parallel to the XY plane so that light traveling in the Y-axis direction is incident on the XY plane. The n light output optical fibers 4 are arranged in a plane parallel to the XY plane so that light reflected by any mirror 31 of the optical switch array 1 and traveling in the X-axis direction is incident. . The m × n mirrors 31 can be moved in and out by a microactuator described later with respect to the intersection of the outgoing optical path of the m optical input optical fibers 2 and the incident optical path of the optical output optical fiber 4. It is arranged on the substrate 11 in a two-dimensional matrix so that it can move in the Z-axis direction. In this example, the orientation of the mirror 31 is set so that the normal line forms 45 ° with the X axis in a plane parallel to the XY plane. However, the angle can be changed as appropriate. When the angle of the mirror 31 is changed, the direction of the optical fiber 4 for light output may be set according to the angle. The optical path switching principle itself of this optical switch system is the same as the optical path switching principle of the conventional two-dimensional optical switch.

  FIG. 2 is a schematic plan view schematically showing the optical switch array 1 in FIG. The optical switch array 1 includes a substrate 11 (not shown in FIG. 2), m × n movable plates 12 arranged two-dimensionally on the substrate 11, and mirrors 31 mounted on each movable plate 12. And. In FIG. 1 and FIG. 2 and the drawings to be described later, nine optical switches are arranged in 3 rows and 3 columns for the sake of simplicity, but the number of optical switches is not limited at all. Portions other than the mirror 31 in the optical switch array 1 constitute a microactuator array. In FIG. 2, the leaf spring portion 12 c described later is hatched.

  Next, the structure of one optical switch as a unit element of the optical switch array 1 in FIG. 1 will be described with reference to FIGS.

  FIG. 3 is a schematic plan view schematically showing one optical switch as a unit element of the optical switch array 1 in FIG. FIG. 4 is a schematic cross-sectional view along the line A-A ′ in FIG. 3. However, FIG. 4 shows only a cross section of the movable plate 12. FIG. 5 is a diagram showing a pattern shape of the Al film 22 when the movable plate 12 in FIG. 3 is viewed from above. In order to facilitate understanding, in FIG. 5, the formation position of the Al film 22 is indicated by hatching. 6 and 7 are schematic cross-sectional views of the cross section taken along the line B-B ′ in FIGS. 3 and 5 as viewed from the + Y side in the −Y axis direction. However, FIGS. 6 and 7 also show the mirror 31 viewed in the −Y-axis direction. FIG. 6 shows a state in which the mirror 31 is held on the upper side and advances into the optical path, and FIG. 7 shows a state in which the mirror 31 is held on the lower side and retracts from the optical path. In FIGS. 6 and 7, for convenience of drawing, the convex portions 24 described later are not shown and are shown as having no step, and the movable plate 12 has a wiring pattern 42a and a fixed electrode 41a described later. It is shown that there is no step according to the shape transfer. In FIGS. 6 and 7, a wiring pattern 42a described later is shown on the assumption that the optical switches are arranged in two rows and two columns.

  As shown in FIGS. 2 and 3, one optical switch as a unit element of the optical switch array 1 is provided on a substrate 11 such as a silicon substrate or a glass substrate, and constitutes a microactuator together with the substrate 11. And a mirror 31 as an optical element which is a driven body mounted on the movable plate 12.

  The movable plate 12 is composed of a thin film, and as shown in FIGS. 3 to 7, the lower silicon nitride film (SiN film) 21 and the upper SiN film 23 over the entire planar shape of the movable plate 12, and these The intermediate Al film 22 is partially formed between the first and second films 21 and 23. That is, the movable plate 12 includes a part composed of a two-layer film in which SiN films 21 and 23 are laminated in order from the bottom, and a part composed of a three-layer film in which the SiN film 21, Al film 22, and SiN film 23 are laminated in order from the bottom. Have both. The pattern shape of the Al film 22 is as shown in FIG. 5, which will be described later. The movable plate 12 faces upward with respect to the substrate 11 as shown in FIG. 6 due to the internal stress generated by the difference in thermal expansion coefficient between the SiN films 21 and 23 and the Al film 22 and the internal stress generated at the time of film formation ( The film is formed with a predetermined film thickness and film formation conditions so as to be curved in the + Z direction.

  As shown in FIG. 3, the movable plate 12 has a substantially symmetric structure with respect to a plane P parallel to the XZ plane (hereinafter referred to as “symmetric plane P”). As shown in FIG. 3, the movable plate 12 includes a rectangular mirror mounting plate 12a as a mounting portion for mounting the mirror 31 (that is, a support base for the mirror 31), and an end portion of the mirror mounting plate 12a. And two strip-shaped support plates 12b connected to each other. In the present embodiment, these two support plates 12b are two beam portions mechanically connected in parallel to each other. The support plate 12b has a leg 12e and a leg 12f at each end. The leg portions 12e and 12f are both fixed to the substrate 11, and the movable plate 12 is mounted with a mirror as shown in FIG. 6, with the connecting portions 12d in the vicinity of the leg portions 12e and 12f of each support plate 12b as fixed ends. The plate 12a side is lifted. Thus, in the present embodiment, the movable plate 12 is a movable portion having a cantilever structure with the connection portion 12d as a fixed end. In the present embodiment, the substrate 11 and insulating films 13, 14, 15 and the like, which will be described later, laminated on the substrate 11 constitute a fixed portion. Strictly speaking, the connecting portion 12d in the support plate 12b is a fixed portion because the planarity is maintained by the convex portion 24 described later.

  As shown in FIG. 3, the movable plate 12 is provided with a convex portion 24 so as to surround a region including a portion where the mirror 31 of the movable plate 12 is mounted. As shown in FIG. 4, the convex portion 24 is formed by making the multilayer film constituting the movable plate 12 convex. By providing the convex portion 24 as described above, a step is generated. Therefore, in the movable plate 12, the region surrounded by the convex portion 24 and the region provided with the convex portion 24 (that is, the leaf spring portion 12c in the movable plate 12). In other regions (including the connection portion 12d), the bending due to the internal stress is suppressed, and the planarity can be maintained. Therefore, even when the movable plate 12 is in a state where the mirror 31 is lifted to the upper position by bending due to internal stress as shown in FIG. The shape of the mirror 31 can be kept constant.

  As described above, in the movable plate 12, the curvature is suppressed in the region surrounded by the convex portion 24 and the region where the convex portion 24 is provided, but the convex portion 24 is provided in the intermediate region of the support plate 12c. Absent. As a result, the intermediate region of the support plate 12c not provided with the convex portion 24 becomes a leaf spring portion 12c as an elastic portion, and the movable plate 12 is connected to the connection portions in the vicinity of the leg portions 12e and 12f by the curvature of the leaf spring portion 12c. With the fixed end 12d, the mirror mounting plate 12a side is raised as shown in FIG. The leaf spring portions 12 c of the two support plates 12 b are provided symmetrically with respect to the symmetry plane P perpendicular to the substrate 11. In the present invention, instead of the two support plates 12b, for example, one wide support plate 12b or three or more support plates may be provided symmetrically with respect to the symmetry plane P. Good. When the single support plate 12b is provided symmetrically with respect to the symmetry plane P, the support plate 12b may be arranged so that the center line in the width direction is included in the symmetry plane P.

  Here, the shape of the Al film 22 of the movable plate 12 will be described with reference to FIG. In the present embodiment, in order to drive the movable plate 12 using both Lorentz force and electrostatic force as driving forces, the Al film 22 is patterned into a shape as shown in FIG.

  The pattern 22 a of the Al film 22 extends from one of the two leg portions 12 f along the outer peripheral edge of the movable plate 12 to reach the tip of the movable plate 12, and then the opposite edge of the movable plate 12. Is the pattern that reaches the other leg 12f. The pattern 22a is used as a wiring for supplying a current for generating the Lorentz force when the movable plate 12 is driven by the Lorentz force. As shown in FIGS. 6 and 7, the pattern 22a is a Lorentz force wiring pattern made of an Al film through a through hole of the insulating film 15 on the substrate 11 and a contact hole of the SiN film 21 in the leg portion 12f on the + Y side. In addition, the leg portion 12f on the −Y side is similarly connected to another Lorentz force wiring pattern (not shown in FIGS. 6 and 7; see FIGS. 10 and 11 described later). A current as a Lorentz force drive signal is supplied from the Lorentz force wiring pattern via the portion 12f. A current path (Lorentz force) in which a linear wiring pattern extending in the Y-axis direction along the one side 12g of the tip of the movable plate 12 in the pattern 22a is arranged in a magnetic field and generates a Lorentz force as a driving force when energized. Current path). The other part of the pattern 22a is a wiring pattern of a current path for Lorentz force for supplying current to the linear wiring pattern. The Lorentz force current path is placed in the magnetic field in the X-axis direction by the magnet 5 shown in FIG. Accordingly, when a current is supplied to the pattern 22a, a Lorentz force in the + Z direction or the -Z direction is generated in the current path for Lorentz force depending on the direction of the current.

  As shown in FIGS. 6 and 7, insulating films 13, 14, 15 such as a silicon oxide film are sequentially stacked on the substrate 11 from the substrate 11 side, and the Lorentz force wiring pattern 42 a includes the insulating film 14. , 15 are formed.

  Further, the pattern 22b of the Al film 22 extends from each of the two leg portions 12e to the distal end side (+ X side) of the movable plate 12 along the inner edge of the movable plate 12, and is a rectangle disposed on the distal end side. Connected to the pattern 22d. The pattern 22d is a movable electrode for generating an electrostatic force as a driving force. Hereinafter, the pattern 22d may be referred to as the movable electrode 22d. The pattern 22 d is also a pattern in the Al film 22. The pattern 22b is a wiring pattern of the movable electrode 22d. The pattern 22b is a movable electrode wiring pattern 42b (not shown in FIGS. 6 and 7, not shown in FIGS. 6 and 7; see FIGS. 10 and 11 to be described later) through the through hole of the insulating film 15 and the contact hole of the SiN film 21 in the leg 12e. ) And a voltage (electrostatic force voltage, electrostatic force drive signal) is applied to the fixed electrode 41a made of an Al film. The fixed electrode 41a is formed between the insulating films 13 and 14 on the substrate 11, and is disposed at a position facing the movable electrode 22d. When a voltage is applied between the movable electrode 22d and the fixed electrode 35, an electrostatic force as a driving force is generated between them, and the movable plate 12 is attracted to the substrate 11 by this electrostatic force.

  In the present embodiment, the mirror 31 is held on the upper side (opposite the substrate 11) by controlling the electrostatic force voltage between the movable electrode 22d and the fixed electrode 41a and the current flowing through the Lorentz force current path. The state (FIG. 6) and the state where the mirror 31 is held on the lower side (substrate 11 side) (FIG. 7) can be obtained. In the present embodiment, as will be described later, such control is performed by the external control circuit 6a. 6 and 7, K indicates a cross section of the optical path of the incident light with respect to the advance position of the mirror 31.

  As shown in FIG. 6, in a state where the electrostatic force as the driving force and the Lorentz force as the driving force are not applied, the film is curved in the + Z direction by the stress (spring force) of the film of the leaf spring portion 12c. It returns and the mirror 31 is held on the upper side. As a result, the mirror 31 advances into the optical path K and reflects the light incident on the optical path K. When switching from this state to a state where the light incident on the optical path is allowed to pass through without being reflected by the mirror 31 (FIG. 7), for example, first, the Lorentz force as a driving force is applied to the leaf spring portion. The mirror 31 is moved downward against the stress (spring force) of the film 12c, and after the mirror 31 is held on the substrate 11 side, the electrostatic force as a driving force is applied to maintain the holding, The application of the Lorentz force may be stopped.

  As can be seen from the above description, in the present embodiment, the movable electrode 22d and the fixed electrode 41a that generate an electrostatic force as a driving force, and the Lorentz force current path that generates a Lorentz force as a driving force are: In accordance with the signal, a driving force applying means that can apply to the movable plate 12 a driving force for moving and maintaining the position of the mirror 31 against the spring force of the leaf spring portion 12c of the movable plate 12 is configured. .

  However, in the present invention, the driving force applying means may be configured by only one of the movable electrode 22d, the fixed electrode 41a, and the Lorentz force current path, for example. In the case where the driving force applying means is composed of only the movable electrode 22d and the fixed electrode 41a, for example, the pattern 22a may be removed or disconnected in the middle. In the case where the driving force applying means is constituted only by the Lorentz force current path, for example, the pattern 22b may be removed, the wire may be disconnected in the middle, or the movable electrode 22d may be removed.

  In the present embodiment, the mirror 31 is made of Au, Ni, or other metal like the mirror disclosed in Patent Document 2, and stands upright on the upper surface of the mirror mounting plate 12a of the movable plate 12, It is simply fixed. For example, as disclosed in Patent Document 2, the mirror 31 is formed by forming a recess corresponding to the mirror 31 in a resist, and then growing Au, Ni, and other metals to be the mirror 31 by electrolytic plating. Then, it can be formed by removing the resist. The support structure for supporting the mirror 31 by the mirror mounting plate 12a as the support base is not limited to this, and for example, the support structure disclosed in Patent Document 1 may be adopted. In that case, the support structure and the mirror 31 can be manufactured by a manufacturing method similar to the manufacturing method disclosed in Patent Document 1.

  FIG. 8 is an electric circuit diagram showing the optical switch array 1 according to the present embodiment. The single optical switch shown in FIGS. 3 to 7 includes one capacitor (corresponding to a capacitor formed by the fixed electrode 41a and the movable electrode 22d) and one coil (for the Lorentz force) in terms of electric circuit. It can be regarded as a current path (a linear portion extending in the Y-axis direction along one side 12g of the tip of the movable plate 12)). In FIG. 8, the capacitors and coils of the optical switch of m rows and n columns are denoted as Cmn and Lmn, respectively. For example, the capacitor and coil of the optical switch (in the first row and the first column) in the upper left in FIG. 2 are denoted as C11 and L11, respectively. In the present embodiment, the left electrode in FIG. 8 of each capacitor is a fixed electrode 41a, and the right electrode in FIG. 8 is a movable electrode 22d. In FIG. 8, in order to simplify the description, nine optical switches are arranged in three rows and three columns as described above. However, the number of optical switches is not limited at all, and the principle is the same even when, for example, an optical switch having 100 rows and 100 columns is provided. Even if the number of optical switches is the same, the number of rows and columns need not be the same, and there is no need for a matrix arrangement. For example, when the number of optical switches is nine, the arrangement may be one row and nine columns, and when the number of optical switches is 16, any arrangement of four rows and four columns, one row and sixteen columns, and two rows and eight columns. But you can.

  In the present embodiment, as can be seen from the above description, in the entire optical switch array 1, the Lorentz force wiring pattern 22a, the movable electrode 22d, and the movable electrode wiring pattern 22b provided on the movable plate 12 are provided. 9 are arranged as shown in FIG. In this embodiment, in the optical switch array 1, as shown in FIGS. 10 and 11, the Lorentz force wiring pattern 42a, the movable electrode wiring pattern 42b, the fixed electrode 41a, and the fixed electrode wiring pattern 41b are formed on the substrate. The electrical connection shown in FIG. 8 is realized. Note that the wiring pattern of the movable plate 12 and the wiring pattern on the substrate 11 are connected by leg portions 12e and 12f where they overlap each other.

  FIG. 9 is a schematic plan view showing the arrangement of the Lorentz force wiring pattern 22a, the movable electrode 22d, and the movable electrode wiring pattern 22b on the movable plate 12 in the entire optical switch array 1. FIG. FIG. 10 is a schematic plan view showing the arrangement of the Lorentz force wiring pattern 42a, the movable electrode wiring pattern 42b, the fixed electrode 41a, and the fixed electrode wiring pattern 41b on the substrate 11 in the entire optical switch array 1. FIG. FIG. 11 shows a part of FIG. 10 (Lorentz force wiring pattern 42a, movable electrode wiring pattern 42b, fixed electrode 41a on the substrate 11 in the vicinity of the region facing the movable plate 12 in the second row and second column in FIG. 10). And FIG. 4 is a schematic enlarged plan view in which the fixed electrode wiring pattern 41b) is enlarged. 10 and 11, the outer shape of the movable plate 12 (including the leaf spring portion 12c and the connection portion 12d) and the leg portions 12e and 12f are shown together by broken lines. The fixed electrode 41a and the fixed electrode wiring pattern 41b are formed between the insulating films 13 and 14 on the substrate 11 (see FIGS. 6 and 7). The Lorentz force wiring pattern 42 a and the movable electrode wiring pattern 42 b are formed between the insulating films 14 and 15 (see FIGS. 6 and 7) on the substrate 11.

  As shown in FIG. 8, the optical switch array 1 according to this embodiment includes a first terminal group including a plurality of terminals CD1 to CD3, a second terminal group including a plurality of terminals CU1 to CU3, and a plurality of terminals. A third terminal group consisting of L0 to L3 is provided. These terminals CD1 to CD3, CU1 to CU3, L0 to L3 are external connection terminals for connection to the external control circuit 6 in FIG. Although not shown in the drawings, the terminals CD1 to CD3, CU1 to CU3, L0 to L3 can be configured, for example, by using a part of the corresponding wiring pattern as an electrode pad.

  Further, in FIG. 8, the number of terminals CD1 to CD3 of the first terminal group is three as the number of rows of the optical switch, and the number of terminals CU1 to CU3 of the second terminal group is the number of columns of the optical switch. There are also three.

  In the present embodiment, the fixed electrodes 41a of the capacitors C11, C12, and C13 in the first row are electrically connected in common to the terminal CD1 of the first terminal group, and are electrically connected to the other terminals. Not. The fixed electrodes 41a of the capacitors C21, C22, C23 in the second row are electrically connected in common to the terminal CD2 of the first terminal group and are not electrically connected to the other terminals. The fixed electrodes 41a of the capacitors C31, C32, C33 in the third row are electrically connected in common to the terminal CD3 of the first terminal group, and are not electrically connected to the other terminals. Thus, the fixed electrode 41a of the microactuator of the row is electrically connected in common for each row. These electrical connections are realized by the fixed electrode wiring pattern 41b as shown in FIGS.

  The movable electrodes 22d of the capacitors C11, C21, C31 in the first column are electrically connected in common to the terminal CU1 of the second terminal group, and are not electrically connected to the other terminals. The movable electrodes 22d of the capacitors C12, C22, C32 in the second row are electrically connected in common to the terminal CU2 of the second terminal group, and are not electrically connected to the other terminals. The movable electrodes 22d of the capacitors C13, C23, and C33 in the third row are electrically connected in common to the terminal CU3 of the second terminal group, and are not electrically connected to the other terminals. In this way, the movable electrode 22d of the movable plate 12 of the microactuator in the row is electrically connected in common for each row. These electrical connections are realized by the movable electrode 22d and the movable electrode wiring patterns 22b and 42b, as shown in FIGS.

  In FIG. 8, the coils L11, L21, L31 in the first row are connected in series, one end of which is connected to the terminal L1 and the other end is connected to the terminal L0. The second row of coils L12, L22, and L32 are connected in series, with one end connected to the terminal L2 and the other end connected to the terminal L0. The third row of coils L13, L23, and L33 are connected in series, with one end connected to the terminal L3 and the other end connected to the terminal L0.

  The coils L11, L21, L31 in the first row have their current directions so that the directions of the Lorentz forces generated in these coils L11, L21, L31 are the same when a current is passed between the terminals L1, L0. Connected together. The same applies to the coils L12, L22, L32 in the second row and the coils L13, L23, L33 in the third row. In the present embodiment, when a current flows in the direction from the terminals L1, L2, L3 to the terminal L0 (the current in this direction is a positive current), the Lorentz force is applied to the current path for the Lorentz force of the microactuator. Is set to work downwards.

  Thus, in the example shown in FIG. 8, the current path for the Lorentz force of the microactuator in the row is electrically connected in series so that the Lorentz force in the same direction is generated when energized. Has been. These electrical connections are realized by Lorentz force wiring patterns 22a and 42a, as shown in FIGS.

  The optical switch array 1 according to the present embodiment is not equipped with an address circuit, a column selection switch, a row selection switch, or the like, as shown in FIG.

  In the present embodiment, the external control circuit 6 in FIG. 1 is connected to the terminals CD1 to CD3, CU1 to CU3, L0 to L3, and independently controls the potentials of the terminals CD1 to CD3, CU1 to CU3. At the same time, by independently controlling the currents flowing through the terminals L1 to L3, the optical path switching state of each optical switch of the optical switch array 1 is controlled. The external control circuit 6 responds to the optical path switching state command signal and supplies the control signal for realizing the optical path switching state indicated by the optical path switching state command signal to the terminals CD1 to CD3 and CU1 to CU3 and the terminal L1. ˜L3 is supplied as a current flowing through L3 to realize the optical path switching state. The specific circuit configuration of the external control circuit 6 is apparent from the operation example described below.

  FIG. 13 shows an example of a potential chart that the external control circuit 6 applies to the terminals CD1 to CD3 and CU1 to CU3 and a current chart that flows through the coils via the terminals L1 to L3. In the example shown in FIG. 13, the external control circuit 6 applies one of two potentials Vh and Vm1 to the terminals CD1 to CD3 of the first terminal group, and supplies the terminals CU1 to CU3 of the second terminal group. Gives one of two potentials Vm2 and VL. Here, the potentials Vh, Vm1, Vm2, and VL satisfy the relationship of Vh> Vm1 ≧ Vm2> VL. Either one of currents I1 (current in the direction in which the downward Lorentz force is generated) or -I2 (current in the direction in which the upward Lorentz force is generated) flows or no current flows in each of the terminals L1 to L3. (No current).

  In the example shown in FIG. 13, before time t1, the potentials of the terminals CD1 to CD3 are set to Vh, the potentials of the terminals CU1 to CU3 are set to VL, and no current flows through the terminals L1 to L3. It is assumed that all the actuators are in a latch release state (a state in which the movable plate 12 is positioned at the upper position as shown in FIG. 6).

  Between time t1 and time t2, a current I1 is supplied to the terminals L1, L2, and L3, and the movable plates 12 of all nine actuators move downward (on the substrate 11 side, that is, between the fixed electrode 41a and the movable electrode 22d). It is moved in the direction that the interval becomes narrower). As a result, the distance between the fixed electrode 41a and the movable electrode 22d of all the actuators becomes narrow, and when the electrostatic force between both electrodes exceeds a certain value, the movable plates 12 of all the actuators in FIG. As shown, it is latched (held) in the lower position.

  Between time t3 and time t4, the potential of the terminal CD1 is lowered from Vh to Vm1, the potential of the terminal CU1 is raised from VL to Vm2, and a current −I2 is supplied to the terminal L1. As a result, the voltage between the electrodes of the capacitor C11 in FIG. 8 decreases from Vh−VL to Vm1−Vm2. As the voltage between the electrodes of the capacitor C11 decreases, the electrostatic force between both electrodes of the capacitor C11 also decreases. On the other hand, the Lorentz force by the current −I2 acts in a direction to separate the fixed electrode 41a and the movable electrode 22d. Here, in the direction in which the Lorentz force and the spring force are separated from each other, the electrostatic force is in the direction in which the force is attracted. When the force in the direction in which the Lorentz force is separated is set to be stronger than the force in the direction to attract, the latch is released, 41a and movable electrode 22d are separated.

  Further, between time t3 and time t4, the voltage between both electrodes of the capacitors C12 and C13 is Vm1-VL. Since no current flows through the terminals L2 and L3, no Lorentz force is generated in the coils L12 and L13 of the microactuator corresponding to the capacitors C12 and C13. Therefore, if the electrostatic force generated by the voltage difference Vm1−VL is set to be larger than the spring force, the latch of the microactuator corresponding to the capacitors C12 and C13 is maintained.

  Furthermore, between time t3 and time t4, the voltage between both electrodes of the capacitors C21 and C31 is Vh−Vm2. Since the current -I2 flows through the terminal L1, an upward Lorentz force is generated in the coils L21 and L31 of the microactuator corresponding to the capacitors C21 and C31. Therefore, if the electrostatic force generated by the voltage Vh−Vm2 is set to be larger than the sum of the Lorentz force and the spring force, the latch of the microactuator corresponding to the capacitors C21 and C31 is maintained.

  Therefore, only the microactuator corresponding to the capacitor C11 is released from time t3 to time t4.

  Similarly to the time t3 to the time t4, only the microactuator corresponding to the capacitor C22 is released from the time t5 to the time t6, and only the fixed electrode 41a and the movable electrode 22d of the C33 are set between the time t7 and the time t8. Is released.

  Thus far, the initial mirror arrangement of the optical switch has been completed, in which the latches of the microactuators corresponding to the capacitors C11, C22, and C33 are released and the latches of the other microactuators are maintained.

  Further, a procedure for changing a part of the mirror arrangement from the initial arrangement will be described.

  Between time t9 and time t10, a current I1 flows through the terminal L1, and the movable plate 12 of the microactuator corresponding to the capacitor C11 moves downward (on the substrate 121 side, that is, the interval between the fixed electrode 41a and the movable electrode is narrowed). Direction). As a result, the distance between the fixed electrode 41a and the movable electrode 22d of the actuator corresponding to the capacitor C11 becomes narrow, and when the electrostatic force between both electrodes exceeds a certain value, the electrostatic force between the electrodes causes the actuator corresponding to the capacitor C11 to move. The plate 12 is latched in the lower position.

  Between time t11 and time t12, a current I1 flows through the terminal L2, and the movable plate 12 of the actuator corresponding to the capacitor 22 moves downward (on the substrate 121 side, that is, the interval between the fixed electrode 41a and the movable electrode 22d becomes narrower. Direction). As a result, the distance between the fixed electrode 41a and the movable electrode 22d of the actuator corresponding to the capacitor C22 becomes narrow, and when the electrostatic force between both electrodes exceeds a certain value, the electrostatic force between the electrodes causes the actuator corresponding to the capacitor C22 to move. The plate 12 is latched in the lower position.

  Between time t13 and time t14, the voltage at the terminal CD2 is lowered from Vh to Vm1, the potential at the terminal CU1 is raised from VL to Vm2, and a current -I2 is allowed to flow through the terminal L1. As a result, the voltage between the electrodes of the capacitor C21 in FIG. 8 decreases from Vh−VL to Vm1−Vm2. As the voltage between the electrodes of the capacitor 21 decreases, the electrostatic force between both electrodes of the capacitor C21 also decreases. On the other hand, the Lorentz force due to the current -I2 acts in the direction of separating the fixed electrode and the movable electrode. Here, in the direction in which the Lorentz force and the spring force are separated from each other, the electrostatic force is in the direction in which the force is attracted. And the movable electrode is pulled apart. At this time, the latches of the microactuators corresponding to other capacitors are maintained in the same manner as from time t1 to time t2.

  Between time t15 and time t16, the voltage at the terminal CD1 is lowered from Vh to Vm1, the potential at the terminal CU2 is raised from VL to Vm2, and a current -I2 is supplied to the terminal L2. As a result, the voltage between the electrodes of the capacitor C12 in FIG. 8 decreases from Vh-VL to Vm1-Vm2. As the voltage between the electrodes of the capacitor 12 decreases, the electrostatic force between both electrodes of the capacitor C12 also decreases. On the other hand, the Lorentz force by the current −I2 acts in a direction to separate the fixed electrode 41a and the movable electrode 22d. Here, in the direction in which the Lorentz force and the spring force are separated, the electrostatic force is in the direction in which the force is attracted. When the force in the direction in which the Lorentz force is separated becomes stronger than the force in the direction in which the force is attracted, the latch is released, 41a and movable electrode 22d are separated. At this time, the latches of the microactuators corresponding to other capacitors are maintained in the same manner as from time t1 to time t2.

  This completes the change in the mirror arrangement of the optical switch, in which the latches of the microactuators corresponding to the capacitors C21, C12, and C33 are released and the latches of the other microactuators are maintained.

  From the above operation explanation, it can be seen that a desired optical path switching state can be appropriately realized. The voltage values and current values described above may be determined as appropriate so that the above-described operation can be realized.

  In the example shown in FIG. 13, the external control circuit 6 controls the potentials of the fixed electrode and the movable electrode so that a DC voltage is applied as the voltage between the electrodes of the capacitor in each period. As shown in FIG. 2, the potentials of the fixed electrode and the movable electrode may be controlled so that an alternating voltage by a pulse is applied as the voltage between the electrodes of the capacitor in each period. FIG. 14 shows another example of a timing chart of potentials that the external control circuit 6 applies to the terminals CD1 to CD3 and CU1 to CU3 and currents that flow through the coils via the terminals L1 to L3. This corresponds to FIG.

  In FIG. 14, the movement of the movable electrode 22d of each microactuator at each time is the same as in the case of FIG. In the example shown in FIG. 14, the potentials applied to the fixed electrodes (potentials applied to the terminals CD1, CD2, and CD3) are pulse waveforms having the same phase and a duty of 50%, and in the positive and negative directions centering on the ground level. It swings symmetrically with amplitude Vh ′ or Vm. The potentials applied to the movable electrodes (potentials applied to the terminals CU1, CU2, CU3) are pulses having the same phase but opposite in phase to those applied to the terminals CD1, CD2, CD3, and the duty is 50%. There is a symmetrical swing with amplitude Vh ′ or Vm in the positive and negative directions around the ground level. The voltage between the electrodes of the capacitor is 2 × Vh ′ when the potential of the movable electrode and the potential of the fixed electrode are both amplitude Vh ′, Vm + Vh ′ when one is amplitude Vh ′ and the other is amplitude Vm, and both are amplitude Vm Is 2 × Vm. In the example shown in FIG. 14 as well, by appropriately setting each amplitude value and the like, the same operation as when a potential is supplied as shown in FIG. 13 can be realized. Note that, in each period, the terminals CD1 to CD3 and CU1 to CU3 may be given a potential that changes in a sine wave form in time instead of a potential that changes in a pulse form in time.

  Incidentally, among the fixed electrode wiring pattern 41b, the Lorentz force wiring pattern 42a and the movable electrode wiring pattern 42b formed on the substrate 11 side shown in FIGS. The pattern is a dummy wiring pattern that is not necessary for realizing the electrical connection shown in FIG. The feature of this embodiment is that these dummy wiring patterns are included.

  As a comparative example, a dummy wiring pattern (part indicated by a solid line in FIG. 15) is removed from the fixed electrode wiring pattern 41b, the Lorentz force wiring pattern 42a, and the movable electrode wiring pattern 42b shown in FIGS. Is shown in FIGS. 16 and 17. If the electrical connection shown in FIG. 8 is realized only from the viewpoint of electrical connection as in the prior art, the wiring pattern shown in FIGS. 10 and 11 employed in the present embodiment is used. The wiring pattern shown in FIGS. 16 and 17 from which the dummy wiring pattern is removed is employed.

  FIG. 16 is a schematic plan view showing the arrangement of the Lorentz force wiring pattern 42a, the movable electrode wiring pattern 42b, the fixed electrode 41a, and the fixed electrode wiring pattern 41b on the substrate 11 in the entire optical switch array according to the comparative example. This corresponds to FIG. FIG. 17 shows a part of FIG. 16 (Lorentz force wiring pattern 42a, movable electrode wiring pattern 42b, fixed electrode 41a on the substrate 11 in the vicinity of the region facing the movable plate 12 in the second row and second column in FIG. 16). And FIG. 11 is a schematic enlarged plan view enlarging the fixed electrode wiring pattern 41b). The optical switch array according to this comparative example is different from the optical switch array 1 according to the present embodiment only in that it does not include the dummy wiring pattern and the influence of the shape transfer described later.

  In the present embodiment, as shown in FIGS. 10 and 11, by including the dummy wiring pattern, in a region facing the region (including the region of the leaf spring portion 12 c) excluding the connection portion 12 d in the movable plate 12. For each movable plate 12, wiring patterns 41 b, 42 a, 42 b are formed symmetrically with respect to a symmetry plane P perpendicular to the substrate 11 related to the movable plate 12. On the other hand, in the comparative example, as shown in FIGS. 16 and 17, by not including the dummy wiring pattern, the wiring patterns 41b, 42a, and 42b are in the plane of symmetry P in the region facing the movable plate 12. It is asymmetric with respect to.

  The influence of the symmetry and asymmetry of the wiring pattern will be described while explaining the manufacturing method of the optical switch array according to the present embodiment and the comparative example with reference to FIGS.

  FIG. 12 is a schematic cross-sectional view schematically showing an intermediate state of the manufacturing process of the optical switch array 1 according to the present embodiment, and is a diagram showing an expanded cross-section along the line CC ′ in FIG. It is. 18 is a schematic cross-sectional view schematically showing a state in the middle of the manufacturing process of the optical switch array according to the comparative example (a state corresponding to the state shown in FIG. 12), taken along the line DD ′ in FIG. It is a figure which expands and shows the section which followed, and respond | corresponds to FIG.

  The optical switch array 1 according to the present embodiment can be manufactured by using a semiconductor manufacturing technique such as film formation and patterning, etching, and sacrificial layer formation / removal. A specific example will be briefly described with reference to FIG.

  First, the insulating film 13 is formed on the substrate 11. Next, an Al film is formed on the insulating film 13, and this Al film is patterned into the shape of the fixed electrode 41a and the fixed electrode wiring pattern 41b shown in FIGS. Next, an insulating film 14 is formed on the substrate in this state, and through holes for the leg portions 12e and 12d are formed in the insulating film 14 by a photolithography etching method or the like. Thereafter, an Al film is formed on the substrate in this state, and this Al film is patterned into the shapes of the Lorentz force wiring pattern 42a and the movable electrode wiring pattern 42b shown in FIGS. .

  Next, an insulating film 15 is formed on the substrate in this state, and through holes and the like for the leg portions 12e and 12d are formed in the insulating film 15. Next, a resist 100 as a sacrificial layer is formed on the substrate in this state, and openings for the leg portions 12e and 12d are formed in the resist 100. Further, a resist 101 is formed in an island shape on the resist 100 as a sacrificial layer for forming the convex portions 24. Thereafter, the SiN film 21 is formed, and the SiN film 21 is patterned into the shape of the movable plate 12 by a photolithography etching method or the like, and contact holes in the legs 12e and 12d are formed in the SiN film 21. FIG. 12 shows this state.

  Next, an Al film is formed on the substrate in this state, and this Al film is patterned into the shape of the Lorentz force wiring pattern 22a, the movable electrode wiring pattern 22b, and the movable electrode 22d shown in FIG. 9 by a photolithography etching method or the like. To do. Next, a SiN film 23 is formed and patterned into the shape of the movable plate 12 by a photolithographic etching method or the like.

  Thereafter, for example, as in the manufacturing method disclosed in Patent Document 1, a resist for forming a mirror is applied on the substrate in this state, and a recess corresponding to the mirror 31 is formed in the resist. Au, Ni and other metals to be the mirror 31 are grown by plating. Finally, the resists 100 and 101 and the mirror forming resist are removed by an ashing method or the like. Thus, the optical switch array 1 according to the present embodiment is completed.

  The optical switch array according to the comparative example can also be manufactured in the same manner as the optical switch array 1 according to the present embodiment. However, in the case of the comparative example, the Al film formed on the insulating film 13 is patterned into the shape of the fixed electrode 41a and the movable electrode wiring pattern 41b shown in FIGS. 16 and 17, and the Al film formed on the insulating film 14 is formed. The film is patterned into the shape of the Lorentz force wiring pattern 42a and the fixed electrode wiring pattern 42b shown in FIGS.

  As shown in FIGS. 12 and 18, the steps formed by the edges of the wiring patterns 41b, 42a, and 42b are substantially the same in shape according to the thickness (for example, at least about 500 nm) of the wiring patterns 41b, 42a, and 42b. It is transferred to each layer laminated thereon. Accordingly, the wiring patterns 41b, 42a, and 42b existing in the region facing the movable plate 12 have substantially the same step shape and the movable plate 12 (in FIGS. 12 and 18, only the SiN film 21 of the movable plate 12 is shown. Is transferred).

  In the present embodiment, as described above, by including the dummy wiring pattern, in the region facing the region excluding the connection portion 12d (including the region of the leaf spring portion 12c) in the movable plate 12, the wiring pattern 41b, 42a and 42b are formed symmetrically with respect to a line intersecting the plane of symmetry P of the movable plate 12 (see FIGS. 10 and 11).

  In the present embodiment, since the wiring patterns 42a and 42b are formed symmetrically with respect to the plane of symmetry P in the region facing the two leaf spring portions 12c of one movable plate 12 as described above, 2 A symmetrical step shape with respect to the symmetry plane P appears in the two leaf spring portions 12c. For example, as shown in FIG. 12, there are symmetrical steps in the SiN film 21 at the location M1 (location of one leaf spring portion 12c) and the SiN film 21 at the location M1 ′ (location of the other leaf spring portion 12c). The shape appears. Therefore, the elastic constants of the two leaf spring portions 12c of one movable plate 12 are the same. As a result, according to the present embodiment, the twist of the movable plate 12 around the X axis can be reduced, and the posture of the movable plate 12 is symmetrical with respect to the symmetry plane P (desired in the present embodiment). Can be maintained with high accuracy. Therefore, according to the present embodiment, when the mirror 31 advances into the optical path and reflects light, the angle of the mirror 31 can be accurately set to a desired angle, and loss of the reflected light amount can be reduced. it can.

  Further, in the present embodiment, the wiring patterns 41b, 42a, and 42b are formed symmetrically with respect to the symmetry plane P also in a region where the movable plate 12 is opposed to the mirror mounting plate 12a. A step shape symmetrical to the plane of symmetry P also appears in 12a and the like. For example, as shown in FIG. 12, the SiN film 21 at locations M2 and M3 (location on one side of the mirror mounting plate 12a) and the SiN film 21 at locations M2 ′ and M3 ′ (location on the other side of the mirror mounting plate 12a). Shows a symmetrical step shape. If the mirror mounting plate 12a or the like of the movable plate 12 is a perfect rigid body, even if an asymmetric stepped shape appears on the mirror mounting plate 12a, the movable plate 12 is not twisted around the X axis. However, although it is reinforced by the convex portion 24, the mirror mounting plate 12a is also formed of a thin film and has a slight spring property. Therefore, when the asymmetric step shape appears on the mirror mounting plate 12a, the mirror mounting plate 12a is slightly movable. The mirror mounting plate 12a of the plate 12 may be twisted around the X axis. According to the present embodiment, such a possibility is eliminated and it is more preferable.

  In contrast, in the comparative example, as described above, by not including the dummy wiring pattern, the wiring patterns 41b, 42a, and 42b are asymmetric with respect to the symmetry plane P in the region facing the movable plate 12. (See FIGS. 16 and 17).

  Therefore, in the comparative example, for example, as shown in FIG. 18, the step shape is not shown at all in the SiN film 21 at the location M1 (location of the one leaf spring portion 12c), whereas the location M1 ′ ( A step shape appears in the SiN film 21 at the other leaf spring portion 12c). Therefore, the elastic constants of the two leaf spring portions 12c of one movable plate 12 are different, the twist of the movable plate 12 around the X axis is increased, and the posture of the movable plate 12 is symmetrical with respect to the symmetry plane P. The posture cannot be accurately maintained. Therefore, according to the comparative example, when the mirror 31 advances into the optical path and reflects light, the angle of the mirror 31 cannot be accurately set to a desired angle, and the loss of reflected light amount increases.

  In the comparative example, for example, as shown in FIG. 18, the step shape is not shown at all in the SiN film 21 at the locations M2 and M3 ′ (location on one side of the mirror mounting plate 12a). A step shape appears in the SiN film 21 at the locations M2 ′ and M3 (location on the other side of the mirror mounting plate 12a). Therefore, even if the mirror mounting plate 12a or the like of the movable plate 12 is not a perfect rigid body, the mirror mounting plate 12a of the movable plate 12 is slightly twisted.

  Incidentally, the resist 100 in FIG. 18 is formed even when the wiring patterns 41b, 42a, and 42b are not formed symmetrically with respect to the symmetry plane P in the region facing the movable plate 12 as in the comparative example. Later, if the resist 100 is flattened by a flattening process such as a CMP process, the twist of the movable plate 12 around the X axis can be reduced. However, even if the resist 100 is flattened by a flattening process such as a CMP process, complete flattening is practically difficult, and thus an asymmetric step shape appears in the region facing the two leaf spring portions 12c. The twist of the movable plate 12 around the X axis cannot be reduced as in this embodiment. In addition, if a planarization process such as a CMP process is performed, the number of processes increases correspondingly and cost increases cannot be avoided.

  [Second Embodiment]

  FIG. 19 shows the arrangement of the Lorentz force wiring pattern 42a, the movable electrode wiring pattern 42b, the fixed electrode 41a, and the fixed electrode wiring pattern 41b on the substrate 11 in the entire optical switch array according to the second embodiment of the present invention. FIG. 10 is a schematic plan view corresponding to FIG.

  The difference between the present embodiment and the first embodiment is only the dummy wiring pattern among the wiring patterns 41b, 42a, and 42b. That is, in the first embodiment, a dummy wiring pattern as shown in FIG. 19 (a wiring pattern shown in FIG. 19 and not shown in FIG. 16 is used instead of the dummy wiring pattern shown by a solid line in FIG. 42a ′, 42b ′) is only employed. The dummy wiring patterns 42a ′ and 42b ′ employed in the present embodiment are symmetrical with respect to the plane of symmetry P in each region of the movable plate 12 facing the two leaf spring portions 12c of the movable plate 12. The wiring patterns 42a and 42b are formed only in the vicinity of the region facing the leaf spring portion 12c so that the wiring patterns 42a and 42b are formed.

  According to the present embodiment, the wiring patterns 41b, 42a, 42b, 42a ′, and 42b ′ are not formed symmetrically with respect to the symmetry plane P in the region of the movable plate 12 facing the mirror mounting plate 12a. Compared with the first embodiment, the effect of reducing the twist about the X axis of the mirror mounting plate 12a is slightly inferior, but in the region facing the two leaf spring portions 12c as in the first embodiment. Since the wiring patterns 42a, 42b, 42a ′, 42b ′ are formed symmetrically with respect to the symmetry plane P, a considerable twist reduction effect can be obtained.

  [Third Embodiment]

  FIG. 20 is a schematic cross-sectional view schematically showing an intermediate state of the manufacturing process of the optical switch array according to the third embodiment of the present invention, and corresponds to FIG.

  FIG. 21 is a schematic plan view schematically showing the electrostatic shield layer 50 used in the optical switch array according to the present embodiment.

  The optical switch array according to the present embodiment differs from the optical switch array according to the first embodiment in that wiring patterns 41b, 42a, 42b and wiring patterns 22a, 22b of the movable plate 12 are as shown in FIG. An electrostatic shield layer 50 is formed on the insulating film 15 so that an electrostatic shield 50 made of an Al film or the like is positioned between them, and an insulating film 51 such as a silicon oxide film is further formed on the electrostatic shield layer 50. It is only a point that has been done.

  In the present embodiment, as shown in FIG. 21, the electrostatic shield layer 50 is formed so as to cover the entire area where the movable plate 12 is disposed, except for the areas of the openings 50a, 50e, and 50f. Yes. The opening 50a is formed in a region facing the fixed electrode 41a, and the openings 50e and 50f are formed in the region of the leg portions 12e and 12f.

  When the electrostatic shield layer 50 is not formed, depending on the arrangement of the wiring pattern on the movable plate 12 and the wiring pattern on the substrate 11 side, an unintended electrostatic force may be generated between the two when different potentials are applied to them. In addition, the electrostatic force acting on one side with respect to the plane of symmetry P and the electrostatic force acting on the other side may become unbalanced. In such a case, the movable plate 12 may be twisted around the X axis due to the unbalanced electrostatic force.

  According to the present embodiment, since the electrostatic shield layer 50 is formed, an unbalanced electrostatic force can be generated even if the current arrangement of the wiring pattern is modified and the electrostatic shield layer 50 is not present. Even if such an arrangement of wiring patterns is adopted, the electrostatic force does not act between the wiring pattern of the movable plate 12 and the wiring pattern on the substrate 11 side, and the X of the movable plate 12 caused by the electrostatic force between the wiring patterns. Twist around the axis can be prevented. Further, according to the present embodiment, as in the first embodiment, twisting around the X axis of the movable plate 12 due to shape transfer by the wiring pattern formed on the substrate can be reduced. .

  The electrostatic shield layer 50 is not formed in a region covering almost the entire region where the movable plate 12 is disposed as in the present embodiment, but only in the region where the unbalanced electrostatic force described above can occur. It may be partially formed.

  [Fourth Embodiment]

  FIG. 22 is a schematic sectional view schematically showing a state in the middle of the manufacturing process of the optical switch array according to the fourth embodiment of the present invention, and corresponds to FIG.

  The optical switch array according to the present embodiment is obtained by adding the electrostatic shield layer 50 and the insulating film 51 to the optical switch array according to the first embodiment to obtain the optical switch array according to the third embodiment. Similarly, an electrostatic shield layer 50 and an insulating film 51 are added to the optical switch array according to the comparative example.

  According to the present embodiment, since the electrostatic shield layer 50 is formed as in the third embodiment, even if the current arrangement of the wiring pattern is modified, the electrostatic shield layer 50 is Even if a wiring pattern arrangement that can cause an unbalanced electrostatic force in the absence of the wiring pattern is adopted, the electrostatic force does not act between the wiring pattern of the movable plate 12 and the wiring pattern on the substrate 11 side, and the wiring pattern It is possible to prevent the movable plate 12 from being twisted around the X axis due to the electrostatic force.

  However, according to the present embodiment, as in the comparative example, the twist about the X axis of the movable plate 12 due to the shape transfer by the wiring pattern formed on the substrate cannot be reduced.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

  For example, the electric circuit mounted on the microactuator array is not limited to the circuit shown in FIG. 8, and both the fixed electrode and the movable electrode of each microactuator and both ends of the current path for Lorentz force are externally connected independently. Various circuit configurations such as a circuit connected to a terminal for use or a circuit equipped with an address circuit may be employed.

  In each of the above-described embodiments, the present invention is applied to a microactuator array or an optical switch array. However, the present invention is not limited to an array, and a single microactuator or It can also be applied to a single optical switch.

  Further, each of the above-described embodiments is an example in which the present invention is applied to a microactuator of a type in which the movable portion has a cantilever structure, but the present invention is not limited to this, for example, The present invention can also be applied to a microactuator of a type in which the movable part as disclosed in Patent Document 2 has a double-sided structure.

  In addition, each of the above-described embodiments is an example in which the microactuator according to the present invention is applied to an optical switch. However, the present invention replaces the mirror 31 with a light-shielding film having a low light reflectance and a polarization characteristic. By mounting the polarizing film, the optical thin film having the optical wavelength filter characteristic, etc., it can be applied to various optical devices such as an optical attenuator, a polarizer, and a wavelength selector. For example, since the mirror 31 can be used as it is as a shutter, the optical switch employed in the optical switch array according to the first embodiment can be used as it is as a variable optical attenuator. In this case, by controlling the magnitude of the electrostatic force voltage or the Lorentz force current, the mirror 31 is stopped at a desired position in the middle of the optical path, and the light passing through the optical path is attenuated by a desired amount. Can do. In this case, only one of electrostatic force and Lorentz force may be used. In the case of a variable optical attenuator, a shutter with low light reflectance may be used instead of the mirror 31.

It is a schematic block diagram which shows typically an example of the optical system using the optical switch array by the 1st Embodiment of this invention. FIG. 2 is a schematic plan view schematically showing the optical switch array in FIG. 1. FIG. 2 is a schematic plan view schematically showing one optical switch as a unit element of the optical switch array in FIG. 1. FIG. 4 is a schematic cross-sectional view along the line A-A ′ in FIG. 3. It is a figure which shows the pattern shape of Al film when the movable plate 12 in FIG. 3 is seen from the top. FIG. 6 is a schematic cross-sectional view taken along the line B-B ′ in FIGS. 3 and 5 as viewed from the + Y side in the −Y-axis direction, showing a state in which the mirror is held on the upper side. FIG. 6 is a schematic cross-sectional view taken along the line B-B ′ in FIGS. 3 and 5 as viewed from the + Y side in the −Y-axis direction, showing a state where the mirror is held on the side. FIG. 2 is an electric circuit diagram showing the optical switch array in FIG. 1. FIG. 2 is a schematic plan view showing the arrangement of wiring patterns and movable electrodes on a movable plate in the entire optical switch array in FIG. 1. FIG. 2 is a schematic plan view showing an arrangement of wiring patterns and fixed electrodes on a substrate in the entire optical switch array in FIG. 1. It is the general | schematic enlarged plan view which expanded a part in FIG. It is a schematic sectional drawing which shows typically the state in the middle of the manufacturing process of the optical switch array 1 in FIG. It is a timing chart of the electric potential and electric current which an external control circuit gives to each terminal. 10 is another timing chart of potentials and currents applied to each terminal by the external control circuit. It is a schematic plan view which shows the dummy wiring pattern in FIG. It is a schematic plan view which shows arrangement | positioning of the wiring pattern on a board | substrate in the whole optical switch array by a comparative example, and a fixed electrode. FIG. 17 is a schematic enlarged plan view in which a part of FIG. 16 is enlarged. It is a schematic sectional drawing which shows typically the state in the middle of the manufacturing process of the optical switch array by a comparative example. It is a schematic plan view which shows the arrangement | positioning of the wiring pattern on a board | substrate in the whole optical switch array by the 2nd Embodiment of this invention, and a fixed electrode. It is a schematic sectional drawing which shows typically the state in the middle of the manufacturing process of the optical switch array by the 3rd Embodiment of this invention. It is a schematic plan view which shows typically the electrostatic shielding layer used with the optical switch array by the 3rd Embodiment of this invention. It is a schematic sectional drawing which shows typically the state in the middle of the manufacturing process of the optical switch array by the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical switch array 11 Board | substrate 12 Movable plate 12a Mirror mounting plate 12b Support plate (beam part)
12c Leaf spring part (elastic part)
12d Connecting portion 12e, 12f Leg 22a Lorentz force wiring pattern 22b Movable electrode wiring pattern 22d Movable electrode 41a Fixed electrode 41b Fixed electrode wiring pattern 42a Lorentz force wiring pattern 42b Movable electrode wiring pattern 31 Mirror (driven body)
50 Electrostatic shield layer

Claims (9)

A substrate and a movable part supported by the substrate and movable relative to the substrate;
The movable part is composed of a thin film,
The movable part includes one or more elastic parts provided substantially symmetrically with respect to a predetermined plane perpendicular to the surface of the substrate,
A microactuator, wherein a film pattern is formed on the substrate substantially symmetrically with respect to the predetermined surface in a region facing the one or more elastic portions.   The microactuator according to claim 1, wherein the movable portion has a cantilever structure in which a fixed end is fixed to the substrate. The movable portion includes first and second beam portions mechanically connected in parallel to each other and symmetrically arranged with respect to the predetermined plane between the fixed end and the free end of the movable portion. ,
The first beam portion includes one of the one or more elastic portions,
3. The microactuator according to claim 1, wherein the second beam portion includes another one of the one or more elastic portions.   The microactuator according to claim 1, wherein at least a part of the film pattern is at least a part of a wiring pattern. The movable part has a wiring pattern;
A wiring pattern is formed on the substrate,
5. An electrostatic shield layer is formed between at least a part of the wiring pattern of the movable part and at least a part of the wiring pattern on the substrate opposite to the wiring pattern. The microactuator according to any one of the above. A substrate and a movable part supported by the substrate and movable relative to the substrate;
The movable part has a wiring pattern;
The movable part includes one or more elastic parts provided substantially symmetrically with respect to a predetermined plane perpendicular to the surface of the substrate,
A wiring pattern is formed on the substrate,
An electrostatic shield layer is formed between at least a part of the wiring pattern of the movable part and at least a part of the wiring pattern on the substrate opposite to the wiring pattern ,
The electrostatic shield layer is formed on the predetermined surface between the at least part of the wiring pattern of the movable part and the at least part of the wiring pattern on the substrate when the electrostatic shield layer is not provided. A microactuator formed in a region where an unbalanced electrostatic force can be generated .   An optical apparatus comprising: the microactuator according to claim 1; and an optical element provided in the movable portion.   A microactuator array comprising a plurality of the microactuators according to claim 1, wherein the movable parts of the plurality of microactuators are two-dimensionally arranged on the same substrate.   9. An optical device comprising: the microactuator array according to claim 8; and an optical element provided on each of the movable parts of the plurality of microactuators.

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